New nuclear engine concept could help realize 3-month trips to Mars

New nuclear engine concept cou...
The concept engine is twice as efficient as chemical rockets
The concept engine is twice as efficient as chemical rockets
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The concept engine is twice as efficient as chemical rockets
The concept engine is twice as efficient as chemical rockets

Seattle-based Ultra Safe Nuclear Technologies (USNC-Tech) has developed a concept for a new Nuclear Thermal Propulsion (NTP) engine and delivered it to NASA. Claimed to be safer and more reliable than previous NTP designs and with far greater efficiency than a chemical rocket, the concept could help realize the goal of using nuclear propulsion to revolutionize deep space travel, reducing Earth-Mars travel time to just three months.

Because chemical rockets are already near their theoretical limits and electric space propulsion systems have such low thrust, rocket engineers continue to seek ways to build more efficient, more powerful engines using some variant of nuclear energy. If properly designed, such nuclear rockets could have several times the efficiency of the chemical variety. The problem is to produce a nuclear reactor that is light enough and safe enough for use outside the Earth's atmosphere – especially if the spacecraft is carrying a crew.

According to Dr. Michael Eades, principal engineer at USNC-Tech, the new concept engine is more reliable than previous NTP designs and can produce twice the specific impulse of a chemical rocket. Specific impulse is a measure of a rocket's efficiency.

To fuel the concept, UNSC-Tech uses a Fully Ceramic Micro-encapsulated (FCM) fuel to power the engine's reactor. This fuel is based on High-Assay Low Enriched Uranium (HALEU), which is derived from reprocessed civilian nuclear fuel and is enriched to between 5 and 20 percent – greater than that of civilian reactors and less than that of naval reactors. The fuel is then encapsulated into particles coated with zirconium carbide (ZrC).

The company claims that this fuel is much more rugged than conventional nuclear fuels and can operate at high temperatures. This produces safer reactor designs and a high thrust and specific impulse that could previously only be obtained with highly-enriched uranium. In addition, such fuel can be produced with current supply chains and manufacturing plants.

It is hoped the new concept could lead to nuclear engines that reduce deep space mission times drastically, with a crewed mission to Mars arriving in as little as three months. Beyond that, the concept is aimed at a commercial market as well as with NASA and the US Department of Defense, allowing for more ambitious private missions.

"Key to USNC-Tech’s design is a conscious overlap between terrestrial and space reactor technologies," says Dr. Paolo Venneri, CEO of USNC-Tech. "This allows us to leverage the advancements in nuclear technology and infrastructure from terrestrial systems and apply them to our space reactors."

The project is part of a study managed by Analytical Mechanics Associates (AMA) for the space agency regarding NTP flight. USNC-Tech says the concept was "designed to enable a successful near-term system demonstration and reduce barriers to full-scale deployment," but we suspect a sixth month round trip to Mars is probably still some way off.

Source: Ultra Safe Nuclear Technologies

Does twice the efficiency translate into twice the thrust force or twice the duration that the engine runs?
Martin Zitter
This concept might work well as a "cycler" with two of them remaining in space and orbiting between Mars and Earth every 26 months delivering payloads from LEO to LMO and back.
There's nothing to do on Mars and nowhere to go except back home.
I think it would be a 1-way trip to dullsville followed by some stupid, ghastly demise.
Is it safe enough not to scatter lethal radiation if it re-enters and crashes? Because my impression was that is the current standard. If you could guarantee that a running reactor would never land, that might be safe enough.
Perhaps we can use a version of it in a lead box to generate some electricity for us in remote areas.
We need Warp drives !!
The problem with space-based reactors has always been shielding human passengers from the reactor. There typically needs to be a massive radiation shield and astronauts have to be located long distances away from a reactor, often on a giant, awkward boom. The article says nothing about that critical issue, though the picture makes it look like the reactor and nozzel are quite close together and perhaps some kind of crew area is right on top of that. I doubt that would be safe. Putting a reactor in space has never been the main problem. Having it not kill human passengers has been.
@Heckler -- none of the above in this case. The article mentions this engine has double the specific impulse compared to chemical engines. Specific impulse is the change in momentum that a particular combination of propellant and engine provides. One way to get a higher specific impulse is to toss the same stuff out the back faster. Another is to toss a larger amount of something else at the same speed. For efficiency improvements in rockets, it's usually about tossing stuff out faster. Given that the nuclear fuel isn't going to be gone in a relatively short period of time, I'm assuming that this engine operates for an extended period, tossing a relatively small amount of working material at much higher speeds than chemical engines do. Double the specific impulse is really good, but I believe they'll need to get to 4-10x to challenge well known chemical rocket technology.
I cannot believe how stupid and pointless this idea is, except within a strange sub-community that fails to reflect on the stupidity and pointlessness of space exploration at this critical point in human evolution.
Mark Smith
Why not use Liquid Thorium?1000 times the power. One tenth the weight. MUCH more safe. Smaller rocket. Lower cost. More power. Why do they keep going back to outdated uranium?