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How does SpaceX's Dragon capsule get to the ISS? Does Dragon use the onboard Draco thrusters in order to raise its orbit to the station or does the second stage of the Falcon 9 perform the majority of necessary inclination, altitude, and speed changes?

I’ve heard the Soyuz spacecraft uses its onboard main engine to perform the transfers to the ISS but I don’t see an equivalent to this on board the Dragon.

(Side question: will this procedure change much with Dragon V2?)

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I assume that the Falcon second stage gets into something fairly close to the rendezvous orbit, but Dragon has just about the same maneuvering capability as Soyuz does.

I’ve heard the Soyuz spacecraft uses its onboard main engine to perform the transfers to the ISS but I don’t see an equaivalent to this onboard the Dragon.

The Dracos are the equivalent to the main propulsion on the Soyuz.

The Draco produces 400 N of thrust; four of them firing prograde produce 1.6 kN. Soyuz's main engine produces 2.94 kN, not quite twice as much.

The specific impulse (fuel efficiency) is about the same for the two, and with a full payload, Soyuz is about 11% propellant by mass and Dragon about 12.5% propellant.

So the Soyuz can accelerate a little more rapidly, but the total ∆v it can produce for orbital maneuvering is about the same.

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  • $\begingroup$ super concise-yet-complete answer! $\endgroup$ – uhoh Jan 1 at 2:06
  • $\begingroup$ Thank you very much for the response! I really appreciate it. $\endgroup$ – surminator Jan 1 at 4:05

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