As Nasa’s new probe lifts off for the red planet, an Imperial scientist prepares to analyse individual grains of Martian dust…and maybe micro-organisms.
Matt Brown
If all goes well, the Phoenix Mars lander will blast off from Cape Canaveral this weekend, beginning its ten month voyage to our neighbouring planet. After landing in the Vastitas Borealis region in the northern latitudes, it will scoop up and examine the icy soil in unprecedented detail.
The probe’s science team is international, and includes a group from Imperial College headed by Dr Tom Pike. His team created the micromachined silicon substrates for the lander’s microscope station. The substrate will hold soil samples for analysis by an optical microscope and atomic force microscope (AFM).
Just days before the launch, Nature Network London asks Dr Pike about his hopes for the mission, and the possibilities of finding life.
My Science
What information do you hope to gather by analysing Martian soil optically and by AFM?
We’ll be the first to be able to image the individual grains of Martian dust, which are right at the limit of optical resolution and need the AFM to get any detail. The surface finish of the grains may give us a clue as to the role of water in their formation. We should also get data as to how the grains bond together. But we also expect surprises – no one has looked at Mars at this resolution before.
How do these analytical capabilities compare with those of the recent rover missions?
We’ve got more than 100 times the resolution of their microscopic imagers, and with the AFM will get 3-D information.
How many soil samples can the lander theoretically analyse in its lifetime?
The microscope station has ten sets of substrates, but we can always reload on top of previous samples. We hope to analyse at least ten samples. For the other instruments on Phoenix, the wet chemistry laboratory can look at four and the thermal and evolved gas analyser (TEGA) can process six.
So if you hit jackpot, and there are micro-organisms in the samples, would you be able to distinguish between living and fossilized remains?
If life really is active in the samples we’re looking at, we would look for motion upwards or sideways on the substrates (not just settling under Martian gravity) by taking multiple exposures. We can do effectively time-lapse photography with the optical microscope and AFM. But it might be rather difficult to distinguish between microfossils and dormant spores. We’d be looking to have confirmation from the mass spectrometer of TEGA that there is organic material in the samples.
Phoenix is designed to last just 3 months. Is this a conservative estimate (viz. the Mars rovers’ continuing longevity), or is it certain to die once the Martian winter sets in?
It’s almost certain to die – as we’re so far north we lose the sun for good after the Martian summer.
My web
How is the web changing your field?
The first mass web event was the Pathfinder landing on Mars in 1997. The web has been an essential tool in getting out the results from space missions, both to the general public and amongst planetary scientists.
Which scientific websites do you visit most regularly?
New Scientist, Nature, and the science sections of UK newspapers and the BBC.
Do you ever read scientific blogs? If so, which ones?
Ben Goldacre’s Bad Science. Oliver Morton’s Mainly Martian is great but I wish he’d update it more.
My London
Why did you choose to work at Imperial?
In 2001 the first chance to fly the microscope station on Mars Surveyor was cancelled. I was working at the Jet Propulsion Laboratory in Pasadena at the time. Shortly after a couple of people independently pointed out that Imperial were looking for new faculty. I had always envisaged coming back to the UK, and applied with some hesitation—I thought I’d be leaving the Mars microscope project behind.
Where in London would you celebrate getting a paper on the cover of Nature?
I’d hire a cabin on the London Eye—as well as enjoying the view it will serve as a momento mori that even if you’re lucky you’re only truly at the top of your field for a few moments and next week someone else will take over your spot.
Do you have a favourite of London’s 30 or so scientifically themed museums, or an exhibit that you find particularly striking?
I love exploring the nooks and crannies on the upper floors of the Science Museum. There are some of the classic scientific instruments on display in the quiet galleries up there.
What one thing would make London a better place for science?
Making the museums free was top of my list. Very parochially, the plan to finally unite the Museums, Colleges and Institutions of South Kensington into one pedestrianised plaza will produce a great focus for science in London.
Who would you nominate as the greatest scientist to have worked in London?
Dennis Gabor. When I first started my PhD I was fascinated by his work on electron holograms at Imperial for which he got the Nobel Prize. His 1948 Nature Paper A New Microscopic Principle is very brief but his proposals have kept scientists busy ever since. Now his bust is down the corridor from my office.
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