Thank Van Allen's Belts and Richter's Rockets
Invisible shields above the Earth protect us all from dangerous radiation. New space probes explore how they do it.
When Dr. James Van Allen of the University of Iowa wondered why his geiger counters aboard America’s first Explorer satellites became saturated at certain altitudes, he suspected he had found something important. Large lobed belts of high-energy radiation were named the Van Allen Belts in his honor. The instruments had been mounted in the craft by Dr. Henry Richter, last surviving manager of the Explorer program. He wrote about the discovery in his 2015 book America’s Leap Into Space: My Time at JPL and the First Explorer Satellites. Newly updated with an index, the book (nominated for a Eugene M. Emme Astronautical Literature Award) is an important first-hand account of that historic period in the newly-dawned space age.
Two zones of radiation were identified early on. “This simple picture of the radiation belts persisted for decades until 2012, when a pair of probes was launched to study them in detail,” Space.com says. “This was the first time that two spacecraft simultaneously studied the radiation belts, trading information with each other to build a bigger picture.” The findings are exciting and vital to life on Earth:
Data gathered by the probes also showed that the radiation belts shield Earth from high-energy particles. “The barrier for the ultrafast electrons is a remarkable feature of the belts,” study lead author Dan Baker, of the University of Colorado in Boulder, said in a statement.
“We’re able to study it for the first time, because we never had such accurate measurements of these high-energy electrons before.”
The Van Allen Probes have revealed the dynamic nature of our space shield. “Space tsunamis” from solar outbursts called coronal mass ejections cause rapid changes in the belt structure, accelerating electrons to near light speed. Engineers watched one particular reaction when the two probes were monitoring different positions.
“The spacecraft measured a sudden pulse of electrons energized to extreme speeds — nearly as fast as the speed of light — as the shock slammed the outer radiation belt,” NASA wrote at the time. “This population of electrons was short-lived, and their energy dissipated within minutes. But five days later, long after other processes from the storm had died down, the Van Allen probes detected an increased number of even higher energy electrons. Such an increase so much later is a testament to the unique energization processes following the storm.“
Lessons learned from these reactions help engineers design better radiation protection for astronauts, the article says.
Dr. Henry Richter is an American VIP who is still active at age 88 with his wife (age 90) in southern California. He was instrumental in the design of the Explorer, Ranger and Surveyor spacecraft at JPL, and development of the Deep Space Network. He is also a Christian and a young-earth creationist. The CEH editor is working with him on a new book that will share wonders of creation and end with his story of how he came to Christ. The draft is currently being reviewed by the publisher and may be available late this year or in 2017; watch for announcements in these pages.
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