 |
Carolin Frueh, an associate professor of aeronautics and astronautics, enjoys solving math problems that just keep getting harder the more that she discovers about how space junk behaves. (Purdue University photo/Rebecca McElhoe) |
Much of the space junk orbiting Earth won’t clean up itself – or tell you how it got there.
Purdue University’s Carolin Frueh and her team are investigating what causes spacecraft to become space junk. Their findings are revealing ways to prevent spacecraft from breaking apart into thousands of pieces of debris that pose a threat to space stations and satellites.
Since 1957, there have been more than 570 incidents of spacecraft fragmenting in Earth’s orbit because they exploded, detonated or collided with each other.
Companies have begun testing technology that may help clean up the mess, but it’s not often clear how spacecraft fragment in the first place. Frueh’s team has undertaken the extremely complicated math needed to get answers.
“I like harsh, challenging problems that don’t have obvious solutions,” said Frueh, an associate professor in Purdue’s School of Aeronautics and Astronautics. “Because space objects are too far away to easily do experiments on or with them, we just observe these objects with a telescope. But even then, we don’t have much data on the objects, as they are not always visible or they’re too small to detect. The question is, ‘What can I still find out about this object with the little data that I can collect?’”
Unraveling the mystery behind a spacecraft’s explosion
Some of the biggest culprits of space debris resulting from fragmentation are upper stages of rockets. The upper stage, which burns last in a mission, tends to stay in space after propelling satellites into orbit. U.S. spacecraft are recommended to deorbit within 25 years of end-of-mission, but not all comply.
A spacecraft can shatter into hundreds of pieces – many the size of a quarter inch or smaller. At altitudes of about 22,000 miles above Earth, Frueh and her collaborators track fragmentation pieces larger than six inches. The problem is speed: Space debris tends to travel faster than a bullet out of a gun (upwards of 15,000 mph). This speed makes even smaller pieces more harmful when they collide with other objects.