“We’re on Mars again.” These simple yet astonishing words were spoken by NASA chief Charles Bolden as the Curiosity rover touched down on the Red Planet one year ago this week. The one tonne mechanical marvel had survived a nine month journey between worlds and then a perilous descent to the surface, lowered on cables from an innovative sky crane set-up on its spaceship.
Unlike 2004’s smaller Mars Exploration Rovers (MER), Spirit and Opportunity, the 2012 model was too heavy to land inside giant airbags, so mission engineers designed the tether system and a delivery rocket designed to fly off and crash-land a safe distance away. Nevertheless, the final approach to Mars was a harrowing experience for those watching as the touchdown system was something new, but necessary.
The safe landing was greeted with relief and jubilation by Bolden, Curiosity chief scientist John Grotzinger and the rest of the crew from NASA’s Jet Propulsion Lab (JPL). Their ingenuity was not just significant for this mission, but for future missions which may one day land a machine capable of returning Martian rock and soil samples to Earth.
In the twelve months since then, Curiosity has made several remarkable discoveries. From its base in the 150 kilometer-wide Gale Crater, the rover has confirmed the ancient presence of liquid water – a suspicion first recorded in 2010 by the Mars Reconaissance Orbiter – and has trundled through what appears to be a long-dry streambed. In February, a core sample was extracted from more than six centimetres inside a Martian rock, and JPL’s team was able to announce that a primary goal had been checked off just seven months into the rover’s planned two-year mission.
The following month, analysts announced that conditions on Mars were almost certainly habitable millions of years ago. In an area known as Yellowknife Bay, Curiosity had uncovered clear evidence of conditions fit for life. “We have found a habitable environment that is so benign and supportive of life that probably — if this water was around and you had been on the planet – you would have been able to drink it,” John Grotzinger said. Though there were no signs of John Carter’s “Barsoom”, Edgar Rice Burroughs’ fantastic Red Planet no longer seemed quite so fanciful.
Curiosity’s mission is far from over. The next step is a slow crawl to Mount Sharp, about five miles away, but as the rover’s cruising speed on hard, flat ground is only 0.09 mph it will take several months to get there. Scientists are hoping that they will be able to learn a great deal about ancient Martian history as Curiosity begins its slow ascent up the gently sloping mountain. At a height of roughly 800 meters, the mechanical marvel will cross a threshold which separates geological records of a wetter Mars from conditions experienced today.
Grotzinger is optimistic that Curiosity will continue to function perfectly on the long trip to its destination. “I think that this many-hundred-meter climb through the foothills of Mount Sharp could be just a great story in understanding the early environmental evolution of Mars,” he says. Although the Mount Sharp survey will take place towards the end of Curiosity’s lifespan, both Spirit and Opportunity continued to function much longer than expected and JPL specialists will be hoping that Curiosity’s plutonium radioisotope power system will remain reliable far beyond its original mission parameters.
So much has been achieved in the first twelve months of the Curiosity venture: proof that heavy machinery can be landed safely and precisely on another world; long-range mobility allowing for the collection of a wide range of samples; and irrefutable evidence of an ancient habitable environment. The exploration of Mars, which began in the 1970s with the Viking missions, will continue in 2020 when NASA launches another unmanned rover towards the Red Planet.