OK, so why should our first non-Earth settlement be on Luna? Let’s look at some of the reasons (not in any particular order). This isn’t a comprehensive list so let me know if I missed something or got something wrong.
Luna is Earth’s closest neighbor. By a lot. Luna’s location comes with some significant advantages.
Travel time – As we’ve seen with Mars and asteroids, travel time means two basic things. One, longer trips expose your crew/settlers increased danger from multiple sources. Two, surviving those dangers means your mission is going to require heavier and/or more vehicles. The short travel time from LEO to the Lunar surface means we don’t have to spend as much to keep our people alive.
Logistics – Like in war, logistics have a major part in the success or failure of a frontier. The Apollo astronauts didn’t have to worry about logistics because they took everything they needed with them from Earth in one vehicle. Settlers won’t have that luxury. They’re going to need new shipments of people and resources to survive and expand. They’re eventually going to want to send stuff back to Earth. Luna will have easy launch windows to anywhere in cis-Lunar space. The launch windows for Mars and asteroids are going to be more complicated and infrequent. Luna is just going to have an easier time with logistics.
Access to markets – Luna is the centerpiece of cis-Lunar space. It’s in the name. And just as with logistics, it’s going to be easier and cheaper to move merchandise and people to and from Luna than anywhere else. The three seconds it takes radio waves to travel from Luna to Earth and back also shouldn’t impact Lunar settler’s ability to participate in Earth’s information markets. It’s not hard to image Lunar tourists once we have places for them to go and a mature transportation system.
Communications delay – In addition to quick access to Earth and cis-Lunar markets, Luna’s 3 second communication delay gives it an edge over Mars and asteroids. Telerobotics, controlling semi-autonomous robots from a distance, will be critical to making Lunar settlements (and Homesteads) a reality. Imagine Lunar settlers and robots (controlled by people living on Earth) working side-by-side. The Earth operators take care of making the robot do the work and the Lunar Homesteader fixes the robot when it breaks. This would only be possible in cis-Lunar space. The very short communication delay will also help with everyone’s morale. A three second delay is barely noticeable in a verbal conversation. A 20-minute delay would make verbal conversations nearly impossible. It’s not a deal-breaker for Mars but does add to the difficulty.
Emergency response (not a part of LH) – Lunar Homesteading doesn’t factor in returning to Earth. Other Homesteaders didn’t have an emergency parachute in case things got hairy. They didn’t have rescuers on stand-by to come get them when things were dire. They either fixed the problem, adapted to the new situation, or died. Building in any return to Earth adds complexity and cost to the plan. However, this is a priority for other concepts and missions and Luna’s proximity to Earth means that you could have some kind of rescue option. Mars and asteroid crews won’t have that kind of luxury. Think about an Apollo 13 situation but with a Mars-bound vehicle.
Lunar surface launch and landings – It takes less energy to get to/from the Lunar surface to/from anywhere else in the Solar system than it does from Earth or Mars. This is one of the primary advantages Luna has over Earth and Mars. Less energy means lower transportation costs.
Health – OK, we don’t know how Lunar gravity will affect humans. We do know that micro-gravity is bad news. However, 1/6 g isn’t the same as zero g. Some people are very pessimistic about humans surviving long-term on Luna, especially when it comes to reproduction. In 2019, the Japanese conducted the first, and only, 1/6 gravity experiment on the ISS with mice. They all came back alive. I looked but I couldn’t find anything published on this experiment yet. My point is that it could go the other way. Lunar gravity might be healthier for humans than Earth’s gravity. There’s nothing to prove that it is but there isn’t any proof that it isn’t.
Honestly, Luna doesn’t have any unique resources that we know about. Sure, Luna may have more helium-3 than Earth (we think). However, there’s no resource on Luna that can’t be found elsewhere. What Luna does have is an abundance of the stuff needed to start creating a Solar civilization.
Construction and fuel materials – Most Lunar rocks are some form of metal oxide. We will have access to large amounts of oxygen, iron, aluminum, titanium, calcium, silicon, magnesium, and other valuable elements. Homesteaders can make habitats and equipment from these materials. They can breathe Lunar oxygen. Rockets can be made that burn Lunar oxygen and Lunar aluminum. Humans can build an advanced space-based civilization using Lunar materials.
Water – Lunar ice is the current flavor of the month. Everyone wants to go there, mine it, and use it as rocket fuel. Let’s set aside the facts that we know almost nothing about Lunar ice (we don’t), how much there is (unknown), and that using it as rocket fuel is extremely short-sighted and reckless (it is). Lunar ice means that Lunar settlers may not have to bring as much hydrogen from Earth. The ice might also contain volatiles (see below), further reducing imports from Earth.
Volatiles – Here’s were Luna lets us down a bit. There just isn’t much hydrogen, nitrogen, or carbon on Luna. We need these for water, a breathable atmosphere, and to grow plants. Sure, a little bit has been deposited in the surface regolith from the solar wind (and perhaps from Earth’s atmosphere). But we’d have to move and process an awful lot of regolith to get it. Read further to find out why messing with the Lunar regolith isn’t a great idea. Luckily, Earth is nearby to take up the slack. Eventually, asteroids and the outer planets could provide for all our needs.
There you have it. We establish Lunar settlements first. Build their industrial base and learn how to thrive in our new environment. Then we expand to Mars, asteroids, and beyond!