WASHINGTON Cosmic rays are so dangerous and so poorly understood that people are unlikely to get to Mars or even back to the moon until better ways are found to protect astronauts, experts said on Monday.
And NASA is not properly funding the right experiments to find out how, the National Research Council committee said.
"One of the big issues is they have really cut funding for biology issues," retired space shuttle astronaut James van Hoften, who chaired the committee, said in a telephone interview.
"It is tough on them when they don't have any new money coming in. They are using old data," he added -- including research done on survivors of the nuclear bombings of Japan during World War Two.
"Given today's knowledge and today's understanding of radiation protection, to put someone out in that type of environment would violate the current requirements that NASA has."
The committee of experts agreed that NASA'S existing radiation safety standards can protect astronauts and they urged the U.S. space agency to keep them in place.
The Earth's bulk, atmosphere and magnetic field protect life from the solar radiation and the cosmic rays that travel through space. Astronauts have just a thin layer of shielding.
Van Hoften knows from personal experience.
"My introduction to space radiation came first-hand as a crew member aboard the Space Shuttle Challenger in April 1984. 'What the heck was that?' I blurted out after seeing what looked like a white laser passing quickly through my eyes," van Hoften wrote in the introduction to the report.
"'Oh, that's just cosmic rays,' said Pinky Nelson, my spacewalking partner and space physicist. The thought of extremely high-energy particles originating from a distant cosmic event passing easily through the space shuttle and subsequently through my head made me think that this cannot be all that healthy. The truth of the matter is that it is not."
NOWHERE TO HIDE
The cosmic rays include galactic cosmic radiation or GCR and solar particles.
"You can put on very thick walls and they just won't protect you from that," van Hoften said. "The younger you are the worse it is," he added, because as with many types of radiation, it can take years for the damage to cause disease.
"It might be OK if you just send a bunch of old guys like me," he laughed.
Any mission to Mars using current technology would take three years, van Hoften said. That long in space would subject astronauts to too much radiation .
"It hasn't really gotten the airing that it needs. In the committee we stewed over this for a long time before we said anything," he added.
Ejections of dangerous particles from the sun can be forecast, but astronauts must hide in specially shielded areas of shuttles or space stations and may miss important tasks, the committee said.
Adding more shielding can make spacecraft too heavy and is too expensive, added the report from the council, one of the independent National Academies of Science that advises the federal government.
The report, commissioned by NASA's Exploration Systems Mission Directorate, said the radiation poses cancer and other health risks for years after astronauts return to Earth.
"The committee finds that lack of knowledge about the biological effects of and responses to space radiation is the single most important factor limiting prediction of radiation risk associated with human space exploration," the report reads.
(Reporting by Maggie Fox; Editing by Xavier Briand)