1 00:00:12,370 --> 00:00:09,820 I had the pleasure of talking about 2 00:00:15,249 --> 00:00:12,380 Hayes's at the last exit climbs and for 3 00:00:16,960 --> 00:00:15,259 those of you who were there I said most 4 00:00:19,420 --> 00:00:16,970 of the time just talking about kind of 5 00:00:21,130 --> 00:00:19,430 general information about how Hayes 6 00:00:22,380 --> 00:00:21,140 pricks in about how we think about Hayes 7 00:00:25,479 --> 00:00:22,390 and some of the lessons we've learned 8 00:00:27,190 --> 00:00:25,489 from the earth community in part that's 9 00:00:30,130 --> 00:00:27,200 because at the time there hadn't really 10 00:00:32,139 --> 00:00:30,140 been a lot of work done on trying to 11 00:00:34,000 --> 00:00:32,149 understand Hayes and exoplanet 12 00:00:35,260 --> 00:00:34,010 atmospheres and I think I ended that 13 00:00:37,870 --> 00:00:35,270 talk when I went back and looked at my 14 00:00:39,460 --> 00:00:37,880 slides with um this is very like 15 00:00:40,960 --> 00:00:39,470 optimistic if we get these proposals 16 00:00:41,800 --> 00:00:40,970 funded we're actually going to do some 17 00:00:43,870 --> 00:00:41,810 work 18 00:00:45,850 --> 00:00:43,880 we got the proposals funded we did the 19 00:00:47,440 --> 00:00:45,860 work and now I found myself suddenly 20 00:00:50,560 --> 00:00:47,450 trying to figure out how to talk about 21 00:00:52,330 --> 00:00:50,570 all of that in the time allotted so 22 00:00:54,340 --> 00:00:52,340 things have changed quite a bit since 23 00:00:56,200 --> 00:00:54,350 the last Expo climbs I know you all are 24 00:00:58,750 --> 00:00:56,210 familiar with how fast-paced this field 25 00:01:01,330 --> 00:00:58,760 is but I have a lot to tell you about 26 00:01:04,479 --> 00:01:01,340 today first I just want to start off 27 00:01:06,010 --> 00:01:04,489 quickly reminding maybe everybody why we 28 00:01:08,260 --> 00:01:06,020 care about Hayes we've heard it come up 29 00:01:09,880 --> 00:01:08,270 a little bit already today and I'm gonna 30 00:01:11,410 --> 00:01:09,890 use the same definition that everyone 31 00:01:12,820 --> 00:01:11,420 has been using today which is when I'm 32 00:01:14,920 --> 00:01:12,830 talking about Hayes I'm talking about 33 00:01:18,399 --> 00:01:14,930 particles produced by photochemistry 34 00:01:19,719 --> 00:01:18,409 I'm not talking about cloud so we care 35 00:01:21,370 --> 00:01:19,729 about Hayes for lots of reasons in 36 00:01:23,469 --> 00:01:21,380 planetary atmospheres I think the one 37 00:01:25,210 --> 00:01:23,479 that often comes up in this crowd is 38 00:01:26,649 --> 00:01:25,220 that it's signal is present and remote 39 00:01:27,580 --> 00:01:26,659 sensing observations sometimes 40 00:01:29,500 --> 00:01:27,590 frustratingly 41 00:01:31,390 --> 00:01:29,510 but I'm hopeful as Caroline mentioned 42 00:01:33,640 --> 00:01:31,400 this morning that we can start thinking 43 00:01:35,230 --> 00:01:33,650 about these particles as information 44 00:01:36,280 --> 00:01:35,240 rather than frustration that are going 45 00:01:39,310 --> 00:01:36,290 to help us figure out how these 46 00:01:40,810 --> 00:01:39,320 atmospheres work we know that they 47 00:01:42,460 --> 00:01:40,820 affect the radiation budget of the 48 00:01:44,109 --> 00:01:42,470 atmosphere and also the surface if the 49 00:01:45,730 --> 00:01:44,119 planet has a surface because particles 50 00:01:49,929 --> 00:01:45,740 interact with light differently than 51 00:01:51,700 --> 00:01:49,939 gases do if we have a surface it's also 52 00:01:53,560 --> 00:01:51,710 possible that these particles could be 53 00:01:55,000 --> 00:01:53,570 providing a source of organic material 54 00:01:57,429 --> 00:01:55,010 to the surface and that might be an 55 00:01:59,310 --> 00:01:57,439 important part of the organic inventory 56 00:02:01,420 --> 00:01:59,320 for that world and so that might have 57 00:02:03,340 --> 00:02:01,430 important consequences for things like 58 00:02:04,300 --> 00:02:03,350 the origin or evolution of life if we're 59 00:02:07,300 --> 00:02:04,310 thinking about how the bit of 60 00:02:09,490 --> 00:02:07,310 habitability and one of the things that 61 00:02:11,589 --> 00:02:09,500 I also think is really important not to 62 00:02:13,269 --> 00:02:11,599 forget is that these particles are a 63 00:02:14,199 --> 00:02:13,279 record of the atmosphere and atmospheric 64 00:02:16,089 --> 00:02:14,209 processes 65 00:02:17,410 --> 00:02:16,099 by the time a particle ends up on the 66 00:02:19,240 --> 00:02:17,420 surface of a planet or in the deep 67 00:02:20,800 --> 00:02:19,250 atmosphere of the planet that particle 68 00:02:24,429 --> 00:02:20,810 has experienced every temperature 69 00:02:25,720 --> 00:02:24,439 pressure background gas mixture exposure 70 00:02:27,910 --> 00:02:25,730 to different wavelengths of photons 71 00:02:29,709 --> 00:02:27,920 energetic particles condensation 72 00:02:31,539 --> 00:02:29,719 transport all of these particle all of 73 00:02:33,399 --> 00:02:31,549 these processes have affected the 74 00:02:34,839 --> 00:02:33,409 particles and we think that most of 75 00:02:36,819 --> 00:02:34,849 those processes should leave their 76 00:02:38,319 --> 00:02:36,829 fingerprint on the particles and so if 77 00:02:40,390 --> 00:02:38,329 we can start to really understand how 78 00:02:42,220 --> 00:02:40,400 those processes work we really will have 79 00:02:43,990 --> 00:02:42,230 a good record of the atmosphere and 80 00:02:49,179 --> 00:02:44,000 atmospheric processes encoded in these 81 00:02:51,159 --> 00:02:49,189 particles okay so if you're gonna try to 82 00:02:52,750 --> 00:02:51,169 understand haze and I think a lot of you 83 00:02:53,920 --> 00:02:52,760 know that I mostly study Titan or at 84 00:02:56,050 --> 00:02:53,930 least I did at some point in my career 85 00:02:58,059 --> 00:02:56,060 if you're gonna study haze in the solar 86 00:03:00,069 --> 00:02:58,069 system the best place to do it is Titan 87 00:03:01,449 --> 00:03:00,079 but I think that all of the studying of 88 00:03:03,459 --> 00:03:01,459 Titan has done us a little bit of 89 00:03:04,869 --> 00:03:03,469 disservice and so I'm going to spend a 90 00:03:07,089 --> 00:03:04,879 good chunk of today trying to dissuade 91 00:03:08,649 --> 00:03:07,099 you of some of the lessons that we may 92 00:03:10,720 --> 00:03:08,659 have learned from Titan because we 93 00:03:12,399 --> 00:03:10,730 learned them incorrectly so this is an 94 00:03:14,379 --> 00:03:12,409 image from Voyager as Voyager flew 95 00:03:16,360 --> 00:03:14,389 through the Saturn system and beamed 96 00:03:17,679 --> 00:03:16,370 back this really frustrating image we 97 00:03:20,949 --> 00:03:17,689 were unable to see the surface 98 00:03:22,689 --> 00:03:20,959 everything okay it's free okay 99 00:03:24,610 --> 00:03:22,699 well it's just an orange ball you're not 100 00:03:26,680 --> 00:03:24,620 actually missing anything you're 101 00:03:28,300 --> 00:03:26,690 literally missing nothing uh-huh a 102 00:03:29,439 --> 00:03:28,310 little bit later you might want to see 103 00:03:32,710 --> 00:03:29,449 what's on the slides but at this moment 104 00:03:35,009 --> 00:03:32,720 see I told you it's just nothing to see 105 00:03:39,129 --> 00:03:37,270 you know we knew that it was this easy 106 00:03:40,780 --> 00:03:39,139 world and Voyager was carrying an 107 00:03:42,969 --> 00:03:40,790 infrared spectrometer and so we were 108 00:03:44,259 --> 00:03:42,979 able to get some composition information 109 00:03:45,969 --> 00:03:44,269 and some of these molecules may look 110 00:03:48,069 --> 00:03:45,979 familiar to some of you there's hydrogen 111 00:03:51,460 --> 00:03:48,079 cyanide there's si and there's propane 112 00:03:54,280 --> 00:03:51,470 there's acetylene all kinds of carbon 113 00:03:56,050 --> 00:03:54,290 containing molecules there was only one 114 00:03:58,179 --> 00:03:56,060 nitrogen kentuc containing molecule 115 00:04:00,099 --> 00:03:58,189 detected by Voyager that was hydrogen 116 00:04:03,969 --> 00:04:00,109 cyanide all of the other molecules that 117 00:04:06,909 --> 00:04:03,979 Voyager found were hydrocarbon and so we 118 00:04:08,679 --> 00:04:06,919 kind of left the Voyager era studying 119 00:04:10,569 --> 00:04:08,689 Titan with this idea in our head that 120 00:04:11,800 --> 00:04:10,579 turned out to not be correct and we've 121 00:04:13,449 --> 00:04:11,810 learned a lot from Cassini but 122 00:04:16,509 --> 00:04:13,459 unfortunately some of these these 123 00:04:18,370 --> 00:04:16,519 messages kind of stuck and so we left 124 00:04:20,199 --> 00:04:18,380 the Voyager air kind of with this idea 125 00:04:22,060 --> 00:04:20,209 that organic haze is produced from 126 00:04:23,379 --> 00:04:22,070 methane photochemistry in mildly 127 00:04:26,890 --> 00:04:23,389 reducing atmospheres tightened 128 00:04:27,790 --> 00:04:26,900 atmospheres a mildly reduced officer and 129 00:04:29,020 --> 00:04:27,800 so 130 00:04:30,580 --> 00:04:29,030 you will often hear and I've already 131 00:04:33,879 --> 00:04:30,590 heard it said multiple times today 132 00:04:35,920 --> 00:04:33,889 tightens hydrocarbon haze sorry Caroline 133 00:04:38,159 --> 00:04:35,930 she's looking at me like was it mean yes 134 00:04:40,809 --> 00:04:38,169 I'm sorry it wasn't just you though 135 00:04:42,610 --> 00:04:40,819 so you know we came out of the voyager 136 00:04:44,379 --> 00:04:42,620 area with this idea right it's hazy we 137 00:04:47,350 --> 00:04:44,389 see hydrocarbons in the gas phase that 138 00:04:48,820 --> 00:04:47,360 the pain must be hydrocarbon and in the 139 00:04:50,830 --> 00:04:48,830 interim we didn't have the opportunity 140 00:04:53,200 --> 00:04:50,840 to get a lot more information about the 141 00:04:55,210 --> 00:04:53,210 haze and so instead we turned to 142 00:04:57,040 --> 00:04:55,220 laboratory experiments tried to try to 143 00:04:59,230 --> 00:04:57,050 study the processes that were resulting 144 00:05:00,760 --> 00:04:59,240 in haze formation while we were waiting 145 00:05:03,249 --> 00:05:00,770 for another mission and we had to wait 146 00:05:05,469 --> 00:05:03,259 quite a number of years and so there 147 00:05:07,659 --> 00:05:05,479 were a number of nitrogen and methane 148 00:05:09,070 --> 00:05:07,669 photo chemistry experiments of the type 149 00:05:10,540 --> 00:05:09,080 that I'm going to describe in 150 00:05:12,520 --> 00:05:10,550 excruciating detail here in a few 151 00:05:14,320 --> 00:05:12,530 minutes that were designed to try to 152 00:05:16,450 --> 00:05:14,330 understand haze formation and type of 153 00:05:18,219 --> 00:05:16,460 atmosphere and I want to tell you two 154 00:05:20,260 --> 00:05:18,229 important takeaway lessons that we learn 155 00:05:21,969 --> 00:05:20,270 from those experiments that turned out 156 00:05:25,119 --> 00:05:21,979 to be really important when we started 157 00:05:27,100 --> 00:05:25,129 getting Cassini data back so one thing 158 00:05:30,010 --> 00:05:27,110 that we learned from experiments done by 159 00:05:32,649 --> 00:05:30,020 multiple groups different different labs 160 00:05:35,260 --> 00:05:32,659 across quite a bit of time is that 161 00:05:38,709 --> 00:05:35,270 nitrogen preferentially partitions into 162 00:05:39,999 --> 00:05:38,719 the solid phase and so the vision we got 163 00:05:42,159 --> 00:05:40,009 from looking at the gas phase was that 164 00:05:44,620 --> 00:05:42,169 the nitrogen wasn't participating in the 165 00:05:46,330 --> 00:05:44,630 chemistry but that was not correct at 166 00:05:48,249 --> 00:05:46,340 all in fact the nitrogen is very 167 00:05:49,570 --> 00:05:48,259 actively participating in the chemistry 168 00:05:51,580 --> 00:05:49,580 and that's something that we've seen 169 00:05:54,760 --> 00:05:51,590 from a lot of data that were taken from 170 00:05:56,080 --> 00:05:54,770 the Cassini mass spectrometer and so one 171 00:05:57,820 --> 00:05:56,090 of the reasons we don't see as much of 172 00:05:59,589 --> 00:05:57,830 it in the gas phase is because when it 173 00:06:01,089 --> 00:05:59,599 participates in the chemistry it wants 174 00:06:02,320 --> 00:06:01,099 to go into the solid and that's 175 00:06:05,050 --> 00:06:02,330 something that we learn from these lab 176 00:06:06,640 --> 00:06:05,060 experiments one of the other things that 177 00:06:08,640 --> 00:06:06,650 we learned from these lab experiments is 178 00:06:10,779 --> 00:06:08,650 that the presence of molecular nitrogen 179 00:06:12,459 --> 00:06:10,789 dramatically increases the production 180 00:06:14,890 --> 00:06:12,469 rate of particles in these experiments 181 00:06:17,050 --> 00:06:14,900 if you switch out molecular nitrogen for 182 00:06:18,820 --> 00:06:17,060 argon in most of these experiments you 183 00:06:21,240 --> 00:06:18,830 decrease your production rate by orders 184 00:06:24,730 --> 00:06:21,250 of magnitude so the nitrogen is very 185 00:06:27,070 --> 00:06:24,740 important it has a role that it plays in 186 00:06:28,869 --> 00:06:27,080 how the energy moves that drives the 187 00:06:30,430 --> 00:06:28,879 chemistry it's also actively 188 00:06:32,050 --> 00:06:30,440 participating in the chemistry itself 189 00:06:34,029 --> 00:06:32,060 partitioning into the salt so the 190 00:06:35,740 --> 00:06:34,039 nitrogen is really important and we tend 191 00:06:37,990 --> 00:06:35,750 to forget about it when we talk about 192 00:06:40,089 --> 00:06:38,000 nitrogen when we talk about Titans 193 00:06:40,380 --> 00:06:40,099 hydrocarbon haze so I prefer Titans or 194 00:06:43,380 --> 00:06:40,390 again 195 00:06:45,690 --> 00:06:43,390 case the decent description Titans very 196 00:06:48,120 --> 00:06:45,700 messy haze Titans whatever is going on 197 00:06:49,350 --> 00:06:48,130 in their haze I don't know it's but the 198 00:06:51,150 --> 00:06:49,360 reason that I want to dissuade you of 199 00:06:53,580 --> 00:06:51,160 this is because carbon because methane 200 00:06:55,260 --> 00:06:53,590 isn't the only important molecule for 201 00:06:56,700 --> 00:06:55,270 haze formation and hydrocarbons are not 202 00:06:58,230 --> 00:06:56,710 the only important molecules for haze 203 00:07:00,480 --> 00:06:58,240 formation and I'm gonna step you through 204 00:07:02,100 --> 00:07:00,490 a bunch of experiments that have shown 205 00:07:05,280 --> 00:07:02,110 this including the work that we've been 206 00:07:06,930 --> 00:07:05,290 doing specifically for exoplanets so I 207 00:07:09,000 --> 00:07:06,940 want to show you one more thing that we 208 00:07:12,090 --> 00:07:09,010 learned from Titan because I think it's 209 00:07:13,650 --> 00:07:12,100 really important Cassini was carrying a 210 00:07:16,290 --> 00:07:13,660 mass spectrometer that was designed to 211 00:07:18,750 --> 00:07:16,300 study the gas phase composition of 212 00:07:21,570 --> 00:07:18,760 Titan's atmosphere in sidhu it had a 213 00:07:24,530 --> 00:07:21,580 mass range that went up to 99 amu so 214 00:07:27,030 --> 00:07:24,540 that's five or six heavy carbon atoms if 215 00:07:28,710 --> 00:07:27,040 this you know so what we basically 216 00:07:30,210 --> 00:07:28,720 thought was that this was what it was 217 00:07:31,530 --> 00:07:30,220 gonna look like if we looked at a mass 218 00:07:33,210 --> 00:07:31,540 spectrum so this is let's see if I can 219 00:07:35,490 --> 00:07:33,220 work this without poking an eye out um 220 00:07:37,860 --> 00:07:35,500 this is not to charge on the x-axis this 221 00:07:39,450 --> 00:07:37,870 is number on the y-axis and so we would 222 00:07:40,860 --> 00:07:39,460 assume that this is what a mass spectrum 223 00:07:43,590 --> 00:07:40,870 of Titans upper atmosphere might look 224 00:07:45,900 --> 00:07:43,600 like six or seven heavy carbon atoms 225 00:07:47,280 --> 00:07:45,910 going up to a mass of a hundred in fact 226 00:07:49,320 --> 00:07:47,290 the heaviest molecule that had ever been 227 00:07:52,050 --> 00:07:49,330 detected prior to the arrival of Cassini 228 00:07:55,800 --> 00:07:52,060 was benzene just c6h6 that has a mass of 229 00:07:57,450 --> 00:07:55,810 78 so it turns out that we were really 230 00:07:59,430 --> 00:07:57,460 lucky because in addition to the mass 231 00:08:01,050 --> 00:07:59,440 spectrometer that was very carefully 232 00:08:03,360 --> 00:08:01,060 designed to study Titan's atmosphere in 233 00:08:04,950 --> 00:08:03,370 great detail Cassini was also carrying a 234 00:08:06,750 --> 00:08:04,960 plasma spectrometer that wasn't meant to 235 00:08:09,090 --> 00:08:06,760 study Titan at all it was meant to 236 00:08:10,770 --> 00:08:09,100 characterize the small energetic ions in 237 00:08:13,620 --> 00:08:10,780 the Saturnia mini magnetosphere things 238 00:08:14,940 --> 00:08:13,630 like okhla but they didn't turn it off 239 00:08:17,250 --> 00:08:14,950 when it flew through Titan's atmosphere 240 00:08:21,990 --> 00:08:17,260 and then we saw data those like this 241 00:08:24,900 --> 00:08:22,000 instead so that's a log axis so Cassini 242 00:08:27,840 --> 00:08:24,910 detected ions in this case negative ions 243 00:08:30,090 --> 00:08:27,850 with a master charge up to 10,000 amu in 244 00:08:33,300 --> 00:08:30,100 Titan's atmosphere that's more like six 245 00:08:36,690 --> 00:08:33,310 or seven or eight hundred heavy atom not 246 00:08:38,490 --> 00:08:36,700 six or seven six or 700 so we were wrong 247 00:08:40,320 --> 00:08:38,500 by a couple orders of magnitude and our 248 00:08:42,000 --> 00:08:40,330 understanding of how complicated the 249 00:08:44,430 --> 00:08:42,010 chemistry is in Titan's atmosphere and 250 00:08:47,730 --> 00:08:44,440 this is at an altitude of 950 kilometers 251 00:08:49,020 --> 00:08:47,740 above the surface the mean free path in 252 00:08:51,540 --> 00:08:49,030 this region of the atmosphere is about a 253 00:08:53,490 --> 00:08:51,550 kilometer so we're still trying to sort 254 00:08:54,240 --> 00:08:53,500 out exactly how one goes about building 255 00:08:56,040 --> 00:08:54,250 something that has 256 00:08:58,550 --> 00:08:56,050 six or seven hundred carbon atoms when 257 00:09:00,690 --> 00:08:58,560 you barely ever interact with anything 258 00:09:01,680 --> 00:09:00,700 just to give you a sense of scale for 259 00:09:03,300 --> 00:09:01,690 those of you who don't think about 260 00:09:06,150 --> 00:09:03,310 chemistry very often there's our friend 261 00:09:07,650 --> 00:09:06,160 benzene massive 78 i sat in chem draw 262 00:09:09,540 --> 00:09:07,660 one day and it took me a full day 263 00:09:11,520 --> 00:09:09,550 because programs don't like drawing 264 00:09:14,130 --> 00:09:11,530 molecules this big to draw something 265 00:09:15,480 --> 00:09:14,140 that is not a real chemistry thing but 266 00:09:17,400 --> 00:09:15,490 that's just to give you a sense of scale 267 00:09:20,730 --> 00:09:17,410 of how wrong we were about the 268 00:09:22,650 --> 00:09:20,740 complexity and so we had this idea 269 00:09:24,960 --> 00:09:22,660 before Cassini that the haze particles 270 00:09:27,810 --> 00:09:24,970 formed where we see them because that's 271 00:09:29,220 --> 00:09:27,820 how it works on earth and in Titan's 272 00:09:31,190 --> 00:09:29,230 atmosphere where we really see the 273 00:09:33,780 --> 00:09:31,200 particles as deep in the stratosphere 274 00:09:35,400 --> 00:09:33,790 but this is in the ionosphere and this 275 00:09:38,400 --> 00:09:35,410 is where the processes that leads to 276 00:09:40,050 --> 00:09:38,410 haze formation on Titan start and if you 277 00:09:41,700 --> 00:09:40,060 look in the ultraviolet in this region 278 00:09:43,710 --> 00:09:41,710 of the atmosphere you can already see 279 00:09:45,030 --> 00:09:43,720 that there are particles in the 280 00:09:46,380 --> 00:09:45,040 atmosphere that are interacting with 281 00:09:49,020 --> 00:09:46,390 light of the third particle and not a 282 00:09:52,770 --> 00:09:49,030 gas so this has really changed our 283 00:09:54,510 --> 00:09:52,780 understanding of aerosol formation we 284 00:09:56,280 --> 00:09:54,520 thought then ok Titan must be this 285 00:09:58,500 --> 00:09:56,290 unique unicorn and it has this really 286 00:10:00,560 --> 00:09:58,510 weird chemistry but it turned out that 287 00:10:03,660 --> 00:10:00,570 Cassini had a few more surprises for us 288 00:10:05,190 --> 00:10:03,670 so we think that maybe Titan is not the 289 00:10:06,900 --> 00:10:05,200 exception and it's possible that it may 290 00:10:08,790 --> 00:10:06,910 be the rule for a lot of these types of 291 00:10:10,800 --> 00:10:08,800 atmospheres so this is Saturn now 292 00:10:12,480 --> 00:10:10,810 similar to the spectrum that I showed 293 00:10:14,280 --> 00:10:12,490 you a few minutes ago of Titan you'll 294 00:10:15,960 --> 00:10:14,290 see similar molecules so just to give 295 00:10:17,400 --> 00:10:15,970 you a sense of scale of the types of 296 00:10:20,010 --> 00:10:17,410 things we're seeing in the gas phase we 297 00:10:21,360 --> 00:10:20,020 see methane we see a tiny sea acetylene 298 00:10:24,570 --> 00:10:21,370 again these hydrocarbons 299 00:10:26,730 --> 00:10:24,580 so Cassini's last act was to be 300 00:10:28,920 --> 00:10:26,740 intentionally crashed into saturn and 301 00:10:31,520 --> 00:10:28,930 one of the main goals of the end of 302 00:10:34,950 --> 00:10:31,530 mission was send back mass spectral data 303 00:10:38,700 --> 00:10:34,960 of Saturn's upper atmosphere and this is 304 00:10:40,380 --> 00:10:38,710 what they look like so we thought with 305 00:10:42,329 --> 00:10:40,390 our understanding of how Saturn worked 306 00:10:44,310 --> 00:10:42,339 that the only thing we were going to see 307 00:10:46,710 --> 00:10:44,320 we're right here are hydrogen and helium 308 00:10:48,090 --> 00:10:46,720 that's it the only thing that we should 309 00:10:50,190 --> 00:10:48,100 see in that region the atmosphere based 310 00:10:51,720 --> 00:10:50,200 on our understanding of Saturn but 311 00:10:54,410 --> 00:10:51,730 instead we see all of these so that's 312 00:10:57,390 --> 00:10:54,420 methane there's ammonia there's water 313 00:11:01,020 --> 00:10:57,400 this is what's the molecular nitrogen 314 00:11:03,540 --> 00:11:01,030 and carbon monoxide there's co2 this one 315 00:11:05,710 --> 00:11:03,550 over here is benzene there's potentially 316 00:11:07,840 --> 00:11:05,720 some toluene hiding over here 317 00:11:09,460 --> 00:11:07,850 so the chemistry occurring in Saturn's 318 00:11:10,750 --> 00:11:09,470 atmosphere is also very complicated 319 00:11:12,970 --> 00:11:10,760 again this is at the top of the 320 00:11:14,650 --> 00:11:12,980 atmosphere and so we really had to 321 00:11:17,080 --> 00:11:14,660 rethink a lot of our ideas about how 322 00:11:18,670 --> 00:11:17,090 these processes work and so of course 323 00:11:21,430 --> 00:11:18,680 when these data came back from from 324 00:11:23,860 --> 00:11:21,440 Cassini especially from Titan we were 325 00:11:26,800 --> 00:11:23,870 kind of flummoxed at the time I was a 326 00:11:29,170 --> 00:11:26,810 photochemical modeler with my primary 327 00:11:31,420 --> 00:11:29,180 expertise being Titan and we looked at 328 00:11:33,130 --> 00:11:31,430 those data and thought there's no way we 329 00:11:35,260 --> 00:11:33,140 can use a photochemical model to figure 330 00:11:36,730 --> 00:11:35,270 out what these molecules are and we 331 00:11:38,680 --> 00:11:36,740 wanted to know because we're interested 332 00:11:40,450 --> 00:11:38,690 in prebiotic chemistry for Titan and so 333 00:11:42,130 --> 00:11:40,460 we couldn't figure it out from the data 334 00:11:44,020 --> 00:11:42,140 the instrument wasn't designed to do it 335 00:11:46,030 --> 00:11:44,030 we couldn't figure it out for models 336 00:11:48,460 --> 00:11:46,040 because models just aren't that good for 337 00:11:49,960 --> 00:11:48,470 lots of reason and so we started working 338 00:11:52,150 --> 00:11:49,970 on some of these questions in the lab 339 00:11:54,160 --> 00:11:52,160 and so all the experiments that I'm 340 00:11:55,540 --> 00:11:54,170 going to talk to you about and the 341 00:11:57,520 --> 00:11:55,550 experiments that I mentioned a few 342 00:12:00,670 --> 00:11:57,530 minutes ago I'll operate on the same 343 00:12:02,410 --> 00:12:00,680 principle we take simple abundant 344 00:12:04,450 --> 00:12:02,420 atmospheric gases for the main 345 00:12:06,010 --> 00:12:04,460 constituents of an atmosphere for Titan 346 00:12:07,810 --> 00:12:06,020 the experiments are usually molecular 347 00:12:10,150 --> 00:12:07,820 nitrogen and methane maybe some carbon 348 00:12:12,390 --> 00:12:10,160 monoxide if you were doing Venus you 349 00:12:15,190 --> 00:12:12,400 would have co2 and so2 the main 350 00:12:17,860 --> 00:12:15,200 constituents of the atmosphere we expose 351 00:12:20,200 --> 00:12:17,870 them to an energy source we can use 352 00:12:21,880 --> 00:12:20,210 plasma you can use UV photons people 353 00:12:23,410 --> 00:12:21,890 have used if it's an energy source that 354 00:12:24,910 --> 00:12:23,420 exists in a lab people have used it to 355 00:12:27,820 --> 00:12:24,920 do these experiments these are the two 356 00:12:29,770 --> 00:12:27,830 most common at the point the energy 357 00:12:32,260 --> 00:12:29,780 source and source initiates chemistry 358 00:12:35,200 --> 00:12:32,270 that often results in the formation of a 359 00:12:36,550 --> 00:12:35,210 complex organic solid and these are the 360 00:12:38,170 --> 00:12:36,560 particles that were interested in trying 361 00:12:40,030 --> 00:12:38,180 to study so we want to understand this 362 00:12:42,820 --> 00:12:40,040 process of how we're converting the 363 00:12:45,520 --> 00:12:42,830 gases to particles and then everything 364 00:12:46,930 --> 00:12:45,530 that happens after that people often and 365 00:12:48,610 --> 00:12:46,940 I've heard that this word a number of 366 00:12:50,950 --> 00:12:48,620 times especially yesterday people often 367 00:12:52,540 --> 00:12:50,960 refer to this material as Poland which 368 00:12:54,790 --> 00:12:52,550 was a term that was coined by Carl Sagan 369 00:12:56,800 --> 00:12:54,800 in part because they couldn't come up 370 00:13:00,880 --> 00:12:56,810 with an actual word for what they had 371 00:13:02,710 --> 00:13:00,890 made when people say so in almost all of 372 00:13:05,110 --> 00:13:02,720 the time and I think every time it came 373 00:13:07,240 --> 00:13:05,120 up yesterday you actually mean one 374 00:13:11,320 --> 00:13:07,250 specific paper that was published in 375 00:13:13,660 --> 00:13:11,330 1984 his car a 1984 those experiments 376 00:13:15,520 --> 00:13:13,670 were erected specifically for Titan but 377 00:13:16,990 --> 00:13:15,530 they were run at room temperature but 378 00:13:18,069 --> 00:13:17,000 the 90% nitrogen 379 00:13:20,769 --> 00:13:18,079 10% methane 380 00:13:22,479 --> 00:13:20,779 mixture the energy source matters less 381 00:13:24,850 --> 00:13:22,489 to this audience but that's actually a 382 00:13:26,530 --> 00:13:24,860 decent energy source and on top of that 383 00:13:27,939 --> 00:13:26,540 it was a closed experiment which is not 384 00:13:31,600 --> 00:13:27,949 a way that we run experiments anymore 385 00:13:33,999 --> 00:13:31,610 the energy is too high the only reason 386 00:13:35,679 --> 00:13:34,009 that everybody uses this one is because 387 00:13:37,449 --> 00:13:35,689 this is the only one that has optical 388 00:13:40,840 --> 00:13:37,459 constants over the entire wavelength 389 00:13:43,389 --> 00:13:40,850 range that you all want and so I say 390 00:13:45,669 --> 00:13:43,399 this only as a reminder to just not 391 00:13:48,639 --> 00:13:45,679 forget what these particles were made 392 00:13:51,400 --> 00:13:48,649 for they weren't made to be used for 393 00:13:53,049 --> 00:13:51,410 every atmosphere ever in the universe in 394 00:13:58,720 --> 00:13:53,059 part because we didn't know how many 395 00:14:00,519 --> 00:13:58,730 atmospheres there were in 1984 and but 396 00:14:02,439 --> 00:14:00,529 also to say that I understand why people 397 00:14:03,939 --> 00:14:02,449 use them and we're trying to fix the 398 00:14:06,280 --> 00:14:03,949 situation for you but it's a little bit 399 00:14:08,679 --> 00:14:06,290 slow going but it is important not to 400 00:14:11,499 --> 00:14:08,689 forget this because not all organic junk 401 00:14:13,269 --> 00:14:11,509 is the same in particular not all 402 00:14:15,460 --> 00:14:13,279 organic gunk has the same optical 403 00:14:19,449 --> 00:14:15,470 constants so that's just a little 404 00:14:21,220 --> 00:14:19,459 disclaimer and I mention again that it 405 00:14:22,590 --> 00:14:21,230 well no I'm gonna no I'm not gonna skip 406 00:14:24,819 --> 00:14:22,600 this because there's one good answer 407 00:14:26,499 --> 00:14:24,829 this is just a schematic of the 408 00:14:28,119 --> 00:14:26,509 experiment that we're using to do the 409 00:14:30,910 --> 00:14:28,129 exoplanet extract it's just to give you 410 00:14:32,949 --> 00:14:30,920 a slightly more detailed picture we can 411 00:14:34,119 --> 00:14:32,959 do experiments or science 90 p kelvin 412 00:14:36,220 --> 00:14:34,129 i'm going to show you 800 health 413 00:14:37,539 --> 00:14:36,230 experiments today i'm in addition to the 414 00:14:39,669 --> 00:14:37,549 ones that we published we have two 415 00:14:43,239 --> 00:14:39,679 different energy sources and we can do 416 00:14:44,470 --> 00:14:43,249 basically any atmosphere you watch this 417 00:14:47,739 --> 00:14:44,480 is what the chamber looks like when it's 418 00:14:50,379 --> 00:14:47,749 on sorry Caroline I've never seen 419 00:14:51,939 --> 00:14:50,389 someone so excited to see our experiment 420 00:14:54,639 --> 00:14:51,949 I love this picture so much that you 421 00:14:56,980 --> 00:14:54,649 didn't like all of my talks sorry about 422 00:14:58,329 --> 00:14:56,990 that yeah you can come take another one 423 00:15:00,039 --> 00:14:58,339 if you don't like this one but I think 424 00:15:02,019 --> 00:15:00,049 it has to be you at this point 425 00:15:04,239 --> 00:15:02,029 hey that's what the chamber looks like 426 00:15:05,590 --> 00:15:04,249 when it's running with the plasma and 427 00:15:08,109 --> 00:15:05,600 then one thing I wanted to do quickly is 428 00:15:10,090 --> 00:15:08,119 just let you give you a brief list of 429 00:15:12,039 --> 00:15:10,100 the kind of information that we actually 430 00:15:13,569 --> 00:15:12,049 get from laboratory experiments because 431 00:15:14,619 --> 00:15:13,579 I think you know people don't often 432 00:15:17,799 --> 00:15:14,629 think about the price that we can 433 00:15:19,210 --> 00:15:17,809 actually do planetary scientist lab so 434 00:15:20,769 --> 00:15:19,220 we can measure the gas phase products of 435 00:15:22,389 --> 00:15:20,779 these experiments I think this is 436 00:15:23,889 --> 00:15:22,399 particularly important for this audience 437 00:15:26,199 --> 00:15:23,899 because one of the things that we're 438 00:15:28,359 --> 00:15:26,209 hoping to do in the long run if we could 439 00:15:30,460 --> 00:15:28,369 measure the small space products very 440 00:15:31,900 --> 00:15:30,470 precisely these are things you're going 441 00:15:33,760 --> 00:15:31,910 to be able to get if you 442 00:15:35,710 --> 00:15:33,770 haven't already gotten them from things 443 00:15:37,480 --> 00:15:35,720 like James Webb we can measure the small 444 00:15:40,210 --> 00:15:37,490 gases just like you all will have them 445 00:15:41,770 --> 00:15:40,220 too um then we can measure everything 446 00:15:43,390 --> 00:15:41,780 else because we can measure the 447 00:15:44,710 --> 00:15:43,400 particles and so when I'm hoping long 448 00:15:46,870 --> 00:15:44,720 run is that we'll actually be able to 449 00:15:49,060 --> 00:15:46,880 use the lab experiments to tie your 450 00:15:52,150 --> 00:15:49,070 observations together with them with 451 00:15:53,710 --> 00:15:52,160 information we can measure in the lab we 452 00:15:55,060 --> 00:15:53,720 can look at gas to solid conversion if 453 00:15:57,850 --> 00:15:55,070 it's efficiency which is really 454 00:15:59,080 --> 00:15:57,860 important for putting into models we can 455 00:16:00,880 --> 00:15:59,090 measure the composition of the particles 456 00:16:02,710 --> 00:16:00,890 we can measure the particle size 457 00:16:04,870 --> 00:16:02,720 distribution we can measure obstacle 458 00:16:06,190 --> 00:16:04,880 properties we can measure particle 459 00:16:09,040 --> 00:16:06,200 density which is important for cloud 460 00:16:10,960 --> 00:16:09,050 microphysics models we can measure inter 461 00:16:12,430 --> 00:16:10,970 particle forces which are also important 462 00:16:14,920 --> 00:16:12,440 for micro physics we can look at 463 00:16:16,360 --> 00:16:14,930 nucleation efficiency we can do things 464 00:16:18,940 --> 00:16:16,370 like figure out whether or not the 465 00:16:20,710 --> 00:16:18,950 particles will interact happily or sadly 466 00:16:22,690 --> 00:16:20,720 with liquids that might be present in 467 00:16:24,250 --> 00:16:22,700 the atmosphere and if you get really 468 00:16:25,150 --> 00:16:24,260 excited like we do for Titan you can 469 00:16:26,710 --> 00:16:25,160 start thinking about things like 470 00:16:28,360 --> 00:16:26,720 mechanical properties because these 471 00:16:29,680 --> 00:16:28,370 particles might end up seeing the same 472 00:16:31,870 --> 00:16:29,690 students on the planet that you're 473 00:16:33,250 --> 00:16:31,880 interested in and so those are the kinds 474 00:16:36,610 --> 00:16:33,260 of things that lab experiments can 475 00:16:37,930 --> 00:16:36,620 provide you so now I'm gonna actually 476 00:16:40,630 --> 00:16:37,940 show you some real experiments and I 477 00:16:43,090 --> 00:16:40,640 have to apologize in advance because I 478 00:16:46,000 --> 00:16:43,100 made this talk on a Mac and we had some 479 00:16:52,540 --> 00:16:46,010 Mac to PC conversion issues and so some 480 00:16:54,640 --> 00:16:52,550 of my slides looked like modern art was 481 00:16:56,850 --> 00:16:54,650 anybody's time to try to sort it out I 482 00:16:59,710 --> 00:16:56,860 think all the science wives are okay so 483 00:17:01,300 --> 00:16:59,720 one of the things that I first kind of 484 00:17:03,160 --> 00:17:01,310 started getting interested in was trying 485 00:17:05,080 --> 00:17:03,170 to step out of our nitrogen methane box 486 00:17:06,670 --> 00:17:05,090 there are so many nitrogen methane 487 00:17:08,380 --> 00:17:06,680 experiments you all like you have no 488 00:17:10,810 --> 00:17:08,390 idea and so we have spent like 489 00:17:13,330 --> 00:17:10,820 legitimately like 30 or 40 years trying 490 00:17:15,430 --> 00:17:13,340 to study how nitrogen methane form pays 491 00:17:17,350 --> 00:17:15,440 and then basically done nothing else 492 00:17:19,840 --> 00:17:17,360 because we had this one place that we 493 00:17:21,340 --> 00:17:19,850 were interested in and so I first got 494 00:17:24,190 --> 00:17:21,350 interested in trying to understand what 495 00:17:26,860 --> 00:17:24,200 carbon monoxide would do because of 496 00:17:29,080 --> 00:17:26,870 Titan but it turns out that Titan isn't 497 00:17:30,640 --> 00:17:29,090 the only hazy methane nitrogen carbon 498 00:17:32,700 --> 00:17:30,650 oxide atmosphere in the solar system 499 00:17:35,470 --> 00:17:32,710 this is cheating because it's just scale 500 00:17:38,410 --> 00:17:35,480 but that's our friend Titan this one's 501 00:17:40,930 --> 00:17:38,420 Pluto and this is just here in case some 502 00:17:43,180 --> 00:17:40,940 of you have somehow inexplicably never 503 00:17:45,400 --> 00:17:43,190 seen this picture before because 504 00:17:47,260 --> 00:17:45,410 everybody needs to see this picture and 505 00:17:48,550 --> 00:17:47,270 so it was for the solar since the solar 506 00:17:49,900 --> 00:17:48,560 system objects that we first got 507 00:17:51,850 --> 00:17:49,910 interested in trying to understand 508 00:17:53,320 --> 00:17:51,860 carbon monoxide although as we heard 509 00:17:55,510 --> 00:17:53,330 about yesterday carbon monoxide is a 510 00:17:57,160 --> 00:17:55,520 lovely molecule to search for in 511 00:17:58,390 --> 00:17:57,170 exoplanet atmospheres as well and so 512 00:18:00,280 --> 00:17:58,400 this is something that we need to think 513 00:18:02,170 --> 00:18:00,290 about it's also the first oxygen 514 00:18:03,400 --> 00:18:02,180 containing molecule that really start we 515 00:18:05,320 --> 00:18:03,410 really started studying and these 516 00:18:06,850 --> 00:18:05,330 experiments and as you'll see is I 517 00:18:09,280 --> 00:18:06,860 started to talk more about the exoplanet 518 00:18:10,840 --> 00:18:09,290 experiments oxygen bearing molecules 519 00:18:12,940 --> 00:18:10,850 have a really important impact on haze 520 00:18:14,410 --> 00:18:12,950 formation and it really depends which 521 00:18:18,130 --> 00:18:14,420 molecule were talking about what that 522 00:18:19,570 --> 00:18:18,140 impact is so one of the things that we 523 00:18:22,570 --> 00:18:19,580 figured out when we started looking at 524 00:18:24,250 --> 00:18:22,580 Co is that adding co2 these types of 525 00:18:27,370 --> 00:18:24,260 experiments results in an increase in 526 00:18:29,400 --> 00:18:27,380 the in the production rate this happens 527 00:18:33,010 --> 00:18:29,410 for all of the experiments that we did 528 00:18:34,840 --> 00:18:33,020 so we looked at 0.1% methane with a UV 529 00:18:36,880 --> 00:18:34,850 source we looked at 2% methane with the 530 00:18:38,980 --> 00:18:36,890 UV source we switch things up completely 531 00:18:41,410 --> 00:18:38,990 into the same gas mixtures with a plasma 532 00:18:43,000 --> 00:18:41,420 instead just to see if that would have 533 00:18:44,770 --> 00:18:43,010 any effect and the answer was really no 534 00:18:47,200 --> 00:18:44,780 the more carbon monoxide we put into the 535 00:18:49,240 --> 00:18:47,210 experiment the more particles we got 536 00:18:50,950 --> 00:18:49,250 this was really surprising to a lot of 537 00:18:53,440 --> 00:18:50,960 people because we had this idea in our 538 00:18:55,900 --> 00:18:53,450 head that oxygen full-stop whatever 539 00:18:58,360 --> 00:18:55,910 molecule it was contained in was bad for 540 00:19:00,580 --> 00:18:58,370 hay formation and that turned out to 541 00:19:02,110 --> 00:19:00,590 really not be true in fact we have a lot 542 00:19:04,030 --> 00:19:02,120 of reasons now why we think that some 543 00:19:05,320 --> 00:19:04,040 oxygen depending on what molecule it 544 00:19:07,600 --> 00:19:05,330 comes from might actually be really good 545 00:19:10,210 --> 00:19:07,610 for haze formation I'm gonna skip this 546 00:19:12,370 --> 00:19:10,220 slide and it turns out that we could 547 00:19:14,290 --> 00:19:12,380 actually look and see whether this was 548 00:19:17,560 --> 00:19:14,300 from the particles getting bigger which 549 00:19:19,360 --> 00:19:17,570 means that Co makes makes growth more 550 00:19:22,030 --> 00:19:19,370 efficient and it turns out that that's 551 00:19:23,530 --> 00:19:22,040 true the particles get bigger so adding 552 00:19:26,020 --> 00:19:23,540 co2 the gas mixture makes the particles 553 00:19:27,910 --> 00:19:26,030 grow more efficiently but we could also 554 00:19:29,440 --> 00:19:27,920 look at the number density and that 555 00:19:31,390 --> 00:19:29,450 tells us something about the nucleation 556 00:19:33,670 --> 00:19:31,400 efficiency that first step of making a 557 00:19:35,680 --> 00:19:33,680 particle and it turns out that Co also 558 00:19:37,270 --> 00:19:35,690 increases the nucleation efficiency so 559 00:19:41,560 --> 00:19:37,280 this trend we were seeing was a result 560 00:19:43,780 --> 00:19:41,570 of both things and it turns out that one 561 00:19:45,340 --> 00:19:43,790 of the the key things that I think that 562 00:19:47,080 --> 00:19:45,350 we have found from doing this work and 563 00:19:49,360 --> 00:19:47,090 it's relevant for all the exoplanet 564 00:19:51,100 --> 00:19:49,370 stuff is that when we started looking at 565 00:19:52,300 --> 00:19:51,110 the gas phase and the only thing I 566 00:19:55,090 --> 00:19:52,310 actually want you to look at in this 567 00:19:57,250 --> 00:19:55,100 plot are these red diamonds right here 568 00:19:59,210 --> 00:19:57,260 when we started looking at the gas phase 569 00:20:01,730 --> 00:19:59,220 this is a molecular hydrogen 570 00:20:04,850 --> 00:20:01,740 that 2mu point as we put more CEO in the 571 00:20:07,910 --> 00:20:04,860 gas mixture the molecular hydrogen in 572 00:20:09,260 --> 00:20:07,920 the gas phase decreases and we know from 573 00:20:10,610 --> 00:20:09,270 some of the work that's been done for 574 00:20:13,820 --> 00:20:10,620 Titan that the more molecular hydrogen 575 00:20:15,950 --> 00:20:13,830 is present the less efficient particle 576 00:20:17,930 --> 00:20:15,960 formation is because every time you 577 00:20:20,060 --> 00:20:17,940 break one of those carbon hydrogen bonds 578 00:20:21,650 --> 00:20:20,070 to try to build a bigger molecule you 579 00:20:23,600 --> 00:20:21,660 have the opportunity to molecular 580 00:20:25,610 --> 00:20:23,610 hydrogen and just reform that bond so 581 00:20:27,800 --> 00:20:25,620 getting rid of the molecular hydrogen is 582 00:20:30,020 --> 00:20:27,810 really important to make hey its 583 00:20:32,120 --> 00:20:30,030 formation more efficient and having 584 00:20:34,250 --> 00:20:32,130 oxygen in the gas mixture that came from 585 00:20:36,230 --> 00:20:34,260 that Co seems to be pulling some of that 586 00:20:40,550 --> 00:20:36,240 hydrogen out and forming other molecules 587 00:20:41,660 --> 00:20:40,560 which helps increase the efficiency one 588 00:20:43,310 --> 00:20:41,670 other thing we learned from looking at 589 00:20:44,960 --> 00:20:43,320 the solids is that the oxygen actually 590 00:20:46,610 --> 00:20:44,970 really participates in the chemistry and 591 00:20:49,220 --> 00:20:46,620 so the more Co we put in the gas mixture 592 00:20:51,380 --> 00:20:49,230 the more oxygen-rich the aerosol is and 593 00:20:53,390 --> 00:20:51,390 so this tells us something right away 594 00:20:54,650 --> 00:20:53,400 which is that the optical properties of 595 00:20:56,000 --> 00:20:54,660 these particles are almost certainly 596 00:20:57,830 --> 00:20:56,010 changing their composition is very 597 00:20:59,060 --> 00:20:57,840 different that's going to affect all of 598 00:21:00,320 --> 00:20:59,070 the ways in which they're interacting 599 00:21:03,770 --> 00:21:00,330 with the atmosphere and so this is 600 00:21:05,450 --> 00:21:03,780 really important we also decided to look 601 00:21:08,270 --> 00:21:05,460 to see what kinds of oxygen molecules 602 00:21:09,530 --> 00:21:08,280 and since we have some some astrobiology 603 00:21:11,000 --> 00:21:09,540 interest in this crowd I just thought I 604 00:21:12,200 --> 00:21:11,010 would quickly point this out that we've 605 00:21:14,660 --> 00:21:12,210 seen that you can make a lot of 606 00:21:16,880 --> 00:21:14,670 molecules of astrobiological interest in 607 00:21:18,590 --> 00:21:16,890 the gas phase in experiments that 608 00:21:20,510 --> 00:21:18,600 include Co so these are the five 609 00:21:23,180 --> 00:21:20,520 nucleobases that all of life on Earth 610 00:21:26,780 --> 00:21:23,190 uses and the two smallest protein a 611 00:21:30,260 --> 00:21:26,790 Jenica amino acid and a glycine and 612 00:21:31,340 --> 00:21:30,270 alanine I'm gonna skip that slide one of 613 00:21:33,230 --> 00:21:31,350 the other things we've discovered more 614 00:21:35,300 --> 00:21:33,240 recently which i think is also really 615 00:21:36,710 --> 00:21:35,310 relevant to thinking about this issue of 616 00:21:39,080 --> 00:21:36,720 where haze formation occurs in different 617 00:21:41,060 --> 00:21:39,090 atmospheres is that we found that the 618 00:21:43,070 --> 00:21:41,070 more energetic environment in our lab 619 00:21:45,050 --> 00:21:43,080 experiments produces more prebiotic 620 00:21:47,000 --> 00:21:45,060 molecules so these are two different 621 00:21:49,430 --> 00:21:47,010 energy sources one of them is a plasma 622 00:21:51,140 --> 00:21:49,440 and one of them is a UV source otherwise 623 00:21:53,150 --> 00:21:51,150 the experiments are effectively the same 624 00:21:55,160 --> 00:21:53,160 you can see just from looking at how 625 00:21:57,050 --> 00:21:55,170 many things are labeled in this column 626 00:21:59,030 --> 00:21:57,060 versus this column that we're seeing a 627 00:22:01,190 --> 00:21:59,040 lot more of these molecules when we use 628 00:22:03,770 --> 00:22:01,200 the plasma energy source that energy 629 00:22:05,540 --> 00:22:03,780 source is much more analogous for the 630 00:22:07,520 --> 00:22:05,550 upper atmosphere of a planet when we're 631 00:22:09,050 --> 00:22:07,530 in the ionosphere and so that's a place 632 00:22:11,660 --> 00:22:09,060 for some really interesting chemistry to 633 00:22:13,130 --> 00:22:11,670 happen so just to give you a quick 634 00:22:15,440 --> 00:22:13,140 summary about what we learned about sea 635 00:22:16,789 --> 00:22:15,450 the particle size number densities are 636 00:22:19,430 --> 00:22:16,799 for the total amount of stuff that we 637 00:22:21,860 --> 00:22:19,440 made increases when we put Co in the in 638 00:22:23,480 --> 00:22:21,870 the experiments it decreases the gas 639 00:22:26,150 --> 00:22:23,490 phase molecular hydrogen I think that's 640 00:22:28,490 --> 00:22:26,160 really key to what's happening in terms 641 00:22:30,230 --> 00:22:28,500 of the production rate the aerosols 642 00:22:32,720 --> 00:22:30,240 become more oxygen-rich as we put more 643 00:22:34,310 --> 00:22:32,730 co in the gas mixture and we also get 644 00:22:36,169 --> 00:22:34,320 some production of some some molecules 645 00:22:37,400 --> 00:22:36,179 prebiotic interest which is a really 646 00:22:38,720 --> 00:22:37,410 interesting and has important 647 00:22:40,970 --> 00:22:38,730 implications for the role that haze 648 00:22:44,090 --> 00:22:40,980 might play in the origin or evolution of 649 00:22:45,409 --> 00:22:44,100 life so after that we got really excited 650 00:22:48,409 --> 00:22:45,419 about exoplanets cuz when everybody was 651 00:22:50,419 --> 00:22:48,419 getting excited about exoplanets so we 652 00:22:52,789 --> 00:22:50,429 and we gotta figure out where to start 653 00:22:55,610 --> 00:22:52,799 because there's a lot of them I think 654 00:22:58,250 --> 00:22:55,620 you all sympathize with that feeling and 655 00:22:59,810 --> 00:22:58,260 so we decided to focus on this class of 656 00:23:02,090 --> 00:22:59,820 planets that we apparently don't have in 657 00:23:03,890 --> 00:23:02,100 our solar system super simony them one 658 00:23:05,360 --> 00:23:03,900 of the reasons that we did that aside 659 00:23:07,850 --> 00:23:05,370 from the fact that there's so many of 660 00:23:10,039 --> 00:23:07,860 them is that I wanted to play with new 661 00:23:13,789 --> 00:23:10,049 molecules and so I needed new kinds of 662 00:23:15,919 --> 00:23:13,799 planets and so this is one of the 663 00:23:18,470 --> 00:23:15,929 reasons why the other reason why I think 664 00:23:20,780 --> 00:23:18,480 many of you know know and potentially 665 00:23:23,570 --> 00:23:20,790 hate everyone's favorite problem child 666 00:23:25,549 --> 00:23:23,580 GJ 1214b but it was also the the period 667 00:23:26,900 --> 00:23:25,559 of time when a lot of the supers and 668 00:23:28,730 --> 00:23:26,910 many Neptune's that we weren't able to 669 00:23:30,289 --> 00:23:28,740 get observations up we're turning up 670 00:23:31,549 --> 00:23:30,299 with some kite type of particle in their 671 00:23:35,210 --> 00:23:31,559 atmospheres whether it was paid for 672 00:23:37,280 --> 00:23:35,220 clouds so we decided to focus on this 673 00:23:38,659 --> 00:23:37,290 phase space where we could really look 674 00:23:42,370 --> 00:23:38,669 at the effect of a lot of different 675 00:23:45,500 --> 00:23:42,380 molecules so we started with this matrix 676 00:23:49,010 --> 00:23:45,510 we did experiments at 300 400 and 600 677 00:23:52,039 --> 00:23:49,020 Kelvin at a hundred a thousand and ten 678 00:23:54,049 --> 00:23:52,049 thousand times solar metallicity which 679 00:23:55,430 --> 00:23:54,059 in this audience is probably an OK unit 680 00:23:58,159 --> 00:23:55,440 cheese but you can also think of them as 681 00:24:01,520 --> 00:23:58,169 being hydrogen rich water rich or co2 682 00:24:03,049 --> 00:24:01,530 rich we started with equilibrium 683 00:24:06,680 --> 00:24:03,059 calculations that were done by Julie 684 00:24:08,390 --> 00:24:06,690 Moses we don't actually yet have good 685 00:24:09,680 --> 00:24:08,400 measurements to start from to do these 686 00:24:11,000 --> 00:24:09,690 experiments like we do in the solar 687 00:24:14,150 --> 00:24:11,010 system so we thought this was a good 688 00:24:15,890 --> 00:24:14,160 good starting point and what we found 689 00:24:19,010 --> 00:24:15,900 was that we get all kinds of production 690 00:24:20,060 --> 00:24:19,020 rates so the interesting case there's a 691 00:24:22,419 --> 00:24:20,070 bunch of interesting cases to me 692 00:24:23,769 --> 00:24:22,429 actually the 693 00:24:25,509 --> 00:24:23,779 timeis metallicity experiments were 694 00:24:27,519 --> 00:24:25,519 really interesting to us because of the 695 00:24:29,769 --> 00:24:27,529 following thing this grey line right 696 00:24:32,409 --> 00:24:29,779 here is our standard tighten production 697 00:24:34,090 --> 00:24:32,419 rate in our experiment so two of our 698 00:24:36,340 --> 00:24:34,100 experiments are actually have a higher 699 00:24:38,049 --> 00:24:36,350 production rate than tighten which was 700 00:24:39,310 --> 00:24:38,059 fascinating to us I don't think we ever 701 00:24:41,109 --> 00:24:39,320 in a million years thought any of these 702 00:24:42,850 --> 00:24:41,119 gas mixtures would make particles better 703 00:24:47,200 --> 00:24:42,860 than tighten make particles but we were 704 00:24:48,879 --> 00:24:47,210 wrong one of the things that these two 705 00:24:50,919 --> 00:24:48,889 experiments have in common is that they 706 00:24:53,739 --> 00:24:50,929 have quite a bit of methane in them but 707 00:24:55,989 --> 00:24:53,749 they also have a lot of water in the gas 708 00:24:57,519 --> 00:24:55,999 phase and so we weren't really sure how 709 00:24:59,859 --> 00:24:57,529 water was going to be interacting with 710 00:25:01,930 --> 00:24:59,869 the chemistry it has oxygen in it and 711 00:25:03,700 --> 00:25:01,940 we're still working to sort a lot of the 712 00:25:07,869 --> 00:25:03,710 details of this out this didn't really 713 00:25:09,820 --> 00:25:07,879 surprise me at all actually um in part 714 00:25:11,889 --> 00:25:09,830 because we know from the solar system 715 00:25:13,810 --> 00:25:11,899 and we know from previous experiments 716 00:25:15,340 --> 00:25:13,820 that molecular hydrogen dominated gas 717 00:25:17,859 --> 00:25:15,350 mixtures just aren't as efficient at 718 00:25:19,539 --> 00:25:17,869 producing case we do see particles in 719 00:25:21,009 --> 00:25:19,549 our experiment we also see Hayes's 720 00:25:22,779 --> 00:25:21,019 Jupiter's atmosphere and Saturn's 721 00:25:24,369 --> 00:25:22,789 atmosphere they're just not great places 722 00:25:28,090 --> 00:25:24,379 from doing this type of chemistry 723 00:25:30,519 --> 00:25:28,100 because of the hydrogen this this over 724 00:25:32,019 --> 00:25:30,529 here I still don't understand this 725 00:25:35,470 --> 00:25:32,029 experiment has no methane in it 726 00:25:36,970 --> 00:25:35,480 whatsoever and still managed to convert 727 00:25:38,739 --> 00:25:36,980 some of the carbon monoxide that was in 728 00:25:41,409 --> 00:25:38,749 the gas phase into a solid that contains 729 00:25:43,509 --> 00:25:41,419 carbon which is amazing and so what I 730 00:25:45,220 --> 00:25:43,519 wanted to you to get out of this plot 731 00:25:47,200 --> 00:25:45,230 what I'm going to tell you more as we go 732 00:25:49,539 --> 00:25:47,210 along is that there are many pathways to 733 00:25:51,430 --> 00:25:49,549 making haze there are many pathways to 734 00:25:52,960 --> 00:25:51,440 similar production rates these three 735 00:25:54,909 --> 00:25:52,970 experiments have very similar production 736 00:25:58,269 --> 00:25:54,919 rates and have completely different 737 00:26:00,009 --> 00:25:58,279 chemistry happening we did the same 738 00:26:02,889 --> 00:26:00,019 thing with the UV source we saw a 739 00:26:05,230 --> 00:26:02,899 similar trend in particular this 300 740 00:26:07,119 --> 00:26:05,240 Kelvin thousand times solar metallicity 741 00:26:09,450 --> 00:26:07,129 experiment just really wants to make 742 00:26:11,529 --> 00:26:09,460 particles it's super excited about it 743 00:26:13,359 --> 00:26:11,539 another thing that we found is that the 744 00:26:15,129 --> 00:26:13,369 color of the particle is actually varies 745 00:26:17,440 --> 00:26:15,139 quite a bit depending on what gas 746 00:26:19,629 --> 00:26:17,450 mixture we're looking at I have never 747 00:26:22,180 --> 00:26:19,639 ever seen a lab experiment produce 748 00:26:23,350 --> 00:26:22,190 particles of these two colors we decided 749 00:26:25,299 --> 00:26:23,360 that's olive green and this this 750 00:26:27,070 --> 00:26:25,309 chocolate brown I don't know if I'm not 751 00:26:28,960 --> 00:26:27,080 speeding my research group enough or 752 00:26:30,310 --> 00:26:28,970 what one of my grad students didn't read 753 00:26:33,789 --> 00:26:30,320 that I can't tell she which direction 754 00:26:35,409 --> 00:26:33,799 she sees shaking her head these two 755 00:26:36,100 --> 00:26:35,419 experiments with the similar production 756 00:26:38,680 --> 00:26:36,110 rates 757 00:26:40,900 --> 00:26:38,690 to tighten also looks suspiciously 758 00:26:42,700 --> 00:26:40,910 tighten color although again I have to 759 00:26:45,070 --> 00:26:42,710 tell you their composition is completely 760 00:26:46,660 --> 00:26:45,080 different and if you want to know more 761 00:26:50,230 --> 00:26:46,670 about the composition you should go see 762 00:26:52,480 --> 00:26:50,240 Sarah Moran's poster today and so we 763 00:26:53,920 --> 00:26:52,490 know the color varies we also know that 764 00:26:55,690 --> 00:26:53,930 the particle diameter varies in 765 00:26:57,010 --> 00:26:55,700 particular the 10,000 times metallicity 766 00:26:59,020 --> 00:26:57,020 experiments like to make much larger 767 00:27:03,220 --> 00:26:59,030 particles than we were seeing with the 768 00:27:04,810 --> 00:27:03,230 other experiments and finally we looked 769 00:27:07,120 --> 00:27:04,820 at the gas phase I promised you we would 770 00:27:10,240 --> 00:27:07,130 do that and we did this is a very busy 771 00:27:11,440 --> 00:27:10,250 plot so you can just listen to me while 772 00:27:13,270 --> 00:27:11,450 I walk you through it for a second this 773 00:27:15,820 --> 00:27:13,280 is all of the experiments I just showed 774 00:27:19,180 --> 00:27:15,830 you so all of the gas mixtures all the 775 00:27:20,860 --> 00:27:19,190 metallicity both energy sources and the 776 00:27:23,110 --> 00:27:20,870 first thing to see is that in every 777 00:27:24,990 --> 00:27:23,120 single experiment we produce organic 778 00:27:27,310 --> 00:27:25,000 molecules in the gas phase all of them 779 00:27:30,250 --> 00:27:27,320 including the one that didn't have any 780 00:27:33,610 --> 00:27:30,260 methane in it to begin with so that was 781 00:27:35,350 --> 00:27:33,620 kind of impressive in quite a few of 782 00:27:37,830 --> 00:27:35,360 them we've produced what we have 783 00:27:40,210 --> 00:27:37,840 described as prebiotic precursors 784 00:27:41,470 --> 00:27:40,220 molecules that the prebiotic chemistry 785 00:27:42,970 --> 00:27:41,480 community tends to think of as being 786 00:27:44,290 --> 00:27:42,980 important precursors things like 787 00:27:46,330 --> 00:27:44,300 hydrogen cyanide things like 788 00:27:48,160 --> 00:27:46,340 formaldehyde on these kind of small 789 00:27:51,580 --> 00:27:48,170 organic molecules that can then slimmer 790 00:27:53,530 --> 00:27:51,590 eyes or participate in other chemistry 791 00:27:55,270 --> 00:27:53,540 and then finally the things that are 792 00:27:58,990 --> 00:27:55,280 stars we actually produced a molecular 793 00:28:01,900 --> 00:27:59,000 oxygen in the gas phase and just to note 794 00:28:03,880 --> 00:28:01,910 that in all of those cases we saw 795 00:28:06,370 --> 00:28:03,890 molecular nitrogen alekhya leur oxygen 796 00:28:08,560 --> 00:28:06,380 in the presence of both these prebiotic 797 00:28:10,330 --> 00:28:08,570 precursor molecules that some people 798 00:28:13,180 --> 00:28:10,340 might also think about as biomarkers and 799 00:28:15,610 --> 00:28:13,190 organics and so that's just something 800 00:28:17,710 --> 00:28:15,620 that we need to think really hard about 801 00:28:19,420 --> 00:28:17,720 in terms of our understanding going 802 00:28:21,820 --> 00:28:19,430 forward of what of what atmospheres are 803 00:28:24,520 --> 00:28:21,830 capable of and so just to give you a 804 00:28:26,230 --> 00:28:24,530 quick summary of those experiments we 805 00:28:28,990 --> 00:28:26,240 found that the water the water rich or 806 00:28:31,030 --> 00:28:29,000 water dominated cases produce the most 807 00:28:32,590 --> 00:28:31,040 particles Titan like amounts of 808 00:28:34,690 --> 00:28:32,600 particles we know that they're different 809 00:28:35,770 --> 00:28:34,700 colors and so we can tell just by 810 00:28:38,490 --> 00:28:35,780 looking that they're going to have 811 00:28:40,540 --> 00:28:38,500 different different optical properties 812 00:28:42,160 --> 00:28:40,550 we also know that metallicity and 813 00:28:43,870 --> 00:28:42,170 temperature both appear to matter the 814 00:28:45,430 --> 00:28:43,880 way we built this matrix is a little 815 00:28:46,780 --> 00:28:45,440 hard to think about metallicity and 816 00:28:49,630 --> 00:28:46,790 temperature because each of those 817 00:28:51,250 --> 00:28:49,640 experiments is self-consistent we had to 818 00:28:53,140 --> 00:28:51,260 the gas is an equilibrium to start 819 00:28:56,680 --> 00:28:53,150 otherwise we wouldn't have any idea what 820 00:28:57,970 --> 00:28:56,690 we were actually irradiating and so 821 00:29:00,010 --> 00:28:57,980 because of that as you change the 822 00:29:01,330 --> 00:29:00,020 metallicity as you change the 823 00:29:02,530 --> 00:29:01,340 temperature also changing the gas 824 00:29:04,180 --> 00:29:02,540 mixture as you change the metallicity 825 00:29:05,560 --> 00:29:04,190 you're also changing the gas mixture and 826 00:29:07,030 --> 00:29:05,570 so each of those is a discrete gas 827 00:29:09,100 --> 00:29:07,040 mixture so it's a little hard to study 828 00:29:11,760 --> 00:29:09,110 trend but they both seem to have an 829 00:29:14,410 --> 00:29:11,770 effect on what's happening in the 830 00:29:15,820 --> 00:29:14,420 experiment and also we see molecular 831 00:29:19,360 --> 00:29:15,830 oxygen and organics produced 832 00:29:22,030 --> 00:29:19,370 simultaneously in the gas phase so this 833 00:29:23,650 --> 00:29:22,040 is the matrix that we started with and 834 00:29:25,960 --> 00:29:23,660 this is the one that we have published 835 00:29:28,299 --> 00:29:25,970 thus far everything that I just showed 836 00:29:30,250 --> 00:29:28,309 you I'm gonna make the following request 837 00:29:32,530 --> 00:29:30,260 because I want to show you stuff that's 838 00:29:33,850 --> 00:29:32,540 new I realize this is being broadcast so 839 00:29:35,080 --> 00:29:33,860 it feels a little ridiculous but also 840 00:29:36,880 --> 00:29:35,090 those of you who are being broadcast 841 00:29:39,490 --> 00:29:36,890 please don't screenshot or tweet about 842 00:29:41,020 --> 00:29:39,500 my talk thank you please no pictures 843 00:29:43,750 --> 00:29:41,030 please no tweeting and especially no 844 00:29:46,450 --> 00:29:43,760 tweets with pictures thank you okay so 845 00:29:48,789 --> 00:29:46,460 we have been doing experiments at 800 846 00:29:50,140 --> 00:29:48,799 Kelvin um these are the gas mixtures for 847 00:29:52,150 --> 00:29:50,150 the a hundred Kelvin experiments I'm 848 00:29:54,940 --> 00:29:52,160 going to leave you wondering what 849 00:29:57,880 --> 00:29:54,950 happened in these two and focus entirely 850 00:29:59,950 --> 00:29:57,890 on this experiment right here um once we 851 00:30:01,750 --> 00:29:59,960 got up to 800 Kelvin at 10,000 times 852 00:30:04,600 --> 00:30:01,760 solar medalists equilibrium there's a 853 00:30:06,940 --> 00:30:04,610 hydrogen sulfide in the gas mixture and 854 00:30:10,419 --> 00:30:06,950 so we wanted to find out what happens 855 00:30:12,460 --> 00:30:10,429 with sulfur and so we ran these if this 856 00:30:15,880 --> 00:30:12,470 gas mixture that you see right here with 857 00:30:18,010 --> 00:30:15,890 h2s with both the plasma and the UV the 858 00:30:19,750 --> 00:30:18,020 way that we've done in the past but we 859 00:30:21,340 --> 00:30:19,760 also did experiments where we swapped 860 00:30:23,560 --> 00:30:21,350 out the height of the hydrogen sulfide 861 00:30:25,990 --> 00:30:23,570 with argon which is inert it won't do 862 00:30:29,310 --> 00:30:26,000 anything just to see what the impact of 863 00:30:32,110 --> 00:30:29,320 adding that h2s was on these experiments 864 00:30:34,360 --> 00:30:32,120 so what we find is that the presence of 865 00:30:37,090 --> 00:30:34,370 hydrogen sulfide increases the particle 866 00:30:40,960 --> 00:30:37,100 production rate in both the plasma and 867 00:30:43,750 --> 00:30:40,970 the UV this is a skinning an electron no 868 00:30:45,039 --> 00:30:43,760 atomic force microscope image of the 869 00:30:46,510 --> 00:30:45,049 disks that are sitting on the bottom of 870 00:30:49,000 --> 00:30:46,520 the chamber that we use for some of our 871 00:30:50,680 --> 00:30:49,010 other measurements you can see what the 872 00:30:54,370 --> 00:30:50,690 plasma that the particle size increased 873 00:30:55,720 --> 00:30:54,380 pretty dramatically too with the UV the 874 00:30:58,030 --> 00:30:55,730 particle the average particle size 875 00:30:59,650 --> 00:30:58,040 didn't actually change that much but the 876 00:31:01,390 --> 00:30:59,660 size distribution changed quite a bit 877 00:31:01,960 --> 00:31:01,400 and also you can see for yourself there 878 00:31:03,730 --> 00:31:01,970 are way more 879 00:31:07,920 --> 00:31:03,740 articles with the h2s them there are way 880 00:31:10,630 --> 00:31:07,930 about I cut off the blank but a blank 881 00:31:12,310 --> 00:31:10,640 disk from our experiment looks like 882 00:31:15,550 --> 00:31:12,320 completely flat there's not a single 883 00:31:16,990 --> 00:31:15,560 particle on it until the presence of h2s 884 00:31:19,510 --> 00:31:17,000 increases the particle production rate 885 00:31:20,500 --> 00:31:19,520 here's the actual measurements just to 886 00:31:22,360 --> 00:31:20,510 give you a sense of how much it's 887 00:31:26,260 --> 00:31:22,370 changing it's pretty substantial 888 00:31:27,520 --> 00:31:26,270 actually so we're you know interested in 889 00:31:29,260 --> 00:31:27,530 trying to understand the sulfur 890 00:31:30,880 --> 00:31:29,270 chemistry more putting that in the 891 00:31:32,410 --> 00:31:30,890 context of the previous work that we've 892 00:31:35,410 --> 00:31:32,420 done this is the plot I showed you with 893 00:31:37,540 --> 00:31:35,420 the original nine plasma experiments and 894 00:31:39,550 --> 00:31:37,550 I've now put the eight hundred Kelvin 895 00:31:42,670 --> 00:31:39,560 experiment on here in a color that 896 00:31:43,660 --> 00:31:42,680 apparently no one can see it goes like 897 00:31:45,130 --> 00:31:43,670 goes right over here 898 00:31:48,220 --> 00:31:45,140 just it looks it's at the bottom of the 899 00:31:51,310 --> 00:31:48,230 K if you can't see it so the interesting 900 00:31:52,930 --> 00:31:51,320 thing that I noticed now when I look at 901 00:31:54,250 --> 00:31:52,940 this plot having added this additional 902 00:31:57,220 --> 00:31:54,260 data point and also knowing what the 903 00:31:59,650 --> 00:31:57,230 answer is for these other suitcases is 904 00:32:01,360 --> 00:31:59,660 that it appears that in the 10,000 times 905 00:32:02,830 --> 00:32:01,370 metallicity case as we increase 906 00:32:05,260 --> 00:32:02,840 temperature were actually increasing 907 00:32:07,000 --> 00:32:05,270 production rate just the opposite of 908 00:32:10,420 --> 00:32:07,010 what's happening and the other two 909 00:32:12,070 --> 00:32:10,430 metallicity that is almost entirely to 910 00:32:14,710 --> 00:32:12,080 do with this addition of these extra 911 00:32:17,680 --> 00:32:14,720 gases that we weren't using at the lower 912 00:32:19,030 --> 00:32:17,690 temperatures and I think that's really 913 00:32:21,100 --> 00:32:19,040 interesting and there's a lot more work 914 00:32:23,860 --> 00:32:21,110 to do the presence of hydrogen sulfide 915 00:32:26,020 --> 00:32:23,870 doesn't actually substantially affect 916 00:32:28,480 --> 00:32:26,030 the total amount of gas based products 917 00:32:30,340 --> 00:32:28,490 but what it does is it really decreases 918 00:32:32,800 --> 00:32:30,350 the amount of molecular oxygen present 919 00:32:34,810 --> 00:32:32,810 in the gas phase and I assume that 920 00:32:36,520 --> 00:32:34,820 that's partially that's in part due to 921 00:32:38,140 --> 00:32:36,530 the fact that the sulfur is pulling that 922 00:32:40,900 --> 00:32:38,150 out and having it participate in the 923 00:32:42,370 --> 00:32:40,910 chemistry we see all kinds of 924 00:32:45,610 --> 00:32:42,380 interesting molecules in the gas phase 925 00:32:48,160 --> 00:32:45,620 we see our favorite precursors hydrogen 926 00:32:50,350 --> 00:32:48,170 cyanide and formaldehyde we see two 927 00:32:51,820 --> 00:32:50,360 nitrile then we see a whole bunch of 928 00:32:55,330 --> 00:32:51,830 sulfur containing molecules the gas 929 00:32:57,390 --> 00:32:55,340 phase so we see methyl mercaptan which 930 00:32:59,620 --> 00:32:57,400 is well known for smelling delicious 931 00:33:02,350 --> 00:32:59,630 that was sarcasm for those of you who 932 00:33:05,680 --> 00:33:02,360 don't know what my captains are we see 933 00:33:08,500 --> 00:33:05,690 sulfur oxide we see carbonyl sulfide we 934 00:33:10,750 --> 00:33:08,510 see ethylene sulfide we see so2 we see 935 00:33:12,460 --> 00:33:10,760 carbon disulfide we see the sulfur 936 00:33:15,010 --> 00:33:12,470 really participating in the gas phase 937 00:33:15,550 --> 00:33:15,020 chemistry not seeming to have much of an 938 00:33:19,150 --> 00:33:15,560 effect 939 00:33:22,030 --> 00:33:19,160 the amount of molecular oxygen present 940 00:33:24,700 --> 00:33:22,040 in the gas phase so we're still working 941 00:33:26,500 --> 00:33:24,710 on trying to understand this and we'll 942 00:33:28,420 --> 00:33:26,510 be finishing working up the other two 943 00:33:30,670 --> 00:33:28,430 experiments this paper will hopefully be 944 00:33:32,710 --> 00:33:30,680 submitted next week so those of you who 945 00:33:34,000 --> 00:33:32,720 have been dying for sulfur experiments 946 00:33:34,770 --> 00:33:34,010 we finally did one for you you're 947 00:33:36,790 --> 00:33:34,780 welcome 948 00:33:38,350 --> 00:33:36,800 so we found that the presence of 949 00:33:40,570 --> 00:33:38,360 hydrogen sulfide increases production 950 00:33:43,030 --> 00:33:40,580 right the pressure of gas phase organics 951 00:33:45,600 --> 00:33:43,040 is relatively unaffected but the o2 was 952 00:33:47,680 --> 00:33:45,610 changing pretty pretty dramatically and 953 00:33:49,210 --> 00:33:47,690 for the 10,000 times metallicity 954 00:33:50,860 --> 00:33:49,220 experiments the production rate appears 955 00:33:52,510 --> 00:33:50,870 to increase as a function of increasing 956 00:33:53,980 --> 00:33:52,520 temperature which we think is the 957 00:33:57,040 --> 00:33:53,990 opposite of what's happening with the 958 00:33:59,350 --> 00:33:57,050 other two metallicity x' and so that 959 00:34:01,690 --> 00:33:59,360 just goes to show that the composition 960 00:34:03,670 --> 00:34:01,700 of the gases in your experiment really 961 00:34:06,010 --> 00:34:03,680 matters in terms of what kinds of 962 00:34:07,570 --> 00:34:06,020 particles there are and how many but 963 00:34:10,210 --> 00:34:07,580 that also shows that there are so many 964 00:34:11,980 --> 00:34:10,220 different pathways for haze formation so 965 00:34:13,870 --> 00:34:11,990 real quick just to say what's next for 966 00:34:15,370 --> 00:34:13,880 these experiments I mentioned that you 967 00:34:17,440 --> 00:34:15,380 can go see some of the particle 968 00:34:19,810 --> 00:34:17,450 composition results unfortunately not 969 00:34:22,690 --> 00:34:19,820 the sulphur ones you had the the rest of 970 00:34:24,100 --> 00:34:22,700 the matrix is on Sara's post or at least 971 00:34:25,690 --> 00:34:24,110 the ones that cooperated with our 972 00:34:29,889 --> 00:34:25,700 measurement techniques which was not all 973 00:34:30,760 --> 00:34:29,899 of them she's shaking her head yeah and 974 00:34:32,470 --> 00:34:30,770 then the other thing we're gonna be 975 00:34:34,270 --> 00:34:32,480 doing for these is optical constants 976 00:34:36,310 --> 00:34:34,280 measurement so we'll actually do 977 00:34:38,520 --> 00:34:36,320 measurements in the UV too but the 978 00:34:40,960 --> 00:34:38,530 interwebz showing you right here can do 979 00:34:42,909 --> 00:34:40,970 optical constants from 400 nanometers to 980 00:34:44,440 --> 00:34:42,919 25 microns and we're gonna be doing the 981 00:34:47,649 --> 00:34:44,450 measurements at the temperature that the 982 00:34:50,380 --> 00:34:47,659 experiment was run because we have a 983 00:34:53,770 --> 00:34:50,390 cryostat on our instrument that can do 984 00:34:55,480 --> 00:34:53,780 from 3 to 800 Kelvin and try explaining 985 00:34:57,070 --> 00:34:55,490 to a Christ company why you want to 986 00:34:59,560 --> 00:34:57,080 Christ out that goes from 3 to 800 987 00:35:03,010 --> 00:34:59,570 Kelvin I just want to do a whole solar 988 00:35:04,570 --> 00:35:03,020 system not too much to ask and so we'll 989 00:35:08,020 --> 00:35:04,580 be doing those a temperature hopefully 990 00:35:10,120 --> 00:35:08,030 that'll be done sometime around the 991 00:35:11,800 --> 00:35:10,130 beginning of next year and so we'll have 992 00:35:17,560 --> 00:35:11,810 optic optical constants from these 993 00:35:20,140 --> 00:35:17,570 particles as well sorry 994 00:35:21,640 --> 00:35:20,150 so I talked to you about experiments 995 00:35:24,760 --> 00:35:21,650 with carbon monoxide I talked you about 996 00:35:26,140 --> 00:35:24,770 experiments with water with co2 and so 997 00:35:27,850 --> 00:35:26,150 that's like a good chunk of our oxygen 998 00:35:29,420 --> 00:35:27,860 containing molecules which I was really 999 00:35:31,760 --> 00:35:29,430 interested in 1000 00:35:33,050 --> 00:35:31,770 but I also wanted to go all the way all 1001 00:35:35,540 --> 00:35:33,060 the way to that to the edge of the 1002 00:35:36,890 --> 00:35:35,550 oxidation states and so a couple years 1003 00:35:38,930 --> 00:35:36,900 ago I did some experiments with 1004 00:35:41,570 --> 00:35:38,940 molecular oxygen ray and I collaborated 1005 00:35:43,700 --> 00:35:41,580 on this paper to try to actually think 1006 00:35:45,650 --> 00:35:43,710 about what was happening in the early 1007 00:35:47,599 --> 00:35:45,660 Earth which we heard of some a little 1008 00:35:49,099 --> 00:35:47,609 bit about this morning but this is also 1009 00:35:50,570 --> 00:35:49,109 relevant for thinking about extrasolar 1010 00:35:53,480 --> 00:35:50,580 planets in terms of what might happen 1011 00:35:56,570 --> 00:35:53,490 either in atmospheres that have a 1012 00:35:58,099 --> 00:35:56,580 nascent biosphere on their surface or 1013 00:35:59,570 --> 00:35:58,109 thinking about what happens when you 1014 00:36:02,630 --> 00:35:59,580 might see the signal of molecular oxygen 1015 00:36:03,740 --> 00:36:02,640 in an atmosphere so we wanted to know if 1016 00:36:06,050 --> 00:36:03,750 haze could exist during the rise of 1017 00:36:08,240 --> 00:36:06,060 oxygen so this is an early early Earth 1018 00:36:10,450 --> 00:36:08,250 this is like things have started making 1019 00:36:13,490 --> 00:36:10,460 oxygen there's just not a lot of it yet 1020 00:36:14,720 --> 00:36:13,500 and part of the reason again that I was 1021 00:36:16,580 --> 00:36:14,730 interested in trying to do this is 1022 00:36:18,560 --> 00:36:16,590 because we have this idea that oxidized 1023 00:36:21,950 --> 00:36:18,570 atmospheres are less favorable for 1024 00:36:23,900 --> 00:36:21,960 photochemical haze production um and as 1025 00:36:25,370 --> 00:36:23,910 I think I've already shown you not all 1026 00:36:27,170 --> 00:36:25,380 is it all not all oxygen bearing 1027 00:36:29,150 --> 00:36:27,180 molecules are this and so we wanted to 1028 00:36:30,920 --> 00:36:29,160 figure out what happened with o2 this 1029 00:36:32,780 --> 00:36:30,930 next plot is super complicated so I'm 1030 00:36:34,520 --> 00:36:32,790 going to step you through it before just 1031 00:36:37,760 --> 00:36:34,530 throwing the whole thing at you at the 1032 00:36:39,800 --> 00:36:37,770 end so this is this set of experiments 1033 00:36:41,900 --> 00:36:39,810 right here only have methane and 1034 00:36:44,180 --> 00:36:41,910 nitrogen there's no oxygen containing 1035 00:36:47,390 --> 00:36:44,190 molecules new experiment these are the 1036 00:36:49,490 --> 00:36:47,400 methane abundances and you can see the 1037 00:36:51,740 --> 00:36:49,500 production rates there you know doing 1038 00:36:54,500 --> 00:36:51,750 their thing they're doing a well known 1039 00:36:56,480 --> 00:36:54,510 thing in fact we know that in the lab 1040 00:36:59,060 --> 00:36:56,490 with a UV source which is what we're 1041 00:37:00,770 --> 00:36:59,070 using that most people see that there's 1042 00:37:02,270 --> 00:37:00,780 a peak in the aerosol production rate 1043 00:37:05,480 --> 00:37:02,280 somewhere around point one percent 1044 00:37:08,000 --> 00:37:05,490 methane before it turns back over we 1045 00:37:09,260 --> 00:37:08,010 think here this is a lack of carbon and 1046 00:37:11,930 --> 00:37:09,270 so the more you put in the more 1047 00:37:13,400 --> 00:37:11,940 particles you get this is probably to do 1048 00:37:15,650 --> 00:37:13,410 with the fact that you start having 1049 00:37:16,940 --> 00:37:15,660 shielding from methane and so the 1050 00:37:18,260 --> 00:37:16,950 photons can't participate in the 1051 00:37:20,599 --> 00:37:18,270 chemistry can't drive the chemistry as 1052 00:37:22,849 --> 00:37:20,609 much so this does what we already knew 1053 00:37:26,180 --> 00:37:22,859 it would do that was good then we 1054 00:37:28,190 --> 00:37:26,190 started adding co2 and in all cases in 1055 00:37:29,810 --> 00:37:28,200 these experiments there is more co2 in 1056 00:37:31,640 --> 00:37:29,820 the gas phase than there is methane 1057 00:37:34,010 --> 00:37:31,650 except for the experiment that didn't 1058 00:37:35,570 --> 00:37:34,020 have any co2 and we turn this been 1059 00:37:36,890 --> 00:37:35,580 demonstrated before that when you put 1060 00:37:39,410 --> 00:37:36,900 co2 in the gas mixture 1061 00:37:41,270 --> 00:37:39,420 unlike Co you do decrease particle 1062 00:37:41,829 --> 00:37:41,280 formation you do decrease the production 1063 00:37:43,749 --> 00:37:41,839 rate 1064 00:37:46,299 --> 00:37:43,759 so those are those points so now we have 1065 00:37:48,309 --> 00:37:46,309 only methane and nitrogen then we have 1066 00:37:52,959 --> 00:37:48,319 methane nitrogen co2 and now we're gonna 1067 00:37:54,999 --> 00:37:52,969 add otwo to the gas mixture and we start 1068 00:37:58,199 --> 00:37:55,009 with a very small amount only about two 1069 00:38:01,449 --> 00:37:58,209 parts per million and went up 2.2% 1070 00:38:03,670 --> 00:38:01,459 interestingly putting a tiny amount of 1071 00:38:06,549 --> 00:38:03,680 oxygen in the gas mixture actually makes 1072 00:38:07,959 --> 00:38:06,559 the production rate go up I suspect 1073 00:38:09,969 --> 00:38:07,969 that's to do with this point that I 1074 00:38:11,650 --> 00:38:09,979 already brought up about oxygen 1075 00:38:13,179 --> 00:38:11,660 containing molecules being useful for 1076 00:38:15,880 --> 00:38:13,189 pulling molecular hydrogen out of the 1077 00:38:18,789 --> 00:38:15,890 gas phase and then as we put more 1078 00:38:20,109 --> 00:38:18,799 molecular oxygen into the gas we had a 1079 00:38:21,579 --> 00:38:20,119 decrease in production rate which is 1080 00:38:23,289 --> 00:38:21,589 probably not surprising because it was 1081 00:38:24,459 --> 00:38:23,299 what everybody thought all along but 1082 00:38:26,739 --> 00:38:24,469 nobody had ever actually done the 1083 00:38:28,390 --> 00:38:26,749 experiment to show that but just to give 1084 00:38:30,519 --> 00:38:28,400 you a sense of what the production rates 1085 00:38:31,599 --> 00:38:30,529 look like this is our standard tight in 1086 00:38:34,059 --> 00:38:31,609 the experiment and that in that 1087 00:38:36,519 --> 00:38:34,069 particular setup so actually a bunch of 1088 00:38:38,679 --> 00:38:36,529 these experiments have have a higher 1089 00:38:40,630 --> 00:38:38,689 production rate than Titan which is 1090 00:38:42,699 --> 00:38:40,640 super super interesting because as I 1091 00:38:46,689 --> 00:38:42,709 mentioned there's more co2 in these 1092 00:38:48,189 --> 00:38:46,699 experiments and there is methane this is 1093 00:38:50,650 --> 00:38:48,199 what the lab looked like one of the days 1094 00:38:53,019 --> 00:38:50,660 that I was doing the experiment you can 1095 00:38:56,140 --> 00:38:53,029 see down to the end of the lab so it's 1096 00:38:57,729 --> 00:38:56,150 not particularly hazy which is good 1097 00:39:01,029 --> 00:38:57,739 because I spent three years breathing 1098 00:39:03,549 --> 00:39:01,039 that air for about ten hours a day and 1099 00:39:04,959 --> 00:39:03,559 then just to give you a sense that these 1100 00:39:07,329 --> 00:39:04,969 are these are real we are actually 1101 00:39:09,069 --> 00:39:07,339 making particles this is what the gases 1102 00:39:10,509 --> 00:39:09,079 look like when they ran all the way 1103 00:39:12,640 --> 00:39:10,519 through the experiment without the 1104 00:39:14,289 --> 00:39:12,650 energy source on and so in every single 1105 00:39:16,689 --> 00:39:14,299 one of these experiments including the 1106 00:39:18,880 --> 00:39:16,699 ones that had point 2% molecular oxygen 1107 00:39:19,390 --> 00:39:18,890 we were still making particles in the 1108 00:39:21,339 --> 00:39:19,400 atmosphere 1109 00:39:23,319 --> 00:39:21,349 I hope the take-home message from that 1110 00:39:25,359 --> 00:39:23,329 is particles like atmospheres really 1111 00:39:27,429 --> 00:39:25,369 want to make particles like you give 1112 00:39:29,019 --> 00:39:27,439 gases photons and they want to they want 1113 00:39:31,269 --> 00:39:29,029 to convert some of those gases into 1114 00:39:33,789 --> 00:39:31,279 solid it's just a question of how much 1115 00:39:35,049 --> 00:39:33,799 and by which pathways it turns out a lot 1116 00:39:38,229 --> 00:39:35,059 of really interesting things happen when 1117 00:39:40,150 --> 00:39:38,239 we look at the particles too so when we 1118 00:39:41,739 --> 00:39:40,160 looked at the composition of the 1119 00:39:44,319 --> 00:39:41,749 particles we see that the addition of 1120 00:39:46,599 --> 00:39:44,329 molecular oxygen increases nitrogen 1121 00:39:48,549 --> 00:39:46,609 fixation and so all of a sudden the 1122 00:39:51,429 --> 00:39:48,559 nitrogen is participating more actively 1123 00:39:53,169 --> 00:39:51,439 in the solid phase and so we're actually 1124 00:39:54,930 --> 00:39:53,179 I see one person really appreciating 1125 00:39:57,240 --> 00:39:54,940 what I'm saying right now thank you 1126 00:39:59,400 --> 00:39:57,250 maybe the recipe r2 but if someone 1127 00:40:00,809 --> 00:39:59,410 really got what I was about to say and 1128 00:40:02,400 --> 00:40:00,819 so what we see in these particles that 1129 00:40:04,799 --> 00:40:02,410 are produced as much oxygen factual 1130 00:40:07,920 --> 00:40:04,809 information of organic nitrate in the 1131 00:40:09,150 --> 00:40:07,930 atmosphere from photochemistry and 1132 00:40:11,160 --> 00:40:09,160 actually during a period of Earth's 1133 00:40:13,020 --> 00:40:11,170 history when organic nitrate may have 1134 00:40:16,380 --> 00:40:13,030 been a useful thing to have raining from 1135 00:40:17,789 --> 00:40:16,390 the sky so that's cool and then one of 1136 00:40:20,370 --> 00:40:17,799 the other things that I really want to 1137 00:40:21,720 --> 00:40:20,380 emphasize about this work because I 1138 00:40:24,750 --> 00:40:21,730 think it's important for this discussion 1139 00:40:26,609 --> 00:40:24,760 discussion of optical properties for 1140 00:40:29,010 --> 00:40:26,619 those of you think about nnk I put this 1141 00:40:30,690 --> 00:40:29,020 here for you and this here for you for 1142 00:40:32,480 --> 00:40:30,700 those who don't think about nnk I'm 1143 00:40:35,910 --> 00:40:32,490 going to tell you what you are seeing 1144 00:40:37,859 --> 00:40:35,920 when we put oxygen into these 1145 00:40:40,020 --> 00:40:37,869 experiments even relatively small 1146 00:40:42,569 --> 00:40:40,030 amounts of oxygen we converted these 1147 00:40:44,099 --> 00:40:42,579 Brown gunky particles that everyone is 1148 00:40:45,960 --> 00:40:44,109 familiar with that I already showed you 1149 00:40:49,230 --> 00:40:45,970 a bunch of pictures of into particles 1150 00:40:51,569 --> 00:40:49,240 that do not absorb photons period end of 1151 00:40:53,970 --> 00:40:51,579 discussion like they are highly 1152 00:40:55,380 --> 00:40:53,980 reflective effectively having teeny tiny 1153 00:40:58,170 --> 00:40:55,390 mirrors floating around in the 1154 00:41:00,029 --> 00:40:58,180 atmosphere just with the addition of a 1155 00:41:02,640 --> 00:41:00,039 little bit of molecular oxygen into the 1156 00:41:03,930 --> 00:41:02,650 gas phase this is super important for 1157 00:41:05,940 --> 00:41:03,940 this period of time in early Earth's 1158 00:41:08,190 --> 00:41:05,950 history but it's also just to 1159 00:41:10,440 --> 00:41:08,200 demonstrate that small changes in the 1160 00:41:12,180 --> 00:41:10,450 composition of the atmosphere can result 1161 00:41:14,130 --> 00:41:12,190 in huge changes in the optical 1162 00:41:15,779 --> 00:41:14,140 properties of the particles which is one 1163 00:41:17,220 --> 00:41:15,789 of the reasons why we need more optical 1164 00:41:19,170 --> 00:41:17,230 constants measurements so that you're 1165 00:41:21,420 --> 00:41:19,180 not all stuck with that one paper from 1166 00:41:22,980 --> 00:41:21,430 1984 which I suspect in this audience 1167 00:41:26,670 --> 00:41:22,990 may actually have been before quite a 1168 00:41:27,779 --> 00:41:26,680 few of you were born yeah no I know some 1169 00:41:31,289 --> 00:41:27,789 of you are laughing uncomfortably you 1170 00:41:32,700 --> 00:41:31,299 know it's true and so just to give you a 1171 00:41:35,039 --> 00:41:32,710 quick summary of what we learned for the 1172 00:41:36,480 --> 00:41:35,049 like Euler oxygen experiment we know 1173 00:41:39,269 --> 00:41:36,490 that with relatively small amounts of 1174 00:41:40,799 --> 00:41:39,279 methane we can produce aerosol in the 1175 00:41:43,260 --> 00:41:40,809 lab with up to 200 parts per million 1176 00:41:45,029 --> 00:41:43,270 oxygen present in the gas mixture in 1177 00:41:48,150 --> 00:41:45,039 those experiments not only is there more 1178 00:41:50,309 --> 00:41:48,160 co2 present in the gas mixture than 1179 00:41:52,049 --> 00:41:50,319 methane there is more Oh to present in 1180 00:41:54,960 --> 00:41:52,059 the gas mixture than methane and we're 1181 00:41:56,819 --> 00:41:54,970 still making particles as the oxygen 1182 00:41:58,620 --> 00:41:56,829 concentration increases the aerosol 1183 00:42:01,890 --> 00:41:58,630 becomes increasingly oxygen and nitrogen 1184 00:42:03,150 --> 00:42:01,900 rich and then the addition of oxygen 1185 00:42:05,099 --> 00:42:03,160 results in an increase in nitrogen 1186 00:42:08,059 --> 00:42:05,109 fixation which is cool so the chemistry 1187 00:42:09,229 --> 00:42:08,069 is really changing and 1188 00:42:10,910 --> 00:42:09,239 finally the addition of this small 1189 00:42:12,739 --> 00:42:10,920 amount of o2 results in particles that 1190 00:42:14,749 --> 00:42:12,749 don't absorb photons which is super 1191 00:42:16,130 --> 00:42:14,759 weird like we didn't believe it so we 1192 00:42:19,609 --> 00:42:16,140 checked it with another technique just 1193 00:42:21,439 --> 00:42:19,619 to be sure and that said the same thing 1194 00:42:24,289 --> 00:42:21,449 so I want to go back to this picture 1195 00:42:27,349 --> 00:42:24,299 that we started with that we kind of 1196 00:42:29,870 --> 00:42:27,359 came out of this you know era of Titan 1197 00:42:32,449 --> 00:42:29,880 with this idea that organic haze is 1198 00:42:37,640 --> 00:42:32,459 produced from methane photochemistry it 1199 00:42:38,900 --> 00:42:37,650 mildly reduced atmospheres I hope after 1200 00:42:40,549 --> 00:42:38,910 telling you about all of those 1201 00:42:42,229 --> 00:42:40,559 experiments which I actually got through 1202 00:42:45,769 --> 00:42:42,239 miraculously probably because I talked 1203 00:42:46,999 --> 00:42:45,779 to you fast there are many many pathways 1204 00:42:49,309 --> 00:42:47,009 for the generation of photochemical 1205 00:42:51,739 --> 00:42:49,319 Hayes's some of those pathways don't 1206 00:42:55,699 --> 00:42:51,749 even require there to be methane in the 1207 00:42:57,979 --> 00:42:55,709 gas mixture to begin with some of those 1208 00:43:00,380 --> 00:42:57,989 pathways go against all conventional 1209 00:43:02,660 --> 00:43:00,390 wisdom that we have ever had about how 1210 00:43:06,349 --> 00:43:02,670 chemistry works in terms of converting 1211 00:43:07,400 --> 00:43:06,359 gases into particles like I said there 1212 00:43:10,370 --> 00:43:07,410 appeared to be a pathways that don't 1213 00:43:12,769 --> 00:43:10,380 require methane oxygen very molecules 1214 00:43:15,799 --> 00:43:12,779 each play a really unique role in haze 1215 00:43:19,069 --> 00:43:15,809 formation I think this is happening for 1216 00:43:20,569 --> 00:43:19,079 a few different reasons I think one of 1217 00:43:22,699 --> 00:43:20,579 the main reasons that it's happening is 1218 00:43:24,829 --> 00:43:22,709 because if you look at the absorption 1219 00:43:27,380 --> 00:43:24,839 spectra of oxygen containing molecules 1220 00:43:29,959 --> 00:43:27,390 we've seen a couple of them over the 1221 00:43:32,779 --> 00:43:29,969 past day and a half they all interact 1222 00:43:34,279 --> 00:43:32,789 with light very very differently and so 1223 00:43:36,229 --> 00:43:34,289 the fact that they're absorbing photons 1224 00:43:38,959 --> 00:43:36,239 of different wavelengths really affects 1225 00:43:40,459 --> 00:43:38,969 how the photochemistry proceed in part 1226 00:43:41,839 --> 00:43:40,469 because we need both the short 1227 00:43:44,180 --> 00:43:41,849 wavelength photons to start the 1228 00:43:46,969 --> 00:43:44,190 chemistry to break things like molecular 1229 00:43:48,910 --> 00:43:46,979 nitrogen which has a triple bond but we 1230 00:43:51,890 --> 00:43:48,920 also need a longer wavelength photons to 1231 00:43:53,660 --> 00:43:51,900 keep the chemistry going so to take 1232 00:43:56,239 --> 00:43:53,670 things like ethane and acetylene and 1233 00:43:58,009 --> 00:43:56,249 benzene and break them up and continue 1234 00:44:00,439 --> 00:43:58,019 the chemistry so we need we need all of 1235 00:44:01,910 --> 00:44:00,449 the photons we need all the UV photons 1236 00:44:03,229 --> 00:44:01,920 anyway I don't care about the visible 1237 00:44:06,499 --> 00:44:03,239 ones they can go do whatever they want 1238 00:44:08,959 --> 00:44:06,509 to do I want all the UV photon and so 1239 00:44:10,699 --> 00:44:08,969 the way in which that the gases interact 1240 00:44:12,769 --> 00:44:10,709 with the UV photons really matters and 1241 00:44:15,739 --> 00:44:12,779 this is also a really important lesson 1242 00:44:16,729 --> 00:44:15,749 for thinking about exoplanets because we 1243 00:44:19,549 --> 00:44:16,739 have all these different kinds of 1244 00:44:20,989 --> 00:44:19,559 stuffers which is really annoying I'm 1245 00:44:21,920 --> 00:44:20,999 super excited about it because they're 1246 00:44:23,599 --> 00:44:21,930 each their own little 1247 00:44:25,000 --> 00:44:23,609 experiment about what happens when you 1248 00:44:27,140 --> 00:44:25,010 were radiate with different way looks 1249 00:44:29,059 --> 00:44:27,150 but that's very hard to replicate in the 1250 00:44:30,890 --> 00:44:29,069 lab and it says something that we have 1251 00:44:32,660 --> 00:44:30,900 to think about I think the other reason 1252 00:44:34,309 --> 00:44:32,670 that the Austin Berry molecules each do 1253 00:44:35,930 --> 00:44:34,319 something really different is because 1254 00:44:39,620 --> 00:44:35,940 once they are fragmented once they do 1255 00:44:41,390 --> 00:44:39,630 interact with photon the pieces that 1256 00:44:42,799 --> 00:44:41,400 produced are very different chemically 1257 00:44:45,260 --> 00:44:42,809 and are going to participate in 1258 00:44:46,220 --> 00:44:45,270 chemistry in very different ways one of 1259 00:44:47,750 --> 00:44:46,230 the reasons that I really want to 1260 00:44:50,059 --> 00:44:47,760 emphasize the oxygen bearing molecules 1261 00:44:51,740 --> 00:44:50,069 also is that we have a habit and this 1262 00:44:53,359 --> 00:44:51,750 happens in the solar system to of 1263 00:44:56,240 --> 00:44:53,369 thinking about Hayes formation in terms 1264 00:44:57,920 --> 00:44:56,250 of the sitio ratio in the gases and 1265 00:45:00,740 --> 00:44:57,930 there's lots of different ways to get 1266 00:45:02,329 --> 00:45:00,750 specific field ratios depending on which 1267 00:45:05,620 --> 00:45:02,339 oxygen containing molecules are looking 1268 00:45:07,910 --> 00:45:05,630 at and so that probably isn't the best 1269 00:45:09,740 --> 00:45:07,920 metric for thinking about whether or not 1270 00:45:12,680 --> 00:45:09,750 an atmosphere would be favorable for 1271 00:45:14,420 --> 00:45:12,690 hayes formation it turned out that 1272 00:45:16,700 --> 00:45:14,430 oxidized atmospheres may also be 1273 00:45:19,670 --> 00:45:16,710 favorable for his formation depending on 1274 00:45:21,349 --> 00:45:19,680 other things about them what is the 1275 00:45:24,740 --> 00:45:21,359 temperature what does their star look 1276 00:45:26,089 --> 00:45:24,750 like what other gases are present like I 1277 00:45:28,880 --> 00:45:26,099 said with this hydrogen sulfide 1278 00:45:31,039 --> 00:45:28,890 experiment now we're seeing that you can 1279 00:45:32,660 --> 00:45:31,049 have a co2 dominated atmosphere that 1280 00:45:34,700 --> 00:45:32,670 still actually is pretty efficient at 1281 00:45:38,000 --> 00:45:34,710 producing particles because we have this 1282 00:45:41,020 --> 00:45:38,010 new atom in the gas mixture that's 1283 00:45:44,210 --> 00:45:41,030 really good at building things and 1284 00:45:46,490 --> 00:45:44,220 finally one other thing to point out and 1285 00:45:48,200 --> 00:45:46,500 we had a discussion about the the ways 1286 00:45:50,720 --> 00:45:48,210 in which Earth's atmosphere has been up 1287 00:45:52,220 --> 00:45:50,730 to shenanigans over its history earlier 1288 00:45:55,490 --> 00:45:52,230 today but as the planet atmosphere 1289 00:45:56,690 --> 00:45:55,500 evolves its haze will - and one of the 1290 00:45:57,890 --> 00:45:56,700 things that we know about planetary 1291 00:46:00,650 --> 00:45:57,900 atmospheres is that they're constantly 1292 00:46:02,390 --> 00:46:00,660 evolving over time because they are 1293 00:46:04,940 --> 00:46:02,400 undergoing atmospheric escape because 1294 00:46:06,319 --> 00:46:04,950 there may be changes from volcanism or 1295 00:46:08,299 --> 00:46:06,329 from impacts or all these other things 1296 00:46:10,039 --> 00:46:08,309 so the composition is always changing 1297 00:46:12,200 --> 00:46:10,049 and that means that the possibility that 1298 00:46:13,970 --> 00:46:12,210 there's going to be a haze layer present 1299 00:46:15,859 --> 00:46:13,980 or not will also change over time and 1300 00:46:18,470 --> 00:46:15,869 that's something really complicated that 1301 00:46:22,039 --> 00:46:18,480 we have to think about so the moral of 1302 00:46:24,309 --> 00:46:22,049 the story for this slide is basically 1303 00:46:26,690 --> 00:46:24,319 that there's still a lot of work to do 1304 00:46:28,880 --> 00:46:26,700 and in part the reason that there's 1305 00:46:30,440 --> 00:46:28,890 still so much work to do is that we 1306 00:46:34,460 --> 00:46:30,450 can't calculate any of these things from 1307 00:46:35,170 --> 00:46:34,470 first principles and so we really need a 1308 00:46:36,880 --> 00:46:35,180 robust 1309 00:46:39,609 --> 00:46:36,890 experimental and theoretical framework 1310 00:46:42,190 --> 00:46:39,619 to try to understand how gases convert 1311 00:46:43,630 --> 00:46:42,200 into particles and right now the only 1312 00:46:45,760 --> 00:46:43,640 place that we really have a good 1313 00:46:47,290 --> 00:46:45,770 framework for that is Earth and the 1314 00:46:49,710 --> 00:46:47,300 reason for that is because the earth 1315 00:46:52,450 --> 00:46:49,720 community has spent so much time 1316 00:46:53,790 --> 00:46:52,460 meticulously figuring out how every gas 1317 00:46:56,049 --> 00:46:53,800 that matters in Earth's atmosphere 1318 00:46:58,420 --> 00:46:56,059 interacts with every particle that 1319 00:46:59,710 --> 00:46:58,430 matters in Earth's atmosphere I've asked 1320 00:47:01,000 --> 00:46:59,720 them if they could do it for the rest of 1321 00:47:02,670 --> 00:47:01,010 the universe and they kind of rolled 1322 00:47:05,799 --> 00:47:02,680 their eyes at me 1323 00:47:07,270 --> 00:47:05,809 but this is kind of I think you know our 1324 00:47:09,549 --> 00:47:07,280 first baby steps forward and she's 1325 00:47:11,890 --> 00:47:09,559 trying to understand bigger picture how 1326 00:47:15,370 --> 00:47:11,900 haze formation precedes so that we are 1327 00:47:17,500 --> 00:47:15,380 able to actually bridge this gap that we 1328 00:47:19,900 --> 00:47:17,510 have between the small molecules that 1329 00:47:21,190 --> 00:47:19,910 we're pretty good at modeling and the 1330 00:47:22,990 --> 00:47:21,200 particles that are large enough that we 1331 00:47:24,880 --> 00:47:23,000 can start thinking about them in terms 1332 00:47:27,130 --> 00:47:24,890 of micro physics rather than chemistry 1333 00:47:29,859 --> 00:47:27,140 but there's a huge gap between those 1334 00:47:31,540 --> 00:47:29,869 those two things we haven't solved it in 1335 00:47:34,270 --> 00:47:31,550 the solar system we don't know how that 1336 00:47:36,579 --> 00:47:34,280 works on Titan I'm hoping that something 1337 00:47:37,780 --> 00:47:36,589 that is happening soon see I was going 1338 00:47:41,079 --> 00:47:37,790 to sneak it in you all knew I was gonna 1339 00:47:43,420 --> 00:47:41,089 stick it in will help us to bridge that 1340 00:47:46,750 --> 00:47:43,430 gap by actually measuring the real 1341 00:47:48,220 --> 00:47:46,760 particles in a real place but until then 1342 00:47:50,980 --> 00:47:48,230 we don't really have that framework 1343 00:47:52,299 --> 00:47:50,990 anywhere not just for exoplanets but 1344 00:47:53,500 --> 00:47:52,309 also in the solar system and so 1345 00:47:55,720 --> 00:47:53,510 something that we have to keep in mind 1346 00:48:00,700 --> 00:47:55,730 when we're thinking about haze formation 1347 00:48:06,099 --> 00:48:00,710 and I think I'm almost out of time well 1348 00:48:07,660 --> 00:48:06,109 I could tap dance before you know I am 1349 00:48:11,640 --> 00:48:07,670 good I would love to take questions 1350 00:48:11,650 --> 00:48:15,220 [Music] 1351 00:48:15,230 --> 00:48:21,700 so we have a lot of questions so yeah 1352 00:48:26,120 --> 00:48:24,530 naked main university Rickster sorry 1353 00:48:28,460 --> 00:48:26,130 this is a really basic question about 1354 00:48:30,800 --> 00:48:28,470 the experimental setup I think I was 1355 00:48:32,420 --> 00:48:30,810 misled a little bit at one point so when 1356 00:48:34,970 --> 00:48:32,430 you were showing the images of particles 1357 00:48:37,520 --> 00:48:34,980 on the surface when you're forming these 1358 00:48:39,530 --> 00:48:37,530 things do they form on the surfaces 1359 00:48:41,270 --> 00:48:39,540 inside the experiment is that acting as 1360 00:48:42,980 --> 00:48:41,280 a catalyst accelerate it was it straight 1361 00:48:45,200 --> 00:48:42,990 out of the ground so one of the things 1362 00:48:47,030 --> 00:48:45,210 that determines the pressure in our 1363 00:48:49,040 --> 00:48:47,040 experiment which I didn't say which is a 1364 00:48:51,620 --> 00:48:49,050 millibar so there you go now you know 1365 00:48:53,660 --> 00:48:51,630 that - it's trying to make sure that all 1366 00:48:56,150 --> 00:48:53,670 of the chemistry all the molecules as 1367 00:48:58,010 --> 00:48:56,160 they're participating chemistry are 1368 00:49:00,140 --> 00:48:58,020 colliding more often with themselves in 1369 00:49:01,940 --> 00:49:00,150 the wall but also make sure that the 1370 00:49:03,440 --> 00:49:01,950 particles are actually forming not on 1371 00:49:05,420 --> 00:49:03,450 the wall but in the experiments 1372 00:49:07,130 --> 00:49:05,430 themselves so something that people have 1373 00:49:09,050 --> 00:49:07,140 spent a lot of time and effort trying to 1374 00:49:11,510 --> 00:49:09,060 make sure if we don't actually have like 1375 00:49:13,490 --> 00:49:11,520 giant stainless steel surfaces I'm in 1376 00:49:15,620 --> 00:49:13,500 real atmosphere but that is something 1377 00:49:16,940 --> 00:49:15,630 that we have to think about quite a bit 1378 00:49:19,089 --> 00:49:16,950 and do spend a lot of time worrying 1379 00:49:21,410 --> 00:49:19,099 about but the particles are made 1380 00:49:22,880 --> 00:49:21,420 effectively in suspension and that's 1381 00:49:24,500 --> 00:49:22,890 part of actually what sets their size so 1382 00:49:26,450 --> 00:49:24,510 I meant to say this earlier it came up 1383 00:49:27,710 --> 00:49:26,460 this morning I think this morning I'm 1384 00:49:30,710 --> 00:49:27,720 trying to lose track of time I'm a 1385 00:49:32,420 --> 00:49:30,720 little jet-lagged but one of the one of 1386 00:49:34,700 --> 00:49:32,430 the things that is challenging is that 1387 00:49:36,500 --> 00:49:34,710 although we're trying very very hard to 1388 00:49:38,450 --> 00:49:36,510 mimic the chemical processes correctly 1389 00:49:40,819 --> 00:49:38,460 we're not bothering with the physical 1390 00:49:42,380 --> 00:49:40,829 processes they're all and so when we 1391 00:49:43,849 --> 00:49:42,390 look at the size distributions one of 1392 00:49:46,160 --> 00:49:43,859 this that we're really concerned about 1393 00:49:48,109 --> 00:49:46,170 the size distributions is to compare 1394 00:49:49,220 --> 00:49:48,119 them to other experiments to say okay 1395 00:49:51,410 --> 00:49:49,230 these particles are bigger these 1396 00:49:52,760 --> 00:49:51,420 particles are smaller in a real 1397 00:49:55,670 --> 00:49:52,770 atmosphere the particles have the 1398 00:49:57,589 --> 00:49:55,680 opportunity to stick they can form 1399 00:49:58,910 --> 00:49:57,599 larger spherical particles or they may 1400 00:50:00,440 --> 00:49:58,920 stick and form these beautiful fractal 1401 00:50:02,240 --> 00:50:00,450 aggregates that we think are present in 1402 00:50:03,620 --> 00:50:02,250 Titan's atmosphere none of that happens 1403 00:50:05,180 --> 00:50:03,630 in these experiments because we're not 1404 00:50:08,569 --> 00:50:05,190 seeing them a thousand kilometers to 1405 00:50:10,339 --> 00:50:08,579 fall um I keep asking Hopkins if they 1406 00:50:13,040 --> 00:50:10,349 could build me a thousand kilometer tall 1407 00:50:14,809 --> 00:50:13,050 lab and they can't even build me one 1408 00:50:21,010 --> 00:50:14,819 that functions correctly that has you 1409 00:50:23,089 --> 00:50:21,020 know eight-foot ceilings so but what I 1410 00:50:25,460 --> 00:50:23,099 couldn't hear what I couldn't hear was 1411 00:50:27,370 --> 00:50:25,470 it oh yeah no it's fine I talked about 1412 00:50:29,140 --> 00:50:27,380 on Twitter all the time my 1413 00:50:30,730 --> 00:50:29,150 alarms went off two minutes before we 1414 00:50:37,630 --> 00:50:30,740 started this talk so we could go down 1415 00:50:40,690 --> 00:50:37,640 that road I Sarah I wanted to ask you a 1416 00:50:42,519 --> 00:50:40,700 bit of details and how do you choose the 1417 00:50:44,859 --> 00:50:42,529 actuator the gases you put in because 1418 00:50:47,319 --> 00:50:44,869 you're bad you're seven matee sitar but 1419 00:50:49,240 --> 00:50:47,329 you're showing that things like h2s even 1420 00:50:50,859 --> 00:50:49,250 as small quantities kind of strong 1421 00:50:53,079 --> 00:50:50,869 effect but you don't put them under 1422 00:50:55,749 --> 00:50:53,089 hundred times Felicity or as very steady 1423 00:50:57,249 --> 00:50:55,759 yeah it should still be some absolutely 1424 00:51:03,870 --> 00:50:57,259 okay that's like that's a great point 1425 00:51:07,089 --> 00:51:03,880 and we chose a cut-off for sanity so the 1426 00:51:09,220 --> 00:51:07,099 thousand times experiments have like six 1427 00:51:10,690 --> 00:51:09,230 or seven gases in them which are the 1428 00:51:13,029 --> 00:51:10,700 most complex experiments of this type 1429 00:51:15,240 --> 00:51:13,039 that anyone had ever done we decided 1430 00:51:19,539 --> 00:51:15,250 that was the most we were going to use 1431 00:51:21,700 --> 00:51:19,549 that put us at a 1% mixing ratio cup so 1432 00:51:24,579 --> 00:51:21,710 we used one percent across the board for 1433 00:51:27,849 --> 00:51:24,589 all of the experiment so it's certainly 1434 00:51:30,759 --> 00:51:27,859 true that in some of those cases there 1435 00:51:33,249 --> 00:51:30,769 were gases at like 0.9% that we did not 1436 00:51:35,109 --> 00:51:33,259 include so if you look at the hundred 1437 00:51:37,720 --> 00:51:35,119 times metallicity case only the lowest 1438 00:51:39,279 --> 00:51:37,730 temperature has ammonia in it it's not 1439 00:51:41,650 --> 00:51:39,289 that there isn't ammonia and those other 1440 00:51:44,799 --> 00:51:41,660 gases it's just that like it was it's 1441 00:51:46,420 --> 00:51:44,809 below the 1% level so what we're gonna 1442 00:51:49,690 --> 00:51:46,430 do is figure out how each of these gases 1443 00:51:51,970 --> 00:51:49,700 matter now we know that sulfur matters 1444 00:51:54,460 --> 00:51:51,980 and so if we go back through and look at 1445 00:51:56,799 --> 00:51:54,470 the ten thousand times cases I think 1446 00:51:58,690 --> 00:51:56,809 hydrogen sulfide is it's still in those 1447 00:52:00,670 --> 00:51:58,700 gas mixtures it's just at a lower level 1448 00:52:02,769 --> 00:52:00,680 the thing that I will tell you is the 1449 00:52:04,779 --> 00:52:02,779 only direction in which this is going to 1450 00:52:06,549 --> 00:52:04,789 impact the production rate if we start 1451 00:52:08,589 --> 00:52:06,559 adding those trace gases is to make the 1452 00:52:10,509 --> 00:52:08,599 production rates higher nothing that is 1453 00:52:12,720 --> 00:52:10,519 lurking below that cutoff is going to 1454 00:52:16,509 --> 00:52:12,730 make any of these production rates lower 1455 00:52:18,789 --> 00:52:16,519 and so that was you know that was a 1456 00:52:19,990 --> 00:52:18,799 choice we made I think depending on what 1457 00:52:21,130 --> 00:52:20,000 we want to do next we might be able to 1458 00:52:23,680 --> 00:52:21,140 go back through and add some of these 1459 00:52:25,990 --> 00:52:23,690 trace gases in and see you know if that 1460 00:52:28,180 --> 00:52:26,000 would have a big impact on some of them 1461 00:52:31,420 --> 00:52:28,190 but it was you know entirely a choice 1462 00:52:36,910 --> 00:52:31,430 made for sanity unfortunately or 1463 00:52:42,050 --> 00:52:36,920 fortunately I'm not sure which I think 1464 00:52:46,200 --> 00:52:42,060 stood for the dragonfly plug Sarah Moore 1465 00:52:49,800 --> 00:52:46,210 thank you the conventional wisdom that 1466 00:52:52,020 --> 00:52:49,810 that I think I learned and maybe it's 1467 00:52:53,550 --> 00:52:52,030 one of those myths that you've you know 1468 00:52:56,460 --> 00:52:53,560 some of the others of which you've been 1469 00:52:58,800 --> 00:52:56,470 dispelling is that in tighten the 1470 00:53:01,530 --> 00:52:58,810 nitrogen nitrogen bond is largely broken 1471 00:53:04,260 --> 00:53:01,540 by the magnetospheric electrons and the 1472 00:53:05,280 --> 00:53:04,270 more abundant UV can only break up the 1473 00:53:08,010 --> 00:53:05,290 CH bonds 1474 00:53:10,350 --> 00:53:08,020 is there anything we've learned from the 1475 00:53:13,650 --> 00:53:10,360 new horizons encounter with Pluto the 1476 00:53:16,860 --> 00:53:13,660 challenges or augments that picture yeah 1477 00:53:19,800 --> 00:53:16,870 so the extreme UV photons can break up 1478 00:53:21,060 --> 00:53:19,810 molecular nitrogen in sum total and I 1479 00:53:22,410 --> 00:53:21,070 have to go back and look at the paper to 1480 00:53:25,770 --> 00:53:22,420 see what the breakdown is between 1481 00:53:27,210 --> 00:53:25,780 nitrogen methane but in sum total 90% of 1482 00:53:30,150 --> 00:53:27,220 the chemistry and Titan's atmosphere is 1483 00:53:32,970 --> 00:53:30,160 driven by UV photons and only 10% comes 1484 00:53:35,550 --> 00:53:32,980 from the input of energetic ions of 1485 00:53:39,480 --> 00:53:35,560 whatever flavor they are into the top of 1486 00:53:41,370 --> 00:53:39,490 the atmosphere with New Horizons there 1487 00:53:43,710 --> 00:53:41,380 there's still a lot of work to do in 1488 00:53:46,230 --> 00:53:43,720 terms of trying to understand exactly 1489 00:53:48,450 --> 00:53:46,240 what's happening in that atmosphere 1490 00:53:51,300 --> 00:53:48,460 there's an ongoing debate about whether 1491 00:53:52,770 --> 00:53:51,310 the haze particles are very simple and 1492 00:53:56,070 --> 00:53:52,780 then they're actually just condensate of 1493 00:53:58,530 --> 00:53:56,080 things like I don't know acetylene or 1494 00:54:01,760 --> 00:53:58,540 whether they are more complicated in the 1495 00:54:03,840 --> 00:54:01,770 way that we think of Titan's atmosphere 1496 00:54:06,780 --> 00:54:03,850 my personal feeling is that they're 1497 00:54:08,160 --> 00:54:06,790 actually very analogous to Titan in part 1498 00:54:10,380 --> 00:54:08,170 because the pressures that we're 1499 00:54:12,000 --> 00:54:10,390 thinking about for Pluto are actually 1500 00:54:13,320 --> 00:54:12,010 the exact same pressures where we see 1501 00:54:14,960 --> 00:54:13,330 this chemistry happening on Titan's 1502 00:54:18,360 --> 00:54:14,970 atmosphere because it happened so high 1503 00:54:19,680 --> 00:54:18,370 and so there's still a lot of work to be 1504 00:54:22,230 --> 00:54:19,690 done there but I think there's some some 1505 00:54:23,070 --> 00:54:22,240 beautiful comparative planetology that 1506 00:54:26,010 --> 00:54:23,080 it's going to be done with the New 1507 00:54:27,390 --> 00:54:26,020 Horizons data I'm we're starting to 1508 00:54:29,010 --> 00:54:27,400 think more about Triton a little bit too 1509 00:54:30,750 --> 00:54:29,020 I think those three atmospheres are 1510 00:54:32,460 --> 00:54:30,760 going to be really interesting test 1511 00:54:34,010 --> 00:54:32,470 cases going forwards in terms of at 1512 00:54:36,540 --> 00:54:34,020 least trying to see if we can sort out 1513 00:54:45,540 --> 00:54:36,550 nitrogen CO methane atmosphere haze 1514 00:54:48,300 --> 00:54:45,550 formation but it's complicated thank you 1515 00:54:50,760 --> 00:54:48,310 for this very beautiful talk um I still 1516 00:54:53,460 --> 00:54:50,770 remain confused about the particle sizes 1517 00:54:54,340 --> 00:54:53,470 you are quoting on these bubble plots um 1518 00:54:56,560 --> 00:54:54,350 the 1519 00:54:58,240 --> 00:54:56,570 at which stage our kite are you 1520 00:55:00,340 --> 00:54:58,250 measuring the particle sizes or which 1521 00:55:02,230 --> 00:55:00,350 particle sizes you gave you gave 1522 00:55:04,330 --> 00:55:02,240 definite numbers for particle size right 1523 00:55:07,360 --> 00:55:04,340 yeah so are these the particle sizes on 1524 00:55:10,150 --> 00:55:07,370 these bubbly surfaces or are these mean 1525 00:55:12,910 --> 00:55:10,160 particle sizes of a distribution there 1526 00:55:15,280 --> 00:55:12,920 so the the particle sizes that I showed 1527 00:55:17,470 --> 00:55:15,290 oh it depends on which experiment I was 1528 00:55:20,440 --> 00:55:17,480 talking about but the exoplanet 1529 00:55:22,450 --> 00:55:20,450 experiment those are disks that are in 1530 00:55:24,070 --> 00:55:22,460 the chamber so those are particles that 1531 00:55:26,200 --> 00:55:24,080 have sedimented out of the experiment 1532 00:55:27,490 --> 00:55:26,210 and deposited on the chamber on the on 1533 00:55:28,930 --> 00:55:27,500 these disks in the chamber and then we 1534 00:55:32,110 --> 00:55:28,940 use those just to do atomic force 1535 00:55:34,540 --> 00:55:32,120 microscopy so we measure the particle 1536 00:55:36,520 --> 00:55:34,550 size distribution I didn't I probably 1537 00:55:38,020 --> 00:55:36,530 skipped over one of them breaks but we 1538 00:55:39,190 --> 00:55:38,030 measure the particle size distribution 1539 00:55:42,220 --> 00:55:39,200 and then what we were quoting was the 1540 00:55:43,960 --> 00:55:42,230 mean particle size but we also look at 1541 00:55:45,130 --> 00:55:43,970 how the size distribution itself changes 1542 00:56:00,640 --> 00:55:45,140 because there's information there as 1543 00:56:03,010 --> 00:56:00,650 well two small questions so firstly so 1544 00:56:04,900 --> 00:56:03,020 does this case form only in the upper 1545 00:56:08,050 --> 00:56:04,910 levels of the of the Titan's atmosphere 1546 00:56:10,630 --> 00:56:08,060 is it too cold for the highest form like 1547 00:56:13,180 --> 00:56:10,640 close to the surface at the production 1548 00:56:15,310 --> 00:56:13,190 rates too small that's a really 1549 00:56:17,590 --> 00:56:15,320 interesting question that I don't think 1550 00:56:19,390 --> 00:56:17,600 we actually know the answer to UM we 1551 00:56:21,130 --> 00:56:19,400 know that the chemistry that leads to 1552 00:56:23,110 --> 00:56:21,140 particle formation starts at the top of 1553 00:56:26,980 --> 00:56:23,120 the atmosphere we can see the particles 1554 00:56:29,920 --> 00:56:26,990 grow as we look deeper in the atmosphere 1555 00:56:32,110 --> 00:56:29,930 they get larger by the time we get to 1556 00:56:35,770 --> 00:56:32,120 the top of the stratosphere how the 1557 00:56:37,630 --> 00:56:35,780 start milho stratosphere we see that the 1558 00:56:40,930 --> 00:56:37,640 the spectra of the particles don't 1559 00:56:43,420 --> 00:56:40,940 change and so we interpret that to mean 1560 00:56:44,380 --> 00:56:43,430 that whatever the dynamical processes 1561 00:56:46,660 --> 00:56:44,390 are they're happening in the atmosphere 1562 00:56:48,400 --> 00:56:46,670 they're overwhelming any possible 1563 00:56:50,200 --> 00:56:48,410 chemical processes that are spending at 1564 00:56:52,540 --> 00:56:50,210 that point and so there's no ket there's 1565 00:56:55,570 --> 00:56:52,550 chemical difference between about 300 1566 00:56:57,250 --> 00:56:55,580 kilometers above the surface and and the 1567 00:56:59,200 --> 00:56:57,260 data that we get right below the the 1568 00:57:01,090 --> 00:56:59,210 surface but we do think there's physical 1569 00:57:02,470 --> 00:57:01,100 things happening there three to the 1570 00:57:03,940 --> 00:57:02,480 atmosphere where condensation should be 1571 00:57:05,590 --> 00:57:03,950 occurring it's a little bit surprising 1572 00:57:07,270 --> 00:57:05,600 that we don't seem to see the spectra 1573 00:57:10,180 --> 00:57:07,280 change very much 1574 00:57:13,780 --> 00:57:10,190 but to say where the chemistry starts 1575 00:57:17,500 --> 00:57:13,790 and stops is is very challenging yeah 1576 00:57:20,470 --> 00:57:17,510 and what's the role of ozone in in the 1577 00:57:22,930 --> 00:57:20,480 haze production experiments to include 1578 00:57:26,080 --> 00:57:22,940 that does it form yeah yeah 1579 00:57:29,080 --> 00:57:26,090 so in the early Earth experiments we 1580 00:57:30,310 --> 00:57:29,090 definitely were making ozone I can tell 1581 00:57:31,960 --> 00:57:30,320 you that because I end up having to run 1582 00:57:35,470 --> 00:57:31,970 those experiments for time because I was 1583 00:57:38,560 --> 00:57:35,480 on is not good and it was causing us all 1584 00:57:41,920 --> 00:57:38,570 kinds of challenges oh then we'll 1585 00:57:44,050 --> 00:57:41,930 certainly start to reverse the process a 1586 00:57:46,240 --> 00:57:44,060 little bit by scavenging organics and 1587 00:57:48,850 --> 00:57:46,250 converting them back into something 1588 00:57:50,140 --> 00:57:48,860 smaller so I think at some point what 1589 00:57:52,090 --> 00:57:50,150 starts to happen when we put more and 1590 00:57:54,040 --> 00:57:52,100 more o to into these experiments is the 1591 00:57:55,900 --> 00:57:54,050 combination of two things one the 1592 00:57:57,520 --> 00:57:55,910 oxygens eating a bunch of the photons 1593 00:58:00,070 --> 00:57:57,530 that we want to use for particle 1594 00:58:01,600 --> 00:58:00,080 formation and to in doing that it starts 1595 00:58:04,930 --> 00:58:01,610 creating a bunch of ozone which also 1596 00:58:06,940 --> 00:58:04,940 tamp down the production rates it's hard 1597 00:58:08,740 --> 00:58:06,950 because um you can't really measure 1598 00:58:10,270 --> 00:58:08,750 ozone because it's so reactive and you 1599 00:58:11,860 --> 00:58:10,280 would need to do it spectroscopically in 1600 00:58:13,960 --> 00:58:11,870 that particular setup we didn't have a 1601 00:58:15,670 --> 00:58:13,970 way to measure ozone and so I don't 1602 00:58:17,290 --> 00:58:15,680 actually have any measurements of the 1603 00:58:24,190 --> 00:58:17,300 gas composition from those experiments 1604 00:58:26,140 --> 00:58:24,200 yeah : Gold let you Vic thank you Sarah 1605 00:58:30,940 --> 00:58:26,150 for totally rad talk which changed how I 1606 00:58:33,210 --> 00:58:30,950 think about hazers a couple of questions 1607 00:58:36,130 --> 00:58:33,220 are singing right to mine the first is 1608 00:58:39,430 --> 00:58:36,140 for your neo Archaean experiment you 1609 00:58:43,240 --> 00:58:39,440 used a quite low co2 use 400 ppm so what 1610 00:58:46,390 --> 00:58:43,250 would happen if you use say 10,000 ppm 1611 00:58:48,660 --> 00:58:46,400 of co2 um I think that it would probably 1612 00:58:50,650 --> 00:58:48,670 follow the trends that we've seen before 1613 00:58:53,350 --> 00:58:50,660 which is that it would decrease the 1614 00:58:55,180 --> 00:58:53,360 particle production but I don't actually 1615 00:58:57,370 --> 00:58:55,190 know that for sure and the other thing 1616 00:58:58,630 --> 00:58:57,380 that is now super important that I 1617 00:58:59,830 --> 00:58:58,640 should have mentioned that I talked 1618 00:59:01,480 --> 00:58:59,840 about the earth experiments there was a 1619 00:59:03,610 --> 00:59:01,490 very important molecule missing from 1620 00:59:05,170 --> 00:59:03,620 those experiments that nobody ever did 1621 00:59:06,820 --> 00:59:05,180 any of this chemistry with before until 1622 00:59:08,440 --> 00:59:06,830 we did the exoplanet experiments but 1623 00:59:12,100 --> 00:59:08,450 there is definitely water in that 1624 00:59:13,720 --> 00:59:12,110 atmosphere and we've seen in the 1625 00:59:15,250 --> 00:59:13,730 exoplanet experiments that the water 1626 00:59:17,080 --> 00:59:15,260 dominated experiments have very high 1627 00:59:19,120 --> 00:59:17,090 production rates so I would love to go 1628 00:59:21,130 --> 00:59:19,130 back and redo those early Earth 1629 00:59:23,410 --> 00:59:21,140 experiments and actually include water 1630 00:59:24,849 --> 00:59:23,420 in the gas phase to see what would 1631 00:59:26,950 --> 00:59:24,859 happen in terms of page production there 1632 00:59:29,140 --> 00:59:26,960 too so I think if the co2 is higher the 1633 00:59:30,250 --> 00:59:29,150 particle production would go down but I 1634 00:59:31,420 --> 00:59:30,260 don't know what would happen if we 1635 00:59:34,000 --> 00:59:31,430 actually put water into those 1636 00:59:36,220 --> 00:59:34,010 experiments the ratios by the way were 1637 00:59:39,460 --> 00:59:36,230 the output of a model that was looking 1638 00:59:41,980 --> 00:59:39,470 at what types of gases we might expect 1639 00:59:43,779 --> 00:59:41,990 to see outgassing from like mid-ocean 1640 00:59:45,370 --> 00:59:43,789 ridges and volcanoes and stuff like that 1641 00:59:48,670 --> 00:59:45,380 so that's why there were very oddly 1642 00:59:49,990 --> 00:59:48,680 specific ratios of gases and those 1643 00:59:52,660 --> 00:59:50,000 experiments because they were the output 1644 00:59:54,339 --> 00:59:52,670 of a model my follow-up question would 1645 00:59:57,279 --> 00:59:54,349 be could you describe what you think the 1646 00:59:59,819 --> 00:59:57,289 history of behave in Earth has but they 1647 01:00:04,720 --> 00:59:59,829 have been to all of us history 1648 01:00:06,549 --> 01:00:04,730 buy me a drink later I think I think a 1649 01:00:08,140 --> 01:00:06,559 big picture you know I think Earth 1650 01:00:11,259 --> 01:00:08,150 probably did have a haze layer for a 1651 01:00:13,750 --> 01:00:11,269 good chunk of its early history I think 1652 01:00:16,329 --> 01:00:13,760 that the period of time that you showed 1653 01:00:18,279 --> 01:00:16,339 today in which the atmosphere is going 1654 01:00:21,190 --> 01:00:18,289 through all kinds of shenanigans in the 1655 01:00:22,630 --> 01:00:21,200 gas phase there were probably all kinds 1656 01:00:24,819 --> 01:00:22,640 of shenanigans going on with the haze 1657 01:00:26,710 --> 01:00:24,829 layer - in particular if we start 1658 01:00:28,690 --> 01:00:26,720 changing things like optical properties 1659 01:00:29,829 --> 01:00:28,700 then you start changing the way that the 1660 01:00:31,599 --> 01:00:29,839 rate of balance is working in the 1661 01:00:33,849 --> 01:00:31,609 atmosphere I give you a lot of feedbacks 1662 01:00:36,730 --> 01:00:33,859 that way volcanoes erupting I think that 1663 01:00:39,130 --> 01:00:36,740 period of time was really unstable and 1664 01:00:40,660 --> 01:00:39,140 so I suspect what was happening is that 1665 01:00:42,069 --> 01:00:40,670 sometimes there was a thicker haze layer 1666 01:00:44,140 --> 01:00:42,079 and sometimes there was a thinner haze 1667 01:00:45,880 --> 01:00:44,150 layer but I'm guessing that it took 1668 01:00:48,220 --> 01:00:45,890 quite a bit of time before it actually 1669 01:00:50,890 --> 01:00:48,230 fully dissipated if there was a thick 1670 01:00:52,420 --> 01:00:50,900 haze layer at the beginning which is not 1671 01:00:53,829 --> 01:00:52,430 the picture that we tend to think of 1672 01:00:55,630 --> 01:00:53,839 people tend to think of it more as a 1673 01:00:57,130 --> 01:00:55,640 light switch that once there was any 1674 01:00:58,480 --> 01:00:57,140 oxygen in the atmosphere that was it the 1675 01:01:03,630 --> 01:00:58,490 haze was gone and I don't think that's 1676 01:01:09,700 --> 01:01:07,289 hi my name is r.j. and I'm from here 1677 01:01:12,700 --> 01:01:09,710 this question comes from a place of 1678 01:01:14,799 --> 01:01:12,710 total ignorance did you said that you 1679 01:01:17,019 --> 01:01:14,809 all of the experiments were conducted at 1680 01:01:18,849 --> 01:01:17,029 one millibar of pressure all the 1681 01:01:21,549 --> 01:01:18,859 exoplanet experiments for Tamila Varia 1682 01:01:24,789 --> 01:01:21,559 do you expect that burying that would 1683 01:01:28,120 --> 01:01:24,799 matter at all yes that's not an ignorant 1684 01:01:29,410 --> 01:01:28,130 question at all so I mentioned that the 1685 01:01:31,180 --> 01:01:29,420 chemistry starts very high in Titan's 1686 01:01:34,359 --> 01:01:31,190 atmosphere that's a very challenging 1687 01:01:36,400 --> 01:01:34,369 region to access experimental ii 1688 01:01:38,979 --> 01:01:36,410 we try to have our chamber be many times 1689 01:01:40,209 --> 01:01:38,989 the mean free path of the gases again so 1690 01:01:42,429 --> 01:01:40,219 they're colliding more frequently with 1691 01:01:43,870 --> 01:01:42,439 each other than the wall to do that for 1692 01:01:46,509 --> 01:01:43,880 Titan atmosphere we would need a many 1693 01:01:47,739 --> 01:01:46,519 many kilometer box people don't like it 1694 01:01:49,479 --> 01:01:47,749 when I start talking about filling a 1695 01:01:51,969 --> 01:01:49,489 mini kilometer box with methane and then 1696 01:01:53,469 --> 01:01:51,979 I mean hating it on earth maybe someday 1697 01:01:56,739 --> 01:01:53,479 I'll get a moon base and then I do 1698 01:01:58,839 --> 01:01:56,749 sermons there so the pressure has chosen 1699 01:02:00,459 --> 01:01:58,849 in part because we know that that is a 1700 01:02:01,660 --> 01:02:00,469 region of atmospheres where a lot of 1701 01:02:03,489 --> 01:02:01,670 really interesting chemistry is 1702 01:02:05,679 --> 01:02:03,499 happening but it's also chosen in part 1703 01:02:07,749 --> 01:02:05,689 for reasons that are to do with being 1704 01:02:08,920 --> 01:02:07,759 practical in a lab and that's one of the 1705 01:02:10,569 --> 01:02:08,930 things that's frustrating about lab 1706 01:02:11,799 --> 01:02:10,579 experiments and so it's really 1707 01:02:14,019 --> 01:02:11,809 appreciated the point that was made this 1708 01:02:16,509 --> 01:02:14,029 morning about how we really have to work 1709 01:02:19,150 --> 01:02:16,519 together with experiments and models and 1710 01:02:21,099 --> 01:02:19,160 observations to actually figure out 1711 01:02:23,019 --> 01:02:21,109 what's going on because individually all