Re: SPACE: Cycler orbits

Date: Wed Feb 20 2002 - 09:14:39 MST

Louis Newstrom writes:
> This idea seems great at first, but there are two downsides:
> 1) It wouldn't cut costs. The energy needed to go half-way to mars and
> then the rest of the way will be at least equal to the whole trip. The
> extra fuel needed to precicely dock with the cycler station will probably
> make such a trip MORE expensive than a straight shot.

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.

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.

> 2) At a distance half-way to mars, the cycler would have an orbit of 517.6
> days. Doesn't sound bad. But, as a result, it would line up with earth
> only every 3.4 years, and with mars only every 2.1 years. Assuming the
> average (half) wait for any arbitrary launch time, a trip to mars via the
> cycler would take 2.7 years. Since mars aligns with earth every 2.1 years,
> the cycler would slow down such trips. And as I pointed out, without saving
> any money.

That could be a problem... Is there only one cycler configuration? Also,
for people that's a long time, but for a lot of cargo, it doesn't matter.
Imagine, e.g., a cycler supplying a Mars base. The only point would be to
ferry bulk supplies continuously to Mars.

> The reason such stations have been proposed in the past is not to save money
> or energy, but to allow inadequate ships to get to mars. Assume a ship
> cannot carry enough food. The advantage of a cycler would be that several
> unmanned ships could be sent to rendevous with the cycler. Then when the
> manned ship goes, there will be an oasis with food along the journey.
> That's the reason to consider cyclers.

That's a good idea too and melds with that of using a cycler station as a
supply ferry. A manned mission to Mars could arrive there with large
quantities of "cycled" supplies already in place. This might cut down on
the need for fancy technology or even recycling and repairs. After all, if
you can cycle through enough spare parts...

I think the idea is good for another reason. It lends itself to a variety
of uses. A direct Mars mission would only be useful for that and probably
only to get there and maybe back. A cycler station could be used over and
over and even, I bet, "recycled" to other uses, since it would be a bona
fide space station or supply ferry.

Also, with such a system in place, you don't need to develop larger ships to
make the journey. The manned ship could just have enough to get to Mars
"high speed" and not have to carry much else beyond the supplies to get
there -- and maybe to get back, in case of an emergency -- but not the
supplies needed for a long stay on Mars.


Daniel Ust

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