The Phantom Torso - Space Radiation

The most energetic are Galactic Cosmic Rays (GCRs) - the nuclei of atoms accelerated by supernova explosions outside our solar system. Cosmic ray nuclei can be as light as hydrogen, as heavy as iron, or almost anything in between. Because they lack their surrounding coat of negatively-charged electrons, GCRs are positively charged. The heavier nuclei carry the greatest charge, explains Badhwar. "As the charge increases, the amount of energy that the particle can deposit in tissue increases as well."

The other forms of particulate radiation consist mostly of protons. Most high-energy protons in the solar system come from the Sun. Although their charge is not great and they are less energetic than GCRs, solar protons can still be dangerous when they come in intense bursts known as solar flares.

The third kind of radiation, which surrounds Earth in areas known as Van Allen belts, consist mostly of decayed products from galactic cosmic ray interactions that have been trapped by Earth's magnetic field.

Some of this trapped radiation is confined to a region above the coast of Brazil, known as the South Atlantic Anomaly. "The Space Station goes through that Anomaly roughly five times a day," says Badhwar. The passage takes, at most, 22 or 23 minutes. That's good, he says.

"If you go through the trapped radiation belt in less than twenty minutes or so, then for the next seventy minutes the body has time to do some repair to the damage done by the radiation. The radiation from solar flares can actually do more harm, he says, simply because it comes at a rate that doesn't give the body time to recover.

n order to measure space radiation as it propagates through Fred's body, Badhwar and his team have sliced Fred horizontally into 35 one-inch layers. In each section they've made holes for radiation detectors called dosimeters. The torso carries 416 lithium-crystal based passive dosimeters, which simply record the total radiation dose received throughout the mission. Fred is also equipped with 5 active detectors. These, placed at the Phantom's brain, thyroid, heart, colon, and stomach, can track the times that the radiation exposures took place.