A mechanical foul-up on one of NASA’s two Mars rovers has led to the serendipitous discovery that water once existed in the Gusev crater, which lies 15 degrees south of the Martian equator. Although the consensus is that Mars was in the distant past a watery place, there is little evidence of water present today anywhere other than at the frozen south pole. The latest discovery raises hopes that water will be found beneath the surface at lower latitudes.
While roaming around inside the Gusev crater, the rover Spirit suffered a stuck wheel that now drags as the vehicle moves along, churning up soil as it goes. By accident rather than design, Spirit has an effective trenching tool, and the onboard thermal emission spectrometer is able to measure the composition of soil exposed by the wheel.
A bright patch of soil exposed by the new tool produced a strong signal of silica, which, according to our current understanding of geochemistry, was most likely formed by one of two processes, both of which involve water in large amounts. NASA scientists say that either water saturated with silica and heated by subsurface seismic activity percolated up through the soil and evaporated, or highly acidic steam from a volcano eruption rained down, leaching away everything except silica.
I find it difficult to keep up with all the stuff coming out of the Mars Exploration Rover Mission, and am amazed that the rovers are still going strong. No-one expected the mission to last this long.
Meanwhile, the European Space Agency’s plans to send a robotic rover to Mars faces a critical review this week. An ESA Council meeting in Paris will finalise a design concept, and decide whether the plans are affordable. The design for ExoMars currently under consideration by Council delegates is much more expensive than the €650m originally budgeted. A decision is expected on Thursday.
See here for details of ESA’s current and highly successful Mars Express mission.