The Canadian Space Agency (CSA), in cooperation with the International Space Station (ISS) international partners, is involved in the study of space radiation. The main goal of the CSA Operational Space Medicine Program is to develop technology and methods to measure and monitor astronauts' exposure to space radiation to better protect them from its harmful effects.
Radiation in space is much stronger than radiation experienced on Earth. For example, a typical daily radiation dose aboard the ISS is approximately equivalent to that received on Earth from natural sources (other than radon) in an entire year. This is because on Earth, humans are protected from most space radiation by our planet's atmosphere and magnetic field. With astronauts living on the ISS for longer periods of time, and the possibility of interplanetary space missions, it is necessary to continue improving technology to monitor and measure radiation, and to protect against it.
Radiation detectors or dosimeters are used to measure the radiation levels that astronauts are exposed to in space. Radiation dosimetry is the science of measuring the amount of radiation energy absorbed in a given area. The CSA works with NASA's Space Radiation Analysis Group (SRAG) to ensure that the astronauts' radiation exposures do not exceed the acceptable limits during a mission. The SRAG estimates how much radiation will be present during a mission based on solar activity forecasts provided by the National Oceanic and Atmospheric Administration (NOAA). They also monitor the actual radiation exposures during a mission based on data from personal dosimeters (radiation detectors worn by the astronauts) and area dosimeters (radiation detectors placed in different locations inside and outside a spacecraft). Along with the SRAG measurements, each astronaut's blood is collected to measure changes or mutations in the DNA (genetic material found within our cells) to determine his or her level of exposure and the extent of the damaging effects caused by radiation.
The CSA Operational Space Medicine (OSM) Group is supporting the development of two Canadian radiation dosimeters that can be used as personal or area dosimeters in the future aboard the ISS: Bubble Detectors and MOSFET Dosimeters. Bubble detectors are test-tube sized dosimeters that measure the neutron radiation dose to which astronauts are exposed. MOSFET dosimeters are miniature electronic devices that measure protons and electrons in real-time and can provide radiation dose readings for selected parts of the human body. Currently, the OSM Group is collaborating with the State Scientific Center of the Russian Federation Institute of Biomedical Problems (IBMP) of the Russian Academy of Sciences to use the Bubble Detectors and the MOSFET Dosimeters in the experiment called Matroshka-R scheduled for 2005-2008 on the Russian segment of the ISS.
The Matroshka-R experiment will investigate how much radiation different organs in the human body receive in space over prolonged periods of time. It uses a 'phantom', which is an imitation of a human body made of material equivalent to human tissue. Different depths of the phantom simulate locations of vital organs in the human body. Numerous radiation detectors, including Bubble Detectors and MOSFET Dosimeters, will be placed at various locations inside the phantom to determine how much radiation each organ receives.
The data gained from Matroshka-R will be vital to estimate health risks to astronauts aboard the ISS and on longer space missions since the total radiation risk depends largely on the dose received by the internal organs. It will also increase understanding of the distribution of different types of radiation within the ISS and within the human body.
Radiation technology and procedures developed for space are also used on Earth to help care for people exposed to high levels of radiation, such as chemotherapy patients.