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