It may not be suitable for crash tests, but a dummy now rides on the outside of the International Space Station (ISS) It's mission: to give scientists a better idea of the radiation bombarding astronauts during spacewalks.
The dummy, a mock-human of natural bone, simulated organs and synthetic skin, was installated on the outside of the station's Russian Zvezda module during a spacewalk today by Expedition 8 crewmembers Michael Foale and Alexander Kaleri. Today's spacewalk is the first time the ISS will be left unattended during an EVA.
Rigged with numerous radiation detectors both inside and out, the dummy will spend a year on the space station's surface before being returned to Earth. The European Space Agency (ESA) experiment has named the dummy Matroshka since its layered nature is reminiscent of the famed matroishka Russian dolls. The German Aerospace Centre (DLR) is leading the Matroshka experiment for ESA.
NASA's Pete Hasbrook, increment manager for Expedition 8, said it was crucial Foale and Kaleri mounted the Matroshka experiment before the Sun reaches solar minimum, the point in the star's solar cycle when its activity reaches its lowest point. The sun is expected to reach its solar minimum phase in 2006.
Space phantom
At the heart of Matroshka is Phantom, an armless, legless torso of material designed to simulate the human body. While scientists have used Phantom-like dummies in the past aboard the space shuttle and inside the ISS, the radiation hazards of open space on sensitive body organs is still unclear.
The Phantom torso is sliced into into layers just under one inch (2.5 centimeters) thick, each containing dosimeters to detect the effects of radiation on human tissue-like material in "organs," including the eyes, lungs, colon, kidneys and stomach.
The space mannequin's "skin" is a coat of multi-layer insulation containing thermo-luminescence dosimeters, detectors that glow in proportion to the amount of radiation they receive. Those detectors are distributed about every inch (2.5 centimeters) throughout the torso to give scientists a depth-dose profile of radiation exposure.
A head-mounted charged-particle telescope, known as the Dosimetric Telescope (DOSTEL), will study effects of radiation not only from the Earth's Van Allen belts, but also the Sun and deep space.
Encapsulating the Phantom torso is a protective canister of carbon fiber-reinforced plastic. Itself replete with radiation sensors, the canister's interior supports an oxygen environment to better mirror its human space suit counterparts. Altogether the canister and Phantom weigh about 68 kilograms and stands 43 inches (110 centimeters) tall. It draws about 40 watts of power from the Zvezda module and will relay data to the ISS, as well as retain long-term radiation studies for later evaluation by scientists on the ground.
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