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Our exploration of the moon requires new ideas of space transportation. This article is about Lunar Oxygen Propellant (LUNOX) and how Beamed Energy Propulsion based on LUNOX will allow us to explore full lunar surface.

The original Apollo mission focused on getting lunar rock samples, with very limited scientific program and tests performed right there. The new Constellation mission, to be conducted by NASA, anticipates longer-term scientific experiments on the moon. As a new step comparing to Apollo mission, there will be use of advanced propulsion techniques, thus cryogenic engines will replace hypergolic. In addition, separate launches of spacecraft and crew modules will be substantial departures from Apollo mission. In general, Constellation exploration program will be similar to an Antarctic expedition.

The experience of our exploration of Antarctica will serve as a role model for development of our new frontier: the moon. In this case the major limitation comes from the cost of transportation to and from our natural space satellite. Moving certain life-supporting facilities to the moon will be the key step in cutting the transportation costs. Oxygen is one of the most abundant elements of lunar soil. It can be converted into propellant for earthbound transport.

Problems of earth-based beam-propelled launch (atmospheric attenuation, vehicle drag, high gravity and high delta V) are missing or minimal in lunar environment. Lack of fuel in non-polar locations is currently a significant problem. Polar locations may find water too expensive to use for fuel and opt to use beamed energy to heat LUNOX. Use of in situ lunar oxygen extends low-cost exploration from lunar poles to the full lunar surface. This is orders-of-magnitude increase in lunar surface which can be easily explored.

When heated with beamed energy, oxygen can be used as a monopropellant. It will have storage advantage over hydrogen, while hydrogen will have much higher exhaust velocities. When heated to 4,000K, hydrogen provides an exhaust velocity of 12,000 m/s, four times faster than oxygen. BEP with oxygen will have exhaust velocities similar to modern chemical propulsion.

For the same thrust, since the beamed power is proportional to the velocity of exhaust, oxygen will need four times less power to produce same thrust as hydrogen.

Compared to earth-based beamed-energy launches, LUNOX advantage vs. hydrogen in power requirements will 24 = 6 x 4. It will be even better, if we take into account all losses of beamed energy due to earth atmosphere.

For lunar surface launch to LLO (low lunar orbit) the loaded propellant mass is slightly less than burnout mass. Due to simplicity of BEP thruster, the payload mass ratio is high and the loaded LUNOX mass is roughly equal to payload mass. Lunar Shuttle Vehicle (LSV), carrying earth return payload to Apollo-type command module, is thereby possible.

Use of LSV makes unnecessary lunar landing (and take-off) of the Lunar Excursion Module. This will reduce initial launch mass two times for lunar mission from Earth. If LSV could provide on-orbit refueling to Earth return Command Module, then the launch mass could be reduced threefold.

To summarize: Given lunar infrastructure supporting Antarctica-style exploration (fixed-base, year round deployment) with in situ resource development, LUNOX is a plentiful by-product which can be used for Beamed Energy Propulsion (BEP). BEP is favored over chemical heating due to high cost of transporting/producing fuel at the lunar site. Source power now is in 100KW to 2MW range approaching 1 mm wavelength, already capable of lunar point-to-point experiment or small payload to low lunar orbit.