The history of space shuttles and STS missions
The Space shuttle or Space Transportation System (STS) is a reusable spacecraft developed by the NASA.
In 1977, ‘Enterprise’ is the first shuttle to make test flights of a few minutes, known as missions ‘ALT-12, 13, 14, 15 and 16’.
On April 12, 1981, the shuttle Columbia will be the first one to be part of a space mission lasting several hours, and will be thus the first of many missions carried out under the name ‘STS’.
Later, as many as 135 STS missions will be launched between 1981 and 2011, using different shuttles: ‘Challenger, Discovery, Atlantis, Endeavour and Columbia’.
How does the Space Shuttle work?
The Space Shuttle is made of 3 distinctive parts.
The Orbiter, or Shuttle, was the only part sent into orbit to carry cargo or the astronauts during STS missions.
The orange external tank fuelled the three main SSME engines in liquid hydrogen (the combustible) and liquid oxygen (the combustive) during the take-off of the spaceship.
The tank was divided in 3 parts, the liquid oxygen tank at the front, the liquid hydrogen tank at the back, and the ‘inter-tank’ section between both.
The one of the 3 elements which was not reusable ended up disintegrated in the Earth’s atmosphere.
The two solid rocket boosters, in white, bring the extra thrust essential for the shuttle in its initial ascent phase.
The shuttle and the solid rocket boosters are the only reusable parts, indeed after entering the Earth’s atmosphere, the shuttle lands like a plane on one of the runways intended for that purpose, at the Kennedy Space Center, or at the Edwards Air Force Base.
As for the solid rocket boosters, after they fall into the sea, they are recovered by two ships, the Liberty Star and the Freedom Star. Two unique vessels specially built by the NASA for these operations.
The different missions of the STS shuttles
In the course of the 34 years during which STS missions were carried out, the shuttles took part to different missions, such as the construction, the supply and provision of the International Space Station, still in operation today.
The shuttles took part to the launch of several communications satellite, space probes and military satellites,
but also contributed to putting into orbit the Spacelab conducting experiences of microgravity and testing instruments in a vacuum.
It helped put into orbit the Spacehab, a space laboratory which also allows to transport cargo to the International Space Station.
On April 24, 1990, the Hubble Space Telescope was launched into space on board the Space Shuttle Discovery as part of the STS-31 mission.
The tragic story of the STS missions
Space exploration is a rocky road. As with every exploration which has been carried out through time, the possibility of a tragic end is always contemplated.
The STS-7 mission in 1986 was the first drama of the STS missions.
At the lift-off of the Space Shuttle Challenger, due to a breach in one of the O-rings of one of the two rocket solid boosters, located next to the main hydrogen tank, a flame was able to reach the external tank. 72 seconds after the launch, the external tank exploded and unsettled the other booster, which hit the head of the rocket, leading to the explosion of the latter as well.
The shuttle Challenger was not destroyed at the time of the explosion. After it disintegrated due to the aerodynamic forces, the tank burst into flames, forming a huge ball of fire.
The crew compartment with the 7 passengers of the shuttle started a free fall of two minutes towards the ocean.
The engineers of the NASA discovered that the astronauts had survived the initial impact, as an emergency oxygen tank had been activated right after.
As of today, we still do not know if it is the free fall in the depressurised cabin or the impact with the ocean which led to the death of the astronauts.
A few years later, it was the STS-107 mission which took a disastrous turn.
At the lift-off of the shuttle Columbia, a piece of insulating foam fell from the external tank and hit the spacecraft left wing. It damaged the Thermal Protection System (TPS) which protected the shuttle from the heat generated during atmospheric re-entry.
The shuttle was moving at Mach 2.46, that is 2,523 km/h. At an altitude of around 20,000 m, the piece of foam came off.
Slowed down by air friction, it hit the wing leading edge of the shuttle at a relative speed of 877 km/h.
Unfortunately, too confident in the solidity of the material used for the leading edge, the engineers of the NASA considered this as a minor incident and told the astronauts that they could safely go on with their mission.
Upon returning to Earth, that is when the tragedy happened, while the shuttle was re-entering the atmosphere.
The hot gas generated during the atmospheric re-entry penetrated the wing through the hole left by the previous impact and quickly reached the internal structure, which led to the disintegration of the spacecraft.