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 129.

    @Chewbacca stole my Girlfriend 52
    He probably did her a favour. You obviously have a tenuous grip on the science. A 4x4 burning diesel in a mostly (and very thin) CO2 atmosphere (95%) is going to go nowhere. Of course at (mean temp -62°C) the fuel will be waxy sludge anyway. Don't give up your day job, engineering is obviously something you need to work on.

  • rate this

    Comment number 128.

    Interesting to see how anti expenditure on space science some on here are. I suspect that over a million Indians are pretty grateful for the research and investment that has led to the communications and weather satellites that enabled them to be evacuated before the latest Cyclone struck.

  • rate this

    Comment number 127.

    Uranus could be an option

  • rate this

    Comment number 126.

    Nili Fossae. There's really no good reason why a rover mission hasn't touched down there yet.

  • rate this

    Comment number 125.

    And the other thing about standing research is that it is often as likely to be built upon as it being rebuffed to find solutions. After all the so called great minds are called so because they shunned conventional wisdom.

    Sometimes the knowledge that we revere can be a true inhibitor to our development. So at the least we should never rule out alternative sources for inspiration and growth.

  • rate this

    Comment number 124.

    In deed politics does play a big role in resource allocation and policy direction. I suspect there is a form of elitism/protectionism in place. It prevents original solutions being sought.
    We are told man is remarkable and made so much from scratch, at the same time we are being channelled into a continuum, the risk being if we have taken a wrong turn somewhere there is no exit available.

  • rate this

    Comment number 123.

    #122 Two problems with that though.

    It looks a lot like the main difficulties of getting "food, health & education to all" are political, not financial

    The other is that research now is dependant on a lot of knowledge derived from previous research. If we don't do the research now will future generations have the tool available to solve the problems?

  • rate this

    Comment number 122.

    @117 Magnus
    I agree with you to an extent re:development, but to me the most valuable capital is human beings themselves "the most important resource on earth" as we discover how to utilise this planet, albeit we have made mistakes too.
    I would argue the best use of our money is to provide food, health & education to all the children in this world and having faith in them to solve our problems.

  • rate this

    Comment number 121.

    Considering the success of previous missions, landing on Mars could be a distinct possibility.

  • rate this

    Comment number 120.

    Where to land? Where we think Beagle II ended up - surely that the biggest mystery on Mars now that we know there's no life there?

  • rate this

    Comment number 119.

    118.OrdinaryWorld - " exotic propulsion systems need developing."

    It is all well & good saying it, but what if there is no better propulsion system than we already have...???

    There comes a point where man's ingenuity rubs up against the combined laws of physics/engineering (material properties) - we well have reached it already......

  • rate this

    Comment number 118.

    Yet more robots, the public are becoming bored of this now. It's dam near 2014 and man should of landed on mars a decade or more ago with the moon set up as a base soon after the apollo landings.

    The investment in new tech is well behind, there is only so far and so much a rocket and robot can do, new exotic propulsion systems need developing.

  • rate this

    Comment number 117.

    @106 Hamish Cameron

    Hamish, if our ancestors had stood looking at the world beyond Africa instead of setting out across it, who knows where we would be?

    Humans are curious, we like to find stuff out. And even if something seems useless today, it might be vital tomorrow. Having somewhere else to live in the Solar System is also sensible long-term.

  • rate this

    Comment number 116.


    How about spending a fraction of the costs (not mentioned here) to stop the human race from ******* up the planet we live on, maybe reverse the catastrophic damage already done to the environment on which we are all totally dependent.
    How should the money be spent so as to stop the human race from ******* up the planet?

  • rate this

    Comment number 115.

    Interesting. A lot of fun for the boys. How about spending a fraction of the costs (not mentioned here) to stop the human race from ******* up the planet we live on, maybe reverse the catastrophic damage already done to the environment on which we are all totally dependent.

  • rate this

    Comment number 114.

    there are almost as many rovers on mars that there are stories open for comment, actually no, there are more rovers on mars.

  • rate this

    Comment number 113.

    I don't understand why anyone would want to build tanks, guns, and missiles to kill other people when for a fraction of the cost we could put robots on other planets.

    Robots. On other planets. Surely that's a better legacy than a massive crater where there used to be a school.

  • rate this

    Comment number 112.

    Interesting to note the bickering about who is more competent to enact this project, the EU (Russian) side or the USA (NASA). I'm of the opinion that the better option is co-operation not competition would yield the best benefits to science. Has anybody mentioned either of the polar regions? these are my choices as nobody seems to consider these much. I am thinking of what can be found in the ice

  • rate this

    Comment number 111.

    How about landing here:

    [Unsuitable/Broken URL removed by Moderator]

    This is asuming, of course, that ExoMars is actually going to Mars, as opposed to being a prop on a film set -- like the "manned" Apollo moon landings were.

  • rate this

    Comment number 110.

    #109 AllenT2

    Hate to tell you this but the last time I looked NASA was so wreaked that they were having to use Russian Soyuz to deliver people to the ISS.
    NASA might have the tech but ultimately they have the huge handicap of being run by Senate committees and admins who often seem to have less competence than monkeys throwing their dung at each other.


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