Replying to old post- It actually seems like there may be a thin atmo on the Moon in the future, I can't figure out how the Fallen and Hive breath there otherwise; so the shooting stars could be justified. Other planets were terraformed, after all, maybe the Moon as well to a slight degree? Otherwise it's a case of "Batman Can Breathe In Space". (Also, we hear sound on the Moon- sound=air.) The gravity issues can be explained as future terraforming as well, the Traveller's science is magic. Gravity enhancement is not out of the question if you can turn Mercury into a garden world.