Space Weather

Cover image for Vol. 15 Issue 2

Impact Factor: 2.398

ISI Journal Citation Reports © Ranking: 2015: 26/62 (Astronomy & Astrophysics); 30/81 (Geochemistry & Geophysics); 30/84 (Meteorology & Atmospheric Sciences)

Online ISSN: 1542-7390

Associated Title(s): Space Weather Quarterly

Miniature detector measures deep space radiation

The 1972 journey of Apollo 17 marked not only the last time a human walked on the Moon but also the most recent manned venture beyond the outer reaches of the Earth's atmosphere. With preparations being made for humans to once again explore deep space, important steps are under way to quantify the hazards of leaving low-Earth orbit. One significant risk for long-distance missions is the increased exposure to ionizing radiation—energetic particles that can strip electrons off of otherwise neutral materials, affecting human health and the functioning of spacecraft equipment. The deep space probes that are being sent to measure the risks from ionizing radiation and other hazards can be costly, so maximizing the scientific value of each launch is important. With this goal in mind, Mazur et al. (2011) designed and developed a miniature dosimeter that was sent into lunar orbit aboard NASA's Lunar Reconnaissance Orbiter (LRO) in 2009. Weighing only 20 g, the detector is able to measure fluctuations in ionizing radiation as low as 1 mrad (equivalent to 1.0 × 10-8 J of energy deposited into 1 kg) while requiring minimal power and computer processing. The postage stamp–sized detector tracked radiation dosages for the first year of LRO's mission, with the results being confirmed by other onboard and near-Earth detectors. The authors found that ionizing radiation levels were 30% lower in lunar orbit than when the spacecraft was in transit, with a total dosage roughly 22 times the annual background rate on Earth. They suggest that their detector, with its small footprint and low power demand, could be a staple for future deep space missions.

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