Well, thank you very much, Don. And once again, I thank everybody for inviting me.
It's great to see some old friends and and make some new friends.
And I'm going to share with you what is about ten years worth of effort in the mission.
I won't be offended if people get a bit bored and leave.
I was told it might be okay to go over my time a little bit and I had a lot of fun with Robotics Group.
We actually met twice, so I stuck in some stuff I normally don't show to show you.
Tell you about our flat tire on on Mars.
And I think that the the place I really have to begin here is well with Mount Sharp, which is what we're exploring with the rover.
The rover right about now is up on this ridge that you see right there.
It's about five kilometres high. This mountain and the crater that we landed in is about 150 kilometres across.
And so part of the problem that has nothing to do with habitability is what is this mountain doing in the middle?
And I don't have a great answer for that, but we'll touch on it a little bit.
Let's see here. Now that'll work.
Okay. So this is the part of the team that that we were formed of when we first landed back in 2012.
This is about 200 people that are responsible for the operation of the rover on a day to day basis.
But the broader team is 500 scientists representing 13 countries, nine principal investigators,
ten instruments that make various measurements in addition to 17 cameras.
So the goal, my responsibility was principally to make sure that the rover was optimised,
to collect data and and sort of keep moving in the same direction to create the path of discovery here.
So really what I'm showing is a lot of data from instruments that I didn't build
in science team members who who contributed a lot to the data interpretation.
I think what I want to do is start by talking about some of the things that puts Mars into a more earth-like
context so that some of you that are not geologists and geochemists can better appreciate what we're doing.
And in my experience with with Mars, it takes a long time to get used to it.
When you're used to working on the Earth and there's a lot of history to learn about to go through.
And so for me, this this history really begins with the Mariner mission at back in the sixties,
which was the first time that geologists ever got to see pictures of the surface
of Mars that shows evidence for some kind of flowing fluid in back in those days.
They weren't sure it couldn't be liquid CO2 or even liquid nitrogen.
But you see these channels back in the Mariner nine data.
Viking comes in about five years later with bigger and better cameras, and the channels didn't go away.
They just got more refined. And so and as the decades went by, that the debate slowed down and most people accepted that these were cut by water.
And then the question became, what happened to that water? So it really becomes a story of environmental evolution.
But the geologists really missed an important part of this problem, which is what happens to the mass that is represented by these channels.
These are bedrock channels. Where does that stuff go?
And so when I first got involved, I always wondered, why aren't people asking this question about where these materials are that were eroded away?
And so there was what I regard as a very big breakthrough by the Mars Global Surveyor mission,
which took these pictures that showed unequivocal evidence for deltas in the rock record of Mars.
And, of course, if you conserve that mass, that's where it winds up.
It goes downstream. But the most important thing is, is that the structure of this feature indicates that there's probably a body of standing water.
And now the discussion of paleoclimate gets really intensive because the implication
of a body of standing water is that it's an equilibrium with the atmosphere.
So that Mars may have had an atmosphere that was more like Earth's the channels that you saw in the picture before, you could be a flash in the pan.
There's an eruption of water. It flows across the surface of Mars, the channel, the water goes away.
And the climate of Mars is not much different from Earth.
But what this picture really required for many of us was that there there should someday be evidence for a wake.
Okay. But before these rovers landed, all we could do is map.
And so this was some mapping that was done by the the team that worked back in the 1990 and early two,
thousands plotting the distribution of these channels, which basically straddle the equator.
They're not observed at higher northern latitudes. And then when I got involved,
what I did was work with my students was to plot the location of just layered rocks
that could be sedimentary deposits that would balance that mass on a global basis.
And not surprisingly, where you see the evidence for erosion, you also see the evidence for deposition.
But you don't know that these layered rocks aren't volcanic. You don't know that they're windblown materials.
They don't have to relate to water. So it still requires vehicles in situ to make measurements and show what these were.
If you go back to the Viking era again,
the history of of wearing was shown in this first image that came back where what you can see is that this valley,
this, this Vallis Marineris, this this canyon is about five miles deep.
And in the upper reaches of the canyon, you see a light toned rock giving way to a dark toned rock,
which is eroding and shedding material down across it.
So that suggested that there was some wearing present in in the upper crust of Mars, but we still didn't know what those things were in this one.
This discussion went on for decades until the Opportunity Rover landed in 2004.
And those of us that woke up in the morning and saw this this picture realised
that this this really did have to be some kind of a sudden entry material,
not a volcanic deposit.
And so the cool thing about it is, is that you can see that everything below this white line is sort of tilted with respect to this line,
and everything above it is flat lying. And so you can see geometric discontinuities.
And the funny thing about that is that we could fantasise a little bit that we were looking at sticker point,
and we don't believe that our unconformity represents the discovery of plate tectonics.
But really it's kind of those you may recognise this fellow and at least one person does.
That's James Ray for scale there. And and so the point is, is that really what we do is comparative planetary analysis for the first time.
And the analogue that we do draw a comparison with is and that is in the desert of Namibia where you
see ancient sand dunes that leave behind this dipping strata as evidence of the migration of the dune,
which is then deflated and overlain by a water rich deposit.
This playa lake deposits it's dry most of the time, but it does get wet.
And that turned out to be the signature of these sediments here.
These look like ancient sand dune deposits, and these looked like deposits that were formed in some type of apply a lake.
But the geochemistry of this place a week, that's something that Nick Tasca worked on, turned out to be very acidic.
And so this wasn't the perfect place to make a case for.
If life ever evolved on Mars, could it live in that environment?
That's what we mean by habitability. It's an existence proof.
If life evolved, could it live in the place that you just discovered?
And so here it's possible because some types of microorganisms do live in very strong acids, but it's not the perfect place.
But in terms of sort of the modern environment, this is what we drew an analogy with.
And this was something that I got exposed to in the year I spent in the Sultanate of Oman working with Bruce LaBella and others.
You go out to the empty quarter and this is a type of environment that we think we had on Mars at the time, generally very dry,
but once in a while it rains really hard in the Oman mountains and then 100 kilometres away that
that rainfall eventually surges to the surface maybe maybe decades later after the rainfall.
But it does get wet and then that water is there temporarily.
And when it dries out, it leaves its salts behind. And this is what we think happened at that location.
We discovered with the Opportunity Rover was a salty, acidic environment.
Okay. At the same time, that Opportunity was making those discoveries of these sulphate salts that were there.
There was a European space agency mission called Mars Express that had an instrument on it called Omega,
which is an imaging spectrometer that looks down at the surface of the planet.
And it went back to these same valleys that I showed the picture of with the steep wall rock.
And in this interior valley, which was very strange because there's just a closed depression here,
which then goes into one of these eroded bedrock channels.
And so this becomes a place where people imagine that maybe water gushed up and then ran out across the surface.
But with the higher resolution and. What people noticed was, is that there was a mountain in the middle.
It's just down in the corner here. It's that mountain right there.
And it's separated from all the rest of the rocks that go around the southern end of this enclosure.
And the cool thing about it was when they looked at it, they found the same kind of salts that we found with the Curiosity rover.
And so this is a perspective view, and this is about two and a half kilometres of relief here.
And the interesting thing about it is you don't have to be a geologist to recognise that this
stuff up here just looks different from everything that's down below this layer right here.
And it turns out that if you look straight down on it, that's what this map is.
And so this blue stuff that you see here is the top of the hill and the red stuff is the base of the hill wrapping around.
And these are two types of salts. This is a magnesium salt and this is a calcium salt.
And they have different solubility.
And it all adds up to a story where probably there was water, but it was very salty and it dried out and may not have lasted for a long time.
Okay. And so but for me, I think as a geologist in a stratigraphy and what was so exciting about this is
that this is really the origin of the study of compositional layering on Mars,
because with the imaging spectrometers, you're not just mapping textures,
you're also mapping the mineralogy of the rock at the same time that you map the textures.
And so the state of that art, if you will, is is not a lot different from the history of exploration in your country right here.
And I really love to draw a comparison to this, because effectively,
this is what William Smith did about 200 years ago when he mapped the layers of of England and was able to learn much about their composition.
And if you read the accompanying notes that go along with this map,
he realises that the discovery of these layers, these materials, will help fuel the Industrial Revolution.
The interesting thing about this, if you look at the layers in cross-section, they dip towards the English Channel.
And the curious thing is, is that they just stack all different compositions.
But this one here called Chalk comes from the Latin word creature, which means chalk.
And the important thing about that is this is a mineral name that follows the term Cretaceous to this day.
So in Earth's own geological timescale, there is a period which is actually associated with a mineral.
And this is kind of what we're doing with Mars right now.
And for those of you that are not geologists, the most important thing that he was able to do and followed up by his nephew was was able to
trace the layers because he was digging canals and he was studying the layers in the canals.
And he discovered that even though the composition and the minerals that are associated
with these different rocks would change sequentially as you went upward in elevation,
the fossils that you would see approximately follow the same order.
And so he was really on his way to discovering evolution, although he didn't know it himself.
But it fell to his nephew, John Phillips,
to basically put together the first time scale that subdivided the part of earth this we were most familiar with into three phases Palaeozoic,
Mesozoic and Coenozoic, because these are separated by major events in Earth's history that represent extinctions of organisms.
But this is kind of what we're doing on Mars, but without organisms, at least so far.
And so a geologic time scale is essential for us to to keep going forward.
With the lecture here.
It's a relative ordering of geological events, and if you're lucky, you get some absolute time constraints that tell you how old those events are.
So we have a correlate of rock property and it could be a succession of fossils.
Or like on Mars, we look at these reflectance spectra and we see minerals and maybe we can correlate these minerals around.
And then you combine it with some kind of a substance that you can actually date.
And on that basis, we build a geological time scale.
So here's our relative time scale.
And this is something that I worked on with a post-doc, Ralph Milliken, and we took all the different strata around Mars.
Don't try to read anything here. I know it's painful.
Just look at the colours. And what you're going to see is that the the the rocks that are shown down here at the bottom are mostly green.
Then they go on to mostly red and yellow, and at the top they're brown. That's all you need to know.
And that this is older and this is younger. And we're not exactly sure how old old is and how young young is.
But roughly, this goes from about 4 billion years ago to about 2 billion years ago.
And then after that, everything is brown. That means the planet's really dry.
But down in here is where people get really excited. And if you go to this place, you find lots of green stuff which are clean minerals.
If you go to this place, you see them as well.
But what was this one particular place really caught our eye called Gale Crater, where in principle you could go from green stuff,
what was thought to be just a little bit of it, then into the yellow stuff and then into the brown stuff or the green or clays.
The yellows are these sulphate salts and then the brown stuff is anhydrous iron oxide.
So that's almost like John Phillips is three divisions subdivision of the history of the Earth 200 years ago.
Okay. So that's a little bit of the background.
And now we're going to look at this place, this gale crater landing site, which is the place that the science team voted for.
And it's a fascinating place because, first of all, it straddles the Mars dichotomy boundary and this boundary.
What the dichotomy represents is low lands of the northern part of Mars and the highlands of the southern part of Mars,
with the steep boundary in between here. And so this crater actually straddles the boundary.
You can see the diameter of the crater here. It's similar to these other large craters, but these don't have mountains in the middle.
So what's so weird about this thing? It just sort of captured our our interest in our imagination.
And then it turned out there were other important observations about the rocks
that were in the middle of this mountain that resulted in us going there.
And I heard a lot of interesting debates and arguments about why we should choose this landing site or that landing site,
and it becomes a big mash up. And in the beginning, there were about 60 landing sites with hundreds of people contributing ideas.
And then in the end, we got the Final Four and it became a decision of our team.
And I had got to watch Bruce in action, trying to figure out how to drill an oil well on a line.
And at the end of the day, what I discovered was everybody was lobbying for their favourite prospect,
and the problem was nobody was listening to anybody else. So we had to change things around a little bit and then I had to go off and decide which
one of these things we were going to spend two and a half billion dollars drilling.
And in the end, the simplest argument to me was all the fancy spectroscopy aside, if you look at this landscape,
you can see all these channels that we've known about since the sixties and seventies.
We know that water runs downhill and the colour scheme here is topography.
So the whitest, the white colours are the lowest in elevation.
And the northern part of Gale Crater, with the exception of this crater over here,
is the lowest part of the planet for a thousand kilometres in any direction.
So if you want to make sure that you land the vehicle in a place where there was probably water,
that seemed like the simplest, least sophisticated explanation and we sort of went for it.
Okay. So this man in the middle is interesting and there's sort of two competing ideas.
One of them is that you filled up a crater and then you eroded it away to leave him out in the middle.
And the other one is, I call it the haystack idea, which is that they all started out flat like boles and the wind blew and in a
pattern that piled sediment on top of each other and built a mound in the middle.
But the authors of this paper mailing in Edgett argued that there's almost like
a history that can be observed in different craters where you're mostly filled.
And by the way, this is where the Opportunity Rover is. In the early days we called it Bird B, and then it landed and it got named.
But basically, it's it's exploring the plains just outside of this enormous crater that's completely filled up.
And then others look like they're starting to get evacuated, or alternatively, they're not completely filled.
And then as you work your way around in this direction, Gale represents sort of the number of what might be a continuum.
And it suggests that maybe it is the result of of erosion.
And it seems to be that that that is the case, that we're really dealing with eroded layers.
Okay. So it has the thickest stratigraphic section on Mars.
It takes us through those three periods, although we're only going to explore with the rover, the very old, the stuff back at the.
Time when they're supposed to be clays and sulphates. So here's our landing ellipse, which is about 20 kilometres in diameter.
And because it had a landing, ellipse was able to be shrunk down because of improvements in navigation and control of this of the entering spacecraft.
We were able to land in this mode.
And then the idea is that you land somewhere in the middle here and then you drive out of the landing ellipse and up to the mountain.
So we had to accept some risk that we might land on stuff that wouldn't be so good in order to drive a long ways to get the stuff that is good.
Okay. So again, just for the non geologists, the reason we're interested in these layers,
these these stratigraphic layers is because when you look at something like the stack of layers either at second point or down in the Grand Canyon,
they're really records of environmental change. And that's what we're trying to do is to to understand and reconstruct the environmental
history of Mars to see if it could have ever been a habitable place for microorganisms.
So the history of of robotic exploration on the surface,
it began with landers and on the Viking spacecraft they included some very sophisticated experiments to see if there was extant life on Mars.
And they all failed. They didn't find any evidence for life on Mars.
Congress didn't like that. And so for 20 years there was no funding.
And then eventually NASA's came back. And in the mid-nineties we landed the Pathfinder rover.
And the argument was, let's just accept that modern Mars is probably lifeless and get over that and think about
the ancient rock record when we see all the evidence for water that is now missing.
But in order to find the right rocks, you need a mobile platform.
And so this became what was known as a it's not these two these two rovers were associated with what were called missions.
This was called a demo because if it fails, it's not a failed mission and it's actually a true story.
And so the Sojourner Rover, six wheel, six wheels, four wheel drive,
the middle wheels are passive rocker bogie suspension so that you can drive over rocks that are
equivalent to roughly the diameter of of the wheels without tilting the deck of the vehicle,
which is paved with solar panels. So if you tilt away from the sun for too long, that's bad.
And so you don't want to have that happen.
And so this was really an experiment with one instrument on it that could make chemical measurements of the rocks.
And it was very successful. And so what happened was NASA got the go ahead to the next decade where we landed the Spirit Opportunity Rovers.
And you can see the heritage here. You have the same six wheel configuration with the rocker bogie suspension.
The solar panels are much larger than they were on this one because we had learned more about the dust accretion rate on Mars,
dust as always settling out. And if it settles out on the solar panel, you stop producing energy.
So you have some uncertainty in the rate at which dust is falling down.
So the way that you mitigate that risk is to double the surface area of it.
We don't add windshield wipers because NASA doesn't like moving parts if you don't have to use it.
And then what you see are the cameras up on the mast here.
Whereas for this little guy, the cameras were on the lander and the rover can never go very far beyond the lander.
But the idea now is for this thing to go off on its own. They were designed to last three months and drive 300 metres each.
Opportunity is still alive 12 years later, having driven 45 kilometres.
So it worked pretty good.
And then NASA's got the thumbs up to go ahead to the next decade because the goal of this mission was to prove what we had seen from orbit,
that there was this evidence for water. Once on the surface of Mars, we found that.
And now what we do is build a much bigger vehicle that has a lot of sophisticated instruments
to analyse the rocks for their their chemical content in ways that isn't possible otherwise.
Same six wheel configuration rocker, bogie suspension cameras up on the mast here,
a much bigger arm with a with a drilling rig at the end of it that takes us down seven centimetres.
And in the back, instead of the solar panels you have a swipe that at Cape Canaveral it just like the astronauts would get and
last what we do at Cape Canaveral with this thing is is put in the radioisotope thermoelectric generator,
which is NASA's code for nuclear and that goes in and that's our power supply and there's a thermal couple around it.
And so all the heat that is generated is converted into electricity and we generate
about 100 watts of power per hour and we have lithium ion batteries on board.
So we can store the excess power to the batteries and then run off the grid at Night-Time when we want temperatures to be cold for some analysis.
Okay. So a lot of people ask, why does this work?
Well, why have there been this sort of string of technical successes with these vehicles working as well as they do?
And what I learned in associating myself with these engineers is that there's no exception to this, that you test as you fly and you fly as you test,
and you don't build anything that you can't test rigorously and you don't do anything on Mars that you can't test first on Earth.
And as a result of that, things generally work pretty well.
What this engineer is doing is they have a little temperature sensor at the end.
The rover is being illuminated with a light source that has the same intensity that the sun does on Mars.
And they're trying to see what the temperature, what the skin temperature of all this metal is in response to that irradiation,
to see how well it matches to the computer models which predict the thermal behaviour of the rover because thermal expansion and contraction on Mars.
It's a. Degrees Centigrade every day.
And with all that titanium, copper and aluminium going back and forth, that's the that's the the surest way to failure if you don't get that right.
Okay. So we launch the rocket on day after Thanksgiving back in 2011.
Takes about eight months to get towards Mars.
And then eventually you enter the atmosphere and everything looks kind of like the rest of these missions.
But there were two big differences with the Curiosity mission.
One was the guidance and control system associated with the part where it enters the
upper atmosphere and it ejects some ballast and it becomes almost like an aeroplane wing,
which means it can then be controlled. And the onboard computer has a location where it's supposed to land and it's checking
departures versus the inertial guidance system and self-correcting for that.
That's why we can land in such a tiny ellipse. So we fly out of most of those errors.
Then it looks like the other ones were parachute deploys, the thing decelerates to subsonic velocities,
but then it gets totally different from any other mission that ever landed.
The heat shield falls off and there's what's called a powered descent vehicle that flies around on its own with its own propulsion system,
with the rover attached to the base.
And then when it gets to be about 50 metres above the ground, it wheels the rover out on a bridle of cables, and then the rover touches down.
The cables are cut, the descent stage goes off and crashes, and the rover is kind of born ready to go.
So it's what it does is it reduces the risk that we're rovers in the past would have to unfold in all these complicated ways.
If one of the devices doesn't work properly, the rover maybe may be disabled.
Okay. So it worked. And here's the first pictures we got.
And this was really exciting because the engineers here, all these semaphore tones and they know what's going well,
see people jumping up and down, but you're not sure why. And then this was one of the biggest battles I actually had with the chief engineer,
because the engineers what's happening is when we land, we plan the landing so that earth is still visible from Mars.
And then we transmit data directly to Earth that tells us about the state of health of the vehicle.
But then the engineers would like to have all of the data volume. But the problem is people want to see pictures.
And and so they don't believe that things actually landed.
And so the negotiation that I won was one picture, one black and white picture from one of the hazard avoidance cameras.
And so what you can see here 10 seconds after we land is when the picture get taken,
taken the lens cap is still the lens cover is still across the lens.
So that's all this dust that you see here stuck to it.
You see the shadow of the rover and then you get a glimpse.
We were wondering if that could be the mountain that we had stared at from orbit for almost ten years,
wondering if if we would ever make it there and earth sets, we get our data back.
And then what happens is 39 minutes later, a satellite flies over the same site and we're able to get more data.
The engineers, again, get virtually all of it, except for one more picture we're in,
which you can now see that the dust covers have executed their command to open up.
So you get a clear view. The shadow of the rover is longer by 39 minutes.
And there's no question that that our mountain is there and we just have to get over there and start climbing.
So that's all the data we get. And the rover lands at 10:39 p.m. and then the science team, the engineers that landed it,
go in a big party and they're unemployed and the scientists basically start working.
But the problem is we have to work on Mars time. And the annoying thing about Mars is that it rotates once every 24 hours and 39 minutes.
So every day it's like getting in an aeroplane and flying two thirds of a time zone westward.
And then you do it again the next day and the next day and the next day. And about every 40 days you come back in a phase with Earth.
You're away from your family. You're holed up in a hotel somewhere painting the windows black that you're supposed to be sleeping during the day.
And it's not much fun. But the great thing about it was there wasn't much to do.
And we actually all went to bed and we woke up the next morning and discovered this.
We had truly thought that nobody would be interested in this mission because soldiers,
this cute little toaster sized rover and Spirit and Curiosity are golf carts.
And we've got this big SUV and people are going to be bored with rovers.
But what we totally missed was in between opportunity and and curiosity.
Social media happened, and so we had a couple of videos that got released.
And when the thing was successful, it got it just got spread all over the world and everybody got into it.
But the great thing about it is this is what this is good because the taxpayers feel like they're getting their money.
They don't actually know really what science we're doing it, but that's okay.
So then what happens is that eventually the data comes down,
but you need to wait for a very high bandwidth handshake with the orbiters that are going around Mars.
And we took a 360 degree panorama with our cameras.
And we were also interested in the mountain, in the metal that we had forgot that the crater rim itself has its own fairly imposing mountain ranges.
And so this this is about two and a half kilometres of elevation between where we landed,
which is this really boring spot that looks exactly like every other place a rover has landed on Mars.
But the difference is you don't have to drive very far to get the bedrock.
And so that was a cool thing about it. So the Sky Crane actually worked really well.
It kept the rover away from all the interesting rocks that we landed on, this sort of featureless gravel plain with a bunch of grey rocks.
But in the background, what we wondered was what were these layers?
Because that was the whole reason that we were going there.
So then eventually the rest of the 360 degree came around,
and now we got the first images of the foothills of Mount Sharp, and we decided that this was better than the crater rim.
And the important thing, what you're seeing here is that these layers from orbital show the data later or the interpretation of the data later.
But these are all the things that showed these spectra for hydrated minerals.
And that's important because it means that these rock layers formed in the presence of water.
But we just have to drive across here about ten kilometres to actually get to the first rocks.
Oh, yeah. No, here's, here's the slide. So here's where we landed right here.
And this is where we need to go. In fact, we need to go all the way to this brown stuff.
And honestly, we're about 200 metres away from it five years later.
But the original goal was to land blast over here and start getting into all these these layers.
But as you can tell, we got we got waylaid.
And in fact, rather than drive directly towards well, we had to drive through these sand dunes that you see here.
That's why we had to we couldn't go this way. We had to drive all the way around and come through right here.
But we actually drove in the opposite direction.
So I need to explain to you why we did that, because it turned out that we sort of hit the jackpot there.
So this goes back to the mapping that we did before we landed. And again, what you're looking at here is it's a plot of topography.
So these are lower elevations and the reds are higher elevations.
And and here's where we landed. This is our landing ellipse.
Again, it's 20 kilometres in diameter. So we landed slightly off centre, which is which is pretty good after going 300 million miles.
And the landing ellipse is just in front of a feature.
Not exactly the best developed thing we ever saw, but the geologists had pretty good agreement that there was a alluvial fan that represents a
sedimentary deposit derived from erosion of a channel back up here that cuts into the crater rim.
And so the hope was that since we were basically landing downhill of this feature that showed evidence of water,
that maybe if we did find rocks down in this area here, they would have something to do with water.
That was very important because our primary objective is out here.
But if we land a break a wheel and can never get over here,
I had to reassure the space agency that that we would actually have something to do here that would be worthy of the of the mission.
So we did a lot of this mapping. Here's a different map.
The plots, a property called thermal inertia. And the way to think about this is if you're not used to it, is it you're you're downtown.
And it's a cool fall day and you walk past a building late in the afternoon and you feel the heat radiating off at you.
That's what's happening here.
We're making observations at night from an orbiter looking down at the ground of heat being emitted in the thermal infrared spectrum.
And so everything that looks like it's red here is just generating more heat than than than the material that's next to it.
And it was interesting to us that the the highest density of these red patches were out in.
Of this feature that we consider to be alluvial fan. And it led to two frontrunner hypotheses for what that might be.
On one hand, maybe there's a lake deposit that's there,
and everybody that wants to find water on Mars will be very happy because we'll see cemented
rock where the cement derives from soluble minerals that precipitate from the water.
On the other hand, there, the people that have been looking at Mars for decades,
they're are convinced that the reason this thing is emitting so much heat is because it's a black lava flow.
And that wouldn't be so good for two and a half billion dollars.
I mean, it'd be great to do the geochemistry of the lava, but that's not the first priority for the for the mission.
And so this went back and forth, actually, and it was it was pretty tense.
But what you can see is that your land here and when we realised and we plotted our location, we realised that's where we were.
We just decided that for a 500 metre investment of driving in the wrong direction, we could check out some of this red stuff.
And so we dug in actually we did this mapping before we landed and and we made up kind of a surface materials map based on the textures.
Here's this alluvial fan that we talked about.
And then just based on the texture we have fractured light tone, terrain, cratered, surface, smooth, honky rugged.
They're all sort of intuitive in terms of what you would see there. But here's where we landed.
We actually landed on the smooth, murky terrain. And then this fractured light tone terrain exactly coincides with that high thermal inertia material.
And then the cratered surface over here looks like something you'd see on the moon.
And so here it is. We decided to go and check it out, because for a geologist, if you get to this point right here, you've got a three fer.
You can sample all three of these rock types. And even if they have nothing to do with water, it's still going to be cool.
Okay. So two days after we landed, the high rise camera flew over and took a picture of the landing site.
And here you can see curiosity for scale. And curiosity is two and a half metres long.
And this very high albedo, this very bright thing that you see in the middle of the butterfly wings here, that's the rover itself.
The butterfly wings are actually where the rocket motors blasted the soil away and exposed the bare red bare bedrock.
The dark patch that you see here is where the dust was blown away from the area.
And then this is sort of the unadulterated background, smooth, murky terrain, the cratered terrain and the light tone, fractured terrain.
And so our goal was to basically drive and explain this to NASA.
So five football fields and we'd be there and we had a list of hundreds of names that we had to choose from.
And so we had to give a press briefing. And I was in a bit of a hurry.
So I told the team, Somebody, please pick a name.
I don't know if you guys know Kevin Lewis, but he came up with this name Glenelg because it's a palindrome.
And so it was reassuring that we'd get the same thing when we changed our direction.
It went from backward to forward, so that was the reason that we picked it.
But Glenelg Scotland actually picked up on this and you can Google it and they now celebrate Mars Day once a year they adopted it.
Okay, so when we got there, we drove across this terrain and then we got out onto these.
You're going to see a picture from the ground of this ledge. Okay.
Here's the ledge. And this is us crossing the boundary between the smooth hammock terrain to the light tone, fractured terrain.
And basically the light toned fracture terrain is solid bedrock, just covered with Mars dust.
And this stuff has some gravel and and chunks of rock and stuff like that, windblown sand.
And that's what sort of smoothes it out. So the great thing about it was, is that when we got here we realised that we really did have solid bedrock.
And the question was, is it a lake deposit or some kind of sedimentary deposit or is it a volcanic igneous rock?
So we drove down in there and we got close enough and right away things started to get pretty interesting.
First of all, the rock is cut by fractures that are filled in with some light tone mineral.
And we have an instrument that's a laser and we hit it with the laser, got the spectrum back in it, showed it to be calcium sulphate.
Another thing about it was this rock looks like it's got a bad case of the measles.
There's all these bumps sticking out of it that geologists call concretions.
You can see them down here where they're merging. And these things ultimately turned out to be quite high and magnesium and iron.
It turns out that they're a carrier of clay mineral.
So then the time came, we decided that this was a great rock and we wanted to drill this material and see what it was.
Mineral, logically. So we drilled the hole and this is what it looks like.
And what you can see is that those same white tone things that you saw on the surface, they run down the three dimensional.
They are filled fractures. Here is the array of points where we shot into the hole with the laser.
And this one up here hit some of the white stuff. And so we got confirmation that that was calcium sulphate in the third dimension.
And then we also began to again see that there was some enrichment and magnesium and iron.
But the problem is, when you look at the chemistry of this rock, it's perfect basalt.
And so all the people that wanted it to be a lava flow, it's kind of like the spoiler really wants to win.
They're like, it just looks like a lava flow. But the problem was when we drilled it and we did the mineralogy, we got something really different.
And so Rocknest is a modern day Martian soil that we analysed with a bunch of unaltered, basaltic rock fragments in it.
And these are all the minerals that make up a rock for the geologists called basalt major minerals.
And and here they are in their normal abundances.
And then here they are in this in this hole that we drilled.
And you can see how they're all decreasing in importance, especially this one called olivine, which almost goes to zero.
And then we see the appearance of a clean mineral called Smectite, which is actually an iron magnesium smectite.
And this only forms in water and it's in here at the 20 to 30% level.
And then there's another mineral, which is a very minor component of of the soil, which turns out to be an important component of this rock.
Nick Toscan and his group have been doing a lot of work on this,
and this is also a very important constraint on the fact of this rock representing an altered deposit.
I'm going to show other pictures later on of of some even better lake deposits than this one.
But our interpretation was that this was an ancient lake deposit.
Okay. I want to explain some of the data from the most sophisticated instrument on the rover.
It's called SAM, which which stands for sample analysis at Mars.
And what you do is you take the rock powder, you drill the rock powder,
it goes down into the rover and and then it goes into what's called the sample manipulation system into one of these these quartz cups.
And then that quartz cup goes into an oven and we heat it almost up to a thousand degrees centigrade.
And in cooking it,
we release all the volatile materials and we collect those gases and then we analyse them in this spectrometer that we can feed it off.
That way we can close a valve and send it down to a different kind of a spectrometer.
Tuneable laser spectrometer. This actually allows us to determine isotope ratios of, of, of, of water as well as carbon and oxygen.
And, and then we can turn another valve and send it across something called a hydrogen carbon trap, which is super cold.
And then all the gases condense and then we can turn the valve again and heat it up
and then liberate those gases and put them into something called a gas chromatograph.
And from that, maybe get a sense for what organic materials might be present on the surface of Mars.
So here's what the data looks like as it's processed and comes out.
This is the intensity of this quadrupole mass spectrometer.
This is temperature rising from about 250 degrees C up to about 800.
And the first thing that happens is we produce a lot of carbon dioxide, comes out of the rock.
There's a lot of water that gets produced. There's oxygen that comes out the carbon dioxide peaks.
And then after that, the water peaks and then the water production drops off until you get up to about 700, 750 degrees centigrade.
And then the water abundance comes back again.
And what's happening there is that in this clay mineral, like clay mineral has water in it's mineral logic structure.
You're liberating that water. And it turns out we can actually capture that water and analyse it with the Tuneable laser
spectrometer and get its isotope ratio so we can measure the isotope ratio of water in Rock on Mars.
That's almost 4 billion years old. And then this stuff down here, these are two forms of sulphur that come off sulphur sulphate and sulphide.
And so this was very important in giving us an interpretation of the rock.
I won't go into the details, but it can be simplified into a convenient story of pictures.
And, you know, ten years ago, well longer than that.
Now, this is what we got with opportunity. We found this wet environment and we were led there by a signature that we saw from orbit.
And we didn't have a drill, but we had kind of a rasp. And when we rubbed, the rock erodes away.
And the powder that is produced is red and the rock itself is red.
And it turns out this is associated with a mineral called Haematite. And we think that Haematite formed in water.
But the important thing is, as Nic was able to show with this postdoctoral research, this was super salty and very acidic.
It just wasn't that good of an environment.
When Curiosity drilled this mudstone, you can see that Mars is still red on the surface, but when you scratch below it, you now get a grey rock.
And what that means is that the iron in that rock is not oxidised like it is here.
It's actually more reduced. It's in this mineral called magnetite.
And so these are two rocks from a similar kind of environment on Earth.
It's a Triassic rip basin from Connecticut.
And then in New York, Boston and Washington, D.C., you have brownstone buildings that are brown because of this.
There's these kind of red sandstones. And then you have Grey Rock, which is less interesting.
But the Grey Rocks are the ones that preserve the organic matter. So we got really excited about this because we have a much better chance to
preserve organic materials on Mars in this kind of rock than this kind of rock.
So the opportunity, if you reconstruct what Mars might have been like at that location, this was our favourite analogue.
It's a it's a place called Rio Tinto in Spain,
and there's a massive iron sulphide deposit which is being oxidised and weathered and all that sulphide gets converted to sulphate.
It produces a huge amount of hydrate of sulphuric acid and that the acidity is so low that iron is actually soluble.
And so the Rio Tinto because iron is actually in the F plus three state but dissolved
in this water and then this material that you see and crusting these rocks here is
a sulphate salt called jarrah site and you put that together and this is the stuff
that made up these rocks that Nick documented back at the opportunity landing site.
There are microbes. That grow there, but it's a very specialised group.
So it is possible that this environment is habitable.
But the reason this environment is habitable is because this is not that salty.
It's salty, but it's not that salty. The rock on Mars was far saltier than seawater.
And and we think it was actually an uninhabitable environment for the same reason that honey keeps on your shelf.
Honey is an aqueous environment, but bacteria don't grow there because the water activity is so low.
So that was kind of the bummer for that site. It wasn't the acidity, it was the salinity.
This is kind of what we think we discovered with curiosity. Just take these higher grasses away.
We don't think they were on Mars. And this is actually drier than what we think we had.
These are these are prior weeks. They dry up seasonally.
But it doesn't really matter, because what happens is if you just dig a shallow hole, the water is still down there.
So even if the surface is dry, there's it's still saturated down here.
Microbes grow really well because this is this rock called basalt, which weathers in place in these lakes to form these iron,
magnesium, smectite minerals that have a very similar composition to what we found on Mars.
Okay. So this is what it comes down to.
We don't think that the honey was a habitable environment and what we think we found was
sort of like a rock battery where microbes that that actually harvest chemical energy,
just like the chemical energy that's stored in a battery you can stored in a rock and you just need iron in two different oxidation states.
We found it and you just need sulphur and two oxidation states.
And we found that as well. So a microbe could have been very happy in this environment.
That doesn't mean they were there, but it's it supports the case, too, to look on in the next decade.
And now NASA's planning the next mission. So here's what we discovered with the organics.
It turns out to be very difficult to do this on Mars. And I'll explain why in a minute.
But I mentioned that the first thing we did was to scoop a soil.
And and so what we're doing here is plotting the abundance of a compound called chloro benzene.
This is the most sophisticated molecule that we have found.
But it turns out it's it's distributed in a in a very distinct way.
So this is the detection limit for the instrument.
So, you know, there is some positive value here, but we don't think that it's we just think it's noise.
So we don't think there's any of that stuff in there. Then we drilled this first hole.
Remember, here's the you can see the spots from the laser, here's the the sulphate filled fracture and we drilled it.
We didn't find any of that stuff.
But then we drilled another hole with a hypothesis that if we go to the highest concentration of all the concretions,
maybe the concretions are preserving something that got destroyed everywhere else.
So when we did that, this is where we found it, and it's statistically significant that those molecules are there.
So their absence here really suggests that these organic compounds are somehow related to Mars.
So to be sure that before we published the paper, we then went to the next rock type, which was a cross bedded sandstone,
where we didn't expect to see much of this stuff and indeed we didn't measure it of it,
which which means we're not we're not even passing it forward as contamination from the previous drill hole.
So we don't really know what this means when it comes right down to it.
We're not even sure that we're not manufacturing these when we heat the rocks up by taking other organic
matter and taking chlorine from Mars and then combining it together to manufacture this synthetic molecule.
We're just not sure.
But the fact that there's an abundance of it here suggests that it's worthwhile to go back and collect this rock and return it to Earth.
Okay, so we got all excited.
Have a special issue of sites where we publish all our papers and this is all location of the drill site that made it on the on the cover.
And I was up at at HQ and we as a team were presenting these results.
It was in in December of 2013.
So the cool thing about it was the mission is funded for two years and you get two years to basically discover something that validates the mission.
And we found that after just six months and it just took us a while to to work up all the results.
And so all this stuff was found here in a place we call Yellowknife Bay.
And then after that, we hightailed it. And the idea is to drive as fast as you can over to the good stuff.
And then we stopped at Kimberley in the blue. These blue circles represent where we did our first drill holes.
So this is where we drilled that cross bit of sandstone and we waited to make sure there wasn't near the core of benzene
in that hole so that we can make the argument that what we did find in the hole back here was really indigenous to Mars.
But as we were driving along, we discovered that this smooth hammock terrain actually wasn't so smooth in harmony.
And literally we had just presented the results and and the mission manager called me up and said, you need to come back there.
There's, there's a problem. And so we're going to stop driving.
And so what you can see here is in these images that a sol is a day on Mars, 24 hours and 39 minutes.
And after 400 of these days, we had picked up a fair number of things in tents, and we expected to see that.
But we didn't expect to see was this tear that you can see over here.
And so we went back and we started to look at all the terrain and we're trying to figure out how in the world that this will get damaged.
So what we did then was we aimed the cameras at all six wheels and we rotated all six wheels and took a complete set of pictures,
and we discovered that it was actually much worse than that.
We had realised these holes are supposed to be there,
this array of three wide spells in Morse code and it was clever engineers and this whole just is bad.
You're not supposed to see daylight through on their side there. And that brought the mission to a grinding halt.
And we hadn't really made it to the place where we're ultimately supposed to be going, but it took us about six months to work through this.
So here we catch the culprit in the act. And and what you can see is that we're driving over these rocks that have these sharp pointy edges.
And it turns out that the wind is howling in this place that we landed.
And it's turning all the rocks into pyramidal shapes that geologists are
familiar with in places like Antarctica and other deserts that are very sharp.
And the wheels honestly were just under engineered.
They just they just couldn't bear the strength. And we didn't expect to encounter this many rocks.
And the wheels were made to be lighter than what you might have wanted to do, because that helps with the physics of the landing problem.
If the rover weighs less than the than the master vehicle does.
So we we did some tests and we divided up.
And I went off with all the scientists and we tried to figure out how can we get less of these rocks?
And the chief engineer went off with his group and they did some experiments.
So here you're going to see the results of these. See?
Okay. So we call this thing the inhaler. And so we're we're basically driving the vehicle across it.
And and what's happening is this the pivot point for the wheel is in front of the lever.
And so what you're trying to do is basically push this thing across horizontally,
which not only gives the static load associated with the acceleration of gravity on Mars acting on the Impaler,
it gives you a dynamic pressure of pushing into it. So the idea became, what if we drive backwards and pull the wheels behind us?
It's actually basic physics, but it took us six months to figure this out because we had to do all the testing.
So here we are now. Same thing, but driving backwards.
So it worked. Okay. So that's the first part of the problem.
Let's drive backwards. So we made the decision that we would now drive backwards as much as possible.
You get four wheels that are trailing instead of four wheels leading.
So there's still two that are going to get pretty badly damaged. And then this is the part that I worked on.
Here's where we stopped. And the black line that you see here is the route that we're supposed to be taking,
which is effectively the shortest distance between point A and point B,
avoiding some of the craters in the sand dunes that you see here and then adjusting for other things that look like scary terrain.
And then so what I do is I chose let's see, one, two, three, four, five, six,
seven different scientists on the mission who I think have the most experience with thinking about terrain and geomorphology.
And I give them all the data that they want and they get a week to go away and come up with a preferred route.
So how many times have geologists ever seen this before? Seven different interpretations.
And the reason why is because there is no hypothesis.
It's just guessing. And so some people say, let's take the high road.
Other people say, let's take the rover. Some people will say, here's the guy.
The green path is basically saying, I don't care. I'm still going with the shortest route.
And then the pink guy over here says, let's take the longest route,
because that goes through the valleys and maybe the valleys actually have more sand and less rock.
So that was a tough sell to Nasser. We turned out to take the pink route because I'll show you why in a minute.
But the NASA's lead engineer is saying, let me get this straight. You guys are going to take the longest route to keep the wheels safe.
And and so we had to do a little bit more work before they accepted it.
So we what we did was terrain mapping. So we actually blow the images up to their highest resolution and subdivided it into a whole bunch of
terrain types that that we interpreted to have properties that would be worse or better for the wheels.
So what you can see here is that basically we're trying to stay on the green or the blue and the green or are ripples
where we can see alien windblown sand from orbit and the smooth looks like it should be some kind of of sand or soil.
But what we're really trying to stay away with are these cratered, capped rocks.
And originally we thought we'd be better off driving on the rock to stay out of out of the sand.
So the first challenge. Gosh, it's just off screen.
There's a gap up here that we had to drive through and to make it into this this network of valleys.
And here's what this gap looks like. So what you can see is, is Rocky Plateau.
These are all conglomerates and sandstones heavily cemented.
And then here they are shedding all these sharp rocks down that we've been driving across.
And there's a valley right here. But the problem is the valley is is occluded by a single sand dune that bridges across here.
So the problem is we have to make it across the sandstone,
across the sandstone in order to make it down into a valley, which we think is good, but we don't know it's good.
So the NASA guys are all saying, you know, how do you guys how are you guys going to demonstrate this?
And so we said, well, the first thing we should do is just go up to the edge here and put the front wheels
up here and peer over the top because our camera is kind of like a periscope.
So here we are peering over the top and and you can see why you wouldn't want to go racing over the top,
because this this cliff is collapsing to produce all these blocks.
And if you drove straight across, that would really be a problem.
But what you can see in the distance here is that the terrain really does look pretty good, like what we had thought we were seeing from orbit.
You know, there is some ripples. And then down here, you can see some rocks strewn around.
But altogether, this this sort of sandy river looks a heck of a lot better than than any of these other options that you see here.
But the problem is now we're worried about getting stuck in the sand dune. So here's here we are doing doing an experiment.
And this is an animated gif that shows 24 hours of data.
And what you can see here is that we did literally come up to the brink and
we put the left front wheel just on top of the crest line of the sand dune.
And then the right front wheel is just behind it because of suddenly we think we can still pull ourselves out.
That's the idea. But what we do is we drive the vehicle up there and then we took a picture and
then we wait 24 hours and take another picture at approximately the same time.
But it wasn't exactly the same time, and that's why the shadows are a little bit different.
But the important thing is you can see the shadows moving, but what you can't see moving are these little fractures in the sand dune or the wheels.
It doesn't look like we're sinking. So with that, we eliminate the risk.
Not completely, but you know that the mobility engineers are going to always invent every worst case scenario that could possibly happen.
And so in this case, it was, yeah, there's beautiful sand here,
but one centimetre beneath it is going to be baking flour and it's just going to sink in any way.
So we got up the courage, we drove across it, it worked well, and then we looked back at it.
And so here's our tracks and what you can see.
Doing what we're doing here is driving over the crest line and we command the vehicle to your on purpose.
And so we overdrive these wheels which steers us away from sliding down the front here and skidding into these rocks.
And so we get most of the way down. And then you can see where we made a little trench here that comes from a wheel wiggle that
we do to make sure that we've estimated the slip rates correctly and then we just drive on.
So that's what we did.
And we made it through there. And and we've been doing fine ever since.
And here's where it took us. Eventually, we finally got to the place where we had told everybody that we were going to go to.
And we're descending down to a place that became known as Army Ghost Valley because the guy on duty
worked in Death Valley and suddenly we had Death Valley names and this was this rock that from orbit.
It just doesn't show any signatures of of hydrated minerals.
It looks like it's going to be pretty disappointing.
But what we had learned from our first drill hole is that that place didn't show any signatures either, but it had 20% clay in it.
And this was a big surprise to the Mars community,
because these rocks are relatively younger and the history of Mars, and they're not supposed to have all this.
Clay And so the question was,
could we demonstrate that again as we drove even higher up into the stratigraphy of layers and this became our chance to do that.
So we worked along. And again, just to give you the frame of reference, that image that you saw here, these are the propels.
We were parked right here looking down into this Ahmed Gusev Valley.
And then ever since then we've been drilling and we've got three or four more drill holes that I haven't plotted.
But conceptually, this is what we learned as we drove the vehicle uphill.
This is a plot of elevation. And and this is the small number that that we drove across.
So here we saw 400 when we had all these problems where we tore the wheels up because we had basically driven only a short way.
And what we interpreted to be sandstones river deposited is sand that becomes a rock.
And then we drilled into a mudstone and then we drove across more sandstone and tore up the wheels.
And then we learned how to drive around it.
But we kept going uphill and all the rocks that we had been looking at look like the kind of rocks that form in an ancient river or delta.
And then right around saw a hundred. We crossed a geologic boundary that we could see from orbit.
And ever since then we have been in what looks like a lake deposit,
and now we've got it accumulated about 150 metres of that stuff and and we drilled as we went along.
So this is sort of for the geologists in the room. And I'll just leave this up here for just a minute because it's it's probably going to be our our
greatest accomplishment is the is the mineralogy that will distinguish us from previous rover missions.
And what we're really interested in are these kinds of things with the brighter colours that you see down here.
These were the holes that we drilled originally, and we wrote our science papers about this green stuff in here.
It's missing from the legend. That stuff is missing.
This is this iron, magnesium, clay. Okay, so every place you see the green means we have this iron magnesium clay.
The black stuff is the magnetite, which we think somehow is forms in association with that clay production.
And Nick Tasca has some good ideas. So we left those rocks and when we got to the hills we found more clay.
But we now had haematite in addition to magnetite, and we had some of these less common sulphate phases that you see down in here,
especially this iron sulphate which actually now suggests we're getting into some acidity that we didn't have before.
But then something really dramatic happens when we go up to these next.
We get up higher into the section, most of it the haematite goes away.
Then eventually it goes completely away. All of these acidic sulphate minerals go completely away and we have a large amount of crystal and silica,
mostly in the form of crystal light and tritium.
Right. And so we actually think that there might have been some, some felsic igneous rocks that were contributing detritus to the basin.
But the biggest part of this is actually amorphous silica that I'll show you in a minute.
The thing is, is that even though it looks like we stay in the lake,
the chemistry of this lake and or its subsequent die genetic history are changing.
And so the place where we have been most recently actually has the most clays that we've seen of the entire mission.
But now we don't see any magnetite and we've just got a lot of haematite and we're picking up a lot more sulphate,
but we've never seen magnesium sulphate and we actually have picked up mostly gypsum.
So this looks surprisingly like the earth actually.
It's just it doesn't look like that weird stuff that we found 15 years ago at the Opportunity Landing site.
So these are what these what we interpret to be these lake deposits on Mars.
You can see the scale bar here. These are centimetre scale, sort of almost rhythmic looking deposits.
And if you compare them to to ancient lake deposits on Earth, these are from Canada and these are glacial deposits.
This is actually a drop stone there. We haven't seen anything that looks like a drop stone.
But the fact is, is that they're these are exactly at the same scale.
And so it's surprising actually how similar that seems to be.
And then this is what happens where you get this very high silica rock,
this fabric that you see angling down through here is something created by the modern day wind eroding the rock.
But if you look behind that, you can see very, very fine lamination in there.
And you can also see that there are these these dense, that these what we think are voids.
Because when you trace the surface of the rock around, there's a lip like a ski jump right here and you can see the same holes in that.
So we think those are three dimensional features of the rock.
And in conversations with Nic, what we're wondering is this rock is basically mostly amorphous silica,
a little bit of crystal and silica and a lot of magnetite.
And Nick has come up with a way to possibly make hydrogen in this reaction.
And it could be that these these are bubbles, gas bubbles preserved in the ancient rock.
So if that does, it's the case. In talking with Ray today, you know, hydrogen turns out to possibly have a capability to keep Mars warm.
So maybe we're now converging on a on a solution for the early climate of Mars.
So this is a paper that was just accepted yesterday into science by Joel Horowitz,
who was a fellow graduate student with Nick Tasker that expects to explain how you had a link,
but it wasn't all the same thing and it seems to have changed through time.
And here's the rock that has this very thin lamination that looks more like a magnetite silica facies.
And then here's a rock over here that has more of a haematite file, a silicate association.
And I think in the interest of time, I'm not going to offer a more detailed explanation of that,
other than to say that we think that it has something to do with mixing of ground waters with surface waters,
possibly in the presence of of UV light that might create oxidation to generate acidity in order to explain this.
But if you get deep enough, you don't see any of the acidity and maybe you have a more reducing environment.
It's not really similar, but it is kind of haunting to think about the early history of the Earth.
When we deposited a rock called Banded Iron Formation,
where you see what's of silica fine lamination and associated with iron oxide, it's mostly haematite.
But the fact is this is not entirely different from what we're seeing on Mars.
And there have been a number of explanations offered for these rocks, but.
I'll just leave you to think about that.
And as my last slide, I think that as we look at Mars, we're really beginning to do comparative planetary Scientology and geochemistry.
You really have to get a Ph.D. in geology and geochemistry two to take apart Mars now.
And what you wonder is what about all the exoplanets where people are finding all these other possible habitable environments?
And so I think that it's all all looking pretty exciting.
So thanks for listening.