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odddutchman t1_j5w958r 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

Strictly speaking, they don't get the atmospheric braking for free...still needs a heatsheild and guidance system; but they don't have to drag extra mass of fuel, rocket engines, etc with them during the ascent part of the flight...which adds up REALLY fast. Look up "the tyranny of the rocket equation".

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17934658793495046509 t1_j5wpij1 wrote

Also you would need a heat shield to slow down in the atmosphere. It’s heavy but weighs less than the fuel you would need to do the same thing.

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Hokulewa t1_j5x1h2j wrote

You could really improve your payload mass margin by using aerobraking to match velocity with the Earth, but you would need a shielding device of some kind to protect you from the heat. That would weigh a lot less than the propellant you'd need to use, otherwise.

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