The Trump administration has said America should return to the Moon and build permanent bases. Robert Zubrin points out (in an article at New Atlantis) that this stated goal has not received any meaningful funding. The New Atlantis article by Robert Zubrin has an updated write up of his Moon Direct program proposal.

The Lunar Orbital Platform-Gateway (formerly known as the Deep Space Gateway) is receiving some money. The gatewate will be a waste.

The gateway is a planned space station that will orbit the Moon, supposedly serving as an outpost for human explorations to the Moon, Mars, and deep space.

NASA says Orion would take its first crew around the Moon by 2023. Vice President Pence has recently stated a goal of putting astronauts on the gateway by the end of 2024.

The lunar gateway idea is silly. There is no need to have a space station circling the Moon in order to go to the Moon or Mars or anywhere else. And there is not much research worth doing in lunar orbit that can’t already be done on the International Space Station, in Earth orbit, or with lunar probes and robots.

NASA claims the gateway would create an opportunity
* to test state-of-the-art propulsion, communication, and other technologies at a greater distance from Earth
* tele-operated rovers could be sent from the gateway to the Moon
* planets and stars could be observed from a different vantage than from the ISS or current telescopes.

None of these activities requires human presence in lunar orbit. These are not reasons for having a gateway, but rationalizations.

We don’t need a space station in lunar orbit — but we could use a base on the Moon itself. A Moon base would be much more than a stopping point; it could also be a site for producing hydrogen–oxygen rocket propellant from water on the Moon. This is a powerful propellant that has been a mainstay of rockets for decades, used by the Saturn V and the space shuttle.

Some areas on the moon have water ice concentrations of 30 percent by weight in the topmost layer of soil.

PNAS – Direct evidence of surface exposed water ice in the lunar polar regions

The moon is a world with a surface area larger than the continent of Africa. Its terrain is rough, roadless, and riverless, so astronauts cannot effectively explore it using surface vehicles. Lunar explorers are going to need to fly.

It is theoretically possible that multitudes of locations on the Moon could be visited by launching scores of missions directly from Earth, the cost of doing this would be astronomical. We need to create a base that can produce propellant on the Moon. Moon missions need to fueled and operated on the moon. Only occasional missions from Earth are needed to resupply consumables and switch out crews.

Where should such a base be located? The Moon’s poles are ideal not only because they have nearby permanently shadowed craters with water, but because they also feature near-permanently illuminated highlands offering reliable access to solar energy. The poles are thus the clear favorites for a base, as they provide both the raw material and the energy source necessary to manufacture hydrogen–oxygen rocket propellant.

Producing water and fuel on the moon

First we will consider propellant production. Each Moon Direct mission requires 6 metric tons of propellant to be made on the Moon for the LEV’s flight back to Earth orbit. It also requires 6 tons of propellant for each long-distance surface sortie from the base to a distant location on the Moon and back. For purposes of analysis, we will assume that once the base is operational, every fourth month there will be a round-trip mission from the Moon to Earth to exchange crew, and in each other month there will be one long-range exploration flight. The propellant manufacturing requirement will therefore be 6 tons per month, or 200 kilograms per day.

Engines running on liquid hydrogen and liquid oxygen use a higher ratio of hydrogen to oxygen than what is found in water. To get our 200 kilograms of propellant, we would need to electrolyze around 260 kilograms of water (about 70 gallons) per day. The happy side effect is that this would leave about 60 kg of leftover oxygen every day, which could be used for crew breathing supply.

The dominant power requirement will be for vaporizing and electrolyzing the water. To electrolyze 260 kg of water per day will require 56 kilowatts of power. We can estimate that water could be vaporized at the same rate using beamed microwaves with about 26 kilowatts of power. Cryogenic liquefaction of the hydrogen and oxygen products — aided by the extremely cold temperatures on the Moon — will add about 25 kilowatts, and life support and other equipment will also add another 13 kilowatts to the power needs, so we can estimate 120 kilowatts for our total power requirement. This could be supplied by either a solar array or a nuclear reactor; for either alternative we estimate a mass of around 4 tons using proposed technologies.

Moon Direct

Moon Direct requires relatively little launch mass and largely uses existing technologies.

Following our assumption that launch costs and non-launch costs will be roughly equal, we could execute our setup missions (two flights for Phase 1 and two Phase 2 missions) for about $1.5 billion. Recurring missions will cost $420 million per year. This is two percent of NASA’s current budget. This is very inexpensive by the standards of human space programs. FNASA’s human spaceflight program total budget is currently around $10 billion per year with little clear purpose.

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