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> The Air Force X-37B is not a missile or weapon. No, but that seems a little bit disingenuous. Aircraft carriers are neither missiles nor weapons either. We

> The Air Force X-37B is not a missile or weapon. No, but that seems a little bit disingenuous. Aircraft carriers are neither missiles nor weapons either. We can recognize things as military assets that are neither missiles nor weapons. The X-37B is a DOD asset, operated by the military, capable of deploying weapons systems. In that way, it is part of the military capability of the US.

cryptonector 6y ago
It would be silly to use the X-37 as an anti-sat weapon: it's too expensive. Think of how cheaply SpaceX is putting up Starlink! A single Falcon 9 could probably put up a bunch (20? 30?) of antisat weapons that only ever raise or lower their orbits and fire .22s at their targets. The idea is to disable targets with as little debris as possible. With larger anti-sat sats you could actually latch on to the target and de-orbit it for zero orbital debris destruction. This requires many more, much larger such devices because while it takes relatively little delta-v to raise or lower an orbit, it takes a lot more to match an arbitrary target's orbit (to which more fuel has to be added for de-orbiting).
- knodi123 6y ago
  Just having a theoretical conversation now, but > antisat weapons that only ever raise or lower their orbits and fire .22s at their targets. raising your orbit is the hard and expensive part, it takes a lot of propellant, which generally rules out smaller vehicles, right? And if you want to destroy a satellite, you need a lot of kinetic energy, which for a tiny projectile means lots of speed relative to the target... But since your absolute speed determines the height of your orbit, the only way to get more than ~1000 ft/s is to have your gun-sat in an opposite-direction orbit to the target, right? And isn't it the case that our satellites are all orbiting in more or less the same direction, since they launch from canaveral and have to head east to be over water?
  - enkid 6y ago
    What if you used an object in another orbit to fire a projectile? Wouldn't that make the differences in energies pretty significant?
    - knodi123 6y ago
      I did suggest "have your gun-sat in an opposite-direction orbit to the target". Yes, that would dramatically increase the kinetic energy.
  - tankenmate 6y ago
    The only issue is that using kinetic weapons greatly increases the risk of Kessler Syndrome; in other words premature mutually assured destruction. Kinetic space weapons are so easy to get wrong with outsized repercussions. Otherwise raising orbit is expensive(ish) depending on whether you want a circular orbit. Matching an orbit can be expensive. If the target has auto avoidance like Starlink does then matching orbit becomes war of attrition; even getting the target to burn off its fuel is a win as it will drastically shorten its life span. Deorbiting is relatively easy at LEO, just increasing frontal area is a cheap way to achieve it. Above LEO would normally require fuel of some amount.
  - lutorm 6y ago
    You don't really need a lot of kinetic energy, it's not like satellites are armored. I'd think a pretty small kinetic energy, like a rifle bullet, would do it (depending on where it hit, obviously.) The trick is delivering that small kinetic energy...
  - marsokod 6y ago
    Changing the altitude is fine, with all the electric propulsion that is available nowadays. You just need enough power and that means big deployables. The main issue is orbital plane changes, meaning that in the future, satellite-to-satellite weapons will not rendez-vous with the target but just do a quick approach while being on a different orbit and send/drop a low speed projectile to collide with the target. All this is already possible on a 100kg-class satellite.
  - deleted 6y ago
    [deleted]
- jburgess777 6y ago
  > it’s too expensive. Can you identify a time when cost was obviously a signifcant factor in a military choice? To me it seems that cost is low in the grand scheme of things.
  - cryptonector 6y ago
    Cost is not no object to the military. If they could have 1,000 asat sats, they'd want to have 1,000. Can you imagine them saying "sure, let's just have an X-37B, one, just one, it will do"? If you need these in a shooting war, 1 ain't gonna be enough. You need lots of them. You can't have lots of them if: they're big and heavy (launches are too infrequent and too expensive) or if they're too expensive (you want 1,000 but can only afford 10).
m4rtink 6y ago
Actually back in the day the Soviets were genuinely afraid of the Space Shuttle, as they though that due to it's capability for sudden orbit changes via aerodynamic surfaces. They thought it might start on an otherwise routine mission only to do a sudden orbit change that makes it fly over Moscow & nuke it with hardly any warning at all. It is said that was also the reason they started the Buran and Energia project - while their engineers though the Space Shuttle was too complicated, expensive and dangerous (and they were right...) they also though there must be something special about it, otherwise the Americans would not build something that bad.
- coolspot 6y ago
  I am pretty sure that engineers of a country that has sent first man to orbit, built first space station, got first pictures from lunar and venus surfaces, those engineers knew very well that “sudden orbit changes via aerodynamic surfaces” can’t be done in a vacuum. They have seen some dangers like sattelite theft and others, so they have built a vehicle with similar capacity just because you have to match the opponent, even if the idea doesn’t really work and there are more efficient ways of achieving same results.
  - sobellian 6y ago
    It appears that the study was considering the shuttle's ability to glide while re-entering. They were afraid a shuttle could launch from Vandenberg and do a maneuver similar to the shuttle's once-around abort and approach the USSR from the south (most of their early-warning systems were facing north) and possibly even return home afterwards. It's a cute theory but you should be skeptical of the claim that this study was the motivation for the Soviet shuttle program.
    - mandevil 6y ago
      The main thing necessary to understand Buran is... why the big heavy delta wings? It is clear why the US shuttle has them: Reference Mission 3A/3B, which the USAF added to the design requirements in exchange for political cover in Congress (see T.A. Heppenheimer, _The Space Shuttle Decision_). If you launch due south from Vandenberg and you need to return back to your landing site (either because of the Reference Mission or because of a Abort-Once-Around) you have to be able to move roughly 1/16 of the Earth's diameter in the atmosphere (otherwise you end up in the Pacific Ocean), and that forces you to the big heavy delta wings that sacrifices a lot of payload. But why did the Soviets need that much cross-range? First of all their spy satellites were not generally put into polar orbits (they used shorter lived satellites that didn't need sun synchronous orbits) and second of all, one polar orbit around from Baikonur runs right over Russian land rather than the Pacific Ocean, so they had no need for all of that cross range. The only thing that makes sense to me is that a design goal for Buran was "copy the STS, but don't do quite as many silly things" because I simply can't find a use case for that much cross range for them.

cryptonector 6y ago

It would be silly to use the X-37 as an anti-sat weapon: it's too expensive. Think of how cheaply SpaceX is putting up Starlink! A single Falcon 9 could probably put up a bunch (20? 30?) of antisat weapons that only ever raise or lower their orbits and fire .22s at their targets. The idea is to disable targets with as little debris as possible. With larger anti-sat sats you could actually latch on to the target and de-orbit it for zero orbital debris destruction. This requires many more, much larger such devices because while it takes relatively little delta-v to raise or lower an orbit, it takes a lot more to match an arbitrary target's orbit (to which more fuel has to be added for de-orbiting).

knodi123 6y ago
Just having a theoretical conversation now, but > antisat weapons that only ever raise or lower their orbits and fire .22s at their targets. raising your orbit is the hard and expensive part, it takes a lot of propellant, which generally rules out smaller vehicles, right? And if you want to destroy a satellite, you need a lot of kinetic energy, which for a tiny projectile means lots of speed relative to the target... But since your absolute speed determines the height of your orbit, the only way to get more than ~1000 ft/s is to have your gun-sat in an opposite-direction orbit to the target, right? And isn't it the case that our satellites are all orbiting in more or less the same direction, since they launch from canaveral and have to head east to be over water?
- enkid 6y ago
  What if you used an object in another orbit to fire a projectile? Wouldn't that make the differences in energies pretty significant?
  - knodi123 6y ago
    I did suggest "have your gun-sat in an opposite-direction orbit to the target". Yes, that would dramatically increase the kinetic energy.
- tankenmate 6y ago
  The only issue is that using kinetic weapons greatly increases the risk of Kessler Syndrome; in other words premature mutually assured destruction. Kinetic space weapons are so easy to get wrong with outsized repercussions. Otherwise raising orbit is expensive(ish) depending on whether you want a circular orbit. Matching an orbit can be expensive. If the target has auto avoidance like Starlink does then matching orbit becomes war of attrition; even getting the target to burn off its fuel is a win as it will drastically shorten its life span. Deorbiting is relatively easy at LEO, just increasing frontal area is a cheap way to achieve it. Above LEO would normally require fuel of some amount.
- lutorm 6y ago
  You don't really need a lot of kinetic energy, it's not like satellites are armored. I'd think a pretty small kinetic energy, like a rifle bullet, would do it (depending on where it hit, obviously.) The trick is delivering that small kinetic energy...
- marsokod 6y ago
  Changing the altitude is fine, with all the electric propulsion that is available nowadays. You just need enough power and that means big deployables. The main issue is orbital plane changes, meaning that in the future, satellite-to-satellite weapons will not rendez-vous with the target but just do a quick approach while being on a different orbit and send/drop a low speed projectile to collide with the target. All this is already possible on a 100kg-class satellite.
- deleted 6y ago
  [deleted]
jburgess777 6y ago
> it’s too expensive. Can you identify a time when cost was obviously a signifcant factor in a military choice? To me it seems that cost is low in the grand scheme of things.
- cryptonector 6y ago
  Cost is not no object to the military. If they could have 1,000 asat sats, they'd want to have 1,000. Can you imagine them saying "sure, let's just have an X-37B, one, just one, it will do"? If you need these in a shooting war, 1 ain't gonna be enough. You need lots of them. You can't have lots of them if: they're big and heavy (launches are too infrequent and too expensive) or if they're too expensive (you want 1,000 but can only afford 10).

m4rtink 6y ago

Actually back in the day the Soviets were genuinely afraid of the Space Shuttle, as they though that due to it's capability for sudden orbit changes via aerodynamic surfaces. They thought it might start on an otherwise routine mission only to do a sudden orbit change that makes it fly over Moscow & nuke it with hardly any warning at all. It is said that was also the reason they started the Buran and Energia project - while their engineers though the Space Shuttle was too complicated, expensive and dangerous (and they were right...) they also though there must be something special about it, otherwise the Americans would not build something that bad.

coolspot 6y ago
I am pretty sure that engineers of a country that has sent first man to orbit, built first space station, got first pictures from lunar and venus surfaces, those engineers knew very well that “sudden orbit changes via aerodynamic surfaces” can’t be done in a vacuum. They have seen some dangers like sattelite theft and others, so they have built a vehicle with similar capacity just because you have to match the opponent, even if the idea doesn’t really work and there are more efficient ways of achieving same results.
- sobellian 6y ago
  It appears that the study was considering the shuttle's ability to glide while re-entering. They were afraid a shuttle could launch from Vandenberg and do a maneuver similar to the shuttle's once-around abort and approach the USSR from the south (most of their early-warning systems were facing north) and possibly even return home afterwards. It's a cute theory but you should be skeptical of the claim that this study was the motivation for the Soviet shuttle program.
  - mandevil 6y ago
    The main thing necessary to understand Buran is... why the big heavy delta wings? It is clear why the US shuttle has them: Reference Mission 3A/3B, which the USAF added to the design requirements in exchange for political cover in Congress (see T.A. Heppenheimer, _The Space Shuttle Decision_). If you launch due south from Vandenberg and you need to return back to your landing site (either because of the Reference Mission or because of a Abort-Once-Around) you have to be able to move roughly 1/16 of the Earth's diameter in the atmosphere (otherwise you end up in the Pacific Ocean), and that forces you to the big heavy delta wings that sacrifices a lot of payload. But why did the Soviets need that much cross-range? First of all their spy satellites were not generally put into polar orbits (they used shorter lived satellites that didn't need sun synchronous orbits) and second of all, one polar orbit around from Baikonur runs right over Russian land rather than the Pacific Ocean, so they had no need for all of that cross range. The only thing that makes sense to me is that a design goal for Buran was "copy the STS, but don't do quite as many silly things" because I simply can't find a use case for that much cross range for them.