Horizon (1964–…): Season 39, Episode 14 - Life on Mars - full transcript
In 2001 a new NASA probe was launched.
Called Odyssey,
it was sent to Mars to carry out the most detailed
analysis ever of the planet's surface.
What it has discovered
may be about to answer
one of the great questions
and solve one of astronomy's
biggest mysteries.
Are we alone in the Universe
or is there life on Mars?
Ever since people first looked up
into the night sky
there's been a question
that has bothered us all.
From the smallest children
to the world's greatest astronomers,
all have wondered -
are we alone in the Universe?
The question of life beyond
comes to me strongest at night,
looking up at the stars
and looking at all
those little points of light
and wondering is this galaxy
full of life
or is this it?
It's a question that society
has often been asking over the ages.
We really just want to know
how did we get here,
why do we exist,
are we the only people in the Universe,
are we the only signs of life?
This search for life elsewhere
in the Universe
is perhaps the greatest
scientific quest of all.
But so far most efforts
have concentrated on just one planet.
Searching for life
is a difficult job.
What we'd like to be able to do
is travel to all these distant
worlds and scoop up samples.
Unfortunately the worlds that we can travel
to are the other planets in our solar system
and none of them are very good
in terms of prospecting for biology.
The best one is probably Mars.
Mars, one of our nearest neighbours,
just 60 million kilometres away.
The reason Mars is important
is because it's close by.
It's our nearest neighbour
to Earth
and we'd like to see
if life is there
because if we can find life
in two places in our solar system,
we know that life isn't unique
here just on Earth,
and it's much more likely
that life will exist elsewhere,
perhaps elsewhere in our solar system,
perhaps in other solar systems,
other parts of the Universe.
I think it is exciting
because it would imply that
if life rose independently on Mars,
the implication is that life
is pervasive throughout the Universe.
This is why Mars has
so obsessed scientists.
If life has arisen independently
on the planet just next to us,
then the chances must be
that life could be everywhere.
In which case, we are not alone.
The idea of life on Mars
was first popularised by an American astronomer
called Percival Lowell, in the 1890s.
He claimed he could see evidence
of a civilisation on Mars.
The lines criss-crossing
its surface, he believed,
were not geological accidents
but canals linking Martian cities.
Lowell's vision inspired
a global obsession with aliens
and spawned thousands of movies
about little green men.
But in July 1965 reality intruded.
Mariner 4 became the first probe
to fly by Mars and photograph it.
At last the world would see what the land
of the little green men really looked like.
When Mariner 4 flew by Mars
it just took a few pictures
with a very course grain television camera,
and what it showed was a surface
that could have been the moon.
Clearly there was
no civilisations, no canals,
probably not even trees and insects.
It was really a bleak landscape
that was being photographed there,
it really gave the impression
that Mars was dead and always
been dead since its early history,
and that really dashed the hopes of dreamers
thinking that maybe there was life there.
Conditions on Mars were so harsh
that it was hard to imagine
any life surviving there.
The idea of sophisticated
aliens was wiped out.
We know that conditions on Mars
today are not very good for life.
If you were to go out
on Mars without a space suit,
and I don't recommend it,
but if you were,
what would happen is your body fluids
would literally start to boil,
because the vapour pressure
on Mars is lower
than the boiling point
of water at body temperature.
So this would not be a very good thing
in terms of your ears, eyes and nose and throat.
You would quickly suffocate and essentially
drown in your own bodily fluid.
It was clear that Mars could not
be home to advanced life forms.
For a while it meant that perhaps
we were alone after all.
Mars, it seemed, was a dead end.
It wasn't until the years later
during expeditions in the 70s
that they saw that the image of Mars
as a dead planet was not quite right.
After a while when people
started thinking about it though,
when you looked more into it,
then you started realising...
well... yeah, it is desolate,
it's very dry,
but you know there are
other things going on.
Volcanoes and explosions had clearly
once torn across this planet,
leaving the surface
pockmarked and scarred.
Far from being dead,
Mars had all the features
of once being very much alive.
We started seeing all these incredible things
It has mountains there bigger
than any mountains on Earth.
It's got canyons that are
bigger than the Grand Canyon.
All these volcanoes, parts of Mars
was crated, parts weren't.
It's got tremendous altitude variations
over the surface of the planet.
It's just a very rich environment.
So that was a very exciting time.
We were surprised by almost everything.
It wasn't just the geology
of Mars that was surprising.
It also contained all the basic
ingredients for life.
Here was a planet that had
all the elements needed for life:
carbon, oxygen, nitrogen, sunlight,
and yet there was
no clear evidence of life.
To me this is mystery story.
It was a sort of - lights on
but nobody's home - result.
So life could form on Mars.
There's nothing there preventing it.
We do have
the basic building blocks.
These discoveries raised the stakes.
Here was a planet
similar to our own.
Mars might not have
cities or civilisations
but it could be home
to other smaller life forms
like microbes.
Chris McKay is NASA's
leading microbe expert.
He believes that finding even these minute
organisms would be of the utmost importance.
If we find life on Mars, we're almost
certainly going to find are microbes,
little tiny microscopic organisms.
You think well
what's the big deal?
Well in fact for most
of Earth's history,
all the life was
on Earth was microbes.
And so going to Mars and even finding
the smallest, dumbest, littlest bug
will still be important
because it'll tell us
that here in our own
back yard life started twice.
And so the hard part is possible.
The evolution into intelligence
and humanlike beings
is pretty straightforward compared
to the question of could it get started.
And there's something about microbes
that makes them well suited
to surviving on Mars -
they're incredibly tough.
They're the organisms also
that live in the extremes.
They can live in the very high temperature
and very high acid and very high salt.
They define the limits of life
and the potential of life.
But hunting for microbes
would not be easy.
Mars is 6,700 kilometres wide
and it has the same
land mass as Earth.
Microbes, on the other hand, are tiny.
You could fit nearly 10 million
on just your fingertip.
It would be far harder
than finding a needle in a haystack.
Scientists had
to narrow down their search.
So they looked for the one thing
that had to be present for life to form -
a place where you could
find microbes.
The search for life
is the search for liquid water.
Life on Earth
is basically full of water.
Life forms are basically little bags
of water with little.. a few other ingredients added.
But water is the main component.
Water is what makes it work.
On Earth all life is based on water.
It's the main constituent of every cell.
Because water is basically inert,
it's the perfect medium
for different types of molecule
to flow around, meet
and react together.
It enables life to form.
William Boynton is Professor of Planetary
Sciences at the University of Arizona,
and he's dedicated his life
to looking for water on Mars.
The link between life
and water is very strong.
Even here in the desert there's life all around us.
Now in looking
for life on Mars,
we use our basis
of knowledge on Earth,
and on Earth we know
life requires water.
So on Mars we're going to be looking
for the places where we can find water.
Just like the desert,
Mars may look dry,
but there are signs of water there.
It's been known for almost a century
that there are ice caps
at the Martian poles.
When we look up at Mars
we see a dry, dusty planet.
It doesn't look
like a place for life.
But there's tiny amounts
of water in the atmosphere
and we know there are
ice concentrations in the poles.
So we're actually very optimistic
that because there is at least
a speck of water on Mars,
there might be a speck of life.
However, while the Poles
contain water ice,
temperatures there can reach
a staggering minus 150 degrees centigrade
which meant these were not
good places to search for life.
The conditions there
are way too extreme.
It's really just too cold
and we really need liquid water for life.
What we want to find on Mars
is some place where we can find
water in the more temperate regions.
What we ultimately need
to find is liquid water.
But the first indications were
that if life needed liquid water,
then Mars was out of luck.
Conditions all over
the planet seemed too cold.
There appeared to be
no prospect of water anywhere...
These photographs changed everything.
Taken by the Viking
Space Probe in 1976
they showed what looked
like dried up river valleys.
You can see one here.
You can see there's a valley through here
and you can see it branches,
there are tributaries,
here's one branch going
off here with tributaries.
So this looks very much
like a terrestrial river system.
If these were
dried up river beds
it meant that Mars must once
have had the perfect conditions for life.
For Mars to have rivers,
it must once have had streams,
rain, clouds and an atmosphere,
a planet just like the Earth today -
if these were rivers.
They had to be sure.
The answers would come in 1998
with the launch
of Mars Global Surveyor.
It was equipped with the latest
high resolution electronic cameras.
Sections of the valleys were
revealed in fantastic detail.
Some valleys had been eroded
and filled in with sand.
It was impossible to say
how they'd been formed.
They could have been carved
by water, or soil, or carbon dioxide.
Then, after they'd searched
through thousands of images,
they found this -
a winding valley 2 km wide.
And at a bend in the canyon,
a tiny channel.
The unmistakable trace
of an ancient river.
This is the best evidence
that we have
that climate in the past
was different from what it is today.
Only a river would leave
a meandering trace like this:
only a river would leave the traces
of silt they saw in the bend,
and only water could carve
the winding channel feeding into it.
But they soon found more
than just a few rivers.
They discovered evidence that water had
once existed on Mars in colossal quantities.
The evidence came from another
probe that reached Mars in 1997.
It landed in an enormous channel
and sent back images of huge boulders
scattered around the Martian surface.
Scientists were puzzled.
What could this strange
pattern signify?
One man, looking on, knew exactly
what those scattered stones meant - Jim Rice.
Rice had seen the same
thing in Iceland,
one of the few places
on Earth with similarities to Mars.
It too is extremely cold,
and most of the water
is frozen into glaciers.
And also like Mars, buried underground,
are massive volcanoes.
This powerful combination
has shaped the entire landscape.
When a volcano erupts,
lakes of steaming melt water
form high up on top of the glacier
until the enormous weight
of water forces its way down,
bursting out from
the base of the glacier.
These are the biggest
floods on Earth,
a surging wall of water
stretching for kilometres.
In their wake they leave vast
planes littered with boulders.
To a geologist these boulder
fields contain unmistakable evidence
of the flood waters
that ripped through here.
Okay, well this is really
a classic textbook example,
these two large boulders here.
The size of them indicates this was an enormous
flood that deposited these features,
but also if you look
at their geometry,
these boulders are kind
of dipping back in this direction.
This has given us information about the path
that floodwaters took that deposited these boulders.
The floodwaters were going in this
direction when these rocks were deposited.
Now there's other interesting
things in the scene here.
For instance, notice some of these
smaller rocks are very well rounded,
and these little nicked corners
of these boulders here,
these are kind of percussion marks
and these are produced in a water...,
highly turbulent water column
when the boulders and rocks are
basically slamming into one another,
knocking the corners off.
These things all grouped together
just tell you there's no doubt
this was a catastrophic flood deposit.
The pictures from Mars showed the rocks
in exactly the same pattern as on Iceland.
Here were the slanting boulders
lined up by the floodwaters,
and the cameras on the rover provided
detailed views of the individual rocks
with their telltale chipped edges.
It seemed that the vast Martian channels
had been carved by enormous floods.
It was final confirmation
that Mars had once been
warm and wet like the Earth,
and that meant that there really was
every chance for life to have evolved there.
But even if there had been water,
life doesn't start overnight.
Even a simple microbe is
the product of complex chemical systems
that take millions
of years to evolve.
Had the water lasted
long enough for life to form?
Well, when we look
at the history of life on Earth,
it appears to start very quickly,
maybe a hundred million years.
Now that seems like a long time
but for a planet that's short.
So I would guess that
if there was water on Mars
for a couple
of hundred million years,
then life had a good shot
at getting started there.
And soon they found evidence that water
had been there for millions of years.
It was all because of
one very important picture.
Sent back in December 2000,
it was a vast formations
of sedimentary rock.
Sediment is basically
made of sand
and can only have been
deposited over millions of years
by a huge body of water
like a lake or an ocean.
It showed that there had not
only been masses of water,
but that it had been around
easily long enough for life to form.
The sediments on the surface
are now dry and exposed.
If they ever had contained life,
it cannot possibly have survived.
However, scientists hope that microbes
deeper down might still be alive,
frozen in the ground.
To find the actual organic
remains of a Martian organism,
we're going to need
to go to frozen material.
In the ice life might have been preserved
frozen in a state of suspended animation.
No one at this stage can know if microbes,
formed millions of years ago,
could have survived on Mars.
But there are indications
that this really is possible.
Antarctica -
the closest place on Earth
to conditions on Mars.
More extreme even than Iceland -
it's the coldest place
on our planet.
Until a few years ago,
no one thought that anything could survive
being deep frozen for millions of years.
But research here
has helped change that.
The ground here is permafrost,
a mixture of soil
and ice frozen together.
A group of Russian scientists
have teamed up with NASA
to drill down into it
in search of micro organisms.
It's work that's been
done in Russia for years.
The people found the micro-organisms
in the permafrost in the end of 19th century.
It was done especially
in Russia when people found mammoths.
Back then it was the mammoths
they were after.
But David Gilichinsky's team
have now drilled so deep
that they've reached permafrost
that was laid down millions of years ago.
The frozen cores were taken back
to their laboratory.
Samples were taken
from the centre of the core,
then they looked
for signs of life.
They discovered that bacteria
can survive in the permafrost
for far longer than anyone
had thought possible.
In 2001 they found bacteria
which may turn out
to have been at -20°C
for more than 10 million years.
We have some data
but we are not sure 100%.
But probably now we have isolated
bacteria from Antarctic permafrost
it's between 8
and 15 million years old.
Bacteria have been buried
alive here in frozen ground
since before the beginning
of human evolution.
If life can survive
in Antarctica for 15 million years,
then something could be waiting
to be revived on Mars.
These discoveries put new urgency
in the quest to find water on Mars.
There was now a real possibility
that they might find something alive.
So authorisation came
from the very top:
send more missions to Mars.
NASA launched several probes
with the express purpose
of mapping the composition
of the Martian surface.
But they never got there.
The first disappeared
into deep space.
Another missed its target
when its co-ordinates were confused.
One NASA control centre was working in metric,
the other in feet and inches.
They never lined up and the probe exploded
in the Martian atmosphere.
William Boynton had lost
precious equipment on both missions.
But he decided
to try one more time.
This was really my third attempt
to get to Mars,
and some of my colleagues
were saying:
"Bill, are you crazy?
You're doing this a third time?
Why are you putting
so much time in on this?"
And I just couldn't say no.
I think there was just a calling
that I had to go back.
So once again he set about designing
an instrument to detect underground water on Mars.
After the previous failures
the pressure was on.
The role my instrument has taken
in this search for water on Mars
is we have a device called
a gamma ray spectrometer
and it's designed to determine what elements
are present on Mars that make up the surface,
and probably the most
important one of those
is hydrogen 'cause that's
the main constituent element in water.
We have ignition and lift off
of a Delta 2 rocket carrying
NASA on an Odyssey back to Mars.
On the 7th April, 2001,
NASA launched Odyssey
carrying Boynton's device,
and this time everything
went according to plan.
It's really hard to describe
exactly what it's like
to have an instrument
that you've built
be perched on top of a rocket
and actually get launched off into space,
and you think
I'm on my way to Mars.
Once in Mars' orbit
the instrument was deployed,
and the gamma ray detector
could get to work.
All elements, when they're struck by cosmic rays
from the sun and other stars, release gamma rays.
The wavelength of the gamma rays
differs from element to element,
so each has its own
signature wavelength.
One of these wavelengths
corresponds to hydrogen,
another wavelength would be iron,
another wavelength would be oxygen.
And so you go to that part
of the spectrum you're interested in
and you see you've got
a big peak there.
As Odyssey circled Mars
it started to pick up gamma rays.
The strength of the signal indicated
how much of any element it had found.
We were hopeful that we would see spots
where water had been concentrated.
We weren't sure
we would see that.
But it's these kind
of things that we're expecting to see
and actually very hopeful
that we would see.
The data was radioed back
from Odyssey to NASA
to the University of Tucson
and finally to Boynton's desk.
Building up the picture
takes a long time
because any given spectrum that comes back
is only 20 seconds worth of data.
We get a new spectrum
every 20 seconds,
so we actually slowly build up
an image in our database.
As the data came through,
a picture started to build.
When I first saw the signal,
I was looking through it and at first
trying to find the hydrogen signal.
And then when I saw it,
it was so big, I couldn't believe it.
I actually had
to do some checks
to see could this be real
or somehow did we mess things up.
It could only mean one thing.
There is water ice on Mars today,
and three is masses of it.
Boynton and his team have discovered
a vast area of ice in the southern hemisphere.
A froze ocean over 5000km wide.
There's plenty of water there.
What we found is just in the surface.
If we melted that, it would be enough
to fill Lake Michigan two times over.
There actually is probably a lot more
because we don't know how deep the ice goes,
that's just in the upper metre
there's that much.
It could be 10 metres deep,
it could be 100 metres deep.
There's a lot of ice there.
The ice they have found
is trapped in the ground,
a permafrost just like in Antarctica.
Crucially it's located at latitudes on Mars
where conditions are relatively mild,
where there's a real chance
of life surviving.
One of the most interesting things about this
is its not right up near the South Pole
or right not near the North Pole.
It actually goes down
to temperate latitudes.
It goes all the way down
to about 45° latitude.
This is like the equivalent
of Paris France on Earth.
This is really a place where it's much
more likely we can find life I feel.
But there was something even better.
Odyssey may not just
have found ice.
There may also be liquid water -
and that means there could be
living creatures there too.
Right now there might be
liquid water on Mars.
It's not going to be on the surface
but if we go down deep enough,
it's almost certain we will find
liquid water at some point beneath the ice.
It's all down to the interior
of the planet.
Scientists believe that Mars' heart may be
a great core of molten rock and metal.
At the very centre it could reach
temperatures of almost 2000°C.
This heat is spread outwards,
so that despite
the very cold surface of Mars,
just tens of metres down,
it may be warm enough to melt ice.
What Odyssey is seeing really may be
just the tip of the iceberg.
There could be, underneath that layer
of ice that it could detect,
a literal frozen ocean
of water beneath that.
Surprisingly there could be life today
on Mars beneath the ice in the liquid water.
So the Odyssey results
are also telling us
that we ought to reconsider
the possibility of life on Mars today,
search for it more vigorously
than we might have.
Odyssey's discoveries mean that there is now
a genuine possibility that there is life on Mars.
And if so, then we will soon have
to start reconsidering our place in the Universe.
Odyssey's discoveries
are so sensational
that scientists are beginning
to speculate
what strange creatures
might be there waiting for us.
What might an alien look like?
Would they, for instance, be based
on the same biological principles as we are?
When we look at life on Earth
we see that all life on Earth
uses the same chemistry
and the same genetic code,
the same hardware,
the same software.
It's really interesting to wonder
if life on Mars, if it started independently,
would it use the same code,
the same chemicals?
On Earth everything
is based on DNA,
but could it be that life on Mars
is completely different,
that there is an utterly
alien way of doing genetics.
Life on Earth is basically proteins and DNA,
so we can wonder if there's life on Mars
will it also be DNA and proteins,
the same type of DNA,
the same type of proteins.
One might think that DNA is
such a complex arrangement of molecules
that it's unlikely to have
the same set on another planet.
Equally, we may find
that DNA is also on Mars.
It may be that our way
is the only way of life.
On the other hand, we might argue
that DNA is optimal way to do it and that life
is going to discover this best possible solution
no matter where it starts.
So we're not sure
if life will be different or the same.
My guess is that
it'll be different,
and if life started
separately on Mars,
it will have a different genetic structure
than life on Earth.
But there will only be one way
to find this out conclusively.
To examine life in this detail,
someone will have to get up close.
We really have
to go find the facts,
and the facts are on Mars
and we've got to go find them.
We can hypothesise all we want,
but until we actually find the facts
on the ground, we won't know for sure.
It means that someone
will have to go to Mars,
and it just so happens that there is
an organisation already preparing to go…
Bo Maxwell is the UK President
of the Mars Society,
a group dedicated to colonising
our neighbouring planet.
Humans, by their very nature,
are explorers.
In our time we've travelled
from the African Rift Valley,
climbed mountains, crossed oceans and settled
just about everywhere there is to settle on Earth.
We've built our houses,
our towns, our cities,
and now the time has come
to move beyond the Earth
and Mars offers us the very best opportunity
to go to another world and settle somewhere else.
The Mars Society have their very own
low cost plan to get to Mars.
Bo is one of the masterminds.
He's working on it
from his home in Milton Keynes.
The aim of the Mars Society
is definitely to go to Mars.
We want to go there,
we want to explore and colonise.
The advantage of sending humans to Mars
is our greater ability to explore.
We are much more efficient
than robots.
Human beings have a tremendous
advantage over robot vehicles.
We have our own intuition,
our own intelligence
which leaves our robot vehicles standing.
A human being on Mars
can stand on the surface,
he can look around,
she can look around,
and instantly spot areas where life
may well be possible and life may exist.
The discovery of water ice on Mars
has reinvigorated their plans.
Water is the one thing
any colonisers would need.
Well hearing that Odyssey had found
subsurface water on Mars
was enormously exciting for somebody
who is involved in planning to send humans to Mars.
Water has a number
of important uses for us.
At the most basic, it provides
drinking water once it's been purified,
and it provides water
for hygiene purposes as well.
More important than that,
we can electrolyse it.
We can actually split it
into hydrogen and oxygen.
Oxygen obviously we can use
for breathing
and we can also use it as a fuel stock with
the hydrogen for our vehicle to come back home,
and we can also use the hydrogen itself
in fuel cells to power our rover vehicles.
So the ability to use water that exists on Mars
is tremendously important to human missions on Mars.
But any colonising of Mars
would require extreme action.
Some believe it would need
what scientists call 'terraforming',
transforming the entire planet
into an artificial Earth.
This involves growing plants
to create more oxygen, and an atmosphere.
It requires raising
the temperature of the planet,
raising the atmospheric density through melting
the icecaps and freeing up the carbon dioxide.
But the key thing about the water ice
on Mars is once we've done that,
then we can let that water exist free
form on the surface of the planet,
and it again will create
rivers, lakes, oceans,
which we can use
and the plants can use to survive.
But plants grown on Mars
may be very different from those on Earth.
The lower gravity on Mars,
one third of that on Earth,
means that both plants and animals
might grow taller and thinner.
I think we're all familiar with seeing
the giant redwood trees of California.
They're somewhat unusual
here on Earth.
They only occur
in a few localised places.
On Mars it will be the norm.
You would see these tremendously
tall, slim trees,
possibly with very high canopies
on them as well.
Animal life could be affected
the same way as well.
We could see new breeds
of animal that we haven't seen before,
very tall, thin sheep
living on Mars.
But again early days,
very much speculative.
This lower gravity would also have
implications for any people born there.
If humans live on Mars
for many generations,
they might develop into different forms
than humans on Earth.
They might be taller,
they might be thinner,
they might have
weaker muscles and weaker bones.
It might even be possible that they would not be able
to function very effectively on the gravity of Earth.
In that case, Mars' society
and Earth's society might split
and become effectively
two different species.
Of course, any terraforming
is still a long way off.
The next few expeditions to Mars
will definitely be made by machines.
NASA are sending two rovers capable of travelling
over 100 metres a day in search of signs of water,
while the Europeans
are sending the Beagle 2 probe.
Odyssey will continue to orbit Mars
to find out the extent of the ice.
Is it just in the southern hemisphere
or all over the planet?
Now we're starting to explore
what's going on in the north
and we're seeing
a very similar signal there,
but it's very likely we're going to find at least
as much ice in the north as we saw in the south,
and perhaps even more.
They also want to find out
how deep the water goes,
and whether there really are underground
lakes present as people now suspect.
The mounting evidence for water on Mars
means it's looking more and more habitable.
We may he approaching
an answer to the great question
of whether there's other life
out there in the Universe.
My guess is that if you have
the right ingredients life is inevitable,
but it's just a guess.
We have just one example
here on Earth.
We don't know for sure
if that's the case,
and that's why I want
to go to Mars, to test that guess,
to turn it from a guess
to a scientific fact.
My feeling is that it's likely
that there's life elsewhere in the Universe.
There are just so many other stars,
so many other planets.
It's hard for me to imagine that this is the only
life forms we have is what we have here on Earth.
100 years ago
some astronomers believed
that there were civilisations
on Mars with cities and canals.
They were wrong about the cities,
but the water is there,
so maybe the life is too,
after all.
But ultimately we may have
to go there to answer the question -
are we alone in the Universe?
Called Odyssey,
it was sent to Mars to carry out the most detailed
analysis ever of the planet's surface.
What it has discovered
may be about to answer
one of the great questions
and solve one of astronomy's
biggest mysteries.
Are we alone in the Universe
or is there life on Mars?
Ever since people first looked up
into the night sky
there's been a question
that has bothered us all.
From the smallest children
to the world's greatest astronomers,
all have wondered -
are we alone in the Universe?
The question of life beyond
comes to me strongest at night,
looking up at the stars
and looking at all
those little points of light
and wondering is this galaxy
full of life
or is this it?
It's a question that society
has often been asking over the ages.
We really just want to know
how did we get here,
why do we exist,
are we the only people in the Universe,
are we the only signs of life?
This search for life elsewhere
in the Universe
is perhaps the greatest
scientific quest of all.
But so far most efforts
have concentrated on just one planet.
Searching for life
is a difficult job.
What we'd like to be able to do
is travel to all these distant
worlds and scoop up samples.
Unfortunately the worlds that we can travel
to are the other planets in our solar system
and none of them are very good
in terms of prospecting for biology.
The best one is probably Mars.
Mars, one of our nearest neighbours,
just 60 million kilometres away.
The reason Mars is important
is because it's close by.
It's our nearest neighbour
to Earth
and we'd like to see
if life is there
because if we can find life
in two places in our solar system,
we know that life isn't unique
here just on Earth,
and it's much more likely
that life will exist elsewhere,
perhaps elsewhere in our solar system,
perhaps in other solar systems,
other parts of the Universe.
I think it is exciting
because it would imply that
if life rose independently on Mars,
the implication is that life
is pervasive throughout the Universe.
This is why Mars has
so obsessed scientists.
If life has arisen independently
on the planet just next to us,
then the chances must be
that life could be everywhere.
In which case, we are not alone.
The idea of life on Mars
was first popularised by an American astronomer
called Percival Lowell, in the 1890s.
He claimed he could see evidence
of a civilisation on Mars.
The lines criss-crossing
its surface, he believed,
were not geological accidents
but canals linking Martian cities.
Lowell's vision inspired
a global obsession with aliens
and spawned thousands of movies
about little green men.
But in July 1965 reality intruded.
Mariner 4 became the first probe
to fly by Mars and photograph it.
At last the world would see what the land
of the little green men really looked like.
When Mariner 4 flew by Mars
it just took a few pictures
with a very course grain television camera,
and what it showed was a surface
that could have been the moon.
Clearly there was
no civilisations, no canals,
probably not even trees and insects.
It was really a bleak landscape
that was being photographed there,
it really gave the impression
that Mars was dead and always
been dead since its early history,
and that really dashed the hopes of dreamers
thinking that maybe there was life there.
Conditions on Mars were so harsh
that it was hard to imagine
any life surviving there.
The idea of sophisticated
aliens was wiped out.
We know that conditions on Mars
today are not very good for life.
If you were to go out
on Mars without a space suit,
and I don't recommend it,
but if you were,
what would happen is your body fluids
would literally start to boil,
because the vapour pressure
on Mars is lower
than the boiling point
of water at body temperature.
So this would not be a very good thing
in terms of your ears, eyes and nose and throat.
You would quickly suffocate and essentially
drown in your own bodily fluid.
It was clear that Mars could not
be home to advanced life forms.
For a while it meant that perhaps
we were alone after all.
Mars, it seemed, was a dead end.
It wasn't until the years later
during expeditions in the 70s
that they saw that the image of Mars
as a dead planet was not quite right.
After a while when people
started thinking about it though,
when you looked more into it,
then you started realising...
well... yeah, it is desolate,
it's very dry,
but you know there are
other things going on.
Volcanoes and explosions had clearly
once torn across this planet,
leaving the surface
pockmarked and scarred.
Far from being dead,
Mars had all the features
of once being very much alive.
We started seeing all these incredible things
It has mountains there bigger
than any mountains on Earth.
It's got canyons that are
bigger than the Grand Canyon.
All these volcanoes, parts of Mars
was crated, parts weren't.
It's got tremendous altitude variations
over the surface of the planet.
It's just a very rich environment.
So that was a very exciting time.
We were surprised by almost everything.
It wasn't just the geology
of Mars that was surprising.
It also contained all the basic
ingredients for life.
Here was a planet that had
all the elements needed for life:
carbon, oxygen, nitrogen, sunlight,
and yet there was
no clear evidence of life.
To me this is mystery story.
It was a sort of - lights on
but nobody's home - result.
So life could form on Mars.
There's nothing there preventing it.
We do have
the basic building blocks.
These discoveries raised the stakes.
Here was a planet
similar to our own.
Mars might not have
cities or civilisations
but it could be home
to other smaller life forms
like microbes.
Chris McKay is NASA's
leading microbe expert.
He believes that finding even these minute
organisms would be of the utmost importance.
If we find life on Mars, we're almost
certainly going to find are microbes,
little tiny microscopic organisms.
You think well
what's the big deal?
Well in fact for most
of Earth's history,
all the life was
on Earth was microbes.
And so going to Mars and even finding
the smallest, dumbest, littlest bug
will still be important
because it'll tell us
that here in our own
back yard life started twice.
And so the hard part is possible.
The evolution into intelligence
and humanlike beings
is pretty straightforward compared
to the question of could it get started.
And there's something about microbes
that makes them well suited
to surviving on Mars -
they're incredibly tough.
They're the organisms also
that live in the extremes.
They can live in the very high temperature
and very high acid and very high salt.
They define the limits of life
and the potential of life.
But hunting for microbes
would not be easy.
Mars is 6,700 kilometres wide
and it has the same
land mass as Earth.
Microbes, on the other hand, are tiny.
You could fit nearly 10 million
on just your fingertip.
It would be far harder
than finding a needle in a haystack.
Scientists had
to narrow down their search.
So they looked for the one thing
that had to be present for life to form -
a place where you could
find microbes.
The search for life
is the search for liquid water.
Life on Earth
is basically full of water.
Life forms are basically little bags
of water with little.. a few other ingredients added.
But water is the main component.
Water is what makes it work.
On Earth all life is based on water.
It's the main constituent of every cell.
Because water is basically inert,
it's the perfect medium
for different types of molecule
to flow around, meet
and react together.
It enables life to form.
William Boynton is Professor of Planetary
Sciences at the University of Arizona,
and he's dedicated his life
to looking for water on Mars.
The link between life
and water is very strong.
Even here in the desert there's life all around us.
Now in looking
for life on Mars,
we use our basis
of knowledge on Earth,
and on Earth we know
life requires water.
So on Mars we're going to be looking
for the places where we can find water.
Just like the desert,
Mars may look dry,
but there are signs of water there.
It's been known for almost a century
that there are ice caps
at the Martian poles.
When we look up at Mars
we see a dry, dusty planet.
It doesn't look
like a place for life.
But there's tiny amounts
of water in the atmosphere
and we know there are
ice concentrations in the poles.
So we're actually very optimistic
that because there is at least
a speck of water on Mars,
there might be a speck of life.
However, while the Poles
contain water ice,
temperatures there can reach
a staggering minus 150 degrees centigrade
which meant these were not
good places to search for life.
The conditions there
are way too extreme.
It's really just too cold
and we really need liquid water for life.
What we want to find on Mars
is some place where we can find
water in the more temperate regions.
What we ultimately need
to find is liquid water.
But the first indications were
that if life needed liquid water,
then Mars was out of luck.
Conditions all over
the planet seemed too cold.
There appeared to be
no prospect of water anywhere...
These photographs changed everything.
Taken by the Viking
Space Probe in 1976
they showed what looked
like dried up river valleys.
You can see one here.
You can see there's a valley through here
and you can see it branches,
there are tributaries,
here's one branch going
off here with tributaries.
So this looks very much
like a terrestrial river system.
If these were
dried up river beds
it meant that Mars must once
have had the perfect conditions for life.
For Mars to have rivers,
it must once have had streams,
rain, clouds and an atmosphere,
a planet just like the Earth today -
if these were rivers.
They had to be sure.
The answers would come in 1998
with the launch
of Mars Global Surveyor.
It was equipped with the latest
high resolution electronic cameras.
Sections of the valleys were
revealed in fantastic detail.
Some valleys had been eroded
and filled in with sand.
It was impossible to say
how they'd been formed.
They could have been carved
by water, or soil, or carbon dioxide.
Then, after they'd searched
through thousands of images,
they found this -
a winding valley 2 km wide.
And at a bend in the canyon,
a tiny channel.
The unmistakable trace
of an ancient river.
This is the best evidence
that we have
that climate in the past
was different from what it is today.
Only a river would leave
a meandering trace like this:
only a river would leave the traces
of silt they saw in the bend,
and only water could carve
the winding channel feeding into it.
But they soon found more
than just a few rivers.
They discovered evidence that water had
once existed on Mars in colossal quantities.
The evidence came from another
probe that reached Mars in 1997.
It landed in an enormous channel
and sent back images of huge boulders
scattered around the Martian surface.
Scientists were puzzled.
What could this strange
pattern signify?
One man, looking on, knew exactly
what those scattered stones meant - Jim Rice.
Rice had seen the same
thing in Iceland,
one of the few places
on Earth with similarities to Mars.
It too is extremely cold,
and most of the water
is frozen into glaciers.
And also like Mars, buried underground,
are massive volcanoes.
This powerful combination
has shaped the entire landscape.
When a volcano erupts,
lakes of steaming melt water
form high up on top of the glacier
until the enormous weight
of water forces its way down,
bursting out from
the base of the glacier.
These are the biggest
floods on Earth,
a surging wall of water
stretching for kilometres.
In their wake they leave vast
planes littered with boulders.
To a geologist these boulder
fields contain unmistakable evidence
of the flood waters
that ripped through here.
Okay, well this is really
a classic textbook example,
these two large boulders here.
The size of them indicates this was an enormous
flood that deposited these features,
but also if you look
at their geometry,
these boulders are kind
of dipping back in this direction.
This has given us information about the path
that floodwaters took that deposited these boulders.
The floodwaters were going in this
direction when these rocks were deposited.
Now there's other interesting
things in the scene here.
For instance, notice some of these
smaller rocks are very well rounded,
and these little nicked corners
of these boulders here,
these are kind of percussion marks
and these are produced in a water...,
highly turbulent water column
when the boulders and rocks are
basically slamming into one another,
knocking the corners off.
These things all grouped together
just tell you there's no doubt
this was a catastrophic flood deposit.
The pictures from Mars showed the rocks
in exactly the same pattern as on Iceland.
Here were the slanting boulders
lined up by the floodwaters,
and the cameras on the rover provided
detailed views of the individual rocks
with their telltale chipped edges.
It seemed that the vast Martian channels
had been carved by enormous floods.
It was final confirmation
that Mars had once been
warm and wet like the Earth,
and that meant that there really was
every chance for life to have evolved there.
But even if there had been water,
life doesn't start overnight.
Even a simple microbe is
the product of complex chemical systems
that take millions
of years to evolve.
Had the water lasted
long enough for life to form?
Well, when we look
at the history of life on Earth,
it appears to start very quickly,
maybe a hundred million years.
Now that seems like a long time
but for a planet that's short.
So I would guess that
if there was water on Mars
for a couple
of hundred million years,
then life had a good shot
at getting started there.
And soon they found evidence that water
had been there for millions of years.
It was all because of
one very important picture.
Sent back in December 2000,
it was a vast formations
of sedimentary rock.
Sediment is basically
made of sand
and can only have been
deposited over millions of years
by a huge body of water
like a lake or an ocean.
It showed that there had not
only been masses of water,
but that it had been around
easily long enough for life to form.
The sediments on the surface
are now dry and exposed.
If they ever had contained life,
it cannot possibly have survived.
However, scientists hope that microbes
deeper down might still be alive,
frozen in the ground.
To find the actual organic
remains of a Martian organism,
we're going to need
to go to frozen material.
In the ice life might have been preserved
frozen in a state of suspended animation.
No one at this stage can know if microbes,
formed millions of years ago,
could have survived on Mars.
But there are indications
that this really is possible.
Antarctica -
the closest place on Earth
to conditions on Mars.
More extreme even than Iceland -
it's the coldest place
on our planet.
Until a few years ago,
no one thought that anything could survive
being deep frozen for millions of years.
But research here
has helped change that.
The ground here is permafrost,
a mixture of soil
and ice frozen together.
A group of Russian scientists
have teamed up with NASA
to drill down into it
in search of micro organisms.
It's work that's been
done in Russia for years.
The people found the micro-organisms
in the permafrost in the end of 19th century.
It was done especially
in Russia when people found mammoths.
Back then it was the mammoths
they were after.
But David Gilichinsky's team
have now drilled so deep
that they've reached permafrost
that was laid down millions of years ago.
The frozen cores were taken back
to their laboratory.
Samples were taken
from the centre of the core,
then they looked
for signs of life.
They discovered that bacteria
can survive in the permafrost
for far longer than anyone
had thought possible.
In 2001 they found bacteria
which may turn out
to have been at -20°C
for more than 10 million years.
We have some data
but we are not sure 100%.
But probably now we have isolated
bacteria from Antarctic permafrost
it's between 8
and 15 million years old.
Bacteria have been buried
alive here in frozen ground
since before the beginning
of human evolution.
If life can survive
in Antarctica for 15 million years,
then something could be waiting
to be revived on Mars.
These discoveries put new urgency
in the quest to find water on Mars.
There was now a real possibility
that they might find something alive.
So authorisation came
from the very top:
send more missions to Mars.
NASA launched several probes
with the express purpose
of mapping the composition
of the Martian surface.
But they never got there.
The first disappeared
into deep space.
Another missed its target
when its co-ordinates were confused.
One NASA control centre was working in metric,
the other in feet and inches.
They never lined up and the probe exploded
in the Martian atmosphere.
William Boynton had lost
precious equipment on both missions.
But he decided
to try one more time.
This was really my third attempt
to get to Mars,
and some of my colleagues
were saying:
"Bill, are you crazy?
You're doing this a third time?
Why are you putting
so much time in on this?"
And I just couldn't say no.
I think there was just a calling
that I had to go back.
So once again he set about designing
an instrument to detect underground water on Mars.
After the previous failures
the pressure was on.
The role my instrument has taken
in this search for water on Mars
is we have a device called
a gamma ray spectrometer
and it's designed to determine what elements
are present on Mars that make up the surface,
and probably the most
important one of those
is hydrogen 'cause that's
the main constituent element in water.
We have ignition and lift off
of a Delta 2 rocket carrying
NASA on an Odyssey back to Mars.
On the 7th April, 2001,
NASA launched Odyssey
carrying Boynton's device,
and this time everything
went according to plan.
It's really hard to describe
exactly what it's like
to have an instrument
that you've built
be perched on top of a rocket
and actually get launched off into space,
and you think
I'm on my way to Mars.
Once in Mars' orbit
the instrument was deployed,
and the gamma ray detector
could get to work.
All elements, when they're struck by cosmic rays
from the sun and other stars, release gamma rays.
The wavelength of the gamma rays
differs from element to element,
so each has its own
signature wavelength.
One of these wavelengths
corresponds to hydrogen,
another wavelength would be iron,
another wavelength would be oxygen.
And so you go to that part
of the spectrum you're interested in
and you see you've got
a big peak there.
As Odyssey circled Mars
it started to pick up gamma rays.
The strength of the signal indicated
how much of any element it had found.
We were hopeful that we would see spots
where water had been concentrated.
We weren't sure
we would see that.
But it's these kind
of things that we're expecting to see
and actually very hopeful
that we would see.
The data was radioed back
from Odyssey to NASA
to the University of Tucson
and finally to Boynton's desk.
Building up the picture
takes a long time
because any given spectrum that comes back
is only 20 seconds worth of data.
We get a new spectrum
every 20 seconds,
so we actually slowly build up
an image in our database.
As the data came through,
a picture started to build.
When I first saw the signal,
I was looking through it and at first
trying to find the hydrogen signal.
And then when I saw it,
it was so big, I couldn't believe it.
I actually had
to do some checks
to see could this be real
or somehow did we mess things up.
It could only mean one thing.
There is water ice on Mars today,
and three is masses of it.
Boynton and his team have discovered
a vast area of ice in the southern hemisphere.
A froze ocean over 5000km wide.
There's plenty of water there.
What we found is just in the surface.
If we melted that, it would be enough
to fill Lake Michigan two times over.
There actually is probably a lot more
because we don't know how deep the ice goes,
that's just in the upper metre
there's that much.
It could be 10 metres deep,
it could be 100 metres deep.
There's a lot of ice there.
The ice they have found
is trapped in the ground,
a permafrost just like in Antarctica.
Crucially it's located at latitudes on Mars
where conditions are relatively mild,
where there's a real chance
of life surviving.
One of the most interesting things about this
is its not right up near the South Pole
or right not near the North Pole.
It actually goes down
to temperate latitudes.
It goes all the way down
to about 45° latitude.
This is like the equivalent
of Paris France on Earth.
This is really a place where it's much
more likely we can find life I feel.
But there was something even better.
Odyssey may not just
have found ice.
There may also be liquid water -
and that means there could be
living creatures there too.
Right now there might be
liquid water on Mars.
It's not going to be on the surface
but if we go down deep enough,
it's almost certain we will find
liquid water at some point beneath the ice.
It's all down to the interior
of the planet.
Scientists believe that Mars' heart may be
a great core of molten rock and metal.
At the very centre it could reach
temperatures of almost 2000°C.
This heat is spread outwards,
so that despite
the very cold surface of Mars,
just tens of metres down,
it may be warm enough to melt ice.
What Odyssey is seeing really may be
just the tip of the iceberg.
There could be, underneath that layer
of ice that it could detect,
a literal frozen ocean
of water beneath that.
Surprisingly there could be life today
on Mars beneath the ice in the liquid water.
So the Odyssey results
are also telling us
that we ought to reconsider
the possibility of life on Mars today,
search for it more vigorously
than we might have.
Odyssey's discoveries mean that there is now
a genuine possibility that there is life on Mars.
And if so, then we will soon have
to start reconsidering our place in the Universe.
Odyssey's discoveries
are so sensational
that scientists are beginning
to speculate
what strange creatures
might be there waiting for us.
What might an alien look like?
Would they, for instance, be based
on the same biological principles as we are?
When we look at life on Earth
we see that all life on Earth
uses the same chemistry
and the same genetic code,
the same hardware,
the same software.
It's really interesting to wonder
if life on Mars, if it started independently,
would it use the same code,
the same chemicals?
On Earth everything
is based on DNA,
but could it be that life on Mars
is completely different,
that there is an utterly
alien way of doing genetics.
Life on Earth is basically proteins and DNA,
so we can wonder if there's life on Mars
will it also be DNA and proteins,
the same type of DNA,
the same type of proteins.
One might think that DNA is
such a complex arrangement of molecules
that it's unlikely to have
the same set on another planet.
Equally, we may find
that DNA is also on Mars.
It may be that our way
is the only way of life.
On the other hand, we might argue
that DNA is optimal way to do it and that life
is going to discover this best possible solution
no matter where it starts.
So we're not sure
if life will be different or the same.
My guess is that
it'll be different,
and if life started
separately on Mars,
it will have a different genetic structure
than life on Earth.
But there will only be one way
to find this out conclusively.
To examine life in this detail,
someone will have to get up close.
We really have
to go find the facts,
and the facts are on Mars
and we've got to go find them.
We can hypothesise all we want,
but until we actually find the facts
on the ground, we won't know for sure.
It means that someone
will have to go to Mars,
and it just so happens that there is
an organisation already preparing to go…
Bo Maxwell is the UK President
of the Mars Society,
a group dedicated to colonising
our neighbouring planet.
Humans, by their very nature,
are explorers.
In our time we've travelled
from the African Rift Valley,
climbed mountains, crossed oceans and settled
just about everywhere there is to settle on Earth.
We've built our houses,
our towns, our cities,
and now the time has come
to move beyond the Earth
and Mars offers us the very best opportunity
to go to another world and settle somewhere else.
The Mars Society have their very own
low cost plan to get to Mars.
Bo is one of the masterminds.
He's working on it
from his home in Milton Keynes.
The aim of the Mars Society
is definitely to go to Mars.
We want to go there,
we want to explore and colonise.
The advantage of sending humans to Mars
is our greater ability to explore.
We are much more efficient
than robots.
Human beings have a tremendous
advantage over robot vehicles.
We have our own intuition,
our own intelligence
which leaves our robot vehicles standing.
A human being on Mars
can stand on the surface,
he can look around,
she can look around,
and instantly spot areas where life
may well be possible and life may exist.
The discovery of water ice on Mars
has reinvigorated their plans.
Water is the one thing
any colonisers would need.
Well hearing that Odyssey had found
subsurface water on Mars
was enormously exciting for somebody
who is involved in planning to send humans to Mars.
Water has a number
of important uses for us.
At the most basic, it provides
drinking water once it's been purified,
and it provides water
for hygiene purposes as well.
More important than that,
we can electrolyse it.
We can actually split it
into hydrogen and oxygen.
Oxygen obviously we can use
for breathing
and we can also use it as a fuel stock with
the hydrogen for our vehicle to come back home,
and we can also use the hydrogen itself
in fuel cells to power our rover vehicles.
So the ability to use water that exists on Mars
is tremendously important to human missions on Mars.
But any colonising of Mars
would require extreme action.
Some believe it would need
what scientists call 'terraforming',
transforming the entire planet
into an artificial Earth.
This involves growing plants
to create more oxygen, and an atmosphere.
It requires raising
the temperature of the planet,
raising the atmospheric density through melting
the icecaps and freeing up the carbon dioxide.
But the key thing about the water ice
on Mars is once we've done that,
then we can let that water exist free
form on the surface of the planet,
and it again will create
rivers, lakes, oceans,
which we can use
and the plants can use to survive.
But plants grown on Mars
may be very different from those on Earth.
The lower gravity on Mars,
one third of that on Earth,
means that both plants and animals
might grow taller and thinner.
I think we're all familiar with seeing
the giant redwood trees of California.
They're somewhat unusual
here on Earth.
They only occur
in a few localised places.
On Mars it will be the norm.
You would see these tremendously
tall, slim trees,
possibly with very high canopies
on them as well.
Animal life could be affected
the same way as well.
We could see new breeds
of animal that we haven't seen before,
very tall, thin sheep
living on Mars.
But again early days,
very much speculative.
This lower gravity would also have
implications for any people born there.
If humans live on Mars
for many generations,
they might develop into different forms
than humans on Earth.
They might be taller,
they might be thinner,
they might have
weaker muscles and weaker bones.
It might even be possible that they would not be able
to function very effectively on the gravity of Earth.
In that case, Mars' society
and Earth's society might split
and become effectively
two different species.
Of course, any terraforming
is still a long way off.
The next few expeditions to Mars
will definitely be made by machines.
NASA are sending two rovers capable of travelling
over 100 metres a day in search of signs of water,
while the Europeans
are sending the Beagle 2 probe.
Odyssey will continue to orbit Mars
to find out the extent of the ice.
Is it just in the southern hemisphere
or all over the planet?
Now we're starting to explore
what's going on in the north
and we're seeing
a very similar signal there,
but it's very likely we're going to find at least
as much ice in the north as we saw in the south,
and perhaps even more.
They also want to find out
how deep the water goes,
and whether there really are underground
lakes present as people now suspect.
The mounting evidence for water on Mars
means it's looking more and more habitable.
We may he approaching
an answer to the great question
of whether there's other life
out there in the Universe.
My guess is that if you have
the right ingredients life is inevitable,
but it's just a guess.
We have just one example
here on Earth.
We don't know for sure
if that's the case,
and that's why I want
to go to Mars, to test that guess,
to turn it from a guess
to a scientific fact.
My feeling is that it's likely
that there's life elsewhere in the Universe.
There are just so many other stars,
so many other planets.
It's hard for me to imagine that this is the only
life forms we have is what we have here on Earth.
100 years ago
some astronomers believed
that there were civilisations
on Mars with cities and canals.
They were wrong about the cities,
but the water is there,
so maybe the life is too,
after all.
But ultimately we may have
to go there to answer the question -
are we alone in the Universe?