One of the primary, long-standing goals of space exploration is the development of a small/light-weight, long-lasting power source for long-term space missions. Solar panels become less practical as one ventures further into space (past Mars), as available solar energy diminishes greatly; use of solar panels on deep space probes would require greatly increasing the size of these panels (up to a football field in length!), making them highly impractical.
Even newly developed solar-ion propulsion engines may not be practical for larger probes and missions to (and beyond) the outer solar system as the solar wind also diminishes at these distances.
Until some long-lasting, alternative power source is discovered, nuclear power is our best choice for long-term space probe needs.
So, with this newest prototype, scientists have come closer to realizing this critical goal.
What’s more, the basic concept underlying this newest engine design actually comes from the 19th Century! It’s called the Stirling engine – an engine that utilized hot pressurized gas to push a piston.In the envisioned form, the engine would be comprised of a 50 pound “nuclear uranium battery” used to generate the required heat (and thus also pressure) which is then channeled to eight Stirling engines which convert this mechanically into electrical power. This as-yet-unrealized version would be capable of producing 500 watts of power — just barely enough to power all on-board control, sensor, and data transmission systems.
The prototype developed by engineers at NASA’s Glenn Research Center and Los Alamos National Laboratory is a much more modest design using a small nuclear source and just one Stirling engine, yielding only 24 watts of power. This is too little to power a space craft, even a small one. Most deep space probes require at least 600 watts of power.
But the space scientists involved in this project are confident that this prototype nuclear engine can be scaled up to suit the needs of future space probe missions.
According to WIRED (see source link below), this effort represents “the first test of a nuclear reactor system to power a spacecraft conducted in the U.S. since 1965.”
This new uranium-based engine prototype comes along at a good time. Up until now, NASA has used plutonium-238 as a power source in its deep space probes, like the Cassini probe currently orbiting Saturn. However, in the 1980’s The U.S. began decommissioning its plutonium production sites, such that, as of now, little is left for space missions. Some of the last useful quantities of the radionuclide are now powering the Curiosity rover as it investigates the surface of Mars.
But, in 2011, NASA and the Department of Energy received significant funding to restart plutonium production which would make a few pounds of the highly-coveted material available each year for space missions (including those from other countries). But the small yield per cost make this less practical in the long-term.
By further refining this newest nuclear engine design, it would likely decrease demand for the more expensive plutonium and make for a more practical and plentiful nuclear energy source for space missions for many decades to come (or until we finally achieve ‘warp drive’ capability).
Source for this post: WIRED News article ‘New Nuclear Engine Could Power Deep-Space Exploration’
Top Image: A proposed deep-space probe to Jupiter that uses the radioactive nuclear engine proposed at NASA and Los Alamos. Los Alamos National Laboratory