Nuclear rocket to trim Mars travel time from seven to four months

The benefits of a shorter voyage would include less exposure to cosmic radiation for the crew.

One of the last pictures returned from NASA]s Insight spacecraft on Mars: the red Martian dust has covered the craft, depriving its solar panels of the ability to supply energy.

NASA plans to build a nuclear-powered rocket to almost halve the time it takes to travel to Mars.

Passage to the red planet takes about seven months at present. Engineers believe that this could be cut to about four months using what is known as nuclear thermal propulsion.

The benefits of a shorter voyage would include less exposure to cosmic radiation for the crew. “If we have swifter trips for humans, they are safer trips,” Pam Melroy, the NASA deputy administrator and former astronaut, said.

NASA wants to send astronauts to Mars by the early 2040s, using a crewed mission to the moon as a stepping stone as soon as 2025.

The new, faster spacecraft would be equipped with a nuclear thermal engine, technology that has been on the agency’s radar for more than half a century. The aim is to test a prototype in space by the end of 2027.

A fission reactor – similar to those used in nuclear power stations, but much smaller – would generate very high temperatures, up to about 2700C. This would warm a liquid propellant, probably supercooled hydrogen.

The heat would convert the liquid propellant into a gas, which would expand and be directed through a nozzle to provide thrust. This process, according to NASA, is at least three times more efficient than the chemical propulsion used by rockets at present, which typically produce large amounts of thrust but only for short periods of time. A nuclear system would use up its gas propellant more slowly than a conventional rocket burns fuel. This should make it easier for astronauts to abort missions and turn back to Earth should something go wrong midway to Mars.

The nuclear propulsion would not be used for the initial blast-off; it would be switched on once the craft had left Earth. NASA has suggested that at first it would be used to ferry people and equipment to the lunar surface.

Harnessing nuclear thermal propulsion has long been a dream of the space agency. In the 1960s Wernher von Braun, the German-American engineer widely regarded as the father of NASA’s original lunar program, drew up plans to use such a system to send astronauts to Mars.

Bill Nelson, the NASA administrator, said: “With the help of this new technology, astronauts could journey to and from deep space faster than ever.”

NASA is teaming up with the Defence Advanced Research Projects Agency, a research arm of the US Defence Department. NASA will oversee the engineering of the nuclear rocket engine, which will go into an experimental spacecraft developed by DARPA. It will be part of a project known as Demonstration Rocket for Agile Cislunar Operations, or Draco.

The Times