London, Oct 15 : An Indian origin researcher at NASA has said that a spacecraft shaped like a grapefruit spiked with cherries on sticks, is the best suited for long space voyages.

Ram Tripathi, a spaceflight engineer at the agency’s Langley Research Center in Hampton, Virginia, US, has said that the bizarre design might be the only way to protect the crew from cancers triggered by the searing radiation environments they would experience on long space trips.

The major radiation sources are galactic cosmic rays, charged particles that comprise anything from electrons up to the heavy metal elements and 'solar particle events', which fling out protons and helium nuclei.

The electrons, protons and heavy-metal ions such as iron and uranium whiz through the void and can all cause cancers.

But aluminium shielding capable of staving the radiation off on extended journeys would be prohibitively heavy, burning too much fuel.

“Exposure from the hazards of severe space radiation in long-duration deep space missions is 'the show stopper'. Protection from the hazards of severe space radiation is of paramount importance to NASA's new vision to reach the Moon, Mars and beyond,” Tripathi and his colleagues John Wilson and Robert Youngquist write in their paper in the journal Advances in Space Research.

The scientists suggest that positively and negatively charged metal spheres can be arranged on struts jutting out of the crew capsule, in carefully controlled directions, to give the crew a high degree of electrostatic radiation cover.

According to his calculations, the “cherries” would need to be between 10 and 20 metres in diameter and would be stationed about 50 metres from the crew capsule – the “grapefruit”.

These spheres would protect the crew by deflecting charged particles away from the central habitat.

“Spheres give you more volume and less mass, and most importantly, they evenly distribute the deflecting charges over their surface,” Tripathi said.

He said while the charged spheres would be made of lightweight hollow aluminium, the material shielding the crew capsule would incorporate the latterday wunderkind of chemistry – the carbon nanotube – in a novel composite with aluminium.

“The nanotubes are light, yet their toughness means they can take a pounding from heavy incoming ions. The take-home message from my research is that if we want to be 100% confident that we can protect the astronauts and their habitat, we are going to need a smart combination of material and electrostatic shielding,” New Scientist magazine quoted Tripathi, as saying. (ANI)