Posted by: spacewritinguy | March 19, 2008

Conservatives in Space – Chapter 5

Where to Go, What to Do

Bottom Line: There are many destinations in our solar system for human beings to attempt settlement; each of them has its advantages and challenges, but all of them can and should be tried.

Some very bright people have written excellent, full-book treatments about settling the various places in our solar system, and I encourage you to read them. The important point here is that the space economy has many possible destinations, and we would be remiss if we did not attempt to settle all of them.

Orbital Space

The area I have labeled “orbital space” might be more easily described as “the entire universe, except those parts filled by the sun, planets, asteroids, or other matter.” It is the vacuum that fills most of the universe, from here to 15 billion light years away, as far as we understand things. That is a lot of territory, filled with matter and energy we have scarcely begun to understand, much less explore or use.

We must travel through empty space to reach any other destination in the solar system. However, gravity and orbital mechanics make only particular orbits in free space attractive to space commerce and settlement. These include:

  • Low-Earth orbit (LEO), approximately 80 to 1,200 miles above the Earth’s surface.
  • Medium Earth orbits (MEO), 3,000 to 12,000 miles above Earth.
  • Geosynchronous orbit (GEO), 22,223 miles above the Earth’s equator.
  • Gravitationally stable orbits along the Moon’s Orbit, 60 degrees in front and behind the satellite, where Earth and lunar gravities cancel each other out, called Lagrange points. The three most stable of these points are:
    • L1, about two-thirds of the way from the Earth and the Moon.
    • L4, located 60° ahead of the Moon along its orbit.
    • L5, located 60° behind the Moon along its orbit.Lagrange points can be found for any two orbiting masses where a third, much smaller mass can orbit at a fixed distance from the larger masses. This includes the Sun and any of the planets.

Humanity has spent most of its time and effort in space getting people and machines into Earth orbit. Aside from sending orbiters and landers the Moon, Mars, and outer planets, most of the rest of our time has been spent literally going in circles. We have derived many benefits from those ventures, from instantaneous worldwide communications to weather observation to search and rescue, environmental monitoring, and images of the most distant parts of our universe. But we’ve only begun to tap the potential of what is possible in orbital space.

The United States and Russia each built space stations for housing human beings in orbit. The largest and most famous have been Skylab, Mir, and the International Space Station (ISS). Only ISS currently orbits our world, and it is scheduled to be completed in 2010. Because of the amount of time it has taken to assemble the station, it has been staffed by very small crews of two to three people each, which spend most of their time maintaining systems rather than performing science or developing any new technologies. When the station is completed, NASA and Russia expect to launch crews of six to seven people to ISS to begin the station’s real work.

ISS has served as a tourist destination since 2001, when Dennis Tito became its first paying passenger. Hopefully these visits will continue after the station is completed. In the meantime, entrepreneurs are planning their own orbital hotels, including Robert Bigelow, who has already launched his first inflatable space station into orbit, and hopes to send up a larger one soon. This opens up a new field of space commerce: orbital space tourism.

But beyond the government-run ISS and small-scale inflatable structures in low-Earth orbit, there is the possibility for much larger stations, spun for gravity, which could be based in the higher orbits listed earlier.

Before we even get to build settlements, there are opportunities aplenty to lay the groundwork for living and working in orbit. For instance, a lot of “space junk” has accumulated in LEO since the Space Age began. Objects ranging from flecks of paint to astronaut gloves to retired satellites are all up there, taking up space that could one day damage a future spacecraft. There could be big money in capturing, destroying, or re-orbiting this “junk.”

Solar power satellites (described in more detail in Chapter 6) could transmit solar power from orbital space down to Earth or collect it for use by vehicles or stations in orbit. Space stations in Earth and Moon orbit can act as transfer points between the home world, the Moon, and elsewhere. Captured asteroids can be mined in space, exporting their materials to space settlements or to a resource-hungry Earth, simultaneously reducing strip mining there.

Space stations in LEO, GEO, and lunar orbit could be transfer points for spacecraft traveling between Earth, Moon, Mars, and beyond. Hosting transient travelers and populations of permanent residents, these stations could operate as well-equipped spaceports, providing fueling facilities, factories, cargo storage, spacecraft “dry docks,” apartments and sleep facilities, or restaurants.

Most importantly, we can build orbital space settlements from the ground up, controlling the internal environments, to include their temperature, air purity, vegetation, and gravity. With all of the other destinations, we will have to deal with them “as is” or try to modify them. An additional advantage of a free-orbiting space settlement is that it can be moved out of the way if an asteroid or comet heads its way. Planets and moons are not so easily moved. As the technology for these orbiting cities enables the inhabitants to build self-sustaining, “closed loop” life support systems, they also can build space vehicles capable of taking very long journeys, even out of our solar system.

Of course there are disadvantages to building orbital space settlements: the exterior environment is hard vacuum, and shielding will be necessary to protect occupants from cosmic rays, solar flares, and other unfiltered radiation that would kill us, quickly or slowly, depending on the type. Also, the types of settlements I’ve mentioned-the ones with their own gravity and environments-are also much, much bigger than anything we have attempted before. Imagine building Dayton, Ohio, a city of approximately 165,000 people, in space. Obviously such a massive structure could not be built from “tuna can” segments launched by the Space Shuttle. The city will require resources from the Moon and asteroids for construction.

How do we manufacture and maintain atmosphere? How do we maintain structural integrity? We are and will learn those lessons and many others through ISS and projects like the Bigelow inflatable. In addition, Gerard K. O’Neill, a physicist from Princeton University, described in The High Frontier the methods for building “O’Neill colonies” using technologies available in 1977. If it could be envisioned with current technology 30 years ago, it can certainly be done now.

The Moon

NASA is rebuilding its capability to return to the Moon. Right now the earliest possible U.S.-government-sponsored landing on our nearest celestial neighbor is 2020. And like the ISS, the Moon base presents a potential market for commercial cargo providers. However, it begs the question: if commercial vendors can get cargo to the Moon, why not do the entire mission? The Russians, in cooperation with Space Adventures, proposed a $100 million tourist flight around the Moon by 2010. If the Russians can fly someone by the Moon, can landing them there be much farther away?

Commercially, the Moon could become a great exporter to organizations building space settlements in L4 or L5. The lunar crust is rich in aluminum and oxygen. Using an electromagnetic rail gun (also called a mass driver), miners on the Moon could launch payloads nearly anywhere in near-Earth space. Lacking much in the way of an atmosphere, the Moon could also be a place for collecting and transmitting solar power to Earth or orbital settlements.

The most common use for the far side of the Moon would be as a base for radio astronomy, where it would be blocked from the Earth’s radio noise. Given the amount of traffic beyond Earth-Lunar space anyway, the Moon could serve as an excellent base for receiving data from distant space probes, like the Deep Space Network today.

The Moon could become a net power exporter, transmitting lunar-based solar power to space or Earth itself. Or, more likely in the near future, it could export Helium-3, an isotope of helium more easily used in nuclear fusion reactions, but without as many radioactive byproducts.

Could the Moon serve as a place for commerce or settlement? Underground, most likely. Surface activities like mining or telescope maintenance could be performed spacesuited astronauts, but everything else would have to be hardened. Tourist trips across the lunar plains (or mountain-climbing expeditions by extreme sports fans) also could provide tourism dollars. The most important businesses on the Moon, however, would be those dedicated to making it self-sufficient, meaning raising plants or rabbits for food or searching for water ice in “cold traps” (permanently shadowed locations where ice hasn’t boiled away).

The Asteroids

The orbital track between Mars and Jupiter contains a wide range of rapidly orbiting rocks and chunks of metal, ranging from dust to Ceres, which is around 10 to the 7th kilograms of mass, approximately 1/6 the mass of the Moon. The rocky asteroids are just that–rocks. However carbonaceous chondrites could provide organic materials for making productive planting soil for space settlements in orbit or on the Moon or Mars. The nickel-iron asteroids also have been calculated to contain platinum-group metals, which are difficult to mine and expensive to buy on Earth. At present-day market prices, the space scientist John Lewis calculated that a single Apophis-class asteroid could have an equivalent value of $20 trillion. And there are hundreds of such asteroids whizzing about our solar system, some distressingly close to Earth.

It is very much worthwhile to visit, explore, mine, transform, and even move the objects of the asteroid belt, as some of them could cause uncalculable damage to Earth. Any mining of platinum-group metals done in space is mining not being done on Earth, which means less pollution here at home. And while we’re saving humanity, we can also make it embarrassingly rich!

Mars

Mars is the second destination listed in NASA’s “Moon, Mars, and Beyond” Vision for Space Exploration. Mars is the next logical destination because it is a world with more land area than Earth and many impressive, mysterious land features, from the solar system’s largest canyon to its tallest mountain. What’s most intriguing about Mars, however, is its potential for supporting life, in the past, now, or in the future. So far, our orbiters and landers have detected rust-colored rocks and a very thin atmosphere of carbon dioxide. Scientists are becoming increasingly convinced that the planet was once much warmer and wetter than it is now, resembling conditions that might have supported life billions of years ago. If that is so, why did it freeze up? Where did its atmosphere go? And where is its water now?

Deciphering the scientific puzzles of Mars has been the work of generations, and no doubt will continue for centuries to come. However, it is not just for scientific reasons that Mars calls to us. It also could be the home of future human settlements. The soil already possesses many of the materials necessary to support life, including water ice.

On the negative side, planetary temperatures average -50°C; its soil includes many hyper-reactive peroxides and other potential poisons; the thin atmosphere provides little shield from solar radiation; its gravity is 38 percent of Earth’s, making returns home difficult for explorers and impossible for anyone born there; and planet-wide dust storms can last for months or years, blowing super-fine particles around at speeds over 300 miles per hour.

And yet, for all that, visionary scientists and engineers and science-fiction writers have suggested ways to “terraform” Mars: that is, make it like Earth. If such a project was possible, it would require a massive industrial effort, akin to the work that went into settling and building civilization in North America, and it would be the work of centuries. Yet when it was completed, we would have a second planet for humanity to call home.

The Outer Planets

Are there reasons to head out to Jupiter, Saturn, Uranus, and Neptune? Yes! Europa, one of the Galilean Moons of Jupiter, might support life under its icy surface. Callisto and Ganymede could be made into settlements like Earth’s moon. Turbulent Io could provide sources of hydrocarbons for our plastic-hungry economy. The rest of Jupiter’s rocky moons could serve as asteroid bases or sources of metals.

Saturn’s moons are more forbidding and much farther away, but among them is Titan, a methane-covered moon with its own atmosphere, the only moon in our solar system to have one. It, too, could hold the promise of life. The rings of Saturn could provide the ultimate scenic cruise destination. And the planet’s moons, like those of Neptune and Uranus, could provide additional asteroid habitats, should we wish to build them.

But perhaps the greatest resource Uranus and Neptune could provide would be Helium-3, discussed in the Moon section earlier. While Helium-3 might exist only in traces in the lunar regolith, it is abundant in the atmospheres of the two outer giants. Rugged, giant scoop-craft would be needed to dive down and obtain this precious isotope, but once the process became commonplace, Helium-3 reactors would have all the energy they need.

The Oort Cloud

Out beyond the orbit of icy Pluto and its moons are similar objects–so many of them that if we were to include them as planets in the solar system’s list of official “planets,” grade-school astronomy would become unnecessarily complicated. Regardless of how Pluto and its neighbors are eventually classified, they consist of ice and other volatiles like ammonia, both of which will be necessary for supporting asteroid, orbital, and even planet-bound settlements. The primary business in this region would be harnessing and launching these icy proto-comets on slow, safe trajectories toward the inner planets. Given the distance from the Sun (up to one light-year), space stations would have to have highly reliable and potent energy sources, not to mention elaborate and comfortable quarters for its citizens.

Out Far, and Onward Yet

If our spacecraft and space stations can travel to and survive in the deep reaches of the Oort Cloud, they are nearly one-quarter of the way to the nearest star, Proxima Centauri. Many objects that far from Earth haven’t been detected because of their small size or dark coloration-we don’t know what else we might find on the slow march to the stars, but undoubtedly the closer we get to them, the more we will know.

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