Recent comments in /f/askscience

TryingNot2BeToxic t1_j5xew3p wrote

Reply to comment by electric_ionland 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

Oh this brings up an interesting problem when it comes to an intermediary moon base/launch platform. Would the propellant needed in order to reduce speed to land back on the moon offset the propellant saved from launching in lower gravity/no atmosphere?

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NetworkLlama t1_j5xeh9a wrote

Reply to comment by crazunggoy47 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

That actually happened with the Genesis mission to collect samples from the solar wind. It hit the atmosphere at 11 km/s, but after slowing down, the parachutes never deployed. It impacted the ground at 86 m/s, contaminating most but not all of the collectors, and some of the science was salvaged.

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Jayhawks190 t1_j5xef3y wrote

Reply to Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology by AutoModerator

Philosophy: I would like for you to please argue the merits against killing the rich until they care about the poor in the modern era while keeping your eye on the rearview mirror of human history and acknowledging that violence is how societies have handled these problems in the past. Convince me the guillotine isn’t the solution to eating caking.

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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.

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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.

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stickmanDave t1_j5xc4kn wrote

Reply to comment by janoc 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

If it was coming in on a trajectory to decelerate and end up at the space station, then failing to decelerate would result in it passing nowhere near the space station.

Remember, the space station isn't a stationary target. It's tooling a long at 7km/second or so. Everything has to go exactly according to plan for the two to end up at the same place at the same time.

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