New measurements of total ionizing dose in the lunar environment

Abstract

We report new measurements of solar minimum ionizing radiation dose at the Moon onboard the Lunar Reconnaissance Orbiter (LRO) from June 2009 through May 2010. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on LRO houses a compact and highly precise microdosimeter whose design allows measurements of dose rates below 1 micro‐Rad per second in silicon achieved with minimal resources (20 g, ∼250 milliwatts, and ∼3 bits/second). We envision the use of such a small yet accurate dosimeter in many future spaceflight applications where volume, mass, and power are highly constrained. As this was the first operation of the microdosimeter in a space environment, the goal of this study is to verify its response by using simultaneous measurements of the galactic cosmic ray ionizing environment at LRO, at L1, and with other concurrent dosimeter measurements and model predictions. The microdosimeter measured the same short timescale modulations in the galactic cosmic rays as the other independent measurements, thus verifying its response to a known source of minimum‐ionizing particles. The total dose for the LRO mission over the first 333 days was only 12.2 Rads behind ∼130 mils of aluminum because of the delayed rise of solar activity in solar cycle 24 and the corresponding lack of intense solar energetic particle events. The dose rate in a 50 km lunar orbit was about 30 percent lower than the interplanetary rate, as one would expect from lunar obstruction of the visible sky.

Efficient Data-Processing Algorithms for Wireless-Sensor-Networks-Based Planetary Exploration

“…Figure 11 shows the total samples covered in one Moon synodic cycle with a sampling period of 5 mins, where the TID measurement range is designed to cover TID from 25 to 50000 Rad. It must be noted that the TID rate used in this paper ( Figure 11) changes much faster than the actual measured one, obtained from the Lunar Reconnaissance Orbiter [34]. However, the TID processing results are still valid, as the rate in Figure 11 is qualitatively the same as the one reported in [34] and, in addition, it is better suited to the measurement range of the SWIPE TID sensor.…”

Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond

“…Data were obtained from a combination of empirical measurements and modeling. Direct measurements are from the EXPOSE-E & EXPOSE-R radiometerdosimeter on the exterior of the ISS (Dachev et al 2015(Dachev et al , 2012, the Radiation Assessment Detector on the Mars Science Lander (Zeitlin et al 2013), the Lunar Reconnaissance Orbiter (Mazur et al 2011), and the Advanced Composition Explorer probe located at lunar Lagrange point L1 (Stone et al 1998). Model results are from CREME 96 for GCRs (Tylka et al 1997), ESP-PSYCHIC for SEPs (Xapsos et al 2007(Xapsos et al , 1998, AE9/AP9 for trapped radiation in Earth orbit (Ginet et al 2013), and SHIELDOSE-2Q for dose vs. shielding thickness (Seltzer 1994;Truscott 2010).…”

The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission

“…For RPS, we telemeter the low and medium ranges that have 13.6 microRad and 895 milliRad resolution, respectively. We tested all four RPS dosimeters using a cobalt-60 gamma irradiator to confirm their dose equivalent gains, and have tested the design with 50 MeV protons (Mazur et al 2011). The dosimeters accumulate the dose as long as RPS is powered on, requiring ground-based processing in the RPS Science Operations Center to accurately derive the dose rate and account for power-off intervals for the calculation of total mission dose.…”

“…These dosimeters are the second generation of the design first flown on board the Lunar Reconnaissance Orbiter (Mazur et al 2011). For RPS, we telemeter the low and medium ranges that have 13.6 microRad and 895 milliRad resolution, respectively.…”