NASA Administrator Bill Nelson announces at AIAA SciTech that the agency is partnering with DARPA on nuclear thermal propulsion (NTP) development, with the goal of launching and demonstrating an NTP system as soon as 2027.
Nelson doesn't provide any further details on this partnership, but the session is now shifting to a panel with NASA Deputy Admin Pam Melroy and DARPA Director Stefanie Tompkins.
NASA will lead the design of the nuclear engine itself, which will be integrated into a DARPA experimental spacecraft. Spacecraft would operate at a minimum altitude of 700 km, maybe as high as 2,000 km, says Melroy.
Jan 24, 2023RELEASE 23-012NASA, DARPA Will Test Nuclear Engine for Future Mars MissionsNASA and the Defense Advanced Research Projects Agency (DARPA) announced Tuesday a collaboration to demonstrate a nuclear thermal rocket engine in space, an enabling capability for NASA crewed missions to Mars.NASA and DARPA will partner on the Demonstration Rocket for Agile Cislunar Operations, or DRACO, program. The non-reimbursable agreement designed to benefit both agencies, outlines roles, responsibilities, and processes aimed at speeding up development efforts. “NASA will work with our long-term partner, DARPA, to develop and demonstrate advanced nuclear thermal propulsion technology as soon as 2027. With the help of this new technology, astronauts could journey to and from deep space faster than ever – a major capability to prepare for crewed missions to Mars,” said NASA Administrator Bill Nelson. “Congratulations to both NASA and DARPA on this exciting investment, as we ignite the future, together.”Using a nuclear thermal rocket allows for faster transit time, reducing risk for astronauts. Reducing transit time is a key component for human missions to Mars, as longer trips require more supplies and more robust systems. Maturing faster, more efficient transportation technology will help NASA meet its Moon to Mars Objectives.Other benefits to space travel include increased science payload capacity and higher power for instrumentation and communication. In a nuclear thermal rocket engine, a fission reactor is used to generate extremely high temperatures. The engine transfers the heat produced by the reactor to a liquid propellant, which is expanded and exhausted through a nozzle to propel the spacecraft. Nuclear thermal rockets can be three or more times more efficient than conventional chemical propulsion.“NASA has a long history of collaborating with DARPA on projects that enable our respective missions, such as in-space servicing,” said NASA Deputy Administrator Pam Melroy. “Expanding our partnership to nuclear propulsion will help drive forward NASA's goal to send humans to Mars.”Under the agreement, NASA’s Space Technology Mission Directorate (STMD) will lead technical development of the nuclear thermal engine to be integrated with DARPA’s experimental spacecraft. DARPA is acting as the contracting authority for the development of the entire stage and the engine, which includes the reactor. DARPA will lead the overall program including rocket systems integration and procurement, approvals, scheduling, and security, cover safety and liability, and ensure overall assembly and integration of the engine with the spacecraft. Over the course of the development, NASA and DARPA will collaborate on assembly of the engine before the in-space demonstration as early as 2027. “DARPA and NASA have a long history of fruitful collaboration in advancing technologies for our respective goals, from the Saturn V rocket that took humans to the Moon for the first time to robotic servicing and refueling of satellites,” said Dr. Stefanie Tompkins, director, DARPA. “The space domain is critical to modern commerce, scientific discovery, and national security. The ability to accomplish leap-ahead advances in space technology through the DRACO nuclear thermal rocket program will be essential for more efficiently and quickly transporting material to the Moon and eventually, people to Mars.”The last nuclear thermal rocket engine tests conducted by the United States occurred more than 50 years ago under NASA’s Nuclear Engine for Rocket Vehicle Application and Rover projects.“With this collaboration, we will leverage our expertise gained from many previous space nuclear power and propulsion projects,” said Jim Reuter, associate administrator for STMD. "Recent aerospace materials and engineering advancements are enabling a new era for space nuclear technology, and this flight demonstration will be a major achievement toward establishing a space transportation capability for an Earth-Moon economy.”NASA, the Department of Energy (DOE), and industry are also developing advanced space nuclear technologies for multiple initiatives to harness power for space exploration. Through NASA’s Fission Surface Power project, DOE awarded three commercial design efforts to develop nuclear power plant concepts that could be used on the surface of the Moon and, later, Mars.NASA and DOE are working another commercial design effort to advance higher temperature fission fuels and reactor designs as part of a nuclear thermal propulsion engine. These design efforts are still under development to support a longer-range goal for increased engine performance and will not be used for the DRACO engine. To learn more about STMD, please visit:https://www.nasa.gov/spacetech-end-
Artist concept of Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will demonstrate a nuclear thermal rocket engine. Nuclear thermal propulsion technology could be used for future NASA crewed missions to Mars.Credits: DARPA
QuoteArtist concept of Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will demonstrate a nuclear thermal rocket engine. Nuclear thermal propulsion technology could be used for future NASA crewed missions to Mars.Credits: DARPA
Quote from: FutureSpaceTourist on 01/24/2023 02:56 pmQuoteArtist concept of Demonstration for Rocket to Agile Cislunar Operations (DRACO) spacecraft, which will demonstrate a nuclear thermal rocket engine. Nuclear thermal propulsion technology could be used for future NASA crewed missions to Mars.Credits: DARPANo aerobraking possible with that artist's renderingThey just threw away 7km/sec of deltaV. "three times as efficient" can't possibly make up for throwing away 7km/sec of deltaV.I bet the thermal protection system of Starship weighs less than the NTR engine + shielding. There's little or no fuel needed for aerobrakingNTR are obsolete with cheap LEO refueling if there is any aerobraking capability on the far end. Even a (rare) NTR mission without atmosphere on the far end can barely compete with a fully-refueled Starship on a GTO ellpitical orbit that benefits from the Oberth effect.If you think you can develop an NTR that has aerobraking, you can't. Where are you going to test the thermal protection system? I don't think Earth really wants an oopsie it burnt up on a nuclear rocket.Refueled chemical architectures with aerobraking make NTR obsolete.A rocket needs around 2000+ ISP to make up for the loss of aerobraking on any mission that has an atmosphere at the end.
As for aerobraking, this is just a demo. You could always add an aeroshell etc. after sim and chamber test.
1. pretend you're not already helping pay for a vehicle in dev that could get you to Mars in 3-5 months.2. baseline an opposition class mission w/ obscenely long transit times3. pitch new tech for speed when it won't speed up either class of mission relative to vehicle in (1)That said, woohoo for nuclear propulsion tests in space
If you don’t care about starting mass, a good chemical stage has higher single stage delta-v than nuclear thermal. That high dry mass sucks.Heck, for some trajectories, a chemical stage can outperform the prototype nuclear thermal rocket stage even if you care about starting mass. Dry mass is a b****.
Quote from: HusyeltUnfortunately or fortunately, NASA will happily wait for this to be developed if it means the first crewed mission to Mars takes 1-2 months shorter travel time.It won't, though...Very hard to beat refueling + aerobraking.You're looking at the equivalent of LEO+10-11km/s just to match something Starship-ish to LMO at 80-150 days (depending on synod), to say nothing of the return trip. And it's rapidly diminishing returns to go faster
Unfortunately or fortunately, NASA will happily wait for this to be developed if it means the first crewed mission to Mars takes 1-2 months shorter travel time.
...an NTR stage can dramatically improve its mass fraction using much larger tanks that can be launched empty and filled in orbit.
There is no physical mechanism to prevent an NTR stage utilising aerobraking. Not even on Mars, as there are currently 4 vehicles on Mars that carried RTGs, and all entered using Aerobraking, so clearly Planetary Protection is not an impediment.
Quote from: edzieba on 01/25/2023 07:48 am...an NTR stage can dramatically improve its mass fraction using much larger tanks that can be launched empty and filled in orbit.But how does that differ from other tanker scenarios, for other rockets?NASA touts NTR for quick and efficient transport to Mars. Transport from Mars isn't touted quite as much. An NTR wouldn't launch crews from Mars, after all; it orbits. To get your best NTR efficiency / mass fraction, chemical rockets would need to deliver return ISRU LH2, filling the NTR in Mars orbit. That means a parallel ISRU LH2 infrastructure on Mars or on a Martian moon, alongside the existing SpaceX methalox infrastructure, and perhaps ASCENT infrastructure.Worth the trouble?Image: NTR over the years. Borowski et al. 2013.Refs.Borowski, S.K., McCurdy, D.R. and Burke, L.M., 2013. The Nuclear Thermal Propulsion Stage (NTPS): A Key Space Asset for Human Exploration and Commercial Missions to the Moon. In AIAA SPACE 2013 Conference and Exposition (p. 5465).
Quote from: edzieba on 01/25/2023 07:48 amThere is no physical mechanism to prevent an NTR stage utilising aerobraking. Not even on Mars, as there are currently 4 vehicles on Mars that carried RTGs, and all entered using Aerobraking, so clearly Planetary Protection is not an impediment.Not true, for many reasons:1. A rocket with large tanks is an elongated rocket needs to look something like a Starship. The RTGs you are talking about were classic cone heat shields. So you have to have the same amount of testing as Starship to get aerobraking to work. It hasn't been done before
From what i read they aim for a rather low T/W ratio (2-3) and an ISP of around 900 which is not much better than chemical propulsion ( i remember Kirk Sorensen wrote a good article on the topic ).
Even lightly loaded NTR is better than Hydrolox, its when you up payload that they really shine.
Go the other way and test aerobraking at Venus. Plenty of atmosphere to play with and a good opportunity to drop some satellites into orbit there.
Quote from: TrevorMonty on 01/26/2023 06:19 pmEven lightly loaded NTR is better than Hydrolox, its when you up payload that they really shine.If payload were the driving problem, that might be relevant. But what missions are payload-prohibited, e.g., with methalox Starships and ASCENT engines?Moving forward, ISRU can conjure bulk propellant outside Earth's gravity well, with definite paths to: 1. ISRU hydrolox on the Moon,2. ISRU methalox on Mars,3. ISRU LOX in VLEO, and4. ISRU ASCENT in VLEO, on Mars, and in Mars orbit.-- And ASCENT ion drive clusters can push mass with much higher Isp than NTR, at ~ 1500 s. Maybe creativity and money should be applied to such modern bulk ISRU propulsion scenarios, instead of an idea that's been searching for justification -- and reliable lightweight implementation -- since the 1940s.
