Sam Castle '14 spent the fall semester studying those familiar flashes of light that streak across the night sky-meteors! Castle conducted research on "shooting stars," as they are colloquially known, from late August through mid December as his job during an internship with NASA at the Marshall Space Flight Center in Huntsville, Ala.
Castle explained that shooting stars are rocks floating through space that are captured by Earth's gravitational field and burn up at they fly through the atmosphere, yielding the characteristically bright and brief flash of light at approximately 75 to 50 miles above the Earth's surface.
Castle said, "Most meteors we see are produced by surprisingly small particles with large kinetic energies because of their high speed-sometimes as fast as 72 kilometers per second."
NASA has a network of eight cameras located in Alabama, Georgia, Tennessee, and New Mexico that record meteors as they fall, and Castle studied the images and data they captured. "It was great," Castle said. "I came to work in the morning and the computer had collected great meteor data for me."
Castle's research project more specifically concerned meteors that exploded. "I studied whether or not it broke into millions of tiny pieces or big chunks, which helps us learn more about the structure of meteors," Castle explained. A meteor exploding into big chunks suggests a composition of stone or metal, whereas those that fragment into tiny pieces indicate a grainy composition of loosely held particles.
Castle was also studying meteoroids -- space rocks before they enter Earth's atmosphere. "Knowing meteoroid structure tells us something about the nature of the meteoroid's parent body, which may be a comet, asteroid, moon, or planet," said Castle. "Learning about the structure of meteoroids also tells us something about how they were formed."
Castle said the study of meteors and meteoroids is important to NASA's space program. "Even small meteoroids can wreak havoc on satellites or spacecraft," he said. "For the success and safety of missions, it is very important to study meteoroid shielding, and the probability of impacts."
Castle noted that NASA satellites Olympus and Chandra were both struck by meteoroids, and the collision with Olympus proved fatal.
Castle's work at NASA gained the attention of the "meteor community" of international scientists and astronomers. He said, "We studied a huge fireball seen over Scotland on September 21, 2012, which some thought 'bounced' and orbited around Earth before reentering the atmosphere over Canada. There was a big buzz in the meteor community when it happened. So another intern and I analyzed the video and determined that these were two separate meteors. The 'big dog' meteor experts agreed and told us 'good work!'"
Castle applied for an internship for the summer of 2012, but NASA offered him a fall internship instead. He was leading a backpacking trip for Davidson's summer Odyssey program when he got the news. "I told them 'that's great!' but I can't really talk right now. I have work to do."
Castle's found his job at NASA quite rewarding. "It was exciting to learn about our space program, meet the people involved and see the technology NASA is working on," he said. The internship gave him the opportunity to attend the Wernher von Braun Memorial Symposium in Huntsville, which featured presentations by Todd May, manager of NASA's Space Launch System, and Paul Allen, cofounder of Microsoft. "I've never been around that many engineers in my life!" he said.
Castle's internship concluded following his final research presentation to NASA scientists.
Castle said the internship fed his growing love of physics, his major at Davidson. "I think it's important to learn about the universe that we live in," he explained. "Research in physics provides insight into big questions, like how did we end up on earth, how did the planets form, is there life on other planets?"
"I'm all for space exploration, I want go find the aliens!" Castle quipped. "I think they're out there, though the chances of finding them are slim."
After graduation, Castle would like to continue his work on space, possibly from an international perspective. "I'd like to learn more about Russia or China's space program, understand how they are different than NASA, and investigate how they can work better together," Castle said.