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And the pin this month features the rocket from this video!
[♪ INTRO]
“T minus 10, 9, 8…”
Pretty much every time you’ve heard that famous countdown,
the next thing that happens is a giant rocket ignites and launches into space.
When the skyscraper-sized Saturn V that took Armstrong, Aldrin,
and Collins to the moon lifted off, it weighed 2.8 million kilograms.
Give or take a bit, depending on what the astronauts had for breakfast.
When the astronauts came back,
the capsule that splashed down in the Pacific weighed under 5000 kilograms.
So what happened to the other 99.8% of that takeoff mass?
Well, more than 90% of that total was fuel and oxidizers.
But everything else got left somewhere along the way,
destined to burn up in the atmosphere, float in deep space,
or freeze on the surface of the Moon.
That’s not a terribly efficient way to go about things.
So for a long time, engineers have wondered if it was possible to reuse rockets.
But while it’s certainly less wasteful,
reusing space vehicles is also easier said than done.
Rockets are objects that shoot mass in one direction in order to go the other way.
The more stuff you throw out the back, the faster you’ll go.
While rockets as a technology have been around for at least a millennium,
there’s a very good reason the first ones weren’t reusable: they couldn’t be.
That’s because, for centuries, rockets were built to explode, for show, or for war.
Most historians place the invention of the first rockets in medieval China
around 1200 CE, for use in fireworks and warfare.
Fast forward to the mid-20th century and
rockets saw a lot of progress as weapons.
The good news is, after WWII, we started seeing them as tools of exploration.
And once the goal became something other than to blow up, engineers started
seeing the sense in reusing the same rocket instead of making a fresh one.
The simplest way to use a rocket again would be to
design a single-stage-to-orbit vehicle.
You’ve got one vehicle, it flies to space, and then it comes back.
You can even see this in old-timey sci-fi where rockets land and take off again.
While this would make a lot of sense in theory,
in practice it proved nearly impossible.
That’s because of the “tyranny of the rocket equation,”
which happened to be my band name in high school.
Every gram of mass you want to launch to space needs fuel to send it there,
and that fuel then also needs to be launched up, and so on.
This is why 90% of the Saturn V’s weight was fuel and oxidizer.
There is kind of a cheat code, though, known as staging.
If you jettison the tanks that hold fuel as you use it up,
known as stages, you no longer have to carry those empty tanks.
That makes the next part of your journey more efficient,
since the rocket gets smaller as it goes.
So the only way we’ve been able to reuse rockets to date
is to go with partially reusable rockets.
We’ve had success with both reusable booster stages and reusable orbiters.
During the space race of the 50s, 60s, and 70s,
many ideas just weren’t technically feasible.
The time pressure pushed the USSR and the USA
to make ‘em fast and send ‘em up.
So reusables were largely out of the question at the time.
Attitudes shifted, however, once the goal became
to build a space station up there, instead of just getting to orbit or the moon.
The first major success for reusable technology was the Space Shuttle.
It had boosters and a big fuel tank that would be jettisoned along the way.
The boosters were recovered and many parts were re-used for the next launch.
The orbiter would come back down after its mission and land like an airplane.
The external fuel tank (that huge orange thing) was the only part that would be
irreparably damaged after it separated
from the orbiter and re-entered the atmosphere.
The five fully operational shuttles flew a total of 135 missions,
although two were lost in tragic accidents.
Lots more interest has picked up around
reusable rocket stages as better technology has developed.
In 1996, the X Prize Foundation put up 10 million dollars
for the first non-governmental group to launch a crewed vehicle to space
twice in two weeks, though technically they just had to go 100 kilometers up.
In 2004, just eight years later, a group succeeded and won the prize.
Their design was essentially a plane that would fly up to the top of the atmosphere,
and a rocket would briefly push it over the
100 kilometer mark before it came back down.
Richard Branson and Virgin Galactic licensed
the technology and turned it into their SpaceShips.
Blue Origin, a company owned by Amazon’s Jeff Bezos,
has since also succeeded in building reusable rockets
that can go up above this 100km line and come back down.
But going straight up and down isn’t enough to resupply the Space Station
or place satellites in orbit. It’s basically just bragging rights.
To do anything worthwhile, you need a lot more horizontal momentum.
SpaceX has developed powerful rockets that can get their payloads
into low Earth orbit, about 400 kilometers up.
Meaning they can reach the Space Station,
and do other generally useful stuff like launch satellites.
The rockets autonomously return to Earth, although there were
plenty of spectacular crashes during the development phase.
Getting to space is difficult, and getting the same vehicle
to do it more than once is asking a lot.
But if you can manage it, you can significantly reduce costs.
It’s also just less wasteful!
And despite a lot of progress in the last twenty years,
we’re still a long way off from the
single-stage-to-orbit dream of the first rocketeers.
This year on SciShow, we’re bringing more space to this space.
That means more rocket videos like this, new faces like mine that you might have
seen on the SciShow Space channel, and more frequent space themed videos
about everything from the inside of the moon to our last solar eclipse.
Each month, we’ll talk about another rocket and have a cool new pin to
celebrate the subject of the show.
This time around, we’re celebrating rockets that can do their jobs more than once.
So grab this month's pin at DFTBA.com/SciShow and say,
"Hello!" to more space at SciShow!
It’s gonna be stellar.
[♪ OUTRO]