I don’t think bringing the ISS down in a controlled way is because of the risk that it might hit someone on earth, or because of “the PR disaster” of us “irrationally worrying more about the ISS hitting our home than we are getting in their car the next day”.
Space debris is a potentially material issue.
There are around 23,000 objects larger than 10 cm (4 inches) and about 100 million pieces of debris larger than 1 mm (0.04 inches). Tiny pieces of junk might not seem like a big issue, but that debris is moving at 15,000 mph (24,140 kph), 10 times faster than a bullet. (Source: PBS)
This matters because debris threatens satellites. Satellites are critical to GPS systems and international communication networks. They are used for things like helping you get a delivery, helping the emergency services get to their destination, or military operations.
Any one bit of space debris probably won’t cause a big deal if you ignore knock-on effects. However a phenomenon called Kessler Syndrome could make things much worse. This arises when space debris hits into satellites, causing more space debris, causing a vicious circle.
The geopolitics of space debris gets complicated.
The more space debris there is, the more legitimate it is to have weapons on a satellite (to keep your satellite safe from debris).
However such weapons could be dual-purpose, since attacking an enemy’s satellite could be of great tactical value in a conflict scenario.
I haven’t done a cost-effectiveness analysis to justify whether $1bn is a good use of that money, but I think it’s more valuable than this article seems to suggest.
I’m deeply concerned about space debris, but I don’t think it alone could justify this project. A ‘controlled’ descent sounds like it’s about targeting a specific landing spot—an ‘uncontrolled’ descent could still lower the ISS sufficiently fast as to minimise its chance of hitting orbiting debris (it probably lowers it faster!).
Also the ISS is also already well within Earth’s atmosphere, and the lower it gets, the shorter the life of debris hitting it would be due to atmospheric resistance, and it would presumably be relatively easy to control it from hitting anything near the start of its descent, when you can choose when to start the process and only run serious risk as it started to lose control 0 in the lower, thicker atmosphere.
The ISS itself isn’t particularly likely to create space debris (its orbit is already lower than major constellations and anything with thrusters is going to move out the way, and if it breaks up as it hits the upper atmosphere the pieces will rain over earth rather than remain in orbit). But tens of thousands of other satellites being launched this decade have plenty of potential to create space debris, space is a commons and space law is by international treaty with lots of blank spaces (unlike, for example, the heavily-regulated airspace).
If the deorbiting strategy for the ISS is “we decided that to save a third of the annual budget we usually put in, we’d do a reentry with limited control from its onboard thrusters because only a few islands might get hit, and in fact even though we missed the target we didn’t hurt anything except an abandoned chicken shed”, or “we left it to Roscosmos to figure out”[1] nobody is going to listen to NASA’s guidelines for a safer space (not even Congress). Especially since all the precautions everyone else might need to take will cost them significant money.
there are other political considerations to leaving it to Roscosmos to figure out of course, even though they’re hardly likely to target California with it, and tech developed to deorbit the ISS isn’t going to be more useful as an antisatellite weapon than dozens of existing civil projects to create tugs for deorbiting and servicing defunct smaller satellites)
I understand why the international community doesn’t see it this way because they meld the two together, but I would distinguish between safe space, and safe people on earth. Space governance vs. earth governance
You’ve said that space is a commons, and space law is international treaty—what does a re-entry have to do with this that doesn’t affect space? From my perspective safety of people on earth has nothing much to do with the governance and safety of space, so shouldn’t necessarily be part of the political discussion about responsible space debris.
But 100% I can see how those 2 things get connected politically, like “if you are willing to be loose with your huge space station, why should we pay more to stop our satellites becoming space debris?” Even though one of those things is about Earth governance and the other space.
Ultimately the safety of the space domain and safety on earth from space debris are linked by both overlapping technologies for monitoring and mitigation and the overlapping principle that entities ought to take responsibility for what they put into space. And from that perspective it would be pretty hard to lecture foreign universities on why they should spend a few grand on safely deorbiting their Cubesat to mitigate a very small risk of hitting other satellites whilst being the entity that decided to abdicate responsibility for safely deorbiting the ISS to mitigate a very small risk of hitting a densely populated urban area—to save a lot more money but still only about 4 months of ISS budget.
Ultimately they’re optimising for technological potential rather than saving lives, and the budget for this is far more closely linked to debates like “but we can’t trust the Russians to manage the deorbiting process, can we”, “does it have commercialization potential” and “could it be turned into an ASAT weapon” than “would it save more lives than the debris could possibly threaten if we bought $843m worth of medicine instead?”
Is interesting that many people are taking about space debris when NASA don’t mention that as a consideration in the mode of coming down. Do you have a link which states that add an issue?
Sanjay’s link about Kessler Syndrome above describes the problem. If you mean about the ISS specifically, I think it’s just an instance of the general concern.
Oh I think I get it now, I was confused by “don’t think it alone could justify this project” because from what I can see it isn’t a consideration at all
Right, sorry. Yeah, I have no view on whether it’s a consideration at all, just that it seems unlikely to be a primary one from my rudimentary understanding of the issue.
Thanks Sanjay—I’m going off NASA’s public facing materials, where they don’t mention space debris as a potential consideration in controlled vs. Uncontrolled descent. They mention that as a reason why they don’t destroy it in situ or try and take the ISS to higher orbit.
I completely agree, if space debris was a serious consideration then it would be a while different equation.
I don’t think bringing the ISS down in a controlled way is because of the risk that it might hit someone on earth, or because of “the PR disaster” of us “irrationally worrying more about the ISS hitting our home than we are getting in their car the next day”.
Space debris is a potentially material issue.
There are around 23,000 objects larger than 10 cm (4 inches) and about 100 million pieces of debris larger than 1 mm (0.04 inches). Tiny pieces of junk might not seem like a big issue, but that debris is moving at 15,000 mph (24,140 kph), 10 times faster than a bullet. (Source: PBS)
This matters because debris threatens satellites. Satellites are critical to GPS systems and international communication networks. They are used for things like helping you get a delivery, helping the emergency services get to their destination, or military operations.
Any one bit of space debris probably won’t cause a big deal if you ignore knock-on effects. However a phenomenon called Kessler Syndrome could make things much worse. This arises when space debris hits into satellites, causing more space debris, causing a vicious circle.
The geopolitics of space debris gets complicated.
The more space debris there is, the more legitimate it is to have weapons on a satellite (to keep your satellite safe from debris).
However such weapons could be dual-purpose, since attacking an enemy’s satellite could be of great tactical value in a conflict scenario.
I haven’t done a cost-effectiveness analysis to justify whether $1bn is a good use of that money, but I think it’s more valuable than this article seems to suggest.
I’m deeply concerned about space debris, but I don’t think it alone could justify this project. A ‘controlled’ descent sounds like it’s about targeting a specific landing spot—an ‘uncontrolled’ descent could still lower the ISS sufficiently fast as to minimise its chance of hitting orbiting debris (it probably lowers it faster!).
Also the ISS is also already well within Earth’s atmosphere, and the lower it gets, the shorter the life of debris hitting it would be due to atmospheric resistance, and it would presumably be relatively easy to control it from hitting anything near the start of its descent, when you can choose when to start the process and only run serious risk as it started to lose control 0 in the lower, thicker atmosphere.
The ISS itself isn’t particularly likely to create space debris (its orbit is already lower than major constellations and anything with thrusters is going to move out the way, and if it breaks up as it hits the upper atmosphere the pieces will rain over earth rather than remain in orbit). But tens of thousands of other satellites being launched this decade have plenty of potential to create space debris, space is a commons and space law is by international treaty with lots of blank spaces (unlike, for example, the heavily-regulated airspace).
If the deorbiting strategy for the ISS is “we decided that to save a third of the annual budget we usually put in, we’d do a reentry with limited control from its onboard thrusters because only a few islands might get hit, and in fact even though we missed the target we didn’t hurt anything except an abandoned chicken shed”, or “we left it to Roscosmos to figure out”[1] nobody is going to listen to NASA’s guidelines for a safer space (not even Congress). Especially since all the precautions everyone else might need to take will cost them significant money.
there are other political considerations to leaving it to Roscosmos to figure out of course, even though they’re hardly likely to target California with it, and tech developed to deorbit the ISS isn’t going to be more useful as an antisatellite weapon than dozens of existing civil projects to create tugs for deorbiting and servicing defunct smaller satellites)
I agree with all this. I was just commenting on the issue of debris specifically.
Thanks David yes I think I understand this now!
I understand why the international community doesn’t see it this way because they meld the two together, but I would distinguish between safe space, and safe people on earth. Space governance vs. earth governance
You’ve said that space is a commons, and space law is international treaty—what does a re-entry have to do with this that doesn’t affect space? From my perspective safety of people on earth has nothing much to do with the governance and safety of space, so shouldn’t necessarily be part of the political discussion about responsible space debris.
But 100% I can see how those 2 things get connected politically, like “if you are willing to be loose with your huge space station, why should we pay more to stop our satellites becoming space debris?” Even though one of those things is about Earth governance and the other space.
Ultimately the safety of the space domain and safety on earth from space debris are linked by both overlapping technologies for monitoring and mitigation and the overlapping principle that entities ought to take responsibility for what they put into space. And from that perspective it would be pretty hard to lecture foreign universities on why they should spend a few grand on safely deorbiting their Cubesat to mitigate a very small risk of hitting other satellites whilst being the entity that decided to abdicate responsibility for safely deorbiting the ISS to mitigate a very small risk of hitting a densely populated urban area—to save a lot more money but still only about 4 months of ISS budget.
Ultimately they’re optimising for technological potential rather than saving lives, and the budget for this is far more closely linked to debates like “but we can’t trust the Russians to manage the deorbiting process, can we”, “does it have commercialization potential” and “could it be turned into an ASAT weapon” than “would it save more lives than the debris could possibly threaten if we bought $843m worth of medicine instead?”
Thanks David this is excellent. Have added a sentence (crediting you) in the main body which hopefully reflects your point here.
Is interesting that many people are taking about space debris when NASA don’t mention that as a consideration in the mode of coming down. Do you have a link which states that add an issue?
Sanjay’s link about Kessler Syndrome above describes the problem. If you mean about the ISS specifically, I think it’s just an instance of the general concern.
I get that it’s a big problem in general, but NASA haven’t discussed it as a Factor in controlled vs. uncontrolled reentry.
It seems like it might not be, for the reasons I suggested or others?
Oh I think I get it now, I was confused by “don’t think it alone could justify this project” because from what I can see it isn’t a consideration at all
Right, sorry. Yeah, I have no view on whether it’s a consideration at all, just that it seems unlikely to be a primary one from my rudimentary understanding of the issue.
Thanks Sanjay—I’m going off NASA’s public facing materials, where they don’t mention space debris as a potential consideration in controlled vs. Uncontrolled descent. They mention that as a reason why they don’t destroy it in situ or try and take the ISS to higher orbit.
I completely agree, if space debris was a serious consideration then it would be a while different equation.