many of us expected this would be a
mission of major discovery but none of
us really expected the degree of
discovery the degree of diversity which
we found in the outer solar system we
were lucky we had the unique opportunity
to explore planets that man had never
been to before but Voyager didn't only
carry sophisticated instrumentation it
carried the hearts and the minds of its
creators and all of us who were
privileged enough to see what it saw and
it will be unique for a long time
because there isn't anything else out
there to to explore for which you can
get as much return from a single system
I think Voyager will be remembered as
part of the few decades where human race
left its planet and Voyager will be a
main chapter in that book
Voyager kind of opened up the outer
planets to everybody and I think they
were vastly more interesting to me
expected up to and including maybe even
especially Neptune you only explore
explore the solar system for the first
time once and
and we did it
the outer planets are giant planets
they're distinctly different than the
smaller rocky objects in the inner solar
system such as Earth Mars Venus and
Mercury and Voyager was designed to open
up to exploration these giant outer
planets which are spheres of rotating
fluid gas surrounded by 57 moons totally
each planet has a unique ring system and
they have magnetic fields which were
immense compared to the magnetic field
of Earth voyagers job was to explore
those worlds in the outer solar system
scientists at Cape Canaveral Florida
sent another unmanned Voyager spacecraft
on its way to Jupiter and Saturn today
it lifted off flawlessly at 8:56 a.m.
and had none of the problems of the
Voyager launched two weeks ago this
voyager presumably will get to Jupiter
in March of 1979 Lord you're too scared
us
Voyager 2 had problems in separating
from the solid rocket kick stage the
spacecraft today you know have a few
problems but most of these problems were
problems we experienced early on there
was the the Voyager 2 spacecraft has a
failed receiver and and a sick backup
receiver that's the most serious problem
on board that spacecraft
the way we communicate with the with the
Voyager spacecraft is that we send
commands to the spacecraft series of
digital bits and computer language that
go to the spacecraft and it's the
language that the spacecraft understand
understands these bits are transmitted
and from ground stations located around
the earth what we call the Deep Space
Network the three deep space network
stations are located in Goldstone
California outside of Madrid Spain and
outside of Canberra Australia as the
Earth turns we can maintain Kamiya
continuous communication with the point
in space the spacecraft in turn there's
kind of the reverse link coming back
down the information that the spacecraft
gathers goes into a transmitter on the
spacecraft it's transmitted into those
big ears and the ground of the deep
space network and transmitted back then
on the ground to our control facility
here in Pasadena the transmitter on
Voyager is like tens of watts it's like
20 watts less power than an average
light bulb on your front porch
on the other hand when that signal is
received on the earth it is literally a
tiny tiny fraction of a watt that has
received the amount of power received by
the ground antennas is something like a
billion of the amount of power used by
my digital watch
man is known about the planet Jupiter
ever since he took a good look at the
night sky it's not what you'd call a
near neighbor though being more than
four hundred million miles away but
after all these centuries were getting a
closer look than we've ever had when
Voyager got up close and we looked at
the time-lapse movies of the atmosphere
in motion things were changing every day
little storms would pop up out of
nowhere and they'd get ripped apart
dispersed all in a day or two and that
made the mystery of the Great Red Spot
and all those other large spots even
deeper because how could they last for
so long in the midst of all that chaotic
motion it was a startling discovery as
Voyager approached Jupiter the first
thing that inter intercepted was what's
called the bow shock that's a shock
where the supersonic solar wind becomes
subsonic and that shock the solar wind
velocity which is a million miles per
hour abruptly decreases to 250,000 miles
per hour that abrupt change in velocity
causes the ionized gas to vibrate and we
can sense we can hear the shock and we
can hear the vibrations associated with
that shock as a spacecraft flew through
the shock itself
we had expected that the magnetic field
might expend something like a million
miles or so from the planet in fact it
extends some three to four million miles
from the planet now we understand
because IO is injecting into the
magnetic field some 1 to 2 tons of
material every second that material as
it spins with Jupiter is centrally
expanding Jupiter's magnetic field
inflating it to a much larger size than
it would normally be we expected quite
frankly the satellites of the outer
solar system to be quite bland and
geologically lifeless is we've flew
closer I look less and less like
anything we've ever seen the impact
craters turned into a regular dark
patterns and the colored patches red
yellows painted on the surface as a
matter of fact as we flew closer we saw
nothing at all that resembled an impact
crater if Voyager 1 discovered 11 active
volcanoes and 9 of those were still
active when Voyager 2 returned four
months later I think the the event in
the end the omission which really
altered our view and our expectation for
the rest of the mission was the
discovery of the volcanoes an isle that
was such a dramatic and unexpected thing
to find that it really told us that we
could no longer be complacent we could
no longer expect to understand or
anticipate what we were really going to
see Voyager 1 flew in close to Isle for
a close up flyby of IO to give good
return from Isle and made its close
encounters with the Galilean satellites
after the closest approach of Jupiter
if we look at Callisto it's one of the
most heavily cratered objects in the
solar saturated with impact craters when
we looked at Ganymede we find two kinds
of terrains one is a terrain looks very
much like Callisto but in addition
Ganymede has a
very complex intercepting network of
faults in a younger terrain which has
evidently welled up from the interior
and replaced these this old cratered
terrain is so similar to crystal the
case of Europa we see yet another style
we see gargantuan fault patterns in
which this ocean has frozen repeatedly
broken open and fluids float up to the
surface producing dark puddles of
material within the faults these are
then broken again so there's
intersecting and cross-cutting networks
there were two small satellites
discovered at Jupiter one of them found
orbiting just outside a very thin
tenuous ring of material that was
discovered the Jupiter the imaging team
members planned one single photo an 11
minute exposure that would be taken as
the spacecraft plunged through the
equator plane of Jupiter and it just so
happened that there was a ring there
it's dusty
there it seems to be no indication of
water or ice within the ring so it's
probably a minute of rocky material an
outerspace spectacular that was the
stuff of dreams only a generation ago
began snapping into the sharp focus of
reality today after its billion mile
journey from Earth to Voyager 1
spacecraft sent back pictures of man's
closest look yet at the ringed planet
Saturn
the closest encounter of spacecraft and
planet occurs later tonight when Voyager
sails just 77,000 miles from Saturn's
yellow clouds but already one scientist
said in the strange world of Saturn's
rings the bizarre has become commonplace
the closer that Voyager got to Saturn
the more and more detail and structure
Saturn's rings turned out to have and
this just was an enormous surprise to
everybody the Rings were simultaneously
breathtaking but completely baffling and
there was just far more structure than
people had anticipated not only did we
find many many concentric features
within the Rings but we found eccentric
rings we found that the F frame which
had been discovered by pioneer had
braids in it and kinks and clumps all
these things no one had ever even
dreamed about before Voyager got to
Saturn
and then of course they were the spokes
that Voyager discovered about a month or
month and a half before encounter and
these are these radial features in the B
ring that come and go they are seen
orbiting around the Rings and no one had
a clue or at least not a yeah not a
reasonable clue in the beginning as to
what caused these features or even what
they were that if you look at the rings
of Saturn it for a period of time and
watch the spokes go around and round and
you examined the appearance of the
spokes on the Rings that appearance
changes and it changes with a period
that is equal to the period of the spin
of Saturn's magnetic field voyager found
that Saturn's the magnetic field as
pioneer 11 had already told us is is
weaker that is it's only about
one-twentieth the strength of Jupiter's
magnetic field that means it's magnetic
field doesn't extend as far from the
planet about a million miles from the
planet
what Voyager discovered was how rapidly
that magnetic field was rotating the
magnetic field of Jupiter rotates with a
period just under ten hours at Saturn it
turns out the magnetic field rotates
with a period of about 10 hours and 40
minutes so this was the first measure of
the length of the day on Saturn turns
out when we finally measured the
magnetic field and the radio emissions
that are tied to the magnetic field that
the inside of Saturn is moving quite
slowly it's moving more slowly than most
of the storms in the atmosphere and that
the difference in those speeds
translates to 500 meters per second for
the winds which is over a thousand miles
an hour
and that made Saturn a lot windier
planet than Jupiter that was the big
surprise for me and we went Voyager got
there
Voyager 1 approached Saturn in such a
way that it flew past Titan before its
closest approach to Saturn that
trajectory then because of the tilt of
the satellite system around Saturn
caused the spacecraft to fly low
initially and then get deflected as it
made its closest approach to Saturn
going through the ring plane up out of
the plane of the ecliptic
we knew that Titan had an atmosphere we
had no idea how deep it was or what it
was made out of and what Voyager found
was a nitrogen atmosphere with traces of
methane and other hydrocarbons and it
was turned out to be quite a batma
sphere we suspect there might be an
ocean of material called ethane
there could be all kinds of complicated
hydrocarbons of different colors and
different states some ices some fluids
there's all manner of hallucination
about hydrocarbon goop that rains out of
the atmosphere and falls on the surface
as matter of fact Titan remains one of
the really exciting challenges for
future future exploration in the case of
limas we see a crater on - that's about
40% of its diameter a little larger and
that would have been enough to shatter
the object and of course we wouldn't see
the crater then because it would really
like a kind of a giant ball of sand and
in the case of Tethys there's another
very large crater even larger than the
one on
- but in that case notice the floor has
is now rounded out so that it is curved
as the rest of the object slain is the
case of Diana you'll notice that most of
the surface is pretty bland and only in
this one region near the trailing
hemisphere do we see a lot of detail on
the surface here we see a lot of Criss
crossing faults with wispy bright
markings around them finally we look at
Enceladus we're talking about very cold
regions and here we are with this little
tiny object showing geologic activity of
the scale that Enceladus does in which
the ancient cratered terrain has been
broken and has collapsed into the
interior fluids have flowed out into
those open gashes in the crust
repeatedly well after we got Voyager 1
to Saturn we went back to NASA and said
we have now satisfied all of the
objectives for the MJS for the Voyager
mission how about giving us money and
giving us permission to target Voyager
to tweak its trajectory just a little
bit so that we can go on to Uranus it
was a penalty for this the data that we
got
the quality of the mission at Saturn was
a little bit less if we targeted for
Uranus and it would be if we optimized
percent and we bared all those facts to
NASA we told them that it was maybe a 60
70 percent chance but we thought it was
worth it and I guess we were pretty
persuasive because they bought the idea
soon after Voyager twos closest approach
to Saturn in fact while it was behind
the planet its scan platform got stuck
at a mechanical failure and we weren't
able to aim the cameras and the other
pointable instruments on the spacecraft
at the targets after several years we
concluded that in fact during the Saturn
encounter we had moved this platform too
much too fast and that if we used the
platform in a consistently slow at a
slower rate and if we constrained the
total amount of angular motion that we
applied to the platform then in fact we
would be in a pretty safe condition
Voyageur to the amazing robot spacecraft
that was launched eight and a half years
ago and just kept on going past yet
another milestone today as it became the
first spacecraft to fly past the planet
Uranus Uranus is not a very photogenic
place it looks more or less like a big
blue ping-pong ball but we did see
clouds in the atmosphere of Uranus and
they did tell us something
in fact Uranus is a tipped-over version
of Jupiter and Saturn the cloud patterns
are more muted but they have the same
kind of banded structure that Jupiter
and Saturn have now what that says is
that the spin of a planet is the
all-important process or thing that
organizes whether Uranus is a very
peculiar plant in the sense it's tipped
on its side right now with the south
polar region headed pointed at the Sun
we had expected that the magnetic field
pole would also be up near the
rotational axis so the magnetic field
would be tipped on its side what we
found was to everyone's surprise that
the magnetic field rather than being
pointed at the Sun was tilted some 60
degrees from the rotation axis not only
that but the center of the magnetic
field was displaced from the center of
the planet by almost a third of the
radius of the planet Uranus is magnetic
field is a bit stronger than that on on
Saturn and it extends some 300,000 miles
from the planet the rotation period that
is the length of the day on you and this
is measured by how rapidly the magnetic
field rotating is about 17 and a quarter
hours the big problem going on to Uranus
is that it's twice as far away from the
earth as Saturn is in order to
compensate for the the darker
environment we had to make sure that the
spacecraft would be steadier and to make
the spacecraft steadier we had to deal
with the things that made the spacecraft
move well
flying through space the Iranian rings
are inherently dark in fact they are no
brighter than coal dust so imagine
trying to take an image of coal dust at
Twilight but it's even worse than that
so we had to worry about the necessity
of using long exposures and the fact
that the spacecraft scan platform is not
a stable platform and always move
someone best image that we got in fact
of the Iranian ring system we had to use
image motion compensation what we saw in
that image is a sheet of dust that
extends throughout the iranian ring
system and this sheet of dust is
punctuated by by features many of them
there are more features in that picture
than there are rings seen from inbound
so we have nine narrow rings seen in the
inbound images and one newly discovered
one the lambda ring as a matter of fact
if we had our choice we never would have
gone close to Miranda in order to get to
Neptune we were obliged to go a
particular distance from Uranus in order
to get the right gravitational
deflection on the spacecraft well turned
out that that distance was exactly the
distance that Miranda's orbit is from
Uranus it is a very exotic and
complicated place most of the regions
that we viewed are heavily cratered cold
rolling in chatterings but embedded in
these are very unusual circular patches
almost like racetracks of groove
terrains that run around in circular
bands surrounding very complicated Criss
crossing structures in the interiors
we address the the question what can we
do to hear the data better we did come
up with a technique called a rang where
we took existing antennas and
electronically wired them together so
that in fact it had the appearance of
being one larger antenna and we did that
in Australia the primary receiving site
at Uranus and combined the DSN stations
with a borrowed antenna from the
Australian radio at Radio Astronomy
community at Parkes I stand by part
while we were moving from uranus and
neptune on the ground we had two major
things to do first of all we
reprogrammed the software and board the
spacecraft to do two things to stabilise
the spacecraft so the pictures would not
be smeared and to add some new
techniques to the spacecraft it will
allow it to pan and track the planet
when we were taking pictures near the
planet second thing we had to do is
improve the communications capability we
did that since the since neptune is
twice as far away from the communication
standpoint as uranus we did that by
enlarging the size the antennas on the
earth and by adding several new sets of
antennas into our deep space network to
help compensate for the distance
it is mission accomplished for Voyager -
the space probe is headed out of the
solar system tonight after photographing
parts of the universe no one had ever
seen before now we had some hints from
earth-based observations that Neptune
had a few clouds and it was that was
better than Uranus but we really weren't
prepared for the spectacular weather
activity that was found in fact
Neptune's the windiest planet in the
solar system and I was totally
unprepared for that the winds are 325
meters per second that's the speed that
the great dark spot is moving relative
to the inside of Neptune everything's
going to the east but the great dark
spot is going more slowly to the east
than the inside of mention we had
expected because Neptune does is not
tipped on its side as a planet but is an
upright planet that the magnetic field
acts with axis would be aligned with the
rotation axis that is the poles would be
near the rotational pole we were
surprised again the magnetic field is
tilted by 47 degrees in the case of
Neptune and it's center of the magnetic
field is offset by almost two-thirds of
the radius of the planet its magnetic
field is somewhat weaker only about half
of that of Saturn's for instance at the
surface and its magnetic field extends
only about 400,000 miles from its
surface we did discover that the
rotation period of the magnetic field is
about 16 and hours and 7 minutes faster
than Uranus but slower than both Cupit
ER and Saturn
yes I'd like to report the scam as we
approach Neptune we were approaching
with the Sun and the earth almost
directly behind us so you can see we're
virtually a full disk of Neptune and we
aimed to go right over the North Pole
right up over the top of Neptune very
very close to Neptune the trajectory is
then bent by gravity moved south and we
intercepted Triton while it was behind
the up tun and underneath it well as we
got closer and closer to Triton it got
smaller and smaller and smaller and at
the same time brighter and brighter
turned out to be the brightest thing
we've seen in the solar system north of
the polar cap in the North just above
the equator we find one thing we call
the cantaloupe terrain it has a system
of criss-crossing ridges which produce a
set of almost squarish to ovoid dimples
throughout the surface now we're talking
about a surface which is 37 degrees
above absolute zero this is a coldest
thing in the solar system by far even
the cold atmospheres of things like
Neptune are warmer it was unthinkable to
find activity going on a planet whose
surface temperature is that low I mean
this is getting down a point with
molecules stop it was about a month
after the Reuter encounter that we were
looking at stereo images way down in the
southern most part of tritons polar cap
and we saw most of the features lined up
as if they were on a perfect sphere in
fact the two best examples turn out to
be active RUP shion's in which material
is being blown from the surface in a
vertical column to an altitude of 8
kilometers roughly 5 miles
Roger discovered six new moons at
Neptune
two of them were found in the ring our
core ring system orbiting along two of
the ring arcs so apparently shepherding
the edges of those ring arcs in some way
when we look at Neptune's ring system as
we can see here in this mosaic we see
three continuous rings quite easily
there is an outer ring
it's the ring in which in fact the three
arcs are embedded there's an inner ring
which at in high phase geometry appears
brighter than the outer ring that tells
us right away it's dusty dustier than
the outer ring and then we see an inner
more diffuse ring at something like 42
thousand kilometers from the centre of
this of the planet we believe now that
we'll be able to communicate with
Voyager essentially as long as it stays
alive two things will probably stop its
life
first of all it has a power source on
board which is a small nuclear power
source called radioisotope thermal
radioactive decay of plutonium which
generates heat which in turn is
converted into electricity in about 20
to 25 years we expect to be low enough
so that there's not enough power to keep
the critical subsystems of the
spacecraft operating or at about the
same time we could possibly run out of
attitude control fuel that's the fuel
which goes to the little thrusters which
keeps the spacecraft stabilized and
pointed at the earth now between the
stars is a dilute gas ionized gas
filling interplay interstellar space
it's called the interstellar medium
each star blows a bubble in that
interstellar gas our own Sun does that
that bubble in the case of our Sun is
called the heliosphere we don't know how
large that bubble is it may be that the
distance to the edge of the bubble
called the heliopause is a hundred times
the distance from the earth to the Sun
that is three times further than it is
out to Neptune in which case 25 years
Voyager 1 which will at that point be a
hundred and thirty times as far from the
Sun as the earth could well be returning
data from
interstellar space for the first time
there will be a part of earth which will
roam essentially forever in the galaxy
and that will be the Voyager spacecraft
you