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Materials aging in space is a pretty deep subject. That it is the Russian Zvevda module that is leaking/cracking is likely related to the fact that it is also t
by ChuckMcM 6y ago
Materials aging in space is a pretty deep subject. That it is the Russian Zvevda module that is leaking/cracking is likely related to the fact that it is also the oldest module in the ISS.
The ISS is/was scheduled to be retired in 2024 (aka 3 years from now) but there are calls to keep it going. My fantasy would be to have SpaceX move it into the Lunar L1 Lagrange point which would keep it in use but it would have to deal with more cosmic rays, also station keeping would be an issue unless we could really get energized tether station keeping to work (lots of solar energy to provide power, but not a lot of mass to provide thrust, so tethers are energized conductors that push against the Earth's magnetic field)
Parking it in L4 or L5 could keep it for future generations but it would be even more of a challenge to go visit.
- jeffcox 6y agoI realize their orbit is relatively clear of debris and micro meteors, but is this materials decomposing or degrading and not random damage and happenstance? The ISS has no doubt been important and I remember how excited I was when it was being assembled. Is it really so historically significant it's worth the amount of effort you're describing?
- thescriptkiddie 6y agoCracks are a common sign of metal fatigue, which can be caused by repeated stress cycles. Imagine bending a piece of plastic back and forth until it snaps.
- pengaru 6y agoEspecially for "cold butter" metals like aluminum and copper.
- ben_w 6y agoI’ve never heard that phrase used in this content before. How does “cold butter” apply to these metals?
- fao_ 6y agoI think it refers to the type of break the joint makes? However, while searching I found this search excerpt: Which metals diffuse into other metals and how? | Naked ... www.thenakedscientists.com › forum Sodium and potassium metal (both *soft solids, like cold butter*) react So perhaps it is used to designate 'soft solids' versus 'hard solids'
- pengaru 6y agoI don't recall which of the many print books I read in my gearhead/TIG-welding days had used the term, but the lack of a distinct fatigue/endurance limit [0] for these metals was put into practical terms with something along the lines of "like slightly bending a cold stick of butter". It's why aluminum airplanes are supposed to get inspected for cracks regularly, and why aluminum bicycle frames must be so uncomfortably rigid. If there's cyclic stress occurring, it's a question of when, not if they will crack. If I had to guess it's from Carroll Smith's 80s-era Engineer to Win, it sounds like something he'd write. [0] https://en.wikipedia.org/wiki/File:S-N_curves.PNG https://en.wikipedia.org/wiki/File:S-N_curves.PNG
- lmilcin 6y agoHull is definitely not decomposing or degrading. If left in peace at sufficiently high altitude it would look the same in a million years. My bet is the issue is most likely stresses due to vibrations under pressure and pressure changes. It is complex but also well known problem. As the astro/kosmonauts move about the station, resupply dock, pressure changes, etc. some parts are being subject to constantly changing stresses while already being stressed due to pressure. It might also be possible that there are some additional thermal stresses but I think it is less likely these are source of the problem.
- Voloskaya 6y ago> My bet is the issue is most likely stresses due to vibrations under pressure and pressure changes. So you are saying it's degrading?
- maxerickson 6y agoThese discussions about materials are often difficult, because there are meaningfully different processes that are lumped together in everyday language. Mechanical stresses leading to failure at a particular point are certainly a form of degradation, but I believe they mean degradation in the sense where the entire body of the material is undergoing some change (like a plastic bottle fogging or such). I think seeking clear descriptions is fine, treating it as a "gotcha" game is tedious and unnecessary.
- lmilcin 6y agoI took liberty to look through the literature and it seems change of physical and chemical properties of material due to all types conditions (including physical stresses) is covered by the term. I am not into mechanical science that much, I have always treated degradation as a kind of surface or volume phenomena where the material looses its properties due to temperature, radiation, age, chemical reaction, etc. For mechanical effects there are already very good terms like metal fatigue and stress induced cracking.
- waheoo 6y ago
- elihu 6y ago> Is it really so historically significant it's worth the amount of effort you're describing? Space launches are getting a lot cheaper, so moving the ISS to another orbit might not be such a big deal as it used to be. We don't really need to keep the ISS around forever, but on the other hand, losing it would in some ways be similar to the burning of Notre Dame in 2019 (I can't believe that was less than two years ago). It's mankind's first permanent foothold in space. In that sense, it's irreplaceable. Let's say moving the ISS at the end of its usable lifespan costs a half billion dollars. That's like asking every U.S. taxpayer to pay about two dollars. Is it worth it? To me I think it's worth a lot more than two dollars, even if it unlikely that i'll ever actually be able to visit the ISS in my lifetime.
- jarofgreen 6y ago> It's mankind's first permanent foothold in space. Mir?
- elihu 6y agoGood point, I forgot about Mir. According to wikipedia it lasted from 1986 to 2001. I had briefly considered Skylab, but figured it didn't really count as "permanent". Wikipedia says it was up for 24 weeks.
- unixhero 6y agoI loooove Lagrange points
- akiselev 6y ago> That it is the Russian Zvevda module that is leaking/cracking is likely related to the fact that it is also the oldest module in the ISS. Definitely sounds like it. They can't identify the leak on the inside so it doesn't sound like a micrometeoroid impact and they suspect a second leak that is so small they need a microscope to verify: > "So far, we have found one place and suspect another, where as some kind of leak exists. We must bring a powerful microscope on a cargo spacecraft and use to examine this place. We are not totally certain so far," Solovyov said. IANAMS but that screams microfractures. The Zvezda is made largely of an aluminum magnesium alloy [1] that has a fatigue limit so even small repetitive stress can cause it to eventually fail. I'm curious whether this is wear and tear from just being in space and getting irradiated or if its repetitive mechanical stresses like a small tidal force as it orbits the earth. [1] https://weebau.com/iss/zvezda.htm https://weebau.com/iss/zvezda.htm
- bartread 6y agoIs it possible it could also be from constant heating and cooling cycles as it orbits?
- deleted 6y ago[deleted]
- HPsquared 6y agoThose are the cause of the stress cycles. Components don't expand/contact uniformly, resulting in deformation and therefore stress. This process goes through cycles, causing stress cycles which eventually cause the growth of cracks (fatigue).
- HenryKissinger 6y agoHave we invented a material that is resistant to these thermal cycles indefinitely, or at least within a range of temperatures of several thousand degrees? I'm never going to have my own Star Destroyer if we continue to use subpar materials.
- gizmo686 6y agoIs there any reason to park in at a Lagrange point instead of just a high orbit? There aren't that many Lagrange points, so we should probably avoid cluttering them with objects that don't need to be there.
- m4rtink 6y agoAt least for the Moon, the lunar orbit is generally unstable: https://en.m.wikipedia.org/wiki/Lunar_orbit https://en.m.wikipedia.org/wiki/Lunar_orbit
- gizmo686 6y agoYou don't need a stable orbit, just one that will keep it in our neighborhood and away from the atmosphere and congested orbits. Put it in a high orbit, and point a telescope at it every now and then to update our record of it's orbit. By the time we are ready to visit it, even if its orbit changed, its new orbit would not be any more inconvenient then where we left it.
- namibj 6y agoThe moon's lumpy gravity field actually causes the eccentricity of most orbits to raise quite fast, eventually bringing the periapsis below the surface (or the apoapsis on an escape trajectory, but I recall the former being more of an issue): https://www.youtube.com/watch?v=EadClM4Y45A https://www.youtube.com/watch?v=EadClM4Y45A
- rossmohax 6y agofrom what I've read Lagrange point isn't exactly a point, but a region where it's cheap (in terms of fuel) to stay. They are quite large.
- sandworm101 6y agoYou can orbit the lagrange point, vertically as seen from earth. In such orbits it functions as if it were a point source of gravity.
- lsllc 6y agoI think we need a "Space New Deal", I'm honestly saddened by the lack of progress in space in my lifetime. I mean we've done some great work, but we haven't made any giant leaps since getting to the moon 51.5 years ago. Thankfully, we do have SpaceX et. al. who really are making some big strides -- but how do we multiply & speed up that effort? ... sorry, I'm being selfish, but I really want to go to Mars.
- ska 6y ago> but how do we multiply & speed up that effort? I think it's pretty much politically impossible. The first big space push was mostly a political pissing match (i.e. not really driven by doing it for its own sake). It's pretty easy to come up with other major challenges that most people will consider more important that also aren't getting funding ... so private industry looks more likely to get some traction. States might get interested if/when those efforts start to get more interesting or threatening. Mars in your lifetime is implausible, but not impossible I suppose.
- NortySpock 6y agoChina's public plans include a semi-permanent base on the Moon. That oughta ruffle some feathers in Congress. Chinese paper on plant-based life support systems for extended crew stays. https://www.biorxiv.org/content/10.1101/2021.01.12.426282v1 https://www.biorxiv.org/content/10.1101/2021.01.12.426282v1
- Something1234 6y agoDid the Chinese build their own biosphere 2 (Arizona)?
- andi999 6y agoSince you mentioned biosphere 2, I was really surprised to learn the Steve Bannon was director for 2 years of the project.
- stretchcat 6y agoAre tidal forces a significant source of strain on the ISS, due to the size of the station putting different parts of it in slightly different orbits? And if so, would these forces be less at a lagrange point?
- MisterTea 6y ago> Parking it in L4 or L5 could keep it for future generations but it would be even more of a challenge to go visit. "If your planet has one or more broken down space stations on its lawn, you might be a redneck colony." (Sorry.)
- Waterluvian 6y agoThat's hilarious. Is that from anywhere beyond being a take on that one comedian's shtick?
- nitrogen 6y agoMissed opportunity to replace "lawn" with "Lagrange"
- ves 6y agoAlternatively, Lagrawnge
- derekp7 6y agoFor future spacecraft, would it be possible to have a double hull with a self-healing jell in the middle? (In concept, I'm thinking similar to tire sealer, something with clotting agents in it).
- theodric 6y agoThat'd stop the leaks but not mitigate the risk of catastrophic hull failure caused by untreated cracks originating from repeated thermal cycling stresses
- babs56 6y agoWhere do you get this information from? I would love to read more about it...
- deepsun 6y agoMake it robotic only. Stop/dump all life support, but leave manipulators/robots like Canadarm, and accept robotic add-ons and commercial sub-satellites.
- alex_duf 6y agoA good chunk (arguably the most important one) of the research is actually done on the live subjects that go up there. So you'd lose a lot of research capability.
- joshxyz 6y agoExciting times. The first wonder of the space: The ISS.