ASTEROID ALERT
THE PREDICTION THAT PLANET EARTH IS DUE TO BE HIT BY AN ASTEROID HAS SCIENTISTS PREPARING FOR AUSTRALIA’S FIRST SPACE STATION, WRITES JENNIFER DUDLEY-NICHOLSON
Nine days from now, an asteroid as large as 1.2km wide will hurtle around Earth at 34 kilometres per second, close enough to be classified as “potentially hazardous” to life as we know it. The high-velocity space rock is one of 17,000 asteroids tracked by NASA, 8000 of which are 100m wide or larger, and big enough to destroy a continent.
Mercifully, Asteroid 2002 AJ129 is due to fly safely past our planet on this occasion and, NASA says, poses no chance of hitting Earth in the next “100 years”. Other asteroids are not so innocuous, however, and scientists predict Earth is due for a “reasonablesized impact”.
While American and European space agencies are monitoring the potentially planet-threatening situation, Australian researchers are taking part too, with projects including a new asteroidhunting radar system to give humans a “much better chance than the dinosaurs”, and a proposal to shoot highpowered laser beams into space to move man-made debris out of harm’s way.
The moves come before the federal government reveals how much funding it will allocate to Australia’s first space agency, a development expected in this year’s Budget, but Senator Simon Birmingham warns it will be small and “not NASA”.
The risk of asteroids colliding with Earth has long been feared and exploited by Hollywood blockbusters, from 1958’s The Day The Sky Exploded to that time Bruce Willis saved us all in Armageddon. But asteroids are far from science fiction.
In 1908, a 50m rock hit Tunguska, Siberia, flattening 2000sq km of forest.
And just five years ago, a 20m near-Earth asteroid skimmed the surface of the atmosphere over Chelyabinsk, Russia, creating a shockwave that injured 1200 people and blew the windows out of almost 5000 buildings.
Disturbingly, that asteroid had not been tracked, Canberra Deep Space Communication Complex spokesman Glen Nagle says, and “that day people were looking in the opposite direction”.
“Had that thing not just grazed the atmosphere but come straight down, a city the size of Tel Aviv might not even be here today,” he says.
A similarly untracked asteroid was believed to be behind the flash, bangs, and tremors seen near Gladstone in September 2016, though no one was injured.
Other top risks include a 32m asteroid due to visit in 2026, according to the European Space Agency, and a 140m asteroid due to pass near Earth in 2057. Nagle says the chance of impact is probable, though its arrival is hard to predict with certainty.
“We’re probably due for a reasonable-sized impact, probably some time over the next 10 to 40,000 years, just based on the cycle that we know of,” he says.
“It could happen tomorrow, it could happen 100,000 years from now, we just don’t know. If we don’t look, we’ll never know, and then we’ll be the dinosaurs.”
Nagle, whose organisation is part of NASA’s Deep Space Network and contributes to its research, says the American space agency tracks most known asteroids with its 70m Goldstone satellite dish in California, using highpowered radio signals.
Australia, by contrast, doesn’t have a permanent, dedicated radar system, he says, but that could change.
The Canberra outfit has already tracked three asteroids as part of “early tests” using the Australian Telescope Compact Array in Narrabri, NSW, and there are plans to expand it in the coming years.
“In the early 2020s there’s potential for a system to be used here in the southern hemisphere,” he says.
“It’s something we’re looking to bring in in future, and of course that will need the support of NASA and will need to incorporate budgets.”
Nagle says tracking asteroids from Australia is important as they are only within sight of an observatory for a few hours, giving astronomers a limited time to accurately assess their orbit.
“It would be like seeing a car drive for three minutes and trying to predict where its destination will be,” he says.
There’s another significant challenge to protecting the Earth from asteroids, too — currently humans have no way to stop them.
Blowing an asteroid up, Bruce Willis-style, is not an option, Nagle says, as “that just creates more pieces”, and they instead need to be nudged off-course.
To this end, NASA intends to launch the Asteroid Impact and Deflection Assessment in 2020, which involves sending a spacecraft on a crash course with the 65803 Didymos asteroid system. NASA’s OSIRIS-REx spacecraft is also due to land on an asteroid, Bennu, in December this year, where it will spend a year analysing and mapping the asteroid and collecting samples before its return.
Scientists hope by studying the carbonaceous asteroid, the $US800 million mission will reveal what they’re made of, to help scientists better target them and understand more about the formation of our solar system.
Another danger flying through space that Australians are monitoring is one of our own creation. There are more than 170 million pieces of space junk too small to track, 500,000 pieces the size of a marble, and 30,000 pieces the size of a softball or larger.
Even tiny pieces of space junk can be seriously dangerous, though. A fleck of paint, for example, recently chipped the window of the International Space Station.
The Australia Space Environment Research Centre is one organisation attempting to track this out-of-control debris, using a telescope at the Mt Stromlo Observatory, just outside of Canberra.
Chief executive David Ball says Australia should take a leading role in tracking space junk as it endangers everything from communication systems to GPS-based navigation and climate-monitoring systems.
“Australia, as a nation, is very reliant on space for a number of applications,” he says. “None of us want to see anything terrible happen up there. The issue is how do we avoid collisions? If you have a major collision that will put debris around a certain orbit, which will mean you can’t use that for satellites.”
Ball says Australia needs to develop a “traffic management system” for space junk, and it should include using a highpowered laser to knock debris off-course, a research project the Centre is developing and one that is due to be “up and running within the year”.
If we don’t look we’ll never know. CSIRO’s Glen Nagle