Mars Express Has Given Us Some of Our Best Science on the Red Planet

The European Space Agency’s Mars Express orbiter has been observing the red planet since 2004, and continues to function today, more than four years after the scheduled end of its lifetime. During that time, it has sent back some of our most spectacular pictures of Mars to date and gained a huge body of data, including evidence of frozen water beneath the Martian surface and tantalizing hints of life. Mars Express is a triumph for the ESA, re-emphasizing that organization’s place as a major participant in the exploration of the solar system.

Mars Express was launched from Baikonur, Kazakhstan on June 2, 2003 on board a Russian Soyuz/Fregate launcher. The launcher provided all of the thrust needed to put the spacecraft on an orbit that would take it to Mars. The craft would only use its onboard propulsion system for minor course corrections, and to slow down for orbital insertion upon arrival at Mars.

Mars Express took about six months to complete its journey, arriving at Mars in December of 2003. Immediately before insertion into orbit around Mars, the probe was supposed to deploy a small rover which would land on the surface and perform close-up observations of surface features. Unfortunately, this was the only disappointment of the mission. The rover was supposed to send a signal to mission control on Earth confirming successful deployment, but the signal never came. After unsuccessful attempts to re-establish contact, the ESA finally had to face the reality: their rover was lost.

But there have been few space missions that have not had some minor malfunction, or some part that did not perform as planned. These failures are disappointing, but the overall merit of the mission should be judged by its successes, not its failures. For Mars Express, the successes have been stunning.

Mars Express (so called because it was made and launched with record speed, using parts and facilities from previous missions) isn’t much to look at. It’s a plain box, 1.5 x 1.8 x 1.4 meters large, with a small dish antenna on one side and two solar panels, which were deployed immediately after its detachment from the launcher. Though Mars is farther from the sun than Earth, and the solar radiation is correspondingly weaker, these solar panels are still capable of delivering 500 watts of electricity, which is enough to run the probe. When Mars is between the probe and the sun, a lithium-ion battery, charged when the probe was in the sunlight, takes over the power requirements. Mars Express contains seven scientific instruments contributed by Sweden, Germany, Italy, England and France. Besides the ESA member nations, the U.S. and Poland are also involved in the project.

When Mars Express was launched in 2003, everyone involved undoubtedly had a moment of deja vu remembering the ESA’s earlier attempt to launch a Mars probe. In November of 1997, the Mars 96 probe was launched, only to end up at the bottom of the Pacific Ocean when its second booster stage failed to propel it into a stable orbit. Mars Express was ESA’s attempt at a “faster, better, cheaper” mission, using nearly 80% of the design and components from the earlier Rosetta spacecraft and elements of the solar array taken from the Globalstar satellite series. Several of the scientific instruments on Mars Express are spares or modified designs of experiments lost on the ill-fated Mars 96 mission.

Part of the mission’s objective was to compile a series of photos which would make up the first 3D image of the Martian surface. In pursuit of this goal, Mars Express has taken pictures of landforms all over the planet, which, in addition to the scientific information that they can yield, are also stunningly beautiful. Analysis of these images will go on for years to come, and will undoubtedly reveal much about the planet and how its various features formed.

This mission has already yielded at least two pieces of information which, if confirmed by future investigation, have enormous implications in our understanding of the red planet. One is the possible presence of large amounts of frozen water beneath the Martian surface, and the other is the presence of methane gas, which could have been created by living organisms.

Let’s be clear about this. We’re talking about water, and maybe even life, which are present on Mars now, not in the distant past. For some years, there has been growing evidence for large amounts of water in the early days of planet Mars. Landforms show unequivocal signs of erosion from flowing water, including extensive river systems, deltas, etc. But all of that was long ago, when the atmosphere was denser and liquid water could form. At present, the atmosphere of Mars is so thin, water would sublimate directly from ice into water vapor without passing through a liquid phase. It was assumed that as the air got thinner, the surface water had turned into vapor and eventually been lost into space.

Maybe not. Mars Express has raised the possibility that a significant percentage of this ancient water is still there, beneath the Martian surface. In 2005, the probe found evidence for a large mass of pack ice just under the ground in an area close to the Martian equator. This ice, scientists theorize, may have collected in the geologically recent past, perhaps two to five million years ago, when flooding brought it down from the nearby Elysium region. The intervening land clearly shows the signs of this flooding. Planetary scientists theorize that the ice may be prevented from sublimating by a layer of volcanic ash which covers it.

The hugeness of this possibility cannot be overstated. Without native water, permanent colonies on Mars will be impossible. With it, our descendants can become Martians. That’s how big it is.

But there may already be Martians- at least small ones. Mars Express has found spectrographic evidence of methane in the Martian atmosphere above the same region where the water was detected. Methane can be made by inorganic processes- but on Earth, more than 90% of the methane was made by the activity of living organisms. And since methane breaks down when exposed to solar radiation, it only has a lifetime of 300 to 600 years.

It should be stressed that the methane findings are controversial, and are not accepted by all planetary scientists. But if the methane is really there, it must have been made in the last few centuries- and the most likely source is life. If it is confirmed by future observations, this could be our first incontrovertible evidence for life off the Earth.

This may be only the beginning for Mars Express. Its mission was supposed to end in 2005, but has now been extended through December of 2012. Considering what it has told us already, what else might Mars Express have in store for us?

As more information comes in, this site will feature updates. Watch for future articles.