managers hope to begin instrument procurement this fall for a $1.5 billion copy of the nuclear-powered Curiosity rover now exploring Gale Crater on Mars, with an eye to finding definitive evidence of whether the planet ever supported life, and whether its resources could support human life today.
Collecting rock cores for eventual return to Earth is also on the list of goals set by the science definition team thatestablished to begin planning the rover it hopes to send to Mars in 2020. The idea is to build on Curiosity’s engineering and discoveries to answer the priority question for planetary scientists — “are we alone” — while scouting for an eventual human mission to Mars.
“This rover will get us that next step — from was there a habitable environment, transitioning from planetary science to astrobiology, to ask ‘Do we see any evidence of past life in those habitable environments?’” says John Grunsfeld, associate administrator for NASA’s Science Mission Directorate.
Headed by Jack Mustard, professor of geological sciences at Brown University, the science definition team was charged with getting as much use as possible from Curiosity engineering models, designs and spare parts to advance the decadal priorities set out by the National Research Council. At the top of that list was returning samples from Mars to Earth, where the full panoply of laboratory gear — including some not yet developed — can be applied to finding evidence of past life.
Mustard’s team of experts in astrobiology, geophysics and geology, instrument development, science operations and mission design recommended an instrument suite designed to conduct “context” mineralogy and imaging, and move from that wide-view data down to “fine scale” elemental chemistry, mineralogy, imaging and organic detection and characterization.
Because the surface of Mars today is apparently toxic to life, the science definition team recommends landing in an area determined to have once been habitable and collecting subsurface core samples that leave the chemistry in context instead of grinding it to powder, as Curiosity does. Those cores — housed in a sealed container to protect Earth from possible contamination — would be retrieved and returned to Earth at an unspecified point in the future, by an unspecified technique.
William Gerstenmaier, associate administrator for human exploration and operations, has suggested a sample return vehicle might be intercepted by a human crew in lunar orbit and returned to Earth in an Orion crew capsule. Grunsfeld — a former space shuttle astronaut — says the sample cache might even be collected by a human crew on the ground, while stressing that no sample-return method has been selected.
Regardless of when and how the cache is returned, the instrument suite on the 2020 rover would be able to spot the most promising candidates for analysis on Earth. Jim Green, director of NASA’s planetary science division, says he and his colleagues will issue an announcement of opportunity as early as “late fall” seeking proposals for the instrument suite, which will cost $80-$100 million.
The rover itself is estimated to cost $1.5 billion plus launch, with recycled Curiosity elements allowing a reduction in that mission’s $2.5 billion price tag. While the two rovers will have many components in common, including the chassis and a radioisotope thermoelectric generator for power, the science definition team called for improvements in its landing precision, in part to develop the added precision that may be needed later on to retrieve the sample cache. Target selection would require another competition among promising sites, like those that determined where the twin Mars Exploration Rovers and Curiosity eventually set down.