Wayward asteroids tumbling through space pose one of the most credible space-originating threats to life on Earth. Scientists have calculated that an asteroid at least six-tenths of a mile (1 kilometer) across pummels Earth once every 100,000 years.
As a result, a handful of near-Earth asteroid sky surveys are tracking the tumbling rocks to identify those whose paths through space could send them hurtling into the Earth. Although these detailed surveys are tracking many asteroids, the Earth is still at risk of being blindsided by a careening asteroid uppercut from the south.
That's because there has been no dedicated asteroid sky survey looking into space from the Southern Hemisphere since 1996, when the Australian government cancelled the only official asteroid survey covering all of the southern sky.
To open up the blind spot, astronomers at the Australian National University have volunteered to refurbish a little-used 26-inch telescope at the Siding Spring Observatory near Coonabarabran, Australia, a town some 200 miles northwest of Sydney in New South Wales.
During the next two years, astronomers will equip the telescope with high-resolution detector arrays and computers to allow it to track near-Earth asteroids. In the meantime, they are using a 40-inch (1-meter) telescope at Siding Spring to track near-Earth asteroids discovered by observers in the Northern Hemisphere.
Once the work is done, the astronomers will be able to scan the entire southern sky in search of potentially-threatening asteroids.
The search will be patterned on the Catalina Sky Survey, an asteroid watch operated by astronomers at the University of Arizona using a 16-inch telescope in the Santa Catalina mountains near Tucson. Steven Larson, who directs the Catalina program is visiting Australia this week to help the Australian National University team plan the telescope upgrades.
The new Australian survey will fill a gap in the observations of NASA's Near-Earth Object Observation Program, which seeks to catalog 90 percent of the potentially hazardous asteroids larger than 1 kilometer in diameter during the next decade.
If an asteroid that size smacked Earth, "everybody would suffer in some way from it," said Harvard-Smithsonian astronomer Brian Marsden. Marsden is director of the Minor-Planet Center in Cambridge, Mass., an operation that catalogs discoveries and calculates the paths of near-Earth asteroids and comets.
A ground impact of a kilometer-size meteorite on Earth would destroy a large area near the impact, cause fires in the surrounding region, and fill the atmosphere with dust, Marsden said. A large enough object could pollute the atmosphere with enough debris to block sunlight for months, destroying agriculture and causing mass starvation.
In addition to the project at the Australian National University, the Perth Observatory in western Australia also recently announced plans to conduct a search for near-Earth asteroids, Marsden said.
"I think it's great that the Southern Hemisphere is waking up again to do searches as well as the follow up," Marsden said, adding that the Catalina Sky Survey has been very effective during the past two years. "If the success of the Catalina program is anything to go by, I think we can expect great things of this new program in the Southern Hemisphere."
