Tracking Space Junk 22,000 Miles Away From Earth

BUFFALO, N.Y. -- There are thousands of debris objects in space that threaten satellites and future space missions.

Keeping an eye on the debris, even with some of the world's most powerful tracking systems, isn't easy. Thankfully, it's getting easier with the help of John Crassidis, PhD, a University at Buffalo researcher and recipient of the 2012 American Institute of Aeronautics and Astronautics (AIAA) Mechanics and Control of Flight Award.

The award, which includes a medal, certificate of citation and a rosette pin, recognizes his work on space debris and other issues.

"It's certainly an honor," said Crassidis, a mechanical and aerospace engineering professor, who will accept the award in August at an AIAA conference in Minneapolis.

Space debris, also known as space junk, consists of manmade objects that orbit Earth. Examples include everything from defunct spacecraft, such as NASA's UARS satellite that crashed into the Pacific Ocean last year, to flecks of paint corroded from spaceships.

While it's unlikely that debris will fall out of the sky and injure someone, the odds that it will collide with functioning satellites or the International Space Station are increasing, according to the National Research Council.

For example, in 2009 a defunct Russian weather satellite collided with a communications satellite owned by a United States firm. The event produced even more debris, proving a theory known as the "Kessler Syndrome" in which excessive amounts of debris could eventually cause enough congestion in space to block future space missions.

Because there is no cost-effective way to remove debris, researchers such as Crassidis are exploring ways to better track objects with the goal of avoiding future collisions.

Most debris is in low-Earth orbit, a field 100 to 1,200 miles from Earth's surface that includes the International Space Station. Because of its relative proximity, researchers often can determine the shape and mass of objects 10 centimeters or greater in diameter by using telescopes and radar stations. As a result, they can move a spacecraft out of harm's way by firing its thrusters.

According to Crassidis, the same tracking ability isn't available in high-Earth orbit, a field more than 22,000 miles from Earth's surface that is home to satellites used to monitor the weather, make cellular phone calls and for other purposes.

Crassidis illustrated the point by showing a picture of the now-retired space shuttle in low-Earth orbit. The shape of the vehicle is clearly visible. An adjacent slide of high-Earth orbit showed a white dot (unknown space debris) moving in and out of focus on a seeming collision course with stationary white dots (stars).

"We don't know what those objects look like," he said.

That's starting to change, however, because Crassidis is using data from the same tracking systems to develop a computer model that plots the brightness of debris objects as they travel. While still under development, early assessments of the model indicate it will work, he said.

The model could potentially be used by NASA, the Department of Defense and other federal agencies to avoid future collisions in both low- and high-Earth orbit, he said.

Crassidis, who earned his undergraduate, masters and doctorate's degrees from UB, has worked on several NASA satellites. He also designed a software system that NASA uses to detect and find air leaks in the International Space Station.