New Delhi:
US space agency NASA has said that the surface in frigid and permanently shadowed region near the poles of the moon could get charged up because of the powerful solar storms.
The solar storms could be responsible for triggering sparks that may have resulted in vaporising and melting the soil on the moon, a new NASA study has revealed.
This finding may turn out to be evident when future samples from these regions will be analysed. This could then hold the key to understand the history of the solar system and the Moon.
Because Moon doesn't have an atmosphere, its surface is exposed to harsh environment of the space.
The impacts coming from small meteoroids constantly garden the top layer of the dust and the rock on the Moon, which is known as regolith.
"About 10 per cent of this gardened layer has been melted or vaporised by meteoroid impacts," said Andrew Jordan of the University of New Hampshire in the US.
"We found that in the Moon's permanently shadowed regions, sparks from solar storms could melt or vaporise a similar percentage," said Jordan.
Highly energetic, electrically charged particles are blasted into space by the explosive solar activity, like flares and coronal mass ejections.
We human being living on the Earth are protected by our planet's atmosphere that works as a shield against most of this radiation. Such is not the case with the Moon as it has no atmosphere and hence the particles such as ions and electrons slam directly into its surface.
They exist in two layers under the surface. The ions that are bulky fail to penetrate deeply as they are more likely to hit atoms in the regolith.
Hence, they form a layer closer to the surface while the tiny electrons slip through and form a deeper layer.
While the ions carry positive charge, the electrons have negative charge. Because opposite charges attract, these charges normally flow towards each other and balance out.
Researchers in 2014, however, found that strong solar storms would cause the regolith in the permanently shadowed regions (PSRs) of the Moon in order to accumulate charge in these two layers until explosively released, like a miniature lightning strike.
Because of the frigidity of the PSRs, the regolith becomes an extremely poor conductor of electricity. Therefore, during intense solar storms, the regolith is expected to dissipate the build-up of charge too slowly to avoid the destructive effects of a sudden electric discharge, called dielectric breakdown.
The research estimates the extent that this process can alter the regolith.
"This process is not completely new to space science - electrostatic discharges can occur in any poorly conducting (dielectric) material exposed to intense space radiation and is actually the leading cause of spacecraft anomalies," said Timothy Stubbs of NASA's Goddard Space Flight Center in Greenbelt in the US.
The team's analysis was based on this experience. From spacecraft studies and analysis of samples from NASA's Apollo lunar missions, the researchers knew how often large solar storms occur.The research was published in the journal Icarus.
(With inputs from PTI)
