Going boldly where no monkey has gone before Photo: PAUL GROVER

It will be Nasa’s first experiment on primates in decades.

If a manned mission to Mars ever takes place, the human pilots will be outside Earth’s protective magnetic field for several months, unprotected from solar radiation. Little research has been done on this sort of long-term exposure to low doses of radiation.

Eleanor Blakely, a biophysicist at Lawrence Berkeley National Laboratory, said: "Obviously, the closer we get to man, the better."

The researchers are to pay particular attention to the effects on the monkeys’ central nervous systems and behaviour. The monkeys, previously trained to perform a variety of tasks, will be tested to see how the exposure affects their performance.

Jack Bergman, a behavioral pharmacologist at Harvard Medical School's McLean Hospital in Boston, said: "We realized there was a need for this kind of work.

"There's a long-standing commitment on the part of NASA to deep space travel and with that commitment comes a need for knowing what kinds of adverse effects deep space travel might have, what are the risks to astronauts. That's not been well assessed.

"The beauty of this is that we can assess at different time points after exposure, so not only do we get a sense of rather immediate effects, but then we can look again at longer time points.

"That kind of information just hasn't been available."

After the radiation exposure, the monkeys can look forward to a lifetime of being looked after by staff and veterinarians at McLean Hospital.

Nasa said in a statement: "McLean Hospital is responsible for the lifetime care of the primates. No further research is planned for them at this time."

The space agency has previously used 17 primates, mainly chimpanzees, to test the effects of launch G-forces and microgravity on humans, among other things.