Just before midnight at the Baikonur cosmodrome in Kazakhstan, Europe’s first mission to another planet should blast off aboard its Soyuz-Fregat rocket.
Mars Express, a cube just 1.5 metres on a side, carries the hopes of a generation of European scientists and engineers. The US space agency NASA has been a relatively frequent visitor to other planets and its teams can expect future missions. But for their European counterparts, the outcome of Mars Express is critical.
The aim of the mission is to find out what happened to the water scientists suspect washed over the surface of Mars and, perhaps, to find signs of the life that could once have inhabited those waters.
To do this, Mars Express will enter orbit and use a suite of instruments to scan the Red Planet from the top of its atmosphere to thousands of metres below the surface. Crucially, it will also deploy a British lander Beagle 2 with the key task of searching for organic signs of life. It has plenty of tools to work with, having the highest density of scientific instruments in any planetary lander yet built.
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Mars Express is the cheapest ever mission to Mars, costing about 300 million Euros ($350m). But ESA believes the low budget has not raised the risks of the mission, as the savings were made by using off-the-shelf technology and streamlining the bureaucracy. Nonetheless, history reveals the challenge presented by Mars – less than half the 30 missions to the planet have succeeded.
Double …
firing
Within a few minutes of launch (1745 GMT), the Soyuz rocket will be lost from sight and separate from the Fregat upper stage that carries Mars Express. A firing from the Fregat takes the craft into a circular Earth orbit. From here, 56 minutes later, a second firing will set the spacecraft on its 400 million kilometre journey to Mars.
The voyage will take six months, but 2003 is a good year to shoot for Mars. The planet is closer to Earth than at any time for 60,000 years. For this reason another three missions are due to arrive by January 2004.
The first critical test of Mars Express’s space mission will come on 19 December, when Beagle 2 must separate from its parent and coast down to the surface. “It will be a nail biting moment,” says David Southwood, ESA’s head of science, as if it does not happen, Mars Express cannot enter its required orbit.
The release mechanism, based on electrical heating of shape memory alloys and explosive charges, has been tested over 30 times, reassures the Open University’s Colin Pillinger, leader of the Beagle 2 team.
Frozen aquifers
Mars Express will take a highly elliptical orbit, and is aiming for at least two years of scientific work. Topographic and mineralogical mapping will be important, but perhaps most interesting will be the ground penetrating radar. This may reveal aquifers of frozen water as it probes up to 3000 metres below the surface.
The next crucial moment comes on Christmas Day when, six days after its release, Beagle 2 should touch down. It will have entered the Martian atmosphere at 19,000 km/h and used its heat shield to brake to about 1600 km/h. Then a newly designed parachute, claimed to be the most weight efficient ever made, will slow Beagle 2 to 65 km/h. It hits the surface at this speed, protected by gas-filled airbags.
As soon as it has landed and unpacked itself, Beagle 2 faces another stern test. It must start gathering solar power in order to survive its first frigid Martian night, with temperatures dropping to -70°C.
Beagle 2 is due to land at 0254 GMT, but will have to wait until NASA’s Mars Odyssey orbiter flies over before sending a signal home. That should arrive at an Australian receiving station at about 0500 GMT, and will be an as-yet-unheard nine note call sign composed by the British rock band Blur. Soon after will follow its first panoramic photo.
Dozen ovens
The target for Beagle 2 is a six month mission, analysing soil, rocks and the atmosphere. ESA scientists hope that combining this data with that from Mars Express will reveal where any water – crucial for life – remains and what happened to that which has been lost.
However, the instrument that has the biggest potential to excite scientists is the Gas Analysis Package (GAP). This has 12 tiny ovens in which samples will be combusted at increasingly high temperatures, with a mass spectrometer analysing each puff of vapour given off.
Isotopic analysis of the carbon could reveal the signature of previous life on the planet, as biological processes have a greater preference for carbon 12 than inorganic ones. GAP will also look for other gases, such as methane, which may indicate life. The 1976 Viking landers on Mars carried similar, but less sensitive, instruments.
Also, a burrowing probe called the mole will allow samples to be retrieved from up to 150 centimetres below the surface, away from life killing ultraviolet radiation. Pillinger notes: “Like the moles in your garden, the difficult thing is getting them out, but we have strategies for dealing with that.”
Low and flat
Beagle 2 will be exploring a tiny patch of the Isidis Planitia, a low, flat basin 10° north of the Martian equator. It was chosen to balance the scientific interest – there are some signs of the presence of water activity – with a safe place to land.
NASA has made similar judgements for their twin landers, due to leave Earth on 8 and 25 June. The missions to land these quad-sized rovers on Mars are costing $800m.
They have one key thing that Beagle 2 does not – wheels – meaning they will be able to travel up to 1000 metres away from the landing site. But they have no mole or gas analysis package.
Pillinger acknowledges his instrument-packed lander is more scientifically ambitious than the NASA landers, bringing greater risks. But NASA has a “different philosophy” to the UK-led Beagle 2 team, he says. They are working in an ongoing space exploration program – “we may never get another chance”.
New Scientist’s attendance at the launch of Mars Express and Beagle 2 was assisted by ESA and the spacecrafts¹ prime contractor Astrium.
