SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 10 - MAY 19, 2006

93 SPACE RADIATION
Includes cosmic radiation; and inner and outer Earth radiation belts.

For biological effects of radiation on plants and animals see 51 Life Sciences; on human beings see 52 Aerospace Medicine

For theory see 73 Nuclear Physics.

20060013117 NASA Goddard Space Flight Center, Greenbelt, MD, USA

Europa Surface Radiation Environment for Lander Assessment

Cooper, John F.; Sturner, Steven J.; [2006]; 1 pp.; In English; Astrobiology Science Conference 2006, 26-30 Mr. 2006, Washington, DC, USA; No Copyright; Avail.: Other Sources; Abstract Only

The Jovian magnetospheric particle environment at Europa's surface is critical to assessment of landed astrobiological experiments in three respects: (1) the landing site must be chosen for the best prospects for detectable organic or inorganic signs of Life, e.g. regions of freshly emergent flows from the subsurface; (2) lander systems must reach the surface through the Jovian magnetospheric environment and operate long enough on the surface to return useful data; (3) lander instrumentation must be capable of detecting signs of life in the context of the local environmental radiation and associated chemistry. The Galileo, Voyager, and Pioneer missions have provided a wealth of data on energetic particle intensities throughout the Jovian magnetosphere including from many flybys of Europa. cumulative radiation dosages for spacecraft enroute to Europa can be well characterized, but knowledge of the surface radiation environment is very limited. Energetic electrons should primarily impact the trailing hemisphere with decreasing intensity towards the center of the leading hemisphere and are the most significant radiation component down to meter depths in the surface regolith due to secondary interactions. Observed surface distribution for sulfates is suggestive of electron irradiation but may have alternative interpretations. Having much-larger magnetic gyroradii than electrons, energetic protons and heavier ions irradiate more of the global surface. The particular orientations of electron, proton, and ion gyromotion would project into corresponding directional (e.g., east-west) anisotropies of particle flu into the surface. Particular topographic features at the landing site may therefore offer shielding from part of the incident radiation. Author

Europa; Radiation Dosage; Planetary Magnetic Fields; Energetic Particles; Electron Irradiation; Incident Radiation; Landing Sites

Source: NASA