ENG: The Space Shuttle Program
Updated: Jul 8, 2020
Hello everyone, David here for my first full-length engineering/aerospace post! Today's topic will be what is probably the symbol of space exploration, an engineering miracle so beautiful in its philosophy yet so efficient in its missions: the Space Shuttle.
We have a few things to cover here, so let's get right into it.
The History of the Program
The Space Shuttle Program was born in 1972, the same year that the Apollo program officially ended after the American government realized there was no point on going to the moon, as the U.S had already established superiority over its space race adversary, the U.S.S.R., besides, it was kinda... expensive. The Saturn V cost about 187 million dollars, and none of its parts were reusable. As Elon Musk put it, when talking about the advantages of reusable rockets over "disposable ones", it was like building a Boeing 747, making it fly once and then just throwing it away.
With all that being said, NASA was looking for a reliable yet efficient platform of putting American astronauts into space while also being able to carry big payloads with them, as the idea of a bigger, international Space Station was already falling upon the rocket community.
Their idea was fantastic: a vehicle that would launch like a rocket and land like a plane, the Space Transportation System (STS), which would later be known as the Space Shuttle, was to be NASA's gateway into space and beyond.
The first shuttle to be constructed was called Enterprise and did not contain the main engines as it was built to be a test plane for the following missions. Enterprise was put on the back of a Boeing 747, taken to a high altitude and then released, landing successfully after gliding for about 5 minutes. Several test missions ensued, in which NASA got a grasp of what it was like to fly and land the Space Shuttle, making adaptations on the vehicle if needed.
After the success of these missions, NASA decided to take a step further and build the first-ever completely designed, full-flight capable Space Shuttle: Columbia. It was launched on April 12th, 1981, on the STS-1 mission, where it successfully launched, achieved orbit, and eventually deorbited back to earth, where it glided its way back to the airbase, landing gracefully.
Following the success of the STS-1 mission, NASA continued with the program, sending dozens of satellites, both scientific and military, as it also expanded its Space Shuttle fleet, adding the orbiters Challenger, Discovery, and Atlantis to their "collection".
The program was a success and everything was going as planned, until a disaster happened. On January 28th, 1986, Space Shuttle Challenger was to launch for the STS-51-L mission. Aboard the vehicle were 6 NASA astronauts, and a high school teacher named Sharon Christa McAuliffe, who was going to be the first teacher in space, where she would transmit two lessons to their students down on Earth. However, during launch, the Shuttle’s right SRB (Solid Rocket Booster) started smoking, and two seconds later an explosion took place, destroying the whole rocket, killing all 7 crew members aboard.
A later investigation concluded that a hole had erupted from the SRB, and strong wind shears further damaged the vehicle, allowing for an uncontrolled ignition due to the open hole, which led to the explosion that ended the lives of 7 genius minds, along with the orbiter carrying them to space.
The disaster put the so far flawless program on hold for two years. It was decided that it was to continue, however, this time with security measures doubled. And so it did, with the construction of yet another vehicle, Space Shuttle Endeavor, replacing the destroyed Challenger.
Several of successful missions took place after the disaster, including the launch of the Hubble Space Telescope by Space Shuttle Discovery and its crew, on April 24th, 1990.
Another huge contribution from the Space Shuttles was the construction of the International Space Station. In total, over 30 missions were conducted related to the construction or supply to/for the I.S.S, although another tragedy struck in between flashes of happiness for the successful missions.
On January 16th, 2003, Space Shuttle Columbia launched successfully carrying, among other things, the first Israeli in space, Ilan Ramon. During reentry, however, the Space Shuttle disintegrated and killed all seven crew members, putting the Program on another 2-year hold, resuming then activity for another 6 years.
Finally, on July 8th, 2011, Space Shuttle Atlantis was the last to reach for the skies during the STS-135 mission, putting an end to the overall successful program, accompanied by two unfortunate tragedies along the way. There are a lot of reasons for the cancellation of the Space Shuttle Program, the main of which being a White House administration team change, because, remember, NASA is intrinsically a government agency, not a company, therefore political instability can put programs on hold to diverge budgets and things like that. Besides, the government wanted to start thinking about a crewed program to bring humans back to the moon and wanted to have a budget for that. Although the latter was merely an outshined star of an idea, it is today becoming reality, with the Artemis Program, that aims to put humans on the surface on the moon again by as close as 2024, but that could be a whole other post as there are a lot of things to talk about.
The Space Shuttle Program was a great advance in technology, widening the view of what we thought could be achieved by our own engineering. It was, however, the last time Americans launched to the ISS from American soil, aboard an American vehicle, and during the ensuing years, the U.S had to rely on the Russian Space Program to send astronauts to the ISS, aboard the beautiful, incredibly reliable Soyuz. With SpaceX and their Falcon 9/Dragon Crew Capsule, that is about to change… tomorrow! (probably). I will make a post about this so don’t worry, but stay tuned for the May 27th launch as it will be a historical launch!
To finish, let’s take a look at how the shuttle actually works!
An Anatomy of the Space Shuttle
The Space Shuttle is composed of three main parts: the orbiter, the main liquid fuel tank and the SRB’s. Let’s first talk about the orbiter
The orbiter is the vehicle itself, the Shuttle, the main star. On the outside, way down, there are three Space Shuttle Main Engines (SSMEs), called RS-25, that provide thrust for the launch, orbit insertion and deorbit burn, being fed liquid hydrogen and liquid oxygen (LOX). Each of those bad boys produced 1,859 kN, or 418,000 pounds, or 189.6 tons of thrust during liftoff, which is… well, a lot of thrust. On the inside, the vehicle contained a flight deck, a mid-deck, and a utility area, as well as an airlock located in the mid-deck that led to the payload area, where up to three astronauts would depressurize before exiting the vehicle and repressurize when the job was done.
The payload (or cargo) bay could carry up to 24 tons of cargo, which was one of the best things about the whole Shuttle, as it was crucial for the delivery of whole nodes of the ISS and other heavy cargo.
The SRB’s, or Solid Rocket Boosters, are essentially the biggest source of lift during launch. They are what power the Shuttle through the thick atmosphere, away from the powerful gravity, providing crucial boost (hence the name) of incredible magnitudes. Each of the SRB’s produced 14.7MN, or 3,300,300 pounds, or 1500 tons of thrust, which is insanely powerful. They are the most powerful SRB’s ever flown, however, it was as heavy as it was powerful, that’s why it was detached from the aircraft when its fuel depleted (therefore not serving as dead weight). They did open parachutes and land in the Atlantic and were actually “refueled” and reused. A bad thing about the use of SRB’s are their uncontrollable nature: they are not fed fuel, as a matter of fact, they burn what is pretty much some sort of powder, so that they can fill as much “fuel” as they can in the booster. Because there are no pumps or valves, the amount of “fuel” (quote on quote because it is a powder, not fuel) being combusted can not be controlled, in other words, when the SRB’s are ignited, nothing can stop them. You can see that by looking at the Challenger disaster video, as even after the main fuel tank exploded, the SRB’s kept flying upwards, uncontrollably, until they crashed in the Atlantic.
Finally, the main fuel tank, i.e, the external tank, was the one who fed the three RS-25’s during launch. It contained liquid hydrogen fuel and liquid oxygen (LOX) as the oxidizer and was jettisoned soon after MECO (main engine cut-off), when it would burn up in the atmosphere during reentry. In the first few flights, the tank was white just like the Shuttle, however, later on NASA started applying foam insulation spray on the outside, where it received its orange color, becoming a symbolic aspect of the Space Shuttle.
Well, folks, that was it for today's post! Sorry about the late time, I was just filled with stuff to do all day, including eating chocolate and watching Netflix, so I kinda procrastinated the crap outta today, but I hope not to do this anymore in the future. Thank you for your attention and I'll see you in my next post! Stay safe everyone!