Iceland.
A harsh Nordic landscape where fire meets ice.
A country of volcanoes, glaciers, waterfalls, and expansive tundra.
And for some, the perfect analogue environment for informing NASA’s search for life on
Mars.
Meet Dr. Amanda Stockton, the principal investigator of FELDSPAR: the Field Exploration and Life
Detection Sampling for Planetary and Astrobiology Research.
Dr. Stockton and her team have been traveling to Iceland to conduct sampling missions in
a volcanic environment with striking similarities to the Red Planet.
If you’re thinking about Mars, you’ve got CRISM and other orbiter instruments that
can look down on the surface.
And when it looks down at the surface you basically see one pixel, and that pixel is
all the same color; but that pixel can be a kilometer by a kilometer across.
So we go out to field sites in Iceland where we’ve got that kilometer by kilometer and
we go and we see: how many samples do we need in order to actually represent the whole area,
and how far away do they need to be spaced.
This year, what was really cool, is that we went out and looked at different colors of
pixels.
We want to go in and see how life varies as we go across the different colors and that
helps us figure out what pixel do we want to land in whenever we go looking for signatures
of life.
Traveling to the field site is quite challenging.
The expedition begins in Akureyri, Iceland, where the team has setup their field laboratory
at the local university.
Dr. Stockton and her team will drive six hours over sand, rock, and road, completing three
river crossings before they arrive at their campsite.
Operationally, it’s quite challenging to get to this field site.
The logistics involved are a little intense.
That involves lots of river crossings, and dirt roads, and sometimes sandstorms and dust
devils, and all kinds of fun weather.
They’re not nearly as bad as Antarctica, but it’s challenging for your ordinary tourist,
which makes it particularly wonderful because we don’t have all of this anthropogenic,
human-caused contamination of the site.
But eventually, we get the samples that give us the science that we want.
At 4am the following day, the expedition team rises and heads to the field site.
It is 5am.
Our whole work started because of the NASA Nordic Astrobiology Summer School.
It was an incredible experience and as part of that school, some of us got a taste of
field sampling.
Those of us who realized how important this area was to places like Mars, started thinking,
‘boy, this would be nice if it wasn’t just part of a school for education, but if
we could actually get some real data to publish some papers, and since that time now, we have
some new members of our team.
And we sort of kept it young, early career people though, which I think is really neat
because it sort of sprung from a grassroots educational outreach thing that has now become
a real scientific endeavor, and it’s so fun, I feel so lucky to be a part of this.
Right now we’re trying to get mapping so we can get a three-dimensional model of the
entire area on this side.
The quadcopter is going to fly up and it will take pictures in a line; not directly down,
but off at a little bit of an angle.
That offset, plus multiple images, is what can give us a three-dimensional model of the
entire terrain.
We’ve already got a decent model for the other side of the volcano, and that’s where
they’re sampling today.
We’re Team FELDSPAR, we’re a group of astrobiologists from Georgia Tech and NASA
and a couple of different institutions.
We’re here at Holuhraun, which is a 2014 eruption site in Iceland.
Because of the geochemistry of the place, it’s a decent analogue for certain regions
of Mars.
And, more importantly, for our purposes, there’s almost nothing alive here, even down to the
microbial level.
And it’s actually surprisingly difficult to find places like that on Earth, because
life is everywhere.
So that makes this a really good place to test certain ways for looking for very small
amounts of life.
One of the big questions that NASA wants to answer at Mars is, whether or not it is inhabited.
Whether it had life at one time, or has life today.
Now, one of the things that we can do here in Iceland is help to test that theory.
Iceland is one of the most volcanically active places on Earth, and a lot of the properties
of the basalt and the other volcanic rocks are really similar to what we see on Mars
and what we’re doing here is trying to see how life colonizes a fresh lava field.
What moves in first?
What comes after it?
How does that process happen?
And we’re hoping that this can help us find those places on Mars where we’re most likely
to find life.
Our team has sort of a two-pronged approach to sampling.
We collect some samples here that we will then analyze in a field lab, or in a lab back
at one of our respective universities.
But we also try to do some in-situ science, too.
In-situ means doing it right there, right now.
Of course, the biology samples are the most important not to contaminate, so we collect
those first.
Today, we took samples in nested sampling grids.
One of the key things we want to look at is how much variation there is point-to-point
at different spatial scales in the types of signs of life that we might look for on other
worlds.
There are a couple of different biomarkers that we look for.
Biomarkers are traces of past or present life.
One of the key ones that we look for is ATP, which is a molecule called Adenosine Triphosphate.
It’s a very convenient store of energy, molecularly, inside a cell, and so it’s
involved in almost every metabolic reaction that every cell on Earth does.
Is that correlated in any way with the types of geochemical measurements that you can make
either on the ground or through remote sensing before you get there?
Because what it all comes down to is: so you’re a rover.
You’ve landed.
You look around.
What’s the first test you should run?
If you don’t see anything, should you move?
What’s the second test you should run?
And it’s all down to trying to get the most science that you can out of a mission to Mars.
Once the biologists have collected the samples that we’ll be studying to look for life,
then the geologists and the chemists can go in with our instruments and get the composition.
We will have the team that’s looking at biological analysis go first, and then we
will come through and use the ASD to look at the minerology of the rocks that they’re
sampling.
MRO, the Mars Reconnaissance Orbiter uses instruments to look at the, particularly what
I’m interested in, is the composition of the surface of Mars.
So, when we look at the composition of Mars, we use CRISM, which is the Compact Reconnaissance
Imaging Spectrometer for Mars.
It looks in a certain wavelength range, which is the visible and near-infrared, or VNIR,
to determine the composition of rocks that we see on the surface.
So, we are using a visible and near-infrared spectrometer that is handheld, that gives
you similar information as we get from CRISM, but obviously closer-up, which allows you
to see different absorptions within the visible and near infrared spectrum to understand the
mineralogy or chemistry or the rock that we’re looking at.
A lot of the field instruments that we’ve brought with us, we’ve brought because they’re
very similar to some of the instruments aboard some of the Mars rovers, for example, Mars
Curiosity.
I’m basically the ‘human rover’.
I have all of the instruments that the rovers have, not all of them, but the instruments
that I have mimic the instruments that are on the rovers.
So, we have the ASD, which you’ve already checked out a little bit.
We also have the XRF, which is an X-Ray Fluorescence spectrometer, So, we can get compositional
data about the rocks.
The combination of these tools tells us more about the geology; that’s what this project
is trying to do is link what kind of biology would you expect based on the geology and
all of the other various environmentally things that we’re going to try and measure, as
well.
So we now have our samples back in the lab, and everyone that comes in this room has to
wear a facemask so we do not spray all of our bugs on the samples when we talk.
And it’s very easy to forget that when you’re walking around in the lab, so even though
I’m not currently working with the samples, I still get the facemask.
So we brought our samples back to the lab, and we laid them all out on the table so that
we could get an overview of the physical characteristics of the samples and see all of them laid out
together.
The thing that we need to do that’s very time-sensitive is to look for ATP.
Because the ATP profile of what you get out of the cells changes very rapidly once they’re
pulled out of the field environment.
So we’ve brought the samples back, they’ve been stored in the fridge overnight, and we
are now preparing to do extraction.
We take small amounts of those samples, drop them into small baggies and double-bag those.
That goes over to the Thor station, where the geologists bang on them with hammers to
break the big chunks up into little chunks.
After that, we’ve got a fine-grained powder that results from all of this processing.
That goes over to another station where 500 microliters of powder is put into little micro
centrifuge tubes.
And that’s where we’ll end today.
That’s a lot of samples.
Tomorrow, we’ll come back, we’ll add 1 milliliter of buffer to each one of our little
tubes that has our powder in it.
We’ll do a process where we vortex, we shake up the sample really good, we’ll boil it
so that any cells will break open and release their ATP; that’s the energy currency of
life.
That’s what we’re looking for with our assay here.
Once the cells have broken open in the boiling water, released all of their ATP, we’ll
spin the samples so that the sediment from our rock drops to the bottom, leaving only
the liquid with the ATP in it at the top.
We’ll take that, add another reagent.
It’s actually luciferase from fireflies!
And it basically has two different forms, one inert form, and it is able to be converted
to another form that glows.
And very conveniently it takes exactly one molecule of ATP to do that.
So if you put in a very precisely-measured amount of this protein, you will see that
it glows, which you can measure, and you can do some math and figure out how much it glowed
over what period of time and you can figure out very precisely how much ATP was in your
sample.
So, fireflies use that to light up their bums, we’re using it to find out how much ATP
is in the sample!
There’s three important things to know about ATP that makes it useful for understanding
what it means in context.
The first is, there’s no known way of making it without life.
In other words, if you find it on Earth, you can be pretty darn sure that something was
alive there that made it.
The second is, it’s universal.
Every form of life that we know of uses it, but the third thing you have to bear in mind
is: that’s very specific to Earth biochemistry.
Yes, it’s a very good biosignature on earth, but there’s a lot of debate about whether
or not it would be a useful thing to look for in other planetary environments.
Ultimately, the goal of this work is to inform Mars sample return.
Now, some of the techniques that we’re using here are very Earth-life specific, for example,
the ATP assay.
Now, if I were designing a Mars rover, I might use some other techniques that are more agnostic
to types of life that, perhaps, have evolved separately from life here on Earth.
However, it’s a really powerful tool.
By looking at the amount and the distribution of ATP in our sample sites, we can map that
to the amounts and distributions of life, and then we can use that to help figure out
what patterns we should be searching for with other life-detection instruments.
Ideally, we would like to be able to be a real Mars rover and do everything in the field
right there, but then there’s still some tests that we need instruments back home in
the states to do.
Now that we’re home, we want to get more of the physical parameters of the sample,
like the percent moisture content, the relative grain size distributions of the different
little particulates of the sample.
We also want to get more geochemical data, and with this we can do X-Ray Diffraction,
which gives us a better understanding of the connectivity and the elements at the same
time.
XRD stands for X-Ray Diffraction, and it shoots an x-ray beam at your powder sample, and based
on the angles and the intensities at which the x-ray beam diffracts, you can tell what
elements are in your sample.
And we can start to firm up the XRF data with laboratory confirmation of that, and we can
also do RAMAN spectroscopy, which is kind of the other side of the hand from the IR
reflectance spectroscopy.
We can also get more into the biological analyses.
And this would be similar to a Mars sample return type of depth of analysis.
These are the sorts of analyses that are very challenging to do with an in-situ mission.
There are a couple of analyses that we will do on these samples.
We will extract the DNAs and we will try and see how much DNA we can find in it, and we
will sequence them to basically look at sequences where we are able to identify what sort of
microbes are in there, and in what abundances.
One of the ways we get DNA from our samples is by mixing them with different solutions,
and then, these solutions will let us break open our cells to get to our DNA.
And then, once we have the DNA in our solution, we can put it in a machine that will spin
really fast and that will separate our DNA out so we can get to it.
Now that we have our DNA, because these samples come from an Icelandic lava field, there’s
not going to be much of it.
We have a technique that will let us act like a photocopier for DNA; we’re going to be
able to copy our DNA over and over and over, and get a bunch of it so that we can then
look at it with other instruments that aren’t as sensitive.
So now that we have a bunch of our DNA, we have another machine that will read it.
It will literally look through each part of the DNA and tell us what it is, and then,
we can relate that to microorganisms that live out in the world.
And we can figure out what exactly is in our sample.
So now that we know each one of our DNA strands corresponds to, and we have an idea of what’s
living in our samples, we can then do some fancy statistics to determine if each of our
samples has different things living in it.
And this will give us an idea if things are changing as we go from sample site to sample
site.
So, with the ATP that we got in the field, we know how active they were.
And with the DNA, we know how many there are, within reason.
And then we can also start to figure out who they are; who’s in the sample and how the
different communities that we’ve selected at different places, how they vary and may
interact with each other.
All of these scientists are working together across space to figure out what the data means
and everybody is an expert in their own area.
What we’re able to do is go in with each dataset and plot it against another dataset
and try to figure out what are the correlations; where do we get lines or groupings of different
types of measurements.
And that tells us that’s a good spot to look for life.
And we can start to get these correlations and groupings, which help inform future sample
selection, not just for FELDSPAR, but for other geochemical and planetary science studies.
For example, Mars 2020 and Mars sample return.
They’re planning on caching, collecting some samples, and then, ultimately, sending
them back here to Earth for analysis.
Now, we hope to collect the right number of samples because we can only collect a few,
and we’re hoping that we can help inform that decision.
Even on, you know, a few centimeter scale, or a meter scale, the types of life, the amount
of life you see are very different.
We’re trying to figure out how we can use other instruments, some of our field instruments
to say, “OK, you want to collect that one, not this one, because the chances of finding
life are better.”
That’s what we’re hoping to achieve, that we can use to help give Mars 2020 the tools
it needs to collect just the right samples.