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6. Mars Up Close
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From the course by University of Arizona
Astronomy: Exploring Time and Space
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The Solar System
Space probes have visited most planets in the Solar System, and orbiters and rovers are homing in on the habitability of Mars. Space exploration is entering an entrepreneurial phase that might let us venture beyond the Solar System.
Meet the Instructors
Chris ImpeyDistinguished Professor
Astronomy
The last decade of orbiters, landers and
rovers have given us an unprecedented look at the Mars surface.
So let's take a look at Mars up close.
Here's a typical Martian feature.
The craters that are seen all over Mars, in this case superimposed with
a gorgeous sand dune textured by the winds that circulate on the surface.
Sometimes at over 100 miles an hour,
occasionally whipping up dust storms that are longer than the United States.
A mission operated out of the University of Arizona by the Lunar and
Planetary Lab, has been taking extraordinary images at close to 1
meter resolution across most of the surface of Mars.
The altimetry from the orbiters can be used to recreate realistic
three-dimensional trajectories across the planet,
as if we were sweeping over these surface features.
[MUSIC]
Two of the most extraordinary missions sent to Mars are small,
no bigger than a child's go-kart.
They're the Spirit and Opportunity Mars rovers,
which in each case have done their work for over six years.
And one of them continues into it's eighth year.
These missions were only designed to last 90 days and travel less than a mile.
They've out done their spec by an order of magnitude or
more, extraordinarily successful missions.
Identical hardware that has suffered quite different fates on the Martian surface and
had different adventures.
Spirit and Opportunity did not provide the first evidence of water on Mars, but
by looking at minerals up close and doing chemical analysis,
they've cemented the idea that the Martian surface, at one point, had water on it.
First, let's celebrate Spirit.
Spirit, unfortunately finally met its end after working its diamond bit so
much that it was blunted and
having one wheel that didn't work such that it had to drive in reverse.
Eventually, Spirit got stuck in a sand dune and was immobilized.
It was turned off and converted into a stationary science station a year or so
ago, and finally communication with Spirit was lost in early 2012.
[MUSIC]
Opportunity, its twin, continues its work into its eighth year,
having traveled an extraordinary 25 miles across the Martian surface.
And although we might have a mental image of someone at Houston Space Center with
a joystick and a cowboy hat on careening over a sand dune with a rover,
in fact these rovers move very carefully and methodically.
Rarely traveling more than the distance of a football field in a day.
[MUSIC]
>> It's been seven years since the rovers landed on Mars.
This was originally a 90 day mission, only three months.
>> The fact that they've lasted this long and
driven this far was in nobody's imagination.
>> Opportunity has crossed almost 26 kilometers of odometry, and
it's still in very good health but that's amazing after seven years.
[MUSIC]
>> Opportunity's in kind of a desert track mode ever since we've left Victoria.
Opportunity now is located at Santa Maria Crater.
>> It's one of the freshest craters that either rover has had a chance to explore.
And there's also evidence of some hydrated sulfate
minerals around the southeast corner of this crater.
>> They can only form when there's been water along for
a really long period of time.
>> The next big adventure for that rover, and that's to get to Endeavour Crater
that's still some six kilometers away from where the rover is right now.
>> We're trying to do a balance of driving as fast as we can, but
making sure we don't miss anything critical as we drive.
Endeavour's such a large crater,
we might start seeing rocks ejected from Endeavour well before we get there.
>> That's our next big objective, because we know there are these
clay minerals present in the rim of Endeavor Crater,
that is suggestive of ancient water on Mars, that was of neutral ph.
Neutral water is what astrobiologists asses that life started in,
and so the fact that there is evidence of ancient,
neutral water on Mars is very exciting for the bio potential of the planet.
>> It's an exciting time over the next, year or
so while, while we get this under way.
>> Phoenix, out of the University of Arizona, was the first time that
NASA trusted any university to operate an entire mission except for the launch.
This project also brought a $350 million contract to my University.
Phoenix was based on a design that actually led to a failed mission that
plunged into the Martian surface.
They resuscitated the design, got all the bugs out and
did a very successful launch to the polar region.
Phoenix was not a rover.
It was a fixed platform.
But it actually watched the hydrological cycle in operation.
In fact, brining material was seen dripping down the leg of the lander.
When water has sufficient amount of salt or
other minerals, it can be liquid even at the cold Martian temperature.
It also saw a fine snow falling on one occasion,
an extraordinarily successful mission.
Our current rover on Mars, Curiosity or the Mars Science Lab, is just
beginning the heart of its mission after an adventurous and successful landing.
Curiosity steps up the size, the scale, and
the degree of difficulty of a Martian rover.
Compared to Spirit and
Opportunity, the size of go-karts, Curiosity is the size of an SUV.
Spirit and Opportunity landed on Mars in
bouncing balloon bags which were rather sensitive to problems of
the landing because they bounced to a halt protected by the balloons.
Curiosity, by contrast, used an audacious sky crane method which seemed to
have many ways that it could go wrong and yet it didn't.
Planetary scientist argued for years about where best to land on Mars.
If you have a billion dollar piece of hardware with no twin ready to go
if it fails, you better be sure when you want to land it.
In a series of conferences over three or four years,
they narrowed down from a hundred to 25 to four and finally to one landing site.
Think of it as a roulette game where you have to put all your money on one number.
The scientists chose Gale Crater because there's strong mineralogical evidence that
the Gale Crater was once a shallow seabed.
Minerals seen there are similar to the clays and silicates that are seen in
terrestrial regions of sedimentation, leading to the exciting prospect that
the Curiosity mission will be able to further give evidence of Mars' wet past.
Mars is busy enough with missions that the missions take pictures of each other.
Here's a picture of the Curiosity landing,
taken by the main Mars Orbiter at the time.
The Curiosity descent sequence was enough to give gray hairs to
all the people involved in the mission.
It was a complex sequence involving using the heat shield to
decelerate through the thin Martian atmosphere, the deployment of a parachute.
The separation of that heat shield, and then the scary part.
Lowering the rover on metal ropes and then deploying a sky crane to gently lower
it onto the surface while the spacecraft maintained an altitude of about 50 meters.
Then those cables were released and
the spacecraft flew off to crash land in the Martian surface.
There are at least six or seven places in this sequence where one mistake would have
spelled doom to the mission.
I've heard Peter Smith, the PI on the Phoenix Mission,
describe what it's like in the control room when a mission like this lands.
Essentially each group of engineer's responsible for one part of the landing
sequence is anxious and then celebrates as their part is concluded successfully.
And then all eyes pivot to the next group.
Basically, we didn't screw up, now it's your turn.
Eventually the baton is passed to last landing stage and
Curiosity landed on the surface, the softest possible landing imaginable.
[MUSIC]
>> Things are looking good.
Coming up on entry.
Vehicle reports entry interface.
[SOUND] Navigating to, field the atmosphere as we go in here.
[SOUND] Just reporting that we are seeing G's on the order of, 11 to 12 Earth G's.
[SOUND].
[MUSIC]
>> [APPLAUSE].
>> Universal two is starting.
We are now getting telemetry from Odyssey.
>> [SOUND].
[MUSIC]
>> We should have parachute deploy around Mach 1.7.
>> [SOUND].
[MUSIC]
The parachute is deployed.
[APPLAUSE] We are decelerating.
[MUSIC]
Fuselage has separated, we're on the ground.
We're down to 90 meters per second at an altitude of 6.5 kilometers descending.
[MUSIC]
Standing by for [INAUDIBLE] separation.
[SOUND] [SOUND].
>> We are in powered flight.
[APPLAUSE] [SOUND]
[MUSIC]
We're at altitude of one kilometer and descending.
[MUSIC]
[SOUND] Standing by for sky crane.
Sky Crane has started.
[SOUND].
[MUSIC]
>> Single remains strong
[MUSIC]
[SOUND].
[MUSIC]
Touch down confirmed.
We're safe on Mars.
>> [APPLAUSE]
[NOISE]
[APPLAUSE]
[NOISE] Real,
it's for real.
[CROSSTALK]
[MUSIC]
Curiosity is working slowly and methodically, and
has a wonderful suite of 12 instruments which will give detailed information on
the chemical situation and history of the rocks that it studies.
It's important to remember that Curiosity was never built as a life
detection experiment.
It will not look for DNA or nucleic acids.
And it will not really be able to tell if there are microbes hidden in the rocks.
For that, we'll need sample return.
But it's clearly a step up from the much smaller rovers that preceded it,
and its mission could last at least two years and perhaps as much as five years.
Mars is the watering hole, so to speak, for a wide range of NASA missions.
We've had orbiters and landers around Mars since the mid 1970s, but
the current generation are doing extraordinarily detailed work.
Mars orbiters can resolve everything down to the size of a football and
they can map the entire surface, not just in visual light, but in radar.
Able to detect sub-surface water.
The small and the extremely successful twin rovers Spirit and Opportunity,
one of which is still doing its work, have been superseded by the Curiosity rover,
the size of a small car, just beginning its scientific mission.
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