[6][7] The 37 million years old asteroid impact that excavated the Mistastin crater generated temperatures exceeding 2,370 °C, the highest known to have naturally occurred on the surface of the Earth.
[8] Throughout recorded history, hundreds of Earth impacts (and meteor air bursts) have been reported, with some very small fraction causing deaths, injuries, property damage, or other significant localised consequences.
[10] Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years, with as much kinetic energy as the atomic bomb dropped on Hiroshima (approximately 16 kilotons of TNT).
One of the best-known impacts in historical times is the 50 meter 1908 Tunguska event, which most likely caused no injuries but which leveled several thousand square kilometers of forest in a very sparsely populated part of Siberia, Russia.
The 2018 final book of physicist Stephen Hawking, Brief Answers to the Big Questions, considers a large asteroid collision the biggest threat to our planet.
Thanks largely to Spaceguard cataloging initiated by a 2005 mandate of the United States Congress to NASA,[21] the inventory of the approximately one thousand Near Earth Objects with diameters above 1 kilometer was for instance 97% complete in 2017.
[23] This preparation time could be much reduced by pre-planning a ready to launch mission, but the post-launch years needed to first meet the asteroid and then to slowly deflect it by at least the diameter of the Earth would be extremely hard to compress.
The Last Alert part of the ATLAS name acknowledges that the system will find smaller asteroids years too late for potential deflection but would provide the days or weeks of warning needed 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".
[24] Most of the more than 1 billion rubles (approximately $33M USD at the time) damage[25] and of the 1500 injuries[26] caused by the 17-m Chelyabinsk meteor impact in 2013 were from window glass broken by its shock wave.
Replacement of the initially substandard Schmidt corrector plates of both telescopes in June 2017 brought their image quality closer to its nominal 2 pixels (3.8") width and consequently improved their sensitivity by one magnitude.
[2][30][31] This geographical expansion of ATLAS provides visibility of the far Southern sky, more continuous coverage, better resilience to bad weather, and additional information on the asteroid orbit from the parallax effect.
[36] The full ATLAS concept consists of eight 50-centimeter diameter f/2 Wright-Schmidt telescopes, spread over the globe for full-night-sky and 24h/24h coverage, and each fitted with a 110 Megapixel CCD array camera.
The current system consists of four such telescopes: ATLAS1 and ATLAS2 operate 160 km apart on the Haleakala and Mauna Loa volcanoes in the Hawaiian Islands, ATLAS3 is at the South African Astronomical Observatory and ATLAS4 is in Chile.