Lunar Harvest

January 15, 2009

When I tell friends and students of NASA’s plans to return humans to the Moon (yes, Virginia, we really did land on the moon!) I typically get yawns. It’s sort of “been there, done that” -- why go back?

Given today’s economic, political, and environmental concerns, I worry that moon exploration will seem irrelevant and extravagant. There’s a nagging sense of “déjà vu all over again” because the Apollo missions of the late 1960s to early 1970s became irrelevant in the shadow of the Vietnam War, environmentalism, and White House scandal.

However, China’s plans to send humans to the moon will keep the U.S. active and diligent in perusing manned lunar exploration, to offset fears of space militarization.

Not to paraphrase Obi Wan Kenobi, but it is our destiny to become an extraterrestrial civilization. By definition, that is a civilization which exploits the vast resources of the solar system for industrialization and colonization.

We have a unique asset for taking our first baby steps: the moon. At only 240,000 miles away it is only a three-day journey by rocket –- vastly shorter in time than the pioneers took to travel to the West Coast.

Once on the moon, we can  harvest interplanetary resources. What resources? Certainly not coal, oil, gold or diamonds! The moon has something vastly more valuable than gold... raw materials, and even fuel, for the next generation of power plants to serve an energy-hungry planet.

The prospects for finding lunar resources and mining them are explored in the Discovery Channel’s program “Mining the Moon,” part of its Sci-Trek series.

The ultimate answer to our energy crisis is in fact to two-pronged, and the moon offers solutions for both.

First, an array of huge solar power stations could be built to orbit Earth and beam electricity to ground station via microwaves. This requires no breakthrough physics, just mega-scale space engineering.

It would require much less energy to mine the construction materials from the moon and launch them into space from there, as compared to getting construction materials out of Earth’s deep gravitational well. The moon is rich in the necessary elements including titanium and iron oxides. As I previously blogged about, the lunar soil makes an excellent ceramic material when mixed with epoxy.

Another energy solution requiring no breakthrough physics is nuclear fusion, aka duplicating the energy processes of the sun. Experimental fusion reactors are being developed. This requires generating and controlling million-degree plasma inside powerful magnetic fields or laser beams. The first commercial self-sustaining fusion reactors, however, are still decades away by all estimates.

Fusion is often confused with nuclear fission, which we use in power plants today to extract heat from the decay of radioactive elements. Nuclear fusion extracts energy from combining lighter elements. The special ingredient needed for a power plant is helium-3 (our Macy Thanksgiving Day Parade balloons are filled with helium-4 -- so we can't mine those). As an isotope (aka missing one neutron), helium-3 readily combines with another isotope of hydrogen, called deuterium, in a fusion reaction.

About 25 tons of helium-3 -- enough to fill a single railroad boxcar -- would provide electrical power to the United States for one year at our current rate of energy consumption. And, there is virtually no radioactive waste or other byproduct. Fusion is God’s chosen form of energy.

But helium-3 is very hard to find. God doesn’t make much helium anymore (it was cooked up in the Big Bang) -- except in the fusion engines of stars.

Helium-3 atoms produced inside the sun ride the solar wind and embed in the upper few feet of regolith on the moon.  It’s estimated that a million tons of helium-3 have been deposited on the moon. In principle, automated mining equipment could skim the surface regolith and haul loads back to a lunar processing plant for helium-3 extraction.

For this to be economically viable, it would require a robust infrastructure of human bases with manufacturing, transportation and repair facilities. But for humans to live off Earth, life-sustaining oxygen and water must be harvested on the moon as well.

Fortunately, that too can be mined on the moon. Oxygen is chemically locked up in the regolith, and water ice from comet impacts lays buried in the bottom of perpetually dark craters near the poles.

There are lots of Buck Rogers illustrations and animations of humans doing routine chores on the moon. But in reality the lunar regolith is nasty stuff. Finer than talcum powder, and charcoal black, it would easily clog up machinery. When breathed it could cause silicosis and other lung diseases common to coal miners. In fact, the snow-white spacesuits of the Apollo astronauts quickly turn black with dust, making them look like lunar coal miners. So, commercially mining the moon will be technologically daunting, but not impossible.

The thought of strip-mining the moon will lead some nature movement zealots to protest that we are defacing a romantic astronomical body. But, better it be the moon than Earth. Think of Earth as the only passenger car in a freight train of coal cars, which are the resources offered by the moon, asteroids, and comets.

Industrializing the moon won’t be easy, and it will keep us busy for decades. But if we don’t learn to harvest resources in the solar system, we are doomed to turn mother Earth into a cesspool.

Comments

[rodelyn]

this is very interesting information

[Adam]

Hi Ray

Nuclear fusion, ITER style, will use deuterium-tritium not helium-3. Good thing too because otherwise there'd be no way of extracting power - 80% of the energy is released as kinetic energy of the neutrons, and neutrons escape the plasma confinement. They'll be soaked up by a lithium jacket surrounding the plasma chamber, doing double duty breeding more tritium and heating the lithium for useable heat. Currently there's no tokamak fusion reactor design that can fuse He3 and deuterium.

A Bussard fusion reactor might be able to do it, but it's a configuration that is yet to hit breakeven - unlike tokamaks. I believe advanced fusion fuels are the way ahead, but presently we don't have the reactor designs to fuse them. The Moon has a lot of thorium - if it could be gotten back to Earth cheap enough then it might be worth mining. Imagine teleoperated prospector rovers mining the thorium and a Jerome Pearson style lunar space-elevator lifting it to L1 for pick-up.

[x-ray fluorescence]

Good informative post.Good thing is there'd be no way of extracting power - 80% of the energy is released as kinetic energy of the neutrons, and neutrons escape the plasma confinement in the nuclear fusion..