With abundant materials that can be harnessed by life.
Clear evidence of both flowing water and
a lake and some indication that this lake environment lasted for a long time.
It's hard to know exactly how long in the paper.
Grotzinger and his team tried to estimate it by saying, look, we don't really know
how long the mudstones take to build up, the mud takes to build up.
But if we make a gross estimate of how long that layer
of mud took to form, you come up with may be a couple of thousand years.
You could be wrong by factor of 10 or more in either direction but
certainly 100 years, now 100 years is not a very long time.
If you look from space, it looks like there's a lot more than just that tiny
amount that they were looking at in that tiny section there.
And they estimate that there could have been water flowing in these environments
for a million years.
Maybe not continuously, but at least sporadically.
Interestingly, this is early Hesperian time period, this is not Noachian.
We're used to the idea that there was water flowing in the Noachian.
We are less used to the idea that in the Hesperian, which is when we think of as
Mars drying out and forming these sulfuric acidic regions like Meridiani Planum.
We're not used to there being long periods of waterflow
like it looks like we had here.
Is this an unusual environment?
Perhaps, we certainly know that when we look globally
that it is true that the Hesperian is a time of drying out of the planet.
But in certain regions, it was clearly not happening very quickly.
All these findings lead to the conclusion which is
easily seen in the title of this paper.
A Habitable Fluvio-Lacustrine, fluvio means river, lacustrine means lake.
So it's the rivers going in a big lake region there.
Environment at Yellowknife Bay, Gale Crater, Mars.
Let's read the abstract of this and
see if we can understand what all these things mean.
Discovered fine-grained sedimentary rocks, this is the mudstone
that's a very important component of knowing that there was a lake there.
And it would have been suited to support a Martian biosphere founded on
chemolithoautotrophy.
Let's think of those words, chemo, chemical, that one we know.
Litho, rock, auto, self, trophy, growth.
Growth of microbes that are getting chemicals from rocks, which is enough for
them to grow.
Environment had a minimum duration of hundreds to tens of thousands of years,
possible duration of million years and
post-Noachian meaning during the Hesperian.
What does this tell us?
This tells us that Mars had a habitable environment in the past.
Maybe not all of Mars.
Maybe just small regions of Mars.
But if it had a habitable environment in the past it begs the very,
very obvious question, was it inhabited in the past?
Interestingly, the Curiosity Rover was not designed to answer that question.
It was very specifically only to answer the, was there a habitable environment?
People were felt burned by the Viking results.
When Viking results came back ambiguous or
negative, nobody wanted to talk about they're looking for life on Mars anymore.
But instead wanted to look for previously habitable environments.
This is a previously habitable environment.
And now, the conversation has changed.
Theres the obvious question that now really should be asked in this previously
habitable environment, was that environment inhabited?
How would you find out?
Well now, you would like to go back to this place or a place much like it and
start to look not just at the habitat but look for
evidence of organic molecules of the sorts that microbes build.
None of the instruments onboard Curiosity could do that very well.
And this is a big task of the next rover that's proposed to fly to Mars 2020.
Rover Mars 2020 is a duplicate of Curiosity, at least the rover part of it.
It's going to have brand new instruments on it though, that will presumably
specifically look for evidence of past life, not just past habitability.
It's a pretty exciting time in understanding habitability in
the universe when we have really demonstrated beyond a doubt,
I think it's fair to say that at least one other planet
in our solar system was absolutely habitable at some point in the past.
All these results that I was just telling you about came within the first
year of the mission of Curiosity.
You remember it landed here at this Bradbury landing site and all of that
stuff that we are talking about came from Yellowknife Bay in that first year.
Curiosity has now been on Mars for more than 1,600 Martian days.
This is an update from early 2017, and in that time it has gone nearly nine miles.
It went down to Yellowknife Bay and then went, traversed along here looking for
a spot where it can get into Mount Sharp.
Mount Sharp is off in this direction and
after a long time of traversing this way it finally has shot straight in.
Along the way there have been pretty exciting discoveries.
One of the most interesting ones to me is that although the muds at
Yellowknife Bay, and now that's been reproduced in many places in through here,
certainly looked like there was a lake,
it looked like it was a region that was habitable.
The one thing that has not been found anywhere along through here has
been evidence of carbonates, like for example calcium carbonates.
