joew@cgdco2.ucar.edu (Joe Wagner) (08/17/89)
Further comments on: >>article <3929@ncar.ucar.edu> gary@cgdra.ucar.edu (Gary Strand) asking: >>How much radiation does the shuttle receive in a high-latitude (as in the >>August 8-13 secret mission) compared to a lower-latitude orbit? The answers from Spencer at U of Toronto Zoology were good: >It's not very significant at the latitudes the shuttle reaches in a launch >from KSC....unless it gets far enough south to enter the South >Atlantic Anomaly....The SAA is an area where the inner Van Allen belt >is unusually close to Earth, due to asymmetry in the Earth's magnetic >field....But even the SAA isn't really a significant issue unless >you're going to be up for months, as I recall.... But he did not mention the greatest radiation threat of all -- solar particle events from large flares. James Michener's book "Space" was accurate in portraying the lethality of these events. The polar caps of the earth (from the auroral oval up to the poles) are open to the same levels of radiation as found in free space. These oval boundaries lie near the arctic/antarctic circles when there is no geomagnetic storm. In a geomagnetic storm, the polar cap areas expand with the aurora down to "the lower 48" states. Big solar flares, like the one reported in the papers for August 12, can fill the polar caps with high energy particles (radiation). Probably, NASA or the National Weather Service can give more information and also know the situation during the shuttle mission. ------------------------------------------------------------------------------ Joe Wagner joew@cgdisis.ucar.edu