Space scientist Ruth Bamford has no regrets about her suggestion that British researchers should build a Star Trek-style deflector shield to protect astronauts from radiation.

But she was unprepared for the deluge of e-mails from Trekkies, as Star Trek fans are called, following her presentation at the National Astronomy Meeting.

She said: "I used a picture of the Voyager, and then talked about the Starship Enterprise. As you can imagine, Star Trek fans contact you about every detail. I'm sorry, but it's only a story, it's not true."

The Trekkies' confusion between fact and fiction was understandable, in view of the startling nature of her talk.

She showed how close the early astronauts on Apollo missions in the 1960s and 1970s came to life-threatening illness, or sudden death from cosmic radiation caused by sudden eruptions of the sun.

They were only in space for about ten days at a time, and narrowly missed the solar flares.

She said: "We have the technology to send people to Mars. We could put people in space and probes on Mars - except for the radiation protection of the astronauts. It's a show-stopper.

"It's no longer acceptable. The gung-ho attitute of the Apollo missions is totally unacceptable today."

She added: "Both NASA and the European Space Agency have said: We are going to the moon and then on to Mars', but this problem has not been discussed much yet."

Dr Bamford, of the Rutherford Appleton Laboratory, near Harwell, and her colleague, Professor Bob Bingham, are uniquely placed to lead the development of a radiation shield.

Before joining RAL's space science department, they both worked at Culham on nuclear fusion, harnessing the reaction which gives the sun its heat with the aim of creating a virtually limitless source of energy for future power stations.

It works on the principle that energy can be released by forcing together atomic nuclei, rather than by splitting them, as in the case of the fission reactions that drive existing nuclear power stations.

At the Jet experiment, magnetic fields were used to keep energised gas called plasma away from the reactor wall. A nuclear fusion power station is still many years away from reality, but in the meantime the science has sparked some useful spin-offs.

Dr Bamford said: "The earth is protected by its own magnetic field - if it wasn't there, there would not be life - but Mars doesn't have a magnetosphere. From my experience in fusion, I know that we could make one very well.

"The technology to hold energetic particles away from a wall has been developed for fusion. Why not use the same technology to keep the plasma out?"

Crew members on the International Space Station retreat to a thick-walled room during solar flare-ups.

Exposure But these protective shelters are heavy and would not be practical on long-space journeys, since low-level but long-term exposure to radioactive particles is thought to be as harmful to health as sudden solar storms.

Dr Bamford and her colleagues have already created a small-scale experimental magnetic shield, and would eventually like to fly a test satellite to try the technology in space.

Now the RAL team - and other scientists - are applying for grants to build a larger prototype. Dr Bamford said Oxfordshire had a unique combination of skills for the project.

"I think we have the ability to do this better than anyone. We not only have space science here, we have Culham, which is the largest fusion laboratory in the world, and the Radiation Protection Division of the Health Protection Agency here on the Harwell site, whose staff understand about dose levels.

"They are in neighbouring laboratories and we all know each other. There is also Oxford Instruments - I would envisage that we would need a superconducting magnet."

She is unrepentant about her mention of Star Trek, and says that scientists enjoy science fiction, as long as it is based on science, and then extrapolated with imagination.

"I think it's a misconception that scientists lack imagination, but it has to be based on what is possible and scientifically credible."

And as for the deflector shield of the Starship Enterprise, she said: "That's exactly what a magnetic shield does. It's not surprising, because the scriptwriters had advice from NASA. It's not fantasy - it's within the bounds of possibility."

* Contact: Dr Ruth Bamford, 01235 446517, r.bamford@rl.ac.uk