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60 years ago this month, in January 1958, the United States launched its first satellite, Explorer 1.
It started a legacy and launched the longest-running space exploration program in history, so you’d
think making it would have been part of some big plan figured out years in advance.
But... nope.
Instead, Explorer 1 and the modified rocket that launched it were finished in just 84 days.
And we had a lot to figure out in those three months.
But somehow, we did it.
Like most of America’s early space program, Explorer 1 was a result of the Cold War struggle
with the Soviet Union.
In October 1957, the Soviets launched Sputnik, the world’s first satellite.
And what did the US do?
It freaked out.
Like, seriously panicked.
In the race to claim the high ground of space, America was clearly behind.
To make matters worse, when the US attempted to launch its first satellite that December,
it failed just over a meter off the launchpad.
Newspapers called it “Kaputnik”. Ouch.
Since NASA didn’t even exist yet, coming up with a successful -- and fast -- response
to Sputnik fell to the US Army Ballistic Missile Agency and the Jet Propulsion Laboratory,
better known today as JPL.
And in an incredible feat of engineering, Explorer 1 launched not even three months later.
Take that, Kaputnik.
But that’s definitely not how things were supposed to happen.
As a show of peace, the US had long planned to launch their first satellite on top of
a modified sounding rocket.
Sounding rockets are used mainly to help study the Earth’s climate, so this would be a
clear signal that this was a mission of science, and that we weren’t trying to start an actual
war with the Soviet Union or anything.
But after that first failure, the Army just needed something that would work, so they
turned to the Jupiter-C rocket, which was used as a test platform for intermediate-range
ballistic missiles.
Also, the rocket that launched Sputnik was a modified missile, not a sounding rocket,
so the show of peace seemed less important by that point.
Even though it had three stages, or segments -- which these days is more than enough to
launch satellites -- the Jupiter-C wasn’t powerful enough to put something into orbit,
so the Army did the only thing it had time to do: duct-tape on a fourth stage.
Well, not literally.
But adding another stage did make the setup seem kinda ridiculous.
It was a like building a triple-decker bus.
Like, sure, it’s possible to do that, but it’s not exactly the most, like, elegant
solution, and it can create more opportunities for things to go wrong with computers or engines.
For comparison, most rockets today usually only have two or three stages.
And much better computers.
But even with all that, the satellite itself still had to be really small -- just 14 kilograms,
or about as much weight as a beagle.
And about 40% of that weight was needed for its battery, which didn’t leave a lot of
weight for other things.
So the engineering team had to get creative.
To relay data back to Earth, they equipped the satellite with an innovative antenna system.
And by “innovative”, I mean really weird.
It consisted four wire “whips”, which extended into a large transmitter as the spacecraft
spun along its axis.
Also, in order to keep the radio and other instruments from getting too hot or too cold,
Explorer 1 needed a temperature control system, but without the weight of fancy radiators.
So what did JPL do?
They painted the spacecraft in stripes of white and green.
Since different colors transmit different amounts of heat, the area of white versus
green could be tuned for just the right equilibrium temperature.
On January 31st, 1958 -- 119 days after the launch of Sputnik 1 -- all this was put to the test.
And it worked!
Getting into space was a big enough accomplishment, but Explorer 1 also performed pioneering scientific
experiments in orbit.
For one, it carried a Geiger counter to make the first direct measurements of the radiation
environment in outer space.
At times the counter registered so much radiation that it overwhelmed the sensors -- which baffled scientists.
Eventually, they figured out this was the result of radiation trapped by Earth’s magnetic
field, regions we now call the Van Allen Belts after the leader of Explorer 1’s scientific
investigations.
The mission also carried a pair of experiments designed to measure the rate at which micrometeorites
strike the Earth.
One consisted of a wire grid mounted on the outside skin of the spacecraft.
If a small particle struck the grid, one of the wires would break, altering an electric circuit.
The other was a microphone inside the spacecraft that listened for the “plink” of a particle
striking the hull.
Over about a day, it picked up 145 impacts, giving scientists their first direct measurement
of natural space debris.
None of this seems exactly hi-tech, but hey, it got the job done.
Even though Explorer 1 only lasted a few months, it began a program that continues today.
In 2013, NASA launched a spacecraft to study the atmosphere of the Sun.
It was called IRIS, but its official record lists it by another name: Explorer 94.
In the next couple of months, NASA will also launch ICON and GOLD, two Explorers that will
study part of Earth’s upper atmosphere.
And this year, they’ll also launch TESS, which will search 200,000 nearby stars for exoplanets.
By the early 2020s, we’ll probably even see the launch of the 100th Explorer mission.
Although they’ve each had their own goals, all the missions in the Explorer program have
followed in the footsteps of America’s first satellite from 60 years ago.
And one thing’s for sure: We’re definitely a lot better at building satellites than we
were in 1958.
Thanks for watching this episode of SciShow Space!
If you love learning about space history, news, and other weird things in the universe
as much as we do, you can go to youtube.com/scishowspace and subscribe.
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