1 00:00:12,830 --> 00:00:10,730 well good afternoon my name is Dwayne 2 00:00:15,829 --> 00:00:12,840 brown with the office of communications 3 00:00:18,950 --> 00:00:15,839 here at NASA headquarters today you will 4 00:00:22,400 --> 00:00:18,960 hear first-hand new discoveries and a 5 00:00:25,340 --> 00:00:22,410 few surprises of planet Mercury revealed 6 00:00:27,950 --> 00:00:25,350 by NASA's messenger spacecraft and on 7 00:00:31,640 --> 00:00:27,960 March 18th of this year it became the 8 00:00:34,160 --> 00:00:31,650 first spacecraft ever to achieve orbit 9 00:00:36,650 --> 00:00:34,170 around this mysterious celestial body 10 00:00:40,670 --> 00:00:36,660 will have brief presentations from our 11 00:00:46,490 --> 00:00:40,680 participants a little surprise before we 12 00:00:49,130 --> 00:00:46,500 open up the Q&A and then we will go to 13 00:00:54,650 --> 00:00:49,140 the website where you can look at the 14 00:00:57,770 --> 00:00:54,660 various images and findings at wwc gov / 15 00:01:03,889 --> 00:00:57,780 messenger let me introduce you to 16 00:01:07,250 --> 00:01:03,899 today's participants first up Brett w de 17 00:01:09,520 --> 00:01:07,260 Neffe scientists Johns Hopkins 18 00:01:12,050 --> 00:01:09,530 University Applied Physics Laboratory 19 00:01:17,420 --> 00:01:12,060 otherwise known as a PL and lower 20 00:01:19,210 --> 00:01:17,430 Maryland Larry are knit ler scientists 21 00:01:23,740 --> 00:01:19,220 Department of terrestrial magnetism 22 00:01:30,740 --> 00:01:27,350 Chauncey Solomon messenger principal 23 00:01:36,010 --> 00:01:30,750 investigator from the Carnegie 24 00:01:39,260 --> 00:01:36,020 Institution also and Ralph L mcnutt jr. 25 00:01:42,410 --> 00:01:39,270 messenger project scientists also from 26 00:01:43,940 --> 00:01:42,420 APL before we start with the official 27 00:01:45,889 --> 00:01:43,950 presentations it's my honor and 28 00:01:48,770 --> 00:01:45,899 privilege to turn it over to Shawn for 29 00:01:51,260 --> 00:01:48,780 some opening remarks so on thank you 30 00:01:53,870 --> 00:01:51,270 doing we're delighted to be here today 31 00:01:56,060 --> 00:01:53,880 to share some of the findings from the 32 00:01:59,480 --> 00:01:56,070 first twenty five percent of our 33 00:02:00,620 --> 00:01:59,490 year-long mission messenger in orbit 34 00:02:02,959 --> 00:02:00,630 around one of our nearest planetary 35 00:02:05,240 --> 00:02:02,969 neighbors yet a planet that has never 36 00:02:07,880 --> 00:02:05,250 had an orbiting spacecraft before 37 00:02:09,639 --> 00:02:07,890 messenger I wanted to begin by telling 38 00:02:12,350 --> 00:02:09,649 you that we passed some substantial 39 00:02:13,040 --> 00:02:12,360 milestones just earlier this week in our 40 00:02:16,520 --> 00:02:13,050 mission 41 00:02:20,050 --> 00:02:16,530 on Sunday we had the first perihelion 42 00:02:24,040 --> 00:02:20,060 passage closest approach to the Sun 43 00:02:27,790 --> 00:02:24,050 since we've been in orbit on Monday we 44 00:02:30,410 --> 00:02:27,800 logged in one mercury year in orbit on 45 00:02:33,470 --> 00:02:30,420 Tuesday we came out of a solar 46 00:02:35,600 --> 00:02:33,480 conjunction when the Sun was in between 47 00:02:37,610 --> 00:02:35,610 Earth and the spacecraft allowing us to 48 00:02:40,070 --> 00:02:37,620 communicate again after being blocked 49 00:02:43,730 --> 00:02:40,080 and just yesterday we had the first 50 00:02:46,730 --> 00:02:43,740 orbit correction maneuver in orbit that 51 00:02:49,190 --> 00:02:46,740 lowered our closest approach to the 52 00:02:53,360 --> 00:02:49,200 planet back down to 200 kilometers or 53 00:02:56,540 --> 00:02:53,370 120 miles on most days since we've been 54 00:03:00,790 --> 00:02:56,550 in orbit we have received new data about 55 00:03:04,910 --> 00:03:00,800 this planetary neighbor of ours almost a 56 00:03:09,380 --> 00:03:04,920 non-stop new images new data from all of 57 00:03:12,920 --> 00:03:09,390 our seven instruments we had many ideas 58 00:03:17,060 --> 00:03:12,930 about mercury that were incomplete ill 59 00:03:19,130 --> 00:03:17,070 form that came out of the few flybys the 60 00:03:21,500 --> 00:03:19,140 three flybys by messenger and the three 61 00:03:23,740 --> 00:03:21,510 flybys in the 1970s by the first 62 00:03:27,470 --> 00:03:23,750 spacecraft to visit mercury mariner 10 63 00:03:30,170 --> 00:03:27,480 many of those ideas are now having to be 64 00:03:31,940 --> 00:03:30,180 cast aside as we as we see orbital data 65 00:03:35,180 --> 00:03:31,950 for the first time we are confirming a 66 00:03:38,449 --> 00:03:35,190 few of the theories that have preceded 67 00:03:40,880 --> 00:03:38,459 us but many of those theories are now 68 00:03:46,490 --> 00:03:40,890 being cast into the dustbin of science 69 00:03:48,320 --> 00:03:46,500 as they are shown to be very incomplete 70 00:03:50,240 --> 00:03:48,330 or incorrect description of the 71 00:03:52,690 --> 00:03:50,250 innermost planet you'll hear examples of 72 00:03:55,699 --> 00:03:52,700 those from each of the presenters today 73 00:03:57,830 --> 00:03:55,709 one of our instruments on the spacecraft 74 00:04:00,979 --> 00:03:57,840 is of course our imaging system we've 75 00:04:04,370 --> 00:04:00,989 taken more than 20,000 images of mercury 76 00:04:06,440 --> 00:04:04,380 to date and I'd like to turn the 77 00:04:07,910 --> 00:04:06,450 microphone over to my colleague Benton 78 00:04:09,229 --> 00:04:07,920 every who will describe some of the 79 00:04:12,290 --> 00:04:09,239 things we're learning from those images 80 00:04:14,479 --> 00:04:12,300 but Thank You Sean well it's my 81 00:04:16,729 --> 00:04:14,489 privilege today to share some of our 82 00:04:19,280 --> 00:04:16,739 early science results from the orbital 83 00:04:24,290 --> 00:04:19,290 imaging campaign if we can pull up the 84 00:04:26,750 --> 00:04:24,300 first image this is a view of mercury 85 00:04:28,580 --> 00:04:26,760 looking down on the North Pole 86 00:04:30,680 --> 00:04:28,590 and this is an area that we didn't 87 00:04:33,710 --> 00:04:30,690 really have great coverage of before due 88 00:04:36,050 --> 00:04:33,720 to the nature of flybys so you can see 89 00:04:39,110 --> 00:04:36,060 on the left half there it's mostly all 90 00:04:40,790 --> 00:04:39,120 of our new orbital coverage where we 91 00:04:43,010 --> 00:04:40,800 filled in pretty much all of the gaps 92 00:04:44,390 --> 00:04:43,020 consistently on the right hand side we 93 00:04:46,850 --> 00:04:44,400 haven't yet marched all the way around 94 00:04:49,370 --> 00:04:46,860 the planet to fill that in so it's still 95 00:04:50,920 --> 00:04:49,380 showing some of our flyby coverage but 96 00:04:54,830 --> 00:04:50,930 what you can see there in yellow 97 00:04:57,890 --> 00:04:54,840 outlined is the approximate extent of a 98 00:05:00,380 --> 00:04:57,900 really large unit of smooth Plains and 99 00:05:03,770 --> 00:05:00,390 these planes are thought to be volcanic 100 00:05:05,840 --> 00:05:03,780 in origin and we had some hints from the 101 00:05:09,410 --> 00:05:05,850 flybys mariner 10 actually got the best 102 00:05:11,030 --> 00:05:09,420 look of these planes but now we're 103 00:05:14,780 --> 00:05:11,040 seeing for the first time their full 104 00:05:17,720 --> 00:05:14,790 extent which is around 4 million square 105 00:05:23,420 --> 00:05:17,730 kilometers surround half the size of the 106 00:05:26,150 --> 00:05:23,430 continental US and if we can go to the 107 00:05:28,340 --> 00:05:26,160 next graphic you can see this is just an 108 00:05:31,220 --> 00:05:28,350 example of how we actually did see some 109 00:05:32,870 --> 00:05:31,230 of these planes during the flybys but 110 00:05:35,360 --> 00:05:32,880 because we're flying by close to the 111 00:05:37,280 --> 00:05:35,370 equator looking up at high latitudes is 112 00:05:39,470 --> 00:05:37,290 really a difficult challenge and so 113 00:05:44,030 --> 00:05:39,480 orbit is perfect for that if you can add 114 00:05:46,850 --> 00:05:44,040 the overlay there you'll see this is the 115 00:05:48,320 --> 00:05:46,860 same area as seen from our flyby images 116 00:05:51,980 --> 00:05:48,330 where we can look straight down on the 117 00:05:54,140 --> 00:05:51,990 surface and so from our more detailed 118 00:05:56,120 --> 00:05:54,150 look at this beautiful large unit of 119 00:05:58,430 --> 00:05:56,130 smooth Plains we're seeing all kinds of 120 00:06:01,220 --> 00:05:58,440 evidence for volcanism the tectonic 121 00:06:02,960 --> 00:06:01,230 deformation of these planes in this 122 00:06:04,700 --> 00:06:02,970 image toward the center and on the right 123 00:06:07,010 --> 00:06:04,710 side they're actually you can see ghosts 124 00:06:09,770 --> 00:06:07,020 craters which are pre-existing impact 125 00:06:12,740 --> 00:06:09,780 craters that were later covered over by 126 00:06:15,890 --> 00:06:12,750 lava and you can just see their rims 127 00:06:18,710 --> 00:06:15,900 affecting the structures there if you 128 00:06:21,710 --> 00:06:18,720 can bring up the next image please we're 129 00:06:24,260 --> 00:06:21,720 also orbiting in our orbital coverage 130 00:06:26,840 --> 00:06:24,270 we're collecting color images through 131 00:06:29,330 --> 00:06:26,850 eight color filters of the whole planet 132 00:06:32,300 --> 00:06:29,340 with a resolution of around a kilometer 133 00:06:35,300 --> 00:06:32,310 per pixel and so the reason we image 134 00:06:36,830 --> 00:06:35,310 mercury in color is so that we can try 135 00:06:38,540 --> 00:06:36,840 to understand it's composition the 136 00:06:39,460 --> 00:06:38,550 colors of the surfaces are related to 137 00:06:43,870 --> 00:06:39,470 the 138 00:06:45,760 --> 00:06:43,880 surface and so this image is also 139 00:06:48,880 --> 00:06:45,770 showing the smooth Plains there the less 140 00:06:52,240 --> 00:06:48,890 cratered area that shows up as kind of 141 00:06:54,820 --> 00:06:52,250 an orange or red in this color scheme if 142 00:06:58,660 --> 00:06:54,830 you bring up the next image the last 143 00:07:02,050 --> 00:06:58,670 image sorry was in an image where the 144 00:07:03,640 --> 00:07:02,060 infra red red and blue filters were in 145 00:07:06,520 --> 00:07:03,650 the red green and blue channels this 146 00:07:09,730 --> 00:07:06,530 image is an enhanced color look at the 147 00:07:12,670 --> 00:07:09,740 same region that just shows these smooth 148 00:07:14,080 --> 00:07:12,680 Plains are compositionally distinct from 149 00:07:15,790 --> 00:07:14,090 their surroundings and while we don't 150 00:07:18,790 --> 00:07:15,800 yet know their composition that's 151 00:07:20,610 --> 00:07:18,800 something we're working on but we're 152 00:07:23,380 --> 00:07:20,620 really excited to keep studying this 153 00:07:26,980 --> 00:07:23,390 huge volcanic deposit near the North 154 00:07:29,220 --> 00:07:26,990 Pole its implications for the evolution 155 00:07:34,720 --> 00:07:29,230 of Mercury's crust and how it formed 156 00:07:37,810 --> 00:07:34,730 next slide please this is just showing 157 00:07:41,500 --> 00:07:37,820 our coverage so far that we've obtained 158 00:07:44,950 --> 00:07:41,510 from orbit in our monochrome mapping 159 00:07:46,510 --> 00:07:44,960 campaign so you can see in just around 160 00:07:48,460 --> 00:07:46,520 three months less than three months 161 00:07:50,560 --> 00:07:48,470 we've filled in a great deal of the 162 00:07:54,400 --> 00:07:50,570 planet already at least for this 163 00:07:56,200 --> 00:07:54,410 hemisphere if you can start the movie 164 00:07:57,940 --> 00:07:56,210 when you zoom in here you can see if 165 00:08:00,760 --> 00:07:57,950 this images are collected at an average 166 00:08:03,280 --> 00:08:00,770 resolution of around 250 meters per 167 00:08:05,530 --> 00:08:03,290 pixel and when you zoom into the full 168 00:08:06,880 --> 00:08:05,540 resolution you can start to see this is 169 00:08:11,320 --> 00:08:06,890 just one of the many spectacular 170 00:08:14,590 --> 00:08:11,330 features on Mercury this is a 13 171 00:08:17,770 --> 00:08:14,600 kilometer impact crater and that dark 172 00:08:20,320 --> 00:08:17,780 region that you see to the south is 173 00:08:23,350 --> 00:08:20,330 impact melt which flowed from the crater 174 00:08:26,170 --> 00:08:23,360 impact mount forms when the impact 175 00:08:28,630 --> 00:08:26,180 occurs the temperatures and pressures 176 00:08:31,750 --> 00:08:28,640 are very high they melt the rock on the 177 00:08:35,610 --> 00:08:31,760 surface and it can flow in this case 178 00:08:39,100 --> 00:08:35,620 away from the crater and this particular 179 00:08:41,620 --> 00:08:39,110 view here shows the impact melt is very 180 00:08:43,540 --> 00:08:41,630 dark the color imaging and also the 181 00:08:45,610 --> 00:08:43,550 reflectance spectrometer on messenger 182 00:08:47,740 --> 00:08:45,620 hint that this may be a unique 183 00:08:49,690 --> 00:08:47,750 composition distinct from its 184 00:08:51,820 --> 00:08:49,700 surroundings and definitely different 185 00:08:52,960 --> 00:08:51,830 from most of the typical impact mounts 186 00:08:58,019 --> 00:08:52,970 that we see on 187 00:09:02,610 --> 00:08:58,029 hurry next please in addition to our 188 00:09:05,829 --> 00:09:02,620 standard color and monochrome mapping 189 00:09:08,499 --> 00:09:05,839 imaging campaigns we also are able to 190 00:09:11,439 --> 00:09:08,509 collect high-resolution targeted images 191 00:09:13,210 --> 00:09:11,449 for regions that are of high scientific 192 00:09:15,360 --> 00:09:13,220 interest things that we saw during the 193 00:09:18,220 --> 00:09:15,370 flybys and wanted to get a better look 194 00:09:20,470 --> 00:09:18,230 this is showing the cratered agha which 195 00:09:23,679 --> 00:09:20,480 is around 50 kilometers in diameter on 196 00:09:27,400 --> 00:09:23,689 the left-hand side you'll see that was 197 00:09:29,980 --> 00:09:27,410 the coverage from Mariner 10 and so our 198 00:09:33,939 --> 00:09:29,990 targeted images and color here are 199 00:09:36,009 --> 00:09:33,949 acquiring a great new level of detail 200 00:09:38,499 --> 00:09:36,019 you can see on this crater there's 201 00:09:40,869 --> 00:09:38,509 impact mount that covers the floor it 202 00:09:43,179 --> 00:09:40,879 has these fractures that formed as the 203 00:09:45,910 --> 00:09:43,189 impact melt cooled and solidified and 204 00:09:48,009 --> 00:09:45,920 cracked and then the beautiful bright 205 00:09:52,740 --> 00:09:48,019 area in the center is the central peak 206 00:09:55,269 --> 00:09:52,750 complex there in the next slide please 207 00:09:58,179 --> 00:09:55,279 we're also able to acquire targeted 208 00:09:59,799 --> 00:09:58,189 monochrome images and this is a great 209 00:10:02,619 --> 00:09:59,809 example of the importance of these 210 00:10:05,199 --> 00:10:02,629 high-resolution images messenger can 211 00:10:08,470 --> 00:10:05,209 acquire images at up to 10 meters per 212 00:10:12,100 --> 00:10:08,480 pixel this one here is 21 meters per 213 00:10:15,240 --> 00:10:12,110 pixel and it shows a region that we saw 214 00:10:18,759 --> 00:10:15,250 these areas during the flybys that had 215 00:10:21,759 --> 00:10:18,769 patchy bright material on crater floors 216 00:10:23,889 --> 00:10:21,769 sometimes in peak rings of craters and 217 00:10:25,809 --> 00:10:23,899 we simply didn't have the ability to 218 00:10:27,549 --> 00:10:25,819 determine what they were because we 219 00:10:30,490 --> 00:10:27,559 couldn't see it at any higher resolution 220 00:10:34,119 --> 00:10:30,500 we look at these targeted images we can 221 00:10:36,850 --> 00:10:34,129 see that these patchy bright regions are 222 00:10:39,699 --> 00:10:36,860 actually a train that appears to be 223 00:10:42,999 --> 00:10:39,709 etched there are clusters of small 224 00:10:45,780 --> 00:10:43,009 rimless depressions a few hundred metres 225 00:10:51,460 --> 00:10:45,790 to a kilometre they often have diffuse 226 00:10:53,199 --> 00:10:51,470 bright halos around them the line on the 227 00:10:55,449 --> 00:10:53,209 bottom image where you can see kind of a 228 00:10:57,910 --> 00:10:55,459 line of these little pits and etch 229 00:11:02,410 --> 00:10:57,920 terrain that's actually the peak ring of 230 00:11:04,329 --> 00:11:02,420 an impact crater and so we still aren't 231 00:11:05,350 --> 00:11:04,339 sure how these are formed how these 232 00:11:07,870 --> 00:11:05,360 formed 233 00:11:11,110 --> 00:11:07,880 there are a couple ideas when you see 234 00:11:13,990 --> 00:11:11,120 rimless depressions like this in other 235 00:11:16,690 --> 00:11:14,000 places they're often due to an explosive 236 00:11:19,269 --> 00:11:16,700 volcanic eruption where you have a gas 237 00:11:22,630 --> 00:11:19,279 that when it gets near the surface in 238 00:11:26,319 --> 00:11:22,640 the magma expands explodes like mount 239 00:11:28,949 --> 00:11:26,329 st. helens for example but these 240 00:11:32,530 --> 00:11:28,959 features do appear quite different from 241 00:11:34,630 --> 00:11:32,540 the typical vents that we see on the 242 00:11:38,620 --> 00:11:34,640 moon or on Mercury they're really unlike 243 00:11:41,170 --> 00:11:38,630 anything we've seen before so another 244 00:11:43,870 --> 00:11:41,180 idea is that they contain some kind of 245 00:11:46,000 --> 00:11:43,880 material or compound that is not stable 246 00:11:50,009 --> 00:11:46,010 when it's exposed near the surface of 247 00:11:53,019 --> 00:11:50,019 mercury so a volatile material that 248 00:11:55,360 --> 00:11:53,029 evaporates or sublimes when exposed at 249 00:11:57,400 --> 00:11:55,370 the surface so we're really excited to 250 00:12:00,610 --> 00:11:57,410 keep studying these features try and 251 00:12:01,990 --> 00:12:00,620 understand their origin apply data from 252 00:12:05,139 --> 00:12:02,000 all of the other instruments on 253 00:12:08,949 --> 00:12:05,149 messenger and with that I'll pass to 254 00:12:10,930 --> 00:12:08,959 Larry Thank You Bret I'm very happy to 255 00:12:13,090 --> 00:12:10,940 be here today I'm going to talk about 256 00:12:14,710 --> 00:12:13,100 results we've gotten from to specific 257 00:12:16,240 --> 00:12:14,720 instruments on messenger the x-ray 258 00:12:18,040 --> 00:12:16,250 spectrometer and the gamma-ray and 259 00:12:21,400 --> 00:12:18,050 neutron spectrometer these instruments 260 00:12:22,960 --> 00:12:21,410 are designed to measure the abundances 261 00:12:25,210 --> 00:12:22,970 of the chemical elements at the surface 262 00:12:27,519 --> 00:12:25,220 of mercury now the abundances of 263 00:12:29,110 --> 00:12:27,529 elements on planets depends on the what 264 00:12:30,699 --> 00:12:29,120 the planets were originally made out of 265 00:12:33,639 --> 00:12:30,709 their entire geological history so 266 00:12:38,019 --> 00:12:33,649 they're very diagnostic of important 267 00:12:39,819 --> 00:12:38,029 processes over the years many ideas and 268 00:12:41,439 --> 00:12:39,829 models have been put forward about what 269 00:12:43,600 --> 00:12:41,449 the composition of mercury might be 270 00:12:46,689 --> 00:12:43,610 based on various formation models and 271 00:12:49,300 --> 00:12:46,699 evolution models and but it was only 272 00:12:50,740 --> 00:12:49,310 until now that messenger is in orbit 273 00:12:52,900 --> 00:12:50,750 around the planet that we can actually 274 00:12:55,630 --> 00:12:52,910 start testing these models in detail and 275 00:12:59,199 --> 00:12:55,640 really see if any of them are right and 276 00:13:01,750 --> 00:12:59,209 what we were finding is Sean indicated 277 00:13:03,250 --> 00:13:01,760 is that in many cases a lot of the 278 00:13:05,230 --> 00:13:03,260 original ideas about mercury are just 279 00:13:07,360 --> 00:13:05,240 plain wrong and so we're finding some 280 00:13:09,370 --> 00:13:07,370 surprises and we're getting very 281 00:13:12,069 --> 00:13:09,380 interesting results as I'll show you so 282 00:13:14,740 --> 00:13:12,079 this first animation is an illustration 283 00:13:17,590 --> 00:13:14,750 of how one of these instruments works 284 00:13:19,240 --> 00:13:17,600 the x-ray spectrometer now we use this 285 00:13:21,430 --> 00:13:19,250 instrument basically x-rays 286 00:13:22,810 --> 00:13:21,440 from the Sun are emitted by high 287 00:13:24,940 --> 00:13:22,820 temperature plasma and the outer 288 00:13:28,090 --> 00:13:24,950 atmosphere of the Sun these x-rays hit 289 00:13:29,800 --> 00:13:28,100 the planet and they can be cause rhea 290 00:13:31,750 --> 00:13:29,810 mission of fluorescent x-rays this is 291 00:13:34,420 --> 00:13:31,760 very much like a blacklight poster 292 00:13:36,430 --> 00:13:34,430 glowing under a UV lamp so it's a 293 00:13:38,020 --> 00:13:36,440 fluorescent process these x-rays can be 294 00:13:40,780 --> 00:13:38,030 detected by the instrument onboard the 295 00:13:42,730 --> 00:13:40,790 spacecraft and used to determine what 296 00:13:46,570 --> 00:13:42,740 elements are present and in what 297 00:13:48,700 --> 00:13:46,580 abundance so this technique depends as I 298 00:13:50,740 --> 00:13:48,710 said on the x rays from the Sun the 299 00:13:53,830 --> 00:13:50,750 solar x-ray emission varies with time 300 00:13:55,330 --> 00:13:53,840 wildly and gets especially high during 301 00:13:56,770 --> 00:13:55,340 large solar flares well we've been 302 00:13:58,450 --> 00:13:56,780 fortunate that the Sun has been 303 00:14:00,880 --> 00:13:58,460 relatively active since we went into 304 00:14:03,460 --> 00:14:00,890 orbit three months ago so we've gotten 305 00:14:04,870 --> 00:14:03,470 some very good fluorescent to x-ray data 306 00:14:06,520 --> 00:14:04,880 from the surface so we're getting good 307 00:14:08,890 --> 00:14:06,530 measurements right now of the average 308 00:14:11,110 --> 00:14:08,900 composition of key elements like 309 00:14:13,060 --> 00:14:11,120 magnesium aluminum silicon sulfur 310 00:14:15,340 --> 00:14:13,070 calcium titanium and iron with this 311 00:14:19,390 --> 00:14:15,350 instrument so as an example may have the 312 00:14:21,550 --> 00:14:19,400 next slide please this shows the a graph 313 00:14:23,770 --> 00:14:21,560 of the magnesium to silicon ratio 314 00:14:25,720 --> 00:14:23,780 plotted against the aluminum to silicon 315 00:14:27,579 --> 00:14:25,730 ratio for different types of rocks on 316 00:14:30,250 --> 00:14:27,589 the earth and on the moon and on Mars 317 00:14:31,720 --> 00:14:30,260 now you can see is that these different 318 00:14:33,640 --> 00:14:31,730 types of rocks and planets have 319 00:14:35,650 --> 00:14:33,650 different lie in different places on 320 00:14:36,910 --> 00:14:35,660 this plot and so it's a good 321 00:14:38,860 --> 00:14:36,920 discriminant of pot of different 322 00:14:40,450 --> 00:14:38,870 processes for example at the bottom 323 00:14:42,520 --> 00:14:40,460 right you can see that rocks from the 324 00:14:44,770 --> 00:14:42,530 interior of the earth are relatively 325 00:14:47,680 --> 00:14:44,780 enriched in magnesium and depleted in 326 00:14:49,329 --> 00:14:47,690 aluminum compared to typical rocks on 327 00:14:51,040 --> 00:14:49,339 the surface of the earth like basalts 328 00:14:52,870 --> 00:14:51,050 that can be seen at the sort of middle 329 00:14:55,930 --> 00:14:52,880 left with higher aluminum and lower 330 00:14:57,460 --> 00:14:55,940 magnesium many many rocks on the surface 331 00:15:00,130 --> 00:14:57,470 of the Moon are even more enriched in 332 00:15:01,480 --> 00:15:00,140 aluminum than typical earth rocks so 333 00:15:05,230 --> 00:15:01,490 there are up in the upper left portion 334 00:15:07,930 --> 00:15:05,240 of this diagram and that reflects a very 335 00:15:10,600 --> 00:15:07,940 high abundance of minerals feldspar 336 00:15:12,130 --> 00:15:10,610 minerals so if we end on this graph we 337 00:15:13,750 --> 00:15:12,140 can also see that Mars occupies an 338 00:15:15,460 --> 00:15:13,760 entirely different region on this plot 339 00:15:17,800 --> 00:15:15,470 so different planets lie in different 340 00:15:19,870 --> 00:15:17,810 regions and where there's mercury lie 341 00:15:22,090 --> 00:15:19,880 well if I have the next slide this shows 342 00:15:24,520 --> 00:15:22,100 our data that we're determining from the 343 00:15:26,530 --> 00:15:24,530 x-ray spectrometer the lighter symbols 344 00:15:28,120 --> 00:15:26,540 indicate measurements over very large 345 00:15:30,970 --> 00:15:28,130 area sort of one to two thousand 346 00:15:32,620 --> 00:15:30,980 kilometer footprint size whereas the 347 00:15:33,220 --> 00:15:32,630 darker symbols are slightly better 348 00:15:35,080 --> 00:15:33,230 resolved 349 00:15:37,240 --> 00:15:35,090 measurements down to a few hundred 350 00:15:39,370 --> 00:15:37,250 kilometers and what's clear here is the 351 00:15:41,260 --> 00:15:39,380 mercury is not the moon and it's not the 352 00:15:43,600 --> 00:15:41,270 earth the surface of mercury occupies a 353 00:15:45,630 --> 00:15:43,610 fairly unique location on this diagram 354 00:15:48,610 --> 00:15:45,640 for the surfaces of terrestrial planets 355 00:15:50,830 --> 00:15:48,620 it's got lower aluminum and more 356 00:15:53,290 --> 00:15:50,840 magnesium relative to silicon so it has 357 00:15:55,390 --> 00:15:53,300 a lower abundance of feldspar and it 358 00:15:58,210 --> 00:15:55,400 clearly is undergone a unique geological 359 00:16:00,400 --> 00:15:58,220 history in addition to these data the 360 00:16:03,070 --> 00:16:00,410 x-ray spectrometers made two additional 361 00:16:05,110 --> 00:16:03,080 very interesting observations first we 362 00:16:07,690 --> 00:16:05,120 have found that the surface of mercury 363 00:16:10,720 --> 00:16:07,700 Israel has relatively low abundances of 364 00:16:12,220 --> 00:16:10,730 iron and titanium now it's been known 365 00:16:15,580 --> 00:16:12,230 for many years from ground-based 366 00:16:17,290 --> 00:16:15,590 spectral observations of mercury that 367 00:16:19,080 --> 00:16:17,300 the silicate minerals at the surface of 368 00:16:22,600 --> 00:16:19,090 the planet are low in iron and titanium 369 00:16:25,900 --> 00:16:22,610 but data from the flybys of messenger of 370 00:16:27,970 --> 00:16:25,910 mercury suggested that there in fact 371 00:16:29,620 --> 00:16:27,980 could be much higher abundances of iron 372 00:16:31,030 --> 00:16:29,630 and titanium at the surface that just 373 00:16:33,640 --> 00:16:31,040 were not in silicates we're in other 374 00:16:35,140 --> 00:16:33,650 phases well the x-ray data clearly 375 00:16:36,850 --> 00:16:35,150 showed this is not the case that the 376 00:16:39,460 --> 00:16:36,860 rocky part of the planet is low in iron 377 00:16:41,200 --> 00:16:39,470 and titanium so it shows it helps show 378 00:16:42,850 --> 00:16:41,210 the power of orbital missions versus 379 00:16:45,910 --> 00:16:42,860 flybys that even when you get excellent 380 00:16:47,950 --> 00:16:45,920 data on flybys it's not always easy to 381 00:16:49,720 --> 00:16:47,960 unambiguously interpret it so here in 382 00:16:51,580 --> 00:16:49,730 the orbit we're getting this and again 383 00:16:53,170 --> 00:16:51,590 it shows that mercury is different from 384 00:16:54,610 --> 00:16:53,180 the other planets which have much more 385 00:16:56,890 --> 00:16:54,620 iron and titanium in their rocky 386 00:16:59,110 --> 00:16:56,900 portions the other very interesting 387 00:17:00,730 --> 00:16:59,120 observation that we've found is that the 388 00:17:03,040 --> 00:17:00,740 data revealed that the surface of 389 00:17:05,110 --> 00:17:03,050 mercury has a very high relatively high 390 00:17:07,150 --> 00:17:05,120 sulphur abundance on the order of a few 391 00:17:09,310 --> 00:17:07,160 percent by weight of the surface of 392 00:17:10,720 --> 00:17:09,320 mercury appears to be sulfur which is at 393 00:17:13,810 --> 00:17:10,730 least a factor of ten times higher than 394 00:17:15,610 --> 00:17:13,820 the crust of the earth or the moon we do 395 00:17:17,680 --> 00:17:15,620 not fully understand this yet but it 396 00:17:19,630 --> 00:17:17,690 almost certainly relates to the origin 397 00:17:21,580 --> 00:17:19,640 of mercury that mercury most likely 398 00:17:23,170 --> 00:17:21,590 formed from building blocks that were 399 00:17:24,370 --> 00:17:23,180 fundamentally chemically different from 400 00:17:27,550 --> 00:17:24,380 those that form the Earth and Moon 401 00:17:29,110 --> 00:17:27,560 originally it also has important 402 00:17:30,670 --> 00:17:29,120 implications for understanding volcanism 403 00:17:32,200 --> 00:17:30,680 as bread was talking about we have 404 00:17:36,400 --> 00:17:32,210 evidence for explosive volcanism 405 00:17:39,190 --> 00:17:36,410 possibly driven by its volatile gases 406 00:17:41,440 --> 00:17:39,200 and on the earth these are and this is 407 00:17:43,180 --> 00:17:41,450 often driven by sulfur bearing volatile 408 00:17:45,580 --> 00:17:43,190 gases and so the presence of sulfur 409 00:17:47,070 --> 00:17:45,590 should tell us new things about the 410 00:17:50,170 --> 00:17:47,080 nature of volcanism on mark 411 00:17:52,840 --> 00:17:50,180 so shifting gears have the next 412 00:17:54,340 --> 00:17:52,850 animation please so this is an 413 00:17:56,140 --> 00:17:54,350 illustration of the other instrument the 414 00:17:58,390 --> 00:17:56,150 gamma ray and neutron spectrometer which 415 00:18:00,610 --> 00:17:58,400 which probes material to depths of a few 416 00:18:03,520 --> 00:18:00,620 hundred or few tens of centimeters of 417 00:18:04,810 --> 00:18:03,530 few feet and basically this instrument 418 00:18:06,790 --> 00:18:04,820 works when galactic cosmic rays 419 00:18:08,590 --> 00:18:06,800 streaming through space interact with 420 00:18:10,690 --> 00:18:08,600 the surface they make neutrons they can 421 00:18:12,040 --> 00:18:10,700 be fast high energy or slow and then 422 00:18:14,440 --> 00:18:12,050 they can get slowed down to be thermal 423 00:18:17,170 --> 00:18:14,450 neutrons these neutrons can interact 424 00:18:18,910 --> 00:18:17,180 with materials at the surface to produce 425 00:18:21,100 --> 00:18:18,920 gamma rays that are have energies 426 00:18:22,540 --> 00:18:21,110 characteristic of the elements and in 427 00:18:24,130 --> 00:18:22,550 addition if you have naturally 428 00:18:26,850 --> 00:18:24,140 radioactive elements like potassium 429 00:18:29,740 --> 00:18:26,860 thorium and uranium they can decay 430 00:18:31,180 --> 00:18:29,750 naturally and release gamma rays and all 431 00:18:32,830 --> 00:18:31,190 of these neutrons and gamma rays can be 432 00:18:34,480 --> 00:18:32,840 detected by the instrument onboard the 433 00:18:36,940 --> 00:18:34,490 spacecraft and used to determine the 434 00:18:38,680 --> 00:18:36,950 composition of the planet I'm going to 435 00:18:40,000 --> 00:18:38,690 focus today on the results for potassium 436 00:18:42,040 --> 00:18:40,010 and thorium both of which have 437 00:18:43,900 --> 00:18:42,050 radioactive isotopes so we can detect 438 00:18:48,760 --> 00:18:43,910 their abundances may have the next slide 439 00:18:52,270 --> 00:18:48,770 please so the ratio of potassium to 440 00:18:54,370 --> 00:18:52,280 thorium has long been understood to be a 441 00:18:56,530 --> 00:18:54,380 very useful probe in planetary science 442 00:18:59,530 --> 00:18:56,540 and the reason for this is potassium is 443 00:19:00,970 --> 00:18:59,540 a rather volatile element so it 444 00:19:05,350 --> 00:19:00,980 evaporates at relatively low temperature 445 00:19:07,360 --> 00:19:05,360 and thorium does not so the ratio of 446 00:19:09,100 --> 00:19:07,370 these two elements can provide great a 447 00:19:10,930 --> 00:19:09,110 great deal of information about thermal 448 00:19:12,490 --> 00:19:10,940 heating processes that occurred in the 449 00:19:15,160 --> 00:19:12,500 early solar system when these planets 450 00:19:18,490 --> 00:19:15,170 were coming together so this plot shows 451 00:19:20,680 --> 00:19:18,500 the potassium to thorium for Venus the 452 00:19:22,270 --> 00:19:20,690 Earth and Moon system and Mars and a 453 00:19:24,340 --> 00:19:22,280 striking thing on here is that the moon 454 00:19:25,840 --> 00:19:24,350 has a much lower ratio of potassium to 455 00:19:27,760 --> 00:19:25,850 thorium than the other planets and this 456 00:19:29,050 --> 00:19:27,770 is a direct reflection of the very very 457 00:19:31,450 --> 00:19:29,060 high temperatures that the moon 458 00:19:33,550 --> 00:19:31,460 experienced when it formed by a giant 459 00:19:35,620 --> 00:19:33,560 impact of a mars-sized impactor on the 460 00:19:37,720 --> 00:19:35,630 earth and it got so hot that they've 461 00:19:40,540 --> 00:19:37,730 potassium and other volatile elements 462 00:19:42,610 --> 00:19:40,550 like it essentially evaporated away well 463 00:19:44,950 --> 00:19:42,620 prior to messenger many ideas about 464 00:19:46,870 --> 00:19:44,960 mercury suggested that it should also 465 00:19:49,090 --> 00:19:46,880 have a low potassium to thorium ratio 466 00:19:50,980 --> 00:19:49,100 mercury formed very close to the Sun in 467 00:19:53,740 --> 00:19:50,990 the early solar system was thought that 468 00:19:55,750 --> 00:19:53,750 the nebula from which the the disk from 469 00:19:58,630 --> 00:19:55,760 which the solar system formed the 470 00:20:00,760 --> 00:19:58,640 planets formed a was hot there and very 471 00:20:02,350 --> 00:20:00,770 light there are many formation 472 00:20:04,390 --> 00:20:02,360 models for mercury that suggested this 473 00:20:06,220 --> 00:20:04,400 ratio should be low but in fact the 474 00:20:08,620 --> 00:20:06,230 gamma ray results show the opposite may 475 00:20:10,510 --> 00:20:08,630 have the next slide please they've been 476 00:20:13,090 --> 00:20:10,520 able to measure this ratio on mercury 477 00:20:14,710 --> 00:20:13,100 and surprisingly it's not low it's in 478 00:20:16,480 --> 00:20:14,720 fact as high or higher than that of the 479 00:20:18,670 --> 00:20:16,490 other terrestrial planets so this tells 480 00:20:20,590 --> 00:20:18,680 us right away that mercury is not highly 481 00:20:22,600 --> 00:20:20,600 depleted in these kinds of volatile 482 00:20:24,700 --> 00:20:22,610 elements unlike previous ideas it rules 483 00:20:25,720 --> 00:20:24,710 out some formation models and it's 484 00:20:27,430 --> 00:20:25,730 completely consistent with other 485 00:20:29,230 --> 00:20:27,440 observations like the high abundance of 486 00:20:31,570 --> 00:20:29,240 sulfur which is also a relatively 487 00:20:33,250 --> 00:20:31,580 volatile element and the presence of 488 00:20:36,430 --> 00:20:33,260 sodium which has been observed over the 489 00:20:38,530 --> 00:20:36,440 years in the exosphere around mercury 490 00:20:40,330 --> 00:20:38,540 and has clearly been coming from the 491 00:20:42,880 --> 00:20:40,340 surface so there are there seem to be a 492 00:20:46,780 --> 00:20:42,890 large amount of volatile elements in the 493 00:20:49,210 --> 00:20:46,790 planet and all taken altogether these 494 00:20:51,280 --> 00:20:49,220 elements are changing our view of the 495 00:20:52,930 --> 00:20:51,290 origin of mercury it indicates the 496 00:20:55,540 --> 00:20:52,940 mercury is not the earth that is not the 497 00:20:56,770 --> 00:20:55,550 moon and we're going to use these data 498 00:20:58,510 --> 00:20:56,780 in conjunction with all the other 499 00:21:00,220 --> 00:20:58,520 observations to truly try and better 500 00:21:01,660 --> 00:21:00,230 understand how the planet formed what it 501 00:21:03,460 --> 00:21:01,670 formed from and what has happened to it 502 00:21:07,180 --> 00:21:03,470 in the immediate four-and-a-half billion 503 00:21:09,610 --> 00:21:07,190 years and with that I will pass it on to 504 00:21:11,920 --> 00:21:09,620 shot Thank You Larry I'd like to share 505 00:21:13,810 --> 00:21:11,930 some of our recent findings from two 506 00:21:16,750 --> 00:21:13,820 different investigations from the 507 00:21:19,150 --> 00:21:16,760 messenger mission the measurement of the 508 00:21:21,250 --> 00:21:19,160 topography of the surface of mercury and 509 00:21:23,590 --> 00:21:21,260 the measurement of Mercury's internal 510 00:21:26,050 --> 00:21:23,600 magnetic field if we could go to the 511 00:21:27,850 --> 00:21:26,060 first animation you'll see a very 512 00:21:30,640 --> 00:21:27,860 schematic depiction of the operation of 513 00:21:33,340 --> 00:21:30,650 Mercury's messenger laser mercury laser 514 00:21:35,650 --> 00:21:33,350 altimeter that sends eight times the 515 00:21:39,190 --> 00:21:35,660 second a short pulse from a powerful 516 00:21:41,740 --> 00:21:39,200 laser and it records the reflection of 517 00:21:43,450 --> 00:21:41,750 that laser pulse off the surface and 518 00:21:46,420 --> 00:21:43,460 from the time of flight of the laser 519 00:21:48,220 --> 00:21:46,430 signal and from precise knowledge of the 520 00:21:50,650 --> 00:21:48,230 position of the spacecraft it determines 521 00:21:52,450 --> 00:21:50,660 a topographic profile underneath the 522 00:21:54,520 --> 00:21:52,460 path of the spacecraft while we're 523 00:21:56,950 --> 00:21:54,530 switching to the next animation let me 524 00:21:59,230 --> 00:21:56,960 say that that laser altimeter has 525 00:22:02,350 --> 00:21:59,240 operated more than two million times 526 00:22:06,570 --> 00:22:02,360 from orbit so far and what do you see 527 00:22:09,630 --> 00:22:06,580 playing out on this animation our tracks 528 00:22:11,860 --> 00:22:09,640 color-coded by elevation of the 529 00:22:14,020 --> 00:22:11,870 topography of the northern hemisphere of 530 00:22:14,560 --> 00:22:14,030 mercury we're seeing the broad shape of 531 00:22:16,480 --> 00:22:14,570 the planet 532 00:22:19,210 --> 00:22:16,490 for the first time we're seeing detailed 533 00:22:23,740 --> 00:22:19,220 profiles of geological features impact 534 00:22:26,430 --> 00:22:23,750 craters and basins fault scarps volcanic 535 00:22:29,409 --> 00:22:26,440 terrain you're seeing that the northern 536 00:22:31,840 --> 00:22:29,419 region of the planet is surprisingly low 537 00:22:34,149 --> 00:22:31,850 the area of the of the Northern Plains 538 00:22:36,580 --> 00:22:34,159 that Bret talked about has some quite 539 00:22:38,560 --> 00:22:36,590 low but variable elevations several 540 00:22:41,590 --> 00:22:38,570 kilometres below that for the average of 541 00:22:45,279 --> 00:22:41,600 the planet the total range in elevation 542 00:22:48,009 --> 00:22:45,289 is as much as 9 kilometers on the basis 543 00:22:50,139 --> 00:22:48,019 of observations to date one of the 544 00:22:52,930 --> 00:22:50,149 investigations that we're using alt 545 00:22:55,960 --> 00:22:52,940 imagery to pursue is a 20-year old 546 00:22:58,690 --> 00:22:55,970 mystery that was set by earth-based 547 00:23:03,369 --> 00:22:58,700 radar observations in the next graphic 548 00:23:05,049 --> 00:23:03,379 shows a modern radar image of a portion 549 00:23:07,299 --> 00:23:05,059 of the north polar region of mercury 550 00:23:10,060 --> 00:23:07,309 obtained at the Arecibo Observatory in 551 00:23:12,820 --> 00:23:10,070 Puerto Rico what you see are bright 552 00:23:14,440 --> 00:23:12,830 deposits that radar wavelengths that are 553 00:23:15,519 --> 00:23:14,450 thought on the basis of the radar 554 00:23:18,180 --> 00:23:15,529 characteristics this is a 555 00:23:21,509 --> 00:23:18,190 twenty-year-old proposal to be water ice 556 00:23:24,909 --> 00:23:21,519 this on the planet closest to the Sun 557 00:23:26,980 --> 00:23:24,919 now yep planet gets very hot at the 558 00:23:29,950 --> 00:23:26,990 equator in the daytime so how can there 559 00:23:32,200 --> 00:23:29,960 be water ice at the poles of mercury the 560 00:23:34,899 --> 00:23:32,210 hypothesis now going back 20 years is 561 00:23:37,450 --> 00:23:34,909 that that water ice resides and on the 562 00:23:39,730 --> 00:23:37,460 floors of impact craters that are in 563 00:23:41,649 --> 00:23:39,740 permanent shadow that never see sunlight 564 00:23:44,110 --> 00:23:41,659 and therefore are extraordinarily cold 565 00:23:47,019 --> 00:23:44,120 and remain cold for millions or billions 566 00:23:50,049 --> 00:23:47,029 of years well we are testing that idea 567 00:23:53,169 --> 00:23:50,059 with several of our investigations but 568 00:23:55,060 --> 00:23:53,179 today let me tell you that the first 569 00:23:57,190 --> 00:23:55,070 test has been with altimetry the next 570 00:24:01,990 --> 00:23:57,200 slide shows an example of one of these 571 00:24:07,230 --> 00:24:02,000 craters on one of our global mosaics the 572 00:24:09,879 --> 00:24:07,240 one in circles in red is our host a 573 00:24:13,389 --> 00:24:09,889 polar deposits on its floors you see the 574 00:24:16,419 --> 00:24:13,399 radar map superimposed on the global 575 00:24:19,090 --> 00:24:16,429 mosaic for a messenger NRL temperature 576 00:24:22,060 --> 00:24:19,100 made several passes over this particular 577 00:24:25,149 --> 00:24:22,070 crater 25 kilometers in diameter 15 578 00:24:26,560 --> 00:24:25,159 miles across early in the orbital phase 579 00:24:27,919 --> 00:24:26,570 of our mission and the next slide shows 580 00:24:30,259 --> 00:24:27,929 a contour map 581 00:24:32,359 --> 00:24:30,269 of that crater built up by the 582 00:24:36,889 --> 00:24:32,369 topographic profiles that we collected 583 00:24:39,769 --> 00:24:36,899 from orbit and this contour map combined 584 00:24:42,320 --> 00:24:39,779 with calculations of where the Sun 585 00:24:45,289 --> 00:24:42,330 shines as a function of time of year and 586 00:24:47,989 --> 00:24:45,299 position on mercury surface allows us to 587 00:24:50,029 --> 00:24:47,999 test what parts of the floor of this 588 00:24:51,739 --> 00:24:50,039 crater and other craters at high 589 00:24:54,619 --> 00:24:51,749 northern latitudes are in permanent 590 00:24:58,129 --> 00:24:54,629 shadow and indeed this crater passes the 591 00:25:01,430 --> 00:24:58,139 test the portion of the floor that is in 592 00:25:03,950 --> 00:25:01,440 permanent shadow a coincides with the 593 00:25:05,720 --> 00:25:03,960 portion of the floor of the crater where 594 00:25:10,039 --> 00:25:05,730 we see the radar bright deposits 595 00:25:12,739 --> 00:25:10,049 hypothesized to be water ice so stay 596 00:25:15,830 --> 00:25:12,749 tuned this is a very exciting hypothesis 597 00:25:18,169 --> 00:25:15,840 is now with us for 20 years that planet 598 00:25:20,600 --> 00:25:18,179 Mercury may have large quantities of 599 00:25:22,570 --> 00:25:20,610 Isis at the North and South Pole the 600 00:25:25,220 --> 00:25:22,580 very first scientific test of that 601 00:25:28,989 --> 00:25:25,230 hypothesis using messenger data from 602 00:25:31,310 --> 00:25:28,999 orbit has passed with flying colors and 603 00:25:33,019 --> 00:25:31,320 we look forward to results particularly 604 00:25:35,239 --> 00:25:33,029 from our geochemical remote-sensing 605 00:25:38,180 --> 00:25:35,249 instruments the neutron spectrometer in 606 00:25:40,369 --> 00:25:38,190 particular given enough time from orbit 607 00:25:43,879 --> 00:25:40,379 and one years we've shown is enough time 608 00:25:46,639 --> 00:25:43,889 so stay tuned we'll demonstrate whether 609 00:25:48,680 --> 00:25:46,649 or not the material at the poles is 610 00:25:51,289 --> 00:25:48,690 likely to be water ice on the basis of 611 00:25:55,789 --> 00:25:51,299 excess hydrogen let me turn now to the 612 00:25:57,649 --> 00:25:55,799 magnetic field of mercury the magnetic 613 00:25:59,570 --> 00:25:57,659 field was discovered by Mariner 10 it's 614 00:26:01,340 --> 00:25:59,580 much smaller than the magnetic field of 615 00:26:03,739 --> 00:26:01,350 the earth you probably know that Venus 616 00:26:05,779 --> 00:26:03,749 and Mars do not have a magnetic field so 617 00:26:07,519 --> 00:26:05,789 the mercury is the only other earth-like 618 00:26:10,190 --> 00:26:07,529 planet to have one and what we thought 619 00:26:12,470 --> 00:26:10,200 on the basis of the flybys was that 620 00:26:15,019 --> 00:26:12,480 mercury was a miniature version of 621 00:26:17,359 --> 00:26:15,029 Earth's magnetic field produced by 622 00:26:20,149 --> 00:26:17,369 similar processes and with broadly 623 00:26:21,710 --> 00:26:20,159 similar geometry now that we're in orbit 624 00:26:24,470 --> 00:26:21,720 we can measure that magnetic field every 625 00:26:26,649 --> 00:26:24,480 day and what we're seeing is that it is 626 00:26:29,389 --> 00:26:26,659 not a minister of the Earth's field 627 00:26:30,649 --> 00:26:29,399 before you start the animation let me 628 00:26:32,090 --> 00:26:30,659 say what you're going to see we're 629 00:26:35,359 --> 00:26:32,100 looking down on the North Pole of 630 00:26:37,999 --> 00:26:35,369 mercury every orbit we determine the 631 00:26:39,440 --> 00:26:38,009 position of the magnetic equator the 632 00:26:41,750 --> 00:26:39,450 part of the orbit where we cross 633 00:26:44,480 --> 00:26:41,760 Mercury's magnetic equator to find 634 00:26:47,060 --> 00:26:44,490 the point at which the internal magnetic 635 00:26:49,220 --> 00:26:47,070 field is parallel to the spin axis of 636 00:26:51,230 --> 00:26:49,230 the planet and those red dots of the 637 00:26:52,880 --> 00:26:51,240 location of the magnetic equator looking 638 00:26:54,110 --> 00:26:52,890 down from the North Pole so all looks 639 00:26:56,150 --> 00:26:54,120 well but now if we can start the 640 00:26:59,390 --> 00:26:56,160 animation you'll see where that magnetic 641 00:27:01,940 --> 00:26:59,400 equator loss it is not at the geographic 642 00:27:05,420 --> 00:27:01,950 equator of the planet which is that gray 643 00:27:07,730 --> 00:27:05,430 line it is north of systematically north 644 00:27:10,010 --> 00:27:07,740 on every orbit north of the geographic 645 00:27:13,130 --> 00:27:10,020 equator by two-tenths of a planet radius 646 00:27:15,470 --> 00:27:13,140 what that means is that the magnetic 647 00:27:18,200 --> 00:27:15,480 field and the northern hemisphere is 648 00:27:19,400 --> 00:27:18,210 stronger and differs from that in the 649 00:27:21,440 --> 00:27:19,410 southern hemisphere and it means that 650 00:27:23,330 --> 00:27:21,450 the process that creates the magnetic 651 00:27:25,580 --> 00:27:23,340 field which we think is somewhat similar 652 00:27:27,470 --> 00:27:25,590 to that in earth that it arises from 653 00:27:30,080 --> 00:27:27,480 Dynamo processes in the planets core 654 00:27:31,670 --> 00:27:30,090 must be capable of producing this 655 00:27:34,880 --> 00:27:31,680 asymmetry between the North and the 656 00:27:37,250 --> 00:27:34,890 South now there are some consequences of 657 00:27:38,840 --> 00:27:37,260 having this strongly asymmetric fields 658 00:27:42,440 --> 00:27:38,850 and one of them is depicted on the next 659 00:27:45,050 --> 00:27:42,450 slide if if you map the magnetic field 660 00:27:47,330 --> 00:27:45,060 lines at the north and south polar 661 00:27:51,290 --> 00:27:47,340 regions of mercury those magnetic field 662 00:27:53,870 --> 00:27:51,300 lines look pretty complicated but focus 663 00:27:55,790 --> 00:27:53,880 on what is different between the North 664 00:27:56,900 --> 00:27:55,800 and the South the north on the left and 665 00:27:59,030 --> 00:27:56,910 the south on the right and what is 666 00:28:01,880 --> 00:27:59,040 different is the area around the pole 667 00:28:05,450 --> 00:28:01,890 itself the areas were the letters n and 668 00:28:08,150 --> 00:28:05,460 s and the next slide shows those in more 669 00:28:10,550 --> 00:28:08,160 detail those areas are called polar caps 670 00:28:12,770 --> 00:28:10,560 for students of the magnetosphere and 671 00:28:16,370 --> 00:28:12,780 their areas were the field lines don't 672 00:28:18,860 --> 00:28:16,380 close around the planet but are open to 673 00:28:21,530 --> 00:28:18,870 interplanetary space why is that 674 00:28:23,540 --> 00:28:21,540 important it is important because open 675 00:28:25,670 --> 00:28:23,550 field lines are like interstate highways 676 00:28:27,740 --> 00:28:25,680 for charged particles from the inter 677 00:28:29,660 --> 00:28:27,750 planetary environment and those charged 678 00:28:31,550 --> 00:28:29,670 particles come roaring in and hit the 679 00:28:33,170 --> 00:28:31,560 surface of mercury what happens when 680 00:28:35,450 --> 00:28:33,180 they do one of the things is that 681 00:28:37,400 --> 00:28:35,460 material is kicked off the surface and 682 00:28:39,800 --> 00:28:37,410 contributes to Mercury's very tenuous 683 00:28:42,080 --> 00:28:39,810 atmosphere calls an exosphere and 684 00:28:44,180 --> 00:28:42,090 another is that the impacts of these 685 00:28:46,640 --> 00:28:44,190 charged particles changed slowly over 686 00:28:48,800 --> 00:28:46,650 time that the chemistry and the color 687 00:28:51,410 --> 00:28:48,810 and the reflective properties of the 688 00:28:53,930 --> 00:28:51,420 surface by a set of processes known as 689 00:28:55,379 --> 00:28:53,940 space weathering so a prediction of this 690 00:28:57,869 --> 00:28:55,389 new model for 691 00:28:59,819 --> 00:28:57,879 mercury's magnetic field is that the 692 00:29:03,359 --> 00:28:59,829 processes of generation of the exosphere 693 00:29:05,639 --> 00:29:03,369 and the processes of changing the color 694 00:29:07,589 --> 00:29:05,649 and reflectance of mercury service 695 00:29:09,119 --> 00:29:07,599 should be very different near the North 696 00:29:11,759 --> 00:29:09,129 Pole and near the South Pole and we'll 697 00:29:15,419 --> 00:29:11,769 be testing these ideas as we go forward 698 00:29:17,879 --> 00:29:15,429 but Mercury's magnetic field environment 699 00:29:20,190 --> 00:29:17,889 Mercury's magnetosphere is different in 700 00:29:22,319 --> 00:29:20,200 some other ways as well and I will turn 701 00:29:24,209 --> 00:29:22,329 the podium now to my colleague Ralph 702 00:29:26,819 --> 00:29:24,219 mcnutt to describe some other new 703 00:29:29,159 --> 00:29:26,829 results Thank You Sean what I'd like to 704 00:29:31,079 --> 00:29:29,169 do is to amplify on some of the things 705 00:29:33,359 --> 00:29:31,089 that Sean is talking about about the 706 00:29:35,909 --> 00:29:33,369 magnetosphere and also talk a little bit 707 00:29:38,459 --> 00:29:35,919 about rather serendipitous discovery 708 00:29:41,279 --> 00:29:38,469 that was made with the instruments that 709 00:29:43,769 --> 00:29:41,289 Larry was talking about for for doing 710 00:29:45,829 --> 00:29:43,779 our geochemistry observations and if I 711 00:29:48,839 --> 00:29:45,839 could have the first graphic please 712 00:29:50,819 --> 00:29:48,849 larry was talking about using our gamma 713 00:29:52,560 --> 00:29:50,829 ray spectrometer to look for gamma rays 714 00:29:54,180 --> 00:29:52,570 from the surface of the planet and this 715 00:29:56,129 --> 00:29:54,190 is actually what the gamma ray 716 00:29:58,409 --> 00:29:56,139 spectrometer on messenger looks like in 717 00:30:00,209 --> 00:29:58,419 schematic the yellow part at the top 718 00:30:01,919 --> 00:30:00,219 actually points back toward the surface 719 00:30:04,109 --> 00:30:01,929 of the planet that's nominally where the 720 00:30:08,369 --> 00:30:04,119 gamma rays come in through through and 721 00:30:11,699 --> 00:30:08,379 the blow-up shows the working piece of 722 00:30:13,849 --> 00:30:11,709 this the red area is actually a single 723 00:30:16,319 --> 00:30:13,859 polished crystal of germanium 724 00:30:18,239 --> 00:30:16,329 semiconductor about two and a half 725 00:30:19,859 --> 00:30:18,249 inches by two and a half inches and 726 00:30:22,349 --> 00:30:19,869 that's what we use for actually looking 727 00:30:25,619 --> 00:30:22,359 at the looking at the gamma rays but it 728 00:30:27,690 --> 00:30:25,629 turns out that at energies that are 729 00:30:29,190 --> 00:30:27,700 lower than what we use for looking at 730 00:30:31,589 --> 00:30:29,200 the gamma rays there is still some 731 00:30:35,099 --> 00:30:31,599 response of the instrument to what is 732 00:30:37,289 --> 00:30:35,109 also going or going on nearby to the 733 00:30:40,649 --> 00:30:37,299 spacecraft and if I could have the next 734 00:30:43,019 --> 00:30:40,659 graphic please round the spacecraft in 735 00:30:46,680 --> 00:30:43,029 the magnetosphere we know that there are 736 00:30:48,209 --> 00:30:46,690 charged particles the plasma one of the 737 00:30:50,849 --> 00:30:48,219 things that of course has been a big 738 00:30:53,509 --> 00:30:50,859 mystery is that at the time of the 739 00:30:56,940 --> 00:30:53,519 mariner 10 fly by the first one back in 740 00:30:58,469 --> 00:30:56,950 1974 not only was the magnetic field of 741 00:31:00,119 --> 00:30:58,479 the magnetosphere discovered but there 742 00:31:03,659 --> 00:31:00,129 were also these bursts of energetic 743 00:31:05,940 --> 00:31:03,669 electrons and this is something that we 744 00:31:07,889 --> 00:31:05,950 haven't seen on any of the flybys that 745 00:31:09,180 --> 00:31:07,899 we've had with messenger going by going 746 00:31:11,730 --> 00:31:09,190 by the planet and we've 747 00:31:13,560 --> 00:31:11,740 have we have a detector that's on board 748 00:31:15,660 --> 00:31:13,570 the energetic particle spectrometer 749 00:31:18,480 --> 00:31:15,670 specifically for looking for events like 750 00:31:22,170 --> 00:31:18,490 that and it's been quite silent during 751 00:31:24,330 --> 00:31:22,180 all the flybys we we had but then 752 00:31:26,400 --> 00:31:24,340 something interesting happened once that 753 00:31:28,200 --> 00:31:26,410 we finally got into orbit and this just 754 00:31:30,390 --> 00:31:28,210 illustrates one of the things that can 755 00:31:32,040 --> 00:31:30,400 happen in particular with the gamma ray 756 00:31:34,740 --> 00:31:32,050 spectrometers it's got a very large 757 00:31:37,080 --> 00:31:34,750 active area that allows you to see 758 00:31:39,150 --> 00:31:37,090 things that you can't necessarily see 759 00:31:41,580 --> 00:31:39,160 with the other instruments we of course 760 00:31:44,100 --> 00:31:41,590 got there's a possibility of having 761 00:31:45,810 --> 00:31:44,110 electrons near the near the spacecraft 762 00:31:47,820 --> 00:31:45,820 those are indicated on the left and 763 00:31:50,520 --> 00:31:47,830 those can come in and actually hit the 764 00:31:52,800 --> 00:31:50,530 outer case of the instrument if I could 765 00:31:54,870 --> 00:31:52,810 go to the next graphic they're not 766 00:31:56,940 --> 00:31:54,880 energetic enough necessarily to go 767 00:31:59,910 --> 00:31:56,950 through that case but what does happen 768 00:32:02,490 --> 00:31:59,920 and what can happen is I can actually 769 00:32:04,470 --> 00:32:02,500 make x-rays internal to the instrument 770 00:32:07,410 --> 00:32:04,480 itself and it's exactly the same 771 00:32:10,050 --> 00:32:07,420 physical process that's used in medical 772 00:32:12,690 --> 00:32:10,060 x-ray imaging equipment it's exactly the 773 00:32:14,400 --> 00:32:12,700 same process that happens in the upper 774 00:32:17,790 --> 00:32:14,410 atmosphere of the corona of the Sun 775 00:32:20,580 --> 00:32:17,800 where that hard x-ray fluxes are 776 00:32:22,950 --> 00:32:20,590 emanated from such as have happened here 777 00:32:24,810 --> 00:32:22,960 in the last couple of weeks and so one 778 00:32:26,640 --> 00:32:24,820 of the possibilities we actually have 779 00:32:28,500 --> 00:32:26,650 with this instrument is not only in 780 00:32:31,410 --> 00:32:28,510 looking at the gamma rays coming back 781 00:32:34,140 --> 00:32:31,420 from the surface but actually being able 782 00:32:35,850 --> 00:32:34,150 to see gamma rays that are being that 783 00:32:39,090 --> 00:32:35,860 are being produced within the instrument 784 00:32:41,910 --> 00:32:39,100 housing itself if there are enough 785 00:32:44,220 --> 00:32:41,920 electrons in the region of space that 786 00:32:46,140 --> 00:32:44,230 we're flying through certainly the kind 787 00:32:48,810 --> 00:32:46,150 of usage of this instrument that it was 788 00:32:50,970 --> 00:32:48,820 not designed for but again it gets back 789 00:32:52,890 --> 00:32:50,980 to serendipity having a having a happy 790 00:32:55,380 --> 00:32:52,900 discovery based upon something one 791 00:32:58,110 --> 00:32:55,390 wasn't expecting if I could go to the 792 00:32:59,550 --> 00:32:58,120 next graphic please and let me just let 793 00:33:01,590 --> 00:32:59,560 me just explain this for a minute this 794 00:33:04,260 --> 00:33:01,600 is very similar to what Sean was just 795 00:33:07,560 --> 00:33:04,270 showing you with the wear that the the 796 00:33:10,050 --> 00:33:07,570 magnetic equator lines up on the planet 797 00:33:11,960 --> 00:33:10,060 in this case again we're looking down on 798 00:33:14,430 --> 00:33:11,970 mercury from the top from the North Pole 799 00:33:16,920 --> 00:33:14,440 but in this case what we're looking at 800 00:33:20,190 --> 00:33:16,930 the the greens and the arrow regions are 801 00:33:22,010 --> 00:33:20,200 the pieces of the orbits that are the 802 00:33:24,440 --> 00:33:22,020 basically we've painted 803 00:33:27,560 --> 00:33:24,450 with the areas where we've seen these 804 00:33:29,540 --> 00:33:27,570 energetic electrons and it's not a 805 00:33:31,490 --> 00:33:29,550 question of just simply flying through 806 00:33:34,580 --> 00:33:31,500 the area and having the electron flux 807 00:33:36,710 --> 00:33:34,590 come up we see this as burst sometimes 808 00:33:38,870 --> 00:33:36,720 they're only there are only tens of 809 00:33:42,080 --> 00:33:38,880 seconds long sometimes they last for 810 00:33:44,630 --> 00:33:42,090 several minutes they're sporadic but 811 00:33:47,000 --> 00:33:44,640 they happen like clockwork almost on 812 00:33:48,320 --> 00:33:47,010 every orbit a lot of variations and the 813 00:33:50,330 --> 00:33:48,330 other thing it's important to notice 814 00:33:52,160 --> 00:33:50,340 note from this graphic as I look down on 815 00:33:56,360 --> 00:33:52,170 this this is Anna coordinate system 816 00:34:00,170 --> 00:33:56,370 where that the Sun is off to thee is off 817 00:34:02,900 --> 00:34:00,180 on the the the right hand side and where 818 00:34:04,640 --> 00:34:02,910 we're seeing these are located all 819 00:34:08,000 --> 00:34:04,650 around the planet and if we could go 820 00:34:09,740 --> 00:34:08,010 ahead and roll this as a film clip this 821 00:34:11,630 --> 00:34:09,750 shows why that we didn't see them bring 822 00:34:14,060 --> 00:34:11,640 the flybys they're all in the northern 823 00:34:16,730 --> 00:34:14,070 hemisphere sort of the darkish gray 824 00:34:19,159 --> 00:34:16,740 areas or the lightest grey areas on here 825 00:34:21,350 --> 00:34:19,169 are pieces of the orbits that the 826 00:34:22,639 --> 00:34:21,360 messenger was in as has been in since 827 00:34:25,340 --> 00:34:22,649 we've gotten into orbit around the 828 00:34:27,320 --> 00:34:25,350 planet and you can see the distribution 829 00:34:30,380 --> 00:34:27,330 of these things tends to be at mid 830 00:34:32,480 --> 00:34:30,390 northern latitudes the blue ones which 831 00:34:34,700 --> 00:34:32,490 tend to be more symmetric about the 832 00:34:37,280 --> 00:34:34,710 planet or at higher energies from the 833 00:34:38,810 --> 00:34:37,290 from the the gamma ray detector the 834 00:34:41,240 --> 00:34:38,820 lower energy ones are from similar 835 00:34:43,010 --> 00:34:41,250 physical processes that we're seeing in 836 00:34:44,990 --> 00:34:43,020 the x-ray detector again that's the same 837 00:34:47,720 --> 00:34:45,000 two instruments that Larry was talking 838 00:34:50,360 --> 00:34:47,730 about in a region of the measurement 839 00:34:51,830 --> 00:34:50,370 Shane where that there's no interference 840 00:34:54,260 --> 00:34:51,840 with what we're looking for with the 841 00:34:56,600 --> 00:34:54,270 geochemistry and nonetheless that we're 842 00:34:59,120 --> 00:34:56,610 able to get an idea of what's going on 843 00:35:00,620 --> 00:34:59,130 around the planet and it turns out of 844 00:35:02,750 --> 00:35:00,630 course that with the three messenger 845 00:35:05,030 --> 00:35:02,760 flybys those were all near the 846 00:35:07,940 --> 00:35:05,040 equatorial plane where we don't see any 847 00:35:11,450 --> 00:35:07,950 of these events the mariner 10 flyby 848 00:35:13,940 --> 00:35:11,460 back in 1974 was at high northern 849 00:35:16,430 --> 00:35:13,950 latitudes and again these events for all 850 00:35:18,320 --> 00:35:16,440 the world look exactly like what was 851 00:35:19,910 --> 00:35:18,330 seen on Mariner 10 so the reason we 852 00:35:22,040 --> 00:35:19,920 didn't see them on messenger is simply 853 00:35:24,650 --> 00:35:22,050 because we were going through the wrong 854 00:35:27,230 --> 00:35:24,660 part of the planets magnetosphere and if 855 00:35:28,820 --> 00:35:27,240 I could go to the last graphic this is 856 00:35:31,880 --> 00:35:28,830 an attempt to sort of put all of this in 857 00:35:33,800 --> 00:35:31,890 context again the Sun is sitting off on 858 00:35:35,930 --> 00:35:33,810 the off on the right-hand side and this 859 00:35:37,880 --> 00:35:35,940 is a schematic that's showing 860 00:35:40,910 --> 00:35:37,890 selection of some of the magnetic field 861 00:35:42,440 --> 00:35:40,920 lines the solar wind blows outward from 862 00:35:44,690 --> 00:35:42,450 the Sun intends to compress the 863 00:35:46,390 --> 00:35:44,700 magnetosphere on on the sunward side of 864 00:35:48,650 --> 00:35:46,400 the planet and there's a so-called 865 00:35:50,900 --> 00:35:48,660 magnetotail where the field lines are 866 00:35:52,460 --> 00:35:50,910 drawn out on the other side you can see 867 00:35:54,760 --> 00:35:52,470 the magnetic equator here in this 868 00:35:57,470 --> 00:35:54,770 schematic we've displaced it northward 869 00:35:59,089 --> 00:35:57,480 again this gets back to what Sean was 870 00:36:00,500 --> 00:35:59,099 illustrating about the difference in 871 00:36:03,740 --> 00:36:00,510 this magnetic field from that of the 872 00:36:06,109 --> 00:36:03,750 earth and and the again the green areas 873 00:36:08,300 --> 00:36:06,119 are where we've seen the x-ray where the 874 00:36:11,599 --> 00:36:08,310 x-ray detector has lit up with lower 875 00:36:13,490 --> 00:36:11,609 energy emissions from electrons that 876 00:36:15,970 --> 00:36:13,500 have characteristic energies of maybe 877 00:36:18,770 --> 00:36:15,980 five to ten kilo electron volts and the 878 00:36:21,280 --> 00:36:18,780 blue regions are aware that the the 879 00:36:24,170 --> 00:36:21,290 gamma ray spectrometer has lit up with 880 00:36:26,390 --> 00:36:24,180 electrons due to electrons that are that 881 00:36:29,569 --> 00:36:26,400 are at higher energies one of the 882 00:36:31,280 --> 00:36:29,579 original ideas was that if indeed there 883 00:36:34,099 --> 00:36:31,290 were energetic particles that they would 884 00:36:36,740 --> 00:36:34,109 tend to be concentrated in the night 885 00:36:38,359 --> 00:36:36,750 side of the planets magnetosphere but 886 00:36:39,950 --> 00:36:38,369 that's not what we're seeing we really 887 00:36:43,010 --> 00:36:39,960 are seeing them all around the planet 888 00:36:45,079 --> 00:36:43,020 and this is really different again from 889 00:36:46,250 --> 00:36:45,089 the sorts of things that we've typically 890 00:36:48,800 --> 00:36:46,260 seen in the earth and the Earth's 891 00:36:51,950 --> 00:36:48,810 magnetosphere there was a lot of of work 892 00:36:55,190 --> 00:36:51,960 back after them the mariner 10 flybys 893 00:36:56,809 --> 00:36:55,200 speculation on how that mercury and the 894 00:36:59,510 --> 00:36:56,819 Earth's magnetosphere might be similar 895 00:37:01,309 --> 00:36:59,520 but once again as with some of these 896 00:37:03,140 --> 00:37:01,319 other observations such as with the 897 00:37:06,079 --> 00:37:03,150 geochemistry the planet we're finding 898 00:37:09,819 --> 00:37:06,089 out that mercury really is a world in 899 00:37:12,260 --> 00:37:09,829 and of its own and we're finding that 900 00:37:15,140 --> 00:37:12,270 just like the earth it's got its own 901 00:37:17,569 --> 00:37:15,150 personality mercury is one of the 902 00:37:20,120 --> 00:37:17,579 terrestrial planets and therefore 903 00:37:21,829 --> 00:37:20,130 provide some context for what was going 904 00:37:24,079 --> 00:37:21,839 on in the inner part of the solar system 905 00:37:26,690 --> 00:37:24,089 back when that the planets were 906 00:37:29,210 --> 00:37:26,700 condensing from the solar nebula but as 907 00:37:31,220 --> 00:37:29,220 we look and as we continue to look with 908 00:37:33,920 --> 00:37:31,230 messenger at mercury looking close up 909 00:37:36,050 --> 00:37:33,930 with targeted observations using all of 910 00:37:37,280 --> 00:37:36,060 the various instrumentation such as 911 00:37:39,800 --> 00:37:37,290 things that were simply not available 912 00:37:43,040 --> 00:37:39,810 with the technology at the time of 913 00:37:46,069 --> 00:37:43,050 Mariner 10 we're managing to really 914 00:37:49,040 --> 00:37:46,079 explore a new world for the first time 915 00:37:49,550 --> 00:37:49,050 we are out there on the edge we're doing 916 00:37:51,500 --> 00:37:49,560 things 917 00:37:53,960 --> 00:37:51,510 with technology that had to be developed 918 00:37:57,560 --> 00:37:53,970 for this mission and we're learning 919 00:38:01,630 --> 00:37:57,570 things by being in a place that no human 920 00:38:05,090 --> 00:38:01,640 being has ever by proxy gone before and 921 00:38:07,130 --> 00:38:05,100 that's what science and exploration and 922 00:38:08,750 --> 00:38:07,140 the sorts of things that come out of the 923 00:38:11,690 --> 00:38:08,760 science Mission Directorate at NASA are 924 00:38:16,940 --> 00:38:11,700 all about and I think all of us are very 925 00:38:19,820 --> 00:38:16,950 pleased to be part of messenger as one 926 00:38:22,340 --> 00:38:19,830 of these discovery missions which has 927 00:38:25,250 --> 00:38:22,350 now gone through only one quarter of its 928 00:38:27,650 --> 00:38:25,260 nominal mission at mercury and there's a 929 00:38:30,200 --> 00:38:27,660 lot more to come and all I can say is 930 00:38:33,920 --> 00:38:30,210 keep following us the best is yet to be 931 00:38:36,560 --> 00:38:33,930 and Wayne thank you all congratulations 932 00:38:37,970 --> 00:38:36,570 again just a reminder to our television 933 00:38:39,860 --> 00:38:37,980 audience all the images that were 934 00:38:44,690 --> 00:38:39,870 presented today and much much more is on 935 00:38:47,540 --> 00:38:44,700 www yoga / messenger now I kind of snuck 936 00:38:49,310 --> 00:38:47,550 in in my introductory remarks a little 937 00:38:50,630 --> 00:38:49,320 surprise of our own here you heard about 938 00:38:52,850 --> 00:38:50,640 the surprises of mercury but 939 00:38:54,470 --> 00:38:52,860 headquarters has a surprise so before we 940 00:38:57,950 --> 00:38:54,480 open it up for questions I would like 941 00:38:59,840 --> 00:38:57,960 dr. Jim Green the director of NASA's 942 00:39:09,170 --> 00:38:59,850 planetary science division to come to 943 00:39:13,850 --> 00:39:09,180 the stage thank you doing in Shawn will 944 00:39:17,480 --> 00:39:13,860 you please come here thank you on behalf 945 00:39:20,360 --> 00:39:17,490 of NASA and the US Postal Service is my 946 00:39:22,520 --> 00:39:20,370 great pleasure to give you a commitment 947 00:39:24,890 --> 00:39:22,530 of commemorative first day cover it's 948 00:39:27,980 --> 00:39:24,900 everything mercury that NASA is doing 949 00:39:29,210 --> 00:39:27,990 for 50 years for 50 years and as you 950 00:39:31,160 --> 00:39:29,220 know with the stamps that have been 951 00:39:33,260 --> 00:39:31,170 issued its forever they're forever 952 00:39:35,750 --> 00:39:33,270 stamps is forever mercury and Israel 953 00:39:37,970 --> 00:39:35,760 said more great Sciences you have to be 954 00:39:39,770 --> 00:39:37,980 coming with with the rest of the mission 955 00:39:42,050 --> 00:39:39,780 so congratulations to you and the team 956 00:39:44,090 --> 00:39:42,060 occasion like the first that you have 957 00:39:52,569 --> 00:39:44,100 and getting messenger in orbit all right 958 00:39:57,469 --> 00:39:56,329 okay let's see if we have any questions 959 00:39:59,539 --> 00:39:57,479 here we're going to start here now so 960 00:40:04,370 --> 00:39:59,549 headquarters wait for the mic give you a 961 00:40:06,019 --> 00:40:04,380 name and affiliation Randy Shostak 962 00:40:08,420 --> 00:40:06,029 reported with eos newspaper of the 963 00:40:10,009 --> 00:40:08,430 American Geophysical Union this is very 964 00:40:12,979 --> 00:40:10,019 exciting information thank you for the 965 00:40:15,380 --> 00:40:12,989 press conference um I wondered if you 966 00:40:17,509 --> 00:40:15,390 could elaborate particularly on some of 967 00:40:20,359 --> 00:40:17,519 the latter comments by dr. McNutt and if 968 00:40:23,959 --> 00:40:20,369 you can put this in broader context in 969 00:40:25,969 --> 00:40:23,969 for me what does all this add up to what 970 00:40:28,579 --> 00:40:25,979 do all these new images what do all 971 00:40:30,529 --> 00:40:28,589 these new findings add up to and at this 972 00:40:33,529 --> 00:40:30,539 point what are you most pleased about to 973 00:40:35,709 --> 00:40:33,539 date and what what are the the surprises 974 00:40:38,089 --> 00:40:35,719 and and things that puzzle you the most 975 00:40:39,739 --> 00:40:38,099 well I think that certainly the thing 976 00:40:41,269 --> 00:40:39,749 that we're most pleased about is that 977 00:40:43,069 --> 00:40:41,279 we're in orbit we've got a healthy 978 00:40:44,719 --> 00:40:43,079 spacecraft we've gotten through the 979 00:40:47,479 --> 00:40:44,729 hottest part of the orbit and everything 980 00:40:49,609 --> 00:40:47,489 is still working you know I've 981 00:40:52,339 --> 00:40:49,619 personally been involved in a variety of 982 00:40:55,370 --> 00:40:52,349 NASA missions and all I can say is that 983 00:40:58,969 --> 00:40:55,380 I keep being amazed every morning that I 984 00:41:01,539 --> 00:40:58,979 get up how well that messenger is going 985 00:41:04,670 --> 00:41:01,549 it has been it has been a tremendous 986 00:41:07,609 --> 00:41:04,680 partnership between the messenger team 987 00:41:09,829 --> 00:41:07,619 and NASA actually again pulling 988 00:41:13,099 --> 00:41:09,839 something off that no one has ever done 989 00:41:15,349 --> 00:41:13,109 before I think in terms of what we're 990 00:41:17,509 --> 00:41:15,359 learning again one of the things that we 991 00:41:21,259 --> 00:41:17,519 said when we started the mission in the 992 00:41:23,719 --> 00:41:21,269 beginning is that mercury is that end 993 00:41:25,789 --> 00:41:23,729 member planet of the terrestrial planets 994 00:41:28,670 --> 00:41:25,799 it tells us something about the inner 995 00:41:30,709 --> 00:41:28,680 part of the solar nebula it tells us 996 00:41:32,959 --> 00:41:30,719 something about how the terrestrial 997 00:41:35,150 --> 00:41:32,969 planets formed ultimately again the 998 00:41:37,430 --> 00:41:35,160 sorts of results that that Larry was 999 00:41:40,189 --> 00:41:37,440 discussing about how that the potassium 1000 00:41:42,349 --> 00:41:40,199 thorium ratio differs amongst the 1001 00:41:45,199 --> 00:41:42,359 planets and that and that mercury has 1002 00:41:47,209 --> 00:41:45,209 really been a surprise there it's 1003 00:41:49,969 --> 00:41:47,219 certainly clear from that as well as 1004 00:41:52,140 --> 00:41:49,979 from the images that the rut was showing 1005 00:41:54,960 --> 00:41:52,150 is that 1006 00:41:58,019 --> 00:41:54,970 comments to the contrary mercury ain't 1007 00:42:00,420 --> 00:41:58,029 the moon there have been a lot of a lot 1008 00:42:02,039 --> 00:42:00,430 of comments that one would read saying 1009 00:42:04,529 --> 00:42:02,049 how that well it just looks like another 1010 00:42:06,630 --> 00:42:04,539 dead piece of rock like the moon why are 1011 00:42:10,799 --> 00:42:06,640 we doing this and the reason we're doing 1012 00:42:12,690 --> 00:42:10,809 it is because I you learn something by 1013 00:42:15,319 --> 00:42:12,700 going to places that we haven't been 1014 00:42:19,380 --> 00:42:15,329 before in the solar system is our home 1015 00:42:21,120 --> 00:42:19,390 we're here we know that we don't know we 1016 00:42:23,339 --> 00:42:21,130 don't know as much as me we might like 1017 00:42:26,519 --> 00:42:23,349 to about our origins and about kind of 1018 00:42:29,430 --> 00:42:26,529 where how all of this came together and 1019 00:42:31,920 --> 00:42:29,440 by going back and taking a look in 1020 00:42:34,680 --> 00:42:31,930 detail at places like mercury we're able 1021 00:42:37,200 --> 00:42:34,690 to put more of those jigsaw puzzle 1022 00:42:39,960 --> 00:42:37,210 pieces together again sean is talking 1023 00:42:42,000 --> 00:42:39,970 about the fact that we've got this this 1024 00:42:45,420 --> 00:42:42,010 very interesting magnetic field 1025 00:42:46,890 --> 00:42:45,430 configuration the only other place in 1026 00:42:49,529 --> 00:42:46,900 the solar system where that you have 1027 00:42:51,990 --> 00:42:49,539 something like this is the magnetic 1028 00:42:54,150 --> 00:42:52,000 field of Saturn where that the spin axis 1029 00:42:56,910 --> 00:42:54,160 and the dipole axis are aligned and it 1030 00:42:58,980 --> 00:42:56,920 turns out that the magnetic equator of 1031 00:43:02,010 --> 00:42:58,990 Saturn is displaced northward of its 1032 00:43:03,450 --> 00:43:02,020 geographic equator not by as larger 1033 00:43:06,480 --> 00:43:03,460 percentage something like about I think 1034 00:43:08,809 --> 00:43:06,490 six I think it's like point 06 Saturn 1035 00:43:12,180 --> 00:43:08,819 radii is compared to about point to 1036 00:43:15,269 --> 00:43:12,190 mercury radii for mercury and certainly 1037 00:43:18,180 --> 00:43:15,279 the the environment and the chemistry 1038 00:43:21,000 --> 00:43:18,190 and the and the geophysics of mercury 1039 00:43:25,019 --> 00:43:21,010 and and Saturn are quite different and 1040 00:43:27,980 --> 00:43:25,029 yet now we have examples of two active 1041 00:43:31,890 --> 00:43:27,990 planetary dynamos in the solar system 1042 00:43:34,349 --> 00:43:31,900 that shouldn't be there and for a long 1043 00:43:37,260 --> 00:43:34,359 time I know with with the investigators 1044 00:43:40,200 --> 00:43:37,270 that first void for well first really at 1045 00:43:42,630 --> 00:43:40,210 pioneer 11 and then with Voyager and now 1046 00:43:44,760 --> 00:43:42,640 of course with Cassini there's been a 1047 00:43:46,890 --> 00:43:44,770 lot of speculation about whether that 1048 00:43:49,319 --> 00:43:46,900 Saturn was just sort of the odd man out 1049 00:43:50,970 --> 00:43:49,329 well now with these messenger 1050 00:43:53,160 --> 00:43:50,980 observations we've been able to show 1051 00:43:56,339 --> 00:43:53,170 that now it's just it's just an example 1052 00:43:58,019 --> 00:43:56,349 it's one of two I think that I think 1053 00:43:59,789 --> 00:43:58,029 that one of the other really surprising 1054 00:44:03,259 --> 00:43:59,799 things and very interesting things is 1055 00:44:07,699 --> 00:44:03,269 again this this example of how much 1056 00:44:09,919 --> 00:44:07,709 flooded area of pyroclastic flows these 1057 00:44:11,569 --> 00:44:09,929 explosive flows of volcanism early in 1058 00:44:13,519 --> 00:44:11,579 the history the planet there are and of 1059 00:44:16,009 --> 00:44:13,529 course one of the things we've remarked 1060 00:44:18,589 --> 00:44:16,019 upon before or the or the so-called 1061 00:44:22,249 --> 00:44:18,599 lobate scarps where that we see this 1062 00:44:25,159 --> 00:44:22,259 evidence of mercury having shrunk with 1063 00:44:26,959 --> 00:44:25,169 the the crust folding over where of 1064 00:44:30,319 --> 00:44:26,969 course Shawn's been talking about the 1065 00:44:32,839 --> 00:44:30,329 the idea about the the ice and the 1066 00:44:35,929 --> 00:44:32,849 craters and the fact that we have this 1067 00:44:37,849 --> 00:44:35,939 lidar this laser altimeter that's now in 1068 00:44:40,069 --> 00:44:37,859 orbit around mercury where that we can 1069 00:44:42,380 --> 00:44:40,079 make these deductions about the overall 1070 00:44:44,329 --> 00:44:42,390 topography of the planet I mean this is 1071 00:44:47,509 --> 00:44:44,339 just incredible there's again there is 1072 00:44:49,519 --> 00:44:47,519 oh there's a lot more to come so I don't 1073 00:44:52,219 --> 00:44:49,529 think it's so much a question of what is 1074 00:44:54,620 --> 00:44:52,229 the most amazing but really the question 1075 00:44:56,599 --> 00:44:54,630 of what about the mission and the 1076 00:44:59,029 --> 00:44:56,609 results to date have not been amazing 1077 00:45:01,339 --> 00:44:59,039 because this really is the undiscovered 1078 00:45:04,729 --> 00:45:01,349 country and we really are for the first 1079 00:45:06,620 --> 00:45:04,739 time exploring a new world you have a 1080 00:45:08,449 --> 00:45:06,630 question you pass the mic and there a 1081 00:45:10,759 --> 00:45:08,459 name and affiliation please haiyan 1082 00:45:12,079 --> 00:45:10,769 walters with the German press agency um 1083 00:45:13,729 --> 00:45:12,089 you mentioned quite a number of 1084 00:45:16,039 --> 00:45:13,739 observations that you've had that 1085 00:45:17,959 --> 00:45:16,049 weren't what you were expecting to see 1086 00:45:20,539 --> 00:45:17,969 and I was hoping that you could maybe 1087 00:45:23,659 --> 00:45:20,549 say what was the biggest misconception 1088 00:45:27,729 --> 00:45:23,669 that there was about mercury before you 1089 00:45:32,809 --> 00:45:27,739 started this mission the biggest 1090 00:45:35,389 --> 00:45:32,819 misconception the biggest misconception 1091 00:45:37,899 --> 00:45:35,399 was that we would go to a planet orbited 1092 00:45:43,969 --> 00:45:37,909 for the first time and not be surprised 1093 00:45:48,129 --> 00:45:43,979 and and some even in the planetary 1094 00:45:52,549 --> 00:45:48,139 community after the mariner 10 mission 1095 00:45:55,659 --> 00:45:52,559 placed a low priority on returning a 1096 00:45:59,449 --> 00:45:55,669 spacecraft to mercury on the grounds 1097 00:46:01,639 --> 00:45:59,459 that it was very much like the moon we 1098 00:46:04,519 --> 00:46:01,649 had been to the moon it was an example 1099 00:46:07,039 --> 00:46:04,529 to use a phrase coined by a very famous 1100 00:46:12,139 --> 00:46:07,049 space scientist one of the burnt-out 1101 00:46:15,769 --> 00:46:12,149 cinders of the solar system and it is 1102 00:46:16,819 --> 00:46:15,779 anything but that just to elaborate very 1103 00:46:20,029 --> 00:46:16,829 brief them on the 1104 00:46:22,969 --> 00:46:20,039 summary that Ralph gave and give a 1105 00:46:24,910 --> 00:46:22,979 little more context NASA is doing some 1106 00:46:28,609 --> 00:46:24,920 other wonderful missions that are 1107 00:46:30,680 --> 00:46:28,619 expanding at a huge rate our knowledge 1108 00:46:33,440 --> 00:46:30,690 of planets around other stars you know 1109 00:46:36,229 --> 00:46:33,450 Kepler's announced tripled the number of 1110 00:46:37,699 --> 00:46:36,239 extrasolar planets recently in their 1111 00:46:41,569 --> 00:46:37,709 announcements and and many of those 1112 00:46:44,719 --> 00:46:41,579 planets are at distances similar to that 1113 00:46:47,779 --> 00:46:44,729 of mercury from our Sun many are of a 1114 00:46:51,829 --> 00:46:47,789 growing number are of masses that are 1115 00:46:53,809 --> 00:46:51,839 approaching that of Earth and Venus but 1116 00:46:57,579 --> 00:46:53,819 we have in our solar system for 1117 00:47:00,499 --> 00:46:57,589 experiments in how earth-like planets 1118 00:47:02,839 --> 00:47:00,509 evolved once they form under slightly 1119 00:47:05,469 --> 00:47:02,849 different conditions different distance 1120 00:47:09,859 --> 00:47:05,479 from the host star a different mass 1121 00:47:11,359 --> 00:47:09,869 different starting composition what 1122 00:47:13,009 --> 00:47:11,369 we're learning is that each of those 1123 00:47:16,009 --> 00:47:13,019 experiments had an extraordinarily 1124 00:47:19,219 --> 00:47:16,019 different outcome and one of those 1125 00:47:21,499 --> 00:47:19,229 experiments we live on so it really 1126 00:47:24,859 --> 00:47:21,509 behooves us to understand in a very 1127 00:47:29,180 --> 00:47:24,869 general way how earth-like planets form 1128 00:47:32,890 --> 00:47:29,190 and evolve and operate and what mercury 1129 00:47:37,279 --> 00:47:32,900 is telling us is we didn't understand 1130 00:47:41,620 --> 00:47:37,289 incomplete generality how planets of the 1131 00:47:45,650 --> 00:47:41,630 earth like class operate in detail so 1132 00:47:48,589 --> 00:47:45,660 we're learning new things every day okay 1133 00:47:50,539 --> 00:47:48,599 now we will switch over and go down to 1134 00:47:57,319 --> 00:47:50,549 the Kennedy Space Center where I believe 1135 00:47:59,599 --> 00:47:57,329 we have a question Kennedy hello ken 1136 00:48:02,539 --> 00:47:59,609 kremer from space flight magazine for 1137 00:48:04,519 --> 00:48:02,549 anybody please you talked about the the 1138 00:48:06,739 --> 00:48:04,529 water ice at the North Pole I'm 1139 00:48:09,259 --> 00:48:06,749 wondering about how much of the surface 1140 00:48:12,109 --> 00:48:09,269 do you think would would be covered with 1141 00:48:13,969 --> 00:48:12,119 this water ice is the fact that it was 1142 00:48:15,289 --> 00:48:13,979 depressed about nine kilometers I think 1143 00:48:17,900 --> 00:48:15,299 you mentioned does that increase or 1144 00:48:21,559 --> 00:48:17,910 decrease the chances of finding water 1145 00:48:23,089 --> 00:48:21,569 ricin is the LRO data with a similar 1146 00:48:24,709 --> 00:48:23,099 instrument are you comparing results 1147 00:48:27,650 --> 00:48:24,719 there and has that been helpful in 1148 00:48:28,910 --> 00:48:27,660 interpreting your data at all thanks Ken 1149 00:48:30,730 --> 00:48:28,920 let me take that question this is sean 1150 00:48:37,250 --> 00:48:30,740 solomon 1151 00:48:39,050 --> 00:48:37,260 in parts the the area of a polar 1152 00:48:41,720 --> 00:48:39,060 deposits has been well worked out by the 1153 00:48:44,060 --> 00:48:41,730 earth base braids are folks that area is 1154 00:48:45,470 --> 00:48:44,070 quite a bit larger than on the moon we 1155 00:48:46,900 --> 00:48:45,480 don't know the thickness of those 1156 00:48:50,870 --> 00:48:46,910 deposits we know that it's thick enough 1157 00:48:52,700 --> 00:48:50,880 to to have radar bright characteristics 1158 00:48:54,500 --> 00:48:52,710 for radar of different wavelengths which 1159 00:48:57,440 --> 00:48:54,510 means it's at least several red or 1160 00:49:02,150 --> 00:48:57,450 thicknesses in extent and the vertical 1161 00:49:05,090 --> 00:49:02,160 direction meaning meters or more there 1162 00:49:06,860 --> 00:49:05,100 isn't a beautiful laser altimeter on the 1163 00:49:09,710 --> 00:49:06,870 Lunar Reconnaissance Orbiter known as 1164 00:49:13,280 --> 00:49:09,720 Lola and that is producing data at a 1165 00:49:16,400 --> 00:49:13,290 huge rate and the topographic maps that 1166 00:49:19,490 --> 00:49:16,410 the lunar reconnaissance orbiter is is 1167 00:49:22,040 --> 00:49:19,500 send is creating from the Lola data is 1168 00:49:25,730 --> 00:49:22,050 just exquisite in its detail and is 1169 00:49:28,220 --> 00:49:25,740 indeed helping to define as our images 1170 00:49:30,950 --> 00:49:28,230 taken from the same spacecraft areas of 1171 00:49:32,360 --> 00:49:30,960 permanent shadow and as you know nASA 1172 00:49:35,540 --> 00:49:32,370 has flown other missions like the L 1173 00:49:37,640 --> 00:49:35,550 crossed mission that impacted into one 1174 00:49:39,410 --> 00:49:37,650 of the south polar craters thought to 1175 00:49:41,750 --> 00:49:39,420 have water and other volatile and showed 1176 00:49:43,760 --> 00:49:41,760 quite spectacularly in on the basis of 1177 00:49:46,970 --> 00:49:43,770 spectral evidence from the ejecta that 1178 00:49:49,460 --> 00:49:46,980 that there is water there but if water 1179 00:49:51,470 --> 00:49:49,470 is the major constituent of the polar 1180 00:49:53,710 --> 00:49:51,480 deposits on mercury then we have the 1181 00:49:57,470 --> 00:49:53,720 irony that the planet closest to the Sun 1182 00:50:00,430 --> 00:49:57,480 is going to have more ice at its poles 1183 00:50:03,320 --> 00:50:00,440 than even our own moon and so stay tuned 1184 00:50:04,910 --> 00:50:03,330 as this mission evolves will be relying 1185 00:50:06,470 --> 00:50:04,920 more and more on the geochemical 1186 00:50:08,690 --> 00:50:06,480 remote-sensing instruments which take 1187 00:50:10,370 --> 00:50:08,700 time to build up their observations but 1188 00:50:13,370 --> 00:50:10,380 the neutron spectrometer the gamma ray 1189 00:50:15,350 --> 00:50:13,380 spectrometer have the ability to tell us 1190 00:50:17,780 --> 00:50:15,360 what those materials are is it water 1191 00:50:19,790 --> 00:50:17,790 rises it's something else and we expect 1192 00:50:25,550 --> 00:50:19,800 to have that answer before our mission 1193 00:50:28,580 --> 00:50:25,560 is done ok now we can go to the phone 1194 00:50:36,250 --> 00:50:28,590 line and will take first Lisa Grossman 1195 00:50:41,570 --> 00:50:39,380 and that's the data from spectrometers 1196 00:50:43,430 --> 00:50:41,580 is ruling out some models of what 1197 00:50:46,420 --> 00:50:43,440 Mercury's composition can be what models 1198 00:50:48,980 --> 00:50:46,430 are those and what ones are left over 1199 00:50:54,100 --> 00:50:48,990 well so repeat that Lisa could you 1200 00:51:00,950 --> 00:50:58,970 sorry sorry about that um I was 1201 00:51:02,900 --> 00:51:00,960 wondering what the models of Mercury's 1202 00:51:05,990 --> 00:51:02,910 composition and information have been 1203 00:51:06,950 --> 00:51:06,000 ruled out already by the composition 1204 00:51:09,170 --> 00:51:06,960 data you're getting from the 1205 00:51:12,020 --> 00:51:09,180 spectrometers and what possible models 1206 00:51:14,620 --> 00:51:12,030 are still left so this is Larry knit 1207 00:51:16,790 --> 00:51:14,630 lair I'll take that question Lisa 1208 00:51:19,430 --> 00:51:16,800 there's a number of models of the 1209 00:51:21,770 --> 00:51:19,440 formation of mercury that were proposed 1210 00:51:24,380 --> 00:51:21,780 after the Mariner 10 observations in the 1211 00:51:27,110 --> 00:51:24,390 1970s indicated it had an unusually 1212 00:51:31,160 --> 00:51:27,120 large core and one of these models was 1213 00:51:33,140 --> 00:51:31,170 that the planet formed at normally or 1214 00:51:35,210 --> 00:51:33,150 similarly to the earth and had a 1215 00:51:36,800 --> 00:51:35,220 normal-sized core meaning earth-sized 1216 00:51:40,070 --> 00:51:36,810 core relative to the radius of the 1217 00:51:42,530 --> 00:51:40,080 planet and then because the Sun went 1218 00:51:44,650 --> 00:51:42,540 through a phase of extreme high 1219 00:51:47,180 --> 00:51:44,660 intensity in its earliest stages 1220 00:51:50,360 --> 00:51:47,190 essentially mercury was so close to this 1221 00:51:52,850 --> 00:51:50,370 to this hot Sun that the outer layers 1222 00:51:54,470 --> 00:51:52,860 could have evaporated off and in this 1223 00:51:55,940 --> 00:51:54,480 model this would have predicted very 1224 00:51:59,030 --> 00:51:55,950 very low abundances of things like 1225 00:52:01,300 --> 00:51:59,040 potassium and sulfur and sodium so we 1226 00:52:05,120 --> 00:52:01,310 can rule out this this kind of model 1227 00:52:07,550 --> 00:52:05,130 there are other models that proposed 1228 00:52:11,240 --> 00:52:07,560 that mercury formed from a specific kind 1229 00:52:14,210 --> 00:52:11,250 of meteorite called a CB chondrite that 1230 00:52:16,100 --> 00:52:14,220 are very very rich in metal now these 1231 00:52:19,490 --> 00:52:16,110 models make very specific predictions 1232 00:52:21,950 --> 00:52:19,500 for the composition of lavas and rocks 1233 00:52:24,110 --> 00:52:21,960 at the surface of the planet and for the 1234 00:52:25,640 --> 00:52:24,120 most part these are not in detail not in 1235 00:52:27,740 --> 00:52:25,650 agreement with our observations so these 1236 00:52:29,990 --> 00:52:27,750 models in detail can be ruled out but 1237 00:52:34,280 --> 00:52:30,000 possibly variations on them will 1238 00:52:36,830 --> 00:52:34,290 eventually be proven to be right another 1239 00:52:40,300 --> 00:52:36,840 model is that it formed mercury formed 1240 00:52:42,920 --> 00:52:40,310 larger and similarly to the earth and 1241 00:52:45,590 --> 00:52:42,930 after it had formed a earth or moon like 1242 00:52:47,870 --> 00:52:45,600 crust a another planet hit it and 1243 00:52:48,410 --> 00:52:47,880 smashed off the outer crust and part of 1244 00:52:50,180 --> 00:52:48,420 the mental 1245 00:52:52,370 --> 00:52:50,190 leaving a residual mantle that could 1246 00:52:54,320 --> 00:52:52,380 have then produced a new crust at this 1247 00:52:56,450 --> 00:52:54,330 stage we cannot rule out this model the 1248 00:52:59,330 --> 00:52:56,460 data some of our compositional data are 1249 00:53:01,580 --> 00:52:59,340 certainly consistent with this this idea 1250 00:53:04,100 --> 00:53:01,590 in broad outlines whether the high 1251 00:53:06,620 --> 00:53:04,110 sulphur abundance is consistent with 1252 00:53:08,420 --> 00:53:06,630 this we have not yet figured out but 1253 00:53:11,330 --> 00:53:08,430 this is a model that's still still in 1254 00:53:13,760 --> 00:53:11,340 the running and they're probably going 1255 00:53:15,470 --> 00:53:13,770 to be many more models devised before we 1256 00:53:18,580 --> 00:53:15,480 have an answer on this as we continue to 1257 00:53:21,410 --> 00:53:18,590 get interesting data but thank you all 1258 00:53:25,100 --> 00:53:21,420 next question will be from Peter spot oh 1259 00:53:26,960 --> 00:53:25,110 thank you thanks Lisa next question will 1260 00:53:28,550 --> 00:53:26,970 be Peter spots on the christian science 1261 00:53:30,470 --> 00:53:28,560 monitor with the christian science 1262 00:53:32,780 --> 00:53:30,480 monitor and actually good that pretty 1263 00:53:35,260 --> 00:53:32,790 much was like can you hear me so great 1264 00:53:39,740 --> 00:53:35,270 great Pete am I getting through yes I 1265 00:53:41,030 --> 00:53:39,750 guess so okay yeah that that actually 1266 00:53:43,430 --> 00:53:41,040 answered most of my question but let me 1267 00:53:47,720 --> 00:53:43,440 just throw one one other one related to 1268 00:53:50,720 --> 00:53:47,730 that and is is there any possibility for 1269 00:53:53,240 --> 00:53:50,730 a migration of mercury from forming in a 1270 00:53:58,340 --> 00:53:53,250 bit more distant location in the solar 1271 00:54:01,910 --> 00:53:58,350 nebula and somehow migrating in I can 1272 00:54:04,250 --> 00:54:01,920 take that Pete this is Sean Solomon the 1273 00:54:06,290 --> 00:54:04,260 process I think you know or you would 1274 00:54:10,490 --> 00:54:06,300 have asked this question of building up 1275 00:54:13,190 --> 00:54:10,500 the inner planets is a is is one with a 1276 00:54:16,580 --> 00:54:13,200 lot of chance encounters we would call 1277 00:54:20,840 --> 00:54:16,590 it stochastic that the interaction of 1278 00:54:25,910 --> 00:54:20,850 growing objects that start out many and 1279 00:54:29,150 --> 00:54:25,920 become few is not fully predictable and 1280 00:54:32,180 --> 00:54:29,160 depends on particular encounters that 1281 00:54:34,760 --> 00:54:32,190 that can result in in growth of a larger 1282 00:54:37,010 --> 00:54:34,770 object or disruption of an object and 1283 00:54:38,960 --> 00:54:37,020 some of those simulations that have been 1284 00:54:42,920 --> 00:54:38,970 done of the growth of the inner planets 1285 00:54:46,010 --> 00:54:42,930 do include the possibility that mercury 1286 00:54:49,310 --> 00:54:46,020 started to form at a different place in 1287 00:54:52,780 --> 00:54:49,320 the the in solar distance then it ended 1288 00:54:55,370 --> 00:54:52,790 up my late colleague George wetherill 1289 00:55:01,170 --> 00:54:55,380 did some of the pioneering calculations 1290 00:55:05,250 --> 00:55:01,180 of that sort that said 1291 00:55:09,650 --> 00:55:05,260 uh there are also interesting studies of 1292 00:55:12,750 --> 00:55:09,660 the migration of planets once formed and 1293 00:55:14,549 --> 00:55:12,760 this was this work was really stimulated 1294 00:55:16,680 --> 00:55:14,559 by the discovery of extrasolar planets 1295 00:55:19,020 --> 00:55:16,690 near their host stars and a lot of the 1296 00:55:21,480 --> 00:55:19,030 attention has been directed at the major 1297 00:55:23,670 --> 00:55:21,490 planets whose migrations may have had a 1298 00:55:26,190 --> 00:55:23,680 big influence on the history of small 1299 00:55:28,020 --> 00:55:26,200 objects in the solar system but there's 1300 00:55:30,900 --> 00:55:28,030 a very interesting study by a French 1301 00:55:34,650 --> 00:55:30,910 dynamicists of the long term evolution 1302 00:55:37,170 --> 00:55:34,660 of planet Mercury and their simulations 1303 00:55:39,480 --> 00:55:37,180 have shown that some of the orbital 1304 00:55:42,569 --> 00:55:39,490 characteristics of mercury like the 1305 00:55:45,150 --> 00:55:42,579 large eccentricity of the orbit like the 1306 00:55:47,099 --> 00:55:45,160 large inclination that Mercury's orbit 1307 00:55:50,370 --> 00:55:47,109 makes with the orbits of most of the 1308 00:55:52,950 --> 00:55:50,380 other planets are not fixed in time but 1309 00:55:54,299 --> 00:55:52,960 evolve and they made a very interesting 1310 00:55:56,940 --> 00:55:54,309 prediction and a paper in Nature a 1311 00:55:58,890 --> 00:55:56,950 couple years ago that three and a half 1312 00:56:00,299 --> 00:55:58,900 billion years from now it's not 1313 00:56:04,109 --> 00:56:00,309 something we have to worry about next 1314 00:56:06,359 --> 00:56:04,119 week that there's a possibility that the 1315 00:56:09,630 --> 00:56:06,369 orbit of mercury will substantially 1316 00:56:14,160 --> 00:56:09,640 disrupt the orbit of one of the other 1317 00:56:16,020 --> 00:56:14,170 inner planets and so it's something that 1318 00:56:18,240 --> 00:56:16,030 our great-great-great great-great-great 1319 00:56:20,700 --> 00:56:18,250 grandchildren might devote some time 1320 00:56:22,950 --> 00:56:20,710 thinking about that that mercury and its 1321 00:56:24,990 --> 00:56:22,960 orbital evolution may have major 1322 00:56:28,829 --> 00:56:25,000 consequences for the orbit of our own 1323 00:56:32,069 --> 00:56:28,839 planet but that's a prediction that may 1324 00:56:34,079 --> 00:56:32,079 or may not be borne out according to an 1325 00:56:37,530 --> 00:56:34,089 article in nature but I can send you 1326 00:56:40,770 --> 00:56:37,540 that link if you're interested p okay 1327 00:56:43,470 --> 00:56:40,780 next up this Kelly BTW sky and telescope 1328 00:56:46,920 --> 00:56:43,480 magazine Kelly is it is it possible oh 1329 00:56:48,420 --> 00:56:46,930 go ahead go ahead yeah yeah people will 1330 00:56:49,890 --> 00:56:48,430 give you an opportunity to follow us 1331 00:56:52,349 --> 00:56:49,900 because we're approaching the top of the 1332 00:56:59,520 --> 00:56:52,359 hour so let's go ahead and go to Kelly 1333 00:57:01,079 --> 00:56:59,530 BTW at sky and telescope magazine thanks 1334 00:57:03,390 --> 00:57:01,089 very much i came in a little bit late so 1335 00:57:04,980 --> 00:57:03,400 Sean if you covered the possible 1336 00:57:06,839 --> 00:57:04,990 interior structure of the planet i 1337 00:57:08,700 --> 00:57:06,849 missed it but if you didn't if i didn't 1338 00:57:09,839 --> 00:57:08,710 can you say anything about the interior 1339 00:57:12,660 --> 00:57:09,849 structure of the planet and in 1340 00:57:14,700 --> 00:57:12,670 particular what an offset magnetic field 1341 00:57:20,310 --> 00:57:14,710 says about the state of the 1342 00:57:21,990 --> 00:57:20,320 okay Kelly you didn't miss much on 1343 00:57:26,250 --> 00:57:22,000 that topic and we didn't cover it a 1344 00:57:28,740 --> 00:57:26,260 great length we know on the basis of 1345 00:57:32,190 --> 00:57:28,750 measurements made with her earth-based 1346 00:57:34,050 --> 00:57:32,200 radar that the core the outer core of 1347 00:57:38,880 --> 00:57:34,060 mercury is molten like the outer core of 1348 00:57:40,770 --> 00:57:38,890 the earth molten metallic iron rich we 1349 00:57:42,180 --> 00:57:40,780 also know the approximate radius of the 1350 00:57:43,620 --> 00:57:42,190 core on that just on the basis of the 1351 00:57:46,890 --> 00:57:43,630 mean density the planet that's been 1352 00:57:48,510 --> 00:57:46,900 known for 50 60 years and it's a at 1353 00:57:52,490 --> 00:57:48,520 least three-quarters of the radius of 1354 00:57:55,050 --> 00:57:52,500 mercury what the asymmetry the 1355 00:57:59,070 --> 00:57:55,060 equatorial are the asymmetry about the 1356 00:58:01,140 --> 00:57:59,080 equator of the magnetic field means as 1357 00:58:06,599 --> 00:58:01,150 still to be sorted out by the theorists 1358 00:58:08,910 --> 00:58:06,609 but one possibility is that the field 1359 00:58:11,310 --> 00:58:08,920 generating region of the outer core or 1360 00:58:14,040 --> 00:58:11,320 the in particular the boundary between 1361 00:58:16,560 --> 00:58:14,050 the outer core and the mantle may be 1362 00:58:17,760 --> 00:58:16,570 strongly different in the Northern 1363 00:58:20,099 --> 00:58:17,770 Hemisphere and the southern hemisphere 1364 00:58:22,560 --> 00:58:20,109 this idea has been put forward as an 1365 00:58:26,220 --> 00:58:22,570 explanation for an early magnetic field 1366 00:58:27,750 --> 00:58:26,230 on Mars that hat is much stronger in the 1367 00:58:29,790 --> 00:58:27,760 southern hemisphere of Mars than in the 1368 00:58:31,950 --> 00:58:29,800 northern hemisphere to explain the 1369 00:58:35,160 --> 00:58:31,960 strong magnetic anomalies recorded in 1370 00:58:36,930 --> 00:58:35,170 crustal rocks on Mars and their 1371 00:58:39,480 --> 00:58:36,940 locations which are dominantly in the 1372 00:58:42,859 --> 00:58:39,490 southern hemisphere so I have no doubt 1373 00:58:45,750 --> 00:58:42,869 that our new results on Mercury's 1374 00:58:48,740 --> 00:58:45,760 magnetic field geometry is going to 1375 00:58:50,940 --> 00:58:48,750 stimulate a variety of new ideas for how 1376 00:58:53,670 --> 00:58:50,950 Mercury's magnetic field has generated 1377 00:58:55,890 --> 00:58:53,680 how that field might vary with time how 1378 00:58:58,470 --> 00:58:55,900 it varies with position and I look 1379 00:59:02,339 --> 00:58:58,480 forward to those models and to our 1380 00:59:04,440 --> 00:59:02,349 ability to test them okay folks are we 1381 00:59:06,000 --> 00:59:04,450 are going to have to wrap up here at the 1382 00:59:07,950 --> 00:59:06,010 top of the hour for the media who are 1383 00:59:10,470 --> 00:59:07,960 still on the line please get in touch 1384 00:59:13,740 --> 00:59:10,480 with my office or apo public affairs to 1385 00:59:15,900 --> 00:59:13,750 get some follow-up questions and 1386 00:59:17,910 --> 00:59:15,910 interview set up for later in the day I 1387 00:59:19,980 --> 00:59:17,920 want to thank you all for showing up in 1388 00:59:23,310 --> 00:59:19,990 joining us today congratulations to the 1389 00:59:26,400 --> 00:59:23,320 messenger team again go to ww any say 1390 00:59:27,970 --> 00:59:26,410 gioves last messenger science never