Grapefruit-cherry looking spacecraft could head to Mars

William Atkins
Sunday, 21 October 2007 21:11

Science - Space

According to NASA engineer Ram Tripathi, the best way to protect astronauts from cosmic radiation on long-duration space trips could be a grapefruit-shaped spacecraft with a bunch of cherries stuck on sticks.           

Tripathis, along with John Wilson and Robert Youngguist, of Langley’s Research Center, write in the journal Advances in Space Research that radiation from galactic cosmic rays is a very dangerous part of any extended trips in space.

Galactic cosmic rays are charged, extremely high energy particles that enter the solar system. They consist of various particles from protons, helium nuclei (alpha particles), electrons, to heavy metal elements such as iron and uranium. Such particles cause cancer and are extremely dangerous to astronauts exposed to them on long missions in space, such as trips to Mars.

In fact, the researchers write: "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."

(New Scientist online (October 15, 2007) “Forget rockets – go to Mars in a cosmic fruit bowl”, http://space.newscientist.com/article/mg19626256.500-forget-rockets--go-to-mars-in-a-cosmic-fruit-bowl.html and New Scientist paper (October 13-19, 2007, page 27) “Balls on spikes to shield space crew”, [subscription required])

However, to counter this danger, Tripathi and his colleagues suggest that positively and negatively charged “cherry” hollow spheres—made with lightweight aluminum and about 33 to 66 feet (10 to 20 meters) in diameter—could be positioned on the ends of struts (sticks) about 164 feet (50 meters) from the surface of a “grapefruit” shaped capsule containing the astronauts.

The crewed capsule could be made of a protective composite of carbon nanotubes and aluminum. Nanotubes are extremely thin cylinders consisting of various carbon allotropes (carbon with different forms such as diamond, graphite) that are very strong and have novel electrical characteristics, which make them very useful with high-tech applications such as nanotechnology.

According to researchers (New Scientist magazine), "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."

The charged cherries would protect the human occupants by deflecting the dangerous cosmic particles that impinge on the capsule. The researchers contend that the spherical shape of the manned capsule helps to more consistently deflect the cosmic rays from the capsule’s surface (and the occupants inside), while minimizing the capsule’s weight (mass) and maximizing its volume (size).