Nuclear powered space flights may be closer than they seem

Nasa) supposed to do if private companies like SpaceX get all the spacefaring glory? One option is to double down on investments in leading-edge advancements that may not pay off for years. Super-fast and manoeuvrable nuclear-powered rocket engines are one such technology. Last month, Nasa, partnering with the US Department of Defense, gave Lockheed Martin nearly $500 million to build and test one by 2027.

Without this collaboration, two things could be in jeopardy: Nasa’s dream of putting boots down in more parts of the solar system and the US’s upper hand in outer-space warfare. For nearly a century, rockets have operated in a fundamentally similar manner: A tank stores fuel that, when ignited, spits out a nozzle at high speed and creates thrust. The problem is, anything you might want to do with a spacecraft, such as manoeuvre towards Mars, requires lots of fuel, and because there are no gas stations in outer space (yet), a craft must carry as much fuel as its operators expect it will need for the duration of its mission.

Nearly half the mass of GOES-U, the 5.5-tonne weather satellite that Nasa plans to launch next year, will be fuel. Last year, Canada’s Telesat announced it would take a big financial hit due to insufficient fuel in a key communication satellite. Scientists have long recognized the need for more efficient alternatives.

In the 1950s, they came up with an explosive one: Use a small nuclear reactor to heat up a propellant, such as liquid hydrogen, to much higher temperatures than what can be achieved in a chemical rocket. Such an engine would be more than twice as efficient as a traditional rocket and much faster—in part because its engines can run non-stop for weeks, accelerating faster and faster. A