Air Force Eyes Small Nuclear Reactors, Space-based Power

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GOLDEN, Colo. — The U.S. Air Force has laid out a new vision for its energy science and technology needs over the next 15 years — a forecast that includes plans for space-based power stations and the prospective use of small nuclear reactors for new spacecraft.

The report, titled “Energy Horizons: United States Air Force Energy S&T Vision 2011-2026,” focuses on core Air Force missions in air, space and cyberspace.

A series of workshops and summits were held to shape the new strategy.

The report was released Feb. 9 and details how the Air Force plans to increase energy supply, reduce demand and change military culture to meet mission requirements.

“Energy is a center of gravity in war and an assured energy advantage can enable victory,” Mark Maybury, chief scientist for the Air Force, said. He spearheaded the report.

“While energy is already an essential enabler, global competition, environmental objectives and economic imperatives will only increase its importance,” Maybury said.

Space is the “ultimate high ground,” providing access to every part of the globe, including denied areas, the report explains. “Space also has the unique characteristic that once space assets reach space, they require comparatively small amounts of energy to perform their mission, much of which is renewable,” it states.

The report mentions a number of desirable high-tech advances, including more robust satellite solar arrays.

Future space missions contemplated by the Air Force, other U.S. national security organizations and even NASA would require more electrical power than satellite builders can get out of today’s 27-kilowatt arrays.

“Employing larger and more efficient arrays will enable missions that require very high power, such as space-based radar or space-based laser missions,” the report states.

In the long run, the report says, increased solar cell efficiencies and revolutionary materials foreshadow the potential for 500 kilowatts of on-orbit power — a breakthrough “which would be transformational for performing missions from space-based systems.”

Among the technologies mentioned in the report: quantum dot and dilute nitride solar cells, electrodynamic tethers that could harvest energy from Earth’s geomagnetic field, advanced radioisotope power systems and even small modular nuclear reactors.

“While the implementation of such a technology should be weighed heavily against potential catastrophic outcomes, many investments into small modular reactors can be leveraged for space-based systems,” the report says. “As these nuclear power plants decrease in size, their utility on board space-based assets increases.”

Also addressed in the report is the wireless transfer of power, a technology that continues to offer big promises despite the daunting challenges involved in making it a reality.

While there are many challenges in “space-to-Earth” power beaming, “space-to-space power beaming” could be transformational, the report says.

The military could use wireless power transmission to power so-called fractionated satellite systems — think clusters of wirelessly connected orbiting modules acting as one — that could be smaller, harder to destroy and more capable than current systems.

The report also examines how alternatives to the silicon-based semiconductors found in today’s satellites will eventually result in more energy efficient systems that generate less heat than today’s chips. Advances in satellite propulsion are also spotlighted in the report. Today, the ability of space-based systems to alter their orbits is based on blasts of on-board fuel. The possibility of on-orbit refueling for these systems is now being studied.

In the mid- and far-term, the report suggests, other propulsion technologies will provide exceptionally efficient propulsion. That will allow the fuel onboard orbiting systems to be utilized for longer periods of time. Hall-effect thrusters, for instance, promise extended utility of limited onboard propellants.

Whatever the technology, new methods of generating power in space hold great promise for the Air Force’s plans for new satellites and other space missions.

The report’s cover letter, signed by both Secretary of the Air Force Michael Donley and Air Force Chief of Staff Gen. Norton Schwartz, explains how effective energy management not only plays a key role in supporting national objectives, but is also essential to operational readiness.

“Energy is essential to all Air Force missions,” the letter states. “Improving energy efficiency, reducing demand and changing the culture is vital to mission success.”