Red destination: Choosing an ExoMars landing site

Bridget in the Desert

The search for a suitable site to land Europe's ExoMars rover in 2019 is about to begin.

A request will go out in the next few weeks to the scientific community, asking for expressions of interest to join a working group on the subject.

Once this panel is in place, planetary researchers will then be invited to a meeting, likely to be in the spring of next year.

This will formally kick-off the site selection process, which should take a couple of years to complete.

The European Space Agency's ExoMars rover - a roughly 350kg vehicle - is currently in the late stages of its design.

Its mission will be to scour the surface of the Red Planet for signs of past or present life.

It will have a drill to pull samples up from 2m down, and instruments to assess any organic chemistry that might be present.

Bridget in the Desert The "Bridget" ExoMars prototype is currently involved in trials in the Atacama Desert

But choosing the right place to go on Mars is critical to the whole endeavour.

"I expect before the end of this month to issue the call to the science community, asking them for letters of interest in becoming a member of the site selection working group," Jorge Vago, Esa's ExoMars project scientist, told me.

"We hope this will generate some buzz, and we hope to appoint the working group in November. It will consist of 10-12 external scientists, the project scientists and people from industry.

"I would expect by the middle of next year we should have zeroed in on about four top candidate sites to start studying in detail."

The scientific community will propose and argue the merits of various candidate destinations; new satellite imagery will be commissioned to inform the discussions.

"Best science" will not, however, be the only consideration in making the ultimate decision. There are very important engineering constraints as well.

No landing system yet devised can put down on a sixpence; the best you can hope for is a zone of confidence.

Even for the brilliant "skycrane" used by the American's Curiosity rover, there was an ellipse of uncertainty that measured 20km by 7km at the final estimate.

ExoMars' landing system is being constructed by the Russians and will be reminiscent of the Lunokhod Moon landers of the 1970s.

The expected error ellipse will be considerably larger - about 100km by 15km.

This means that wherever the scientists might like to go, the engineers will need to satisfy themselves that the rover can actually get there with minimal risk.

So, for example, Gale Crater, the current location of Curiosity, would appear to be off the list of potential destinations because the Russian system will not have the accuracy to put ExoMars in this deep hole.

The preponderance of slopes and boulder fields will be a consideration. And because ExoMars is a solar-powered rover, it will also be tied relatively close to the equator.

So where will ExoMars go? Favoured Locations that lost out for Curiosity's attention are sure to crop up again.

Mawrth Vallis Mawrth Vallis is one of the oldest terrains on Mars and a favoured destination for many scientists

If I were to nominate an early runner in the race, it would probably be Mawrth Vallis.

This is a favourite among many European planetary scientists, and is the location where Esa's Mars Express Orbiter spied abundant deposits of magnesium-rich and iron-rich clay minerals - a clear sign that a lot of water was once in contact with the rocks over an extended period. To find evidence of life, you must follow the water.

Prof Dawn Sumner, who was co-chair of the Curiosity landing site working group, told me: "Mawrth Vallis is a site of exposed ancient martian crust - crust that is likely older than any rocks we've found on Earth.

"The rocks there show spectral signatures of diverse hydrous minerals in data from Mars Express and Nasa's Mars Reconnaissance Orbiter.

"These spectral signatures, within the oldest crust, make this site attractive, because it provides an opportunity to study the formation and alteration of some of the oldest parts of Mars.

"Mawrth Vallis, like most of the ancient martian crust, shows evidence of multiple impacts; it is the high concentration of impact craters that indicates that it is old.

"These areas show evidence of multiple fracturing events due to impacts, and the Mawrth Vallis landing ellipse identified as a Curiosity candidate shows many fracture patterns that may be related to various impact-forming events. The fracture patterns vary in the area and may be part of the landing site selection considerations."

Control room The operations room at Harwell: Learning how to run a Mars surface mission starts here

Wherever ExoMars goes, it will be given an initial mission lasting 218 martian days, or sols.

It will get rolling quickly to make the most of the opportunity, and in this past week some of those who'll be involved have been getting a feel for what surface operations will involve.

Bridget in the Desert The Chilean desert is remarkably Mars-like

A dummy control room has been set up at the Satellite Applications Catapult in Harwell, Oxfordshire, from where instrument teams have been sending commands to a prototype rover in the Atacama Desert.

The boulder fields of this Chilean landscape look just like Mars, and it is cold and dry to boot.

Twice a day, the Harwell team has been examining pictures acquired by the prototype, known as "Bridget", and then directing it to various targets to investigate.

The commands are sent to the "relay orbiter" (in reality, a support team in the desert), where they are checked and uploaded into the rover. Bridget does its stuff, examining rocks with its "hand lens" and imaging the sub-surface with radar, before returning the data to England to repeat the exploration cycle.

"Operations is a very different discipline from design and testing; and you have to get people into a different mind-set," says Lester Waugh from Astrium, the big European space company that is leading the manufacture of the ExoMars rover.

"You think very much about risk, because if there is any danger that the rover may be damaged, you have to think very seriously before doing something - because you could lose your mission."

Jonathan Amos Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this

    Comment number 29.

    empiredown : there is no appetite by the 1% elite that have hoarded most of the planet's wealth to solve the problems of the poor. Right now the US government cannot afford to support any federal projects because a few far-right i.e. "Republican" Merkins do not want to part with any of the wealth they have stolen to help their less fortunate countrymen. Our own Tories are destroying Welfare...TBC

  • rate this

    Comment number 28.

    I expect those fleeing Cyclone Phailin, hungry though they might be, are grateful of the early warning, and appreciate science does a better job at predicting such events than some guy consulting the entrails of a sacrificed goat or a frond of dried seaweed. Spending all you dosh on feeding people isn't a good idea, especially if they are drowning.

  • rate this

    Comment number 27.

    I do not understand those who claim money spent on science is wasted. How do they think ALL modern technology came about?

    We have thrown money at all the problems on Earth and they have not gone away. So I see no problem in spending an essentially irrelevant amount of money on space.

    In fact I think we should spend more as returns to the economy of space research is often extremely high!

  • rate this

    Comment number 26.

    Wherever it is you can be certain that islamists will declare it independent and seek to banish everyone else.

  • rate this

    Comment number 25.

    Could understand experiments in space involving geo-engineering technologies which might be applied to stalling catastrophic climate change but spending limited monies on Mars is plain and simple dumb. You are running out of time to make the correct choices.

  • rate this

    Comment number 24.

    12. TheShadow -Science and technology spending is always money well spent, we have many things today thanks to research, discovery and development. How can we spend 200 million on Bombing Libya yet refuse to fund science projects? Its been a good week for funding science with the billion pound brain project and the discovery of a drug that may help Dementia sufferers.

  • rate this

    Comment number 23.

    Shame that no probe or rover would survive near the poles, as the carbon dioxide geysers would be a spectacular sight.
    Would also like to see a mission to one of those mysterious water flows, to test if there is still liquid water flowing on Mars. That would be an amazing discovery & validate findings from various other rovers, probes & satellites.

  • rate this

    Comment number 22.

    Don't give me the 'there's no spin off' mantra. Because thats not thinking at all. There's too many 'can't see beyond the end of their nose', but noisy commentators on science and development. All of your luxuries and home comforts came about because someone researched them. There are a HUGE number of things out there that are ONLY there because of space research and (yes) military research too.

  • rate this

    Comment number 21.

    Mars is always going to be there. Send probes in a hundred years after we've figured out some fairly pressing issues here on this world? Nice to look at the stars and planets but they can wait. Don't give me the spin off mantra because I'll send it back with a dollar bill....there's your spin off from hubris and half thinking.

  • rate this

    Comment number 20.

    If you think money spent on space exploration is to high then you're ignorant to the truth. Since its creation NASA has only ever spent a fraction of the cost of the US military budget for one year, adjusted for inflation.

    The UK should invest in something worthwhile like this, it's far better for our planet than war. (war, NOT defense, just covering my back)

  • Comment number 19.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • rate this

    Comment number 18.

    It's science like this, which includes Hydroponics, that is actually going to SAVE the poor and hungry of this world in decades and centuries to come. Research on how to feed long distance travellers to Mars and elsewhere will also be utilised here on Earth to develop ways of growing food in harsh climates. Give a man a fish and he'll feed himself for a day, teach him to use a rod...

  • rate this

    Comment number 17.

    This isn't science, it's the ESA trying to justify its continued existence, much the same way NASA "surprisingly" discovers something every now and then to remind us they're still needed.

    The only good thing I can say is at least they're not wasting even more money on trying to send people to Mars.

  • rate this

    Comment number 16.

    why on mars have an HYS on this, the chances of anyone, even scientists, being able to contribute on the actual topic & vaguely sensible is pretty remote

  • Comment number 15.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • rate this

    Comment number 14.

    See the money wasting science freaks are out in force today voting down feeding the hungry and voting up their red planet ego trips. What's wrong with our education system is well on display here. No values, no morals only nihilism and press the red button mate.

  • rate this

    Comment number 13.

    I understand there is very good skiing on the slopes of Olympus Mons and there is a good McDonalds and KFC.

  • rate this

    Comment number 12.

    Can we please spend money more wisely?

    There are millions of poor people in the world who need help, yet here we are giving scientists huge budgets to squander on pointless activities as this


  • rate this

    Comment number 11.


    You are absolutely correct. Neither politicians, and our plastic celebrity culture, understand or appreciate science and engineering. It's not a vote winner or throw-away trendy enough

    Perhaps when a landing site is found we could sent them all to Mars. Would make life much less monotonous back here

  • rate this

    Comment number 10.

    lets hope this european project is a bit more succesfull than that other european project.


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