Technical evaluation of destruction alternatives for the international space station.

In a document that accompanies the NASA announcement, it is explained how the unfortunate conclusion was reached that the best option is to destroy it and these are the alternatives that were considered before reaching that conclusion. First, the option of uncontrolled re-entry was considered. The atmosphere at 400 km altitude, which is where the station's orbit is, is very tenuous, but it is still enough to slow down the objects that are in orbit.

Being in orbit is basically going so fast that before falling back to Earth you turned around, but if there is something that slows you down, in this case the atmosphere you fall again, that's why the space station and all the objects that want to remain In orbit they have to use their thrusters and accelerate from time to time to stay up if the space station did not do this it would fall in 2 years.

The option of uncontrolled re-entry of the station would be to abandon it and let the drag of the atmosphere make it fall from its orbit to be destroyed by the heat generated when they fall from space, they burn when entering the atmosphere due to the friction of their components with the air due to its high speed.

The international space station weighs 420 tons, it is big enough for huge pieces of it and I mean tens or hundreds of tons of metal to survive re-entry and fall to the surface like tons of scrap metal and for that reason the option of uncontrolled re-entry was left. discarded.

Another option that was considered was to dismantle it in space and bring its parts back to Earth in vehicles. We do not need to know much about the aerospace issue to imagine that this would be very expensive and therefore this option is ruled out, but there are interested organizations. in preserving small parts of the station for their historical value such as the Smithsonian museum, the National Air and Space Museum and other organizations that are already coordinating this with NASA but on a small scale to bring artifacts, not complete modules, and make them part of their exhibits .

Another possibility was to propel the station to a higher orbit, where it would not be slowed down by the Earth's atmosphere so that it would remain there much longer despite being abandoned, in its current orbit at 420 km altitude if it were not accelerated from time to time. when to maintain its orbit the station would fall back to earth due to atmospheric drag in just 2 years and it would do so in an uncontrolled manner, which is what we want to avoid, but a higher orbit could last much longer as shown in this table below.

Raising its orbit just 200 km would increase its duration in orbit by 100 years before falling to Earth, that would be fine, it would remain intact as a kind of space relic, this possibility was ruled out because the higher the orbit, the more likely it is that the station is hit by other objects in orbit.

Currently, if there is a danger of encountering another object in orbit, the crew makes maneuvers to prevent it, lowering or raising the orbit a little to get away from the danger, but without a crew the station would not be able to evade dangerous objects and could be destroyed by watering an uncountable amount of dangerous objects in orbit.

This graph shows how the station without the ability to make evasive maneuvers at its current altitude would spend 51 years before being destroyed by a collision, but in a higher orbit, for example at 600 km, it would be destroyed in just 11 years and at 800 km it would be destroyed in 4 years, therefore that is not an option either and NASA decided on the last option, controlled re-entry.

NASA is already selecting SpaceX as the candidate to build an unmanned vehicle that will dock with the international space station and that will carry enough fuel to slow it down and make it fall back to earth, obviously they would remove the astronauts before doing so and the designated place For their remains to fall would be Point Nemo, a remote place in the middle of the Pacific far from any population on the seabed of that place rest the remains of many spacecraft including the MIR space station.

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