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This plan is an insane waste. Other than Zarya and the other Russian built modules, the American, Japanese, and European ISS segments have held up quite well.

This plan is an insane waste. Other than Zarya and the other Russian built modules, the American, Japanese, and European ISS segments have held up quite well. Despite the intense thermal cycles and stress, these modules continue to operate with some repairs to sub-systems along the way. For example, Tranquility's Carbon Dioxide Removal Assemblies (CDRAs) has had two unrelated failures a decade ago (2013), but they've been repaired and the station continues to function. And it should function for at least another two decades. We've spent so much money trucking these segments up the gravity well, and large parts of the structure are "fine," for an unknown quantity of fine. The primary structure, the Integrated Truss System https://en.wikipedia.org/wiki/Integrated_Truss_Structure https://en.wikipedia.org/wiki/Integrated_Truss_Structure, has been monitored constantly and hasn't experienced any significant degradation (or, degradation that has been made public). The modules may not be fresh off the assembly line, but they should continue to function. My analysis is limited by the fact that I haven't been able to find a technical assessment of the central truss' lifetime, but currently there is no reason why it shouldn't continue to function far into the future as new modules are swapped in and out. The Truss itself is modular, and if push comes to shove, it is cheaper to start replacing segments than it is to build a new station Here is a simple proposal. We should send up thermal blankets, more radiators, and a better thermal management system to reduce thermal stress on the station via expansion & contraction. We should also develop secondary systems for each of the major sub-components that are nearing the end of life, and perform 1-to-1 swaps with existing systems (this has been done before!) We should then boost the perigee up to at least 1,000km. As the density dropoff is exponential, the ISS will then last in this orbit for several hundred years. The ISS should then be privatized (but managed by the USG + ESA), with different trusses, spaces being allocated to allow people to build on top of the ISS' infrastructure and experiment with in-orbit construction, manufacturing, and mass chemical synthesis in orbit for pharmaceuticals.

ericcumbee 3y ago
the problem is I don't think there is interest in privatizing the station. I think it was floated at one point, but Axiom and Blue Origin seem to be more interested in building their own stations. especially when the prospect of being able to launch the entire orbital mass of the ISS on two expendable Super Heavy/Starship rockets is on the horizon. also I don't know how hard it is to change the stations orbit inclination, but when they went from being Space Station Freedom to the ISS the orbit was changed to allow the Russians to be able to launch to it. That drastically reduced the amount the Shuttle could carry to the ISS. From my understanding Axiom and Blue Origin are both planning to optimize for launch from North America.
- deleted 3y ago
  [deleted]
throwawaymaths 3y ago
(only half joking) but how bad does it smell in those segments after decades of canned recycled air?
- dotancohen 3y ago
  > how bad does it smell in those segments Depends
ericbarrett 3y ago
> We should then boost the perigee up to at least 1,000km. This would expose the occupants to significantly more radiation, would it not? The Van Allen belts start at ~650 km, varying with latitude and solar weather.
- areoform 3y ago
  You're absolutely right! The inner belt starts at, > The inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii (L values of 1.2 to 3) or 1,000 km (620 mi) to 12,000 km (7,500 mi) above the Earth.[3][13] In certain cases, when solar activity is stronger or in geographical areas such as the South Atlantic Anomaly, the inner boundary may decline to roughly 200 km[14] above the Earth's surface. I found a graph that shows the dose rates at given altitudes for circular orbits, https://ars.els-cdn.com/content/image/3-s2.0-B9780128140581000035-gr005.gif https://ars.els-cdn.com/content/image/3-s2.0-B97801281405810... You quickly get into the centuries range as you approach a 800km perigee, see, https://www.researchgate.net/figure/Orbital-decay-of-the-spacecraft-in-LEO-vs-initial-orbital-altitude-with-respect-to-the_fig15_268373551 https://www.researchgate.net/figure/Orbital-decay-of-the-spa... With the ISS' large cross section, it will experience more drag, but (and this is a guess) the reboost time would be measured in years and decades rather than months somewhere between 750km to 800km. Maybe there's an altitude here that's safe and doesn't poison humans? I also found a report of shielding required for given equatorial circular orbits at different altitudes, https://space.nss.org/wp-content/uploads/Orbital-Space-Settlement-Radiation-Shielding-Globus.pdf https://space.nss.org/wp-content/uploads/Orbital-Space-Settl... > Table 4 suggests that for settlements in low equatorial orbit (below 500 km), no shielding mass is required to meet the 20 mSv/year and only a tiny (equivalent to polyethylene 0.01 ton/m2) amount to meet the 6.6 mGy/year limit. The ISS has an average of about the equivalent of 200 kg/m2 aluminum shielding [Cucinotta 2013]. Thus the minimal shielding provided by a pressure hull, solar arrays, whipple shield, etc. should be sufficient to meet the pregnant woman threshold. This has radical implications for space settlement as discussed below. > There is a very high radiation level (mGy/year column) with no shielding at 600 km. This is mostly trapped protons that can be easily shielded as is seen from the rapid dropoff when small amounts of shielding are added. Increased inclination (such as the ISS' orbit), means increased radiation exposure as they pass through the south atlantic anomaly.
Tuna-Fish 3y ago
ISS requires too much constant maintenance. No-one would be willing to operate it at what it costs NASA. Any future space stations want to learn from the lessons of ISS and build something that doesn't require constant work and monitoring to function, and with modern launch prices you can get the baseline capability up there for just a few years of ISS maintenance.

ericcumbee 3y ago

the problem is I don't think there is interest in privatizing the station. I think it was floated at one point, but Axiom and Blue Origin seem to be more interested in building their own stations. especially when the prospect of being able to launch the entire orbital mass of the ISS on two expendable Super Heavy/Starship rockets is on the horizon. also I don't know how hard it is to change the stations orbit inclination, but when they went from being Space Station Freedom to the ISS the orbit was changed to allow the Russians to be able to launch to it. That drastically reduced the amount the Shuttle could carry to the ISS. From my understanding Axiom and Blue Origin are both planning to optimize for launch from North America.

deleted 3y ago
[deleted]

throwawaymaths 3y ago

(only half joking) but how bad does it smell in those segments after decades of canned recycled air?

dotancohen 3y ago
> how bad does it smell in those segments Depends

ericbarrett 3y ago

> We should then boost the perigee up to at least 1,000km. This would expose the occupants to significantly more radiation, would it not? The Van Allen belts start at ~650 km, varying with latitude and solar weather.

areoform 3y ago
You're absolutely right! The inner belt starts at, > The inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii (L values of 1.2 to 3) or 1,000 km (620 mi) to 12,000 km (7,500 mi) above the Earth.[3][13] In certain cases, when solar activity is stronger or in geographical areas such as the South Atlantic Anomaly, the inner boundary may decline to roughly 200 km[14] above the Earth's surface. I found a graph that shows the dose rates at given altitudes for circular orbits, https://ars.els-cdn.com/content/image/3-s2.0-B9780128140581000035-gr005.gif https://ars.els-cdn.com/content/image/3-s2.0-B97801281405810... You quickly get into the centuries range as you approach a 800km perigee, see, https://www.researchgate.net/figure/Orbital-decay-of-the-spacecraft-in-LEO-vs-initial-orbital-altitude-with-respect-to-the_fig15_268373551 https://www.researchgate.net/figure/Orbital-decay-of-the-spa... With the ISS' large cross section, it will experience more drag, but (and this is a guess) the reboost time would be measured in years and decades rather than months somewhere between 750km to 800km. Maybe there's an altitude here that's safe and doesn't poison humans? I also found a report of shielding required for given equatorial circular orbits at different altitudes, https://space.nss.org/wp-content/uploads/Orbital-Space-Settlement-Radiation-Shielding-Globus.pdf https://space.nss.org/wp-content/uploads/Orbital-Space-Settl... > Table 4 suggests that for settlements in low equatorial orbit (below 500 km), no shielding mass is required to meet the 20 mSv/year and only a tiny (equivalent to polyethylene 0.01 ton/m2) amount to meet the 6.6 mGy/year limit. The ISS has an average of about the equivalent of 200 kg/m2 aluminum shielding [Cucinotta 2013]. Thus the minimal shielding provided by a pressure hull, solar arrays, whipple shield, etc. should be sufficient to meet the pregnant woman threshold. This has radical implications for space settlement as discussed below. > There is a very high radiation level (mGy/year column) with no shielding at 600 km. This is mostly trapped protons that can be easily shielded as is seen from the rapid dropoff when small amounts of shielding are added. Increased inclination (such as the ISS' orbit), means increased radiation exposure as they pass through the south atlantic anomaly.

Tuna-Fish 3y ago

ISS requires too much constant maintenance. No-one would be willing to operate it at what it costs NASA. Any future space stations want to learn from the lessons of ISS and build something that doesn't require constant work and monitoring to function, and with modern launch prices you can get the baseline capability up there for just a few years of ISS maintenance.