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Expanding, And Eventually Replacing, The International Space Station:
Aboard the International Space Station (ISS), humanity has managed to maintain an uninterrupted foothold in low Earth orbit for just shy of 20 years. There are people reading these words who have had the ISS orbiting overhead for their entire lives, the first generation born into a truly spacefaring civilization.
But as the saying goes, what goes up must eventually come down. The ISS is at too low of an altitude to remain in orbit indefinitely, and core modules of the structure are already operating years beyond their original design lifetimes. As difficult a decision as it might be for the countries involved, in the not too distant future the $150 billion orbiting outpost will have to be abandoned.
Naturally there's some debate as to how far off that day is. NASA officially plans to support the Station until at least 2024, and an extension to 2028 or 2030 is considered very likely. Political tensions have made it difficult to get a similar commitment out of the Russian space agency, Roscosmos, but its expected they'll continue crewing and maintaining their segment as long as NASA does the same. Afterwards, it's possible Roscosmos will attempt to salvage some of their modules from the ISS so they can be used on a future station.
(Score: 2) by Immerman on Wednesday March 04 2020, @05:10PM (2 children)
Air friction doesn't really have a delta-V, though I suppose you could calculate the delta-V loss per hour or year for a given orbit.
And really, there shouldn't be any technical issue with pushing the ISS to a higher orbit - other than that it makes it more expensive to get things too and from the station (basically, less payload per launch), and you'd probably want a weak rocket with a huge fuel tank slowly making the transition without risking over-stressing the sprawling space station that was never designed to take high thrust. That's a terribly fuel-inefficient prospect for a chemical rocket, but doable, especially with periodic refueling (which is a major unproven capability). It could be used as a reason to push development of a modust-thrust orbital "tug boat" designed to operate exclusively in orbit. (Perhaps built around a cluster of NASA NEXT ion thrusters powered by a NASA Kilopower reactors?)
The big question is, is it worth the effort? The ISS is basically a proof-of-concept station that's gradually grown over the last 20 years, with the primary mission really being to study the mental and physical health of the inhabitants. Technology has advanced a lot since it started, in a whole lot of different directions, and we're about ready to start building space stations that do something a lot more useful. If the ISS can't be readily upgraded in that direction, then it probably makes a lot more sense to scavenge the useful modules for a new space station, and dispose of the rest. Especially given that a lot of the core modules have now been operating considerably longer than they were originally designed for.
Not to mention the fact that our launch potential is poised to shortly return to payload capacities that we haven't had since the Saturn V last flew in 1973, long before anything on the ISS was launched. Basically, we're about to be able to launch much larger space station modules into orbit than anything on the ISS, far more cheaply than ever before (assuming the SpaceX Starship eventually succeeds). The ongoing value of the ISS itself is very much in doubt. I mean - consider that the passenger Starship is intended to have a greater pressurized volume in the cabin than the entire ISS combined, while likely having the payload capacity to launch the concept design Bigelow B2100 inflatable space station that provides twice that pressurized volume within a thick shell that provides ballistic and radiation defense designed to be superior to the walls of the ISS.
(Score: 2) by DannyB on Wednesday March 04 2020, @05:40PM (1 child)
I had gotten the idea in the 90s that the main purpose of ISS (unofficially) was to have a place for the Shuttle to go. Instead of doing endless circles around the earth.
And the purpose of continuing the expensive (reusable but at what cost) Shuttle was to service the ISS.
Nice, neat circular thinking. Managers like it and refer to it as: no loose ends.
Contractors like it because about four shuttle launches (I think) is roughly enough to buy another shuttle. [In Regan era, replacement shuttle $3 billion, cost of shuttle launch near program end approaching $1 billion; but I could be wrong esp. about the 2nd number]
The lower I set my standards the more accomplishments I have.
(Score: 0) by Anonymous Coward on Thursday March 05 2020, @12:21AM
You're pretty close to correct. Endeavour cost $2.2 billion, but that was mostly assembly, they already had most of the parts. It would probably have been somewhere in the $5-$10 billion range for a new orbiter from scratch, but they didn't need a huge fleet of shuttles, so the per unit cost isn't very important.
As for launch costs, that's about right. It cost about the same, inflation adjusted, to launch a Shuttle as it did to launch Apollo, even though it was much less capable and turned out to be not very reliable either.