[jonahhorowitz]

I understand that we have to deorbit the ISS at some point, but it's crazy to me that it's cheaper to deorbit all this debris rather than recycle some of it. It's already in orbit. There are "giant steel trusses" - wouldn't it be easier to make the next space station out of some of the existing space station?

[icegreentea2]

FYI, here's a NASA page about ISS transition: https://www.nasa.gov/faqs-the-international-space-station-tr...

Quick summary (avoiding duplicating points other posters have already made):

* NASA's current plan for post ISS operations is to not be in the LEO space station business. NASA wants to buy LEO manned services if required from commercial operators (the same way NASA has left the business of delivering cargo and humans to the ISS). NASA will focus manned operations effort on beyond LEO.

* NASA has submitted an RFI asking for commercial interesting in re-suing major components of the ISS and says that it received no viable submissions.

[troupo]

> for commercial interesting in re-suing major components of the ISS and says that it received no viable submissions.

Of course the haven't received any viable submissions. Pretty much anything space-related are one-off specialized extremely costly components not used anywhere else. And there's like two people knowing how to build them, and they are already employed by NASA

[thombat]

Anything launched is assembled from parts that have been certified as fit for purpose, voluminous paperwork showing the examinations, testing, etc, all to try to minimise the risk of failure. Once it has been in orbit for years or decades, facing ten thermal cycles per day, bathed in elevated radiation and ions, and pitted with micrometeorites, you'd really want a thorough examination before reuse (X-ray ultrasound, etc: not yet available off-world)

[s1artibartfast]

It would be far harder and more expensive to reuse parts.

Just because there are mechanical parts and doesn't mean that they are reusable or serviceable.

Humans have basically no ability to do any manufacturing construction or service in space. It takes an 8 Hour Eva to change a couple bolts, risking human life all the time.

Bringing all of the tools and equipment to space to facilitate reuse would require far more than simply replacing it.

On top of that, most of the space station is worn out and far beyond it's design lifetime.

[ge96]

Space robot workers... How far away

[thombat]

Further away than non-space robot workers, and we don't really have those either (at least not in the sense of machines operating autonomously in arbitrarily complex environments such that humans aren't required at all)

[Tommstein]

And consider that the Space Shuttle was used extensively late in its life to help build the ISS. We have nothing similar to help build another one. I'm sure there's good reasons to do it (hopefully not just budgetary ones), but it's unfortunate that we're deorbiting it at all. The cost of maintaining/upgrading the one we already have probably pales in comparison to the cost of ever building another one.

[8bitsrule]

Lot of useful mass there. Recycling makes a lot of sense, and we will wind up sorry if it's not done. Wouldn't take much to put it up into a very high parking orbit.

[s1artibartfast]

What would it take to put it in a parking orbit?

[philipwhiuk]

A lot of delta-V.

The only parking orbit is graveyard, above GEO - everything decays over a fairly short time period.

[oldbbsnickname]

Yep. It would require a ton of money to tank that much fuel up there. For maintenance alone, ISS requires 7 metric tonnes of fuel every year just to stay where it's at.

[wkat4242]

7 metric tonnes isn't a lot. It's what a 747 uses to taxi to the runway.

Of course bringing 7 tonnes to orbit is another story but even that is not so bad.

[Plasmoid]

If there was more industry in space, it would make some sense. The problem now is there isn't enough demand for it, and if you don't maintain the orbit for this stuff, it'll cause problems. The most likely problem is that it'll do a uncontrolled re-entry somewhere on Earth and hit someone. The other possibility is it'll wander in its orbit and smash into something else in orbit.

Also, if it's not big enough to monitor it can disappear. Radar makes it hard to track anything that's not huge and actively transmitting.

[Tommstein]

> Also, if it's not big enough to monitor it can disappear. Radar makes it hard to track anything that's not huge and actively transmitting.

I don't know about that:

"Since 1990, the Goldstone Orbital Debris Radar has collected orbital debris data for debris as small as about 2 mm in LEO for the NASA ODPO. . . . . The Goldstone Orbital Debris Radar is an extremely sensitive sensor capable of detecting a 3-mm metallic sphere at 1000 km, which makes it an incredibly useful tool in the characterization of the sub-centimeter-sized debris population." - https://orbitaldebris.jsc.nasa.gov/measurements/radar.html

[bagels]

Mechanical parabolic dish is severely limited in the number of objects that can be tracked per unit of time. The object has to pass through the narrow beam.

There's a trade-off between sensitivity and number of objects you can track, and mechanical steering is inferior to phased arrays for rapidly changing targets.

[kevin_thibedeau]

The US will never build another station at the inclination of the ISS. That was solely a concession to satisfy Russia so they could be a partner. Moving that equipment to another orbit isn't economically feasible.

[dabluecaboose]

For context, inclination change maneuvers are often the most expensive type of maneuever, even topping launch from the surface to LEO depending on the altitude and amount of inclination changed.

https://en.wikipedia.org/wiki/Orbital_inclination_change#Cir...

(The circular orbit inclination change is sufficiently simplified for a back-of-the-napkin comparison.)

[ralfd]

Some have the same idea:

https://spacenews.com/industry-sees-missed-opportunity-in-de...

> Industry sees missed opportunity in deorbiting ISS

> “As technology matures, certainly in the next decade we’re going to get to the point where we’re going to be able to reuse and recycle a lot of these materials,” said Ron Lopez, president and managing director of Astroscale U.S., a company working on satellite servicing and debris removal technologies. “Instead of letting it burn up and lose all of that economic value, you take it to a foundry in space” and break it down into raw materials, he said during a Satellite 2023 panel March 16.

Easier said than done though.

There is also the question if the ISS, despite construction costs of hundred billion dollars, is really much worth in a decade. When Starship is flying you could use a modified rocket itself as a space station:

https://arstechnica.com/space/2023/07/could-spacex-turn-star...

[nradov]

Why would anyone launch a foundry into the same orbit as the ISS? Seems pointless.

[ChuckMcM]

If we have on-orbit refueling and Starship on or before 2031, it would be possible to "park" the ISS at the Earth/Lunar L4 or L5 Lagrange points. Conversely it could be parked in a solar orbit far enough out to not interfere with geosynchronous satellites but close enough that a small tug to move it up or down to maintain spacing with the Earth.

Given its mass, either option would require significant delta-v to get it parked. The L4 and L5 points have the advantage that it could pretty much live there without worrying about station keeping.

I expect its possible to do it with a series of Falcon 9 launches of several tug craft but the co-ordination of that would be very difficult to pull off.

[duskwuff]

> If we have on-orbit refueling and Starship on or before 2031, it would be possible to "park" the ISS at the Earth/Lunar L4 or L5 Lagrange points.

Absolutely not; that's absurd. The current orbit of the ISS is roughly 400 km. L4 and L5 are roughly the same distance as the moon, at ~384,000 km, and in a different orbital plane.

[ChuckMcM]

From published data[1]:

Starship can carry 1200t of propellant. Starship has three Raptor 2 Vacuum engines, each with about 3.5km/s of delta-V ISS has an orbital velocity of 7.66km/s , escape velocity is 11.2 km/s. ISS weighs 400 tons.

There are unknowns, how much acceleration can the ISS support without falling apart. Since this is a two step process (change the orbital plane and change the orbital altitude) one will have to plan for avoiding other things in similar orbits. Finally, while I suspect a fully fueled Starship could do this with one tank, if you need to refuel between steps it would be more efficient to change the orbital plane, refuel and then change the orbit.

Putting it into an Earth/Sun concentric orbit might be easier.

[1]: Yes, its all wikipedia and such and no I haven't built a Kerbal model and run it, and yes it would be a "stunt" but penciling it out with some fellow space nerds the numbers aren't "ridiculous." But it absolutely does require the ability to fill up the tanks (maybe more than once) while on orbit.

[s1artibartfast]

My napkin math using typical delta-v.

Standard LEO to earth-Lunar L4/5 is a delta V of ~4km/s at high thrust or ~8km/s at low thrust. [1]

You can use the Tsiolkovsky rocket equation to calculate how much fuel you need to move the space station. [2]

(Station +fuel mass)/(Station mass) = e^(deltaV/engineISP*gravity)

ISP for an efficient rocket engine like raptor in vacuum is 360 s, you get a ratio of 9.7. If (Station +fuel mass)/(Station mass) = 9.7 so fuel required = 8.7x the station mass.

The space station is 420,000 kg, so we need 3,650,000 kg of fuel. Falcon 9 payload to LEO is 22,000 kg, so this is 167 Falcon 9 cargo launches.

Starships hypothetical cargo is 120,000kg to LEO, so 30 starship launches would be required just for fuel to move the space station.

Some starships would have to act as engines and fuel tanks for the space station, further increasing the mass and number of launches. Starship fuel capacity is 1,200,000 kg and the empty mass is 100,000kg, so you would need at least 3 starships as tanks, which adds another 300,000kg of mass to move.

https://en.wikipedia.org/wiki/Delta-v_budget#Earth%E2%80%93M...

https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

https://www.spacex.com/vehicles/falcon-9/

[duskwuff]

Not to mention: even if it were possible to move the ISS to L4/5, and get it there in one piece... why? We don't have the infrastructure to keep the station supplied, and it's likely to overheat badly (since it's no longer in Earth's shadow half of the time). It's a lot of effort with no clear payoff.

[stoneman24]

Isn’t the ISS inside the van Allen belts and protected( to some degree) from radiation. Moving up to a much higher orbit would increase the amount of radiation that hits it. It would need more shielding (or better radiation shelters) if you are still going to use it as an occupied station. Not able to research the details just now.

With hopefully the much better launch capability of starship, a new station is probably the best way forward.

[ChuckMcM]

Yes, I think moving it would only be to preserve it as an artifact, it would not be usable parked up there. And yes, a new station is planned AFAICT.

[gregoriol]

We don't even re-use parts on cars, which should be many times easier to re-use than parts on the space station

[ralfd]

But we do?

https://www.autocar.co.uk/car-news/consumer/thieves-strippin...

[gregoriol]

To use on the same model, not to use on a new generation