From: neptune@mars.superlink.net
Date: Wed Feb 20 2002 - 13:24:26 MST
Louis Newstrom writes:
>> 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
> the
>> 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.
I see. Good old laws of physics...
>> The idea is, I think, to use the cycle more as a cheap way to ferry
> supplies
>> 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
> destination.
>
> True. But the energy cost per item remains the same. You are just
> dividing that energy cost among several trips.
The total cost of all the trips might be the same or higher as one big trip,
but the fact is we have small rockets right now and small payloads. It's
kind of like the poor man's choice of buying one serving of rice at a time
instead of a months' supply...
> 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.
An interesting idea. We'd also have to know about the particular asteroid
-- depending on the goals here. After all, Eros appears to be covered with
dust and small rocks. Impacting it might result in a lot material being
kicked up -- a hazard to many operations.
How could we find out what a particular asteroid is like before attempting
such an impact? Perhaps a smaller probing impact?
>> 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.
The site Anders cited gave what appeared to be another configuration. In
fact, IIRC, the cycler proposed changed orbital configurations to suit
travelers...
Cheers!
Daniel Ust
http://uweb.superlink.net/neptune/
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