Imagine that the Sun
is on the verge of exploding.
Or that a planet-killing asteroid
is headed our way.
Or maybe
you just want to take the entire planet
on a joy ride around the Universe.
Well, fasten your seatbelts.
Let’s pilot Spaceship Earth
out of our Solar System.
It’s not totally surprising
why many people refer to our home
as Spaceship Earth.
This giant object carries a crew of eight billion,
travels through space at 108,000 km/h (67,000 mph)
and comes equipped with some pretty incredible oxygen,
water and food production systems.
But just moving in one direction around the Sun
year after year gets a little boring.
If only there were ways to get this nearly 6 billion trillion metric ton vessel
to a high enough velocity
that it could escape its orbit
and the Solar System once and for all.
All we'd need to do is crank up Earth’s speed to 151,000 km/h (94,000 mph).
We’ll try a few conventional methods,
as well as some that might surprise you.
And hopefully we won’t completely destroy the whole planet in the process.
“I don’t wanna die.”
The most obvious way to do this
would be the one most widely used today for propelling spaceships.
Chemical rockets.
Launching one single 500 metric ton rocket
kick-started by a chemical reaction into space
could use as much as 112,000 kg (29,600 gallons) of fuel.
So the amount you’d need to launch Earth out of orbit would be,
well, simply out of this world.
To escape our Sun's gravitational pull,
you’d need the thrusting power of billions upon billions of rockets.
And powering these rockets would require so much material
that our planet would nearly disappear.
I mean, would it be worth the effort
if you were only left with 15% of the Earth that you started off with?
For this, you'd need to jump on board a concept that’s only a work in progress.
Earth's trip would be powered by the same process
that powers our own Sun.
Instead of chemical reactions,
fusion rockets would rely on the nuclear fusion
of two or more hydrogen atoms to form helium.
At the very least,
these rockets would be twice as efficient as chemical rockets.
They would make space missions to Mars about half as long.
And the journey from Earth to Jupiter
could be as short as two years.
Efficiency aside,
it would still require enormous amounts of fuel
to move any object as big as ours.
On the bright side,
if hydrogen was your only fuel source,
at least it would be widely available throughout space.
The next option
would be a strong contender for powering Spaceship Earth,
if you don’t mind a slow and steady wins the race mentality.
An electrostatic ion engine
works by taking accelerated positive ions
and ejecting them at high speeds.
One ion engine would deliver
about 10 times more thrust compared to a chemical rocket.
And while a chemical rocket
could only burn for a few minutes,
an ion engine could be steadily powered for months,
even years.
Now, the tradeoff is slower acceleration,
but this would eventually see Earth reaching the velocity
we’d need to escape the clutches of our Sun.
Maybe what you really need to power Earth through the galaxies
would be a traditional renewable energy source.
So why not imagine that you could propel
your massive spacecraft using solar power?
Solar sails would essentially work just like sails on a boat.
Except instead of wind,
huge reflective sails
would capture the momentum of photons emitted by the Sun and other stars.
As long you don’t run out of light,
you'd keep moving.
This is based on the principles behind LightSail 2,
a mission that was launched in 2019.
The vessel used a sail about as big as a parking lot.
And it reached the speed of an airline jet
after one month of constant sunlight.
But keep in mind that LightSail 2
only has a mass of 5 kg (11 lb) and is only trying to stay in orbit.
Imagine how huge a sail you’d need
to move the entire planet.
And not only that,
but you’d be at risk of losing velocity
as fewer and fewer photons hit the sail between stars.
So maybe light
wouldn’t be the primary fuel source you’d want
to power Earth through the Universe.
You could power our massive spacecraft
using the gravity of other objects in the Solar System,
like planets, asteroids or comets.
You could increase,
decrease or change the direction of Earth’s velocity
by slingshotting around these objects.
This is exactly what the Voyager 2 space probe used
to escape the Sun's gravity and leave the Solar System.
But to do the same for Earth,
you’d have to start by deflecting large rocky objects
from the outer regions of the Solar System toward us.
As they approach,
their orbital energy would decrease and ours would increase,
moving us further away from the Sun.
But in order for this to work,
these objects would need to basically brush right up against Earth’s atmosphere.
And they would need to be big.
Maybe up to 10,000 times bigger than what hit Earth millions of years ago
and wiped out the dinosaurs.
So while this would be another great way to increase the speed of Spaceship Earth,
one small miscalculation
could lead to the death of every living thing trying to enjoy the ride.
Maybe we’d be better off
if Earth wasn’t a spaceship you could control
but a rogue planet moving freely through the Solar System and beyond.
Well, that’s a story for another WHAT IF.