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JohnHunt
05-14-2010, 07:27 AM
THE PROBLEM
With the same sized lunar lander we can land more mass at the lunar equator than at a lunar pole. If, for some reason, we didn't have a heavy lifter in the future but had to develop the moon using only medium-lift rockets then this difference in mass (between the equator and pole) might make a difference.

The problem is that the lunar night on the equator last for a miserably long 2 weeks. Temperatures plummet to about -180 C. At these temperatures metals can become brittle and break. Solar power wouldn't be available for lighting and heating. Batteries to keep equipment warm would have difficulty operating for the full two weeks. Some consider the lunar night to be a deal killer.

WHY THE LUNAR POLES ARE BETTER
At certain locations at the lunar poles there areas which have been termed Peaks of Eternal Light. Since the axis of the Moon is tilted only 1 degree, the sun is always moving along the horizon. Surface temperatures there are kept at about a constant -30 C. Solar panels can be raised up and power can be delivered to keep a habitat at a constant, comfy 20C.

Also, conceivably mirrors could be placed on the edges of craters to illuminate and heat areas where trapped ice water might be kept. This would help light up these dark areas and make the environments safer to work.

But again, we may want to develop and colonize along the lunar equator. So, how could one survive a two week lunar night?

SURVIVING THE LUNAR NIGHT
To start with one could construct parts of equipment that would do well at cryogenic temperatures. This is being openly discussed at the FredNet Lunar xPrize website. (http://wiki.teamfrednet.org/index.php/Tasks:Surviving_a_lunar_night)

One could use batteries to heat components but again this is challenging to do from battery reserves. Using insulation could help reduce the quantity of power needed at any given time. Equipment could be kept indoors with the settlers or in a modestly heated garage.

One of the more obvious things to do would be to dig far enough into the lunar regolith or use an existing lava tube to take advantage of the constant -35 C temperature below 1 meter below the surface. -35 C is still very cold (for people) still far better than -180 C.

Of course, nuclear power could provide significant power to help the new colonists make it through the night. On problem with this is that it may not be a solution which would make the colony self-sufficient towards being a back-up for the human race.

Also, surplus solar energy collected during the two week long lunar day could be converted into a high density form. Not sure about the efficiency, but, perhaps the surplus power could drive electrolysis to separate water and oxygen which could then be burnt during the lunar night for heat and power. Or, surplus power could accelerate flywheels from which power could be drawn during the night.

But how about people. If they couldn't safely go outdoors during the lunar night will they just sit idly by half of the time?

THINGS TO DO DURING THE LUNAR NIGHT
When you think about it, there will be plenty of indoor work to keep lunar settlers busy during the lunar night. Indeed, the vast majority of the time spent by the ISS astronauts is spent indoors. And they are kept busy.

So, here are some things that could keep them busy indoors in an insulated, heated environment.

Experiments
Gardening - Planting, harvesting (hopefully not weeding)
Setting up equipment
Maintenance and repair of equipment
Setting up and expanding housing
Industrial activities
E-mailing and video conferencing
Video conferencing with students to inspire them to pursue the sciences

Plus, part of the time would be taken up with routine activities such as sleeping, eating, meal prep, and downtime.

Rhyshaelkan
05-14-2010, 11:48 PM
One of the main goals of going into space is the building of PowerSats. One of the first test models of PowerSats could be put at EML4 or EML5 to beam power towards rectennas stationed at equatorial regions of Luna. This will allow work to continue during the long night.

Another option could be relay stations that beam power by the same methods from horizon to horizon. Due to the smaller size of Luna the relay stations would be closer than on Earth to accomplish the same. Earth horizon is 10km seen from a height of 10m.

"canopus56 wrote:

What is the visible distance from the horizon on the Moon and Earth
and for any given planet of radius R, how can this be computed? -


For any airless, spherical world of radius R, an observer at altitude h
(h << R) can see to a distance of sqrt(2Rh). Thus, for instance, the
Moon has a radius of 3,500 km, more or less. An observer at an altitude
of 10 m (that is, 0.01 km) can see to a horizon distance of

sqrt(2*3,500*0.01) = sqrt(70)

or about 8.3 km. On the Earth, atmospheric refraction extends this
distance, and per a suggestion from Andrew Young, the formula is closer
to sqrt(2.3Rh)."

Another alternative would be to use large cables to send power. Aluminum is the standard material for the transmission of power through cables on Earth due to its abundance. Aluminum is one of the major elements that comprise regolith. We could erect a similar power grid for Luna as we have on Earth. Transferring the power from the day-span side to the night-span side.

Thirdly would be the use of nuclear power for night-span.

For night-span, vehicles could use hydroxide fuel-cells. Which could be recharged with fresh hydrogen and oxygen at need. During day-span the water could be cracked again using solar power.

These are the methods we have with the tech we have. Hydroxide fuel-cells are not very efficient power-wise, but they will do the job.

In addition, we could always keep vehicles in underground garages. Just a few meters into the regolith the average temp moderates to a "balmy" 0ºC.

JohnHunt
05-19-2010, 05:59 AM
> relay stations that beam power...from horizon to horizon.

> large cables to send power

> hydroxide fuel-cells

Excellent solutions. It seems as though the lunar night is not a deal killer.

joertexas
05-19-2010, 03:29 PM
> relay stations that beam power...from horizon to horizon.

> large cables to send power

> hydroxide fuel-cells

Excellent solutions. It seems as though the lunar night is not a deal killer.

My thought was to start exteacting and cracking lunar ice in polar locations where there is sunlight all of the time. After we get the base going, then we can worry about how to extend operations further away fom the poles.

JR

JohnHunt
05-24-2010, 04:18 PM
> My thought was to start exteacting and cracking lunar ice in polar locations where there is sunlight all of the time. After we get the base going, then we can worry about how to extend operations further away fom the poles.

I would agree. The higher concentrations of water ice at the lunar poles would be an invaluable resource. Reasons to consider extending operations away from the poles are that you are able to deliver less mass to the poles than to the equator given the same size of rocket. I suspect that this is not a critical difference though. Also, permanently shadowed craters could put equipment at such low temperatures that fracturing could occur. However, there are straight forward solutions such as thermal control systems and setting up mirrors around the rims to redirect sunlight into the cold traps. Also, the lunar night on the equator becomes cold enough and I suspect that you are dealing with much of the same problem regardless of where you are.