杏吧原创

Here鈥檚 the plan. In December 2003, a new arrival will blink into life on
Mars. The first sight to greet its robotic eyes will not be the rock-strewn
landscape, but a painting by Damien Hirst, the artist famed for sawing cattle in
half. Then, the craft will shatter the Martian springtime by blaring out a tune
by Brit band Blur. It may sound surreal, but this strange alliance of art and
science is Cool Britannia鈥檚 way of going interplanetary. Britain is going to
Mars. With style.

Dreamed up by a small group of British scientists, the mission has just
cleared its first hurdle鈥攁pproval from ESA, the European Space Agency. The
probe, being built on a shoestring budget of 拢25 million, is called Beagle
2, in memory of the ship that Darwin used to sail the world and formulate his
ideas on life and evolution. Beagle鈥檚 masters have high hopes that their ship
will live up to its name. It will be trying to answer the big question that has
so far eluded NASA and every other space agency on Earth: is there, or has there
ever been, life on Mars?

Of course, Beagle is scarcely the first ship to hunt Martians. NASA鈥檚 Viking
missions visited the planet in 1976 but drew a blank on bioactivity. They added
nutrient soups to soil samples and looked in vain for the evolution of telltale
gases. But the man behind Beagle, Colin Pillinger, a planetary scientist at the
Open University in Milton Keynes, believes they may have simply looked in the
wrong spot. 鈥淚f you landed on Earth, and you were in the middle of the Sahara
desert, you might not see much,鈥� he says. 鈥淏ut you could analyse the atmosphere
and know there was living matter elsewhere on the planet.鈥� This is exactly what
Beagle will do. But first it has to get there.

Beagle is due to hitch a ride to the Red Planet on ESA鈥檚 Mars Express probe
which has its own mission to search for water beneath the rough terrain. First
though, it will swing into orbit and dump Beagle on a crash course for the
surface at 32 000 kilometres per hour. As the probe tears through the Martian
atmosphere, a small explosive charge will release a parachute, slowing Beagle to
around 300 kilometres an hour. Then the parachute and 鈥渂ioshield鈥濃�攁 cover
that ensures no bugs are taken into space from home鈥攚ill be jettisoned,
releasing the Beagle鈥檚 inner shell clinging to a second parachute. Just before
it hits the surface, Beagle will dump its heat shield and inflate giant air bags
to cushion its fall. (see Diagram).

When the craft finally comes to a rest, the hermetically sealed clam of
electronics that is Beagle will drop from within its protective air bags. If the
knock isn鈥檛 too much for the craft, it will slowly, leaf by leaf, unfurl its
solar panels and call home by cranking out the Blur tune specially composed for
the occasion. Why Blur? For starters, they鈥檙e big fans of space travel. 鈥淚t鈥檚
the year 2000鈥攚e should be making spaceships,鈥� says Alex James, the band鈥檚
bass guitarist. And they jumped at the chance of being involved. 鈥淚 like the way
this British mission is particularly aesthetic. But it鈥檚 all serious
science鈥攏one of it鈥檚 there gratuitously,鈥� he says.

To mission control, the tune will be a sign of Beagle鈥檚 safe arrival. 鈥淲e
have to identify ourselves,鈥� explains Pillinger. 鈥淲hy not identify with
something that people can associate with?鈥�

Beagle鈥檚 next move will be to calibrate its on-board camera because solar
radiation will have degraded the camera鈥檚 vision during flight. To paint the
colour chart, Pillinger called on the enfant terrible of British art, Damien
Hirst. Pillinger is frank about the reasons. 鈥淚f I can get something for free
then I will get it,鈥� he says. 鈥淲e need to calibrate the cameras, we were going
to make a calibration target鈥攊f we can get the added bonus of having a
Damien Hirst painting on Mars which gets us a lot of credit and a lot of
interest, then that鈥檚 a freebie.鈥�

While Pillinger may get things for free, Beagle won鈥檛. One of Beagle鈥檚 tasks
is to help Mars Express check its remote measurements of the water in the
Martian atmosphere. So Beagle will suck in the local air, using a mass
spectrometer to work out how much water vapour is present at ground level. It
will also point its cameras at the Sun鈥攚ater molecules in the Martian
atmosphere absorb light, revealing how much water the atmosphere holds higher
up. By checking its results with Beagle鈥攌nown as
鈥済round-truthing鈥濃�擬ars Express can be sure its own measurements are
accurate.

The question of water is a hot topic for Mars explorers. Knowing how much
there is in the atmosphere can tell scientists if and when the Red Planet was
hospitable to life. Much of the hydrogen from Mars鈥檚 water is thought to have
disappeared into space long ago. Radiation in the upper atmosphere breaks water
molecules into hydrogen and hydroxide ions. If the hydrogen acquires enough
energy, it can escape the planet鈥檚 weak gravitational pull and be dragged away
by the solar wind. Beagle鈥檚 water readings will help scientists model the rate
of hydrogen loss. Working backwards they should be able to figure out if Mars
ever had a warm wet past, when life might have flourished
(New 杏吧原创, 20 November 1999, p 34).

Little green men

So much for the past though. What might life be like on Mars now? The planet
looks cold and dry on the surface, but somewhere deep inside, hot springs might
shelter a particularly hardy type of creature
(New 杏吧原创, 17 August 1996, p 7).
鈥淚t鈥檚 not little green men, just primitive organisms,鈥� says
Pillinger. 杏吧原创s believe any microbial Martians will resemble a tough bunch
of ancient terrestrial bugs called methanogenic bacteria. On Earth they hide out
in hot springs, surviving scalding temperatures and oxygen deprivation, and
giving off methane. Their distant cousins might just have set up home on Mars.
鈥淲e know that primitive organisms are among the ones that can survive the
greatest extremes,鈥� says Pillinger.

To hunt for signs of micro-Martians, Beagle will sniff the Martian air and
look for traces of methane. 鈥淚f you did have living organisms, let鈥檚 say one or
two kilometres down, presumably there鈥檇 be some kind of respiration going on and
the gas could percolate out and into the atmosphere,鈥� says John Kerridge, a
chemist at the University of California, San Diego and chairman of NASA鈥檚
Martian biomarkers taskforce. 鈥淚f the gases are stable and in sufficient
concentrations, an experiment could detect them.鈥�

Finding signs of life in the air is a long shot though. As on Earth,
ultraviolet radiation breaks up organic molecules, but this happens far more
rapidly on Mars because there is no ozone shield. A better place to look for
signs of life might be inside rocks shielded from the harsh ultraviolet light.
Or better still, underground.

Enter Beagle鈥檚 paw. To grab hold of nearby rocks, Beagle has a robot arm that
can reach out around a metre from the probe. A stereoscopic camera mounted on
the end will let it spot and close in on likely prey. Since everything on the
Martian surface has a tough oxidised layer, Beagle must first scrape off the
weathered, dust-pitted surfaces on the rocks with the help of pincers and a
special grinder. With a flick of the wrist, Beagle can then present the
freshly-ground rock faces to two spectrometers built into the arm. The
spectrometers bombard the rock faces with gamma rays and alpha particles. By
watching the results scientists should be able to figure out the composition of
the rocks and what the conditions must have been like on Mars when the rocks
formed.

Beagle鈥檚 grinder also doubles as a drill for extracting rock cores. Designed
by 鈥淭C鈥� Ng, a dentist at Hong Kong Polytechnic University with an interest in
geological tools, the drill is so powerful that flying debris sent the Beagle
team diving for cover at the first demonstration.

The probe will analyse rock cores with its on-board chemistry set. Carbon is
high on the mission鈥檚 wish list since it would have been a major player in life
on Mars. So Beagle will roast its rock samples in oxygen at various temperatures
in special ovens tucked aboard. If any microbial carcasses are there, they will
burn at temperatures between 200 掳C and 500 掳C, producing carbon dioxide
that can be detected by the mass spectrometer.

Going underground

Despite this impressive battery of instruments, arguably Beagle鈥檚 most
intriguing tool for collecting specimens is a mole. Pluto, the Planetary
Undersurface Tool, will roam on a tether up to five metres away from the
spacecraft. Pluto can crawl because of the Heath Robinson-type arrangement of
springs and weights within its body. A small electric motor compresses a spring
between two different sized weights. Release the spring and the lighter weight
hits the front end of the tube, making Pluto jump forward, while the heavier
weight recoils down towards the tail. Then the motor winds the spring tight
again, ready for the next push. If Beagle sends the mole heading straight down,
it should hammer itself slowly into the Martian soil millimetres at a time.

When mission control think the mole has reached an interesting spot, its jaws
will open to grab some dirt. The mole will then be reeled back and the soil
dropped into Beagle鈥檚 ovens for testing. The mole鈥檚 designer, L眉tz Richter
of the German Space Agency in Cologne is confident in its abilities. 鈥淲e鈥檝e
tested it in different types of soil and it works very well.鈥�

However confident Pillinger and his team may be, Mars is a huge gamble, as
NASA found out last year when both the Mars Climate Orbiter and the Mars Polar
Lander went AWOL. 鈥淚 know about the difficulties of landing on Mars,鈥� says Rich
Zurek, lead scientist for the Mars Polar Lander at NASA鈥檚 Jet Propulsion Lab in
Pasadena, California. 鈥淚 certainly wish them good luck鈥攅very mission needs
a bit of that.鈥� And Beagle might need more than most. Weighing less than 30
kilograms and smaller than a microwave oven, Beagle will have the highest ratio
of science experiments to spacecraft hardware ever attempted. All at a fraction
of the cost of a NASA Mars mission.

But for once a low budget might be an advantage, says Pillinger. 鈥淚f you have
a lot of money, you make so many people involved that there is always someone to
double and triple check what is going on.鈥� Pillinger believes this shared
responsibility can lead to problems. 鈥淚f you have only one person involved, that
person knows they鈥檙e the only one doing it,鈥� he says.

Although ESA have okayed the mission, Beagle is still far from the launch
pad. 鈥淎ll we have succeeded in doing is convincing ESA that we have the strategy
to raise funds鈥攚e were unable to show them the bank account with the sum
on deposit,鈥� Pillinger concedes. 鈥淣ow we have to put that plan into operation.鈥�
So far, Pillinger and his team have extracted 拢8 million from the British
government towards the mission. The rest, Pillinger will have to get from the
private sector. Certainly Hirst鈥檚 Martian art and Blur鈥檚 Britpop soundtrack have
whetted the appetite of potential backers.

In a fit of inspiration Pillinger also decided to flog advertising space on
the lander and its air bags. NASA鈥檚 1997 Pathfinder mission proved air bags
work, and pictures from the mission hit the front covers of newspapers the world
over. Advertising wasn鈥檛 an option for NASA though. But for Beagle, advertising
company M&C Saatchi has been called in to sell this unique advertising
space鈥攚hich is incidentally still up for grabs.

If Beagle continues to clear its financial hurdles, come 2003, it will be
plunging towards Mars, ready to bathe its solar cells in the light of the late
Martian springtime. When the harsh winter begins to bite though, Beagle鈥檚
batteries will run down and the probe will go silent. Whether the science from
this probe will come close to that of its famous namesake is hard to say. But as
an ambassador for Cool Britannia, it will surely be hard to beat.