A small motorised contraption, the size of a golf cart, has been trundling across the Martian desert for the last seven years. It may no longer capture the news headlines as it did shortly after it first bounced onto the red planet in January 2004, but it is an extraordinarily successful mission that has far exceeded the expectations of NASA, who had planned for a 90-day lifetime. It’s a project I’ve followed avidly since it arrived. A couple of weeks ago, it reached the edge of the 14-mile wide crater Endeavour, and has begun a new science investigation that could last several years.
Prior to 2004, Mars had been the graveyard of space science missions – the most recent being the ill-fated British Beagle 2 expedition. Nevertheless, NASA had optimistically planned to land two rovers which would explore the terrain and begin looking for signs of water in the planet’s geological history. The first landed in the giant Gusev Crater; the second, named Opportunity, arrived on a plateau on the opposite side of the planet. They used an innovative landing technique, inflating giant airbags that bounced onto the surface before deflating and unfurling, allowing the rovers to roll off.
Opportunity scored a bull’s-eye when it landed, as it rolled into the middle of a small crater. This meant that it could immediately start exploring the exposed rock in its environment without travelling far. Before long, NASA focussed on some small, blueberry-sized spherules. They found that these were rich in the iron-based chemical, haematite. On Earth, they are rare, but are found in desert conditions where there is evaporating water. It was the first and most dramatic confirmation that water had once existed on Mars, and paves the way for future expeditions that could explore the possibility that life might once have existed there, too.
During these initial three months, dust gradually accumulated on the solar panels, which was expected to block out the Sun’s radiation. However, after a while it became apparent that some of the dust would disappear – perhaps being blown off by winds in the thin Martian atmosphere – and the possibility of a longer expedition arose. Thus, a rover designed to travel half a mile began to range far beyond its expected capabilities.
Two and a half years later, it arrived at the half-mile wide Victoria crater, without doubt its most spectacular destination, where it remained for another two years. The aim was to be able to probe the geology of the area at far deeper levels than ever before.
It has not been without alarms. On one occasion it was stuck on the side of a crater, on a slope that was almost too steep for its wheels. Then later it became trapped in a sand dune for several weeks before some clever routines enabled it to inch slowly out.
Nevertheless, the rover that was planned to drive half a mile in ninety days has now completed 20 miles in seven and a half years, an extraordinary accomplishment that will enable NASA to plan much more ambitious follow-up missions. As it sits on the edge of Endurance crater, NASA scientists can now plan geological projects in the years ahead, which would never have been thought possible when this golf buggy first arrived on the planet.
Check out this video of the journey to Endeavour Crater.