Low-orbit satellites may soon be able to dodge space debris, thanks to a collaboration between scientists from the University of Calgary and the University of Alaska Fairbanks.
Using data from CASSIOPE a UCalgary-operated satellite the scientists have discovered that debris floating through the near-Earth ionosphere produces plasma waves that can be detected with a radio receiver instrument onboard the satellite.
The ultimate goal of the finding is to build an automated detection system on satellites that would detect space debris and move the satellite out of a collision course.
"We want the satellites to be able to see the object, predict where it is going and, if it's in the path of the satellite, move out of the way," explains Andrew Howarth, MSc'06, project and operations manager of CASSIOPE, which is within the Department of Physics and Astronomy in the Faculty of Science.
Growing risk of low-orbit collisions
Space debris has become increasingly problematic over the years, with some satellites blowing apart to create even more debris. Combine this with the ever-increasing number of satellites nearly 8,000 in low-Earth orbit the potential for collisions increases exponentially.
"One object becomes 500, and then those 500 objects have a larger chance of interacting with other debris and satellites," says Howarth.
Travelling at speeds up to 27,000 kilometres an hour, this debris can have an impact energy equivalent to a small hand grenade. Damage from space debris has already been observed on the Canadarm and other satellites.
"Something very small can punch holes in critical systems on your satellite or the space station, things you'd be interested in keeping whole," explains Howarth.
The North American Aerospace Defence Command, or NORAD, tracks all objects in low-earth orbit using an array of radars on the ground. However, it can only detect objects 10 centimetres or larger.
This is where Howarth and the team come in.
The low-orbit advantage
In 2021, a few collaborators asked the CASSIOPE team to turn on its radio receiver instrument to see if they could detect radio waves of objects as they passed by. They theorized that charged objects in the ionosphere would emit plasma waves.
They started off with large objects, turning on the radio receiver as they passed within 10 kilometres, with the result being an increase in wave power when some objects passed by.
With a proof of concept, a project was put together under the leadership of Dr. Paul Bernhardt from the University of Alaska Fairbanks and funded by Intelligence Advanced Research Projects Activity to continue to refine the plasma wave tracking.
The project brings together modellers and the CASSIOPE team. As the modellers put together simulations of what they think will happen, the CASSIOPE team is able to provide the data either proving or disproving the models.
The CASSIOPE satellite is the only satellite in low orbit that can measure this data due to its radio receiver and the elliptical orbit it travels on, allowing it to interact with the orbits of space objects at different altitudes.
What can we learn from plasma waves
Plasma waves come in all kinds of modes, similar to electromagnetic waves on Earth, that behave differently in different conditions. The team is currently investigating these different modes of plasma waves under a variety of factors that make it difficult to determine exactly which kinds of waves are being emitted.
Once they figure out which waves are emitted, the next phase of the project will be the development of a sensor that can detect the direction and amplitude of the waves to detect where the objects are.
While Bernhardt is helming that part of the project, Howarth and team will continue to provide data and satellite operations expertise.
This is just the latest mission for the CASSIOPE satellite, which was intended to be used for 18 months but has been orbiting and collecting data for almost 12 years now.
CASSIOPE satellite keeps on going
From better understanding space weather to filming auroras, the satellite has proven its adaptability and utility to all sorts of scientific missions.
"We've been able to pivot, and we've found some new science that we had never planned to do," says Howarth.
"Being up there so long, we've established connections with lots of scientists, so when they think of something they come to us to see where we can help."
