Passive radar to track space junk above Australian skies

AUSTRALIA has invented an ingeniously simple way to detect and track deadly projectiles in orbit above us. And it could give us an edge in the growing war on space junk.

BUNDLE together Australia’s FM radio stations. Take one supersensitive astronomy radio telescope array. Tune-in to the right frequencies — and suddenly we can see objects 1000km away in space and travelling at 8km per second.

It’s not quite that simple. But it is that efficient.

The Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) are working with Adelaide’s Silentium Defence to turn existing assets into a form of ‘passive’ space radar.

This means it doesn’t rely on a dedicated, new and extensive array of high-power radar transmitters as military and commercial radars do.

It doesn’t need to.

It taps into the FM-band radio waves already being beamed around the country to carry news, gossip, and catchy tunes.

It can do this because of the incredibly sensitive receivers already in place at the Murchison Widefield Array radio telescope in Western Australia (MWA).

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Operated by a consortium of 21 international institutions, it’s part of the planned $1 billion Square Kilometre Array intended to cast new light on the makeup of our universe.

“The reflected signals are received by the MWA, and we use them to track the objects,” John Curtin Professor Steven Tingay says.

Tile 107, or “the Outlier” as it is known, is one of 128 original tiles of this Square Kilometre Array precursor instrument located 1.5km from the core of the telescope. Photographed by Pete Wheeler, ICRAR.

“We can use the radio waves during both day and night, and when it is cloudy, so it can provide 24/7 surveillance in a way that other systems based on optical telescopes cannot.”

As space becomes more and more crowded, it’s becoming vital to track what’s going on up there.

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One wayward scrap, one dead satellite can smash into a multi-billion dollar communications satellite and leave much of the country in the dark. The resulting debris would then cannon about above our skies, further adding to the increasingly deadly game of orbital pinball.

This is why the research team has been awarded funding by the Commonwealth Government’s Defence Innovation Hub.

Silentium Defence chief executive Dr James Palmer said the collaboration with ICRAR-Curtin University astronomers and the MWA showed great innovation.

“The development of space surveillance capability is a significant activity that Australia can offer to the global space industry,” Dr Palmer said.