Thursday, February 26, 2015
Mars? Why not colonize the Moon first?
When I first talk about Mars One's settlement plans with people for the first time, almost invariably the question will be asked, "Why not settle on the Moon first? It's so much closer?" It's a question that also pops up on Twitter, Facebook, and blog comments all the time. And they're right: the Moon is closer. But that is about the only thing to recommend it as a permanent settlement prospect for humans. So let's take a quick 'n' dirty look at the two sites, from a permanent-settlement persective... Water. Mars has it in the soil pretty much everywhere, to varying degrees of concentration. Mars One is looking at low-elevation areas about half-way between the equator and the north pole, on the hunch (and Viking 2 data) that the water concentrations will be highest there (but without getting into the permanently frozen polar caps which lots of water, but not so much sunlight). In these areas, evidence leads to the conclusion that the soil holds water concentrations of 3% to 18%. Luna has been shown to have 0.1% water by mass in its soil. Some permanently darkened craters near the Moon's north pole which are hypothesized to contain significant amounts of frozen water-ice. But mining this would put a settlement in inconvenient spots. And those permanently shadowed craters are among the coldest places in the solar system. Working there would not be easy. Energy. Because Mars has a day-night cycle that almost exactly matches that of Earth, Mars One plans to rely solely on solar cells to power its habitats. The only plausible alternative is to use nuclear power. There is no existing portable nuclear power plant that is light and small enough to be landed on Mars. And the Mars One people are smart enough to know that talking about launching a large nuclear power source would cause a huge outcry on Earth and face all sorts of regulatory hurdles. Both the engineering and the litigation would drive up costs considerably. Luna's day-night cycle is 28 Earth days long: each lunar day is 14 Earth days long, as is each lunar night. This makes relying solely on solar power impractical for a lunar settlement. To try to do so would require building, launching, and landing huge, heavy batteries to store sufficient power to carry the settlement through the two-week long night. So that leaves the launching and landing of a nuclear power source as the lunar settlement's only option. Good luck with that. Food. Okay, having the Earth close by does make it easier to ship food to the moon. But just ask the ISS astronauts: how satisfying is it to live on pre-packaged meals for months (or in the lunar colony's case, years)? It sure would be nice to grow most of your own food. Last year, results were published from an experiment to grow plants in simulated Martian, Lunar, and Terran soils. (Okay, the Terran soil wasn't simulated.) In a single sentence: Mars soil does pretty good (better than some of the Terran soil types); moon dirt sucks. So on the moon, you'd have to pay a lot of money just to get some good dirt. Surely there won't be a PR problem with that. Temperatures. Everyone talks about how cold Mars is. And it is cold: ranging from -180°F to -65°F in the mid-latitude, non-polar regions Mars One is looking to settle in. But that's nothing compared to Luna, where temperatures swing from -387°F at night up to 253°F during the day. Radiation. Neither the moon nor Mars have a magnetic field to ward off most of the solar and cosmic radiation coming their way. But Mars does have an atmosphere that helps reduce the radiation a bit. And being further from the sun than the moon is, the density of radiation Mars gets is less than what Luna does. Building on either place, your best bet is build or bury your habitat beneath a lot of dirt. Location, Location, Location. The moon's proximity offers only one real feature that Mars does not: the possibility of returning to Earth. A settlement on Luna would allow people to do 6- or 12-month stints there, and then return to their regular lives. Such relatively short stays on Luna should allow their hearts, muscles, and bones to return to normal after some recuperation period, just as the ISS astronauts' do. However, in my experience most people think about the (relative) closeness of the Moon in terms of being able to rescue people in the event of some emergency. But retrieving people quickly is not a realistic prospect because that requires having a very large, very expensive rocket sitting in a very large, very expensive building being maintained for months or years by a host of very expensive (but not necessarily large) technicians, just on the off chance that something goes wrong at the Lunar settlement. Even getting emergency supplies or equipment to the Moon on short notice requires having a stand-by rocket available and maintained. This sort of costly expenditure is one that neither governments nor private companies will sustain for any protracted length of time, even with human lives at risk. With Mars One, the settlers and those on Earth know from the get-go that returning or emergency supplies are impossible. No one is misled or given false hope. And the Mars One settlers are okay with that. The folks on Earth should be, too.