Propulsion thermique nucléaire

US military wants nuclear-powered rockets for missions in cis-lunar space

For the US military, conventional rockets powered by chemical engines are not enough. On May 4, the DARPA or Defense Advanced Research Projects Agency announced that it was calling for proposals for the second and third phases of its nuclear-powered rocket project. This project concerns the design, development and assembly of a nuclear thermal engine for a first demonstration flight by 2026.

According to DARPA officials, these propulsion capabilities will allow the United States to strengthen its interests in space and expand the possibilities for NASA’s long-duration manned missions. The proposals received will serve as support for the DRACO program or Demonstration Rocket for Agile Cislunar Operations of DARPA. This program aims to develop a nuclear thermal propulsion system (NTP) that will be used in the space between the Earth and the Moon.

Nuclear thermal propulsion
DARPA Credits

According to reports, DRACO is part of the US military’s efforts to track cis-lunar space. Indeed, government and commercial activities will dramatically increase in this area over the next decade.

Characteristics of nuclear propulsion systems

NTP systems use fission reactors to operate. These reactors will heat the fuel, which may be hydrogen, to very high temperatures. The gas will then be ejected to create thrust.

NTP systems are significantly more powerful than electric propulsion systems. NTPs have a thrust-to-weight ratio 10,000 times greater. If compared to conventional chemical rockets, the propulsion efficiency is about 2 to 5 times higher.

NASA’s position

With the level of thrust that can be obtained from NTP systems, it is obvious that NASA is also interested in this type of system. The latter could possibly halve the duration of the journey to reach the planet Mars, which is currently 6 to 9 months. NASA’s fiscal year 2023 budget request is known to include $15 million to support nuclear propulsion research. However, for the moment, this budget request has not yet been approved by Congress.

For fiscal year 2022, the House of Representatives had allocated $110 million for nuclear thermal propulsion research. The House had rejected the Biden Administration’s proposal to focus NASA’s efforts on developing a nuclear reactor that could power manned bases on the Moon and Mars.

Either way, the year 2026 may be the year of the first flight of America’s first nuclear-powered rocket.


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