There’s been a lot of talk about starships over the last week or so.
You know: exploring strange new worlds, seeking out new life, and all that.
And all thanks to a new engine that’s stumping scientists.
Back in 2015, Hank took a trip into the SciShow Space Debunker, where we explored the rumor
that NASA had created an EM drive, or an electromagnetic drive.
It’s a propulsion system that doesn’t need any propellant, and in theory, the technology
could get you to Mars in only 70 days.
Problem is, it also seems to violate the laws
of physics.
Back then, other labs had created EM drives and reported that they generated a tiny amount
of thrust, but nothing had been peer-reviewed.
And there was no official report that NASA had made their own EM drive.
But a year and a half later, it’s official: NASA has actually created an EM drive.
And it seems to work.
The peer-reviewed paper, which was published last week in the AIAA Journal of Propulsion
and Power, comes from researchers at Eagleworks, a lab at NASA’s Johnson Space Center.
Instead of the usual rocket fuel, the EM drive works by bouncing microwaves back and forth
in a cone-shaped chamber.
The waves start in the narrow end of the cone, and eventually generate thrust toward the
wider end to move the spacecraft.
Which is really cool!
Except, according to Isaac Newton, it should also be impossible.
Newton’s Third Law of Motion says that every action has an equal and opposite reaction
-- so when the microwaves hit the chamber, the chamber should push back, and the spacecraft
shouldn’t go anywhere.
Right now, no one is actually sure why the EM drive works, but the researchers think
it could have something to do with the pilot-wave theory of quantum mechanics.
According to the traditional, mainstream model of quantum mechanics, particles don’t have
a definite location until you observe them.
But according to pilot-wave theory, particles always have a definite location.
It might sound simple, but it has a lot of weird implications -- like that vacuums, which
are supposed to be empty, must be filled with some kind of quantum field.
There isn’t much support for the theory, but if it is true, it would mean the microwaves
in the EM drive could sort of bounce against the vacuum.
The force between the waves and the chamber wouldn’t cancel out, so Newton’s Third
Law wouldn’t be violated.
If that sounds vague and complicated — well, it is.
Even the NASA researchers aren’t sure how it really works, and pilot-wave theory is
just one idea.
They have done tests to make sure nothing is interfering with the drive, though -- like
running it in a vacuum to make sure air molecules weren’t getting in the way.
So, no one really knows what’s going on, but it looks like the technology is legit.
It still has a long way to go before it could possibly be useful, though.
Right now, the drive produces about 1.2 millinewtons per kilowatt of thrust.
Compare that to the Hall thruster, which accelerates ions to move spacecraft through deep space
and is a serious contender for Mars missions.
It generates about 60 millinewtons per kilowatt.
So even though the EM drive is lighter and might be easier to manage, we’ll need a
much more efficient version before we can use it to zoom around the galaxy.
. . . . . .
Meanwhile, Elon Musk continues to make us all wonder if there’s anything SpaceX can’t
do.
In September, the company announced big plans to colonize Mars -- but while they’re working
on that, they’ll also be trying to deliver satellite internet to the entire world.
Last week, SpaceX filed an application with the United States Federal Communications Commision
to launch 4,425 satellites into Earth’s orbit for a global internet service.
And if you think that seems like a lot of satellites, you are right.
Right now, there are only around 7500 satellites in orbit, meaning SpaceX hopes to increase
that number by 50% all by themselves.
This puts SpaceX on a growing list of companies, like Facebook and OneWeb, that are trying
to bring the internet to everyone on Earth -- including the billions of people who don’t
have access to the internet right now.
With traditional internet, the signal travels along wires from your phone or cable provider
to your modem.
Satellite internet, on the other hand, sends the signals between a dish on your roof, a
satellite in orbit, and a larger dish at a ground station.
Satellite internet doesn’t require any cable or phone networks, so it’s great for rural
communities, but it also takes a while for the signals to bounce back and forth.
Other companies are already providing satellite internet to some of the world, but SpaceX’s
network will be faster and more accessible.
For one thing, their satellites will have much lower orbits -- around 1100 to 1325 kilometers,
which will cut lag times down to 25 to 35 milliseconds since the signals don’t have
to travel as far.
For comparison, the company HughesNet has satellites orbiting around 35,400 kilometers
up with lag times of 600 milliseconds or more.
The planned SpaceX network will be at least 17 times faster.
SpaceX also promises download speeds up to 1 gigabit per second, which is 100 times faster
than other networks, which offer around 10 megabits per second.
If their application is approved, SpaceX will still have to build the satellites and ground
stations, but satellites could potentially start launching as soon as 2019.
Which means that pretty soon, a lot more people could have access to the internet — all
thanks to a little rocket science.
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