Technology that ‘de-twinkles’ stars is being used to pinpoint manmade space junk and avoid devastating collisions like those dramatised in the movie Gravity.
Australian company Electro Optic Systems, based on Mount Stromlo in Canberra, is using adaptive optics and pulsing lasers to locate detritus too small for conventional radar. Ultimately, the company hopes to use similar lasers to remove the debris from orbit.
Adaptive optics helps the pulsing lasers to cut through the Earth’s atmospheric turbulence, which distorts and scatters light, by using a second orange-coloured laser to illuminate sodium atoms in the upper atmosphere.
This creates an artificial ‘guide star’, or a bright spot of known size and position, which can be used to track and compensate for the atmospheric distortions.
“Normally the beam spreads out to 10 or 20 metres in width, but with adaptive optics we can focus it to within a metre,” says François Rigaut, head of the Adaptive Optics Group at the Australian National University that developed the technology.
These distortions are also what causes the twinkling of stars, so it’s no surprise that the ANU technology will also be used in the world’s biggest telescope, the Giant Magellan Telescope, to be constructed in Las Campanas, Chile.
Just as its namesake Ferdinand Magellan navigated by the stars 500 years ago, this new telescope will use four laser guide stars to constantly adjust its mirrors, making it more powerful than even the Hubble Space Telescope.
“It will be able to see planets orbiting other stars and even measure the makeup of their atmosphere,” says François. “It’s very exciting.”