We might not be alone in the Universe.
Scientists from all over the world
have their eyes and ears wide open
trying to detect signals
of life beyond our planet.
But we’re a bit tired
of just sitting and waiting.
So hop on our spacecraft,
because today you have
a very important mission.
To search for alien life.
So far, we've detected over
4,000 exoplanets in our galaxy.
And there may be as many as trillions.
To make your expedition easier,
you'd need to consult with NASA first.
NASA has developed the Confidence of Life Detection scale,
or CoLD,
to measure progress in life detection research.
The scale has seven levels,
ranging from signal detection to follow-up studies
once life beyond Earth is confirmed.
First, you'd need to look for biosignatures.
This is physical evidence of past or present life on another planet,
such as chemical compounds or molecules
that indicate biological processes.
If an alien astronomer was taking measurements of Earth,
they'd look for oxygen and methane.
Those are biosignatures that indicate life on our planet.
If you're a celestial technology geek,
you might scan for technosignatures.
These are signs showing the negative uses of technology
that cause artificial air pollution.
This means aliens could figure out we exist
because of all that smog we send into the atmosphere.
Embarrassing, right?
Now that you know what to look for,
where would you look for it?
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With so many courses to explore on Skillshare,
maybe those aliens will contact us instead.
You could start this search in our own cosmic backyard.
Alien life could be hiding on the subsurface oceans of Europa,
one of Jupiter's moons.
Or deep beneath the surface of Mars.
Ground telescopes have already detected methane on Mars,
sending probes to measure surface levels.
That already puts you on the second level of the CoLD scale.
Or you could go further and look for alien life
on rocky planets outside our Solar System.
You'd need to locate planets orbiting a star in its habitable zone.
That’s the area where a planet is not too close to the star and not too far,
allowing for temperatures to be just right for liquid water to form.
Scientists have already done the hard work for you here.
Using the Kepler Object of Interest Exoplanet Archive,
researchers identified systems
that might have rocky planets that meet the criteria.
They found 24 super-habitable planets.
And one of them is very promising.
KOI-5715.01 is roughly one billion years older than Earth,
which means it's had enough time for life to develop.
Scientists estimate that the best chance of discovering life
is on planets between 5 and 8 billion years old.
That makes KOI-5715.01 a perfect candidate.
While it’s a bit cooler than our planet,
it could support life if it contained enough greenhouse gases.
So let's say you detected biosignatures on KOI-5715.01.
Now you've got yourself a potentially habitable exoplanet.
NASA would then have to confirm that there were no measurement errors
and that the planet really has the potential to host life.
The next step would be to predict
what type of source could generate such a signal.
Scientists would need to confirm this signature couldn't have come
from a non-biological source.
Once that was done, you'd be on level 4 of the CoLD scale.
At this level, scientists would test the signal
with other advanced measurement methods.
NASA’s powerful James Webb Space Telescope
would confirm the exoplanet contains a strong signature for life.
And you would be able to proudly say
you found alien life.
And then scientists would be able to kickstart follow-up studies at level 7.
That means you'd now be ready to fasten your seatbelt
and see these aliens for yourself.
But how would you get there?
Yeah, that’s when things get tricky.
KOI-5715.01 is located almost three light-years away from us.
That’s 700 times further away than Proxima Centauri,
the closest star to our Solar System.
If we used developing ionic propulsion engines,
it would take over 55 million years to get there.
“Wow.”
You'd have to make use of some futuristic solutions.
Like a laser sail.
This technology uses ultra-thin mirrors
to capture the momentum of light from stars
and then uses this momentum to push a spacecraft to high speeds.
If you managed to build laser sails with diameters of 320 km (200 mi),
you might be able to reach KOI-5715.01 in about 8,500 years.
Setting aside the fact that you wouldn't live that long,
what would you find once you got there?
Alien life could be extremely complex or very basic,
and the alien’s appearance would depend on the world they evolved on.
Things like gravity, density and the amount of energy given off by its star.
They would probably have something that resembles
fingers or tentacles to build tools.
And since two legs and two arms
are more efficient than four legs,
the aliens might have evolved to walk upright.
You wanna invite them for a stroll?
Well, first you’d need to figure out their form of communication.
And it might be a little more advanced than speech or writing.
They might just exchange pheromones, or even use telepathy.
And finally,
you do wanna know how they reproduce
We can’t be sure if alien reproduction happens by seeding,
fission or egg-laying.
So it’s best to leave the romantic stuff here on Earth.
While your journey to find alien life
might be successful in our hypothetical story,
in reality, it's still very far-fetched.
With technology evolving to detect signals from outer space,
we might be able to identify them at some point.
But there would still be the issue of getting to them.
What good does it do knowing something is out there
if we can never see it up close?
I mean, unless aliens were already living inside Earth.
But that sounds like a story
for another WHAT IF.