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The propulsion system of the Service Module (public relations name: Zvezda), part of the Russian side of the ISS, is refueled by Russian Progress spacecraft, and formerly by European Automated/Ariane Transfer Vehicle (ATV) spacecraft. Both Progress and ATV spacecraft deliver approximately 850 kg of propellant to the ISS. The Service Module uses storable ...


10

In addition to the standard operational refueling missions that are part of normal station-keeping operations, there have also been experiments performed that studied in-space refueling. In particular, three phases of the NASA Robotic Refueling Mission have been completed, which simulated on-orbit refueling of a satellite not designed for refueling. A module ...


8

Several things that KSP does not model: The challenges of actually docking two things mechanically together without a handy human such that the plumbing works (leaks have a tendency to go bang) The extra instrumentation required to dock with enough reliability to not risk the mission (need duplicate equipment). Notably for the ISS many craft just take ...


5

So the basic fact is that the delta-V from LEO to LLO (low lunar orbit) using a high-thrust system is about 4 km/s and using a low thrust system it's about 8. source So, using something like a vacuum raptor engine ($I_{sp}$ 382s) you need a mass ratio of about 2:1. That is, for every ton you want to deliver to LLO you need 2 tons of methalox in LEO. Using ...


3

The big problem with sending supplies and fuel ahead is that there's many ways it could go wrong which would end up with the crew being dead. There's no major advantage to sending supplies ahead of the mission to orbit another body, and a lot of risk. The thought is that you can split the cargoes and launch them in smaller, cheap rockets rather than ...


1

This is equivalent to asking "how much payload mass can Starship + Superheavy put into LEO per launch". It's just that in the case of a tanker the "payload" is fuel rather than cargo. At the moment that's actually a rather tricky question to answer, since the design of Starship and Superheavy are still constantly changing as the ...


1

I came to a similar conclusion. One launch to put the spaceship into orbit, 10 or more tankers to "fill the tanks". Maybe a dozen launches all together, each launch the equivalent of a Saturn V. There were only 13 Saturn V launches in all before they pulled the plug on the whole program. Direct ascent and Earth Orbit Rendezvous (EOR) were rejected in favor ...


1

I would expect that if a satellite had no special design for in-orbit propellant transfer then the initial list of options would centre around the normal ground propellant supply interface, normally referred to as a "Fill and Drain Valve", FDV. Typical characteristics of interest are: often has an internal valve that can be operated by a "...


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