Vrftjkry

Background:
The moon has been selected as the base for human space exploration. Rather than ship tonnes of material out of earth's gravity well, interplanetary space-craft and space stations will be manufactured on the moons surface, and launched from there.

A level of industrial capacity allowing mining and processing ores has been developed on the moon, as well as manufacturing, and reasonably good material science using moon resources. As a rough guideline, if a material could have been manufactured on earth in the 1970s a reasonable substitute in terms of material properties can now be manufactured on the moon. If you can justify why a material exceeding that standard can be manufactured on the moon, you can use it.

Note: To clarify, the tech level does not need to be restricted to the 1970s (the target is in the future, but with minimal additional scientific advances). I have placed this restriction on the level of material science because developing simple structural materials (e.g. steel) on the moon would pose significant challenges, but the details are beyond the scope of the question.

The question:
How will these spacecraft manufactured on the moon be powered?

Criteria:

• The more realistic the power source is based on current science the better: Currently implemented > Prototyped > In development > theoretical > hypothetical > impossible


• The raw materials should be found on the moon, with as little mass as possible imported from earth. The more abundant and easily processed the raw materials are the better.


• The answer should explain how the power source is able to power both the craft's propulsion and its other power requirements.


• The end result must be a portable power source for the spacecraft, with both the drive for the spacecraft and any fuels required manufactured and produced on the moon. The same levels of credibility apply to the drive as to the power source.

Note:
I am looking for the craft's principal power source. Because some power sources lend themselves more easily to providing propulsion I feel an explanation of the propulsion system used in conjunction with the power source is also necessary.

Examples of power sources

• moon manufactured solar panels with batteries, and an electrically powered propulsion system.


• hydrogen, oxygen, and rocket engines manufactured on the moon.


• a space ready nuclear powered engine made on the moon

Excellent answers will provide: Evidence for how well developed the power source currently is. Evidence for how well developed drives which can work with that power source are. Evidence for ores of any crucial raw materials on the moon.

A brute force concept using 1970s technology and lunar materials:

Use lunar ores to make reflective materials and Stirling engines. Use these materials to build solar-thermal power plants on the moon. Store the energy using molten-metal batteries or batteries that melt-and-refreeze metals or salts, also made using lunar material.

Use high-power ablation technology for the rockets. The bottom of the ship is a large shaped piece of metal. Send an intense energy beam from the launch site to the bottom of the ship. Boil off the metal, to provide thrust. Earth-based launchers using this concept would need about 3 GW of power. (Per "Halfway to Anywhere", in A Step Farther Out.) Since the moon has about 1/6 of Earth's gravity, 500 MW would suffice.

Bonus points if the "intense energy beam" is a laser beam, mounted on a stuffed shark. (The shark skin would probably need to be imported from Earth.)

Include a small-scale solar-thermal system on the spaceship, along with a small-scale version of the battery system. Send a modest energy beam from the moon to the ship's solar-thermal system to power the spaceship.

"The Japanese Kaguya spacecraft, which was launched in 2007, detected uranium with a gamma-ray spectrometer. Scientists are using the instrument to create maps of the moon's surface composition, showing the presence of thorium, potassium, oxygen, magnesium, silicon, calcium, titanium and iron."

https://www.space.com/6904-uranium-moon.html

Thus the obvious solution is to build a nuclear fission reactor on the moon and mine for uranium. Nuclear fission (and fusion) does not require oxygen, so no atmosphere is needed on the moon.

Nuclear thermal rockets were prototyped and had (non-flight) tests from the 1950s to 1970s.

To date, no nuclear thermal rocket has flown, although the NERVA
NRX/EST and NRX/XE were built and tested with flight design
components. The highly successful U.S. Project Rover which ran from
1955 through 1972 accumulated over 17 hours of run time. The NERVA
NRX/XE, judged by SNPO to be the last "technology development" reactor
necessary before proceeding to flight prototypes, accumulated over 2
hours of run time, including 28 minutes at full power. The Russian
nuclear thermal rocket RD-0410 was also claimed by the Soviets to have
gone through a series of tests at the nuclear test site near
Semipalatinsk.

While not really a propulsant, since we as a civilisation started to explore the seas using sails, there's no reason why we wouldn't (at least at first) explore space in a similar fashion.

Enter Solar Sails:https://en.wikipedia.org/wiki/Solar_sail

Another idea would be to turn the moon in a 'laser beam hedgehog' and use powerful lasers to propel spaceships across our solar system, in a similar fashion to a solar sail.

Otherwise at current, the best conventional engine is still the Hydrogen Engine: https://www.nasa.gov/topics/technology/hydrogen/hydrogen_fuel_of_choice.html
It (liquid hydrogen), however, would have to be obtained from water from ice mined from the asteroid belt and shipped to the moon.

One propellant combination that can be sourced from the moon is powdered aluminum and oxygen. For background, see the following NASA Technical Memo:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940017287.pdf

Straying slightly from currently available technologies to those that are possible, but not yet achieved...

The Lunar surface is rich in Helium-3, so if Helium-3 fusion propulsion is developed, there is abundant fuel for it.

https://www.esa.int/Our_Activities/Preparing_for_the_Future/Space_for_Earth/Energy/Helium-3_mining_on_the_lunar_surface