A nuclear fission fragment rocket engine (FFRE) that is exponentially more propellent efficient than rocket engines currently used to power today’s space vehicles and could eventually achieve very high specific impulse (>100,000 sec) at high power density (>kW/kg). A new NASA NIAC (NASA Innovative Advanced Concepts) project is creating a buildable near term design for a nuclear fission fragment rocket. It would enable manned mission to Mars with 90 day travel times.
The fission fragment system would give experience in a technology which could eventually enable interstellar rockets with speeds of 10% of the speed of light.
A mature and advanced fission fragment rocket using hundreds of tons of fissile fuel and a 200 gigawatt reactor could have a design that could reach about 10% of light speed.
The proposed designs for Fission Fragment Rocket Engines are prohibitively massive, have significant thermal constraints, or require implementing complex designs, such as dusty plasma levitation, which limits the near-term viability. NASA NIAC researchers propose to develop a small prototype low-density nuclear reactor core and convert the nuclear energy stored in a fissile material into a high velocity rocket exhaust and electrical power for spacecraft payloads.
The key improvements over previous concepts are:
1. Embed the fissile fuel particles in an ultra-low density aerogel matrix to achieve a critical mass assembly
2. Utilize recent breakthroughs in high field, high temperature superconducting magnets to constrain fission fragment trajectories between moderator elements to minimize reactor mass.
The aerogel matrix and high magnetic field (B>20T) allows for fission fragments to escape the core while increasing conductive and radiative heat loss from the individual fuel particles. NIAC work will provide detailed mission analysis of fast transit to SGL for direct imaging and high-resolution spectroscopy of a habitable exoplanet at a distance of up to 100 light years. The FFRE propulsion system could provide delta-V to reach the SGL in less than 15yrs and provide the slowdown and maneuvering capability at SGL. The telescopes would act as a single pixel detector while traversing the Einstein Ring region, building an image of the exoplanet with enough resolution to see its surface features and signs of habitability.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.
A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.
Hi Brian
To get to 0.1 c using a FFRE will take quite a mass-ratio. Of course it could be a booster for some other technique.
Thanks for the info. 3-5% lightspeed is more achievable with still very advanced FFRE. The 10% needs a lot of multi-staging.
Also they need a magnetic drag sail to decelerate at their destination so they don’t have to burn fuel to do so.
A gravitational focus mission intended to look at planets would need to have quite a bit of delta-V available for position control.
While a planetary “image” at the start of usable gravitational focus would be about 2.5km for an Earth sized planet at Alpha Centauri, that image would be traveling around a 60 km ellipse due to its orbital motion, you’d have to track that, too. So your probe has to find the exact focal point, and then track the orbital motion while scanning the image. All in all a LOT of moving around.
A point commonly ignored in solar gravity telescope discussions.
Solar gravity telescopes are so good you need to take into account exoplanetary parallax!
Which means a lot of space delta-V is required. I imagine something lasting in the long term would be enough, like ion thrusters, but you indeed need the power suppyl and thrusters to move your telescope several miles in the course of some weeks or months.
A design buildable “near term” by NASA? That’s funny.
Seriously though, kudos to NASA. But NASA’s next smart step is give the project to Spacex.
The foil concept would actually have some low double digit fraction of the fission product power pumping the cavity; useful for laser. The aerogel stuff not so much worky work. These low density cores would need to be very “macroscopic” to say the least. A PVD or “foil” and quartz array scales to whatever size would buckle.
The bar for NASA pubs isn’t so high nowadays. This was one of my favorites: https://www.nextbigfuture.com/2017/04/continuous-electrode-inertial-electrostatic-confinement-fusion.html
Prediction: chemical rockets will be dead except for satellite, space station and lunar missions by the end of the decade. This means, effectively, that a chemical rocket will never be used to transport humans to Mars or beyond. Some form of atomic rockets will be used instead.
The problems of feeding, cosmic shielding, and simply maintaining the human body in a weightless environment is too difficult, and trying to provide artificial gravity requires such a large payload that you need impractical refueling stations along the way in multiple locations, which is too costly and inefficient for chemical rockets. Also, having to wait for the optimal timing to go, or more importantly, return from, Mars is too long: 26 months. This delay is a near certain setup for catastrophic failure for a human crew.
At the same time, we’ve just about reached the limit of useful and interesting (interesting = funded) robotic missions to Mars or even the Moon. The push by the 2030s will be for manned missions. Yes, it could theoretically come sooner than that, but there are just too many problems on Earth to prioritize that like back in the headlong 1960s. And Elon Musk isn’t going to make it to Mars, barring some breakthrough life extension/youth extension. He’ll be 60 in 2031, which is just too old for the first human powered flight for non-NASA astronauts, even on his own dime for a then-trillionaire (maybe – but a lot has to go right with his future projects first). Musk has a history of missing deadlines, and the ultimate deadline is coming faster than he and the world is willing to admit.
The Starship plan now is for 8X fuel transfer for a Moon trip and return: https://www.teslarati.com/spacex-starship-moon-landing-orbital-refueling-nasa/. This is a lot harder than it sounds, and very expensive too. By the time this is ready, even duel-propulsion rockets with chemical means to Earth orbit and atomic propulsion beyond, will be more practical. At some point in the mid to late 2020s, this will become too obvious to ignore, and NASA and other space agencies will reorient their limited budgets to that goal. Space agencies, unlike specific humans like Musk, have an unlimited timeframe. They have limited budgets and political will, however, so they can’t go heavily into two competing major visions.
Something from left field…today, phys.org had an article with the following title:
“Researchers develop neutron-shielding film for radiation protection.”
Yes…I said “film.”
This MXene-Boron carbite composite is 1,000 times thinner than other shielding.
Now, if I were to spray a thin film of fissile material on this…might I have a rad-sail that can ALSO use sunlight and magnetic fields for a three-fer?
More on today’s phys.org…
“New technique could speed up the development of acoustic lenses, impact resistant films and other futuristic materials.”
Pretty impressive. Really only good for thermal neutrons, but still, impressive.
90 days to Mars would be nice, but I’d rather spend 180 days in a Starship than 90 in a Dragon capsule.
It sounds like one Starship launch could re-fill multiple FF-plasma engines – which would be a big advantage over Starship, assuming the “Mars ship” can be reused.
However, it looks like 10 tons of Lithium propellant is needed – presumably that’s for a one way trip to Mars? So if they wanted to return to Earth, 100% of the payload would be needed for the return propellant. And I don’t see a Mars lander in that “Mars ship”, so that’d have to be pre-positioned and fueled and able to rendezvous with the FF ship.
Not gonna happen until the Belters are making indigenous propulsion.
Interstellar? I should live so long.
I wish these advanced propulsion schemes had mission concepts with more payload and larger rockets. For comparison.
What about 50 or 100 metric tons to Mars? Can we just attach 5 of these together? Etc
The Orion Nuclear Fission Pulse Propulsion project had several different mission schemes and payloads… including on with gigatons of payload.
There is no need to move cargo to Mars quickly. If you want to get there quickly then in orbit refueling will work just fine.