Sunday, May 5, 2013

Beyond Earth's Atmosphere: Energy Needs For Space Colonization

Beyond Earth's Atmosphere: Energy Needs For Space Colonization:

Beyond Earth's Atmosphere: Energy Needs For Space Colonization
Beyond Earth's Atmosphere: Energy Needs For Space Colonization
Conceptual view of a space elevator using a 22,000 mile-long cable held by an asteriod counterweight in geosynchronous orbit (click on the Chapter 9 link below). This is amazingly doable for such a bizarre concept. From Hoagland (2005) with permission.
We are going to return to the Moon. No question. And long-term human settlement will follow at some point, mainly to development mineral and energy resources available on the Moon, but also to emplace protective systems aimed at avoiding large asteroid impacts of the type we were all recently made aware with that grazing meteor strike in Chelyabinsk and the simultaneous near-miss by big-rock DA14.
Growing shortages of key inorganic elements, such as rare earth elements for all our electronic gadgets and renewable energy systems, platinum and other related metals, and even helium for medical equipment (yes, and balloons!), suggest that we may need more non-renwable resources than Earth can provide (He shortage; REE shortage).
So it is with perfect timing that a long-awaited Special Publication from the Energy Minerals Division of the American Association of Petroleum Geologists has been published.  And it has to do with outer space – AAPG Memoir 101: Energy Resources for Human Settlement in the Solar System and Earth’s Future in Space (full disclosure, I am an author on one of the chapters).
Off-world settlements will provide fuel and life support materials for space missions and planetary operations, and for return of goods to Earth. In the U.S., such dreams are being pursued by entrepreneurs and private entities working both independently and with NASA (Elon Musk is the best example of that). In other countries, they are still nationalized, but the industry will eventually emerge on its own.
Energy resources that can be harvested in space for the benefit of Earth include helium-3 that occurs in abundance on both the Moon and asteroids and is ideal for new small fusion plants, as well as solar energy that can be collected and transmitted in concentrated form to Earth.
Hydrocarbons, helium, hydrogen, and volatiles in the solar system are important for human exploration and habitation because they will provide essential high-energy, high-density fuels and feedstock for off-world manufactured goods and materials for construction.
Metals, platinum-group elements, rare earth elements, and other volatiles, like H, H2O, and carbon compounds, are abundant on asteroids, many of which are relatively accessible from Earth. We could even use the asteroids that come too close as a way to remove them as dangers since we’re going to have to deal with them anyway.
Lest you think this is science fiction and that no one would ever fund this from a business standpoint, consider the Class M asteroid pictured below. Class M asteroids are chunks of old planetary cores left over from the Late heavy Bombardment period in the Solar System’s early days when the thousands of small planets that were accreting fought it out for who would survive the orbiting slugfest (Space Invaders).
Class M asteroids are composed of iron with large amounts of nickel, cobalt, and platinum group metals. The asteroid 3554 Amun-NEA pictured here is about 1.3 mi (~2 km) in diameter, similar in size to typical metallic ore bodies on Earth. Its ore zone mass is about 30 billion tons, and with 20 oz/ton of nickel, contains almost 17 million tons of nickel alone (34 billion pounds) and is worth US$600 billion in today’s market.
Beyond Earth's Atmosphere: Energy Needs For Space Colonization
Beyond Earth's Atmosphere: Energy Needs For Space Colonization
A small class M asteroid named 3554 Amun-NEA containing over 17 million tons of nickel, about $600 billion in today’s market. Similarly for cobalt and platinum group elements (click on the Chapter 9 link below). Courtesy of William Ambrose and Astronaut Jack Schmitt.
Together with the need to protect sensitive environments on Earth from mining operations, this will eventually become a reasonable alternative to digging up the Earth to extract every last ounce of precious metal in our own crust.
Memoir 101 is an integrated review of energy resources in the Solar System and of technologies that can be used to implement them, like the Space Elevator, megasolar reflectors, or the lunar He-3 nuclear reactor.
Solar energy presents a good example of how systems in space differ from the same ones on Earth. One of the chapters offers a case for developing space-based solar energy from a lunar array. Although the Earth intercepts 175,000 terawatts (TW) of solar power continually, it is impractical and costly to gather high-yield solar power on Earth because of adsorption from the atmosphere and reflection from clouds back to space. Even the biosphere captures only a small fraction (<0.03%) in the form of atmospheric carbon and the oxygen separated from water.
Currently, a stand-alone solar array on Earth provides an average energy output of 3W per square meter (W/m2) of ground area. Earthbound power storage, conversion systems, and long-distance transmission lines greatly decrease the effective output of solar cells or concentrators. For example, 20 TW of Earth-based electric power requires approximately 2.7 million square miles (7 million km2) of collector area, representing approximately 5% of the landmass of Earth. This is unlikely to change in this century.
On the Moon, which has no atmosphere, a lunar solar-power (LSP) system can capture hundreds of times the energy per area than on Earth. An LSP system can economically gather solar power and convert it into streams of electromagnetic waves that are designed to dependably and safely deliver power efficiently to inexpensive receivers (rectennas) on Earth when power is needed.
Operating at 2.5 GHz to pass through Earth’s clouds and atmosphere, 20 TW from lunar-based electric power requires only 40,000 square miles (100,000 km2) of rectenna area on Earth. Moreover, materials for the collection of solar energy can be manufactured in situ on the Moon for less than on Earth. The economics are weirdly advantageous, even with technologies existing today, and can be bootstrapped without huge initial costs. The environmental savings to the Earth cannot be overstated.
Beyond Earth's Atmosphere: Energy Needs For Space Colonization
Beyond Earth's Atmosphere: Energy Needs For Space Colonization
Concept of a nuclear-powered robotic gravity tractor moving an asteroid into a new orbit, either to mine or to remove from impacting earth (click on the Chapter 9 link in the text). Image courtesy of Dan Durda and the B612 Foundation.
Therefore, any long-range program of human exploration and settlement of the solar system must consider in situ resource utilization and the vital role that extraterrestrial energy minerals and related resources will play to support human habitation of near-Earth Space as well as on the nearby worlds of the Moon, Mars and the near-Earth Asteroids.
A good example of the memoir’s content, and of most interest to this readership, can be seen in the final chapter, authored by members of the Division’s Uranium and Nuclear Minerals Committee (UCOM): Nuclear Power and Associated Environmental Issues in the Transition of Exploration and Mining on Earth to the Development of Off-World Natural Resources in the 21st Century (Chapter 9). This chapter delves into the nuclear energy and environmental radiation aspects of living off-world.
Of course, adverse health effects from low levels of radiation are front and center in any future colony or long space flight, and the ugly beast of the Linear No-Threshold dose hypothesis (LNT) raises its head again. Beyond Earth’s atmosphere, the background levels of radiation are significantly higher than the average on Earth. But some areas on Earth have similar levels and astronauts have safely worked in space for years with no adverse health effects (Space Invaders).
Throughout our history, the dangers of a New World don’t seem to deter humans very much from venturing out to make whatever future they can in whatever environment there is. And in this one, there isn’t even any other people to fight or ecosystems to destroy in order to get there.
I say we go for it.

Posted by Nelio Inacio at 1:06 PM
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