NASA Will Flight Test a Nuclear Rocket by 2024 and Other High Tech NASA Projects

A portion of NASA’s $21.5 billion 2019 budget is for developing advanced space power and propulsion technology. NASA will spend $176 to $217 million on maturing new technology. There are projects that NASA has already been working on and others that NASA will start and try to complete. There will be propulsion, robotics, materials and other capabilities. Space technology received $926.9 million in NASA’s 2019 budget.

NASA’s space technology projects look interesting but ten times more resources devoted to advancing technological capability if the NASA budget and priorities were changed.

NASA is only spending 1 of its budget on advanced space power and propulsion technology. NASA will spend $3.5 billion in 2019 on the Space Launch System and Orion capsule. SLS will be a heavy rocket which will start off at around the SpaceX Heavy capacity and then get about the SpaceX Super Heavy Starship in payload capacity. However, the SLS will cost about $1 billion to launch each time which is about ten times more than SpaceX costs. NASA is looking at a 2021-2022 first launch and then a 2024 second launch. This would be $19+ billion from 2019-2024 to get two heavy launches and this is if there are no delays.

NASA is making critical advancements in power generation and energy storage technologies for science and human exploration missions. Propulsion investments focus on higher thrust and efficiency, including alternatives to traditional chemical propulsion systems for deep space exploration spacecraft systems.

Specific investments include development of solar array technology that can generate energy in extreme environments including low light intensity and low temperature; development and testing of a scalable 1kW surface fission power generation system; and rapid transit nuclear thermal propulsion technology utilizing low-enriched uranium that could potentially provide 20 percent shorter travel time to Mars while substantially improving mission flexibility.

The US Congress has approved $100 million for NASA to develop nuclear thermal rocket engines. NASA plans to conduct a flight demonstration by 2024 is new.

BWXT Nuclear Energy is working with NASA on initial nuclear thermal reactor conceptual trades and designs, initial fuel and core fabrication development, licensing support for initial ground testing, and engine test program development.

LEU Nuclear Thermal Propulsion

Current development is for a 500 Megawatt LEU CERMET fuel reactor for manned space applications.

* Design of 19.75% Enriched Ceramic Metallic (CERMET) Tungsten-Clad fuel
* Nuclear, thermal-hydraulics and mechanical design of the reactor
* Licensing and design support for full-scale full-thrust ground test of the NTP engine

Key projects that support this thrust area include the following:

* Kilopower: Through a partnership with Department of Energy’s National Nuclear Security Administration and Los Alamos National Lab, and small businesses Sunpower, Inc and Advanced Cooling Technologies, NASA is developing a 1kW prototype of a fission power subsystem that is scalable and will potentially provide surface power capability for space exploration. The Kilopower assembly went through vacuum testing at Glenn Research Center for thermal cycling checkout, and will conduct full power test in early FY 2018 at the Nevada National Security Site.

If successful, NASA will advance this effort to a flight demonstration, and ultimately a 10 kW system for surface power.

* Nuclear Thermal Propulsion (NTP): Investments will enable more efficient spaceflight by developing improved fuel element sources to support potential future nuclear thermal propulsion efforts. In FY 2018, the nuclear thermal propulsion project will continue to refine the NTP technology maturation and ground demonstration plan; complete assessment of a NTP Mars transportation architecture; continue feasibility analysis based on cermet fuel element/reactor conceptual design; update and deliver a final Low-Enriched-Uranium (LEU)-based nuclear thermal propulsion system cost analysis; and refine the fuel element reactor conceptual design.

Industry and government involvement include Aerojet Rocketdyne, AMA, Aerospace, BWXT, and Department of Energy. Risk mitigation activities will complete in FY 2019, culminating in a concept review and determination of whether to proceed with a ground demonstration phase.

* Sub Kilowatt Electric Propulsion: NASA will demonstrate a ~0.5 kW Hall electric propulsion thruster to be used on ESPA class spacecraft that support exploration and science missions. Recent advances in Hall thruster technology at the 13-kW power level can be applied to 0.5 kW device to drastically alter the spacecraft market with low development risk. The project plans to deliver an engineering qualification model thruster and PPU design in FY 2019 and eventually complete an integrated (xenon and iodine) thruster testing.

* 600W Hall Thruster Qualification Life Test: Through an Announcement of Collaborative Opportunity (ACO) in FY 2018, NASA awarded Busek a three-year project to perform life testing of the BHT-600 Hall Effect Thruster and BHC-1500 Hollow Cathode Assembly (HCA) coupled to a Power Processing Unit. This technology could be infused into sub-KW power level Electric Propulsion systems.

* Modular Power Systems will demonstrate a modular power architecture composed of technologies for power generation, energy storage, power distribution and health management that will reduce the cost of future space systems.

* Other ongoing initiatives include work on advanced propulsion under the NextSTEP BAA awards and modular power for multiple exploration vehicles and systems such as fuel cells.

Advanced Communications, Navigations and Avionics

NASA will fundamentally transform spacecraft systems through investment in high payoff technologies
that increase communication data rate and advance deep space navigation and flight avionics. Key
projects within this portfolio include the following:

* High-Performance Spaceflight Computing: With the Air Force Research Laboratory, NASA is developing a next-generation high-performance space flight computing system that will lead to vastly improved in-space computing performance, energy management, and increased radiation fault tolerance. The new radiation tolerant microprocessor will offer a 75 times improvement in performance relative to the current state of the art RAD750 processor while requiring the same power.

* Software Defined Reliability for Mission Critical Operations: through an FY 2018 ACO, awarded to Astrobotic Technology, this two-year project will mature Astrobotic’s software-defined reliability system for computing.

* Communicating from Earth to any spacecraft is a complex challenge, largely due to the extreme distances involved. When data are transmitted and received across thousands and even millions of miles, the delay and potential for disruption or data loss is significant. Delay/Disruption Tolerant Networking (DTN) is NASA’s solution to reliable internet working for space missions.

* Ka-Band Objects Observation and Monitoring (KaBOOM) will use three 12-meter diameter antennas at NASA’s Kennedy Space Center (KSC) to demonstrate a Ka-Band phased array of widely separated antennas that can instantly compensate for atmospheric twinkling to improve what is seen.

NASA Advanced Material Projects

NASA supports innovation in materials development and low-cost manufacturing that enables increased mission cargo capacity by reduction of structural mass. NASA looks for opportunities to improve the manufacturing technologies, processes, and products prevalent in the aerospace industry. NASA’s unique needs enable a network of collaboration and partnerships with industry, academia, and other government agencies to accelerate innovative manufacturing methods and technologies. Key projects within this portfolio include the following:

* Advanced Near Net Shape Technology: This technology uses innovative metal forming techniques to manufacture integrally stiffened aerospace structures such as cryotanks. The resulting product is 50 percent lower cost and 10 percent lighter due to fewer welds and minimized machining. NASA will build on previous prototyping efforts focusing on scaling up the process for commercial launch vehicles.

Industry partners include MT Aerospace, Lockheed Martin, and Leifeld Metal Spinning, in Ahlen, Germany.

* Additive Construction for Mobile Emplacement: will develop full-scale hardware to 3D print infrastructure components using analog planetary in-situ materials, while developing full-scale hardware with the United States Army Corps of Engineers for terrestrial applications.

* Bulk Metallic Glass: Bulk Metallic Glass gears improve rover mobility performance at low temperatures by eliminating the need for gear lubricant and associated heaters. This project will deliver planetary gears and strain wave gears that will enable planetary surface missions where temperatures drop below the freezing point of typical lubricants.

* Composite Technology for Exploration: By developing new analytical methods to design, build and test innovative hardware, NASA looks to enable a significant increase in the use of new composite materials for the next generation of rockets and spacecraft needed for space exploration.

* The Rapid Analysis Manufacturing Propulsion Technology (RAMPT) project will develop and advance large-scale lightweight manufacturing techniques and analysis capabilities required to reduce design and fabrication cycles for regenerative-cooled liquid rocket engine components.

RAMPT impacts all phases of the thrust chamber life cycle by reducing design, fabrication, assembly schedules (60%) and allowing for reduced parts, increased reliability, and significant weight reduction (70%). RAMPT will partner with industry through a public-private partnership to design and manufacture component parts of the thrust chamber.

* Deployable Composite Boom: The objective of this project is to mature deployable composite boom technology for use in low-cost, small volume, CubeSat/ESPA class spacecraft deployable systems. A technology gap has been identified for deployable composite booms that are 5-20 meter long and capable of packing into a 0.5-3 U volume. These types of booms enable high power solar arrays, antennas for high data rate communications, and high Delta-V propulsion systems to be included on small CubeSat/ESPA class spacecraft.

* In an effort to provide efficient mission and ground operations with reduced dependence on Earth resource, NASA is continuing to invest in in-space manufacturing technologies, including the development of the FabLab for ISS.

Advanced Life Support

NASA will fundamentally transform spacecraft systems through investment in high payoff technologies that advance atmospheric capture and conversion aspects of in-situ resource utilization technologies, closed-loop life support systems, and develop capabilities to mitigate space radiation. Key projects within this portfolio include the following:

* Advanced Radiation Protection: Insufficient data exists to validate thick shield space radiation exposure predictions. The Advanced Radiation Protection project will validate the shielding efficiency of spacecraft materials and verify an optimum Galactic Cosmic Ray shield thickness needed for minimal mass vehicle design. To this end, the project team will work with the NASA Space Radiation Laboratory to design and build radiation detector stands and targets to support a testing of various materials (aluminum, polyethylene, combination). This effort will result in data that will inform deep space habitat construction. This project can be viewed as the necessary first step in the development of a vehicle optimization capability for long duration, heavily shielded vehicles.

* Spacecraft Oxygen Recovery: Oxygen recovery systems are critical when oxygen resupply from Earth is not available, and will be enabling for long-duration human missions. NASA awarded two contracts, Honeywell Aerospace and UMQUA Research Co., to develop technologies that will increase the oxygen recovery rate aboard human spacecraft to at least 75 percent while achieving high reliability. Future maturation of these technologies may be used by the ISS as a proving ground to retire risk and gain experience with capabilities needed for deep-space exploration.

* The Korea Pathfinder Lunar Orbiter (KPLO) spacecraft will carry a total of five instruments to lunar orbit—four from South Korea and one from NASA (developed by Arizona State University and Malin Space Science Systems). ShadowCam, the US provided instrument, will map the reflectance within the permanently shadowed regions to search for evidence of frost or ice deposits. The instrument’s optical camera is based on the Lunar Reconnaissance Orbiter Narrow Angle Camera, but is 800 times more sensitive, allowing it to obtain high-resolution, high signal to-noise imaging of the moon’s permanently shadowed regions. ShadowCam will observe these regions monthly to detect seasonal changes and measure the terrain inside the craters, including the distribution of boulders. ShadowCam will address strategic knowledge gaps, or lack of information required to reduce risk, increase effectiveness, and improve the designs of future human and robotic missions.

Autonomous Systems

Autonomous systems are critical when exploring or operating in an extreme environment, on Earth or in space (especially for outer planets exploration). This portfolio supports technologies that benefit space exploration and also support manufacturers, businesses and other entities. Key technology efforts include:

* Autonomous Medical Operations: The objective of this project is to develop a “medical decision support system” to enable astronauts on long-duration exploration missions to operate autonomously while independent of Earth contact. Such a system is not intended to replace a “Chief Medical Officer” (CMO), but rather to support the CMO’s medical actions by providing advice and procedure recommendations during emergent care and clinical work. The Autonomous Medical Operations system will enable rapid, assured acquisition and analysis of sensor data to support differential diagnosis; analysis from medical on-board notes and on-board databases (including tailoring to individual astronauts); and automated reasoning using structured and unstructured data.

* Autonomous Pop Up Flat Folding Exploration Robot: The objective of this project is to enable the “Pop-Up Flat Folding Explorer Robots” (PUFFER) to operate autonomously, both individually and as a multi-robot team. PUFFER is a miniature mobile robot that is designed as a low-volume, low mass, low-cost mission enhancement for accessing new high-interest extreme terrains. PUFFER is capable of supporting future lunar, Mars and icy moon missions, as well as extreme terrains on Earth.

Entry and Landing Systems

In order for NASA to land more mass, more accurately on planetary bodies, as well as improve capabilities to return spacecraft from low Earth orbit and deep space, the Agency must develop more capable entry, descent, and landing systems, materials, and modeling capabilities. NASA invests in technologies focused on the design, analysis, and testing of advanced materials for thermal protection and aeroshell architectures required for future exploration vehicles and planetary entry missions. Key projects within the Entry, Descent and Landing Systems include:

* Safe and Precised Landing Integrated Capabilities Evolution (SPLICE), a precision landing and hazard avoidance technology, will be infused into future robotic science missions. The project will strive to tie entry uncertainty to a safe & precise landing. By the end of the project, the goal is to reach 200m/s with Line of Sight Velocity and greater than 4 km in Line of Sight Range.

* Heat Shield for Extreme Entry Environment Technology (HEEET) is an advanced thermal protection system that consists of a high-density all-carbon surface layer below which is a lower density layer composed of a blended carbon phenolic yarn which is then infused with a middensity level of phenolic resin. The mass efficiency of HEEET permits exploration and science missions to target much lower entry g-load compared to current state-of-the-art.

* NASA will emphasize technologies to enhance lander technology and improve autonomous precision landing with hazard avoidance on lunar and planetary surfaces. NASA shares these landing capabilities through public-private partnerships with industry through multiple partnership and contract mechanisms.

SOURCES- NASA, Congress, Youtube, BWXT

Written By Brian Wang. Nextbigfuture

98 thoughts on “NASA Will Flight Test a Nuclear Rocket by 2024 and Other High Tech NASA Projects”

  1. The moon wasn’t always dead, and isn’t always dead. Early in its history it had water, volcanoes and lava. We should look before assuming anything.

    I doubt large amount of radioactive material will be allowed to be launched. But maybe U238 and Thorium will be allowed.
    Accelerators could be used to convert those material into fissile isotopes.

  2. Ya I did a lot of dangerous things when I was kid. I had many friends who’s parents banned their children from hanging around me in my neighborhood. Every time the neighbors heard a loud bang in the distance, they would come out and I would come walking down the street with a duffel bag of stuff. I started with model rockets in like 4th and 5th grade, I turned into a controlled pyro,

    I was shooting off a potato launcher mortar I made for a science class project (my teacher was a Vietnam vet and approved) and a Girl Scout troop that was at a nearby park called the cops which triggered a SWAT search of the area, helis and all. I was home by the time the full search started.

    I came out and showed them the launcher and the science paper (it was on calculating muzzle velocity, by measuring angle, distance and flight time) I was working on and they laughed it off. They told me to call them next time in advance. I never showed them the explosives I was actually firing out of it. I was trying to get the right fuse length for the timing fuse so it would explode above the ground. I never got it right.

  3. The Space Force ? Give us a break.. How many billions did Reagan waste on Star Wars ? If you Yanks keep electing second rate actors to run the country, it’s no wonder you’ve got a Tinseltown space industry. Those guys are supposed to read a script, not write it, and Trump can’t even do that reliably.

  4. Uranium ores on earth were concentrated by flowing groundwater, especially after the development of an oxygen atmosphere. Deposits on the Moon are likely to be much more dilute, so it should be easier to bring it from Earth. Thorium is mostly obtained from monazite, which has been swept onto beaches by the ocean. No beaches on the Moon. High assay uranium or plutonium would be worth its launch mass, being far more energy dense than any other fuel.

  5. Sadly I live in an evil dictatorship that places a lower importance on normal people enjoying themselves than is placed on the injuries self inflicted by moron losers who were never going to achieve anything anyway.

  6. Pre-911 there was a cool website called United Nuclear where you could order small amounts (100-200 g or so) of the various compounds (sulfer, aluminium powder, and timing fuse) needed to make some crazy homemade fireworks. Another thing was to just purchase some legal fireworks and take them apart and use clay screens to separate the different components.

  7. A screamer firework does the trick. Just unwrap it and take out its insides. Pinching the top of those essentially makes a little explosive charge. They are mostly sulfur.

  8. Brown powder at best. Black powder needs sulphur too.

    Brown powder = charcoal that isn’t quite fully carbonized, plus ammonium nitrate. The presence of some remaining cellulose/lignite compensates for the lack of sulphur in getting the burn rate up. For a simpler recipe with less rare ingredients it is surprisingly MORE powerful and was used instead of black powder for artillery and naval guns at the end of the 19th C. But I think it’s harder to ignite, which is why the older recipe bothers with the (sometimes difficult to source) sulphur.

  9. See if this works:

    Note: the data is from 2010. They have made cell improvements since then. The substrate is whatever the panels are mounted on:

    It can be anything from part of the satellite structure, to folded Kapton film, as used in the ISS arrays. For high power electric propulsion I assume folding Kapton film, in order to pack it in a manageable size for launch. The film is very lightweight.

    Communications satellites tend to use rigid substrates, because the array folds out from the sides of the satellite body with hinges.

  10. Take a bunch of charcoal ash, put it in 1L containers, then piss in it for a few days till it is soaked in piss, let it dry out after each soaking and repeat about 7-8 times. Add ammonium (windex) to speed up. Ash and windex. Then you will have black powder.

  11. Come to think of it. I pretty much used Estes model A rocket motors and/or the electric ignition fuse thing to ignite the bulk of my pyro experiments. I bought a few of them and had to splice wires back together. Good times.

  12. I made thermite once. I had to steal a bit of magnesium ribbon from science class so I could test it.

  13. Well, no, right now fusion gets special allowances as the best that’s supposed to be the death of the good enough, fission.

    It will lose that special treatment as soon as it appears to be practical itself.

    The only practical seeming fusion rocket proposal I’ve seen (Aside from Orion, of course!) is PUFF: “Pulsed Fission- Fusion”. Basically a z-pinch initiated combined fission and fusion bomb that’s tiny enough to explode inside a magnetic confinement rocket engine. (The fusion just releases a burst of neutrons to take the tiny amount of fissile material over effective critical mass, most of the energy released is from fission.)

    It’s still open cycle and produces radioactive exhaust, so it would never be permitted to be used in our atmosphere or near it. As a technical matter it could be tested on Earth in a suitable facility, but I doubt that, as a political matter, that would be permitted.

  14. I was more into incendiaries as a kid; Got extra credit in HS chem class by sharing my copper based thermite recipe with the instructor. (Iron based thermite gives you molten iron, copper based thermite gives you copper vapor.)

  15. When I was 15 I managed to make ~100g of C4. I forget the exact recipe, but it was pretty dangerous, involved boiling bleach and other household chems, freezing the substance and collecting the crystals formed, then combining with other stuff. Needed a gas mask to do it. All that chlorine gas. Had to duct tape the the chunk of stuff to a A sized model rocket motor to blow it. Made a cool crater in the field behind my dads house (did it in the winter after a good rain to avoid a fire). Created a mortar once to with an abs potato launcher and some of those screamer fireworks.

  16. Your math looks right, and I verified them against Vmp * Jmp as well (which come out slightly higher). I would be interested in seeing the wiring and structural numbers, if you have them handy.

  17. Three layer, Carbon-Carbon lining, covered by solid tungsten alloy sleeve, with a thicker tungsten alloy CMF cover for the chamber.

  18. Multiple timed burns? Run it at burst intervals. the first for orbital exit velocity, the next burns a day or so later to gain speed for different destinations. A few small directional thrusts to make trajectory changes.

  19. I’m going to guess that any location (translate: anywhere except high Earth Orbit or further) where you won’t be allowed to test a rocket spraying fission products into the atmosphere, will ALSO not accept a test that sprays fusion products into the atmosphere.

    So… any method that lets you design fusion rockets would also let you design fission rockets.

  20. It’s got that old fashioned American “documentary describing tech” accent and way of talking that I associate with trusted and reliable information sources.

    It’s a very distinct style of speaking, that produces an instant (positive) emotional response in me.

    Distinct from the classical British technical/news video announcer style, which I always associate with British comedies aping the same style, and hence can’t take seriously.

    Or the modern American version of the same style that I (sadly) have come to instinctively associate with scams and propaganda. Doesn’t matter what the video is about, if it is narrated with the modern American informational video narration style my brain tells me “this is spam. This is an advertisement. This is all a scam somehow and they are trying to get your money/votes/conformity.”

  21. Yes, this is well understood by everyone working in the field. The current working limit is Jupiter, where the Juno probe is solar-powered. The previous Galileo probe used an RTG (plutonium decay), but solar technology has improved in-between.

    Mars surface is mission-dependent. The Curiosity rover uses nuclear RTG, while the new Insight mission is solar. It is stationary and has fewer instruments, so can go solar.

  22. As long as people are not aboard, a slow traverse through the Van Allen belts is not that big a problem. Have your main ship do the slow but efficient climb, then send a crew capsule to dock once they are near the top of the Earth’s gravity well.

    Nominally, a 1 MW solar-electric system will produce ~ 28.5 N thrust, which equates to 275 kg of nuclear-thermal propellant/day. Depending how big your mission is will set the time to climb.

    I’m in favor of a system architecture that keeps your electric vehicles high in gravity wells after first delivery. So it may shuttle from near the Moon, to high Mars orbit and back. You use small capsules to get up and down at each end.

  23. > You have a reference on that 175 W/kg number?

    Using upper end cell mass of 84 mg/cm^2 = 0.84 kg/m^2. End of life (EOL) efficiency 26.7% x 1362 W/m^2 solar flux at 1 AU = 363.6 W/m^2. Dividing gives 432.9 W/kg. This is for just the cells. Adding structural support and wiring brings it to 175 W/kg for a panel.

    I have a pdf that shows the latter figure, but apparently Spectrolab doesn’t have it on their website any more. I’ll be happy to post it online if you want a copy.

  24. Yes, Orion (the real one, not the later fake orion) was the nuclear pulse drive and that was talking about numbers like 2% of C, maybe up to 10% of C for a really big one (they apparently scale up well).

  25. Adding a nuclear reactor to your design will really quickly add a lot of expense and difficulty to your project.


  26. It’s just bad physics telling you that you need to do something else. Spewing fission products is no problem in space but you still have the expense of the fuel… if it were common material, spew away. It’s not common.

  27. Exactly. Paradigm shift needed. Can’t contain 1000 ISP, whatever it is. So we either go magnetic and battle to contain, at great expense and complexity, or pulse and ablate material.

    Honestly, if 10kg of Pu wasn’t enough to blow your town down, I’d love to see Orion. How big does an H2 parabola need to be to take the brunt of a 5kT blast. How heavy the structure?

  28. I don’t think “nuclear” and “really quickly” go in the same sentence, ever.

  29. BLA HA HA HA
    when PIGS FLY.
    NO MORE GEE men/women is space NONE!

  30. They’re turbo-pumps, not turbines for driving a generator. You’re not trying to get the maximum power out, you’re trying to pump the fluid.

    I think the flow-path is pretty straightforward: The upper part of the turbine is pumping cryogenic hydrogen. It goes to the bottom of the engine, cooling the nozzle.

    It then comes back up through the reactor, and as gas enters the lower, larger part of the turbine, where it generates enough power to run the pump.

    Then it’s back through the reactor to reach full temperature, and out the back end as exhaust.

  31. Yeah, I wish. Born too early: As a child I expected to be part of the colonization of space, but by the time I was heading to college things had just… petered out, and stalled for a couple generations.

    Now it’s heating up again, and I’m too damn old to be part of it. Just a few years from retiring, and starting to lose my engineering edge anyway. (Chemo didn’t help there.)

    All I can do now is cheer from the sidelines.

  32. Sure, they could. I think the big issue is that it wouldn’t be closed cycle, so that testing it on Earth would be really, really difficult. Mainly politically; Your test rocket would be firing nuclear waste plasma out the back end.

    Sure, you could fire the rocket into a buried chamber, and realistically contain it, but the politics would be almost impossible.

    That’s why I think it’s likely that open cycle nuclear rockets won’t be developed until space colonization has gotten far enough that people off Earth are making the decisions.

  33. Same drawbacks to the idea for a beamed power rocket right? Or solar thermal. Or even a LENR powered rocket.

    You still need a heating chamber and a nozzle that can handle the temps, which means that you will have the same erosion issues if you try to run higher temps, but if you don’t have higher temps you can’t get much more than ~1000 seconds Isp.

    To run higher ISP you need to start using electric/magnetic fields instead of physical chambers and nozzles.

    So… if the fusion boys think they can control their reacting mass with magnetic or electric fields, can’t the fission guys (who can at least get their reacting mass to actually react) do the same thing?

  34. You have a reference on that 175 W/kg number? I think you’re a bit too far over your skis there. Papers from NGRC from 2016 cite state-of-the art as 60 W/kg, with a goal of getting to 1.7x the state of the art, which would be about 100 W/kg. I’d be willing to believe that we’re there now.

    But given that we’re talking about a nuke that doesn’t yet exist, maybe higher specific power is warranted for our comparison. I’ll buy 1 MW with a specific power of 150 W/kg in the timeframe we’d be interested in. Let’s do the numbers again, with with 50 t payload and Isp=5000.

    Dry mass: 6.7 t solar + more thrusters + tanks ~= 9.7 t.
    Thrust = 60 mN/kW = 60 N
    Mass flow = 1.2 mg/s

    Kinda hard to figure out the delta-v. I suspect that it’s lower since you’re no longer completely limited by how long it takes to expend the prop. 7900 m/s?

    That would be 10.4 t of prop.
    Wet mass = 70.1 t.
    Burn time: 100 days. That’s pretty good.

    If delta-v is hard to compute, time-of-flight is even worse. It’s obviously more than 100 days, but I have no clue how much more. I’d guess is was less than 200 with the right window, but that’s about as far as I can go.

    So: with these parameters, about the same wet mass, but ~50 days shorter? That starts to look pretty good compared to NTR.

  35. ESA does have a plan to test the turboinductor with hot hydrogen from a non-radioactive source. Apparently they feel NTER allows for somewhat easier component level testing so they can work out the gremlins before they do the full integration. Everything before the turboinductor is a classic NERVA design in principle. But you can read it from the horse’s mouth, including their rough design for ground testing facilities.

  36. I’ve gone over the illustrated flow paths and now I am confused too. For one thing they appear to be feeding the turbines backwards.

    But yes, double expansion and triple expansion are used depending on the temperature and pressure of the supplied expanding gas (eg. steam). And this would also vary with turbine design (a more advanced turbine might still be efficient with a bigger expansion ratio) and no doubt also things like capital costs and weight requirements. Saving the cost and/or weight of a 3rd turbine might be worth losing a few % efficiency, or it might not. Do the math.

    And the points Brett brings are seem pretty solid to me too.

  37. I was trying to follow the illustrated flow paths… got confused. You have a good point but the turbines appear to be the same size. still I imagine you’re right. I thought triple expansion was the standard… but that might be kind of WW1 modern. I saw a youtube of an internal combustion engine that uses double expansion… I like pistons… I’m always amazed that people are able to design ice more complex than a barrel engine. even the Wankel is amazing.

  38. Do you think they’d have to build 50 before it worked? That’s the problem with nuclear s***. they have to bury it in Idaho after it breaks. Nobody can put a wrench on your turbo inductor after it runs.

  39. Throw enough money at it and it would work in 2 years. Yes you’d have to recreate the prototyping experience that retired

  40. The tungsten filament in an incandescent light bulb is good reference for trying to describe how hot they would have to run the fuel (average, not the 150% hot spot) in this reactor to gain much on LH2/LOX in terms of ISP. Tungsten filaments are very delicate, but they can operate for years at 2500 C in rare (near vacuum) argon. make the filament now a heterogeneous bar of W and hard UC or UO2, and flow 50kg/s H2 on it. The material is kind of like a modern cutting tool insert for a milling machine. It’s tough stuff but nothing is really tough at 2000C. At good ISP these Rockets have much less lifetime then the 1st jets… the fuel comes out the ass end. There is nothing you can do about it except run at a lower temp. You can try to make it not slump, clump and fail catastrophically, but instead erode predictably – best you can do. It’s a lot of trouble for an incremental Improvement in ISP, and they’re unlikely to have the resolve to iterate on the design until it works as well as SSME… are they going to build a series of 50 development builds to get it right? NERVA was canceled after maybe 6 builds. NTR is in the vein of chemical rockets and analogous to black powder before discovery that nitric acid could make high explosives out of any carbohydrate from rice to toluene

  41. If you are going to do nuclear thermal, and have the itch to be NERVA derivative, then frankly I find it hard to believe you can do much better than ESA’s NTER design. The turboinductor is a brilliant solution to the fuel melting problem for a solid fueled reactor, and in plasma mode starts edging up to pure electric plasma thrusters in performance. ESA never really went deep optimizing the parts after the turboinductor, so there is the potential for using VASIMR-like components for a magnetic nozzle and plasma accelerator.

  42. Looks like a double expansion turbine to me.

    Your hot compressed gas has a given amount of work it can do via expansion, but an efficient turbine design can only handle a given amount of expansion, which is less than what the gas can provide. So you have two (or more) stages, each turbine expands the gas by the optimum amount and you extract the most work from the system.

    Double expansion has been standard in steam engines since before they had turbines. Even the old 19th century steam piston engines did this.

  43. No. NTRs have nothing like that performance. The figures are that you can get an ISP of maybe 1000s with current level tech. Maybe that could be doubled? Let’s go with 2000s.
    There is no way you are getting a mass fraction of even an interstellar probe better than say 99%. And that’s assuming something like a frozen chunk of ice surrounded by a foil bag as being almost all of the launch mass. But I’ll use 99%.
    Rocket equation → deltaV = Isp.g.ln(m0/mf)
    = 2000s . 9.8 m/s . ln(99)
    = 90156 m/s

    Now that’s a nice delta V, but nothing close to interstellar probe speeds.

    The numbers of 2% of C etc may be from the Nuclear Pulse Engine AKA Orion (the original Orion not the fake new one). A totally different beast from the NTR.

  44. A bimodal engine that switches between high thrust and high thrust? I suspect you miswrote one of those descriptions.

  45. If you’ve ever had an engineering team in one site trying to replicate work done in another site you soon learn just how much hands on personal experience is needed in addition to all the reports, CAD, BOMs, even subassemblies being shipped over.

  46. Don’t tempt fate like that. Someone will take it as a challenge. Nextminute we get the “carbon neutral launch project” or something.

  47. If we are going to use NTP, it will never be for an orbital launch. Trying to convince anyone to allow a rocket that is propelled with radioactive vapor to fly through the earth’s atmosphere is going to be a hard sell.

    More likely if NTP gets used, it will be on a spacecraft constructed in orbit that is used for interplanetary transfers.

  48. When you refer to a solar arrays power to weight ratio, those figures are for an array operating around earth. The farther you go from the sun, the lower that ratio becomes. So a 100W/kg array around earth is probably something closer to a 60-70W/kg array around Mars, and well under 50W/kg around Jupiter. I am not sure the exact figures, but it does decrease substantially as you go further away.

  49. Timberwind show that with more modern technology you can get even better results. I think for a viable nuclear rocket program that we will have to mine Uranium or Thorium ore on the moon, and refine the ore and build the engines there. You would need a lot of infrastructure but there would be a lot less political head wind there. No Nimby.

  50. Nuclear thermal rockets are not drop-in replacements for normal rockets, there are important differences. They run on hydrogen mono-propellant, so tank volume will be very high. Also, they only make sense when departing from some place at which oxygen is not cheap. On the surface of Earth or Mars, oxygen is super cheap. This favors their use in 3rd stages, for departing from Earth orbit or 2nd stage departing Mars orbit, or uni-stage landing upon and departing the Moon.

    Discarding the nuke immediately after the engine burn saves a lot of weight in shielding.

    Of course, SpaceX is arguing that a 3rd stage for Earth departure is not needed, rather refueling the 2nd stage is the better solution.

    It’s important to understand that for Mars departure, each kg of ISRU H2 costs exactly the same as 9 kg of H2-O2 bi-propellant (i.e. 1kg H2, 8 kg O2, they are produced together from 8 kg of water), and the bi-propellant can carry more payload. Furthermore, CO2 from the atmosphere is cheaper than water; when CO2 is combined with water in the right machine, methane-oxygen bi-propellant (CH4 + O2) comes out, which is cheapest of all, for a given payload.

    Nuclear-thermal works with the vision of the orbiting mother-ship that travels between Earth orbit and Mars orbit (like the NASA Lunar Gateway idea, and Lockheed-Martin’s Mars Basecamp). But as soon as someone demonstrates refueling in LEO and propellant production on Mars, nuclear thermal rockets get a lot less interesting.

  51. I can think of a couple possible reasons:

    1) They used a “stock” pump, and it took two of them to handle the flow.
    2) The consequences of the pump failing in mid-burn are awful enough that it was worth having redundant pumps.

  52. Nuclear thermal is yesterday’s tomorrow. Sure, the performance is better than chemical, but is it cost effective relative to chemical at this point?

    We’d be far better off at this point using reusable chemical rockets to reach orbit, and then once there using a much higher performing nuclear option, like PUFF. That’s where the effort should be going: REALLY high performance nuclear rockets that can be used once in space, not moderately high performance nuclear rockets hobbled by the need to be closed cycle for use in Earth’s atmosphere.

  53. “Nuclear-thermal rockets are already obsolete. Nuclear-electric has 5 times the performance (Isp)…”

    Yes, high specific impulse, but crazy-small thrust. And you need that to get from LEO to escape in short times (as well as orbital insertion at your destination), and not spend weeks spiraling out slowly through the VanAllen belts, instead of cutting quickly across them.

  54. Get back to me, when they actually build and test a prototype, as in the NERVA days…

    The anti-nuclear folks who came out in droves over Cassini’s simple RTG, will go utterly insane over this, today.

  55. Folks no need to fight between high thrust/low(er) ISP nucelar propulsion and low thrust/high ISP nuclear propulsion.

    Make a Bimodal nuclear engine and use the high thrust mode when you are deep in a gragity well (hello Oberth effect) and then switch to high thrust to cruise.

  56. Nuclear-thermal is “self cooling”, because you are flowing cryogenic hydrogen through the reactor, and then out the nozzle. Nuclear-electric does need radiators to dump heat from whatever fluid cycle is running your generator. How big they have to be depends on the high and low temperatures in the cycle, and output power of the reactor.

    Radiators for the NASA Kilopower reactor, which as the name indicates is sized for 10 kW output, unfolds like an umbrella.

  57. State of the art space solar panels are producing 175 W/kg, and prototypes are pushing that higher. The ISS solar array wings (it has 8) are 400 m^2 each. State of the art cells produce 400 W/m^2 using triple-layer cells @ 30% efficiency. It is reasonable to have 6 such wings in a hexagonal pattern around a tank and engine core, but pivoting so they can always face the Sun. This gives you 6 x 400 x 400W = 960 kW, without pushing technology beyond what already has flown. With some push, I think we can get to 2 MW, but beyond that sheer size starts to become impractical.

    Note: ISS arrays were 66 W/kg, but they were single layer silicon @ 12% efficiency (1980’s technology). Most of the increase is simply from higher efficiency.

  58. We planted heat probes into the Moon during the Apollo missions. It turns out about a meter down, the temperature hardly varies across the day/night cycle. Finely powdered rock separated by vacuum are an excellent insulator.

    The bigger problem will be getting rid of waste heat generated by people, lighting, and equipment. The ISS needs an active cooling system with radiator panels to dump excess heat. They are the sets of three white panels sticking out of the truss near the center. The single radiators sticking out from the solar arrays are to cool the batteries which power the station during the 40% of the orbit in the Earth’s shadow.

    Thermal management is definitely an important subsystem in any space project, but whether you need heating or cooling isn’t necessarily obvious.

  59. Nuclear Thermal Rockets may be the only way to get astronauts to the orbit of Mercury.

    If such rockets ever become operational then Hohmann launch windows to the planet Mercury should be available at least– three times a year– which would make Mercury much easier to colonize than Mars.

  60. It’s not that simple. Let’s take a couple of illustrative examples for a 50 t payload mission:

    Delivered power: 500 kW (pretty big right now).
    Solar specific power: 100 W/kg (not quite there, but close…).
    Thrust @ 60 mN/kW = 30 N.
    Isp: 5000 s.
    Mass flow = T/(Isp*9.807) = 6.1E-4 kg/s
    Dry mass: 5 tonnes PV + prop tanks + overhead–call it 8 tonnes.
    Delta-v to Mars capture: 5780 m/s (spiral delta-v ~= difference in orbital speeds) + 3200 m/s to earth escape = 8980 m/s.
    Prop required: 11.7 t.
    Wet Mass: 69.7 t.
    Time to expend prop: 11.66E3 / 6.1E-4 = 221 days.

    NTR (I’m going to use the TIMBERWIND 45 as an example):
    Delivered power: unknown, but probably > 500 MW.
    Thrust: 441.3 kN
    Isp: 1000 s
    Mass flow: 45 kg/s (hence the TIMBERWIND 45!)
    Engine dry mass: 1.5 t engine + prop tanks + overhead–call it 5 tonnes
    Delta-v to Mars capture (110-day transit time): 7720 m/s
    Prop required: 65.8 t
    Wet mass: 120.8 t.

    So NTR gives you half the transit time but requires 75% more mass to LEO.

    SEP is ultimately power- and mass-flow-limited. NTR has plenty of power, can do impulsive burns, but isn’t as efficient. Which one is better depends on what you’re optimizing for.

  61. That depends on where you are in the solar system. Eventually there will be installations in the belt, and orbiting Jupiter, manned or not. Even on the moon, waste heat will be vital in warming underground installations, and surface installations during lunar night. I suppose there will be heatsink “farms” where there will be deep tunnels to dump heat in, when it’s in surplus.

  62. It depends on the mission. If you want to move a lot of weight like a manned mission to Mars a nuclear rocket maybe the best choice. There hasn’t been a lot of development for Solar-Thermal but I think it may have a lot of potential.

  63. That why engineers get paid the big bucks.
    If burning stacks of $10,000 bills in a wood oven would yield 5000sec, I would say forget the NTR(open or closed.) and go with that.

  64. Well, I thought an NTR could reach velocities of 2% of c(“c” is the speed of light). And eventually, more advanced NTR designs could reach 4% of c.
    That means a probe could hypothetically reach Proxima Centauri in about 115 years from launch, for comparison, Voyager has been active for 42 years, and should remain active until 2025(which would make it 48 years old). Obviously, the people who launch the Centauri probe won’t be the same people who see the results it sends back, but it’s doable.

  65. If you’re going to do a NTR, you might as well go all the way and go open cycle.
    5000sec would be very useful.

  66. What you are referring to as “waste heat” is actually the point here…. propellant cooled. I agree though, it is ‘tarded. Don’t be too concerned about LEU vs HEU and size or spectrum…. it will certainly run to failure just fine.

  67. On a mass basis, it works out to Jupiter, and in fact we have a solar-powered spacecraft (Juno) orbiting Jupiter now. The Dawn spacecraft used solar-powered ion propulsion very successfully in the Asteroid Belt, until it ran low on fuel.

    Solar-thermal potentially can work even farther out, because concentrating solar reflectors can be exceedingly thin, and thus lightweight.

  68. Shoot, BWXT (B&W) spent $500M on a little PWR that never got built in 4 years. Will BWXT enjoy this gravy? Yes. Brian’s probabilities 1 in 5 for flying and 1 in 2 for ground test are generous, but of course ground testing may actually happen, eventually. 500MW unshielded reactor with LH2 flushing through it… where are the greentards tring to shut this down?

    My position, which is actually quite elaborate, is that NTP is the worst idea ever tested. I do not wish them luck, and they need more than wishes.

  69. Not really. NERVA was done in the 1970’s. All the people who did the work are retired or dead. Sure, you have technical reports, but that’s not the same as having working experience.

  70. Nuclear thermal motors was basicly in operational state of development, NASA can develop new nuclear thermal motors really quickly.

  71. Why would NASA need a 500 MW reactor for deep space use? Mars lander? Yes, nuclear thermal rockets have a higher ISP than any chemical rocket, but you only need that much thrust to lift out of a gravity well.
    I’d think our money(taxes) would be better spent on high power density reactors, and energy conversion systems(heat engines) to power electromagnetic drives like VASIMR, and to make outer system missions more practical. You could use the drive to get to Ceres, and then power a station with the reactor, and the heat engine.
    Seems to me that low enrichment reactors will be inherently more massive, since they will have to operate in the thermal spectrum, and will have to carry along a moderator, not to mention all that U238. Yes, you could use water as a moderator, and a heat transfer fluid, but then the high pressures would mean the reactor vessel would be heavy as hell.
    Of course a high enrichment fast reactor can also breed much better, and be less negatively effected by neutron poison fission daughters. There’s no telling how high a burn rate you could get with a molten salt version. I suspect it would be limited by the life of the reactor vessel, which would be long since it could operate at near vacuum pressure.
    Of course, continuing the SLS is sheer lunacy. That money might as well be flushed down a toilet here on earth.

  72. This is promising, but I suspect it is a paper rocket design, just like all the paper reactor designs out there. Something to train new nukes, but will never see launch. JIMO anyone?

  73. Nuclear-thermal rockets are already obsolete. Nuclear-electric has 5 times the performance (Isp), and solar-thermal has the same performance, without the overhead mass, risk, and fear associated with anything nuclear.

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