The Aerospace Corporation Reports First Measurements of A Revolutionary Miniature Dosimeter

The tiny sensor offers an innovative option for measuring radiation dose and other space weather impacts on satellites.

EL SEGUNDO, Calif. (Sept. 15, 2011) -- A microdosimeter, designed and developed by a team of scientists and engineers from The Aerospace Corporation to monitor and accurately measure ionizing radiation in space, is a newly proven concept for small space weather sensors. A recent publication demonstrates the first results from a microdosimeter in orbit about the Moon on The Lunar Reconnaissance Orbiter (LRO). This relatively tiny sensor accurately measured the ionizing radiation environment while LRO was en-route to the moon and in low lunar orbit and is the first of its kind to monitor ionizing dose in space.

"A common obstacle to monitoring space environment hazards on satellites is the mass, power, and volume required for typical environment detectors. You quickly get into a competition for resources with the satellite payload and the bus, even when it's important to monitor things like radiation dose or single-event effects. This microdosimeter design essentially removes the competition for resources." said Dr. Joseph Mazur, the lead of the published study of the first-year's measurements from the microdosimeter on LRO.

The postage stamp-sized device weighs only 20 grams, requires only 280 milliwatts to operate, and outputs the accumulated dose as an analog voltage so that it looks like a standard thermistor for interfacing with spacecraft. The analysis based on the first year of the LRO mission showed that the microdosimeter measurements were within a few percent of those made by a much more capable science instrument on LRO that is 275 times heavier and consumes 24 times more power. The total ionizing dose at LRO was from high-energy galactic cosmic rays and the microdosimeter was shown to be sensitive enough to detect dose rates below 1 microRad(Si) per second. The authors also found that the dose rate was 30% lower in lunar orbit than when the spacecraft was in transit, with a total annual absorbed dose roughly 22 times the annual background rate on the Earth's surface.

"The LRO flight opportunity was valuable for our verification of the microdosimeter performance, because we housed it inside a very capable particle spectrometer to which we could compare our measurements," Mazur added. "We can now point our customers to the LRO results and say that we are ready to move ahead on incorporating these kinds of targeted space weather sensors on every space vehicle. The information they provide for such a small resource cost is a trade that can't be ignored."

Contact Pam Keeton, 703-812-0648 or Pamela.V.Keeton@aero.org.