Nasa eyes nuclear step for rocket science

Nasa wants to develop atomic-powered rockets and nuclear reactors for colonies on other planets.

The agency has proposed spending almost a billion dollars on the controversial project over the next five years.

Experts say the investment will revolutionise space travel and make conventional rockets a thing of the past.

Rockets are relatively slow and expensive because of the enormous amount of fuel they need to escape the Earth's gravity.

It is uneconomic to carry fuel into space to power craft once they are there, so current probes rely on the gravity of other planets - adding years to a journey.

However nuclear power, which could fire a craft to faster and faster speeds and then slow it down before its arrival, might halve the 17-year journey time to Pluto.

The plan will face opposition from groups who fear a launch accident could scatter radioactive material around the globe.

But Ed Weiler, Nasa's associate administrator for science, said: "The number one issue would be safety."

He told engineers: "Anything that we build would have to safely survive the worst possible scenario, which would be a rocket blowing up on the pad. If you can't show that a system could survive that, then don't talk to me."