NASA - Bimodal NTP/NEP with a Wave Rotor Topping Cycle

[Astronuc]

New Class of Bimodal NTP/NEP with a Wave Rotor Topping Cycle Enabling Fast Transit to Mars​

https://www.nasa.gov/directorates/spacetech/niac/2023/New_Class_of_Bimodal/

Nuclear Thermal Propulsion (NTP) is identified as the preferred propulsion technology for manned missions throughout the solar system. The state-of-the-art NTP cycle is based on solid core Nuclear Engine for Rocket Vehicle Application (NERVA) class technology that is envisioned to provide a specific impulse (Isp) of 900 seconds doubling chemical rocket performance (450 seconds). Even with this impressive increase, the NTP NERVA designs still have issues providing adequate initial to final mass fractions for high DeltaV missions. Nuclear Electric Propulsion (NEP) can provide extremely high Isp (>10,000 seconds) but with only low thrust and limits on mass to power ratios. The need for an electric power source also adds the issue of heat rejection in space where thermal energy conversion is at best 30-40% under ideal conditions.

A novel Wave Rotor (WR) topping cycle is proposed that promises to deliver similar thrust as NERVA class NTP propulsion, but with Isp in the 1400-2000 second range. Coupled with an NEP cycle, the duty cycle Isp can further be increased (1800-4000 seconds) with minimal addition of dry mass. This bimodal design enables the fast transit for manned missions (45 days to Mars) and revolutionizes the deep space exploration of our solar system.

Ryan Gosse, University of Florida, Gainesville, FL

NASA has revealed plans to create a nuclear-powered rocket that could send astronauts to Mars in just 45 days.

The agency, which has partnered with the Pentagon’s Defense Advanced Research Projects Agency (DARPA) to design the rocket, announced on Tuesday (Jan. 24) that it could build a working nuclear thermal rocket engine as soon as 2027.

NASA’s current rocket systems (including the Space Launch System which last year sent the Artemis 1 rocket on a historic round-trip to the moon) are based on the century-old, traditional method of chemical propulsion — in which an oxidizer (which gives the reaction more oxygen to combust with) is mixed with flammable rocket fuel to create a flaming jet of thrust.

https://www.sciencealert.com/new-nasa-nuclear-rocket-plan-aims-to-get-to-mars-in-just-45-days

As part of the NASA Innovative Advanced Concepts (NIAC) program for 2023, NASA selected a nuclear concept for Phase I development. This new class of bimodal nuclear propulsion system uses a "wave rotor topping cycle" and could reduce transit times to Mars to just 45 days.

The proposal, titled "Bimodal NTP/NEP with a Wave Rotor Topping Cycle," was put forward by Prof. Ryan Gosse, the Hypersonics Program Area Lead at the University of Florida and a member of the Florida Applied Research in Engineering (FLARE) team.

Waiting to see what that looks like in practice.

Edit/update: Not to be confused with NASA/DARPA DRACO program
https://www.nasa.gov/press-release/nasa-darpa-will-test-nuclear-engine-for-future-mars-missions
https://www.darpa.mil/news-events/2023-01-24

 

[anorlunda]

The need for an electric power source also adds the issue of heat rejection in space where thermal energy conversion is at best 30-40% under ideal conditions.

That sounds challenging. Here on Earth, we can always think of many ways to accomplish cooling. But on a spacecraft, radiative cooling is the only method I can think of.