HUNTSVILLE, Ala. – 30 JAN 13
Sam Castle: When You Wish Upon a Shooting Star
What are shooting stars but meteors fragmenting as they fight their way through Earth’s atmosphere? For Sam Castle, a junior physics major at Davidson College, they were a wish come true. Although he never thought that working for NASA was a possibility, he received the call at the end of summer “just moments after stepping off the Appalachian Trail in Hot Springs, North Carolina.” He was ready to begin his fall semester, and only had five days to decide whether or not to delay his graduation, but ultimately, this opportunity was too good to pass up.
Before coming to NASA to intern in Marshall Space Flight Center’s Meteoroid Environments Office (MEO) with NASA meteor expert Dr. Bill Cooke, Sam Castle thought that all meteors were boulders hurtling through space. However, Dr. Cooke and his team opened his eyes this fall to the world of meteoroids, meteors, fireballs, and meteorites.
For his main project, Castle collected and analyzed data on fragmenting meteors. “NASA’s Meteoroid Environments Office, where I work, operates a network of cameras in the southern U.S. which automatically detect meteors every night,” said Castle. “Using the video captured by these cameras, I was able to find events where the meteor clearly broke apart suddenly, producing a strong flash of light. Analyzing the motion and photometry of these meteors, I determined the mass of the meteor body before and after fragmentation and the mass of an average fragment particle.”
From his analysis, Castle was able to provide insight into the structure of the meteor as well as the process of its fragmentation. He explained, “When a meteor fragments, it does not simply break apart into a couple of chunks. It also ejects thousands of tiny pieces, likely resembling a cloud of dust. This hints to the structure of meteoroids — they are typically not just a huge chunk of solid rock; rather, they may have boundary lines, consisting of fine, grainy particles.”
While at Marshall, Castle was also given the opportunity to study fireballs, or extremely bright meteors. He determined fireball trajectories, altitudes, and velocities among other things, and MEO could use his trajectories to seek radar signals to lead to evidence of meteorite falls. He even got to physically search for meteorites in the local area. Castle revealed, “On October 30, a fireball dropped meteorites in Alabama…. [T]his is the first recovered meteorite fall in Alabama since the Sylacauga meteorite in 1954.”
Outside of his assigned duties, Dr. Cooke and the Marshall team exposed Castle to the rich history of NASA’s Apollo Missions. In an interview with The Davidsonian, he indicated, “Every Wednesday during lunch, my department watches part of a series of movies about the Apollo missions. It’s inspiring and wonderful.”
After graduation, Castle hopes to go abroad to gain a better understanding of as well as contribute to international cooperation. He also would like to teach and inspire the next generation of STEM high school students. In regard to NASA, Castle postulated, “I could definitely see myself working again as a fulfilled and invigorated NASA employee. I am fascinated by all that I have learned, enriching my passion for space.”