Dr Abigail Allwood, an Australian who is a leader on NASA's next Mars mission in 2020, said today's result is significant and raises big, exciting questions about whether life has ever been able to take hold on Mars, even if it isn't present today.
Here's what she has told Fairfax Media about today's discovery:
"This is a very significant result – it's the first clear evidence of liquid water at the surface of Mars, which fundamentally changes our view of the habitability of the planet today. It's also significant in terms of understanding possible resources for future human missions," she said in an email.
"The authors provided compelling evidence that the enigmatic "recurring slope lineae" (RSL) are associated with liquid water – an hypothesis that was unproven until now. The evidence? Hydrated perchlorate minerals associated spatially and temporally with the RSLs. The RSLs appear and disappear seasonally, and are temperature-dependent… an observation that's consistent with liquid water being involved (as opposed to e.g. purely gravity-driven processes). But the mineral observations are a major new piece of the puzzle. The authors propose that the liquid water is a perchlorate brine, explaining why the water is stable at martian surface temperature and pressure."
"What does this mean for the question of life on Mars today? Hmm, well… it makes it much more friendly for microbes than we previously thought. But the surface today is still in general a very inhospitable place. But the exciting thought to me is, if Mars even today is this favourable for life, then Mars through history must have offered innumerable opportunities for life to take hold. The question is, did it?
"We need to go and figure that out!"