What will the moon be used for and how big could moon bases be?
The main things that I can see as near-term uses for the moon are
1. Source of water for space operations that is many times cheaper than bringing water from the Earth. Lunar mining for water and ISRU for lunar cement. Fuel for satellites and other beyond earth orbit operations.
2. Moon as a destination for Antarctic scale science operations
3. Dark side of the moon for 100 meter or even kilometer size grand space observatories. Telescopes in a vacuum and can be made giant in one-sixth gravity and using lunar cement for structure.
4. Part of a network of facilities for expanding space operations
5. Significant Moon tourism when the cost drops toward $200,000 to $1,000,000 per person. Moon tourism cost could drop a lot when there is the SpaceX Super Heavy Starship. Other things to reduce costs are the lunar fuel and Momentus style tugs to move from low earth orbit to high earth orbit or to go to the moon. Lunar cyclers would also reduce cost while increasing the safety of going to moon. Cyclers could be large space stations with the mass for radiation protection and rotation for gravity. They would be cruise ships going to the moon and destinations of their own.
In total there could be justification and activity
Lunar Mined Water for Space Operations
A 189-page study by Philip Metzger has identified a near-term annual demand of 450 metric tons of lunar-derived propellant. 2,450 metric tons of processed lunar water could generate $2.4 billion of revenue annually.
The study was funded by United Launch Alliance so they do not mention SpaceX.
Antarctic Scale Science for the Eighth Continent
I just wrote an article for Universe Today and talked about the need to build gas stations on the moon and to have McMurdo Antarctic station scale outposts on the moon. McMurdo Station has the highest population of any Antarctic base. Antarctica and the moon are somewhat similar in size and both have tough conditions. They are mostly barren.
There are dozens of permanent and summertime bases sprinkled around the Antarctic. McMurdo has up 1,000 people in it in the summer and about 200 people year round. It had a 1.8 megawatt reactor for ten years many years ago. It was a bad reactor design and had a lot of operational issues. They now mostly use diesel.
The moon can have water produced from large amounts of lunar ice. This can be converted into fuel. It can be hydrogen and oxygen fuel or it can be the 80% weight of oxygen to go with methane brought from earth. There are areas where relatively small patches of lunar area have enough ice for 320 kilowatts of electricity to power mining operations for 1640 tons of fuel.
McMurdo has a $300 million plan to update its facilities. It normally operates with about $70 million per year in operating budget. This operating budget may not include some of the transportation, supplies and logistical support from the Navy or governmental or quasi-governmental authority. There are a couple of dozen nations with bases or sharing bases in Antarctica.
Total multinational Antarctic operations is in the range of $500 million per year now. Antartica was cutting edge continental frontier in the first half of the 20th century. The moon will be the eighth continent of science for 2020-2070. NASA does have a $21 billion budget. Global Moon science could be $2-8 billion per year.
There has been small UV-sensitive telescope on the Moon since 2013. China landed it as part of the Chang’e 3 lander.
There were studies of lunar telescopes using spinning disk of liquid with a reflective surface, lining the interior of one of the millions of bowl-shaped craters on the Moon. Such an instrument would extend for kilometers, making a gigantic “eye” to look at the universe. Liquid mirror telescopes already have been constructed on Earth.
Lunar soil could be made into lunar cement and be used as the support structure for a large telescope.
A crater could be smoothed into a telescope-shaped area to make a telescope.
The lower gravity of the moon could allow a larger structure to be made. It is better to have a telescope in vacuum than with atmosphere and the moon has no atmosphere. They would be cross between a space telescope floating in space and Earth based telescope.