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posted by Fnord666 on Friday December 01 2017, @07:24AM   Printer-friendly
from the stirling,-not-sterling dept.

A NASA project will test a small nuclear fission power system that could provide kilowatts or megawatts of power for space missions:

In preparing for possible missions to the Red Planet in the near future, NASA's Space Technology Mission Directorate (STMD) has been given the go-ahead to test a small nuclear reactor that could one day run equipment on the Martian surface.

The Kilopower project[PDF] is working to advance a design for a compact, low-cost, and scalable nuclear fission power system for missions that require lots of power, such as a human mission to Mars. The technology uses a fission reactor with a uranium-235 reactor core to generate heat, which is then transferred via passive sodium heat pipes to Stirling engines. Those engines use that heat to create pressure, which moves a piston – much as old coal-powered ships used steam pressure to run their pistons. When coupled to an alternator, the Stirling engine produces electricity.

"What we are striving to do is give space missions an option beyond RTGs [radioisotope thermoelectric generators], which generally provide a couple hundred watts or so," Lee Mason, STMD's principal technologist for Power and Energy Storage at NASA Headquarters in Washington, D.C., said in a NASA news release. "The big difference between all the great things we've done on Mars, and what we would need to do for a human mission to that planet, is power."

Mason said the new technology could provide kilowatts of power and even be upgraded to provide hundreds of kilowatts or even megawatts of power. "We call it the Kilopower project because it gives us a near-term option to provide kilowatts for missions that previously were constrained to use less," Mason said. "But first things first, and our test program is the way to get started."

Stirling engine.

Also at World Nuclear News.


Original Submission

Related Stories

Initial Tests of NASA's Kilopower Nuclear System Successful 53 comments

Initial tests of NASA's Kilopower nuclear power system have been successful, and full-power testing will be done in March. Each Kilopower unit is expected to provide between 1 kW to 10 kW of electric power:

Months-long testing began in November at the energy department's Nevada National Security Site, with an eye toward providing energy for future astronaut and robotic missions in space and on the surface of Mars, the moon or other solar system destinations.

A key hurdle for any long-term colony on the surface of a planet or moon, as opposed to NASA's six short lunar surface visits from 1969 to 1972, is possessing a power source strong enough to sustain a base but small and light enough to allow for transport through space. "Mars is a very difficult environment for power systems, with less sunlight than Earth or the moon, very cold nighttime temperatures, very interesting dust storms that can last weeks and months that engulf the entire planet," said Steve Jurczyk, associate administrator of NASA's Space Technology Mission Directorate. "So Kilopower's compact size and robustness allows us to deliver multiple units on a single lander to the surface that provides tens of kilowatts of power," Jurczyk added.

[...] Lee Mason, NASA's principal technologist for power and energy storage, said Mars has been the project's main focus, noting that a human mission likely would require 40 to 50 kilowatts of power. The technology could power habitats and life-support systems, enable astronauts to mine resources, recharge rovers and run processing equipment to transform resources such as ice on the planet into oxygen, water and fuel. It could also potentially augment electrically powered spacecraft propulsion systems on missions to the outer planets.

NASA's next Mars mission is InSight, a stationary lander scheduled to launch in May. It will use two MegaFlex solar arrays from Orbital ATK. NASA's Mars 2020 rover is scheduled to launch in July 2020. It will use 4.8 kg of plutonium dioxide to provide no more than 110 Watts of power.

The Juno mission is the first mission to Jupiter to use solar panels. Juno uses 72 square meters of solar panels to generate a maximum of just 486 Watts at Jupiter. Mars receives about 12 times more solar radiation per m2 than Jupiter. The New Horizons mission to Pluto and Cassini–Huygens mission to Saturn both used radioisotope thermoelectric generators (RTGs). Cassini used three RTGs originally rated for 300 W each. A spare Cassini RTG was used for New Horizons, which provided 245.7 W at launch (~200 W by the Pluto encounter).

The Fission System Gateway to Abundant Power for Exploration

Also at NASA and Popular Science.

Previously: NASA's Kilopower Project Testing a Nuclear Stirling Engine


Original Submission

NASA's Kilopower Nuclear Reactor Exceeds Expectations in Tests 43 comments

NASA's Kilopower nuclear reactor with Stirling converters (not an RTG) has passed key tests:

The Kilopower team conducted the experiment in four phases. The first two phases, conducted without power, confirmed that each component of the system behaved as expected. During the third phase, the team increased power to heat the core incrementally before moving on to the final phase. The experiment culminated with a 28-hour, full-power test that simulated a mission, including reactor startup, ramp to full power, steady operation and shutdown.

Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.

"We put the system through its paces," said Gibson. "We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well."

The Kilopower project is developing mission concepts and performing additional risk reduction activities to prepare for a possible future flight demonstration. The project will remain a part of the STMD's Game Changing Development program with the goal of transitioning to the Technology Demonstration Mission program in Fiscal Year 2020.

The full system will generate 10 kW of power, but the prototype tested from November to March was designed to produce just 1 kW. The solid uranium-235 core is safe to handle.

The Kilopower Reactor Using Stirling Technology (KRUSTY) prototype exceeded almost all performance metrics.

Multiple units could power missions on the Moon, Mars, or other destinations:

"Kilopower's compact size and robustness allows us to deliver multiple units on a single lander to the surface that provides tens of kilowatts of power," NASA Associate Administrator Steve Jurczyk said in January.

Also at Beyond Nerva. 3m8s video.

Previously: NASA's Kilopower Project Testing a Nuclear Stirling Engine
Initial Tests of NASA's Kilopower Nuclear System Successful


Original Submission

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  • (Score: 3, Informative) by c0lo on Friday December 01 2017, @07:51AM

    by c0lo (156) Subscriber Badge on Friday December 01 2017, @07:51AM (#603830) Journal

    thermoacustic Stirling engine [youtube.com] (one of many on utube)

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  • (Score: 4, Insightful) by bradley13 on Friday December 01 2017, @08:19AM (10 children)

    by bradley13 (3053) on Friday December 01 2017, @08:19AM (#603832) Homepage Journal

    The problem with this concept: it is mechanical. A mechanical system just seems far too unreliable to send into space, land in foreign environments where you will have dust, wild temperature variations, and other problems. It seems like there must be a better way to turn large quantities of heat directly into electricity. Heat produces radiation. Solar cells turn radiation into electricity. Is it not possible to create cells that work from infrared?

    Or maybe capture the neutrons from the nuclear reaction, and put them on tiny bicycles?

    --
    Everyone is somebody else's weirdo.
    • (Score: 5, Interesting) by Aiwendil on Friday December 01 2017, @09:15AM

      by Aiwendil (531) on Friday December 01 2017, @09:15AM (#603842) Journal

      Toss the entire package into an hermetically closed system (makes it easier to deal with regulations that way, as well as shipping compact stirling engines enclosed are pretty run-off-the-mill these days for non-sheltered installations) and the issue of dust disappears.

      For longevity the stirling engine is impressive - you could easily make one that lasts decades (even easier if in a hermetically sealed enclosure).

      And since humany have experience in landing mechincal stuff on celestial bodies (despite an annoying gap between the mid-70s to the mid-90s) I would be more surprised if this stuff failed in the first decades than if it didn't.

      (And yes, there are ways to turn heat into electricity - but for the compromise between longevity, cost, weight, size and ease of build the stirling engine is hard to beat. Oh also, solar kinda sucks more the further away you get from the sun (earth happens to about as far away as when solar makes sense) - and the space programmes might want to explore Mars and not having to shut down each night when on a planet)

    • (Score: 2) by Geezer on Friday December 01 2017, @09:51AM

      by Geezer (511) on Friday December 01 2017, @09:51AM (#603846)

      I was going to say, even with the most modern methods of friction reduction, reciprocating machinery is still subject to inefficiencies due to too much moving mass and motive power being applied during only 50% of each rotation. Flywheels are kind of clunky, especially with variable power application causing vector inertial stresses on the machine.

      Granted a Stirling engine is simpler than a steam generation system, which is better suited to a water-depleted Martian environment, and maybe NASA sees dust as degrading PV panel or focused-mirror solar Stirling efficiency as a major obstacle.

      With cargo transportation to Mars being a big issue, a means of 3D-printing repair parts from locally-available materials to repair the inevitable breakdowns would seem to be essential.

    • (Score: 5, Informative) by c0lo on Friday December 01 2017, @12:50PM

      by c0lo (156) Subscriber Badge on Friday December 01 2017, @12:50PM (#603871) Journal

      A mechanical system just seems far too unreliable to send into space, land in foreign environments where you will have dust, wild temperature variations, and other problems.

      4 words: Free piston Stirling engine [wikipedia.org] - all the moving parts are enclosed hermetically in the cylinder.

      Old designs from NASA [nasa.gov] - 55% Carnot efficiency
      See here some explanations [youtube.com]

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    • (Score: 3, Interesting) by crafoo on Friday December 01 2017, @01:12PM

      by crafoo (6639) on Friday December 01 2017, @01:12PM (#603879)

      I don't think photovoltaic panels are necessarily more reliable or have longer useful lifespans than a well-designed and built mechanical system. I think your perception of mechanical systems is common, but is informed by cheap designed-to-fail trash that is common in our consumer world. There are many high-usage mechanical systems that last 20 years or more without maintenance or repair.

      Also a photovoltaic to transfer heat from a radioactive core would probably be massively inefficient.

    • (Score: 2) by DannyB on Friday December 01 2017, @02:28PM (4 children)

      by DannyB (5839) Subscriber Badge on Friday December 01 2017, @02:28PM (#603893) Journal

      I also came to complain about it being mechanical.

      Aside from the unreliability which you cover, I would point out the vibration induced by a piston system. Especially in space. There would be the constant vibration of pistons. This vibration would be induced throughout the entire structure. A rotating shaft with an alternator induces a rotational force upon the entire spacecraft which would require periodic compensation from thrusters.

      Sorry, due to new FCC deregulation, internet service is no longer available in your part of the city. To be notified if service becomes available in your area, enter your email address here.

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      • (Score: 0) by Anonymous Coward on Friday December 01 2017, @03:17PM (3 children)

        by Anonymous Coward on Friday December 01 2017, @03:17PM (#603924)

        A rotating shaft with an alternator induces a rotational force upon the entire spacecraft which would require periodic compensation from thrusters.

        I don't think thrusters are needed to compensate for unwanted rotation... you can use reaction wheels for that, right?

        • (Score: 2) by DannyB on Friday December 01 2017, @03:28PM (2 children)

          by DannyB (5839) Subscriber Badge on Friday December 01 2017, @03:28PM (#603931) Journal

          Yeah. More mechanical systems.

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          If we tell conservatives that the climate is transitioning, they will work to stop it.
          • (Score: 0) by Anonymous Coward on Friday December 01 2017, @04:23PM (1 child)

            by Anonymous Coward on Friday December 01 2017, @04:23PM (#603947)

            I for one look forward to our glorious mechanical future and the Victorian æsthetics it will undoubtedly renew. It's steampunk, just with nukes and no steam.

    • (Score: 1) by Muad'Dave on Friday December 01 2017, @06:07PM

      by Muad'Dave (1413) on Friday December 01 2017, @06:07PM (#603985)

      It seems like there must be a better way to turn large quantities of heat directly into electricity.

      That's the old RTG [wikipedia.org] they're trying to get away from.

  • (Score: 2) by PiMuNu on Friday December 01 2017, @09:10AM (7 children)

    by PiMuNu (3823) on Friday December 01 2017, @09:10AM (#603840)

    It doesn't say it in the summary, and it is hard to get out of the article, but I think the point is that this enables deployment on the Martian poles where sun is hard to come by. My impression however is that solar gives more energy/kg. Can anyone confirm?

  • (Score: 3, Funny) by Runaway1956 on Friday December 01 2017, @03:06PM (2 children)

    by Runaway1956 (2926) Subscriber Badge on Friday December 01 2017, @03:06PM (#603917) Journal

    Why don't they just start cutting down the Martian forests to use in steam generators?

    (I had nothing else to offer, thought I'd give the trolls something to bite on!)

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    • (Score: 2) by DannyB on Friday December 01 2017, @03:29PM

      by DannyB (5839) Subscriber Badge on Friday December 01 2017, @03:29PM (#603932) Journal

      First we'll have to grow Martian forests.

      --
      If we tell conservatives that the climate is transitioning, they will work to stop it.
    • (Score: 0) by Anonymous Coward on Friday December 01 2017, @03:34PM

      by Anonymous Coward on Friday December 01 2017, @03:34PM (#603937)

      I thought it was obvious. There isn't a lot of oxygen on Mars, the marsonauts will prefer to use it for breathing.

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