Science Seminars

5/2/2013 The Radiation Environment on Mars measured by RAD on MSL

Speaker: Don Hassler (SwRI)
Date: Thursday, May 02, 2013
Time: 4:00 PM
Location: SPSC W120

Seminar Abstract:

An important part of assessing present and past habitability of Mars is to understand and characterize “life limiting factors” on the surface, such as the radiation environment. Radiation exposure is also a major concern for future human missions and characterizing the radiation environment, both on the surface of Mars and inside the spacecraft during the cruise to Mars, provides critical information to aid in the planning for future human exploration of Mars. The Radiation Assessment Detector (RAD) was the first MSL instrument to start collecting data, beginning its science investigation during cruise (10 days after launch) and making the first ever measurements of the radiation environment on another planet. RAD is an energetic particle analyzer designed to characterize a broad spectrum of energetic particle radiation including galactic cosmic rays, solar energetic particles, and secondary neutrons created both in the Mars atmosphere and regolith. RAD observations consist of a time series of periodic (typically 30 minutes) measurements of charged particles from protons (Z=1) up to iron (Z=26) for energies above >10 MeV/nucleon, as well as  neutrons from 10 to ~ 100 MeV. These synoptic observations are designed to characterize both the short term variability associated with the onset of solar energetic particle events as well as the long term variability of galactic cosmic rays over the solar cycle.This talk will discuss the results obtained during the ~7 months of cruise observations, which included good characterization of the radiation dose inside the MSL spacecraft (not unlike that expected inside a future manned spacecraft in deep space), as well as the first-ever measurements of the radiation environment on the surface of Mars. With increased solar activity associated with the current solar maximum, direct measurements of the contribution from solar energetic particle events to the total effective dose on the surface of Mars, as well as the contribution from atmospheric and albedo neutrons, is increasingly important. RAD is supported by NASA (HEOMD) under JPL subcontract #1273039 to SwRI, and by DLR in Germany under contract with Christian-Albrechts-Universitat (CAU).