Re: Lunar Base Location
- From: rem642b@xxxxxxxxx (Robert Maas, see http://tinyurl.com/uh3t)
- Date: Tue, 12 Dec 2006 21:09:53 -0800
From: h...@xxxxxxxxxxxxx (Henry Spencer)
one of the major proposed processes for oxygen extraction starts
with (roughly) "(1) react hot soil with hydrogen, yielding water
vapor".
Yes, then condense the water, mix it with the concentrated sulfuric
acid you have left over from the previous batch, pass electricity
through it to yield hydrogen (to recycle) and oxygen (product),
leaving concentrated sulfuric acid again at the end. Over time, any
sulfur dioxide/trioxide (already preset or formed during heating)
or hydrogen sulfide (formed from elemental sulfur or oxide of
sulfur during hydrogen drenching) in the water vapor adds sulfuric
acid to the fluid you're working with, so you can start without any
and just let it build up over time, or you can start with a small
amount of H2SO4, just enough to make electrolysis work efficiently
with small batches of water to bootstrap your way to full size
batches later when you have extracted more sulfur from the
regolith. (You might get some chlorine from the regolith, hence a
mix of hydrochloric acid. Not a problem.)
That's the process I generally prefer/advocate.
Unfortunately, details of the Lunar Prospector hydrogen results
indicate that the hydrogen deposits mostly are *not* right on the
surface, but slightly buried. It's quite likely that digging or
drilling will be needed to reach hydrogen-containing material.
Serious exploration of the polar hydrogen resources is actually
going to be quite difficult to do with telerobotics; it's likely to
need humans on the surface.
I respectfully but strongly disagree. Consider for example this
proposal for a survey telerobot:
One tool, a 1 CM diameter ruby-crystal laser (or any laser of
similar diameter and similar or more power).
Two instruments: an infrared spectrograph for measuring any
volatile material that boils out of the abyss-material as it heats
up during passage through the hot-spot on the surface; an imaging
infrared spectrograph or at least a multi-channel infrared camera,
for measuring the blackbody temperature profile across the vicinity
of the hot spot. A really good imaging spectrograph might serve
both instrument roles, but I doubt it. We need high spectrographic
resolution but near zero spatial resolution to identify volatile
chemical composition, but decent spatial resolution and just a few
IR bands to measure blackbody temperature, so I favor two different
instruments.
Procedure: Aim laser at line-of-sight point on far side of abyss,
or anywhere else that low-power laser and/or orbiting mapping shows
a line-of-sight path from lander to a rock-face facing relatively
toward the lander. Let all mechanical vibrations damp out so the
laser aim point won't move around. Turn on laser. Surface gets to a
few hundred degrees C, causing most surface volatiles to boil off.
Continue firing laser. Surface gets to a thousand degrees C,
causing heat to conduct a few mm below surface to boil off
volatiles there. Continue firing laser. Equilibrium near five
thousand degrees C is achieved, whereby anything down several
centimeters is eventually boiled off, some diffusing sideways to
become trapped again, but some diffusing into the warm sphere and
staying within that sphere to diffuse all the way to the surface.
(Actually diffusing at an angle instead of straight outward is an
advantage, because it reaches the surface away from the hot spot,
so it doesn't completely decompose before we can measure its
molecular composition via IR spectrography.) Use IR spectrograph to
measure composition of anything boiled off as function of time (a
mix of stuff heated to 5KC and decomposed to atoms, stuff heated to
a couple hundred.C and partly decomposed into side-chains, and
stuff just barely heated past boiling point hence still nearly in
original molecular form). Look up in Earth database to learn
boiling point and loss-of-adhesion point for each such material
(directly oberseved at 100C, or inferred from set of side-chains at
several hundred C), to learn how hot the regolith had gotten where
it resided. Meanwhile, use imaging IR spectrograph or multi-channel
IR camera to measure temperature profile at surface in vicinity of
hot spot as function of time.
From surface temperature profile, compute surface thermal conductivity.
Now turn off laser, and continue to measure temperature profile at
surface in vicinity of hot spot and over hot spot itself too (since
the laser light itself won't be blinding the camera now over the
hot spot itself). This gives information about thermal inertia of
surface material and also information about heat that diffused
downward during firing of laser and is now diffusing back out after
laser was turned off.
Perform curve-fit of all the thermal-map data to generate model of
thermal conductivity and thermal inertia as function of depth below
surface. If heat comes back up in non-uniform pattern, this could
indicate lumps of material under the surface, which can be mapped
at low resolution by deconvolating the observations. But generally
the model will assume properties of material are a function of a
single variable, depth, and probably are uniform all the way from
just under the surface through the regolith until solid rock is
reached. Use that model to compute temperature profile of
under-surface material as function of depth and time. Match
boiloff-temperature of materials that were observed boiling off
against time they reached surface (shortly after they boiled off)
to compute depth they boiled off from.
Results: Profile of chemical composition and density of volatiles
as function of depth under that one hot spot. Repeat same
experiment at as many additional points as possible before all such
points exhausted or equipment stops working.
How could a human do any better? A human on Luna would either be
shaking the laser device as he holds it in his hand, ruining the
aim, or he'd be running the whole thing by local teleoperation
while sitting far enough from the laser mount that he isn't
transmitting vibrations through the regolith to the mount. Without
a human on site, the lander could repeat the experiment for months,
sampling hundreds of different hotspots all through the abyss from
a single vantage point, and then spend a week or two to move to a
different vantage point and sample a few more hundred points during
the next several months. Spirit and Opportunity traveled several
kilometers, far more than would be needed to move to several
vantage points on the edge of one deep polar-abyss. Different
landers could land at different starting points to survey other
abysses.
With a human on site, the whole study would need to be ended before
the human runs out of consumables or suffers Lunar night on that
side of the pole (too dangerous to try to circumnavigate the pole
to achieve perpetual daylight, even if an astronaut could walk that
rapidly and still have time to stop and set up laser mount several
times), like a week or two max. And the cost of one manned mission
at one location, would match the cost of ten tele-robotic missions
at ten different locations.
You be the judge which would get more data from the widest sample
of points around the insides of up to ten different abysses, maybe
first four landers two at each pole, South first then alternating,
then the remaining six at whichever pole had the best results or
has the largest number of remaining abysses not yet explored.
By the way, has somebody else already proposed a lander with
tool+instruments similar to what I proposed above and with similar
procedure and data analysis? Or am I the first?
.
- Follow-Ups:
- Re: Lunar Base Location
- From: Derek Lyons
- Re: Lunar Base Location
- References:
- Lunar Base Location
- From: Neil Fraser
- Re: Lunar Base Location
- From: Robert Maas, see http://tinyurl.com/uh3t
- Re: Lunar Base Location
- From: Henry Spencer
- Lunar Base Location
- Prev by Date: Re: Billions of dollars for nothing
- Next by Date: Re: Lunar Base Location
- Previous by thread: Re: Lunar Base Location
- Next by thread: Re: Lunar Base Location
- Index(es):
Relevant Pages
|
