After the failure of the Mars 96 mission, Russia must have felt “Mars Fatigue.” Virtually every mission the Russians had sent off to the Red Planet had met with failure, from outright launch failure to trajectories askew (missing the planet entirely) to landers that failed upon touchdown. In any case, their record could be seen as one of failure perfected.1
However, this is too simplistic. Much has been learned along the way, and one only need look at their successes with the hellhole that is Venus to see that the Soviet/Russian unmanned program has great merit. And, as the old Russian proverb says, “One beaten person is worth two unbeaten ones.”
It is perhaps in this spirit that the Russian Federation approached its cooperation with the European Space Agency's Mars Express mission. Launched in 2003 atop a Russian rocket, the mission included many components of its own failed Mars 96 project. In a bit of technological cross-pollination, some of the technology on Mars 96 had come from Western Europe, so this was not as much an admission of need on the Russian part as a chance for continued cooperation. In addition to the European Space Agency's role, NASA joined the effort, bringing expertise in tracking and control to the table.2
Mars Express derived its name in part due to the extremely short distance the spacecraft had to cover at that particular launch opportunity: in 2003, Mars and Earth were closer than they had been in sixty thousand years. It would not do to wait for the next one. It should be noted that at under $200 million (US), it was also one of the cheapest Mars missions on record.
The probe consisted of two major components: the Euro-Russian Mars Express Orbiter and the British Beagle 2 lander. The lander was a small and fairly simple craft, designed to assess the usual components of the Martian environment—weather, landing-site geology and geochemistry—and even search for indicators of life. Unique to this craft were its origins: rather than the usual government-industry collaboration, Beagle 2 was born in academia. A professor at the United Kingdom's Open University, in association with the University of Leicester, promoted the idea, eventually drawing in two other universities and four industry partners. The final result was a worthy craft, a small “clamshell” probe with a manipulator arm, designed to land via parachute and airbags, not unlike the Mars Pathfinder before it.
The successful orbiter followed traditional concepts, with a central body flanked by solar panels. The instruments onboard were designed to meet an increasingly familiar set of goals:
A spectrometer working in both visible and infrared wavelengths called OMEGA would determine surface mineral composition.
Another spectrometer in the ultraviolet and infrared wavelengths, called SPICAM, was specifically designed for sensing the composition of the atmosphere.
A radar altimeter called MARSIS would seek subsurface water.
A Fourier Spectrometer to measure atmospheric temperature and pressure.
A high-resolution stereo camera could photograph surface features.
And various radio and energy-sensing experiments were also onboard.
Mars Express was also equipped, as were Mars Odyssey and the Mars Reconnaissance Orbiter, to be a relay for NASA's other Mars landers and rovers.
As the craft neared Mars, the Beagle 2 separated to continue along its own path, bound for the planet's surface. It eventually made it, but not alive. So far as can be gleaned from the data, some part of the landing system failed and Beagle crashed.
The Mars Express orbiter was luckier, attaining orbit around the planet in late December 2003. This mission eschewed aero-braking; a small rocket engine was used for slowing and to allow orbital capture. As a result, the craft went into a highly elliptical orbit, 185 miles from the surface at its lowest point and 6,280 miles at its highest. Not ideal for orbital work, but far simpler (and safer) than pursuing a circular orbit.
Notable accomplishments of Mars Express are many. The poles were studied, resulting in a measurement of 15 percent water ice and 85 percent carbon dioxide there. Methane and ammonia were sensed in the atmosphere; this is noteworthy because neither would last very long in the Martian air, so a source of continual replenishment must exist. And that source could be active volcanoes, hydrothermal vents or…living things.3
Of course, water was again spotted, both as current ice deposits and as areas indicative of a wet past. Intensive atmospheric investigations were made, helping to identify the rate at which the air is thinning on Mars. Hydrated (water-altered) minerals were observed at the poles, and similar rocks were spotted in Valles Marineris, which continues to narrow down the time scale of the aqueous episodes of Mars. The idea of a wetter Mars in the distant past, followed by a drier, harsher planet in more recent epochs, as seen in the geological record, was strengthened. Auroral displays were observed above areas of strong magnetic activity. Finally, the lumpy gravitational field was observed and recorded.
The MARSIS instrument allowed for a more direct look beneath the surface of the planet, revealing yet more indications of subsurface water. MARSIS was further able to probe the intricacies of the polar caps, giving a better idea of the total mass of water ice there. The southern ice cap alone has a maximum depth of over two miles, and if melted, it could cover the entire globe to a depth of about thirty-five feet! Finally, a fascinating frozen mass of water was found in the Elysium region near the Martian equator—a place it really had no right to be. And it is young by geological standards—only about five million years old.
Not bad for a seemingly dry, dead world.
The mission of Mars Express has been extended numerous times and continues to this day. The probe returns a continuing stream of images and data from Mars and serves as a valued complement to NASA's own orbiters as well as an outpost of European scientific endeavors. Results from this mission have added greatly to the ever-growing knowledge of the Martian environment and its processes. In particular, the puzzling observations of stray methane in the Martian atmosphere have many researchers intrigued.
Europe and its partners will return to Mars with the ExoMars probe soon, possibly as early as 2016. With good planning and a dash of luck, some of these questions may be resolved.4