As odd as it may sound, popular music can help detect space debris – at least pop-music broadcast via radio waves by terrestrial radio stations. Radio waves transmitted by ground-based stations find their way to space where they are reflected by orbiting space junk and bounce back to Earth. Back on Earth, these waves can be intercepted and their characteristics analyzed to determine the distance and size of objects that reflected them.
Australian researchers have proved such a concept really works. However, they needed a very powerful ear to be able to listen to the reflected pop music – the Murchinson Widefield Array (MWA).
Opened earlier this year in western Australia, the $51 million observatory, one of the precursors of the planned Square Kilometer Array project, listens to low-frequency radio signals in the range between 80 to 300 MHz. It was designed to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the Sun, heliosphere and the Earth’s ionosphere.
With a study recently published in the Astronomical Journal, new avenues are now opening in front of the Murchinson researchers as the telescope might join the space debris mitigation front.
“The MWA was designed to be the most powerful low frequency radio telescope in the Southern Hemisphere and this was our chance to test its capabilities,” said Professor Steven Tingay, an astronomer at Curtin University.
“We have shown that we are able to detect approximately 10 pieces of space junk simultaneously. Over time this means we are in a position to monitor a significant fraction of the space junk that is in Earth orbits,” he said.
Tingay believes the array, consisting of 2,048 dual-polarization dipole antennas arranged in 128 formations of four-by-four tiles, could serve as a basis for an elaborate space debris monitoring system.
“An early warning system has the potential to protect billions of dollars’ worth of vital infrastructure orbiting the Earth but also prevent collisions that will result in even more space debris being generated, such as what happened in the case of the Iridium 33 satellite in 2009,” Tingay said, taking the collision between the functioning American satellite and an already dead and out-of-control Russian spacecraft Cosmos as an example. The collision not only destroyed both satellites but also generated thousands of dangerous fragments that ended up hurtling through space at enormous velocities without any control whatsoever.
“Because the telescope has such a large field of view, monitoring vast patches of the sky at any given time, we can simultaneously image hundreds of these objects every day and track them for long enough to determine their orbits,” Tingay said.
“We can do all this at the same time as our primary mission. That is, to look way back into cosmic time.”
The idea to use the MWA for tracking space debris came from an earlier study by Ben McKinley, an astrophysics PhD student at the Australian National University, who was able to image the Moon using reflected FM signals and calculate the likelihood that alien civilizations were listening in on us.
Watch Professor Tingay speak about the project in the video below: