- So, according to the
astronomer Phil Plait,
an asteroid just six
miles wide is big enough
to completely wipe out humanity.
Yep.
Now imagine astronomers today discover
that a planet-size killer asteroid
is just bearing down on the Earth.
Could we stop it?
How?
- [Voiceover] It's the
only way to be sure.
- One obvious choice: the nuclear weapons.
Let's just nuke it from orbit, right?
But this time it’s not
the only way to be sure.
Because, you see, hitting
an asteroid dead-on
with a nuclear warhead
might just break it up
into smaller fragments
that still hit the Earth
at multiple points.
So a better idea might be
for us to detonate a nuke
near the asteroid and push
it to one side or another
so its trajectory changes
and it completely misses our planet.
There's an even more old-fashioned idea
than nuking something,
and that's kinetic impact.
Essentially, you deflect
the incoming object
by slamming another
incoming object into it.
Scientists have done this before.
You guys, in 2005, the
"Deep Impact" mission,
I see what you did there, NASA,
altered the trajectory
of a comet by hitting it
with an 816-pound probe
flying at five miles per second.
There're the more laid-back ideas.
I mean we could just let the
sun blow the asteroid away.
You see, a solar sail takes
advantage of radiation pressure:
that slight push of the sun’s energy
against a reflective surface.
If we have enough lead time,
we could send out probes
to cover the asteroid
with mirrored sails,
foil or reflective paint
and then let the sun
just sort of push it away
over the course of several decades.
Researchers in Beijing came
up with this plan in 2011
to redirect the Apophis asteroid.
Now here's something.
I mean you already know this.
All objects with mass have gravity,
even an object as small as a spacecraft.
So if we put a heavy enough
probe in a close enough orbit
around an asteroid, the
gravity of this probe
would slowly pull the asteroid off course,
like a tractor pulling a heavy
trailer, a gravity tractor.
That's the name of it.
British company EADS
Astrium started developing
one of these probes in 2009.
But just remember, this
method also depends
on a long forewarning before collision.
There's another idea.
Many asteroids contain
frozen substances, right?
So with some intense heat
these can be made to melt,
or evaporate.
By aiming a high-powered
laser or focusing the sunlight
with angled mirrors at
one side of the asteroid,
some scientists think they
can cause frozen parts
of the asteroid to erupt into gas jets
that will act like rocket propellant,
pushing the asteroid in
the opposite direction.
Pretty clever, huh?
I mean if it works.
Thanks for watching.
Check out our article on howstuffworks.com
to learn more about saving the
planet from killer asteroids.
But enough about us.
What do you think is the best
way to stop a killer asteroid?
Let us know in the comments
and be sure to subscribe
for more What The Stuff.
(bang)
