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Would it reduce the cost/time to go to Mars with people if the transit vehicle was accelerated using less expensive means (i.e. ion engine and/or gravity assists), and the people got took a small quick vehicle to catch up?

More detailed example: Launch the transit vehicle (the space ship that will go to Mars) long before the people will actually start their voyage. Then use slow acceleration techniques (i.e. ion thruster and/or gravity assists) to speed up the transit vehicle. When the transit vehicle is going fast enough, send the people up in a small, quick craft to get on the transit vehicle.

If the transit vehicle stayed orbiting Earth, presumably it would have to be in an elliptical orbit. If the transit vehicle used gravity assists, presumably it could get much faster speeds than an elliptical orbit could produce and it would be harder to get the timing correct for the transit vehicle to pass Earth on its way to Mars.

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  • $\begingroup$ I'm pretty sure there was an idea for a (largely unpropelled) vehicle which would travel in an elliptical orbit with perihelion at Earth's orbital radius and aphelion at Mars. There was a 'synchronicity' of the three orbits which would allow the vehicle to pass by Earth and Mars every few orbits. Unfortunately I cannot recall what it was called. $\endgroup$ – Andrew Thompson Apr 28 '15 at 3:04
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    $\begingroup$ @AndrewThompson , I believe you are thinking of the Visit 1 and Visit 2 Cycler orbits. See en.wikipedia.org/wiki/Mars_cycler $\endgroup$ – HopDavid Apr 28 '15 at 4:07
  • $\begingroup$ EML2 is a good place to park the transit vehicle while waiting for human passengers. An object nudged from this location has the orbital energy of an elliptical orbit having a semi major axis of about a million kilometers. Nudging the payload moon ward from EML2 can given a lunar gravity assist and Oberth benefit to send send the spacecraft to a perigee deep in earth's gravity well. At perigee the spacecraft would be moving about 10.8 km/s and enjoy a huge Oberth benefit. $\endgroup$ – HopDavid Apr 28 '15 at 4:12
  • $\begingroup$ @HopDavid Yes, thanks, that was precisely what I was thinking of. $\endgroup$ – Andrew Thompson Apr 28 '15 at 6:06
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Yes. This has already been proposed by Landau and Strange, using a high-Earth orbit as the staging point. Our Moon provides a convenient and mostly free means of raising and lowering the periapsis of the orbit of the transit vehicle.

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