THE SOUTHWORTH PLANETARIUM
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70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 2458876.16
2019-2020: XCIII
"Sweater: garment worn by a child when its mother is
feeling chilly."
-Ambrose Bierce
THE DAILY ASTRONOMER
Tuesday, January 28, 2020
Moon Water?
Last week we tried to discourage one of the subscribers from escaping to a
nearby nebula in order to escape relatives and creditors. This week,
another subscriber who aspires to one day live on the moon, asked a
question about the lunar water resources. He believed that the moon
couldn't possibly retain any water resources because of its searing heat
and low gravity.
*"Hello! I read your article about going to the Helix Nebula. I was
thinking I could get away from everyone simply by moving to the moon. As
I was reading about the moon, I saw where there are water reserves on it.
How is that even possible? Isn't the day time temperature above 200
degrees and isn't its gravity weak? The water should have vaporized long
ago and escaped into outer space. Besides, how could it even get water in
the first place?" -Displaced Marvin*
The notion of moon water has always encouraged aspiring lunar colonists who
have realized that living on the moon necessitates the conveyance of
EVERYTHING humans need to sustain life: food, water, oxygen, et cetera.
The cost of transporting such necessities for even a quaint lunar village
would prove prohibitive. How much more convenient and cost effective
would it be if water were already present. Not only could it be used as
water, but it could also be used to extract oxygen: two vital necessities
from a single resource.
While the existence of lunar water (as opposed to moon water, a delectable
treat for the discerning Pagan) has been discussed for years, recent
explorations, notably by the Lunar Reconnaissance Orbiter, have discovered
evidence consistent with the presence of water in the south polar region.
That's the rub. Some parts of a southern polar crater could be
perpetually steeped in shadow. In such a dark area, temperatures would
remain well below zero and any water would be trapped as ice. (Any ice
on the moon's lit region would rapidly vaporize and the water's constituent
molecules would escape.)
Water could be delivered to the moon (and other places in the solar system)
by comets, generally believed to be composed of water. These impacts
have likely happened repeatedly during the moon's long lifetime. Most of
the water these impacts delivered has long since dissipated as they
occurred in lunar regions exposed to sunlight. Only water derived from
comets that struck the shadowed lunar regions could still remain on the
moon's surface.
An important issue pertaining to moon water relates to the form it
assumes. Could it be gathered in large chunks, like glaciers, or would it
be distributed over wide regions, like a thin coating of frost? Lunar
colonists would prefer the first option, as the water would be localized
and therefore readily accessible.
In 2022, NASA aims to deploy VIPER , the Volatiles Investigating Polar
Exploration Rover, to the moon to map its water reserves. Apart from its
array of on-board scientific instruments, VIPER will also drill into the
lunar surface in search of water reserves.
When you feel to the moon, you might discover great reserves water, albeit
frozen solid at temperatures averaging -200 degrees F. Still, that puts
you in a better position than the person who might still be contemplating
self-exile in the Helix Nebula
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