Just north of the Martian equator
lies a 45 km (28 mi) wide impact crater
that scientists believe
may have been the site of an ancient lake.
Here at Jezero Crater,
scientists theorize that its frozen soil
may contain the most significant discovery
of humankind,
life.
On February 18th, 2021,
NASA's Perseverance rover
started searching this crater
to find out
if we're truly alone.
As Scientific American puts it,
"it would take a near miracle
for Mars to be sterile."
Astrobiologist Chris McKay at NASA
believes that Earth and Mars
have been sharing materials for billions of years.
Kind of like using your roommate's spice rack.
What? I thought you said it was communal.
Comets or large meteorites that have hit Earth
may have also sent debris onto Mars.
A tiny fraction of this debris on Mars
could have carried the same microbes
that kickstarted life as we know it on Earth.
But what would this alien life look like?
Many scientists agree that
whatever life on Mars we might find
would need to be incredibly robust.
With the combination of radiation
and freezing temperatures on Mars,
could any lifeform survive
such a harsh environment?
As far-fetched as it sounds,
microbiologists have discovered
many organisms that thrive
in extreme environments.
The tardigrade, or water bear,
is a highly resistant extremophile.
It can withstand heat,
cold,
pressure,
radiation,
and even a complete lack of oxygen.
There are also certain types of bacteria on Earth
that rapidly produce spores
when faced with hazardous conditions.
The bacteria can then hibernate
during an extended period of drought
and withstand intense ionizing radiation.
A team of over 1,000 geologists, chemists,
physicists, and biologists worldwide
have drilled 4.8 km (3 mi) into the Earth
and discovered robust lifeforms.
Mars has a similar geological past to Earth.
So looking underground
could be a great place to start.
By drilling into the Jezero Crater,
we could encounter spores associated
with a relatively recent geological era.
And on future missions to Mars,
we may dig deeper
and uncover fully vegetative microbes.
To find rock samples that might support life,
NASA's Perseverance rover
uses an array of lasers,
called a SuperCam.
It can study the surface of Mars at a distance.
One of the lasers will heat a rock sample
and vaporize it.
This creates a plasma
that can be analyzed
to understand its elemental composition.
Another laser will reveal
which compounds are in the dirt.
If the SuperCam detects organic molecules
or elevated concentrations of elements
like nitrogen or phosphorus,
the rover will head over to take a closer look.
It will then scan the soil in greater detail
to detect any organic material hiding in the dirt.
NASA's team on Earth only has one shot
at picking the right spot
to gather these samples.
With limited space onboard the rover,
only a few dozen samples can be collected.
So no pressure, and uh, fingers crossed.
If all goes well,
NASA plans to bring back samples
known for preserving biosignatures on Earth.
Biosignatures are faint molecular traces
left behind by microbes billions of years ago.
Once the samples are collected,
NASA and the European Space Agency
plan two missions to get them back to Earth.
This involves blasting tubes
of rock and soil samples into orbit
to be collected by another spacecraft
and then returned to Earth.
Woah, this looks kinda fun.
If Perseverance's mission is successful,
the discovery of life on Mars
would be as groundbreaking
as the discovery of DNA.
In 1543, Copernicus boldly shook the status quo
with his theory that the planets orbited the Sun.
His discoveries
completely changed our worldview,
no longer putting Earth
at the center of the Universe.
Discovering life beyond Earth
could be just as powerful.
But not finding any life
could raise more questions.
Is the Earth truly special?
Are we alone out here?
Even if we don't discover life,
these Martian rock samples
will allow chemists to study the geochemistry,
mineralogy,
and foundational bedrock materials
of Mars in detail.
This could provide us with essential insights
into the climate history of Mars
and help us better understand
Earth's climate as well.
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In 1976,
two Viking landers
became the first spacecrafts from Earth
to touch down on Mars.
They too probed for life in the Martian soil,
and the results are still debated to this day.
One experiment indicated that
the Martian soil tested positive for metabolism.
On Earth, this would almost certainly suggest
the presence of life.
But another related experiment
found no trace of organic material whatsoever.
While most scientists
have not reconciled the conflicting results,
the consensus is that
there is no conclusive evidence of life on Mars.
But several researchers disagree.
Recent discoveries
of terrestrial microorganisms
surviving outside of the ISS
indicate that life may be
resilient enough for Mars.
And methane in the Martian atmosphere
could be a sign of microbial methanogens,
a type of microorganism that produces
a significant amount of methane.
Stinky aliens.
Mind you, it's possible that life on Mars
didn't have the right conditions to start at all.
Or maybe it died off from an extinction event
similar to the asteroid that
wiped out the dinosaurs.
Or it's even possible that we might end up
finding life that was accidentally brought to Mars
by one of our many rovers.
Let's hope this Perseverance mission
doesn't turn into a 2.7 billion dollar face-palm.
If Mars is your bag,
well, have you ever thought about
setting up shop there?
With recent developments in rocketry,
colonizing Mars
might be possible in our lifetime.
You better strap in because
that's a story for another What If.