The US is planning to test a spacecraft engine powered with nuclear fission, an advancement seen as key to long-haul missions including “ultra-fast” manned journeys to Mars, the top official at the space agency Nasa has said.

Nasa will partner with the US military’s Defense Advanced Research Projects Agency (Darpa) to develop the nuclear thermal propulsion engine and launch it into space, Nasa administrator Bill Nelson said on Tuesday (24 January).

Nasa will work with Darpa to develop and demonstrate the technology as soon as 2027.

Using current technology, Nasa says, the 300-milion-mile (482 million km) journey to Mars would take about seven months. Engineers do not yet know how much time could be shaved off using nuclear technology, but Nelson said it would allow spacecraft and humans to travel in deep space at record speed.