A nuclear thermal rocket has double the propulsion efficiency of the Space Shuttle main engine, one of the hardest-working standard chemical engines of the past 40 years. That capability makes nuclear thermal propulsion ideal for delivering large, automated payloads to distant worlds. (video)
- BWX Technologies, Inc. (NYSE:BWXT) announced that its BWXT Nuclear Energy, Inc. subsidiary has been awarded an $18.8 million contract from NASA to initiate conceptual designs for a nuclear thermal propulsion reactor, using LEU, in support of a possible future manned mission to Mars.
- The scope of the contract includes initial reactor conceptual design, initial fuel and core fabrication development, licensing support for initial ground testing, and engine test program development. Work under the contract is expected to continue through 2019.
Part of NASA’s Game Changing Development Program, the Nuclear Thermal Propulsion (NTP) project could significantly change space travel, largely due to its ability to accelerate a large amount of hydrogen or other propellant out of the back of a rocket at very high speeds, resulting in a very efficient, high-thrust engine.
“As we push out into the solar system, nuclear propulsion may offer the only truly viable technology option to extend human reach to the surface of Mars and to worlds beyond,” said Sonny Mitchell, Nuclear Thermal Propulsion project manager at NASA Marshall.
“We’re excited to be working on technologies that could open up deep space for human exploration.”
An NTP system can cut the voyage time to Mars from six months to four and safely deliver human explorers by reducing their exposure to radiation. That also could reduce the vehicle mass, enabling deep space missions to haul more payload.
“BWXT is extremely pleased to be working with NASA on this exciting nuclear space program in support of the Mars mission,” said Rex D. Geveden, BWXT’s President and Chief Executive Officer.
“We are uniquely qualified to design, develop and manufacture the reactor and fuel for a nuclear-powered spacecraft. This is an opportune time to pivot our capabilities into the space market where we see long-term growth opportunities in nuclear propulsion and nuclear surface power.”
Nuclear Thermal Propulsion (NTP) is an attractive option for in-space propulsion for exploration missions to Mars and beyond. NTP offers virtually unlimited energy density and specific impulse roughly double that of the highest performing traditional chemical systems. Plus, it doesn’t involve the weight of chemical fuels including oxidizers.
As missions aim for targets farther out into the solar system, nuclear propulsion may offer the only viable technological option for extending the reach of exploration missions beyond Mars, where solar panels can no longer provide sufficient energy and chemical propulsion would require a prohibitively high mass of propellant and/or prohibitively long trip times.
NTP is directly relevant to the Agency’s vision, mission, and long-term goal of expanding human presence into the solar system and to the surface of Mars because it provides the fastest trip time of all currently obtainable advanced propulsion systems.
Fast trip times will safeguard astronaut health by reducing exposure to zero gravity and cosmic radiation and reduce risks associated with reliability uncertainties inherent in complex systems as well as those associated with life-limited, mission critical systems.
Success factors for the NTP project
The overall goal of this Game Changing Development Program project is to determine the feasibility and affordability of a low enriched uranium (LEU)-based NTP engine with solid cost and schedule confidence. Eventually, the nuclear propulsion system would be integrated into a launch vehicle that would go to Mars. The project will be considered a success if these objectives are met.
- Demonstrate the ability to purify tungsten to 90 percent purity (or higher if possible) and determine the cost to produce a kilogram at that level of purity.
- Determine, to a conceptual level of fidelity, the technical and programmatic feasibility of an NTP engine in the thrust range of interest for a human Mars mission. The thrust range of interest will be agreed to by the Space Technology Mission Directorate and the project as soon as feasible after the start of the project.
- Determine the program cost of an LEU NTP system and the confidence level of each major cost element.
New nuclear fuel for deep space travel
Given its experience in developing and delivering nuclear fuels for the U.S. Navy, BWXT will aid in the design and testing of a promising, low-enriched uranium-based nuclear thermal engine concept and “Cermet” — ceramic metallic — fuel element technology.
During this three-year, $18.8-million contract, the company will manufacture and test prototype fuel elements and also help NASA properly address and resolve nuclear licensing and regulatory requirements.
A shift to low enriched uranium (LEU)—defined as a concentration of lower than 20 percent uranium-235—offers several potential advantages for a nuclear propulsion development program.
Security regulations for an LEU system could be less burdensome on the project budget and schedule. Handling regulations for an LEU source are similar to those for a university research reactor, opening up the development effort to partnerships with industry and academia.
Note: At the time of launch, there is almost no radiation released from the nuclear reactors. The nuclear-powered rockets are not used to lift off the Earth.
BWXT will aid NASA in refining the feasibility and affordability of developing a nuclear thermal propulsion engine, delivering the technical and programmatic data needed to determine how to implement this promising technology in years to come. (Schematic of test bed and images of test components – PDF file)
In late September 2017, the Nuclear Thermal Propulsion project will determine the feasibility of using low-enriched uranium fuel. The project then will spend a year testing and refining its ability to manufacture the necessary Cermet fuel elements. Testing of full-length fuel rods will be conducted using a unique NASA Marshall test facility.
Work on the program will begin immediately. Approximately 15 BWXT employees in Lynchburg, Va., will contribute to this effort.
Nuclear-powered rocket concepts are not new. The United States conducted studies and significant ground tests from 1955 to 1972 to determine the viability of such systems, but ceased testing when plans for a crewed Mars mission were deferred. Since then, nuclear thermal propulsion has been revisited several times in conceptual mission studies and technology feasibility projects.
Update on Russian nuclear rocket
According to a 2013 report by World Nuclear News, Russia is also working on a nuclear rocket that would generate electricity for a plasma thruster. The specific thrust of such a system could be 20 times that of current chemical rockets, cutting the time to travel to Mars to just over a month.
The Russian project to develop the nuclear thrust module began in 2010 with a budget of RUB17 billion ($532 million) and a plan to launch in 2018. The majority of this is allocated to Rosatom’s development of the reactor unit.
In 2016 Wired Magazine published a report that Roastom was working on a plasma thrust system that would get astronauts to Mars in 45 days. However, the Rosatom web page cited in the article is no longer online.
Searches of the Rosatom web site (in English), and on Google, did not turn up any new material from Rosatom on this R&D work. A state-owned media site RT published these photos of the Russian plasma technology about the same time as the Wired article.
A more detailed report, published by the Daily Mail UK also about the same time as the Wired Magazine piece, provided additional details on the Russian nuclear propulsion program. It included a number of significant images of components and complete rocket systems for a six week transit to Mars. It reported claims by Rosatom the the technology would be ready for a test of a nuclear propulsion system in 2018.
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Thanks to renewed interest in exploring the Red Planet in recent decades, NASA has begun new studies of nuclear thermal propulsion, recognizing its potential value for exploration of Mars and beyond.
The Nuclear Thermal Propulsion project is managed by NASA’s Game Changing Development Program, part of the agency’s Space Technology Mission Directorate.
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In your post you write: “Note: At the time of launch, there is almost no radiation released from the nuclear reactors.” I take it that means the LEU is fresh and un-irradiated at the time of launch, and that normal chemical rockets are used to lift-off into orbit. Can you point me to a link that describes this as a program requirement or goal? Is the first time the reactor ever goes critical when it is already in space? No need for ground testing prior to launch?
It is a well known safety protocol for RTGs that powered Cassini and other deep space missions that the reactor technology has to be able to survive a failed launch.
In the case of LEU the plan is not to allow start of the reactor to occur until the spacecraft is in orbit. This safety measure means that in the event of a failed launch, all you have is uniradiated fuel which is by its nature contact handled the same as any other nuclear fuel elements at 3-5% U235.
Please contact NASA and BWXT for further details.