Although as you can imagine, adds Bass, there is a little more to it than that. “If we just go to a random location on Mars and started tossing things into a coffee cup, it’s unlikely we would find what we are looking for.”
Plans for a sample return mission are still on the drawing board but most envisage a spacecraft landing a rover (or even several small rovers) in an area where life might have hung out. Probably a place where there used to be flowing water. Once safely on the ground, the rover will trundle off to collect soil or rock from a number of key sites, digging or drilling into the Martian dirt. It will then return to the lander to load its samples into a coffee-cup-sized capsule. So far, so straightforward – and certainly achievable with existing robotic technology.
The most crucial part of the mission, the sample return stage, is a lot harder. Nasa’s current concept employs a rocket – built into the lander – to launch the capsule from the Martian surface into Mars orbit. Here, it docks with a mothership. This spacecraft then fires its engines and heads back towards Earth. As the sample return spacecraft approaches our planet, it will use parachutes to survive a 50,000 km/s (30,000 mph) plummet and descend gently to the ground (or sea) for recovery.
Mission planners are well aware that docking with a spacecraft while in orbit around another planet has never been attempted before nor has bringing that spacecraft back to Earth. But assuming all goes to plan, the idea is that the samples will be recovered from the capsule and whisked away into a “secure containment facility.”
The technology being looked at for this laboratory is based on existing secure biological or nuclear facilities, incorporating the lessons learnt from Apollo. The aim of quarantine is not only to prevent any risk from Mars germs – and some horrible Andromeda Strain scenario – but the contamination of Mars samples by Earth microbes. Although the chances of the sample containing a deadly bug are almost certainly miniscule, the consequences of any release are potentially serious. What if there really was a deadly bug on Mars? However remote the possibility, we would be foolhardy to rule it out. It is therefore essential that, unlike the Stardust mission, the container survives its return.
The mission’s success is also vital for Nasa’s plans beyond sample return: a human mission to Mars, currently slated for 2033.
“Mars sample return has a second very important purpose: to demonstrate a rocket that can leave Mars,” Beaty explains. “If you can’t demonstrate you can return a rock from Mars, how can you believe you can return a human?