So I’ve just heard they’ve set a year of 2032 to decommission the International Space Station. Since if they just left it, its orbit would eventually decay and it would crash. Rather than have a million tons of metal crash somewhere random, they’ll control the reentry and crash it into the spacecraft graveyard in the pacific.
But why not push it out of orbit into space? Given that they’ll not be able to retrieve the station in the pacific for research, why not send it out into space where you don’t need to do calculations to get it to the right place.
In: Planetary Science
I think the misconception here is that an orbit is something you can be easily pushed out of. In truth, an orbit is a state of perpetual falling while missing the ground, so no matter how you push or pull, you can just fall differently. So the proposal now is to fall in a controlled manner so that it can be calculated where and when it will hit the ground.
In order to make the ISS leave the Earth’s orbit and go venturing out into space forever, it would take immense amounts of fuel and possibly the installation of real propulsion systems in the first place. That’s much more expensive and complicated than just dropping it.
It would take a *lot* of energy to make ISS escape Earth. Like, an amount comparable to the energy to orbit the thing in the first place, which was dozens of rocket launches. Making it re-enter in a controlled manner takes almost nothing, just the decision to do so. It is so low (skimming the upper atmosphere all the time) that just doing nothing to it for about 6-8 months would make it re-enter and burn up.
Leaving orbit is a loooooot harder than you think. Gravity is strong, man. You can’t just fling the ISS out into space with a few nudges from boosters, no, you would need to strap on enormous engines like the kind used to go to the moon.
Imagine a piano sitting halfway up a flight of stairs, right on the edge of a step, and you don’t want it on the stairs anymore.
Pushing it out down the stairs is like a controlled reentry in the ocean. You still need to expend energy to do this, but it’s not that hard.
Moving it to the top of the staircase is like pushing it to a higher orbit. Technically possible, but much more difficult and you’d need to use some tools/pulleys/etc (e.g. propulsion) you don’t currently have.
Edit: helpful addition from Borgnasse below: the piano is only on the first step of a very tall staircase
To go downwards you need some fuel until the drag of the atmosphere takes over.
To push it upwards you’d need A LOT of fuel since you never get any assistance. It’s also a massive structure that was assembled in multiple rocket launches, so by its very nature it will be expensive to move with rockets alone.
A common misconception is that you can just drive towards a certain direction in space since there’s no friction. In reality, the way of going to a higher orbit is accelerating sideways and in this case, a safe orbit would be pretty high and therefore very expensive.
There was actually this idea to put the ISS in a “parking” orbit at a much much higher altitude than it currently sits. Given how large and heavy the ISS is though in conjunction with not having a true propulsion system the cost would be astronomical (no pun intended). This would basically make it a “space museum” for later generations. At the end of the day though NASA has a finite budget and need to make the best decisions they can with what they have.
The ISS orbits at around 7.5km/s. The earths escape velocity is 11.2 km/s. We would need to increase the ISS speed by about 50% to launch it into space, which would take massive engines burning a massive amount of propellant
To add onto what others have written, something like this is done for satellites on the geostationary orbit, which is too far out for a quick, cheap (fuel-wise) deorbiting. What geostationary satellites do instead is to increase their orbit somewhat so that they no longer take valuable space on the geostationary orbit. This is called a graveyard orbit. It’s far out so it doesn’t matter that there are uncontrollable satellites or space debris.
But this is impractical for the ISS. The ISS is massive, and any changes of velocity require a lot of fuel. It is also quite low near Earth, so getting it far enough where it cannot bump into other satellites would require huge amounts of fuel.
Note that even graveyard orbits are still well below the velocities required for leaving Earth’s gravitational influence completely.
Aside from the feasibility of pushing it into space. It’s a bit irresponsible. At some point it is going to hit something. Very low chance that it matters. But still. Return the cart to the corral.
People are missing a couple of points here.
a) It doesn’t actually need to escape Earth orbit to end up in a stable orbit that wouldn’t naturally decay for hundreds, thousands, or millions of years. We can just put it in a sort of high ‘museum’ orbit and it could remain there long enough for, theoretically, some spacefaring racoon people to find it in 30 million years.
b) It’s simply not going to collide with anything up there, especially if we push it beyond what are considered the more useful orbits, and make sure it’s at an angle to the equatorial plane.
c) It already has a reusable rocket motor that could achieve this, it would ‘only’ need the fuel (only is in quotes because it’d be a decent amount of fuel).
The reason we’re not doing it is because getting the necessary fuel up to it would cost millions (not prohibitively expensive these days, but still it’s a cost with no easily arguable benefit), and because people in general simply don’t have that same kind of sentimental urge to preserve cool things.
If it were up to me, I’d push it into orbit around the Moon and give it a new berth for reusable taxis to and from the lunar surface. Then trips to the Moon would just rendezvous with the ISS first, they’d only need to bring fuel for their chosen lunar lander. (But then again, maybe a whole new station would simply work out cheaper and better. I’m sure they’ve considered this as well.)
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