19:00 16 April 03

NewScientist.com news service

The strange streaks of light seen by astronauts on space missions, linked to cosmic rays, still defy a full explanation.

The latest work confirms that the flashes can be correlated with the high-energy particles known as cosmic rays, which bombard the retinas of the astronauts' eyes. But it cannot completely explain how.

Understanding the nature of these enigmatic light shows is necessary to allow planners to fully assess the risks of future missions to astronauts, says research team leader Marco Casolino, of the Italian National Institute for Nuclear Physics. This would especially be the case for voyages beyond the Earth's magnetic field, which blocks most cosmic rays.

"This is a central nervous system effect that is not taken into account when calculating radiation doses," Casolino told New Scientist.