Archived by Raymond J. Noonan, Ph.D., Health and Physical Education Department, Fashion Institute of Technology of the State University of New York (FIT-SUNY), and SexQuest/The Sex Institute, NYC, for the benefit of students and other researchers interested in the human aspects of the space life sciences. Return to first page for background information on these pages.
Space Radiation
A large percentage of the radiation dosage astronauts receive in low earth orbit occurs during passage through the South Atlantic Anomoly (SAA). The SAA is an area of intense radiation over the south Atlantic Ocean caused by an unusual configuration of the van Allen belts, which normally protect astronauts from ionizing radiation.Imagine the van Allen belts as concentric donuts. They are both centered on the Earth's magnetic axis, which is offset slightly from the geographic (rotational) axis. This means that the inner van Allen belt is closest to the Earth over the south Atlantic. In the SAA, the van Allen belts touch the upper atmospher, and spacecraft moving through the SAA receive a larger dose of radiation.
But shouldn't there be a corrosponding Anomoly in the Northern Hemisphere?
Remember that the Earth's magnetic axis is tilted with respect to its rotational axis, so there is no symmetry involved. The inner belt is both somewhat inclined to the equator and somewhat off-center.
In a loose sense there is an anomaly in the Northern Hemisphere, because while the inner belt is closest to the surface above the South Atlantic, it's consequently farthest away from the surface above the North Pacific. However, there's no particular practical significance to the unusually low radiation levels at orbital altitude over the North Pacific, while the unusually high levels in the South Atlantic are of quite considerable importance.
Questions
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Last modified: Sep 19, 1994Author: Ken Jenks
Raymond J. Noonan, Ph.D. Health and Physical Education Department Fashion Institute of Technology of the State University of New York (FIT-SUNY); SexQuest/The Sex Institute, NYC P.O. Box 20166, New York, NY 10014 (212) 217-7460 |
Author of: R. J. Noonan. (1998). A Philosophical Inquiry into the Role of Sexology in Space Life Sciences Research and Human Factors Considerations for Extended Spaceflight. Dr. Ray Noonan’s Dissertation Information Pages: [Abstract] [Table of Contents] [Preface] [AsMA 2000 Presentation Abstract] |
First published on the Web on June 14, 1998