Near‐Real‐Time Situational Awareness of Space Radiation Hazards

Abstract

.Galactic cosmic rays and solar energetic particles (SEPs) present formidable radiation hazards [e.g., Cucinotta et al., 2010] for human and robotic operations beyond low Earth orbit (LEO). As new plans are conceived for human exploration beyond LEO, these space radiation hazards create critical needs for accurate situational awareness. A new near-realtime tool called PREDICCS (Predictions of Radiation From REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and Other SEP Measurements, http://prediccs. sr.unh.edu) provides the first online system for predicting and forecasting the radiation environment in near-Earth, lunar, and Martian space environments.PREDICCS integrates a host of near-real-time measurements being made by satellites currently in space with numerical models (e.g., EMMREM ) to determine radiation doses and dose equivalents that characterize biological impacts and energetic particle propagation codes that can accurately project radiation levels through the inner solar system and out to Mars. PREDICCS provides updates of the radiation environment on an hourly basis and archives the data weekly, monthly, and yearly to provide a clear historical record of the space radiation environment.The PREDICCS tool provides in-depth data to characterize how hazardous SEP events are throughout the solar cycle, provides detailed information on how often large events that have significant risk associated with them are likely to be observed, and facilitates comparison of the near-Earth and lunar radiation environments to that near Mars. As an example, Table 1 shows the lens doses (in centigrays; 1 centigray = 1 rad) and dose equivalents (in centisieverts; 1 centisievert = 1 rem) for full-sphere radiation exposure from PREDICCS over the last 12 months. The PREDICCS lens dose quantifies the energy per mass deposited in 1 gram per square centimeter of water, which is a proxy for the biological impact to the human eye. Large SEP events on 23 January 2012, on 27 March 2012, and in the summer of 2012 contributed significantly to the hazards of the space environment over this interval. We observe that the dose rate limit of 200 centigrays for the lens dose [Cucinotta et al., 2010] is exceeded for nominal spacecraft shielding.Among the satellite measurements used by PREDICCS are data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on NASA's Lunar Reconnaissance Orbiter [Spence et al., 2010]. For the SEP events of 23 January (Figure 1 Figure 1. A direct comparison of the results of PREDICCS at the Moon (red and green) and at Mars (purple) with measurements of CRaTER (blue) strongly validates PREDICCS. Shown here are PREDICCS proxies for the lens dose rate at the Moon behind 0.3 grams per square centimeter of aluminum shielding (red line) and behind 1 gram per square centimeter of aluminum shielding (green dashed line), the CRa-TER measurement for the lens dose rate (blue dots) behind 0.22 grams per square centimeter of aluminum shielding, and the PREDICCs lens dose rate proxy at Ma...

Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep space exploration?

“…(Note that SEP events are often characterized as solar proton events, SPEs, which emphasize observed elevated proton fluences.) We study the probability of SEP events using a near‐real‐time tool called PREDICCS (Predictions of Radiation from REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and other SEP measurements, http://prediccs.sr.unh.edu [ Schwadron , ]), an online system for nowcasting the radiation environment in near‐Earth, lunar, and Martian space environments. The PREDICCS tool has been shown to be very accurate for dose rate calculations [ Joyce et al , ] in comparison to CRaTER observations.…”

“…Probability (%) versus integrated BFO dose for 30 day to 1 year missions. We use the PREDICCS database [ Schwadron , ] ( http://prediccs.sr.unh.edu) to build up statistics for the probability of SEP events of varying integrated dose behind spacecraft shielding (10 g/cm 2 ). The database currently provides doses for the period from July 2011 through April 2014.…”

Solar Energetic Particles and Space Weather: Science and Applications

“…Earth-Moon-Mars Radiation Environment Module (EMMREM) (Schwadron 2010), Predictions of radiation from REleASE, EMMREM and Data Incorporating CRaTER, COSTEP and other SEP measurements (PREDICCS) (Schwadron 2012), Solar Energetic Particle MODel (SEPMOD) (Luhmann et al 2010), SOLar Particle ENgineering Code (SOLPENCO) (Aran et al 2006), and SOLPENCO2 (provides SEP modelling away from 1 AU to the SEP statistical model of the SEPEM project (Crosby et al 2015))) (b) Empirical models (e.g. University of Malaga Solar Energetic Particle (UMASEP) system (Núñez 2011), Relativistic Electron Alert System for Exploration (REleASE) (Posner 2007), Proton Prediction System (PPS) , PROTONS system (Balch 2008), GLE Alert Plus (Kuwabara et al 2006;Souvatzoglou et al 2014) and Laurenza's approach (Laurenza et al 2009)) In some cases forecasting systems rely on methods from both categories such as the SEPForecast tool built under the EU FP7 COMESEP project (263252) (Crosby et al 2012), (http://www.comesep.eu/alert/).…”

Space Weather Quarterly Volume 12, Issue 1, 2015

“…(Note that SEP events are often characterized as solar proton events, SPEs, which emphasize observed elevated proton fluences.) We study the probability of SEP events using a near-real-time tool called PREDICCS (Predictions of Radiation from REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and other SEP measurements, http://prediccs.sr.unh.edu [Schwadron, 2012]), an online system for nowcasting the radiation environment in near-Earth, lunar, and Martian space environments. The PREDICCS tool has been shown to be very accurate for dose rate calculations in comparison to CRaTER observations.…”

“…As a practical exercise, we compute the length of time within acceptable risk that an astronaut could be exposed to the level of GCR radiation shown in Figure 1 We use the PREDICCS database [Schwadron, 2012] (http:// prediccs.sr.unh.edu) to build up statistics for the probability of SEP events of varying integrated dose behind spacecraft shielding (10 g/cm 2 ). The database currently provides doses for the period from July 2011 through April 2014.…”