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Scientist educates public about space and radiation

NASA's Van Allen Probes topic of conversation during lunch series

POSTED: January 14, 2014 1:00 a.m.

When David Yenerall asks the group of adults sitting in the Elachee Nature Center if they have any questions, hands immediately shoot into the air.

Yenerall, an instructor of physics and astronomy at Georgia Perimeter College, spoke to the group Thursday afternoon about the Van Allen Probes, two NASA spacecraft measuring the radiation belt surrounding Earth at the center’s Natureversity Brown Bag Luncheon.

Rather than asking for clarification on the science Yenerall covered, many questions started with “what if.”

Yenerall said he enjoys trying to answer questions that have to do with outer space because he hopes to help others learn more about science, even if he can’t give a definitive answer.

He said scientists don’t know a lot of things about how the universe works. But with the help of the Van Allen Probes, which were launched in August 2012, scientists are able to learn more about the sun’s influence on Earth and space by studying Earth’s radiation belts. The instruments measure the effect of solar storms on the belts and in essence allow scientists to understand space “weather.”

Changes in the radiation belts can have a harmful effect on satellites and astronauts. Yenerall said the amount of radiation a person can be exposed to in a lifetime is limited.

“Young astronauts are allowed to be in unshielded areas on the international space station for shorter periods of time than older astronauts,” the scientist said. “Because the total amount of time that (older astronauts) are going to be bathed in radiation will be a shorter amount of time because these younger astronauts will be doing this throughout their career. They have to conserve how much radiation they can get per year.”

Yenerall said the study of the radiation belts is particularly interesting to him because it could also open up new areas of understanding for other planets in the solar system such as Jupiter, Saturn, Uranus and Neptune, which also have radiation belts.

“This is not something that’s unique throughout the Earth,” Yenerall said. “The Jovian planets, any planet with a strong magnetic field, has these belts. It’s fundamental physics. They want to understand how charged particles operate in the magnetic field. This is science we can use here on Earth to understand the universe better. Also they want to understand these radiation belts and how to mitigate damage to our property and to human beings in this environment.”

Several people took the opportunity to ask about Mars and how it compares to Earth.

Yenerall said when radiation, or charged particles, move from the sun through space they become “energized” when they hit our magnetic field, which Mars lacks.

“It’s a dance,” Yenerall said. “So when the planet doesn’t have a magnetic field, (radiation) will bombard the planet. Some of (the particles) will go around but it will slowly erode the atmosphere. Like with Mars there is very good evidence that there were large bodies of flowing water. In order for water to stay around, especially on a planet as small as Mars is, it would have to have a strong, thick atmosphere. It would also have to have a magnetic field to have this atmosphere. ... It appears that Mars at one time had a magnetic field, but it went away very early in its history, 4-plus billion years ago.”

Yenerall said it’s “frightening to think about” how the planet might have lost it’s magnetic field and what it would mean for Earth if the same were to happen.

“These are things that could happen here on Earth,” Yenerall said. “I don’t know if we could stop them or not, but I would like to at least be able to understand the mechanism and give it our best shot.”

Ellen Heil of Chestnut Mountain attended the lecture though she admits she had only a “mild interest” in the topic. She said she enjoys the informality of the setting and the feeling of freedom to ask anything.

“It was just something to learn about,” Heil said. “I think he did an excellent job. I enjoy this. They have some great speakers.”

Two more lectures are scheduled for the monthly series, which begins at 12:30 p.m. on the second Thursday of the month. A $10 donation is requested, and attendees are asked to bring a sack lunch.

Peter Gordon, education director, said the program that started last year has been popular among adults.

“We’ve had a lot of fun with it,” Gordon said. “There are a whole lot of speakers like David who came this year and last year that are just fascinating.”


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