Nasa’s Mars Curiosity rover has completed a Martian year – 687 Earth days – on the red planet having accomplished its main goal.
The rover successfully landed on in the Gale Crater on August 6, 2012, with the mission of determining whether Mars once offered environmental conditions favourable for microbial life.
The answer was a historic ‘yes’ after two mudstone slabs found at an area known as Yellowknife Bay that the rover sampled with its drill revealed the site was once a lakebed with mild water, the essential elemental ingredients for life, and a type of chemical energy source used by some microbes on Earth.
Despite this early success the rover has not been entirely lucky after wheel damage late in 2013 prompted a slow-down in driving as the mission team adjusted routes and driving methods to reduce the rate of damage.
But the team is ahead of schedule, as they had expected the rover would have to reach the lower slope of an area called Mount Sharp before meeting the central goal of the mission, and while they will need to continually adapt to the threats the terrain poses to the rover's wheels it is not expected to be a determining factor in the length of Curiosity's operational life.
"We are getting in some long drives using what we have learned," said Jim Erickson, Curiosity project manager at Nasa's Jet Propulsion Laboratory in Pasadena, California. "When you're exploring another planet, you expect surprises. The sharp, embedded rocks were a bad surprise. Yellowknife Bay was a good surprise."
Curiosity paused in driving this spring to drill and collect a sample from a sandstone site called Windjana and the rover currently is carrying some of the rock-powder sample collected at the site for follow-up analysis.
It departed Windjana in mid-May and is advancing westward towards Mount Sharp, having covered about nine-tenths of a mile (1.5km) in 23 driving days and brought the mission's odometer tally up to 4.9 miles.
The findings so far have raised the bar for the work ahead and at Mount Sharp, the mission team will seek evidence not only of habitability, but also of how environments evolved and what conditions favoured preservation of clues to whether life existed there.
The entry gate to the mountain is a gap in a band of dunes edging the mountain's northern flank that is approximately 2.4 miles ahead of the rover's current location and the new path will take Curiosity across sandy patches as well as rockier ground.
Terrain mapping with use of imaging from Nasa's Mars Reconnaissance Orbiter will enable the team to chart safer, though longer, routes.