Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
Wikipedia indicates that the Salyut 3 was launched with a gun, which could have been used in self-defense or against other satellites, and which was actually tested after the last crew had departed in the Soyuz 15.
Is this the only example of a gun being deployed onboard a spacecraft? Elsewhere, Wikipedia indicates that the unflown OPS-4 station would have been equipped with a different space-to-space system, which would have fired missiles - but I have not come across any other such examples.
Salyut 3 is the only publicly acknowledged space to space weapon that has been orbited. It's possible that there are others which have been deployed in secret. The outer space treaty does not prohibit the deployment of conventional weapons in space, there doesn't seem to be any hurry to do it though, which is a good thing.
Space to Space weapons seemed like a good idea, but really isn't that great for orbiting spacecraft. First of all, what is the use case? It would only really work for spacecraft in a similar orbit. Let's imagine that a spacecraft is coming towards you. Firing weapons to destroy the spacecraft might lead to an impact in the firing spacecraft, destroying it. It sounds cool, and as much of the early space program lead to the desire to have such weapons, it has since been discarded as a useful idea.
Space.com has a list of the top 10 unclassified space weapons. Of these, the only non-theoretical weapon was that possessed by Salyut, or anti-satellite technology launched by ground based facilities. So for now, weapons in space have not been launched, beyond the Salyut mission.
