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Gigabyte
2008-Nov-22, 03:49 PM
October 1, 2008 — Astrophysicists found that the moon's surface becomes electrified during each full moon.
http://www.sciencedaily.com/videos/2008/1007-preparing_for_a_walk_on_the_moon.htm


Anyone can tell when the moon is inside the magnetotail. Just look: “If the moon is full, it is inside the magnetotail,” says Stubbs. “The moon enters the magnetotail three days before it is full and takes about six days to cross and exit on the other side.”

It is during those six days that strange things can happen.

During the crossing, the moon comes in contact with a gigantic “plasma sheet” of hot charged particles trapped in the tail. The lightest and most mobile of these particles, electrons, pepper the moon’s surface and give the moon a negative charge.

On the moon’s dayside this effect is counteracted to a degree by sunlight: UV photons knock electrons back off the surface, keeping the build-up of charge at relatively low levels. But on the nightside, in the cold lunar dark, electrons accumulate and surface voltages can climb to hundreds or thousands of volts.
http://www.sciencedaily.com/releases/2008/04/080420123319.htm

NoXion
2008-Nov-22, 04:29 PM
Wow! I wonder, could this have any power applications for future Lunar colonies? Especially since the electrification seems to happen at night, particularly useful since you can't use solar panels...

PraedSt
2008-Nov-22, 07:55 PM
Cool. Maybe that explains why moon dust was so clingy. :)

cjameshuff
2008-Nov-23, 03:06 AM
Wow! I wonder, could this have any power applications for future Lunar colonies? Especially since the electrification seems to happen at night, particularly useful since you can't use solar panels...

Happens at night on the far side, which is less desirable for lunar colonies anyway due to being out of direct contact with Earth...admittedly not a showstopper if some desirable deposit is discovered on the far side.

Anyway...my gut feeling is that it would require impractical amounts of collectors to get any useful power out of it. It builds up large charges because there's little to dissipate those charges, presence of high voltages is not necessarily an indication of a large amount of available power...you are likely to accumulate a few kilovolts just getting out of bed on a dry winter morning. Given that it would also only supply power for a few days per month, I don't see it as a useful power source. You'd be better off putting the same materials to use running power cables to solar power stations on the other side of the moon.

edit: though I wonder about the effect moving through the magnetotail will have on long conductors such as those...not because of the plasma, but due to moving through the magnetic field itself.

tusenfem
2008-Nov-23, 06:32 PM
The charging of the moon is not a new topic. The interaction of the moon with the solar UV and the solar wind also creates positive charging of the sunward side and negative charging of the anti-sun side. This is the reason that the lunar dust is "levitating" as was observed by the moonwalkers.

One interesting paper is by Hapgood (http://www.ann-geophys.net/25/2037/2007/angeo-25-2037-2007.pdf) (this paper has my approval as I was referee). It does not go into the detail of the charging of the moon, but it does show some of the complications, because of the annual variation of the dipole direction, which causes the moon to go through the current sheet or not. It is a very nice read.

I hope to do some investigation on the interaction when two of the THEMIS spacecraft will change orbit to circle the moon (if this extension is allowed).

Just searching for "moon earth magnetotail" at ADS resulted in the following list (http://esoads.eso.org/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&db_key=PRE&qform=PHY&arxiv_sel=astro-ph&arxiv_sel=cond-mat&arxiv_sel=cs&arxiv_sel=gr-qc&arxiv_sel=hep-ex&arxiv_sel=hep-lat&arxiv_sel=hep-ph&arxiv_sel=hep-th&arxiv_sel=math&arxiv_sel=math-ph&arxiv_sel=nlin&arxiv_sel=nucl-ex&arxiv_sel=nucl-th&arxiv_sel=physics&arxiv_sel=quant-ph&arxiv_sel=q-bio&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=&end_mon=&end_year=&ttl_logic=OR&title=&txt_logic=AND&text=moon+earth+magnetotail&nr_to_return=200&start_nr=1&jou_pick=NO&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1).

But I don't see a real way of harnassing this electric potential for any "commercial" use. However, the moon electric field is a cause for concern for moon missions, as equipment is getting more and more sensitive to electrical discharges. (e.g. I got charged up at work, touched my laptop, and it immediately did a reset),

PraedSt
2008-Nov-24, 12:07 PM
Wow! I wonder, could this have any power applications for future Lunar colonies?

Anyway...my gut feeling is that it would require impractical amounts of collectors to get any useful power out of it.

But I don't see a real way of harnassing this electric potential for any "commercial" use.This is a request for information because my electrical knowledge is weak.

It's my understanding that electrical power comes from potential difference. In this case, the difference between the night side and the day side. If this is true, wouldn't this make it all the harder to generate power? I mean, the terminator keeps moving... :confused:

cjameshuff
2008-Nov-24, 01:36 PM
It's my understanding that electrical power comes from potential difference. In this case, the difference between the night side and the day side. If this is true, wouldn't this make it all the harder to generate power? I mean, the terminator keeps moving... :confused:

That could be handled relatively easily, actually, just switch over collectors on each line of longitude to one side or the other of a moon-wide HVDC grid. Inverter stations here on Earth do the same thing many times a second.

But rather than carpeting the moon in collectors, I think you'd be far better off storing up power to use during the night period (maybe use solar thermal, with the ground as a cold sink during the day and a hot sink during the night), connecting a few power facilities, and perhaps using nuclear for base continuous power needs.

PraedSt
2008-Nov-24, 02:48 PM
That could be handled relatively easily, actually, just switch over collectors on each line of longitude to one side or the other of a moon-wide HVDC grid. Inverter stations here on Earth do the same thing many times a second.Ah excellent. If I've understood correctly, then that is how it would work, but it would be a real pain; not because we don't know how to do it, but because it would cost too much?


But rather than carpeting the moon in collectors, I think you'd be far better off storing up power to use during the night period (maybe use solar thermal, with the ground as a cold sink during the day and a hot sink during the night), connecting a few power facilities, and perhaps using nuclear for base continuous power needs.This makes sense. I also like your magnetotail musing. You're thinking superconductors, or normal copper? :)

p.s thanks

cjameshuff
2008-Nov-24, 03:23 PM
Ah excellent. If I've understood correctly, then that is how it would work, but it would be a real pain; not because we don't know how to do it, but because it would cost too much?

I'm mostly thinking about the sheer amount of material needed. Probably enough to build a Luna-wide power grid, several more centralized power stations, and a couple colonies.



This makes sense. I also like your magnetotail musing. You're thinking superconductors, or normal copper? :)

Probably aluminum, actually. It's what we mostly use on Earth for long distance power distribution, and the moon's got a lot of it if we can figure out a good way to refine it. Copper's probably not around in any convenient ores...though a small planet's worth of near waterless geology might have some interesting surprises.

alainprice
2008-Nov-24, 06:43 PM
It's my understanding that electrical power comes from potential difference. In this case, the difference between the night side and the day side. If this is true, wouldn't this make it all the harder to generate power? I mean, the terminator keeps moving... :confused:

Just as the terminator said himself: "I'll be back"

slang
2008-Nov-25, 07:53 AM
Just as the terminator said himself: "I'll be back"

*groan*

Is the amount of energy potentially to be tapped enough to even consider tapping?

Ara Pacis
2008-Nov-25, 12:14 PM
That could be handled relatively easily, actually, just switch over collectors on each line of longitude to one side or the other of a moon-wide HVDC grid. Inverter stations here on Earth do the same thing many times a second.

But rather than carpeting the moon in collectors, I think you'd be far better off storing up power to use during the night period (maybe use solar thermal, with the ground as a cold sink during the day and a hot sink during the night), connecting a few power facilities, and perhaps using nuclear for base continuous power needs.

Dig deep enough and it's probably a constant temperature, for all your heating and cooling needs. Perhaps we'll be ableto use electromagnetic flywheels to store enough energy to survive the lunar night, until the time where a trans-lunar electrical infrastructure were necessary and desirable.

Gigabyte
2009-Oct-02, 10:06 AM
I keep thinking it was a good thing the moon missions all took place when the moon was not full.

hhEb09'1
2009-Oct-02, 01:33 PM
I keep thinking it was a good thing the moon missions all took place when the moon was not full.That was no accident, really. They wanted it light, but not heated up--so, early sunrise was optimal. That would have been near full moon for any site on the leading edge though.

Typical voltage drop for a human head-to-toe is around a hundred or two, no? Accumulators insulated from the ground can build up quite a charge.

KaiYeves
2009-Oct-02, 09:06 PM
... Shocking.

ToSeek
2009-Oct-02, 09:07 PM
That was no accident, really. They wanted it light, but not heated up--so, early sunrise was optimal.

Early sunrise was optimal for two reasons: the thermal issue, as noted, and also to put the landscape into high relief, so that the astronauts could see and avoid any problem terrain as they landed.

loglo
2009-Oct-05, 06:38 AM
I keep thinking it was a good thing the moon missions all took place when the moon was not full.

NA: That's one small ...ZAPPP! :)

Gigabyte
2009-Oct-05, 10:24 AM
I wonder if this is connected to the unusual water they found all over the surface.