Beyond: Our Future in Space

by Chris Impey

  These concepts are small precursors to any viable mining operation. Despite the costs, however, the potential returns are eye-popping, according to plausible economic models.25 In 1997, scientists estimated that a metallic asteroid a mile across contains $20 trillion of precious and industrial metals. Peter Diamandis, the X Prize guru who founded the extraterrestrial mining company Planetary Resources in 2012, has estimated that even a tiny, 100-foot-long asteroid holds as much as $50 billion worth of platinum alone. By 2020, he wants to build a fuel depot in space using water from asteroids to make liquid hydrogen and liquid oxygen for rocket fuel.

  Experts remain skeptical. There’s a huge difference between the market value of a space resource and the actual value after doing the hard work of mining the ore and bringing home the prize. As speculators have learned the hard way, cornering the market on a commodity can cause the floor on the price to collapse.

  9

  Our Next Home

  _______________________

  Stepping Stone

  Moon, Mars, and Beyond. The Moon is a hop, Mars is a skip, and the rest of the Solar System and the realm of the stars is a jump beyond. If we’re to establish a permanent presence beyond the Earth, the best place to start is the Moon.

  Almost forgotten in the more than forty years since we set foot on the Moon is the fact that NASA then had an aggressive plan for lunar exploration that would have culminated in a Moon base by 1980. Over the course of six Apollo landings, the time spent on the surface was extended from one to three days, the spacesuits were upgraded to allow moonwalks of up to seven hours, and the electric-powered rover was added to the mix. In 1968, as NASA prepared for its first piloted Apollo flight, it formed a working group to study the idea of a lunar station. After three exploratory missions to different landing sites, NASA would have sent six or more missions to a single site as preparation for a permanent base.1 The working group began its report by declaring that a twelve-astronaut International Scientific Lunar Observatory should be a major goal for the agency (Figure 36).

  Figure 36. An artist’s concept of a lunar base. Most of the raw materials needed to build and supply a habitat could be mined or extracted from the lunar soil. No new technologies are required.

  The working group’s recommended option was to develop new hardware to form the nucleus of a future base. A new Lunar Payload Module with a descent stage but no ascent stage would carry 7,000 pounds to the surface. Its heaviest item of cargo would be a one-ton shelter capable of housing two people for two weeks. It would also deposit two snazzy personal jet packs for ranging over the surface and a rover or Moon buggy that could be driven by an astronaut or by flight controllers in Houston. The payload would also have included a solar furnace to test the extraction of useful ingredients from the soil, a one-foot telescope, a bioscience package, and various pieces of lab equipment. NASA’s advisory group estimated that doing the groundwork for a lunar base would add a billion dollars to the projected cost of the Apollo program.

  It was a great idea but it ran into the buzz saw of political reality.

  NASA’s budget peaked in 1965, during the white heat of development for the Moon landings, at $5.25 billion, or 5 percent of the federal budget. President Lyndon Johnson was a staunch NASA supporter, but the cost of the Vietnam War soared to $25 billion in 1967 and Congress was looking to cut costs. After the euphoria of Neil Armstrong’s historic step, public interest waned and NASA’s budget went into sharp reverse.

  In 2009, the Center for Strategic and International Studies (CSIS) produced an estimate of the cost of a lunar base. They assume that a heavy-lift rocket will exist, and since at least three countries are likely to have such a capability, it’s a fairly safe assumption. They project development costs of $35 billion, which is much cheaper than the $110 billion price of the ISS and, if spread over a decade, is no more than the costs of flying the Space Shuttle. Base operating costs are estimated at $7.4 billion per year. Half of the operating costs come from assuming that no local resources would be available, so four tons of supplies per person per year would have to be shipped from the Earth to the Moon. Basic requirements per day per astronaut (assuming water is efficiently recycled) would be 2.5 liters (or 2.5 kg) of water for drinking and adding to food, 0.8 kg of oxygen, and 1.8 kg of dried food. The other central requirement is energy in the form of solar power.2

  Clearly, a lunar base would be more attainable if it could be as self-sufficient as possible. The Moon was always thought of as a sterile, arid, meteor-blasted rock, so there was much excitement when orbiters sent back evidence of water in the mid-1990s. In 2010, an Indian satellite found ice in the permanently shadowed regions of craters near the Moon’s North Pole. This led to research showing that the Moon contains 600 million tons of ice in nearly pure sheets several meters thick.3 The other key ingredient for a lunar base is oxygen to breathe. The lunar soil or regolith is 40 to 45 percent oxygen by mass; it’s fairly simple chemistry to heat it to 2500 Kelvin using solar power and unlock it from minerals to generate 100 grams of breathable oxygen for every kilogram of soil. Water could also be split into oxygen and hydrogen, the main components of rocket fuel.

  Even the material for a habitat could be created locally. Lunar soil is a unique blend of silica and iron-bearing minerals that can be fused into a glasslike solid using microwaves. Fairly simple technology can turn the dirt into hard ceramic bricks (Figure 37). The European Space Agency is developing a 3-D printer that can create wall blocks at three meters per hour, fast enough to build a whole habitat in a week.4

  The cost of a Moon base shrinks dramatically if air, water, and building materials can be generated locally. All of the technologies needed to do it have been demonstrated in the lab. There’s no projection or wishful thinking of the kind invoked for space elevators, for example.

  Figure 37. Cutaway view of a lunar base, based on an inflatable dome and a 3-D printing concept. After assembly, the inflated dome is covered with a layer of 3-D–printed lunar regolith to protect the occupants from radiation and meteorites.

  Location, location, location. It’s as crucial when buying a home as when planning a Moon base. The best spots are high mountains on the rims of large craters near the poles. They would be close to abundant water ice but high enough to be peaks of eternal light, always illuminated by the Sun so with access to solar energy all the time. At low latitudes, colonists would have to contend with extreme temperature variations, plus the 354-hour-long lunar night. But they could make use of one of the tunnels formed long ago when basaltic lava flowed on the Moon. The lava tubes can be as wide as 300 meters. They maintain a stable temperature of –20°C as well as provide protection from cosmic rays and meteorites.5

  A Moon base would be most valuable as a waypoint between Earth and Mars, and points far beyond. The Moon’s low gravity and slow rotation mean that a space elevator could be built with materials already available. The honeycomb fiber called M5 is lighter and stronger than Kevlar; a ribbon 3 centimeters wide and 0.02 millimeter thick could support 2,000 kilograms on the lunar surface or 100 climbers with a mass of 600 kilos each, evenly spaced along the ribbon. We could build a lunar elevator right now.6 The $35 billion development cost mentioned earlier does not assume a space elevator; it would reduce this cost by 20 to 30 percent.

  Bill Stone, whom we met earlier with his plans to detect life on Europa, has formed the Shackleton Energy Company to prototype technology to separate lunar water into hydrogen and oxygen for rocket fuel. He knows that producing the fuel on the Moon will slash the cost of going elsewhere in the Solar System. To man his base, he won’t be looking for typical NASA hires; he wants people with the spirit of wildcatters. To get back home, the first crew will need to produce the fuel for their journey.

  With all this potential, it’s safe to predict that the long hiatus in lunar exploration is over. In early 2014, China’s Jade Rabbit rover arrived at the Bay of Rainbows in the northern part of the Mare Imbrium, or Sea of Rains. The private sect
or is showing interest. The Google Lunar XPrize was announced in 2007, with a $30 million grand prize to any team that lands a robot on the Moon and sends it 500 meters across the surface while sending back high-definition images and video. Eighteen teams are still in the running, and several might reach the Moon before the deadline of December 31, 2015.7 India and Japan have plans for a lunar base by 2030; while Europe and the United States are currently dithering, they may collaborate on a base with a similar time frame.

  Meanwhile, the space miners have their eyes on helium-3, an isotope of helium that’s a key ingredient in a viable fusion power reactor. Helium-3 is extremely rare on Earth but more abundant in the lunar soil, where it’s been generated over billions of years by the solar wind.8 The idea is that fusion is the future of energy generation when coal, gas, and oil start running out, as they will around midcentury.9 Fusion is a clean form of energy that leaves no radiative waste and has a high energy yield per kilogram of fuel. But fusion is extremely challenging. Europe and the United States each have been investing about $1 billion per year, with no energy-producing reaction sustained for more than a fraction of a second.

  Most fusion research involves two isotopes of hydrogen: deuterium and tritium. The technical challenge is to contain the reaction, which takes place at a temperature of millions of degrees, far above the melting point of any known material. Helium-3 fusion requires even higher temperatures, but it has the advantage of generating most of the reaction energy in the form of charged particles, whose energy can readily be harnessed. The levelheaded view is that the Moon isn’t going to rescue us from energy profligacy. Helium-3 presents three unproven realms of technology: harvesting it from the Moon, transporting it back to the Earth, and using it in a fusion reaction.

  If we go back to the Moon, it will be for the more prosaic reason that it’s the easiest and closest place to go to learn how to live off-Earth. American apathy might change if another country starts to colonize the Moon, and, as we’ve seen, the Chinese are thinking long term and making substantial investments in space projects. Early in 2014, the People’s Daily quoted Zhang Yuhua, deputy general director of the Chang’e 3 lunar mission, as saying, “After the future establishment of the lunar base, we will conduct energy reconnaissance on the Moon, set up industrial and agriculture production bases, and make use of the vacuum environment to produce medicines.”10

  She closed by saying, “I believe that in 100 years, humans will actually be able to live on another planet.”

  The Lure of Mars

  What happened to the Mars of our imagination?

  The red planet used to be ominous and threatening. Babylonian astronomers took note of Mars, with its reddish color and its strange, episodic backward motion on the sky. They called it Nergal, god of the underworld and bringer of plague, epidemics, and disaster. The ancient Greeks associated Mars with Ares, one of the twelve Olympians and a son of Zeus and Hera. Ares was a violent and spiteful god who enjoyed combat; his sister Athene called him “a thing of rage, made of evil, a two-faced liar.” The Greeks refused to honor him and no sacred places were built in his name. He was remembered on the battlefield, where his companions were Deimos and Phobos, the gods of terror and fear. His reputation softened slightly with the Romans, who made him the god of agriculture as well as war.

  The Dutch astronomer Christiaan Huygens drew the first map of Mars in 1659; in a posthumous book titled Cosmotheoros, he speculated that the bright spots on Mars were evidence of water and ice. He also thought that intelligent life could exist there. A century later, William Herschel demonstrated that Mars had seasons like Earth’s and argued that ice at the poles could support life. In the mid-nineteenth century, when large telescopes produced sharper images of Mars, some astronomers thought that the dark colorations might be due to vegetation and the striations or streaks on the planet might be artificial constructions.

  Percival Lowell had no doubts at all. The Boston merchant and keen amateur astronomer used his fortune to build a new telescope at a pristine, dark site in northern Arizona. He was racing to complete the telescope in time for a particularly close approach of Mars in 1894. Lowell convinced himself that the features he saw on Mars were canals, where a dying civilization was trying to bring water from the poles to the equatorial regions. He wrote several sensational books to support his claims. A few years later, H. G. Wells used aspects of Lowell’s work in his science fiction novel The War of the Worlds. It was an instant classic.

  Once again Mars was portrayed as malevolent: “. . . across the gulf of space, intellects vast and cool and unsympathetic, regarded our planet with envious eyes, and slowly and surely drew their plans against us.”11

  In the early twentieth century, the scientific and pop-culture views of Mars diverged. Edgar Rice Burroughs wrote A Princess of Mars as a serial in 1912 and as a book five years later. Civil War veteran John Carter mysteriously finds himself on Mars, a world populated with four-armed aliens, wild monsters, and scantily clad princesses. Carter uses weak gravity to exercise superhero powers and gets the girl in the end. Burroughs wrote ten more Mars stories, and his lurid fantasies inspired Arthur C. Clarke and Ray Bradbury to launch a grand tradition of Mars science fiction. In 1938, Orson Welles revisited The War of the Worlds with a radio show. His realistic live broadcast scared tens of thousands of people in the greater New York area; many raced from their homes at the prospect of a Martian invasion.

  Meanwhile, Alfred Russel Wallace, codiscoverer of natural selection, had rebutted Percival Lowell, insisting that a freezing Mars could never support liquid water. This argument got stronger with remote sensing in the middle of the twentieth century. Mars fever finally cooled in 1965, when Mariner 4 swooped within 10,000 kilometers of the planet’s surface and saw an arid, crater-pocked terrain with no signs of life. The twin Viking landers cemented this picture in 1976.

  Since then, however, the pendulum has swung back toward the middle. Mars can’t host liquid water on the surface; a cup of water on the surface would evaporate in seconds because the typical temperature is –60°C. It would evaporate rather than freeze because the atmosphere is so thin, very close to vacuum. The topsoil can’t host life because the thin atmosphere allows it to be blasted by micrometeorites and sterilized by ultraviolet radiation and cosmic rays. But orbiters have provided abundant evidence of erosion and river deltas and shallow seas in the past. Craters overlying these features suggest that three billion years ago Mars was warmer and wetter and had a thicker atmosphere. A series of intrepid rovers—the Tonka Toy–size Sojourner in 1997, the go-kart–size twins Spirit and Opportunity starting in 1993, and the SUV-size Curiosity more recently—have painted this picture in more detail. These rovers have collected rock samples that can only have formed in the presence of water.12

  Astronauts on Mars wouldn’t find water on the surface but they’d be able to gather all they needed by a careful choice of landing site. Spectroscopy from orbiting spacecraft reveals extensive ice at high latitudes, hidden by a veneer of dust and rock. If melted, and if there was a protective atmosphere, it would cover the planet with a puddle deep enough to get your ankles wet. There’s also evidence of gullies, with channels carved by water that erupts episodically from aquifers under the surface, where water can be kept liquid by pressure from above and radioactive heating from below (Figure 38). Scientists debate how deep colonists would have to drill to hit water, but it might be as little as 10 or 20 meters.13

  While it’s not the Mars of anthropomorphized aliens or comic-book superheroes, it’s a planet that could host microbial life right now, as well as in the past. The red planet is far more habitable than the Moon because of the atmosphere, the higher temperature, and the amount of subsurface water. It beckons us to visit, and perhaps stay.

  Figure 38. The sharp V-shaped gullies on this escarpment on Mars are strong evidence of liquid water runoff. The water is likely to have seeped out of the escarpment about a third of the way down from the top, where it can be kept liquid
by pressure in aquifers.

  Establishing a Colony

  Robert Zubrin never lost the faith. With a PhD in nuclear engineering and more than 200 technical papers to his credit, Zubrin has been a staunch advocate of human exploration of Mars for thirty years. He holds patents for hybrid rocket planes, synthetic-fuel manufacturing, magnetic sails, saltwater nuclear reactors, and three-person chess, but his true passion is Mars. He thinks we can lower the cost and complexity of a Mars mission by “living off the land,” or utilizing as many resources as possible from the air and soil. His ideas were strong enough to be adopted by NASA as their “design reference mission,” but he became frustrated at NASA’s glacial progress and anemic government support, so he founded the advocacy group Mars Society in 1998. He’s written a series of books that make the case for going to Mars.14

  Asked about saving costs with a one-way journey, Zubrin has said: “Life is a one-way trip, and one way to spend it is by going to Mars and starting a new branch of human civilization there.”15

  Mars is a challenging goal for human exploration. The problem isn’t energy. The energy cost of going to Mars is less than 10 percent more than the energy cost of going to the Moon. The problem is the distance. An energy-efficient trajectory involves a travel time of nine months each way. The trip can be shortened to six or seven months at the expense of extra energy—a far cry from the week it takes to get to the Moon. The cost of transporting two years’ worth of supplies for even a small crew is daunting. Wernher von Braun was the first to make a technical study of a Mars mission in the 1950s, but it was hopelessly grandiose, using a thousand Saturn V rockets to build a fleet of ten spacecraft in Earth orbit to then carry seventy astronauts to Mars. He pitched a scaled-down concept to President Richard Nixon, but it was passed over in favor of the Space Shuttle. Former NASA administrator Thomas Paine tried next. Perhaps he’d watched too much Star Trek, but he aimed to conquer and industrialize the Moon with nuclear space tugs, launch a fleet of space stations into Earth orbit, and send several dozen spaceships a year to Mars to build a space station and support the colony. The Reagan administration was happy to shelve his report.