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History: America puts it up to help target ICBMs, etc. US taxpayers/military give it away for free as a gesture of good will which also has political benefits.

JumpCrisscross 3y ago
> America puts it up to help target ICBMs Modern ICBMs use GNSS. Historically, they didn’t. Certainly not when the GPS constellation was deployed.
- philipkglass 3y ago
  Modern ICBMs use GNSS. Do they? The US hasn't deployed a new generation of ICBMs since the GPS constellation became operational. I would also expect that plans for nuclear war wouldn't rely on vulnerable satellites remaining operational. I thought that US weapons used GPS guidance as a low-cost alternative to other guidance methods in forgiving environments that don't have electronic warfare countermeasures (e.g. fighting the Taliban or armed forces equipped with old gear).
whartung 3y ago
GPS is important to the military, but many modern combat systems can get along without it. Most systems that use it have some manner of backup. GPS in combat debuted during the Gulf War, but mostly as a backup for navigation rather than targeting. We did not have 100% coverage back then, all of the satellites were not up yet.
- AstralStorm 3y ago
  You did have 100% coverage back then, but not high quality all of the time. In some rare cases only a single satellite pseudofix would have been available. That can still be accurate if the location device carries a decent synchronized clock. IOC was defined as always being in sight of 3 or more satellites, plus maintenance capability. That was achieved in 1993.
- ianburrell 3y ago
  There are reports from Ukraine of guided shells not working when GPS is jammed. I thought that most guided munitions have inertial guidance and GPS was to improve accuracy but maybe that doesn’t fit in artillery shell. I was reading that with MLRS that the launch location can be entered manually.
fsh 3y ago
ICBMs are probably the only part of the military that doesn't need GPS. Star trackers are more than accurate enough for that.

JumpCrisscross 3y ago

> America puts it up to help target ICBMs Modern ICBMs use GNSS. Historically, they didn’t. Certainly not when the GPS constellation was deployed.

philipkglass 3y ago
Modern ICBMs use GNSS. Do they? The US hasn't deployed a new generation of ICBMs since the GPS constellation became operational. I would also expect that plans for nuclear war wouldn't rely on vulnerable satellites remaining operational. I thought that US weapons used GPS guidance as a low-cost alternative to other guidance methods in forgiving environments that don't have electronic warfare countermeasures (e.g. fighting the Taliban or armed forces equipped with old gear).

whartung 3y ago

GPS is important to the military, but many modern combat systems can get along without it. Most systems that use it have some manner of backup. GPS in combat debuted during the Gulf War, but mostly as a backup for navigation rather than targeting. We did not have 100% coverage back then, all of the satellites were not up yet.

AstralStorm 3y ago
You did have 100% coverage back then, but not high quality all of the time. In some rare cases only a single satellite pseudofix would have been available. That can still be accurate if the location device carries a decent synchronized clock. IOC was defined as always being in sight of 3 or more satellites, plus maintenance capability. That was achieved in 1993.
ianburrell 3y ago
There are reports from Ukraine of guided shells not working when GPS is jammed. I thought that most guided munitions have inertial guidance and GPS was to improve accuracy but maybe that doesn’t fit in artillery shell. I was reading that with MLRS that the launch location can be entered manually.

fsh 3y ago

ICBMs are probably the only part of the military that doesn't need GPS. Star trackers are more than accurate enough for that.