March 09, 2009
Concentrating Solar Power Needed For Moon Base

Nukes weigh too much to transport to the Moon for a extended living lunar base. Yet the nights get extremely cold. The US government wants to return to the Moon in 2020. What to do? Concentrating solar power could heat up bricks made from Moon soil and used as heat sources during long periods of darkness.

This has led some engineers to explore a live-off-the-regolith approach – taking advantage of the positive side of lunar dust: It stores heat.

Specifically, the top four inches of the regolith absorbs sunlight and heats up. Lunar explorers could harvest this material and fashion it into large bricks. Using special lenses, they could intensify the sunlight striking the bricks, heating them to temperatures far higher than they could reach with sunlight alone. Then the heated bricks could be kept insulated and used for heating habitats during the long night.

But habitats aren’t the only pieces of hardware that must be warmed. Robotic rovers and their batteries also need to survive. “We have a hard time keeping … trucks working in Siberia,” Dr. Ramachandran says. “We have no experience working at minus 150 degrees.”

The article discusses the use of reflectors on an even bigger scale to heat up areas of lunar surface where equipment would be stored. Then once night came an area would be covered with a material that reflects infrared back down toward the parked equipment.

It makes sense to wait for 10 years since by then we'll have better solar concentrators and much better batteries for storing electric power from higher efficiency solar photovoltaics panels.

Wind power has no future on the Moon.

Share |      Randall Parker, 2009 March 09 09:12 PM  Space Exploration


Comments
Allan said at March 10, 2009 2:54 PM:

Why not use a beefed up version old SNAP-10 reactor? ... I think that one produce 500 kw and that was many years ago.

Randall Parker said at March 10, 2009 6:23 PM:

Allan,

What's the weight on it?

inquire said at March 11, 2009 7:20 PM:

"The SNAP-10A reactor was designed for a power output of 30 kWt and unshielded weighed 650 lb (290 kg)."
http://en.wikipedia.org/wiki/SNAP-10A

That's pretty bulky for a mission, but if you got one installed correctly, it could serve a large base well I imagine. However, I don't understand why they don't make plans for autonomously landed, independently launched, heavy lift vehicle that simply carries cargo either into lunar parking orbit to wait for a man-assisted descent or an autonomous landing on the moon (think the ATV). This way you can put all your lift into cargo (think ARES V/Arriane V/Proton direct to a lunar orbit) and get more resources in place than necessary, all ready for construction and expansion, and then have a manned mission rendezvous with these prepared resources either in lunar orbit or on the surface.

The other option, beyond the primitive stored solar conductive heat dispersal, could possibly be one or more radioisotope thermoelectric generator (RTG, RITEG - http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator ) The advantages being light weight (they are often used to power interstellar probes) and possibly redesigned to heat water or oil to circulate through the structure as a heat source. The disadvantage being its relatively low power output, but you could possibly get several working together as the structures expanded.

Nick G said at March 12, 2009 9:58 AM:

Solar is awfully well suited for the moon. With no atmosphere,

1) it's 30% more powerful there: 1.3KW per Sq Meter.

2) concentrating solar works really well, with no atmospheric diffusion.

3) with no wind, reflectors can be extremely thin and light.

4) no clouds.

The only downside is the long night, which this article is trying to address.

Brian said at March 12, 2009 1:18 PM:

As Inquire details above, Plutonium-238 has a heat generating capacity of about 420 watts with 1kg of fuel and almost 88 year half-life (1). previous system designs (again from Inquire's second link) if you want electricity as well might be: SNAP-9A 25Welectric, 525W Heat at 12.3Kg, or SNAP-19 with 40W Electric and 13.6Kg.

If the goal is just to keep the electronics from freezing during the 48 hour night you don't need most of those parts, it's hard to beat a radioactive slug unless I'm underestimating the difficulty of shielding the semiconductors.


1) http://books.google.com/books?id=ITfaP-xY3LsC&pg=PA257&lpg=PA257&dq=radioactive+decay+heat+semiconductor+space&source=bl&ots=QiUUwAD1xI&sig=tRI_u1egP811jWM25C9_hz0x8QA&hl=en&ei=7mS5SYmMC4GEsQP0v9VI&sa=X&oi=book_result&resnum=3&ct=result

Randall Parker said at March 12, 2009 8:30 PM:

inquire,

But maybe the shielding weighs many times the weight of the reactor. I would expect concentrating solar combined with the bricks to store it would cost less weight to move it to the Moon than a reactor would. But I could be wrong.

At a location on the moon that gets dark for much longer period of time the optimal solution might be a nuclear reactor though.

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