Re: Venusian orbital carbon industry?

On 9 Nov 2005 07:43:46 -0800, "IsaacKuo" <mechdan@xxxxxxxxx> wrote:
>Bryan Derksen wrote:
>> A mass
>> driver hanging from high-altitude balloons would probably be a better
>> approach, with the bonus that solar panels will be a whole lot easier
>> to mount on gigantic balloons than on a vehicle that has to keep
>> dipping into high-velocity plasma on a regular basis. No drag
>> problems, and no ablation or thermal stresses to worry about.
>
>Gigantic balloons are pretty difficult technology to deal with even
>here on Earth. I can't think of any reason to think they'd be easier
>to deal with on Venus. Heck, we don't even know whether there's
>lightning on Venus, much less how much of a long term hazard it
>would be to Venusian atmospheric vehicles.

We have a heck of a lot more experience with balloon technology than
we do with "skimmer" spacecraft that dip in and out of the atmosphere
repeatedly.

>Mass drivers are also immature technology, and they only get you
>"halfway" to orbit. Somehow you need an orbital insertion maneuver.

Again, far more mature a technology than the atmosphere-dipper. We've
actually built mass drivers. As for the orbital insertion maneuver,
you're launching cannisters of pressurized reaction mass. Use a gas
rocket of some sort. Or if that's too flagrantly wasteful, have your
electric-rocket-powered spacecraft up there catching them and giving
them boosts. We've nearly got orbital tugs with today's technology
too.

>In principle, I agree that if all the technology can work out that a
>mass driver based aircraft system may be more efficient overall.
>But in terms of near term doable technology, it's not even on
>the table.

But it _is_ on the table with near-term doable technology, as far as I
can tell. There are companies planning to put up similar sorts of
vehicles here on Earth in the near future. See for example

http://en.wikipedia.org/wiki/Stratellite
http://en.wikipedia.org/wiki/WALRUS_HULA

(http://www.stratellite.net/ and
http://www.defenseindustrydaily.com/2005/10/us-cbo-gives-ok-to-hula-airships-for-airlift/index.php
for the wikiphobes :)

Hanging a mass driver from a string of these seems like a relatively
straightforward extrapolation of existing technology. Just put up more
of them. What's the show-stopper?

Besides which, if you've only got near-term doable technology, what
are you needing literally astronomical quantities of carbon dioxide
for? We don't have the capacity for a space industry that can use that
much stuff yet.

>> Alternately, if your heart is set on using a spacecraft of some sort,
>> how about a rotating tether? The scoops on the ends can move a lot
>> slower than orbital velocity when they dip down into the atmosphere
>> and the drives and solar panels remain out in space indefinitely.
>
>This seems to me a better concept than atmospheric mass drivers.
>Still, space tether technology is even less mature than big balloon
>and mass driver technology.

You're sending mixed messages here. :)
.

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