The Asteroid Terrestrial-impact Last Alert System (ATLAS) is a proof of concept astronomical survey system for early detection of dangerous asteroids—for ones within a few weeks of impacting Earth. The project was developed at the University of Hawaii with US$5 million funding from NASA.
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Deployed in 2015, the automated system provides a one-week warning for a 45 metres (150 ft) diameter asteroid, and a three-week warning for a 120 m (390 ft) one, as long as their radiant is not too close to the Sun. By comparison, the February 2013 Chelyabinsk meteor impact was from an object estimated at 17 m (60 ft) and its radiant's closeness to the Sun put it in the blind zone of an ATLAS-like system.
The first telescope became fully operational at the end of 2015. ATLAS may be expanded geographically to several other locations in both hemispheres to provide continuous coverage, resilience to bad weather, and additional information on the orbit from the parallax effect. Additionally, ATLAS will look for dwarf planets and supernovae.
Naming
The Last Alert part of the system name refers to the fact that smaller asteroids will not be found in time for potential deflection, but that days or weeks of warning would be provided in order to evacuate and otherwise prepare a target area. According to ATLAS project lead John Tonry, "that's enough time to evacuate the area of people, take measures to protect buildings and other infrastructure, and be alert to a tsunami danger generated by ocean impacts".
Design and operation
The full ATLAS concept consists of eight small telescopes, each fitted with cameras with resolution of 100 megapixels. The first two telescopes, ATLAS1 and ATLAS2, are sited in the Hawaiian Islands and ATLAS1 is operational. The eight telescopes will scan the visible sky twice per night, much more quickly but in much less depth than larger surveying telescope arrays such as University of Hawaii's Pan-STARRS. ATLAS1 alone scans the accessible part of the sky every 4 nights, weather permitting.
NASA's Near Earth Observation Program provided a US$5 million grant, with $3.5 million covering the first three years of design, construction and software development, and the balance of the grant to fund the systems operation for two years following its entry into full operational service in late 2015.