STS assignments

The History of American Space Shuttles and STS Missions

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The American space shuttle (in English Space shuttle or Space Transportation System, STS) is a reusable spacecraft developed by NASA.

In 1977 “Entreprise” was the first shuttle to make test flights of a few minutes under the mission name “ALT-12,13,14,15 and 16”.

On April 12, 1981, the Shuttle Columbia will be the first to be part of a space mission lasting several hours, and will therefore be the first of a large series of missions under the name "STS".

Subsequently, no less than 135 STS missions will be launched, between 1981 and 2011 with different shuttles: “Challenger, Discovery, Atlantis, Endeavor and Columbia”.

How does the Space Shuttle work?

The space shuttle is made up of 3 distinct parts.

The Orbiter, or Shuttle, is the only component to be placed in orbit to transport equipment or astronauts during STS space missions.
The orange-colored external tank supplied the three SSME main engines with liquid hydrogen (the fuel) and liquid oxygen (the oxidizer) during the ascent of the ship.
The tank was divided into 3 parts, the liquid oxygen tank at the front, the liquid hydrogen tank at the rear and the "inter-tank" part between the two.
The only one of the 3 elements of the shuttle not to be reusable ended up being destroyed during its fall into the Earth's atmosphere.

The two solid boosters, in white, provide the additional thrust necessary for the shuttle in the first phase of its ascent.
The shuttle and the thrusters are the only reusable parts, indeed the shuttle after its re-entry into the Earth's atmosphere comes to land like an airplane on one of the landing strips provided for this purpose, at the Kennedy Space Center or at the air base Edwards.
As for the propellants, they are recovered by two boats after they have fallen into the sea, the Liberty Star and the Freedom Star. Two unique vessels specially built by NASA for these operations.


The different missions of the STS shuttles

During the 34 years of STS missions, the shuttles have taken part in various missions, such as the construction, refueling, and supply of the International Space Station which is still in operation.
At the launch of several communication satellites, space probes and military satellites.

But also to put the Spacelab laboratory into orbit to carry out microgravity experiments or operate instruments in a vacuum.
And Spacehab which serves both as a space laboratory, but also allows the chartering of equipment to the International Space Station.

On April 24, 1990, the Hubble telescope was sent during the STS-31 mission aboard the discovery shuttle.

putting the hubble telescope into orbit

The Tragic History of STS Missions

Space exploration is not easy, like all explorers through time the possibility of a tragic end is always considered.

The STS-7 mission in 1986 was the first drama of the STS missions.
During the take-off of the Challenger space shuttle, the rupture of one of the O-rings of one of the two solid rocket boosters attached to the main hydrogen tank allowed a flame to pass towards the external tank. 72 seconds after the launch, the external tank exploded and destabilized the other booster which came to touch the head of the rocket, which exploded in turn.

Shuttle Challenger was not destroyed at the time of the explosion. After disintegration due to aerodynamic forces, the tank ignited within seconds, forming a huge ball of fire.
The cabin containing the 7 passengers of the shuttle began a free fall of two minutes in the direction of the ocean.

NASA engineers found that the astronauts survived the initial shock, with an emergency oxygen cylinder activated shortly after.
Currently, we still do not know if it is the free fall in the depressurized cabin or the impact with the ocean that is responsible for the death of the astronauts.

A few years later, it was the turn of the STS-107 mission to turn into a disaster.
During the takeoff of the space shuttle Columbia, a piece of insulating foam detached from the external tank, hitting the left wing of the space shuttle, which damaged the thermal shield (Thermal Protection System (TPS)) which is used to protect the shuttle from the heat generated during re-entry into the Earth's atmosphere.

The shuttle was traveling at Mach 2.46, or 2,523 km/h. Arrived at an altitude of about 20,000 m, the sheet of foam came off.
Slowed down by air friction, it struck the leading edge of the shuttle's wing at a relative speed of around 877 km/h.

Unfortunately too confident in the solidity of the material constituting the leading edge, the NASA engineers considered this hitch as benign, they indicated to the astronauts that they could continue their mission without problem.
It was at the time of the return, and the entry into the atmosphere, that the drama happened.

The hot gases produced during the atmospheric re-entry entered the wing through the hole left during the previous impact, and quickly reached its internal structure, which caused the disintegration of the vessel.


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