# How feasible would it be to move the ISS to the surface of the Moon to recycle its components in future?

I see it as an awful waste of energy in not only creating the International Space Station (ISS) components, but also in getting them into space to only decommission the station by letting it fall back to Earth. Why not move the station either as a whole, or perhaps preferably in parts to the surface of the Moon, so that these materials and components are available to be recycled for future Lunar manned missions in order to help set up a Lunar base?

I would even go as far as saying that we should get one of the usable Space Shuttles back up into space and send it to the Moon to land there as well. All of these parts have been built to be space worthy, why not keep them out in space to be recycled later on? As I understand it, one of the most significant costs of space instruments is getting them into space and off the Earth's surface in the first place. Why waste the effort we have made in doing this already?

Wouldn't it be a great science experiment and learning experience in trying to move the station or its components to the Moon also? We have everything to gain by doing this.

• Funny part it would be probably easier to land it on Mars. – SF. Jan 23 '19 at 15:41

It wouldn't be at all. Let's look at it in a couple of different ways:

1. The delta v required is 5.93 km/s. That's not quite, but a similar level of difficulty as launching the station in the first place!
2. Landing either the Shuttle or the ISS on the moon would be difficult. They just weren't meant for it!
3. There might be some parts that are usable, but in large part, the end of life ISS is going to be because the parts are worn out.

Bottom line, it's not a whole lot cheaper to land on the Moon than it is to get to orbit in the first place, and there's questionable value of what would survive the process. Overall, it just isn't going to happen.

• Couldn't we just fit a large number of ion thrusters and gradually push the station to the moon? Im sure we could find a way to provide it with some kind of braking system to slow its descent to the moon surface. It wouldn't matter if some damage is incurred since we aren't aiming to use it as is but instead have it there as material to be used in the future. I do suspect though that some parts would remain somewhat usable or repairable so that It could act as an initial accommodation compartment for the lunar base engineers while working there. Even as extra shielding around inflatable module – user35276 Feb 6 '14 at 0:31
• @user35276 20, 000 tons of mass assembled from modules would take a good deal of braking even in Luna's reduced gravity. – Everyone Feb 6 '14 at 0:57
• @Everyone: the ISS weighs closer to 400 tons. – Hobbes Feb 6 '14 at 9:09
• Also mind: The ISS is constructed to be used in an environment without gravity. There is no space for beds, bu only floating sleeping bags. Storage lockers are all around. No paths to walk, no doors but smaller openings to float through etc. On moon there is gravity. So people wold walk (and hit their head on the "ceiling" when pushing a bit too hard) So only purpose could be for recycling some parts ... – johannes Jan 10 '18 at 20:28
• @LeoS it would certainly be something to see a Shuttle land itself canted and backwards though. – BMF Jan 12 at 12:20

The first part of getting ISS (or anything else) from LEO to the Moon is lifting it's orbit around the Earth (or at least one end of its orbit) until it reaches the Lagrange point between the Earth and the Moon (EML1). The delta-V requirements for this are on wikipedia. Using "high thrust" (a conventional rocket or similar doing all the work in a short period this needs about 3.77 km/s of delta-V. Using low thrust, like ion engines, about 7 km/s.

We can use the rocket equation

$${\displaystyle \Delta v=v_{\text{e}}\ln {\frac {m_{0}}{m_{f}}}}$$

to tell us how much propellant we'd need. For the high thrust option, using liquid hydrogen and liquid oxygen $$v_e$$ is abotut 4500 m/s and we get about 2.3 for the ration of the original mass to the mass delivered. So we'd need a bit over 500 tons of propellant to lift the ISS there. In this case the thrust would be high enough that we'd also have to worry about the ISS falling apart while we pushed it.

Using a xenon ion engine we have $$v_e$$ about 40 km/s, so the mass ratio needed is about 1.2 and we'd need 80 tons of Xenon, plus quite a lot of power generation and ion engines if we wanted the initial thrust to be enough to overcome air resistance. Apart from other problems, that is about 2 years world production of xenon and would cost about a hundred million dollars.

It may be possible to save a bit of delta-V by exploiting the interacting gravity of Earth, Sun and Moon, but it adds still more to the time taken.

Once we get to L1, it's easy, in a sense to get to the surface of the Moon. A small push in the right direction will do it. On the other hand it will get you there at about 2.5 km/s (about 5000 miles per hour) so there won't be a lot of usable components to recover from the new crater. Decelerating from that velocity can't be done with a low thrust system (you need enough thrust to hover on the Moon, which is about 700 kN for the ISS).

So you definitely need a chemical rocket engine for that final stage. Assuming you can somehow keep hydrogen liquid that long, you would need (rocket equation again) about 300 tons of propellant. On other words you need to deliver 700 tons of EML1, which then means that you needed about 900 tons of propellant (or 140 tons of Xenon) to get there from LEO.

So that's just the physics. From an engineering standpoint, most of the rockets and other systems that would be needed for this don't exist and would have to be designed, built and tested, before being launched to ISS. Which might be fun, but would be very expensive.

What might be feasible is simply to raise ISS's orbit to an alitutde where it would be stable for a few centuries, say 900km where the materials would be available just in case we want them for something.The Delta-V for that is about 300 m/s and could be achieved by something like a SpaceX starship with no cargo configured as a tug.

• Something I’d like to add regarding both comments - you also have to consider structural stability of the ISS, center of mass, center of thrust. The ISS is periodically reboosted into a higher orbit, so it could probably be done, but you’re going to have to be careful to ensure you don’t break the thing apart in the attempt. – Snoopy Jan 24 '19 at 3:18