They just fired their rockets to compensate for the inertia.<p>If you want recoiless weapons in space, you could probably just buy a 1960&#x27;s era Gyrojet pistol or rifle.  The launched rocket powered bullets instead of conventional ammo and because the rocket ammunition was self-propelled, it was nearly recoiless.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Gyrojet" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Gyrojet</a><p>Also, the weapons, especially the rifle, have this wonderful 1960&#x27;s era futurist design to them.  The Gyrojet weapons are probably worthy of their own posting.