THE PLAN FOR SUSTAINABLE
SPACE DEVELOPMENT
- establishing an initial infrastructure on the Moon -

PEAKS OF PERSISTENT ILLUMINATION
Because the Moon always points its face at the Earth, it rotates on its axis only once a month. For this reason, at the equators, the Moon's day lasts for two weeks and its night also lasts for two weeks. If an initial base was located near the equator it would have to have a power system such as nuclear power in order to provide the base with enough power to survive the two-week night.

Fortunately, the Moon is barely tilted compared to its orbit around the Moon. As a result, there are locations near the north and south poles where sunlight shines for greater than 90% of the time. Additionally, these locations tend to be close to certain craters where the sunlight never hits their floor. In 2009, NASA's LCROSS mission conclusively demonstrated the presence of water ice and organic chemicals in one of these permanently-shadowed craters in useful concentrations.

TRANSMITTING POWER
So, how could the power from solar panels at the Peaks of Persistent Illumination (PPIs) get down to ice-harvesting telerobots on the nearby floors of the permanently-shadowed craters? There are a number of possible solutions which people in the field have discussed. The lander could drape a wire from the crater rim to the floor while it hops between those two points. Likewise, a small rocket could lay out the wire in a one-time shot. There are plausible ways of beaming power using either microwaves or lasers. The advantage of this approach is the savings of the mass of the wire. An interesting solution which could allow for a wide separation of ice and power would be to run the lander's residual propellant through a fuel cell to produce electrical power in order to provide the telerobots their power and body heat. Once full with water, the lander could hop to the power.

HOW MUCH POWER?
If the first full-scale cargo landing was 10 metric tonnes and 2.5 tonnes of that were solar drapes and with the best specific power flown to date in space (60 W/kg) then this comes to about 100 kilowatts-electrical (kWe) of power from the get-go after taking into account losses due to support mass, conversion, and transmission. Later 20 tonne payload deliveries dedicated purely to solar power systems could deliver nearly a megawatt per mission. But even with just the initial 100 kWe of power, a XEUS-class lander could be refueled in about 44 days.