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

    Comment number 58.

    Mars is a very interesting place to explore; it's uncannily like Earth. It has a day-length of just over 24 hours. It has an axial tilt very similar to Earth, so it has the same seasons. It has polar ice caps, dried out river deltas and tornadoes.
    Main difference is it doesn't have a magnetic field, which means the atmosphere gets stripped away, and no liquid water can exist on its surface. Damn.

  • rate this

    Comment number 57.

    Shows how the media can slant public opinion - do we get a gold here? How can this be "news"?

    Scary ;)

  • rate this

    Comment number 56.

    I am really looking forward to seeing whether this landing is a success.
    If NASA do manage to pull it off it leaves the way open for other missions to deliver what's necessary prior to a manned landing & the establishment of a base.
    This mission is essentially a geological survey & I am sure that lots of interesting discoveries will come out of it.
    Good luck to the scientists working on it.

  • rate this

    Comment number 55.

    @47 fuzzy

    "Remember, science is a self correcting method, that's why it's so sucessful. It doesn't depend on the scientist's prejudices".

    In theory,

    (see what I did there?)

  • rate this

    Comment number 54.

    53.Higgs bosun
    Thank you Higgs Bosun. I thought for a moment I was the only one not swept up in the madness and hysteria of the Olympics. Pray God it ends soon.

  • Comment number 53.

    All this user's posts have been removed.Why?

  • rate this

    Comment number 52.

    "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". This is what the superstitious call "tempting fate". Let's see if the dam' thing lands first.

  • rate this

    Comment number 51.

    I had a chat with a friend of mine, who actually is a rocket scientist, and the skycrane, while it looks horribly complicated, is no more complex than those toy quadcopters - in fact less so as with using jets instead of rotors it has less to worry about with atmospherics. The calculations are simple enough that they now appear in toys, I'll be surprised and sad if it doesnt work here.

  • rate this

    Comment number 50.

    19. Findlay
    >>>Rather sort this planet out before we start polluting others.
    That's the either/or argument. We can do space exploration AND try to look after our own planet. Money spent on increasing human knowledge is never wasted (even though the paybacks are often very long term).

  • rate this

    Comment number 49.

    4 Minutes ago
    when kicking a ball around a field is rewarded with a princes ransom, where self-interest is revered over altruism -

    Once upon a time, people would buy magazines on the workings of Wireless, TV and Mechanics etc. Now they're more interested in mags detailing the activities of "celebrities".

  • rate this

    Comment number 48.

    In the age of offshore outsourcing, where globalisation means obscene profit, when bank bail-outs suck the life out of whole continents, when kicking a ball around a field is rewarded with a princes ransom, where self-interest is revered over altruism - it is refreshingly inspirational to know that people dedicate their lives to the pursuit of knowledge for the benefit of all humanity.

  • rate this

    Comment number 47.


    34 Fuzzy.

    Did some thinking, tried a bit of science.

    Conclusion: Scientists are a bunch of egoists.
    Even if it's true, what does it matter? Remember, science is a self correcting method, that's why it's so sucessful. It doesn't depend on the scientist's prejudices.

  • rate this

    Comment number 46.

    Surely its time to stop sending rovers & send real people to investigate, its in our nature to be curious hence the name of this rover. Its taken us 50 years since getting a man on the moon a natural progression you would think to reach out further. Surely now is the time to think BIGGER and want more from our discoveries???

  • rate this

    Comment number 45.


    34 Fuzzy.

    Did some thinking, tried a bit of science.

    Conclusion: Scientists are a bunch of egoists.
    If you mean all scientists are egoists then I suggest you read about Michael Faraday. Try googling "faraday self effacing" and at least read the stuff on amazon.
    PS. You may have convinced youself, but you need to subject your method to scutinty by others in case you're mistaken.

  • rate this

    Comment number 44.

    7 Minutes ago
    34 Fuzzy.

    Did some thinking, tried a bit of science.

    Conclusion: Scientists are a bunch of egoists.


    Fortunately for you, there are people who are prepared to do a lot of thinking and a lot of science.

  • rate this

    Comment number 43.

    Indeed it is quite exciting, but judging by some of the readers comments below, it seems it is the first ever landing on Mars....which it clearly isn't. Its certainly not exciting enough to take a day off work for.

  • rate this

    Comment number 42.

    34 Fuzzy.

    Did some thinking, tried a bit of science.

    Conclusion: Scientists are a bunch of egoists.

  • rate this

    Comment number 41.

    Bad news - its not 4B years till earth toast, in 1B moon orbit drifts to far from earth to sustain ecosystem (tides, atmosphere burn off).

    We better speed up the space program to colonize space 3B years sooner.

  • rate this

    Comment number 40.


    After a vast outlay of money we will know if there was once water on Mars, well whoopee. Won't make one bit of difference to anyone on Earth. Apart, of course, from the scientists who will reap huge grants. Rather sort this planet out before we start polluting others.
    If we waited till all problems were solved we'd never do any science. Science helps solve (yes,and make) problems.

  • rate this

    Comment number 39.

    It's the old joke. This aircraft is totally automatic and we want to assure that absolutely nothing can go wrong, go wrong, go wrong, go wrong, go wrong !

    P.S. I am scientist (immunologist) and I don't think I'm egotistical.


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