Gale Crater: Geological 'sweet shop' awaits Mars rover

 

Grotzinger leads a team of several hundred mission scientists

John Grotzinger is the project scientist on Nasa's latest multi-billion-dollar mission to Mars.

He's going to become a familiar face in the coming months as he explains to TV audiences the importance of the discoveries that are made by the most sophisticated spacecraft ever sent to touch the surface of another world.

The Curiosity Rover - also called the Mars Science Laboratory (MSL) - is set to land on Monday (GMT) for a minimum two-year exploration of a deep hole on Mars' equator known as Gale Crater.

The depression was punched out by an asteroid or comet billions of years ago.

The lure for Grotzinger and his fellow scientists is the huge mound of rock rising 5km from the crater floor.

Mount Sharp, as they refer to it, looks from satellite pictures to be constructed from ancient sediments - some deposited when Mars still had abundant water at its surface.

Gale Crater From orbit, Mount Sharp looks like Australia. Gale is named after an Australian astronomer.

That makes it an exciting place to consider the possibility that those distant times may also once have supported microbial life.

And Curiosity, with its suite of 10 instruments, will test this habitability hypothesis.

Grotzinger is a geologist affiliated to the California Institute of Technology and he recently took the BBC Horizon programme to the mountains of the nearby Mojave Desert to illustrate the work the rover will be doing on Mars.

He climbed to a level and then pointed to the rock sediments on the far side of the valley.

"What you see here is a stack of layers that tell us about the early environmental history of Earth, representing hundreds of millions of years," he told Horizon.

"They read like a book of Earth history and they tell us about different chapters in the evolution of early environments, and life.

"And the cool thing about going to Mount Sharp and Gale Crater is that there we'll have a different book about the early environmental history of Mars.

"It will tell us something equally interesting, and we just don't know what it is yet," he said.

Mission scientist Dawn Sumner describes the capabilities of some of the instruments on Nasa's Curiosity rover

Curiosity dwarfs all previous landing missions undertaken by the Americans.

At 900kg, it's a behemoth. It's nearly a hundred times more massive than the first robot rover Nasa sent to Mars in 1997.

Curiosity will trundle around the foothills of Mount Sharp much like a human field geologist might walk through Mojave's valleys. Except the rover has more than a hammer in its rucksack.

It has hi-res cameras to look for features of interest. If a particular boulder catches the eye, Curiosity can zap it with an infrared laser and examine the resulting surface spark to query the rock's elemental composition.

If that signature intrigues, the rover will use its long arm to swing over a microscope and an X-ray spectrometer to take a closer look.

Cross-section of minerals in Gale Crater

Still interested? Curiosity can drill into the boulder and deliver a powdered sample to two high-spec analytical boxes inside the rover belly.

These will lay bare the rock's precise make-up, and the conditions under which it formed.

"We're not just scratching and sniffing and taking pictures - we're boring into rock, getting that powder and analysing it in these laboratories," deputy project scientist, Ashwin Vasavada, told the BBC.

"These are really university laboratories that would normally fill up a room but which have been shrunk down - miniaturised - and made safe for the space environment, and then flown on this rover to Mars."

The intention on Monday is to put MSL-Curiosity down on the flat plain of the crater bottom.

The vehicle will then drive up to the base of Mount Sharp.

In front of it, the rover should find clay minerals (phyllosilicates) that will give a fresh insight into the wet, early era of the Red Planet known as the Noachian. Clays only form when rock spends a lot of time in contact with water.

Above the clays, a little further up the mountain, the rover should find sulphate salts, which relate to the Hesperian Era - a time when Mars was still wet but beginning to dry out.

"Going to Gale will give us the opportunity to study a key transition in the climate of Mars - from the Noachian to the Hesperian," said Sanjeev Gupta, an Imperial College London scientist on the mission.

"The rocks we believe preserve that with real fidelity, and the volume of data we get from Curiosity will be just extraordinary."

A roving laboratory for Mars

Model of rover
  • General equipment: MSL equipped with tools to remove dust from rock surfaces, drill into rocks, and to scoop up, sort and sieve samples
  • Mast Camera: will image rover's surroundings in hi-res stereo and colour; wide angle and telephoto; can make hi-def video movies
  • ChemCam: pulses infrared laser at rocks up to 7m away; carries a spectrometer to identify types of atoms excited in laser beam
  • Sample Analysis at Mars: inside body; will analyse rock, soil and atmospheric samples; would make all-important organics identification
  • Chemistry and Mineralogy: another interior instrument. Analyses powdered samples to quantify minerals present in rocks and soils
  • Mars Hand Lens Imager: mounted on arm toolkit; will take extreme close-ups of rocks, soil and any ice; details smaller than hair's width
  • Alpha Particle X-ray Spectrometer: Canadian arm contribution; will determine relative abundances of different elements in samples
  • Radiation Assessment Detector: will characterize radiation environment at surface; key information for future human exploration
  • Mars Descent Imager: operates during landing sequence; hi-def movie will tell controllers exactly where rover touched down
  • Rover Environmental Monitoring Station: Spanish weather station; measures pressure, temperature, humidity, winds, and UV levels
  • Dynamic Albedo of Neutrons: looks for sub-surface hydrogen; could indicate water buried in form of ice or bound in minerals

The rover is not a life-detection mission; it does not possess the capability to identify any bugs in the soil or huddled under rocks (not that anyone really expects to find microbes in the cold, dry, and irradiated conditions that persist at the surface of Mars today).

But what Curiosity can do is characterise any organic (carbon-rich) chemistry that may be present.

All life as we know it on Earth trades off a source of complex carbon molecules, such as amino acids - just as it needs water and energy.

Previous missions, notably the Viking landers in the 1970s, have hinted at the presence of organics on Mars. But if Curiosity could make the definitive identification of organics in Gale Crater, it would be a eureka moment and go a long way towards demonstrating that the Red Planet did indeed have habitable environments in its ancient past.

It's a big ask, though. Even in Earth rocks where we know sediments have been laid down in proximity to biology, we still frequently find no organic traces. The evidence doesn't preserve well.

And, of course, there are plenty of non-biological processes that will produce organics, so it wouldn't be an "A equals B" situation even if Curiosity were to make the identification.

Nonetheless, some members of the science team still dream of finding tantalising chemical markers in Gale's rocks.

Dawn Sumner, from the University of California at Davis, is one of them.

"Under very specific circumstances - if life made a lot of organic molecules and they are preserved and they haven't reacted with the rocks in Gale Crater, we may be able to tell that they were created by life. It's a remote possibility, but it's something I at least hope we can find," she said.

"I am confident we will learn amazing new things. Some of them will be answers to questions we already have, but most of what we learn will be surprises to us.

"We've only been on the ground on Mars in six places, and it's a huge planet.

"Gale Crater and Mount Sharp are unlike anything we've been to before. That guarantees we will learn exciting new things from Curiosity."

Horizon: Mission to Mars was broadcast on BBC Two Monday 30 July. Watch online via iPlayer (UK only) or browse more Horizon clips at the above link.

Mars maps
 
Jonathan Amos Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this
    +1

    Comment number 18.

    I am a scientist and love to learn new things, but JUICE sounds like a boring waste of time (sorry to be blunt, but it does). Surely so many other things that can be achieved and analyzed with less risk by 2030 (8 year flight time to Jupiter). However, agree that knowledge is priceless and the more we know the more we can understand.

  • rate this
    +3

    Comment number 17.

    Science Fiction become fact. Fantastic stuff and a credit to humanity’s curiosity and inventiveness. I can`t wait to see what is found

  • rate this
    +1

    Comment number 16.

    @2.Darren Shepperd
    "knowledge is priceless"

    Even more so when that knowledge is made freely available.

    Roll on 2022 when JUICE is launched (I hope).

  • rate this
    -2

    Comment number 15.

    I'd wait for it to land and establish contact with base before speculating

    Anyone here fancy landing in a pilotless jumbo jet? never mind a space re-entry vehicle x million miles from home

  • rate this
    +6

    Comment number 14.

    I still have this niggling feeling that the "skycrane" is too complex a system for the landing. I will have everything crossed until MSL is safely on the surface and sends home its first postcard.

  • rate this
    +10

    Comment number 13.

    How excellent to see that we are still investing resources and human capital in extending our reach, both in knowledge and exploration. A worthwhile counterbalance to so many things that could make you despair of humanity.

  • rate this
    +15

    Comment number 12.

    Perhaps the BBC could devote a special channel to this wonderful event rather than the Mclympics.

  • rate this
    +20

    Comment number 11.

    Humans has always looked up at the sky and wondered.


    I am glad to live in a time of such discovery!

  • rate this
    +4

    Comment number 10.

    @ #2 - in 4B years humankind will be a VERY long and distant memory on this planet, will be surprised if humankind makes it another 4K years. Back on the Mars issue though, I believe the day a human steps on Mars surface will be a momentous occasion and no matter the cost, it will be worth it. I would give my life (i.e., not to return if that be the case, to be that first person).

  • rate this
    +6

    Comment number 9.

    I have my fingers and toes crossed for a safe landing.

  • rate this
    +6

    Comment number 8.

    Just great stuff !!

  • rate this
    +19

    Comment number 7.

    I think this is absolutely fantastic, The technical challenges that have to be overcome to attempt this are huge. well done NASA. We are looking for previous signs of life on the planet next door effectively, it will be monumental to discover it, and very significant if we don't. yes we need not bother-but with that attitude nothing gets invented including the PC monitor your looking at now.

  • rate this
    +1

    Comment number 6.

    Elon Musk has comitted to a manned landing on Mars in 10+ years time.
    I'm excited by this mission but in two minds about it. Technologically, an autonomous instrument on a distant world is fascinating. However, with such incomprehensible chances of identifying "life", it means I find it difficult to wholly support the missions aims. Nonetheless, Ive booked a day from work to see the landing! :o)

  • rate this
    +5

    Comment number 5.

    It was in the year 1976 when I was in class 10, I saw the pictures of Viking landing on Mars in newspaper. We have immediate access to most scientific details on line. As post graduate student in physics I do believe that the Mars lander 'Curiosity' will rightly be a university science laboratory on Mars. It is like building scientific platforms to pave way for future robotic or human missions.

  • rate this
    -4

    Comment number 4.

    @2 Actually I do. However, with increasing economic crisis I doubt any govt is willing or capable to maintain the required funds. What I meant was a shot at the personal cults the media and ourselves to some degree tend to add to the canvas. On our move out into space? My, why I'd love to sign-up on one of the trips, I don't think that's going to happen any time soon.

  • rate this
    +1

    Comment number 3.

    I'm really excited about this, why is no-one commenting?

  • rate this
    +8

    Comment number 2.

    1.phhpro
    seems you dont realise knowledge is priceless and besides this is a logical next step on our move out into space. After all its only about 4B years untill the earth is toast no matter how good we look after it

  • rate this
    -8

    Comment number 1.

    By all means, if this thing works there's plenty to be discovered. For what's it worth.

 

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