Mars Express celebrates nearly 10 years orbiting the Red Planet
Sen—As Mars Express closes in on a decade at the Red Planet, the European Space Agency promoted a video in late October highlighting the wonder and strangeness of Mars.
The video shows topographic data gathered by Mars Express' High Resolution Stereo Camera, a multi-sensor instrument that gathers every image from three points: directly below, looking forward and looking backward. The stunning three-dimensional views were compiled into a video by German space agency DLR in June 2013, to mark the ten-year anniversary of Mars Express' launch, and then put on ESA's main YouTube video feed on October 28.
"From the highest volcano to the deepest canyon, from impact craters to ancient river beds and lava flows, this showcase of images from ESA's Mars Express takes you on an unforgettable journey across the Red Planet," ESA wrote in the text accompanying the video.
Although the images have artistic appeal, the root of their scientific work has revealed a planet -- previously believed to be dry -- as one that was shaped by a lot of water in the ancient past. Mars Express arrived at the planet on Dec. 25, 2003 and has helped immeasurably with that search.
The spacecraft's pictures revealed areas of the planet carved by gullies, presumably by a glut of water that rushed across the surface in the ancient past. Mars also could have had an ocean; in February 2012, results released from the spacecraft's MARSIS radar unveiled sediments "reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars," ESA stated at the time.
That's not to say that water isn't present today. Mars Express, in fact, was the first to confirm that water ice is at the Red Planet's south pole. The OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) instrument on board the spacecraft found huge tracts of permafrost where water, mixed with dirt, froze into a rock. This made the water hard to detect in visible wavelengths, but OMEGA spotted it using an infrared sensor.
OMEGA also spotted hydrated minerals, or minerals that formed in liquid water, across big but separated areas of the Martian surface. Hydrated sulphates, for example -- substances formed in acidic water -- were visible in Valles Marineris (the largest canyon in the solar system), in Terra Meridiani (the general area where the NASA rover Opportunity is) and also in dunes at the north pole.
"This pointed to periods of different environmental conditions in the history of the planet," ESA stated.
Why and how Mars changed, however, is still unknown. Also, not all of Mars Express' discoveries have been confirmed with other Red Planet missions. For example, in 2004 the Planetary Fourier Spectrometer on board the spacecraft detected the signature of methane in the Martian atmosphere. Follow-up observations from NASA's Curiosity rover in Gale Crater in 2013, however, revealed nothing. Further, the full story of water on Mars is not yet known; the ocean hypothesis, for example, is still being investigated by scientists.
The spacecraft has defied longevity expectations, far surpassing its initial one-year Martian mission (or two years on Earth). As the wealth of scientific results became apparent and ESA found the funds to do so, the agency extended the mission again and again. The latest extension has the spacecraft completing its mission in 2014, and the instruments on board are still working well.