SA51D-03
Monitoring the Heliospheric Conditions at Mars Using MSL/RAD Measurements
Friday, 18 December 2015: 08:45
2016 (Moscone West)
Jingnan Guo1, R F Wimmer-Schweingruber1, Cary J Zeitlin2, Scot CR Rafkin3, Don Hassler3, Arik Posner4 and MSL/RAD science team, (1)University of Kiel, Kiel, Germany, (2)Southwest Research Institute, Durham, NH, United States, (3)Southwest Research Institute Boulder, Boulder, CO, United States, (4)NASA Headquarters, Washington, DC, United States
Abstract:
The Radiation Assessment Detector (RAD), on board Mars Science Laboratory's (MSL) rover Curiosity, measures the radiation dose rate as well as the energy spectra of energetic charged and neutral particles at the surface of Mars. With these first-ever measurements of GCR fluxes on the Martian surface, RAD can be used as a monitor for heliospheric modulation at Mars location, similar to neutron monitors at Earth. We do this by first correlating the GCR dose rate measurements at Mars and solar modulations at Earth when there is a good magnetic connection between the two planets. With the thus obtained correlation we obtain an empirical function for the dependence of the modulation parameter at Mars on RAD dose rate. This function can in turn help to calibrate the heliospheric modulation at Mars throughout the MSL/RAD mission period. The resulting solar modulation at Mars and at Earth over three years (>1000 sols) is then compared. In order to verify our 'prediction' method, we use the local modulation parameter at Mars as an input for Badhwar O'Neil model providing the primary spectra for PLANETOCOSMIC simulations which eventually model the surface particle spectra that can be compared with RAD measurements of the spectra.
