Nicholas Dunn, of Ashburton Borough School, asks :-

Can nuclear power be used to drive a space ship?

Colin Keay, a space physicist at Newcastle University in Australia, responded.

In principle nuclear power may be harnessed in many ways to drive a spacecraft. Most are either impractical with current technology or highly undesirable for environmental reasons.

In the 1960's the Americans developed Project Orion but it was quashed, much too messy. The idea was to eject a succession of small nuclear bombs out the back to explode against a large shock absorber and push the vehicle to higher speeds. The bomb products would have blown all around the solar system, ruining surface studies of everything from the largest Jovian moons to small asteroids, comets and meteoroids.

However small nuclear power generators have been employed on a number of spacecraft and these are capable of driving modest thrusters using electrically charged atoms as propellant.

I consider that the best hope for nuclear power propulsion will come when fusion reactors are eventually perfected and adapted for really deep space operation. A huge scoop in front traps hydrogen which is channelled into the reactor, fused to form helium at a temperature of millions of degrees, and fired out the back to provide thrust. Hydrogen is the most prevalent element in the solar system as well as interstellar space and the production of more helium will do no harm.

With luck, Nicholas, you may live long enough to be around when the first hydrogen-fusion spaceprobe accelerates itself away to places unknown!