fyrstormer
fyrstormer t1_j5xdodu wrote
Reply to Why do sample return missions such as OSIRIS-REx use their own reentry vehicles instead of just going to the space station for pickup and return with ISS equipment? by PromptCritical725
The return vehicle would have to carry a HUGE amount of fuel to slow down enough to dock with a space station in orbit. The return vehicle has been falling towards Earth for millions of miles and it's moving incredibly fast by the time it gets here. The most economical way to bring it to a stop is to let it shove a few thousand miles of Earth's atmosphere out of the way, rather than firing expensive retro-rockets.
fyrstormer t1_itz6gad wrote
Reply to The Ego Siphon, by me by GenericOnlineName
YUMMAY
fyrstormer t1_j5xdz36 wrote
Reply to comment by ninthtale in Why do sample return missions such as OSIRIS-REx use their own reentry vehicles instead of just going to the space station for pickup and return with ISS equipment? by PromptCritical725
The Moon has a tiny amount of gravity compared to the Earth, so lander modules falling towards the Moon don't speed up nearly as much and don't need nearly as much fuel to slow them down before they land. The Apollo Lunar Module was a single-stage-to-land/single-stage-to-orbit aluminum box with a little rocket motor strapped to the underside; the same setup on the surface of the Earth wouldn't even be able to lift its own weight.