Touchdown confirmed: Curiosity arrives safely on Mars

Science and Technology
The Mars Science Laboratory is on a mission to determine if Mars is, or was ever, able to support microbial life/Science Photo Library

There were many relieved looks on the faces of scientists and engineers monitoring the delivery of NASA’s latest robotic explorer to Mars on August 6th 2012. The Mars Science Laboratory Curiosity is the latest stage in a protracted exploration of the red planet, which began shortly after the dawn of the space race in 1957. The rover takes up the mantle of its predecessors, Spirit and Opportunity (which landed in 2004) with the aim of gathering information about the geology, climate and potential habitability of Mars.

Shortly after 05:17 on August 6th, mission control announced that NASA’s youngest explorer had touched down safely at its intended target: the large and geologically complex Gale crater.

Curiosity is a six-wheeled, remote control science laboratory. Powered by a radioisotope thermoelectric generator and with a mass of almost 900kg, it is equipped with an impressive suite of instruments, some of which are mounted on a robotic arm. In addition to its 17 cameras, the rover sports a drill for boring into rocks of scientific interest, a microscope for examining them, and various spectrometers for determining their elemental composition. Furthermore, it has various instruments for detecting (among other things) water and near-surface radiation, a versatile onboard chemistry laboratory for in-situ chemical analysis of rock samples, and an instrument for studying the Martian weather.

The rover is connected to the descent stage by three nylon tethers and by an umbilical providing a power and communication connection. The bridle will extend to full length, about 25 feet (7.5 meters), as the descent stage continues descending. Seconds later, when touchdown is detected, the bridle is cut at the rover end, and the descent stage flies off to stay clear of the landing site./NASA

As might be expected, the hairiest part of the long flight from Earth was the descent onto the Martian surface. In previous missions, rovers have been encased within large clusters of airbags, and have literally bounced onto the surface, (following deceleration by a parachute) before finally rolling to rest. For this mission, NASA opted for a more ambitious landing mechanism: a slower, powered descent, using rockets attached to a “crane” from which the rover itself was gently lowered onto the surface.

During the descent, an onboard camera photographed the landing site, giving geologists their first close-up of the landscape which will be the focus of their studies for the next few years. Once on the ground, the health of the rover was scrutinised by mission control, and one by one, the instruments have been switched on. With these preliminary checks out of the way, Curiosity has started its exploration. The first colour mosaic of the landing site was released to an excited public on August 9th, and shows a boulder strewn plain, with the high mountains that constitute Gale crater’s walls looming in the distance.

Curiosity’s ultimate destination is the foot of Mount Sharp, the 5.5km peak rising above the centre of Gale crater. This will be a journey of roughly 7km as the crow flies, although the rover will make frequent stops to examine geological curiosities on the way. Gale crater is 154km in diameter and was selected by NASA scientists because it offers access to rocks which may record the former presence of liquid water on Mars.

All being well, the first drive is scheduled for Aug 21th, and will involve traversing a distance of just a few metres, so that the performance of the rover’s wheels and navigation software can be evaluated. With a top speed of 90m/hr, the rover is expected to cover lots of ground over the next few years of surface exploration. Opportunity, one of its predecessors, travelled almost 35km and is still operational, an astonishing 8 years after its arrival on Mars! Whether Curiosity survives this long depends on the skill and ingenuity of the engineers behind the wheel, who now have the exciting task of planning their trek across the sand dunes within Gale crater.

During a brief telephone conversation with mission control in California, Barack Obama jokingly requested that should they find evidence for life, they should “please let me know”. He went on reassure them that NASA would continue to receive funding for this and future missions.