2017 August Evening Public Lecture — Roving on Mars

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Detailed Description

Roving on Mars: Curiosity's exploration of Gale Crater

* Overview of the Mars Science Laboratory Mission
* Highlights from 5 years of exploring sedimentary environments
* Preview of next steps in Curiosity's climb up Aeolis Mons

Details

Image Dimensions: 480 x 360

Date Taken:

Length: 01:09:29

Location Taken: Menlo Park, CA, US

Transcript

[ Silence ]

There we go.
Can everybody hear me?

All right.
Well, thank you all for coming.

Welcome to the USGS
evening public lecture series.

- Is the mic on?
- The mic’s not working.

- Not working? Hello?
- Better.

- Little better?
- Talk into it.

- Is that better?
- [many responses] Yes.

- There we go.
Okay, so my name is William Seelig.

I’m with Science Information Services.
Again, this is our August public lecture.

Before we introduce
tonight’s speaker,

just a reminder about
September’s lecture.

It’s – the title is, What’s in a Species
Name – How Wildlife Management

Relies on Modern Systematics
Research and Museum Collections.

It’s about the
Wildlife Research Center

at the Smithsonian Museum
in Washington, D.C.

So please grab a flier and
join us all at next month’s lecture.

Tonight’s title of our lecture is
Roving on Mars – Curiosity’s

Exploration of Gale Crater.
We have Lauren Edgar

from our astrogeology program
in Flagstaff, Arizona.

And just a little bit about Lauren.
So Lauren is a research geologist

at the Astrogeology Center.
She earned her bachelor’s degree from

Dartmouth College in 2007 and her
Ph.D. in geology from Caltech in 2013.

Prior to coming to the USGS,
she was a postdoctoral fellow

in the School of Earth and
Space Exploration at ASU.

She is an active member
of the Mars Science Laboratory

and the Mars Exploration
Rover science team.

Her research aims to understand
Martian surface processes through the

use of rover and orbital observations
as well as terrestrial field analogs.

She uses sedimentology, stratigraphy,
and geomorphology to infer

past processes involving water,
wind, ice, and volcanic activity

and to identify potentially
habitable environments on Mars.

So again, after the lecture – please hold
any questions until afterward.

There will be two mics at the back
where you can answer your –

ask your questions.
And please welcome Lauren.

[ Applause ]

- All right, well thank you all for
coming out. Hopefully you can hear me.

It’s a pleasure to be here tonight,
and I’m really excited to share with you

some of the results from NASA’s
Mars Science Laboratory

Curiosity rover mission
and our five years of exploring

diverse sedimentary
environments in Gale Crater.

So I’m a research geologist
at the Astrogeology Science

Center in Flagstaff.
And I also wanted to point out that

a lot of the work that I will show here
tonight would not be possible without

all of the science and engineering teams
that are part of the MSL mission.

So this will be a summary
of some of the exciting results.

And in this talk, I want to give a
brief overview of the mission so far –

kind of how we do operations,
where we went on Mars.

And then I’ll give a summary
of some of the distinct and

unique environments that
we have observed so far.

And then I’ll give a preview at the end
of kind of where we’re heading next.

So I always like to start with a
reminder of the primary scientific goal

for the MSL mission, which is to
explore and quantitatively assess

a local region on Mars’ surface as a
potential habitat for life, past or present.

So to do that, we want to characterize
the biological potential, the geology

and geochemistry, the role of water,
and the surface radiation environment.

So in my own work, I’m mostly
focused on looking at the geology and

geochemistry and what that can tell us
about the past role of water on Mars.

So to meet that goal, this is
Curiosity’s scientific payload.

So first of all, you can see
it’s a six-wheeled rover.

It stands about 2 meters tall,
and it’s powered on the backing

off the back of
the rover here.

You can see this radioisotope
thermoelectric generator.

So it’s basically – the heat
given off by plutonium decay

is what powers
the spacecraft.

So this is the part of the talk
where I get to say that I drive a

nuclear-powered laser-wielding
robot on Mars. [laughter]

But it actually has a pretty
powerful scientific payload,

and I’ll just give a brief overview
of what some of these instruments

are capable of and how
we use them in operations.

So you can see
on the rover’s mast

that we have a couple
instruments for remote sensing.

So we have our Mastcam – our Mastcam
imaging system, which consists of two

camera eyes that are capable of full-color
panoramic and stereoscopic imaging.

And I mentioned the stereo imaging
because we can actually use

the parallax between the two
camera eyes, and if we know

the angle to an outcrop or a feature of
interest, we can generate a range map.

So you can use those stereo images,
and then in – every pixel in that image

will have X, Y, and Z values.
So if you wanted to look at a

geologic contact and look at some
structural relationships, you’d be able to

kind of, you know, plot pixels, you know,
pull those out along a surface,

fit a plane to it, and that’s how we
actually take a strike and dip on Mars.

So you don’t – you’re not
a geologist there on the surface

with your Brunton compass.
We have to rely on the stereo imaging.

We also have the
ChemCam instrument,

which uses laser-induced breakdown
spectroscopy to get the elemental

composition of rock and soil targets up
to about 5 meters away from the rover.

This instrument also contains a camera
called the Remote Micro-Imager,

which was initially intended
just to provide context for

all of those little laser shot points,
but it’s actually one of our

more powerful cameras
that we have on board.

So more recently, we’ve been using it
to get detailed grain size and

textural information and to look at
targets that are much further away.

Then we have the
RAD instrument, which looks at

the surface radiation environment.
And this was actually the

first instrument that was
turned on on the mission.

So right after launch, kind of in that
cruise phase from Earth to Mars,

RAD was collecting data to characterize
how much radiation you might receive.

So this is very relevant for future
astronauts going to Mars,

characterizing how much radiation
they would receive in transit.

And also, it’s been operating
continuously on the surface.

And then, on the rover’s arm, we have
several instruments for in situ analyses.

So in order to get at the
bulk chemistry of a sample,

we have our alpha particle
x-ray spectrometer, or APXS.

We also have the Mars
hand lens imager, or MAHLI.

And this acts at as
a geologist hand lens.

So it’s a camera at the end
of the arm that you can get

really close to the surface,
just a couple centimeters’ standoff.

And this provides all that nice,
detailed grain-size information.

Then we have several instruments
that help us acquire samples.

So we have a drill.
You can see these prongs that are

sticking off of the end of the arm there.
We also have a scoop, brush, and sieves.

And these all help us acquire a sample
and then pass kind of the finer-grained

portion of that into some of the
instruments in the interior of the rover.

On the belly of the rover,
we have the MARDI camera.

So this is the Mars Descent Imager
that was initially planned to be used

just during landing.
But because we have a camera

underneath the rover,
we’ve actually been using that

to help characterize the terrain
beneath us as we’ve been driving.

And then, in the interior of the rover,
we have the CheMin instrument

that uses x-ray diffraction to
get at the minerology of a sample.

And then the SAM instrument,
which is a suite of mass spectrometers

that tells us about
chemistry and isotopes.

And then, on the back of the rover,
we have the Dynamic Albedo of Neutrons,

or DAN, instrument, which is used to
characterize subsurface hydrogen.

And then, also located on the
rover’s mast, there are a couple

little booms that stick off, and this is
our weather station, basically.

So it’s the Rover Environmental
Monitoring System.

And this tell us about temperature,
pressure, relative humidity, winds –

in a number of
different environments.

In my own research, I’m mostly
working with data from the MAHLI,

APXS, ChemCam,
and Mastcam instruments

to characterize past
sedimentary environments.

All right, and I also
wanted to touch on the

USGS involvement
in rover operations.

So in Flagstaff, we have about
half a dozen folks that are involved in

the daily operations of both the Curiosity
rover and the Opportunity rover.

So we’re involved in both the
uplink of commands to

some of the instruments
and the downlink of data,

making sure that we got all of
the products that we needed.

But I always get questions –
what is like to work rover operations?

Because I think this is perhaps
what a lot of people might think

rover operations looks like.
[laughter]

Perhaps you – you know,
you’re imagining that you’re

there with a joystick saying,
drive right, drive left.

Or maybe you think you’re Matt Damon
roving around on the surface.

But in reality, this is what rover
operations actually looks like. [laughter]

So we work a lot of
with Gantt charts.

So here you’re just looking at the
timeline from left to right, and then how

we can actually fit all of these different
observations that we want into a plan.

Don’t worry about reading the
details here, but the different-colored

blocks just show how we have
time that’s devoted for science

and time that’s devoted to
other activities, like mobility.

Kind of that blue – royal blue box
that you see is a science block,

and within that, we have several
ChemCam observations that are nested.

And we really need to try and fit all
those science observations in against our

time, power, data volume constraints,
as well as telecommunications passes.

So the green boxes that you see represent
when we have orbiters.

So we have satellites
in orbit around Mars

that are helping to relay
data back and forth.

So early on in the mission, this is
what rover operations looked like.

This was when the whole team
was together at JPL living on Mars time

for the first three
months of the mission.

So to really maximize the science return
from that initial phase, we had everyone

living on Mars time, which is about
half an hour longer than an Earth day.

So, through the three months,
we managed to cycle through

every possible time zone
about three times over.

But it was really exciting
to have everyone there.

And this is a meeting of the science
operations working group that you see.

In my own role in operations,
when I’m on duty, I chair this meeting.

It’s a lot of balancing the requests
that are coming in from the

geology theme group,
and the environmental theme group,

and trying to fit those in
with the tactical planning day.

So where do things fit
with our overall objectives?

What targets are going to
help you meet those objectives?

What instruments do you need to
collect the necessary observations?

And what is the relative priority
of all of those activities?

So we spend about a full day on
Earth planning what the rover is

going to do that day on Mars,
and then we uplink all of the

commands in a bundle
at the end of the day.

And then come back
in the next morning,

and you have all this
new data to work with.

But these days, everyone has gone back
to their respective institutions, so instead

of looking like this big meeting here,
it’s a lot of telecons, actually.

All right, so let’s
actually go to Mars.

So this is Curiosity’s
landing site in Gale Crater.

And you’re looking at topography.
So this is from the Mars Orbiter Laser

Altimeter, and the colors – the reds and
yellows represent really high areas.

The blues and purples
represent low areas.

And you can see Gale Crater is this
large crater right there in the middle

that lies on this dichotomy boundary
between the relatively high cratered

southern highlands and these
relatively smooth northern lowlands.

And you can see that Gale actually
represents the lowest point in this scene.

That white color
there is the lowest.

And so the argument was made,
if there ever was widespread

atmospherically derived water,
and it flowed downhill,

that Gale would represent
the likely reservoir.

You can also see it lies
within this swath of kind of

northeast-trending channels,
going from lower left to upper right.

And it’s also a very old crater.
So this is dated to about

3.5 to 3.8 billion years old, at a time that
we think Mars might have been wetter.

In terms of the size, you can see it’s
about 155 kilometers in diameter,

which is about 100 miles – maybe the
distance between here to Santa Rosa.

And you can see it also has this large
central mound in the middle of it.

So this was an opportunity
to study a class of craters

on Mars that all have
these central mounds.

We also wanted to go to Gale because,
looking at it from orbit,

we saw some intriguing
geomorphic features.

So here the colors represent lines
of similar elevation contours.

And so, if you had water in there,
this might represent potential

closed basins, or potential areas
where lakes might have persisted.

And these closed contours actually
correspond to interesting channel suites

that come in at different
elevations around the crater.

And then, of course, the central
mound is called Mount Sharp.

And it contains more
than 5 kilometers of strata.

And so we wanted to go there and
kind of read all the stratigraphic levels,

like pages in a book, and figure out
the environmental history.

And if we zoom in to the flank of
Mount Sharp there, also,

prior to landing, we noticed that
there were some intriguing

mineral signatures based on
orbital spectroscopy.

So the colors here – the greens and
oranges represent different clay minerals.

And then the magenta and blue
represent different sulfate minerals.

And the clays are often indicative
of aqueous environments,

and the sulfates are often indicative
of a very acidic environment.

So we’re seeing potentially
some large environmental change

going on here that we want to
go investigate in more detail.

Okay, so actually getting to Mars.
So Curiosity launched on

November 25, 2011 – sorry, 26th.
I can’t read – on board an

Atlas V rocket
from Cape Canaveral.

And we landed on Mars
on August 5th, 2012.

So you’ll notice that’s just about
five years ago, so we just celebrated

our fifth birthday on Mars.
[laughter] Happy birthday, Curiosity.

And, as you might remember from the
news around that time, we had a

very interesting way of approaching
the entry, descent, and landing on Mars.

So because Mars has some atmosphere,
but it only has a thin atmosphere,

we can’t rely on just a
parachute in order to safely

slow down the spacecraft
to get it to the surface.

So we had to do a combination of the
parachute descent and powered descent,

where you’re firing retro rockets,
and then that’s slowing you down.

And then this really
intriguing part of the process

called the sky crane,
which you see here.

So essentially, those rockets are
slowing you down, and then,

when you get very close to the surface,
the rover comes down, wheels fully

deployed, hanging by these
tethers to this landing platform.

And as soon as those wheels
make contact with the surface

and the line goes slack,
that landing platform – the cables

get cut, and that platform goes and
crashes elsewhere, and hopefully not

right on top of your $3 billion rover.
[laughter]

Fortunately, this all worked very well,
and it made a bunch of people

in blue shirts – these are the
EDL engineers – very happy.

And meanwhile, at JPL that day, all the
scientists were gathered in another room,

and the engineers basically said,
here are the keys. She’s yours. [laughter]

So this is one of the first images
that we received from Mars.

This is taken from the hazard
camera on the rover’s chest.

And so you can see the right
and left front wheels there.

The sun is behind us, so you’re seeing
the long shadow of the rover there.

And then, there in the distance,
looming in the distance,

is that mound, Mount Sharp.
And some of the first words that were

uttered were, touchdown confirmed,
let’s see where Curiosity will take us.

So where
did it take us?

This is another perspective
view looking at Gale Crater.

The black circle there
represents our landing ellipse.

And – yep, and prior to landing,
the team embarked on this

large-scale geologic
mapping effort.

And so what you’re seeing here are some
of the results showing the six different

geomorphic units that we identified
in those different colors.

And where we landed is
that white dot that you see,

which is at the distal extent of this
large alluvial fan that extends

from the northern crater rim, shown
in that tan and brown colors here.

So this is the rover’s traverse from
where we landed back in

August of 2012 to our present
location in August of 2017.

So you can see that we’ve covered more
than 16 kilometers in total odometry.

And the yellow line is showing the
traverse, and those teal triangles

are showing areas that we
investigated in much more detail.

I should also point out
that some of the names here

might be familiar
from Earth names.

So prior to landing, we actually
divided up that landing ellipse

into 1-kilometer-square quads.
And then each quad was assigned

the name of a town on Earth
of less than 100,000 people.

And then, as we drove through that area,
any rock target that we investigated

in more detail was given a name
from a geologic unit or formation

or feature from that town on Earth.
So you’ll probably see a few

familiar names, but I promise you,
these are on Mars.

So what I’d like to do in this talk,
I’m just going to give a brief overview

of some of the geology that
we saw along this traverse,

starting with when we first
landed back at Yellowknife Bay.

And this is one of my
favorite images from Mars.

So this is actually a
view from orbit from the

high-rise camera on board the
Mars Reconnaissance Orbiter.

And it’s looking down on our
landing site at Bradbury Landing.

And you can kind of see this
blue and kind of darker toned area

where those retro rockets that we
were firing during landing actually

blew away all of the dust,
exposing some of the bedrock there.

And then, you might faintly
be able to see some rover tracks

that are leading down
into Yellowknife Bay.

And there, where that arrow is pointing,
is actually Curiosity glinting in the sun

smiling back up at us.
[laughter]

So I love this image, and it also
points out why we wanted to

drive down into Yellowknife Bay
because it lies at the intersection

of these three
distinct geologic units.

So we had the hummocky plains
unit that you see here on the left,

this bright bedded fractured unit
on the upper right, and then down here

on the lower right is this cratered
surface. So we wanted to go down

and have the opportunity to sample
each of those different units.

So one of the first things that we saw on
Mars were evidence for conglomerates.

So here you’re looking at nice
rounded pebbles, some hints

of stratification in there.
Some of these showed hints of

imbrication where the clasts
are lined up like dominoes.

These are nice clast-supported
rounded pebble conglomerates,

and this is really the first opportunity to
investigate these and realize that we

had evidence of shallow streams
flowing across the surface of Mars.

So this is a great
welcome to Gale Crater.

But of course, these were just
isolated outcrops – only about

5 or 10 centimeters thick –
so we had a lot of exploring left to do.

So as we continue driving
down into Yellowknife Bay,

we approach an outcrop known as
Shaler, which you see here.

And we were immediately
struck by these beautiful

cross-stratified sandstones.
So your eye can probably pick up

on some of these beds that are
dipping down to the left

with some other cross-bedding
that’s superimposed on them.

Then, at the grain scale,
we were noticing nice rounded pebbles,

some of which showed
these little indentations,

or collision marks, that tell us
about the bed load transport.

And then, at the outcrop scale,
down here at the lower left,

we were able to identify some
outcrop-length surfaces

that are represented by those
different colored lines that you see.

And each of these beds
was defined by a gravel-rich bed

that fined upwards into
some sandy bedforms.

We were able to use that Mastcam
stereo imaging technique to take

some strikes and dips on these features.
And we realized that these beds

are actually dipping about
10 or 15 degrees to the southeast.

And superimposed on that, you have
some nice smaller-scale bedforms.

So essentially, we could reconstruct,
in a lot of detail, that this was a bar

in an ancient stream with dunes that
were migrating along the slope of it.

And all that transport was coming
from the northern crater rim.

And we were also able to say that the
flow of that stream was intermittent.

So we had kind of pulses of deposition.
But at times the flow was sustained

in order to acquire multiple sets
of these dune-scale bedforms.

So this is the
first opportunity to

really do a detailed analysis
of a fluvial deposit on Mars.

And then we finally found our
way down into Yellowknife Bay.

Here you have a nice
image of the arm extended,

and Mount Sharp is
there in the background.

And just as a reminder, this is that nice
bedded fractured unit that we’d seen.

And this was our first opportunity
to really apply the full scientific payload

to understanding an outcrop on Mars.
So the first thing that we did is we

brushed the surface to clear off the dust
and see the actual bedrock underneath.

And you can see – here’s kind of the
wire brush down here in the corner.

And we brushed that surface.

We revealed a nice gray
fine-grained mudstone underneath.

And this was a very soft rock.
You can actually see places where

we scratched the surface of the rock
because it was so – it was so soft.

And then we used the alpha particle
x-ray spectrometer to tell us about

the bulk chemical composition of
both this rock and then an adjacent rock

that showed some white
little veins running through it,

to be able to say that those other
white veins that we’d seen were

calcium sulfate, which are
shown in the big blue peaks there.

The next thing we did was actually
drilled for the first time on Mars.

So this was a great day on Mars.
You can see our test drill hole

and then the first drill hole on another
planet that was achieved robotically.

And here is an example
of the drill bit and then the

scoop full of some of
the acquired sample here.

Then we used the ChemCam instrument
to assess the elemental composition here

of both the brushed rock,
the drill hole, and the tailings.

And so in that upper image,
you’re looking at the drill hole,

and you can see some remarkable
pointing in order to get those little

laser shot points down into a drill hole
that’s about the size of a dime.

Pretty impressive.
You can also see one of those

white calcium sulfate
veins cutting through here.

And then we also used the
ChemCam instrument to assess

kind of the drill tailings compared to
some of the surrounding bedrock.

Next we ingested some of that
sample into the rover to be able to

do x-ray diffraction and
figure out the minerology.

So here’s an example of typical sand
on the left compared to this

mudstone that we were
investigating here on the right.

And the main difference
is that the drill powder

contained abundant
phyllosilicates.

These are clay minerals that indicate
sustained interaction with water.

- [inaudible]
- I’m hearing some “wows.”

That’s a good sign.
[laughter]

So then we finally passed the
sample into the SAM instrument.

And this is just one of the experiments
that we run where you basically

heat up the sample and measure
the volatiles that come off of it.

One of the cool things here, if you look
at that red curve, you’re seeing water

that’s released early, but then also water
that’s released at high temperature.

And that high temperature
release of water indicates

water that was bound up
in clay minerals.

So collectively, this all provides
a lot of evidence for the

first habitable environment that we
were able to investigate on Mars.

So the regional geology and fine-grained
rock suggest that this site was at the

end of an ancient river system or
within an intermittently wet lake bed.

The minerology told us that we had
sustained interaction with liquid water

that was not too acidic or too alkaline,
and it was low salinity.

So basically, if you were
there on the surface

when this water was present,
you would be able to drink this water.

We also found evidence for the
key chemical ingredients for life,

such as carbon, hydrogen, nitrogen,
oxygen, phosphorous, and sulfur.

And the presence of minerals
in various oxidation states

that would provide a source of
energy for primitive organisms.

So within the first couple months
of the mission, we had already

achieved our goal of characterizing
habitable environments.

So this was a huge success.
And I wanted to show kind of

how we can apply that full science
payload to investigate different sites.

Because we’ve now done this about
15 times, and I won’t go into the

detail on all of those,
but this was an exciting place to start,

but we still had
a lot left to explore.

All right, so looking back at
our traverse path, pretty much everything

between Yellowknife Bay and this area
that I’ve circled, along the plains here,

we noticed a lot of cross-stratified
sandstones and conglomerates –

basically evidence for a lot of shallow
stream flows, as we’d seen early on.

But in the vicinity of
this area called the Kimberley,

things started to
look a little bit different.

So from orbit, this was an area that
we had identified a new geologic unit

that’s shown here in the blue that
we called the Orbital Striated Unit.

And that’s because,
from high-rise images,

you can see the arrows point to a
couple of these different outcrops.

You might be able to faintly
see some lineations that trend from,

you know, kind of lower-left
to upper-right, which is,

you know, southwest to
northeast in this image.

And these are remarkably consistent over
many kilometers where this is exposed.

And at any given place,
it’s exposed for about,

you know, 50 or 100 meters
that you see these lineations.

Here’s just a rose plot
showing that consistent trend.

And so this was going to be
our first opportunity to

go and characterize
this on the surface.

However, around this time
in the mission, we started to

notice a lot more wheel wear that
we had expected to find on Mars.

So these are some holes that
are not supposed to be there.

Which is basically telling us that
a lot of the rocks that we were

driving over were much harder
than we anticipated.

They were much
better cemented.

They were eroded by the wind into
the some really sharp, pointy rocks.

So we needed to
change our drive strategy.

We had been driving on the
topographic high areas because it

gives you a good vantage point.
But suddenly, we needed to

start driving in these topographic
low areas – these valleys –

because the sandy cover provides
more protection for the wheels.

So one of the places where
we first made that turn to

go down into a valley was
at this place called Dingo Gap.

And we basically had to drive up
and over this little transverse

windblown bedform here to get down
into what we call Moonlight Valley.

But the advantage to the geologists
from having changed our drive strategy

is that suddenly you’re driving
through valleys with beautiful

exposures of several meters
of stratigraphy on either side of you.

So this actually worked
out quite well for us.

And, as we drove into Moonlight Valley,
one of the first things we noticed

lower in the section, again, were our
familiar cross-stratified sandstones,

some evidence of small-scale ripples
and dunes, some nice pebbly

sandstones there, all indicative
of transport by shallow streams.

But then, higher in the section,
we noticed these conglomerates.

And these are poorly sorted,
weakly stratified. And we’re starting to

compare these to what we had seen
with the previous conglomerates.

And these looked a little bit different.
For one, they contained clasts

of other sedimentary rocks.
So here are a couple of examples of

other sandstone clasts that got ripped up
and incorporated into this conglomerate.

So this is telling us we
had a high-energy event.

We also noticed some subangular clasts
up about 6 centimeters or so in diameter.

So this was a really, you know,
like I said, high-energy fluvial event

and different conglomerates than
what we had seen early in the mission.

So when we look at the distribution of
these conglomerates, here I’ve outlined

in white where they occur in these, you
know, different lenses that we see here.

And we actually recognize that
these are discrete channel bodies.

So previously, we had mostly seen
evidence for unconfined flow,

probably sheet floods. Suddenly we’re
starting to notice discrete channels.

And taking a closer look at those,
we realize that the conglomerates are

incised into some underlying sandstone
beds – a couple examples there.

And so this is telling us about some
event that is really drawing that

gravel-front basin where it’s –
so it suggests some sort of

high-energy event –
a drop in base level or perhaps

lake level that we would
expect to find downstream.

So as we continued driving,
we wanted to keep an eye out

for potential evidence of
that lake-level drop downstream.

So there are three main
outcrops that we looked at.

So I just showed you Dingo Gap
and Moonlight Valley.

And then, as we drive towards the
Kylie and Kimberley areas, this would

be our first opportunity to characterize
that striated unit on the ground.

So we got to Kylie.
This was the view.

So you’re looking towards the east.
And keep an eye out for things

that might look like those striations
from orbit – that we suddenly

started realizing corresponded
to these south-dipping beds –

beds that are dipping
to the right in this image.

So this is your ooh and aah moment.
So I will run through that

one more time as we pan across Mars,
and you can imagine that you’re

standing there on the surface. [audience
reactions] There we go. [laughter]

All right.
So this was a beautiful scene, and,

you know, we realized these
correspond to south-dipping beds.

And there are even a few places
where we noticed small deltas

that were migrating southward.
So this is a cute little delta where

you can see some of these topsets that
are rolling right over into foresets.

And then, as we continue
driving into the Kimberley area,

we recognize
the same thing.

So here you’re looking towards the
west-southwest, so all of those striations

from orbit actually correspond to
beds that are dipping to the left here.

And again, seeing evidence
for those small-scale deltas,

where topsets, again,
rolling right into foresets.

So this is the first place that we really
recognize this delta clinoform geometry.

So previously in the mission,
most of the stuff that we saw

corresponded to kind of river processes.
And now suddenly we’re in this

more transitional area recognizing slope
processes and small-scale deltas.

And all this is predicting that, as we
keep driving deeper into this basin,

further into the basin, that we would
expect to find some lake deposits.

All right, so to summarize on our
traverse path, everything we saw

early on I’ve labeled as fluvial,
meaning shallow streams and rivers.

Then we’re in this kind of transitional
period around the Kimberley,

where we saw evidence for deltas.
And now we’re going to take a look at

an area called the Pahrump Hills and
then an area called Hidden Valley.

Here is just another orbital
image looking down on those.

This is some nice color data
from the high-rise camera.

And you can start to see a different
geologic unit that’s cropping out here –

kind of that lighter-tone tan unit
that you see in a few places.

So we drove down into
Hidden Valley, and sure enough,

we finally found our beautiful
fine-grained, evenly laminated –

almost rhythmically laminated deposits
that are reminiscent of lake varves.

So we finally found our lake deposits,
and this was very exciting.

And there were even places
where you can see these lake deposits

that are overlain by fluvial
and deltaic deposits.

So looking at this section as a whole,
you see some nice thin laminated

mudstones overlain by more
thickly laminated or thinly bedded

sandstones and up into
cross-bedded sandstones.

And as we continue driving,
this is an area called Pahrump Hills.

Again, we saw those beautiful fine-
grained, evenly laminated lake deposits.

So we finally have evidence for a
longstanding body of water on Mars.

And so putting that all together,
this is kind of the environments

that you – that we found,
from fluvial to transitional,

into this lacustrine,
meaning lake deposits.

And pretty much everything
that we’ve seen for the last three years

of the mission has been more
evidence of those lake deposits.

But it would be a pretty boring talk
if I just showed you evidence

of fine-grained evenly laminated rocks.
So, instead, I’m going to focus on

some of the more unique things
that we have seen through this section.

All right, so I should have pointed out
too that there is this – all of these

dark features that you see here
correspond to dark basaltic sand dunes.

And these are active
windblown sand dunes.

So we had the opportunity to go
and look at these and study

active windblown sand dunes
and current processes on Mars.

So again, this is a
high-rise orbital image.

All of those lake deposits that I showed
you are part of the Murray Formation.

We’ll talk about the
Stimson Sandstone in a bit.

But before we got there,
we kind of found this gap in the dunes

where we could safely
bring the rover in, not get trapped

in the sand, and investigate
some of these dunes.

So one of the first images that
we acquired was this gorgeous shot

of the Bagnold Dunes.
So here your eye is probably just

picking up on some of those multiple
scales of bedforms that we see here.

And we were able to back the rover
right up to the lee slope of one of these

to be able to assess some of the
morphology of this dune in more detail.

So here we’re just comparing
the morphology of the dune to

things that we see on Earth –
some of the similar processes –

we’re seeing evidence for
grain flow, areas of grain fall.

You know, I’ve just labeled the
brink, horn, and toe of this dune.

All very similar to windblown
dunes that you see on Earth.

And there were other areas we
were actually able to use the wheel

and kind of scuff into the dune.
This is our way of trenching into it

to compare what we see on the surface
to some of the stuff that’s underneath –

look at details of the
grain size and composition.

But the other thing that
I wanted to point out here

is the multiple
scales of bedforms.

So on Earth, we’re probably
used to seeing these nice little

wind ripples that are superimposed
on a larger-scale dune.

But what’s different here on Mars
in this intermediate scale of bedform.

Here’s a couple of
these that are labeled

that have kind of
meter-scale wavelengths.

These are still small ripples
only a couple centimeters tall.

But they have sinuous crest line –
very asymmetric profiles.

And this is actually the result of
a different process on Mars.

So we call these fluid drag ripples.
And they’re the result of Mars

having a much thinner atmosphere.
So it’s pretty cool to go to Mars and

see something that’s completely
different from what we see on Earth.

We’re also able to do
change detection experiments.

So this is using the hand lens
imager at the end of the rover’s arm,

looking down on
one of these ripple crests.

And here – a couple of the areas that
are circled are areas that you might

see some change as I flip back and
forth between these two images.

So these were taken
about three minutes apart.

And you can actually see some little
sand grains that are saltating by.

So pretty cool to see these
active processes on Mars.

But we’re not just looking
down at the rock and soil.

We’re also remembering
to look up sometimes.

So in light of last week’s great
American eclipse, I wanted to

show you a solar eclipse on Mars.
So Mars has two moons,

Phobos and Deimos, which are both
thought to be captured asteroids.

And we sometimes
look up and see the transit.

Here’s a transit of
Phobos crossing the sun.

And by observing these events,
we’re actually better able to

characterize some of the orbital
parameters of these moons.

Pretty cool, but we’re not
going to capture totality here.

These are tiny moons. I think Phobos
is about 14 miles across or so.

Okay, and with the remainder of
the talk, I’ll just go into some of

the other additional weird geology
features that we’ve seen in this part.

So starting around this
area called Marias Pass.

So I showed you before
all of those lacustrine

mudstones were part of
the Murray Formation.

But here at Marias Pass,
we recognize for the first time

this very sharp unconformity
with the sandstone that overlies it.

When we take a closer look at
what we’ve called the Stimson

Formation sandstone, we see
beautiful sets of climbing dunes here.

And taking a look in even more
detail here, this is just annotated

showing some of those nice sharp
truncations of set boundaries

between different sets of dunes here.
The white is highlighting the foreset,

so this is able to tell us which
way the dunes were migrating.

We can look at the geometry
of the cross-bedding to reconstruct

the shape that these
dunes might have had.

And interestingly enough, some of the
details even reveal these small-scale

ripples that correspond to that new
unique bedform that we saw on Mars.

So this is telling us that, at the time
that this sandstone was deposited,

the atmosphere on Mars
was already much thinner.

So again, here’s just a schematic diagram
reconstructing what we call the Stimson

Formation, which is a dry eolian dune
field, meaning windblown dune field.

And so based on the geometry
of the cross-bedding, we can say

that these dunes had
sinuous crest lines.

We don’t actually see any evidence
for interdune deposits, so we know

this was a pretty dry environment
when this was laid down.

And this is also just
depicting that unconformity

with the underlying Murray
Formation shown in purple there.

And using kind of the dip direction
of all these foresets, we can reconstruct

that the paleotransport direction was
towards the northeast, which is actually

the opposite direction from the modern
windblown Bagnold sand dunes.

So pretty cool to be able to
compare both modern

and ancient environments
at the same time.

And then, as we kept driving –
this is through an area called the

Murray Buttes – most of the buttes –
all of the kind of steep cliff faces

were made up of that
Stimson Formation sandstone.

And everything that
we were driving on –

this nice tan color here – represents
the Murray Formation mudstone.

But we started to notice some
differences in the Murray Formation.

So rather than that nice evenly laminated
mudstone that I showed you before,

we’ve recently started noticing evidence
for what we call ripple cross-lamination.

So this is telling us that we’re
getting into shallower water –

or shallower lake deposits
or perhaps some, you know,

evidence of streams and
rivers entering this lake.

And this is just compared to
an example from Earth of the

Triassic Moenkopi Formation
on the bottom there.

We also started noticing
some large-scale cross-bedding.

And this is in the Murray Formation.
This was the mudstone before.

We’re now suddenly noticing
what might be evidence for

wind reworking of
some of those sands.

And then we have beautiful
examples of desiccation cracks.

So here you’re looking down on a
bedding plane and noticing all these

little polygonal fractures
at kind of a centimeter scale

that tell us that we had
repeated wetting and drying.

So suddenly we’re either
getting to more marginal parts

of this lake or
into shallower water.

All right, so to summarize all of these
environments that I’ve shown you,

we have this block diagram that’s
just a schematic of the different

sedimentary environments, and then,
in the foreground, kind of this cross-

sectional view, the different groups that
we were driving through with the rover.

So the red line represents
Curiosity’s traverse path.

Essentially on the top surface,
what you’re seeing is that we

had erosion of the northern
crater rim that carried water

and sediment in these shallow
streams kind of into the basin here.

At times, we had
lakes that were present.

These were – you know, noticing
variations in lake level through time.

But we had deltas that kind of
marked the extent of that lake.

Sometimes we had some nice
dune fields around the margins there.

But essentially,
what Curiosity has seen

was all of the evidence for,
you know, shallow stream deposits.

Then we approach those delta deposits,
and we spent much of the last three

years exploring these lake deposits.
And the squiggly lines, zig-zags,

that you see there show that,
at any one time, those environments

were kind of interfingering
as we’re filling in the basin.

So the regional summary here in text
is that we had erosion of the

northern crater rim that
generated gravel and sand

that were transported southward
in shallow streams.

Over time, the stream deposits
advanced towards the crater interior,

which transitioned downstream
into finer-grained,

southward-advancing
delta deposits.

These deltas marked the boundary of an
ancient lake, or lakes, where mud-sized

sediment accumulated and infilled both
the crater and the internal lake basin.

However, we know that
occasionally there were drops in

base level or lake level that are inferred
from those incised channels and also

that we had intermittent dry periods
that were recorded by these eolian,

meaning windblown, sand of the
fluvial and lacustrine lake deposits.

So this artist’s representation here on
the bottom just kind of shows going

from dry to wet to dry conditions,
noticing that we had those fluctuations.

But the really cool take-home story
is that, based on the thickness of

sediment that we’ve seen in these lakes,
we know that we had longstanding

periods of water on Mars for
probably anywhere from hundreds

to tens of thousands of year. So it’s
been a pretty exciting journey so far.

And then,
with the remaining time,

I just want to point out
where we’re heading next.

So this is a Mastcam image looking
up that mound, Mount Sharp.

So in the foreground,
the dark band that you see –

so those windblown sand dunes.
The Murray Formation

where all those mudstones –
and today on Mars,

we were actually investigating
the hematite ridge.

So you can see kind of this pinkish-
reddish color associated with that.

And we have our eyes on the clay unit
and then the layered sulfates beyond.

And looking at how that plays out
with the overall mission so far –

so we spent the Prime Mission –
those first two years – we were

mostly investigating those
shallow stream deposits and

getting into our first real
lake deposits at the Pahrump Hills,

with the exception of
Yellowknife Bay early on.

Then, in the First Extended Mission,
we spent most of that investigating

that Murray Formation –
all those mudstones with

a little bit of that Stimson Formation
separated by the unconformity.

And now, we’re really
starting the climb here.

So I should point out, this is 14 times
vertically exaggerated. [laughter]

So we’re not actually climbing
slopes that are that steep.

But it really does highlight how much
of this mound we’re really climbing.

And so today on Mars, we’re at that red
arrow investigating that hematite unit.

And we’ve been doing
some reconnaissance.

So this is, again, a Mastcam image
in the upper left compared to a

high-rise orbital image of the
area that was targeted.

And you can see that using that
ChemCam Remote Micro-Imager –

and this is a mosaic of about
10 of those frames stitched together.

We can really bring out a
lot more detail in the mound

and look at some of the bedding
geometries that we might see there.

And we’re also using
Mastcam to do that.

So here is a beautiful Mastcam
view looking at some of the

bed thicknesses and bedding
geometries that we might see.

Another ooh and aah moment.
[laughter]

And then I will just leave you with,
this week on Mars –

so this is our traverse path
right up to this hematite ridge.

This is the ridge that you
can see cutting through here.

And basically,
we’re right at that blue star.

And we are planning our
drives kind of up this shallower part

of the slope to be able to
investigate this hematite unit.

And, as we’re driving up,
this is our view.

And we are doing some systematic
sampling along the way, looking at

variations in chemistry and sedimentary
structures that we see in these locations.

So we’ll end on that and just say that it’s
been a lot of fun to be along for the ride,

and I’m looking forward to the
next five years, hopefully,

of exploring Gale Crater.
So thank you very much.

[ Applause ]

- Okay, thank you, Lauren.

And now we’ll open it to any
questions from the audience.

Again, for the benefit of our
streaming audience, if you have

a question, please use
one of the mics up here,

or I can bring you this
handheld mic as well.

- So thank you very much.
There was a beautiful shot of the

rover with its – one of its wheels.
You said it was abrading, digging.

I assume you were not there
holding the camera. [laughter]

- Yes.
- At that time.

And so, did you cheat
on the image?

Or how did you do that?
- Great question.

I keep forgetting
to point this out.

So that is taken with the camera
at the end of the rover’s arm.

And it’s actually not just one image
that allows us to take that selfie.

It’s dozens of images that
are stitched together.

And they’re stitched together
in such a way that you can

stitch out the arm because you
have other coverage of that area.

So, no, we’re unfortunately not standing
there on the surface taking that image.

But it’s a great way,
by taking these selfies,

of kind of documenting,
you know, how the rover is doing

and also these investigations
that we do in more detail.

- Oh, you were …
- Okay.

Thank you. That was amazing.
So two questions.

One is, I could easily see, could you do
the rest of your entire career with this?

I mean, it is so cool.
But you hear of

these things going on and on.
But the real question is, have you seen

anything like folding or any of the other
things that we see in sedimentary

formations and other larger –
signs of motion like that, large-scale?

- Yeah. So we haven’t seen any
large-scale structural deformation.

But at the small scale, we have seen
some soft sediment deformation.

So really water-lain, you know,
sediment. Kind of, fluid is escaping.

So more on the tens of
centimeters’ scale deformation.

Good question.

- With the atmospheric pressure as
it is today, how much of a gap is there

between the freezing point
and the boiling point of water?

Or is there any gap?
- [laughs] That’s a great question.

So actually a lot of surface
conditions on Mars exist at that

triple point of water right now.
So it’s at exactly that point.

- So there’s not much prospect
of keeping liquids around.

- [laughs] Exactly.
Pretty challenging.

- So it was a great talk.
Thank you very much.

What’s the sort of time scales
upon which you plan?

It sounded like the very next day’s
drives are sort of discussed and

programmed in just the previous day.
Is that typical? I mean, that’s …

- Great question.
So we plan on a couple different scales.

So something like this large-scale
campaign where we want to investigate

this ridge that has the hematite signature,
that’s been – we’ve been planning

that for months, actually, of, you know,
what will we do when we get there?

What’s the best traverse to get up there?
Then we also plan at kind of the

week-long scale – the long-term
planning role on the team is looking at

what we call the sol path – like,
you know, Monday, Tuesday,

Wednesday, Thursday, Friday,
what are we doing each of those days?

But we really come in tactically
and can make complete changes

to that plan based on the data
that you receive the day before.

The drives are usually –
we try and have a good head start

on where you’d
want to plan things.

So we do our full planning day, and then
at the end of the day, we call it n-plus-1.

So what’s tomorrow
going to look like?

And we can put some
placeholders for activities in there.

You can start to think of where
exactly you want to be driving.

But it really does require all those
different scales of planning.

- I just had a general question –
a couple of them.

So what is the rover made of?
And also, you know,

if there’s mechanical parts,
how does the maintenance take place

with all the
weathering the elements?

- Great questions.
You know, I don’t know all of

the materials that are present.
We obviously use aluminum – you know,

things that are lightweight but also have,
you know, some structural integrity.

But, you know, all sorts of different
insulating materials as well.

In terms of mechanical maintenance,
unfortunately, we can’t do any.

So when an issue comes up,
it’s going to probably stay that way

for the rest of the mission.
So instead, we start coming up

with creative solutions to work with
something in that new configuration.

And fortunately, if software issues
come up, we can upload new

software and make those changes, but
mechanical issues are hard to come by.

I should also point out we have
the wheel wear under control,

so don’t worry.
Those wheels are expected

to last for many more years
and help us up this climb.

But it was just an
interesting find early on.

- So this is kind of two questions.
One is the housekeeping,

along the lines of, you’re saying if
things break, you don’t get to fix them.

How do you keep the lenses
clean on all these equipment?

And the camera, right?
- Yes. Great question.

And so I showed you that image where
we had the – you know, looking down

at the ripple crest,
seeing little saltating sand grains.

And that made the instrument PI for
that camera very, very nervous that day.

So we have a dust cover that
covers over the MAHLI instrument.

And so sometimes you
can image through that.

But for some of these, we will allow
the dust cover to be off, take the image,

and immediately close it.
- Got it.

And the other question is,
when you’re looking at these

amazing photographs of the
sediments and things like that,

and you’ve got an angle to a lot of
these sediments, how would you tell

if there’s – if it’s – if there’s some
seismic influence there, or there’s

no way it’s seismic, it’s all based on
the mechanics of falling downhill?

How would you know
what you’re looking at?

- Yeah. Fortunately,
Mars has helped us out,

and there are certainly enough very
planar flat surfaces that are in between

some of these inclined, you know,
beds that we see the cross-bedding in.

And so you wouldn’t be able to
just deform one part of that section

without deforming
all of it if it was, you know,

due to earthquakes or
other structural deformation.

And also, the angles that
we’re seeing for some of these

inclined beds are all
things that are consistent

with primary
depositional slopes.

So nothing really out of
the ordinary with that.

- Thank you.
- Thanks.

- You – here.

You’ve done a lot of study of the
chemistry of the soil of Mars.

If and when homo sapiens ever arrive at
Mars, is there a chance that they could

do any chemistry that would withdraw –
extract air or water from the surface?

- Ooh, good questions.
And I don’t know the answer in detail.

I don’t know if someone else
wanted to comment on that,

but in terms of extracting water on Mars,
so water on Mars is hard to come by.

There’s, you know, subsurface ice
that we’ve noticed in more of

the northern regions.
But the water that we’re

finding here is just tiny amounts of
water that are bound up in minerals.

You know, we’ve been looking for
CO2 frost in Gale, but there is not

a whole lot of moisture if you went to a
place like this in the equatorial region.

So you’d probably
have to extend your reach

to more of the higher latitudes
in order to find that.

- Speaking of …
- Okay. Oh, yeah, okay.

So if nothing forces a stop on this,
what’s the potential life expectancy

of the – of the whole system?
How long could it keep going unless

something collapses and blocks it?
- Great question.

We obviously hope forever,
but I mentioned that the

power for this rover
is a plutonium source.

And that source is decaying over time,
meaning that we are getting less and less

power from it than we
did early on in the mission.

So some studies suggest that around
year seven or eight that we might start to

notice a significant drop-off in the power
that we have available to do operations.

So it’s not saying
it’s going to end then.

It’s just that we will notice
the impact on operations.

So, you know, hopefully, 10 years.
Hopefully more.

But keeping in mind that our power
will be the limiting factor, I think.

- Two age-related questions.
How do you tell how old a crater is?

You mentioned the
age of the Gale Crater.

And then, how long ago do you think
there was bulk water on Mars?

- Good questions.
So the age of Gale Crater

was based on crater counting.
So based on the number of craters

that a given surface acquires over time,
and scaling that actually with dates

that we have the moon from the
Apollo samples that were brought back,

that’s the best that we can do right
now on Mars is crater counting.

So Gale is thought to be
about 3.5 to 3.8 billion years old.

And a lot of these environments that
we’re investigating within Gale,

we think probably occurred
shortly after its formation.

So also thinking that that water was,
you know, kind of upper 3.5 and above

in terms of the age.
Good question.

- Since we know there was water
on Mars, are we able to say that

the water left or evaporated faster in
this location versus that location?

Like, the equator versus poles
versus hills versus valleys?

Is there anything that tells us the water
stayed around longer in this area and

went away really quick in that area?
- That is a good question.

- Please repeat the question.
- Oh, yeah. So the question was,

is it possible to say that, you know,
water went away in different

parts of Mars of different times?
We know that it was once wetter.

Did it all disappear at the same time,
or were there regional variations?

You know, I’d have to defer back to
the geology that we’re seeing here

that tells us for sure that we had
water flowing across the surface.

You’d really want to
compare that to a bunch of

other places on Mars
and know those relative ages.

I’m not really sure, other than that,
if there would be a way to tell.

Probably require a lot
of modeling as well.

So we know that Mars used to have a
thicker atmosphere and, you know,

that a lot of that
atmosphere has escaped.

That’s actually something we’ve
been able to measure using the

SAM instrument on MSL,
looking at deuterium-to-hydrogen ratios

and essentially proving that we had
a thicker atmosphere early on.

So in terms of figuring out
regional differences, though,

I think the geology would
just be the way to go.

- [inaudible] another operations question.
I imagine something like [inaudible] is

very over-subscribed in terms of people
wanting to do experiments on it.

And is something similar happening
to the rover in terms of just way more

people have – I want to do this,
I want to do that, I want to do that,

and just not time, or we’ve got
to get moving or whatever?

How does that sort of boil out?
- Yeah. So I would say we have a

ton of data that’s been brought back
from Mars that anyone is – you know,

that wants to can go and look this up.
If you actually go to this JPL site,

you can look at all of the new
raw images that come down.

They’re posted within a day or so.
And also the Planetary Data System –

the PDS – we systematically,
every six months or so,

will put all of the chemistry data
and from all the other instruments –

that is all made
publicly available.

So there’s a ton of data to work through
that a lot of people could be working on.

But in terms of the actual time that the
rover has each day to do operations,

you are fighting for that time.
Like, each day, even the geology theme

group compared to the environmental
monitoring theme group is fighting

over the same limited resources
that we have that day on Mars, so ...

- And you’re running that meeting?
- Yep.

- Oh, boy. [laughter]
- Believe me, it’s not just trying

to balance scientists’ requests.
Then you have to balance the

science requests against what
the engineers are telling you

you can or cannot do.
So it’s always fun.

- Wow.

- Question. You have a
really nice schematic.

It’s sort of a 3D wedge –
yeah, right there.

Could you tell me – two questions.
How far deep have you gone,

or do you plan to go, down into
the bottom of that lake bed?

And how far up on those craters
can you go – can the vehicle go?

- Good question. And something that I
didn’t have the chance to point out here –

I’m just going to change slides really
quick – is that we’ve actually been

systematically driving uphill.
So I was talking about getting deeper

and deeper into this basin, but that’s
really deeper into the different

environments that we’re seeing, even
though we’ve been climbing uphill.

So at any one time,
you probably had rivers

moving into deltas
moving into a lake.

But then you kind of filled in the crater
a bit, and then the next successive,

you know, group of rivers moving
into lakes moving into deltas.

And so it’s showing the
progressive infilling of Gale Crater.

But we’ve mostly been
driving uphill that whole time.

And so we can’t really, unfortunately,
answer the question of how deep into

the basin could you get.
But in order to address kind of how

high we’re planning to climb,
let me see if I have a good –

maybe I don’t have a
good image here at the end.

We certainly hope to get through
these different clay and sulfate units.

And I guess that would
kind of be up through

some of these layered deposits
that you see through here.

So we’ve currently climbed maybe
about 250 meters of total elevation gain.

And I think we want to
get to 400, 500 or so.

- My question’s a little bit along the lines
of what the gentleman over there asked.

I was just wondering, so you found
evidence that there was some kind of

water on the surface of Mars,
but have you found

geological evidence that shows,
like, how it might have left?

And will you be able to
find something like that?

- Evidence of water leaving.
So I guess, in the case of the

lake deposits, you know,
obviously evidence for

evaporation leaves, you know,
behind these desiccation cracks

or evaporite minerals, so salt crystals
you might see on the surface.

But that just, you know,
could vary locally.

So I think the question was really,
large-scale, Mars losing its atmosphere,

losing its water – you know, the water
is currently tied up in the polar caps.

But I don’t know what
evidence you would be able to

look for exactly to say,
this is when this happened.

So it’s a good question we’ll
have to think about more. Thank you.

- I have a question – first of all,
thanks for a wonderful talk –

about the
longer-term strategy.

As I recall, when Gale Crater
was selected, a great deal was made

of Mount Sharp and the
ability to climb up Mount Sharp.

And the first four or five years,
you spent chasing sedimentary activity.

Wonderfully productive.

Was this adapting to
what you were finding?

Or was – or how did that change in
strategy? Or was it a change in strategy?

- Absolutely. So on our traverse path,
you might have noticed that

we took a little jog into
Yellowknife Bay early on.

And so this little
change was not planned.

So essentially, we landed here.
We knew we wanted to get to all of

these units where we saw those
intriguing mineral signatures.

But we – no matter what,
we’re going to have to drive

around the Bagnold sand dunes.
So we don’t want to get the rover stuck

in the sand, so we were always kind of
shooting for this same gap through here.

But in terms of the timeline and how
long it might have taken to get there,

that was because we were getting
distracted with some awesome

geology along the way. [laughter]
So, you know, you’re not going to

pass up the opportunity to characterize
the first habitable environment on Mars

just to say, get on the road,
get to the mountain.

So it was kind of
a mix of both.

- My question has to
do with spacecraft design.

Your rover was designed years
before you actually got to Mars,

and it has all kinds of
great instruments on it.

What have you learned that
would help future missions?

Have you had somebody say, gee,
I just wish we had thought to put that

instrument on that we didn’t have?
Or is there any instrument that you have

that you say, gee, that isn’t turning out
to be as useful as I thought it would be?

- Good question. I mean, I think,
for this mission, the instruments

that we have are very well-suited
to the science objectives.

But if, for example, you’re really after,
you know, looking at organic minerals,

for example, you might change –
and for the March 2020 rover,

we have instruments that are capable
of doing Raman spectroscopy.

So I think it really goes back to,
what is the objective of the mission?

These are well-suited.
I’m excited to see, you know,

new results from different
instruments on 2020.

Other than saying, put some heftier
wheels on that [laughter], I don’t know

if there’s too many lessons learned of
how we would change that. Thank you.

- Thank you for a great talk.
It seems like Gale Crater was

chosen because there was all
these unique features in there.

Would you be able to extrapolate
this to the rest of Mars?

Or is this specific to a
particular area that you’ve found?

- Good question. So I think,
through some geologic mapping,

you might be able to identify
nearby some other similar features.

But this is a lot of the
detailed geology that

we’ve been doing,
just tells us about this local area.

It’s certainly encouraging to find
such diverse sedimentary environments

here and longstanding evidence
for aqueous alteration.

And so that would – you know,
you would presume that you would

find that other places on Mars as well.
But it’s hard to say that exactly

these same environments might
be present in the next crater over.

- Thank you. One more question.
So on the operational side, is it –

you said something about batching
instructions and sending it over so

that it can execute the commands …
- Yep.

- … the next day. What about, like,
day-to-day operation –

minute-by-minute operations?
If it were, like – as you’re driving

through, are you getting feedback
at different points to decide that

this is not a path I want to go forward
on, and I want to change things around?

Or is it always something
of a plan to – that it follows?

- Yeah. So unfortunately, based on the
signal delay between Earth and Mars,

which varies based on where Mars
is in its orbit from a couple minutes

up to about half an hour,
we can’t do real-time observations.

So it’s not – you know,
you’re not just sitting there

waiting for the image to come down.
We really do plan a full day on Earth

and then see what – you know,
upload those commands

at the end of the day, kind of
carries it out over our nighttime.

You come in the
next morning to new data.

And so I mentioned
that the Martian day

is a half an hour longer
than the Earth day.

And so we’re no longer living on Mars
time, but we do need to kind of adjust

our schedule to when we can get those
orbiter passes to give us new data.

And so sometimes we have to start really
early in the morning or start kind of later.

And when our schedule gets
completely out of whack with Mars,

we have a skip day in
trying to catch back up to it.

So that’s how we deal with
Mars time these days, which is

much nicer than round-the-clock.
But unfortunately, it’s not real-time.

- Thanks.
- Thank you.

- A couple more questions,
if you’ll indulge me.

- Sure.
- You mentioned that the retro

rocket actually excavated pits of
some kind and exposed some bedrock.

Did you want to actually take that
opportunity to look at the bedrock?

Or was it contaminated by the exhaust?
Or was it just too difficult to

climb down, or up?
- So it didn’t really excavate pits

as much as it blew
away all of the dust,

revealing some of that
nice bedrock underneath.

And the first things that we
saw certainly looked like those

conglomerates, you know, that I
showed as we drove away a little bit.

But I think we were initially a
little hesitant – you know,

what kind of alteration
might that have – you know,

might that cause, you know,
to some of these rocks.

So we looked at them, thought, hey,
that looks a lot like a conglomerate

that was deposited
by a shallow stream,

but we really wanted to confirm that
with some unaltered rocks nearby.

- And those are beautiful
pictures you have.

I assume that they’re true color.
So how did you do the color balance?

- Good question. You’ll probably
notice in a few of these, the sky on

Mars looks a little blue, which is not true.
[laughter]

The sky on Mars is
actually reddish, kind of dusty.

And so this is just the particular white
balance that’s been applied to some of

these, which is a helpful color
stretch for looking at the geology,

but just keep an eye on – the sky
is not necessarily true to form.

There's a question.
- Pretty informative. I really liked it.

I have a couple of questions.
One is, like, how do you determine

that there is no water underground?
What will be the probe that you need

to use to see that – not just the
surface water but also underground

there is no water?
- Yeah. So we’re actually

using the DAN instrument –
the Dynamic Albedo of Neutrons.

So it’s a neutron spectrometer that can
tell us about subsurface hydrogen.

But again, that’s modeling a lot.
So you kind of have to say, okay,

if we model this depth,
then this amount – you know,

can we match some of
those results that we’re seeing?

And for the most part, the results
that we’ve seen in Gale Crater

are mostly dry. And so that’s
how we can answer that here.

But, yeah, that’s a good
question for elsewhere on Mars.

- Another question is that – is it possible
that our devices also carry some

microbes there, so it can part of the
environment – Mars environment?

How do you make sure that it’s
completely sterilized and didn’t

carry any microbes there?
- Great question.

So this falls under planetary protection.
And we know that we have

a somewhat dirty spacecraft.
So there’s different levels of how

clean your spacecraft has to be
based on whether it’s, you know,

going into Earth orbit or
Mars orbit or the Mars surface

or the Mars surface
where water might be present.

And one of the things that I actually
have to do in my role as the, you know,

science operations working group
chair is, each day I’m asked, is the

plan clear for planetary protection?
Meaning, if we take our somewhat

dirty – it’s a pretty clean spacecraft,
but it still probably has some

Earth microbes on it –
if we take that anywhere near

what looks like, you know,
current ice or water or something,

that would be a violation
of planetary protection.

So fortunately, or unfortunately,
we have not seen any evidence

of current water, ice, on the surface here.
So that’s something to

keep in mind, though.
- So there is no contamination.

- Right. We don’t want to bring
our dirty Earth microbes to Mars.

- So has there been any effort made –
like, you mentioned that –

to also look into the
microbes that might be there.

Because we are finding out in – on Earth,
on the – there are species which can

exist in a very, very harsh environment,
especially under – in the ocean.

- Mm-hmm.
- In very harsh temperatures and

pressures. So is there a possibility
that Mars can have that as well?

- I mean, I guess it’s
always a possibility, right?

And you would hope that maybe
some extremophiles might

be able to take hold here.
But unfortunately, a lot of the surface

environment that we’ve seen on Mars is,
you know, dry, super arid, you know,

oxidizing, acidic, unfriendly conditions
for life at the surface as we know it.

So, you know, maybe if there were
modern microbes on Mars, they might be

deeper underground. But certainly
something to keep an eye out for.

Yep.
- [inaudible] your planning meetings,

are they webcast for public viewing?
- So the question is if the

planning meetings were
webcast for public viewing.

And unfortunately, they are not.
You can’t listen to us

all sit around and argue.
[laughter]

But the documentarian reports that
kind of record how some of those

planning decisions were made,
that’s all made public on this, you know,

Planetary Data System – PDS – website.
So you can’t listen to the meeting,

but you can kind of look through
and see, what are we doing today

on Mars, what are the
observations that made it in,

and any major changes to the plan.
- Okay. Thank you.

- Back to this gentleman’s question
about, you know, we were going to

climb up Sharp, but we spent all this time
wandering around in the flatlands,

and it was great. But did you
actually land where you wanted to?

In other words, had you wanted to land
closer to that bridge across the dunes?

- So we knew – all we knew was
that we were going to land

somewhere within that landing ellipse.
So we – you know, everyone on

the team had kind of X-ed out a
spot where they’re, like,

I predict that we will land here.
[laughter]

I got pretty close, actually.
But, you know, you would hope that

anywhere in there – you know, it’s safe.
We didn’t know the exact traverse

that we would need to take.
You know, we knew that crossing

the dunes would be a challenge,
but if we had landed further downwind

in our landing ellipse, we would have
been around the side of it anyway.

So that wasn’t really something that we
could control, but, I mean, we were –

I think we got pretty lucky because
we were right next to Yellowknife Bay,

and we were able to characterize
a habitable environment.

If we hadn’t really seen that,
we might have been driving

across the plains
for a lot longer.

- I think we’re getting pretty close
to closing here, so rather than

make a question, I’d like to
make a couple of statements.

We here in Silicon Valley
tend to be science-oriented.

So – but I think that I do speak
for the group here in saying that

we feel that NASA is really
spending our tax dollars well.

And so thank you for faithfully
following that initiative.

- Well, thank you for the support
and for all of you for following along

on this exciting mission.
I really appreciate it.

- And secondly, you’re probably
the closest thing to a true space explorer

[laughter] than we’ll ever meet –
making decisions about exploration

in the Lewis and
Clark tradition. [laughter]

- Well, thank you. It’s been a lot of fun.
- So thank you.

[ Applause ]

- Again, thank you all for coming.
Thank you, Lauren.

- See you all next month.

[ Applause ]

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