A real dummy packed with bone and blood cells will endure
an intense radiation shower that simulates a solar flare — all in the name of
space exploration.
The plan involves using a high-energy proton beam to
strike a life-size
replica of a human torso embedded with hundreds of radiation sensors.
Future astronauts headed for
the moon or Mars won't have the protection of Earth's magnetic field
against solar radiation storms, and so scientists want to understand how much
the human body can endure.
The "Phantom torso" dummy consists of natural
bone, simulated skin and organs, and real human blood cells.
"We put blood cells in small tubes in the stomach
and in some places in the bone marrow," said Francis Cucinotta, chief
scientist for NASA's Radiation Program at the Johnson Space Center in Houston.
"One of the questions we have is whether the less shielded parts of the
bone marrow will be [much harder hit]."
The amount of radiation that reaches the bone marrow
could raise risks of leukemia and other cancers. Researchers can also watch the
real blood cells in the dummy so see how much the radiation damages DNA, and
whether the cells end up self-destructing or turning cancerous.
Astronauts have typically endured "chronic
exposure" to low-level radiation on past and current missions, when the
body has time to repair or replace damaged cells. But acute exposure to intense
radiation over a period of minutes or hours — such as during a solar flare
event — represents a more dangerous
dose.
"The biological effects are very sensitive to the
dose rate," Cucinotta explained. "A dose of radiation delivered over
a short amount of time is two to three times more damaging than the same dose
over a few days."
Apollo astronauts had a near-miss between the Apollo 16
and 17 missions to the moon, when an erupting sunspot unleashed a
record-setting barrage of solar radiation in 1972. Researchers plan to recreate
that event's effects at NASA's Space Radiation Lab at Brookhaven National
Laboratory in Upton, New York, by using a high-energy beam of protons on the European
Space Agency's Phantom Torso, named Matroshka.
Matroshka also has a NASA counterpart named Fred. Both
dummies have flown in
experiments aboard the space shuttle and the International
Space Station to show how chronic exposure to background radiation affects
the human body.
Whether chronic or acute exposure, the dummies can take
multiple blasts of space radiation. A quick transfusion of new red blood cells,
and then they're off on their next space adventure.
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