NASA is returning to the idea of sending people to Mars. It is collaborating with the Defense Advanced Research Projects Agency (DARPA) to test a nuclear rocket engine in space with the goal of using the technology for manned missions to the Red Planet. The agencies hope to demonstrate advanced nuclear heat engine technology as early as 2027, NASA Administrator Bill Nelson said:

“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.”

As part of the Demonstration for Rocket to Agile Cislunar Operations (DRACO) program, NASA’s Space Technology Administration will lead the technical development of the engine, which will be integrated with DARPA’s experimental spacecraft. NASA says a nuclear thermal rocket engine (NTR) could allow spacecraft to move faster, which could reduce the amount of supplies needed for long-duration missions. NTR engine can also make room for more science equipment and additional power for instruments and communications.

Back in the 1940s, scientists began to think about the possibility of using nuclear energy for space flights. In the USA, ground experiments started in this direction in the 50s. Budget cuts and changing priorities (such as focusing on the Space Shuttle program) led to NASA abandoning this project, never having completed a single test flight.

There are risks associated with NTR engines — such as the potential release of radioactive materials into the environment if a failure occurs in the atmosphere or in orbit. However, NASA says that the faster flight times that NTR engines can provide will reduce the risk to astronauts — they could cut the time it takes to get to Mars by a quarter. Nuclear rockets can be at least three times more efficient than conventional chemical propellants.

NASA is also considering using nuclear energy to power space exploration. In 2018, it conducted tests of a portable nuclear reactor as part of efforts to develop a system capable of providing energy to the habitat on Mars. Last year, NASA and the US Department of Energy selected three contractors to develop a fission surface power system that could be tested on the Moon. DARPA and the US Department of Defense have been working on other NTR engine projects for the past few years.