Asteroid Terrestrial-impact Last Alert System
This article needs to be updated.(February 2016)
|Survey type||astronomical survey|
|Observatory code||T05, T08|
The Asteroid Terrestrial-impact Last Alert System (ATLAS; Observatory codes T05 and T08) is an astronomical survey system for detection of near-Earth objects a few weeks to days before their impacting Earth. The project was developed at the University of Hawaii with US$5 million funding from NASA, and its first element was deployed in 2015. The first telescope became fully operational at the end of 2015, and the second one in March 2017. Replacement of the initially substandard Schmidt corrector plates of both telescopes in June 2017 improved their image quality to its nominal 2 pixels width. 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. As a by-product of its main design goal, ATLAS also looks for dwarf planets, non-impacting asteroids, variable stars, and supernovae.
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, and for the current Hawaii-based system, not too far into the Southern hemisphere. By comparison, the February 2013 Chelyabinsk meteor impact was from an object estimated at 17 m (60 ft). Its radiant's closeness to the Sun put it in the blind zone of any ATLAS-like system, but ATLAS would detect a similar object arriving from a dark direction approximately one day in advance.
The Last Alert part of the system name refers to the fact that ATLAS will find smaller asteroids much too late in time for potential deflection, but that the days or weeks of warning that would be provided are enough 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". Much of the limited damage and injuries caused by the 17-m Chelyabinsk meteor impact were from window glass broken by its shock wave, and with advance warning those could have been much reduced by actions as simple as propping all windows open before the impact and staying away from them.
Design and operation
The full ATLAS concept consists of eight 50cm diameter f/2 Wright-Schmidt telescopes, spread over the globe for full-sky and 24h/24h coverage, and each fitted with a 110 Megapixel CCD array camera. The current system consists of two such telescopes operating on Haleakala and Mauna Loa in the Hawaiian Islands, ATLAS1 and ATLAS2. A major feature of these telescopes is their large 7.4° field of view - about 15 times the diameter of the full moon. With this system the whole night sky visible from Hawaii can be imaged with about 700 separate telescope pointings. At 20 seconds per exposure plus 5 seconds for readout, each ATLAS telescope scans the whole visible sky twice each night, reaching to apparent magnitude 20. This is astronomer-speak for "respectably but not extremely faint", and it is the equivalent to the light of a match flame in New York viewed from San Francisco. ATLAS therefore scans the visible sky in much less depth, but much more quickly, than larger surveying telescope arrays such as University of Hawaii's Pan-STARRS which goes approximately 40 times deeper but only every few days.
NASA's Near Earth Observation Program initially 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. A further NASA grant funds continued operation of ATLAS until 2021. 
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- University of Hawaii at Manoa's Institute for Astronomy (18 February 2013). "ATLAS: The Asteroid Terrestrial-impact Last Alert System". Astronomy Magazine. Retrieved 2013-02-22.
- Henry Weiland (18 February 2013). "New Schmidt Correctors Installed!". Retrieved 2017-10-12.
- Atlas: How it works. Asteroid Terrestrial-impact Last Alert System.
- Clark, Stuart (20 June 2017). "Asteroids and how to deflect them". The Guardian. Retrieved 2013-02-22.
- Heintz, Jim; Isachenkov, Vladimir (15 February 2013). "Meteor explodes over Russia's Ural Mountains; 1,100 injured as shock wave blasts out windows". Postmedia Network Inc. The Associated Press. Archived from the original on 13 May 2013.
Emergency Situations Ministry spokesman Vladimir Purgin said many of the injured were cut as they flocked to windows to see what caused the intense flash of light, which was momentarily brighter than the sun.
- ATLAS Telescope 2 Installed on Mauna Loa, Ari Heinze  Retrieved April 7, 2017.
- Oliver, Chris. ATLAS Project Funded by NASA, Nā Kilo Hōkū (newsletter), Institute for Astronomy, University of Hawaii, No. 46, 2013, p. 1. Retrieved August 2, 2014.
- ATLAS Update #18: 2017 March  Retrieved April 14, 2017.