Selections from the space.com article on ATLAS (for the Asteroid Terrestrial-impact Last Alert System)...
An early warning system that could give Earth a week's notice or more before a space rock destroyed a city would cost only $1 million per observatory, its leading proponent suggests.
Given current technologies, this lead time would not be enough to mount a mission to deflect the incoming object, but it could be enough to evacuate the area under threat.
Astronomer John Tonry at the University of Hawaii mentioned a near-miss in 2009 as he stressed the need for an early warning system against cosmic impacts.
According to estimates by Tonry and other researchers, the rate of impact by asteroids at least 460 feet (140 meters) long is just once per 20,000 years or more — but the smaller the rock, the larger the risk. A roughly 160-foot-long (50 meters) object like the one that devastated the Tunguska area in Russia in 1908 is likely to impact Earth about once every millennium, while a 65- to 100-foot-long asteroid (20 to 30 meters) should strike once every century.
The National Research Council estimated a 160-foot-long object would cause an average of 30,000 deaths.
Tonry details his analysis in a paper set to appear in the January issue of the Publications of the Astronomical Society of the Pacific.
The network the researchers propose, dubbed ATLAS (for the Asteroid Terrestrial-impact Last Alert System), would consist of two observatories roughly 60 miles (100 km) apart that together would scan the visible sky twice a night. Each observatory would house four relatively small telescopes some 10 inches (25 cm) in aperture, as well as a camera for each telescope. The distance between the observatories would provide a way of separating nearby and distant moving objects, and the system would be able to help pinpoint the location and time of an impact to a few miles and a few seconds.
Each telescope and each camera would cost roughly $50,000. The software would take up the lion's share of expenses, bringing the cost for each observatory to $1 million. Tonry also projected $500,000 annually for staff, maintenance and other operating costs. He and his colleagues have submitted a $3 million proposal to NASA to build two observatories and operate them for two years.
ATLAS could provide three weeks' warning for 460-foot-long objects and one week's notice for 160-foot-long impactors. The smaller the object, the less warning there would be; a 65- to 100-foot-long asteroid might draw two or three days warning, while 33-foot-long objects might get one.
As currently proposed, ATLAS would detect more than half the impactors longer than 160 feet, and nearly two-thirds of those 460 feet long. The chances of detection go up with more telescopes, Tonry said, which would allow ATLAS to compensate for cloudy weather or lack of coverage in the Southern Hemisphere. Still, ATLAS' detection rate would never go higher than roughly 75 percent, since it could spot objects coming from the blinding direction of the sun.
Link: Article
Link: ATLAS website
