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oz6702 t1_j5xlhp5 wrote

Reply to comment by fishling 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 sample return mission is almost certainly not going to be coming on a path aligned with the ISS orbit that only needs to slow 4 km/s to meet it.

To be fair, this is a trivially easy problem to solve. A change of a few cm/s when you're a million clicks away can result in huge differences in your destination, so setting things up such that your incoming deep space probe lines up with the ISS' direction of orbit and plane of orbit and whatnot would be quite easy, and pretty cheap as far as dV is concerned. Still, slowing down to match orbit with the ISS is something that's gonna cost you a ton of fuel either way - unless you aerobrake, in which case you might as well just do that instead of bring the fuel along to begin with.

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Nemisis_the_2nd t1_j5y7nt7 wrote

> Still, slowing down to match orbit with the ISS is something that's gonna cost you a ton of fuel either way

Aerobraking, as you suggest, is the answer. It's how we used to do it for a long time before more effective technology and better understanding of orbital trajectories came along.

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