Re: SPACE: Cycler orbits

From: Louis Newstrom (
Date: Wed Feb 20 2002 - 10:37:55 MST

From: <>

> I'm not sure about the latter claim. After all, if the cycler station was
> more like a storage depot, each individual trip to it might use a lot less
> fuel than a straight shot to Mars. Why? The mass would be smaller for
> ship docking to the cycler station.

Imaging a station that orbits in such a way that it goes near earth and
mars. (We'll call this the "cycle orbit".) Sending a ship to rendevous
with the cycler station is EXACTLY the same as putting the shp in the "cycle
orbit". You have gained nothing (energy-wise) by having a station already
orbiting at that same spot.

Now, I'll admit that with a station, the trip will be more pleasant. I'm
just saying it won't save you energy.

> The idea is, I think, to use the cycle more as a cheap way to ferry
> and maybe people back and forth. One can make several small trips to a
> cycler station -- rather than one big one to the station or the

True. But the energy cost per item remains the same. You are just dividing
that energy cost
among several trips.

A similar but different scenario is to use an asteroid. Instead of
"landing" on the asteroid, you just get in the way and "crash" on the
asteroid. In this way, you don't have to expend the energy to match speeds.
(You just have to have enough padding to survive the crash.) This would
eventually change the asteroid's orbit after many crashes, but the time to
do that might be years or centuries.

> > 2) At a distance half-way to mars, the cycler would have an orbit of
> > days.

> That could be a problem... Is there only one cycler configuration?

My exmple time was a circular orbit. I think (but haven't done the math)
that an eccentric orbit that touched both orbits would have a period similar
to this average.

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