Washington, Oct 22 (IANS): Cosmic rays have created radiation hazards in space that potentially threaten future deep-space astronaut missions, said researchers.

Due to a highly abnormal solar activity, the solar wind is exhibiting extremely low densities and magnetic field strengths, which causes dangerous levels of hazardous radiation to pervade the space environment.

"The behaviour of the Sun has recently changed and is now in a state not observed for almost 100 years," said associate professor Nathan Schwadron of the Institute for the Study of Earth, Oceans and Space (EOS) at the University of New Hampshire in the US.

These conditions brought about the highest intensities of galactic cosmic rays seen since the beginning of the space age.

"While these conditions are not necessarily a showstopper for long-duration missions to the moon, an asteroid, or even Mars, galactic cosmic ray radiation in particular remains a significant and worsening factor that limits mission durations," Schwadron added.

The high radiation levels seen during the Sun's last minimum cycle limits the allowable days for astronauts behind spacecraft shielding.

Given the trend of reducing solar output, the allowable days in space for astronauts is dropping and estimated to be 20 percent lower in the coming solar minimum cycle as compared with the last minimum cycle.

"These data are a fundamental reference for the radiation hazards in near Earth 'geospace' and other regions of our Sun's vast heliosphere," Schwadron concluded.

The paper was published in the journal Space Weather.