Astrobotic is creating a prototype Ice-mining robot under contract to NASA
Buried treasure at the Moon’s poles
NASA’s Apollo crews and the Soviet Union’s robots never came close to the Moon’s polar regions where ice deposits lay hidden. Recent orbital probes from China, India, Japan and the United States have sensed that water, methane, ammonia and other volatiles are relatively abundant there. The polar deposits are key to enabling long-term settlement and development of the Moon – enabling pioneers to begin living off the land.
The initial Astrobotic robot may head for the poles to prospect for the richest concentrations of icy ores. A drill would fetch samples from up to two feet deep. A small oven would heat the samples to drive off gasses so they can be analyzed.
The Astrobotic robot will operate on solar power, since no commercial space mission has ever been authorized to carry the nuclear power sources that NASA probes sometimes use for power and heat. This means Astrobotic robots can prospect only in polar regions that are periodically illuminated by the Sun. The Moon tilts on its axis only by 1.5 degrees, compared to 23.5 degrees for Earth. This means that while polar regions on Earth have summers of near constant light and winters of unbroken night, the lunar polar regions just see the Sun clocking around the horizon, sometimes above it and sometimes below it.
Until recently, the ice deposits were thought to exist only at the bottom of deep polar craters that were never warmed by the Sun’s rays. New data from NASA’s Lunar Reconnaissance Orbiter surprised researchers with indications that ice also will be found in some south pole locations outside of craters under a thin layer of dry soil. These areas get sunlight for three to seven days a month only during the summer when the Sun is highest in the sky, so the heat dries out only the first few inches of soil.
Even more surprising, LRO data show that among nearly identical polar craters, only some show signs of ice and many others are barren. This shocking discovery called into question the main theory of why the poles have ice – that comet impacts over billions of years created thin atmospheres that eventually condensed at the frigid poles. This theory doesn’t explain why only some polar craters have ice.
In addition to prospecting, Astrobotic’s cyber-explorers will discover the best routes among the polar regions’ “peaks of persistent light.” These higher elevations receive near-constant sunlight, and thus would be great locations for human outposts needing a reliable supply of solar-generated electricity. By contrast, crews setting up shop at equatorial locations will go without sunlight for two weeks straight every month, requiring expensive energy storage solutions or the delivery of a nuclear power plant. Selecting a polar location for its persistent solar energy is similar to locating a server farm in a state with cheap electrical power.
Mining ice to support lunar colonies
The polar water, besides being essential for life support, can be split into hydrogen and oxygen for rocket propellant. Travelers can refuel their spacecraft locally for the return to Earth, cutting the cost of lunar visits in half compared to carrying the return fuel all the way from Earth. This also provides lunar outposts with their first export product. Propellant initially will be sold on site to returning spacecraft, but later it will be tankered back to Earth orbit. Here it can power space tugs that improve the economics of commercial communications satellites. These now are launched directly into the high geosynchronous orbit where they operate. If launched instead into easier-to-reach low orbits, they can be built four times heavier and four times more productive. Space tugs that get refueled by inexpensive lunar propellant can move them up to high geosynchronous orbit. Lunar fuel also can power the first human expeditions to Mars, dramatically reducing their cost. About 90 percent of a Mars mission will be fuel, so procuring it from a low-cost lunar source will be key to exploring the Red Planet.
Resources for life on Earth
The Moon may be able to supply Earth with clean carbon-free electrical power. Over billions of years, the solar wind has deposited rare isotopes on the top layer of soil, including helium3, which is an ideal fuel for fusion power plants on Earth. Helium3 is not radioactive, and when fused, does not produce radioactive byproducts. A single tanker truck could carry sufficient helium3 to provide the United States with power for a year.
Almost no fusion research funding goes into work on using helium3, in part because it’s so rare on Earth. Astrobotic prospecting robots will prove that it’s recoverable on the Moon in huge quantities, enabling an overdue shift to carbon-free pollution-free nonradioactive fusion power plants.
The Moon also may be mined for expensive rare metals in the platinum group, which are in high demand on Earth for things like automotive catalytic converters to reduce pollution. Russia and South Africa produce more than 90 percent of the world’s platinum, processing 7 to 12 tons of ore for every ounce of platinum recovered. The Moon may have richer deposits in the center of some of its many craters.
About six percent of lunar craters result from the impact of metal-rich asteroids, and some fraction of the impacts likely were at sufficiently low speeds to preserve a major portion of the asteroid for mining.
While it takes a great deal of energy to reach the Moon from Earth, the reverse direction is much less difficult. Once out of the Moon’s shallow gravity well, exports can essentially coast “down hill” to Earth, making lunar mining potentially lucrative.
Cozy locations for infrared telescopes
The floors of the Moon’s polar craters are the coldest places in the solar system, never warmed by the Sun. This makes them ideal locations for optical telescopes that work in the infrared bands below visible light: infrared detectors must be colder than the objects they’re imaging to be able to see them.
All infrared telescopes launched into space thus far have carried liquid helium to cool their detectors. When the helium supplies run out – usually in under a year – the telescopes stop working. The polar craters offer “free cold for life” for infrared observatories.
