Dec 292016

I’d posted this YouTube video a few years ago, but I’ve found that not only was the video yanked, the whole account associated with it was nuked. Hmmmph.

A film about NERVA (Nuclear Energy for Rocket Vehicle Applications), 1968.

Provides a basic description of nuclear rockets, plus some art, animation and diagrams of nuclear propelled space vehicles along with footage of test firings.



 Posted by at 2:24 am
  • John Nowak

    Fascinating stuff. I was particularly struck by the rotating control rods.

  • sferrin

    I happened to have saved off a higher rez version before it disappeared.

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    • se jones

      thanks for doing that sferrin

  • Some nice shots of the NTRS and the Aerojet H area as well.

  • se jones

    NASA Keeping Nuclear-thermal Option Open For Mars
    Oct 26, 2016 Frank Morring, Jr. | Aviation Week & Space Technology

    Safer fuel and a new concept for ground testing have nudged NASA another tiny step in the direction of using hydrogen heated by a small fission reactor to hasten humans on their way to Mars.

    Nuclear-thermal propulsion (NTP) has been studied since the Apollo era because of the high specific impulse it offers for deep-space missions, but radiation fears and technical difficulties ultimately have blocked it. Now, with low-enriched nuclear fuel instead of bomb-grade material, and what may be a safer way to capture radiation in ground-test plumes, the technology is getting another look.

    Engineers here at NASA Marshall Space Flight Center in Huntsville, Alabama, are working with the commercial nuclear-power industry and academia to raise the technology readiness level of space-rated reactors with low-enriched uranium fuel. And at Stennis Space Center in Mississippi, propulsion-test experts may be able to reconfigure ground equipment originally designed to simulate high-altitude chemical-rocket engine starts to capture and decontaminate a nuclear-thermal rocket plume.

    >No bomb-grade fuel needed
    >New ground-test concept
    >Reducing exposure to deep-space hazards
    >Possibly aborting a Mars mission

    “There is interest,” says Mike Houts, nuclear research manager at Marshall. “It seems to come back to whether we can make NTP affordable and viable, because the performance advantages—between the 900-sec. specific impulse, at a high thrust-to-weight ratio relative to other options at that high a specific impulse—give you a lot of mission flexibility, a lot of robustness in the architecture.”

    A cluster of three 25,000-lb.-thrust NTP engines firing for a total of about 2 hr. could cut the duration of a human Mars mission in half, from about 900 days to about 450 days. The system would fire in Earth orbit to speed a crew to Mars in as little as four months, instead of six or more with a chemical-propellant boost, and again as the spacecraft reaches Mars to slow it for orbital insertion.

    Reducing the mission duration would cut the crew’s exposure to galactic cosmic rays and other dangerous deep-space radiation that remain one of the primary health concerns on a Mars mission, along with prolonged microgravity and the psychological effects of isolation and confinement.

    It might also enable mission aborts under some circumstances—a subject NASA is just starting to study. And it would broaden somewhat the planetary launch windows that occur every 26 months when Mars and Earth are best aligned with each other in their orbits around the Sun. With that flexibility in designing missions comes flexibility in designing the life-support and other systems necessary for survival and success.

    “People will talk about just the reliability of the system,” says Houts. “Usually, if someone is pushing for a shorter time away from Earth, they will just point out it’s just that much less time all these systems have to work, across the board.”
    “It’s almost more like a heat exchanger than a combustion chamber,” says Houts. “The heat is generated in the core, and that just transfers to the hydrogen.”

    The hydrogen also would drive the turbomachinery that pumps it into the reactor. A 25,000-lb.-thrust engine would weigh about 3,000 kg (6,600 lb.) in the designs currently under study at NASA, with the reactor measuring about 1 m (3.2 ft.) in diameter and height.

    The new wrinkle is the use of low-enriched uranium—less than 20% of the U-235 isotope that supports fission—instead of uranium with a higher enrichment that requires elaborate and expensive handling and security measures because it also can be used in nuclear weapons. The same material heats the water that makes electricity in nuclear power plants, so there is an industrial base for making, using and disposing of it.

    In the NTP laboratory here, Houts and his colleagues use rods containing 100-micron beads of depleted uranium in lieu of the low-enriched version. The goal is to develop the most efficient design for the fuel pellets, which would be encased in tungsten cladding, and the larger rods.

    A single rod is heated to operational temperatures with radio-frequency (RF) induction coils, and engineers study the thermal profiles and other data generated when hydrogen is passed through it in a pressure chamber rated at 11,000 psi (see photo). Marshall also is equipped to test smaller rods of low-enriched uranium to refine the design, still with RF heating instead of fission.

    Although an inactive NTP system is not inherently dangerous, the byproducts of a fission reaction are radioactive. That makes ground testing a delicate problem, particularly with hardware that is designed to operate in vacuum.

    At Stennis, engineers are studying whether it will be possible to adapt the E-3 test stand—a subscale development version of the A-3 stand built to simulate high-altitude ignition of the J-2X upper-stage engine—to test an NTP engine.

    “Since the [nuclear-thermal rocket] uses hydrogen propellant, when the hydrogen exits the engine, [one could] go ahead and combust it,” says Houts. “Once you have combusted it, now you have basically water. It’s a reasonable volume of water that you can condense, and then you basically hold onto that water and check it for contamination. If the fuel worked perfectly you would not have contamination of the water, but the fuel probably will not work perfectly because it’s a test. So what you would do is remove the contamination just using commercially available technology, the same as what’s done at terrestrial nuclear power plants.”

    Just like using low-enriched uranium to lower the cost of handling nuclear fuel, the approach Stennis is investigating could make it possible to test a high-performance NTP engine on the ground safely instead of using an expensive flight test.

    Compared to the sums NASA is investing here to develop the heavy-lift Space Launch System (SLS), NTP funding is tiny—about $6.9 million a year. In addition to the SLS, a chemical propulsion system, the U.S. agency is also developing advanced solar-electric propulsion systems to preposition large payloads such as habitats and supplies at Mars. An NTP flight demonstration remains “notional” at best. That does not mean it is not a good idea.

    “I’ve always thought that eventually we would get to a nuclear stage,” says Garry Lyles, chief engineer on the SLS program. “It’s kind of my favorite translunar stage. But it is obviously not in the same technical readiness level that a chemical stage is. So I would think, if I was looking in the future, I would see us evolving to that.”