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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.

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This question asks for hard science. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See the tag description for more information.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – L.Dutch Nov 20 '18 at 20:16
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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.

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  • $\begingroup$ I don't understand the stuffed shark reference :( $\endgroup$ – Ben Nov 20 '18 at 17:21
  • $\begingroup$ Do you have any references for the availability of suitable ores for molten metal batteries on the moon? $\endgroup$ – Ben Nov 20 '18 at 17:27
  • $\begingroup$ The molten-metal battery concept is very flexible. A wide range of metals are suitable. The original concept was to use aluminum. Aluminum is an element in much of the moon's rocks. $\endgroup$ – Jasper Nov 20 '18 at 17:33
  • $\begingroup$ @Ben -- It's a meme. Why have a dangerous science fiction concept with just lasers, or with just sharks, when you can "have sharks with frickin' laser beams attached to their heads!" $\endgroup$ – Jasper Nov 20 '18 at 17:37
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    $\begingroup$ en.wikipedia.org/wiki/Geology_of_the_Moon for elements $\endgroup$ – Artemijs Danilovs Nov 20 '18 at 17:50
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"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.

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  • $\begingroup$ This seems like a good start to an answer, but how can this be used to power spacecraft launched from the moon? $\endgroup$ – Ben Nov 20 '18 at 17:15
  • $\begingroup$ @Ben: in very terrifying way I'd guess. $\endgroup$ – PTwr Nov 20 '18 at 17:30
  • $\begingroup$ Or an even more terrifying way. $\endgroup$ – Skyler Nov 20 '18 at 18:47
  • $\begingroup$ @Ben Also, as per your metrics, this answer would be at the "prototyped" level. Nuclear rockets were built decades ago and were tested and shown to work but never put to use for various reasons. $\endgroup$ – Aaron Nov 20 '18 at 19:48
  • $\begingroup$ @Ben Deleted my previous question and just edited a Wikipedia link and quote into hyperion's answer. Basically just heat a gas up really hot and fling it out the back at high speed. Heating things up is something nuclear fission reactions are good at. $\endgroup$ – Aaron Nov 20 '18 at 19:55
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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.

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  • $\begingroup$ I like the idea of using resources from elsewhere in the solar system. Though not strictly to the letter of the question, it gets the spirit of it. How would the lasers be powered? $\endgroup$ – Ben Nov 20 '18 at 17:23
  • $\begingroup$ @Ben and answerer: Do note that unlike sailboats (per the analogy), a solar sail driven craft can accelerate only away from the light source. That means a solar sail spacecraft is more limited than a sailboat. A sailboat can, contrary to common sense, sail against the wind - though only at an angle against the wind up to approximately 45 degrees away from the wind, not directly into the wind at 0 degrees from it. This is not an all-stop roadblock and it could still be useful, but it does need to be part of all planning (ie: How are we going to stop when we arrive?) $\endgroup$ – Aaron Nov 20 '18 at 19:42
  • $\begingroup$ Solar sails have a thrust-to-weight ratio far less than 1. Once you get them into orbit, sure, you've got a fuel-free way to go anywhere. But what are you going to use to launch them? $\endgroup$ – Mark Nov 20 '18 at 22:16
  • $\begingroup$ How do you take off from the surface of the planet with a solar sail? This is not a hard-science answer, add more technical evidence that your plan is feasible. $\endgroup$ – kingledion Nov 20 '18 at 22:40
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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

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  • $\begingroup$ This is not a hard-science answer. See the tag on the original question. $\endgroup$ – kingledion Nov 20 '18 at 22:39
  • $\begingroup$ I believe the reference I provided does meet the minimum requirement per the tag. $\endgroup$ – Jim Nov 20 '18 at 23:20
  • $\begingroup$ It is still a link only answer. Please summarize the contents in your post. $\endgroup$ – kingledion Nov 20 '18 at 23:28
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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

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Solar power combined with ion engines and a mass driver:

Power Source

Solar power could conceivably be used to power the craft, providing both the on-board power and propulsion.

Solar power is already widely implemented, with solar panels sufficient to supply 227 Gigawats of electricity having been installed globally by 2015 (https://www.worldenergy.org/data/resources/resource/solar/).

The main component of most photovoltaic cells is silicon ( https://news.energysage.com/what-are-solar-panels-made-of-list-of-solar-pv-materials/ ). This is the second most abundant element on the lunar surface, however it exists in various ores rather than the relatively pure form used for solar panels on earth. A process to extract silicon from these ores would be required. Such a process has been suggested in this link - http://www.asi.org/adb/02/13/02/silicon-production.html .

Propulsion in space

For propulsion while in space solar panels could be combined with ion drives - this is a technology which has already been implemented - https://www.nasa.gov/centers/glenn/about/fs21grc.html . Ion drives require a propellant, for this a range of elements have been used or proposed, including xenon, argon, iodine, mercury and bismuth. Designs such as VASMIR (http://www.adastrarocket.com/aarc/VASIMR) could theoretically use practically any material for propellant. Thus it should be possible to find a suitable propellant on the moon.

propulsion to launch

Ion drives do not however provide sufficient thrust to escape lunar gravity. This could be achieved by accelerating the craft on a track using linear motors, as implemented in maglev trains on earth. There are many implementations for transportation on earth, but so far this has not been used to to propel a vehicle to lunar escape velocity. Such a launch system has been proposed for use on earth, where air resistance and a much higher escape velocity pose challenges not encountered on the moon (https://phys.org/news/2012-03-maglev-track-spacecraft-orbit.html)

Sumary

Solar panels could be used to power propulsion systems which can be run on electricity. Ion drives provide such a propulsion system for use in space, and mass drivers provide such a system for launch.

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  • $\begingroup$ Other points which would improve this answer, but which I haven't got round to include: info on the feasibility of manufacturing batteries on the moon, and info on the elements required to build an ion engine. Also, are there any usable sources of xenon, argon, iodine, mercury or bismuth on the moon? $\endgroup$ – Ben Nov 21 '18 at 21:40

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