SpaceX builds vehicles. The Shuttle was “reusable” because they needed a term between the default for transportation capital expenditures (e.g. trains, planes, cars and ships) and the modified missiles that defined post-War spaceflight. “Reusable” in the Shuttle’s context meant months of specialist overhaul time and the cost of a Falcon 9 launch in SRB booster replacements alone [0].
At the end of the day, in 2010, “the incremental cost per flight of the Space Shuttle was $409 million, or $14,186 per kilogram” [1]. ($591mm and $20,512 in 2024 dollars, respectively [2].) SpaceX’s prices per kg are around $3,170 on Falcon 9 [3] and $1,520 for Falcon Heavy [4]. Starship should bring those costs below $1000.
It might, but it's also at a scale where people can dust off the old plans for orbital rings and ask if this time the economics work out.
(My guess is the economics are fine, but the politics would kill it on earth, so the moon or mars will get one, but that's just an interested amateur opinion).
Term of art for this is "design for demise", i.e. make everything of pieces small enough and materials ablative enough that there's less than 1 in 10k chance that any debris will survive to the surface.
IIRC, above something like geostationary they tend to decay upwards? Though the old orbital ring white paper wasn't suggesting anything like that, this was an alternative to needing to go so high in the first place.
(I may be misremembering or getting confused with a thing specific to tidal locking?)
That is indeed what you get with tidal forces - bodies closer than geostationary orbit lose angular momentum and decay inward, bodies further out steal angular momentum from Earth and move outward.
I suppose the same effect is there with satellites much smaller than the moon, but it would be tiny.
I wonder if they could have an orbit high enough to move away from earth with some kind of drag cables dangling from them into low orbit to counter the outward movement. Would that work?
These orbits have vastly different speeds though. Consider a high geosynchronous orbit vs. something like ISS which goes around the Earth in an hour or two.
but you are towing the cable and you'd only get so far down for the counteraction of force from gravity to pull on the cable. Would speed or friction on a cable be a problem.
Presuming it’s in LEO. When and if we ever get around to building these things they probably won’t be in LEO at least not for long. Some of them might not even be constructed from materials launched from Earth.
SpaceX builds vehicles. The Shuttle was “reusable” because they needed a term between the default for transportation capital expenditures (e.g. trains, planes, cars and ships) and the modified missiles that defined post-War spaceflight. “Reusable” in the Shuttle’s context meant months of specialist overhaul time and the cost of a Falcon 9 launch in SRB booster replacements alone [0].
At the end of the day, in 2010, “the incremental cost per flight of the Space Shuttle was $409 million, or $14,186 per kilogram” [1]. ($591mm and $20,512 in 2024 dollars, respectively [2].) SpaceX’s prices per kg are around $3,170 on Falcon 9 [3] and $1,520 for Falcon Heavy [4]. Starship should bring those costs below $1000.
[0] https://forum.nasaspaceflight.com/index.php?topic=51959.0
[1] https://en.m.wikipedia.org/wiki/Space_Shuttle_program
[2] https://www.usinflationcalculator.com/
[3] https://www.spacex.com/media/Capabilities&Services.pdf LEO
[4] https://en.m.wikipedia.org/wiki/Falcon_Heavy LEO, theoretical