5 ms·

Unless you're stuffing orbit to the point of having an interceptor within every couple of sqkm (so millions if not billions of them, with active navigation of c

Unless you're stuffing orbit to the point of having an interceptor within every couple of sqkm (so millions if not billions of them, with active navigation of course), orbit is not a great place to put interceptors. They can't just sit over a location, so any given interceptor would on average be ~45 minutes away from the missile. On the other hand, if you're talking about having Starship launch interceptors in response to an incoming missile, it's entirely the wrong kind of rocket for the purpose. Being cryo-fueled makes it unrealistic to keep it sitting ready for launch, and it has way too low of a TWR for missile defense purposes. Missile defense systems need very high TWR, and hypergolic or solid fueled rockets, which can sit around fueled for years on end.

burnerthrow008 3y ago
ICBMs aren't uniformly randomly distributed across the globe, though. You would only need to cover a few selected orbital inclinations, corresponding to the latitude of the launch sites (albeit with a large number of RAs, but probably nothing more than what SpaceX already does for Starlink). The calculus is even better for the most-probable launch scenario, over-the-pole, since all the high-inclination interceptor orbits will converge in the same region as the ICBMs. For SBLMs the calculus is theoretically a bit less favorable, but most of Russia's SSNs will be in the Arctic Ocean anyway to avoid USN attack submarines.
- raisedbyninjas 3y ago
  ICBM boost phase only lasts about four minutes. Detection takes a minute or two. LEO orbit time is as low as 90 minutes, so you need at least 45 satellites orbiting the desired location to reach a single missile in time. This doesn't include orbit drift or account for the chances of the interceptor missing.
  - wmf 3y ago
    Interceptors don't go into orbit at all.
friend_and_foe 3y ago
You can do it with geostationary right?
- deleted 3y ago
  [deleted]
- dotnet00 3y ago
  That puts you even farther away from the missile than launching from Earth. ICBMs go up to ~400km, GEO is ~35000km high. Clearing ~34500km in the required ~1-2 minutes would require the interceptor to travel much faster than the fastest things ever launched by humanity.

burnerthrow008 3y ago

ICBMs aren't uniformly randomly distributed across the globe, though. You would only need to cover a few selected orbital inclinations, corresponding to the latitude of the launch sites (albeit with a large number of RAs, but probably nothing more than what SpaceX already does for Starlink). The calculus is even better for the most-probable launch scenario, over-the-pole, since all the high-inclination interceptor orbits will converge in the same region as the ICBMs. For SBLMs the calculus is theoretically a bit less favorable, but most of Russia's SSNs will be in the Arctic Ocean anyway to avoid USN attack submarines.

raisedbyninjas 3y ago
ICBM boost phase only lasts about four minutes. Detection takes a minute or two. LEO orbit time is as low as 90 minutes, so you need at least 45 satellites orbiting the desired location to reach a single missile in time. This doesn't include orbit drift or account for the chances of the interceptor missing.
- wmf 3y ago
  Interceptors don't go into orbit at all.

friend_and_foe 3y ago

You can do it with geostationary right?

deleted 3y ago
[deleted]
dotnet00 3y ago
That puts you even farther away from the missile than launching from Earth. ICBMs go up to ~400km, GEO is ~35000km high. Clearing ~34500km in the required ~1-2 minutes would require the interceptor to travel much faster than the fastest things ever launched by humanity.