Rover moved 4.5m and rotated through 120 degrees, latest part of extensive health check-up since it landed on 5 August
After two weeks of checking instruments, testing software and practising its rock-zapping skills, Curiosity the Mars rover has taken its first baby steps across the surface of the red planet.
Nasa announced on Wednesday that Curiosity moved 4.5m, rotated through 120 degrees, then reversed 2.5m.
After a hair-raising entry on 5 August – when Curiosity was gingerly lowered to the surface by a module that fired rockets to keep the descent steady – extensive testing was needed to make sure all the caution involved in landing on Mars was not in vain.
"The first few weeks were set aside for the engineering team to get up to speed, to make sure all the systems and instruments check out OK," said Peter Grindrod, a planetary scientist at University College London, who has been watching every move of the mission. "They're not in any rush – this mission is meant to last for two Earth years. The first few days are about: is everything in one piece, are the cameras working?"
On Tuesday, Curiosity wiggled its front and back sets of wheels. Nasa engineers wanted to ensure all the steering actuators were still working, and that the wheel motors were turning. Every move was watched by the engineers via the rover's on-board cameras.
The engineers have also been upgrading software and getting used to using the robotic arm, which is 2m long and weighs in at 30kg – much bigger and trickier to manoeuvre than the arms on the previous Mars rovers, Spirit and Opportunity.
"There was a bit of getting used to using the arm under Martian gravity and calibrating the movements exactly, because they're going to deliver samples to these instruments on board, so they need to be very precise," said Grindrod.
The science experiments will start when the rover gets to its first place of interest, an area called Glenelg, about 400m away to the east of where it is now. Grindrod said Nasa will also probably have a good look at the blast marks created when the descent rockets moved away the dust during the landing. The landing uncovered what looks like interesting-looking bedrock.
The rover has already fired its laser into the landing site and taken pictures and data, but Nasa has not yet revealed any of the measurements. "All the other rocks on the surface look like the Mars everyone knows from Viking through to Spirit," said Grindrod. "The ones that have been revealed [at the blast marks] look like they might be slightly lighter toned and might suggest a different composition. The most interesting thing is that these don't look like rocks that are just sat on the surface and have ended up there, either from thrown out from a meteorite impact or having been delivered by erosion. These things look like they might be in situ, where they formed."
Geologists can use in-situ rocks to ascertain a good idea of the history of that part of the planet – when it formed, for example, and in what conditions.
It will take Curiosity around three weeks (or more) to travel to Glenelg and, along the way, Nasa scientists will be watching everything the rover sees, in case they spot anything interesting on the journey.
In the control room, the scientists work on Mars time. "They get all the images and data back for a Martian day and then, during the Martian night, that's when all the engineering and science teams are working to analyse the previous day's results and then plan the activities for the next day entirely and they are uplinked to the rover at the start of its day," says Grindrod.
It could be a year before Curiosity gets to its main mission: Mount Sharp.
"There's two main things that make Mount Sharp interesting. It's five kilometres of layered rock, which are probably sediments. We're not sure how they are laid down but, on Earth, those layers are very good at revealing the environment in which they formed."
The other thing that swayed it for Gale Crater as the landing site was the chemistry scientists saw from orbit. "Near the bottom there is evidence that water was around at some point in some form. If you go to the top, it's dry," said Grindrod.
Nasa's current Mars lander has barely started its operations, but they are already planning their next. Earlier in the week, the space agency announced that it would send a low-cost lander to Mars in 2016 to look deep into the red planet's interior.
The Insight project was chosen as part of Nasa's Discovery programme, and the mission won out against trips to a Saturn moon and a comet.
Insight will investigate how the interior of Mars is different to that of Earth – in particular, is it solid or liquid? A liquid core on Earth drives a dynamo that creates a magnetic field aruond our planet.
Mars does not have a magnetic field at the moment but scientists think it might have had one in its very early history.
As the core died out and stopped moving, said Grindrod, the planet would have lost its magnetic field and, consequently, its protection from the damaging solar wind. The atmosphere would have been stripped away, explaining why it is so thin at the moment.
"That happened at the same time as the volcanoes were erupting, that the water turned acidic," said Grindrod. "All these things happened at the same time, making Mars go from a mars-friendly environment to a more life-unfriendly environment, all at the same time."