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NASA successfully tests nuclear reactors for deep-space exploration

NASA, along with the Department of Energy, announced Tuesday that initial tests of a reliable nuclear reactor based on current technology show that it could serve as a reliable source of energy for deep-space spaceships.

The Demonstration Using Flattop Fissions (DUFF) experiment produced 24 watts of electricity, according to NASA.  A team of engineers from Los Alamos, the NASA Glenn Research Center and National Security Technologies LLC (NSTec) conducted the experiment. The test is seen as a key step towards creating a nuclear-powered deep-space spacecraft, which would require fuel sources capable of lasting upwards of forty to fifty years. The current setup is reportedly based on technology available as far back as 1960.

NASA reportedly relied on Heat pipe technology, which was invented at Los Alamos in 1963. A heat pipe is a sealed tube with an internal fluid that can efficiently transfer heat produced by a reactor with no moving parts, and it requires a Stirling engine — a relatively simple closed-loop engine that converts heat energy into electrical power using a pressurized gas to move a piston. Using the two devices in tandem allowed scientists to create a simple, reliable electric power supply that can be adapted for deep-space spaceflight.

“The nuclear characteristics and thermal power level of the experiment are remarkably similar to our space reactor flight concept,” said Los Alamos engineer David Poston. “The biggest difference between DUFF and a possible flight system is that the Stirling input temperature would need to be hotter to attain the required efficiency and power output needed for space missions.”

“The heat pipe and Stirling engine used in this test are meant to represent one module that could be used in a space system,”  added Marc Gibson of NASA Glenn Research Center. “A flight system might use several modules to produce approximately one kilowatt of electricity.”

For the last several decades, NASA has relied on plutonium-238 to power its deep-space probes, including Voyager and Cassini. Beginning in the early 1980s, the U.S. began decommissioning its plutonium production sites. By 1988 the U.S. supply had dwindled and  NASA was forced to augment the demand by purchasing the last remaining stock from Russia. However, Russia later reneged on its contract, forcing delays to supply the U.S.  The contract dispute was finally resolved in 2011 when NASA and the Department of Energy received about $10 million to restart plutonium production, allowing for its use in future space travel.

Overall, the test could pave a path towards more advanced space missions. The availability of more power could potentially boost the speed with which mission data is transmitted back to Earth, or increase the number of instruments that could be operated at the same time aboard a spacecraft, according to NASA. A power system based on the concept demonstrated by DUFF could also be attractive for future space exploration missions that may require significantly higher power levels than current systems can easily provide.

“Perhaps one of the more important aspects of this experiment is that it was taken from concept to completion in six months,” said Los Alamos engineer David Dixon. “We wanted to show that with a tightly-knit and focused team, it is possible to successfully perform practical reactor testing.”

While concerns over a potential cataclysmic accident remain a major hurdle, the scientists say the reactor would not begin to function until the spacecraft exited Earth and was safety in space, making accidents on the ground or during launch largely avoidable. Additional tests are planned in the near future, possibly allowing for reseachers to better understand how nuclear power could be used in deep-space flight.

“A small, simple, lightweight fission power system could lead to a new and enhanced capability for space science and exploration,” noted Los Alamos project lead Patrick McClure.  “We hope that this proof of concept will soon move us from the old-frontier of Nevada to the new-frontier of outer space”.

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