Miniature detector measures deep space radiation

Abstract

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. designed and developed a miniature dosimeter that was sent into lunar orbit aboard NASA's Lunar Reconnaissance Orbiter (LRO) in 2009. Weighing only 20 grams, the detector is able to measure fluctuations in ionizing radiation as low as 1 microrad (equivalent to 1.0 × 10‐8 joules of energy deposited into 1 kilogram) 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. (Space Weather, doi:10.1029/2010SW000641, 2011)