International Space Station Human Phantom Torso Space Radiation Exposures: The Matroshka Experiment

A Rando™ human phantom torso experiment is scheduled to fly on the International Space Station (ISS) mounted on and external to the Service Module in 2004 to simulate astronaut/cosmonaut extravehicular activity (EVA) space radiation exposures at various locations in the human body. The experiment will also contain the DLR/University of Kiel DOSTEL solid-state detector, the NASA Goddard Space Flight Center radiation effects experiment, and a NASA Johnson Space Center Tissue Equivalent Proportional Counter.

In this paper the Matroshka experiment and scientific objectives are discussed in detail with the primary focus on the anticipated human body organ exposures from the space radiation environment. Preflight space radiation exposure calculations are presented for a number of locations in and on the human phantom torso using models of the trapped particle and galactic cosmic radiation environments. A shielding model of the experiment container was developed and was combined geometrically with an existing shielding model of the ISS. A modified (arms and legs removed mathematically) Computerized Anatomical Male model was used to simulate the human body. High-energy particle transport and dose programs were utilized to compute the body organ exposures for several mission scenarios, which include orbital altitude and solar cycle conditions. Flight measurements taken by active and passive radiation detectors placed at the body organs of interest (eye, lung, kidney, stomach, intestine [colon], and several surface [skin] locations) will be compared with the pre-mission computations to validate the space radiation environment and shielding models. The organ exposures will provide insight to radiation risk assessments. The results will also be compared with a similar human phantom experiment, Phantom Torso Experiment, flown in the SpaceHab module on the Space Shuttle STS-91 mission in June 1998 near solar minimum and the ISS Human Research Facility experiment rack in 2001 near solar maximum.