NASA has given its next Mars rover a mission: seek out signs of past life, and collect rocks to send back to Earth 鈥� eventually.
Known for now as Mars 2020, the machine will be a skeletal duplicate of the Curiosity rover that landed on Mars in August 2012. It will use the same chassis and 鈥渟ky crane鈥� landing system as Curiosity, and will even use some of the existing robot鈥檚 spare parts, saving time and money on design. The team estimate that the 2020 rover will cost about $1.5 billion 鈥� a billion less than Curiosity.
Having so much already in place freed up NASA to start thinking about what the 2020 rover should do. In a press conference today, the mission鈥檚 science definition team unveiled a report detailing the new rover鈥檚 goals, which includes searching for compounds such as organics that would indicate ancient life and collecting and storing rock samples for a future mission to bring back to Earth.
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The team says these goals are a natural extension of Curiosity鈥檚 objectives. Curiosity is not directly searching for life, past or present 鈥� its charge is to find evidence that Mars could once have supported life.
In March, Curiosity showed that the rover鈥檚 landing site, Gale crater, most likely had both running water and the chemicals necessary to make a cosy home for past microbes. It is now on its way to a 5-kilometre-high mountain called Mount Sharp, where layered sediments may reveal even more about the planet鈥檚 past habitability.
Core values
Now that we are confident at least some parts of the planet were once habitable, Mars 2020 can check if anything actually lived there, says , Rhode Island.
鈥淲e are not looking for the life that must have been there, because we don鈥檛 know the answer to that,鈥� Mustard said in the press briefing. 鈥淏ut had life been there and left a mark in the geologic record, we want to be able to seek those signs.鈥�
The 2020 rover will bring high-resolution mineralogy instruments to identify potential biosignatures in the rocks and soil. It will also bring a drill capable of taking core samples from rocks, rather than pulverising them as Curiosity does. Taking cores preserves the geological record in the sample, allowing scientists to place any signs of life in historical context.
Dirty cache
Those cores will be stored in a cache to be picked up at a later date, the first part of a long-awaited sample-return mission. In 2011, an expert panel rated sample-return a top priority in the once-per-decade review of potential missions. Many scientists argue that bringing a chunk of Mars back to Earth is the only way we will know for sure if it holds signs of life.
鈥淚f you have samples on Earth you can do sequential analysis, repeat analysis, analyses using technology that is not currently flight-qualified,鈥� Mustard said.
One challenge will be designing a system that will keep the cache pristine, John Grunsfeld, NASA鈥檚 associate administrator for science, said during the press briefing. Curiosity was supposed to have a cache for collected samples, but the plan was scrapped over concerns that the hockey-puck-shaped box used to store them would be open to the Martian elements and so the samples would degrade.
First things first
For now the proposed plans are light on details about how exactly the cache will get back to Earth. The agency is only committing to sending this rover and collecting and storing a cache 鈥� not figuring out how to bring it home, said Grunsfeld.
鈥淎 lot of considerations go in there, including planetary protection: how do we protect Earth from anything that might be on Mars?鈥� he said. 鈥淎ll of that is future work.鈥�
The 2020 mission also stops short of seeking creatures currently living on Mars. 鈥淭he feeling is that, from many points of view, the planet鈥檚 surface is currently quite inhospitable to life. To do an extant-life exploration drives you to parts of the planet that are difficult to access,鈥� Mustard said in justifying the decision. 鈥淭he best prospect to look for signs of life would be in the ancient geologic record.鈥�
Lindy Elkins-Tanton of the Carnegie Institution in Washington DC, says that in focusing on past life, the Mars 2020 rover will actually have a better chance of reaching its aims. 鈥淚f we were only looking for microbes on the surface right now, that鈥檚 a tiny snapshot of the history of life.鈥� By using rock samples to look further back in time, she says, 鈥渨e鈥檙e basically integrating over time and maximising our chances of getting results鈥�.
