SETI [Fwd: Tiny Hydrobots (pro and con) plus other subjects]


Robert Owen (rowen@technologist.com)
Wed, 22 Sep 1999 21:59:51 -0400


Larry Klaes wrote:

> >From: "Bruce Moomaw" <moomaw@jps.net>
> >To: "Icepick Europa Mailing List" <europa@klx.com>
> >Subject: Tiny Hydrobots (pro and con) plus other subjects
> >Date: Mon, 20 Sep 1999 22:13:22 -0700
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> >
> >
> > (1) There are two problems with using a swarm of tiny short-range
> >Hydrobots instead of one bigger one. First, any useful work such a vehicle
> >does will involve carrying out fairly complex analyses of organic compounds,
> >in order (at least) to distinguish biotic from nonbiotically created organic
> >compounds -- and it's highly questionable how well we could cram such
> >instruments onto a really tiny vehicle (although I'm starting to dig up Web
> >material suggesting that such instruments can already be miniaturized a lot
> >better than I previously thought). Second -- whether we're looking for
> >evidence of life on the floor of Europa's ocean or (as Chris Chyba suggests)
> >at its icy ceiling -- we're going to have to travel a considerable distance
> >to find promising spots. If we just have some tiny Hydrobots that can only
> >travel a few hundred meters, it would probably make more sense to just put
> >complex composition-analysis instruments on the Cryobot itself instead, and
> >have it carefully examine the local water itself for signs of interesting
> >compounds as it flows by.
> > (2) On the other hand, I don't think James Waldie's other
> >objection -- that a swarm of tiny Hydrobots will need a lot more total
> >weight in pressure hulls -- holds up. Instruments (especially solid-state
> >ones) aren't like human bodies; they don't need unified pressure hulls, and
> >most of the current robotic submersibles don't have them. Instead, you can
> >just embed any devices or circuits that do need pressure protection in
> >little individual blocks of pressure-resistant substances -- and the rest
> >can be protected from exposure to the water by mounting them in some
> >pressure-equalized substance (maybe an oil bath, maybe "syntactic foam" like
> >that routinely used for flotation by submersibles since 1963 -- and which
> >also makes a perfect passive-buoyancy assist without resorting to anything
> >more exotic). Such a Hydrobot can easily be chopped up into a bunch of
> >little vehicles without a serious increase in total weight.
> > On other points:
> > (3) I've contacted Robert Carlson to ask about his belief that
> >Europa's surface ice and any underlying ocean contain a high concentration
> >of sulfuric acid. He told me that the Oct. 1 issue of "Science" will
> >include his article on this, and that JPL will issue a press release on
> >it -- and on its implications for Europan life -- on Sept. 30; but he isn't
> >free to talk about it till then.
> > (4) As the ABC News piece on Gregory Hoppa's theories about the
> >origins of Europa's surface "cycloidally curved" markings was careful to
> >point out, they make strong evidence that Europa had a subsurface liquid
> >ocean earlier in its history -- but they do nothing to prove that it's had
> >such an ocean any time recently; it may have frozen (or at least frozen into
> >slush) long ago. (By the way, Carlson also points out that sulfuric acid
> >would substantially lower the freezing point of water, making it easier for
> >Europa to maintain a liquid ocean.)
> > (5) My dispute with Robert Clements over whether to power the
> >Europa Cryobot with nuclear power is turning into something resembling a
> >religious war. Let me sum up: It's not totally impossible to power the
> >Cryobot with an alternative energy source -- but any such system would be
> >hugely heavy and expensive, and that massive extra weight could be much more
> >economically used by just thickening the protective cask for a radioactive
> >supply to the point that no conceivable accident could rupture it. As for
> >the supposed panic of the Punters over this: "Cassini" had 1.5 times the
> >total amount of plutonium this mission will require, without any protective
> >cask at all -- and there was never any serious chance that political
> >pressures from environmentalists would cancel it.
> > As for a communications cable for the Cryobot: If it is necessary,
> >it is certainly a serious complication for the mission, and maybe even a
> >show-stopper -- but a low-frequency radio system may be workable as a
> >substitute. We should be looking into this.
> >
> > Bruce Moomaw
> >
> >
> >==
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======================
Robert M. Owen
Director
The Orion Institute
57 W. Morgan Street
Brevard, NC 28712-3659 USA
=======================



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