The Phantom Torso: Testing the Effects of Radiation on Space Travelers By Leonard David Senior Space Writer posted: 07:00 am ET 04 December 2000 ET
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WASHINGTON -- International Space Station crew members will be joined by a spooky-looking visitor next year.
You could say its the anatomy of a science experiment. NASA scientists call it the Phantom Torso.
This part-dummy, part-dosimeter-imbedded torso is a mock-up of a humans upper body, minus a set of arms.
The sensor-laden Phantom Torso is built to determine the effects of
radiation on the human body. Dosimeters are mounted at spots where critical organs are located: the head, the heart, the liver and kidneys, for example.
Blasts of radiation
Spacecraft, such as the space shuttle and the station, can be bombarded by various energetic particles.
For one, solar storms churn out energy that can pose health risks. These radiation fields can result in doses to astronauts that are hundreds of times greater than those experienced on Earth.
The Phantom Torso, which will fly aboard the space shuttle next April, is built to determine the effects of radiation on the human body.
High radiation levels are nasty to space travelers. They may kill cells. Tissue can be damaged or mutations caused that lead to cancer, cataracts, central nervous system injury or other diseases, particularly certain types of leukemia.
Off-the-shelf
Flying next April on board a
space shuttle, the Phantom Torso will find a new home in space. Once off-loaded from the shuttle by astronauts, the cadaver-like castaway is to be left in Node 2, the attachment point for the U.S. laboratory, Destiny.
"It will be there for roughly four months," said Gautam Badhwar, chief scientist for space radiation at NASAs Johnson Space Center in Houston, Texas. "Its what we call a fully-instrumented complete torso. It does not have the arms and the stuff below your knees, basically," he said.
The torso comes replete with the full bone structure inside. Its sort of an off-the-shelf torso, Badhwar told SPACE.com, in that its nearly identical to those used to train radiologists in hospitals.
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The flight next year, wont be the torsos first space jaunt. It was aboard STS-91, a shuttle trip in June 1998 that lasted nearly 10 days.
Dose depths
The Phantom Torso is divided into 34 1-inch (2.3 centimeter) slices, Badhwar said. At roughly 1,600 locations, passive detectors are mounted internal to the framework. They measure radiation dose depths from front to back, side to side, etc., he said.
What is Radiation Sickness
Radiation sickness is an effect that radiation has on body tissues. Radiation effects can result in acute, delayed, or chronic illnesses. Depending onthe dose and type of radiation, symptoms can be mild, transitory, or severe. A person can suffer from loss of appetite, vomiting, and diarrhea to brain damage and death. Even small doses of radiation are a worry, due to the possibility oflong-term genetic effects and increased cancer rates.
At five critical organ-tissue locations within the torso, another set of tiny active devices can record what is happening to the torso as a function of time.
Other instruments mounted on the outside of the space station will sense galactic cosmic radiation and
radiation from solar storms, as well as trapped particles in the South Atlantic Anomaly -- an area where the Earths radiation belts dip closest to our planet.
"The two instruments mounted outside will tell us about the spectrum of particles that first hits space station shielding. As they go through the station, the radiation gets modified. So we will measure the radiation before it hits the Phantom Torso," Badhwar said.
The modified radiation field has a significantly different effect on tissue than the primary radiation, Badhwar said.
Blood-forming organs
The health risk from radiation exposure of astronauts is a major issue of long-term space flights, Badhwar said.
The Phantom Torso is expected to yield a more accurate portrait of human radiation dosage.
Also, information gleaned from the torso experiment can help determine the best types of materials and methods for shielding space crews.
Information is needed, in particular, about the radiation impact on blood-forming organs, said Peter Ahlf, flight program lead for life sciences within the space agencys Biological and Physical Research Enterprise at NASA Headquarters.
"For shuttle flights, this is not as critical because of the short durations," Badhwar said. "But with long-duration flights, if you make a 20-percent error it starts to decrease the amount of time that the crew can either spend in space, or how frequently they can be rotated back to the station," he said.
Below the belts
Today, space crews are flying below the radiation belts that encircle Earth.
In the future, as space explorers return to the Moon, are stationed at locales between the Earth and Sun, or sent Mars-ward, they face even greater risks.
"You definitely will need some kind of storm shelter," Badhwar said. Inside such a shelter, crews would be protected against life-threatening blasts of radiation. Work is now ongoing to study radiation-thwarting materials, he said.
Radiation hazards in high-altitude space can be a showstopper.
That fact was pointed out in a recent National Academy of Sciences study on radiation and the International Space Station.
The report details the great solar storm of August 4, 1972. That event, like William Tells apple-splitting arrow, split the eight months between the last two
The storm delivered a total dose of radiation over half a day that, had it missed the middle and hit the Apollo mission at either end, would have caused the two crew members who had ferried down to the Moon's surface in the lunar module to have suffered acute radiation sickness and, perhaps, could have even killed them.
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