Apophis Asteroid Investigation - JPL - NASA

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• published: 18 Aug 2012
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99942 Apophis (play /əˈpɒfɪs/, previously known by its provisional designation 2004 MN4) is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a small probability (up to 2.7%) that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole, a precise region in space no more than about a half-mile wide,that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis will pass through the keyhole was determined to be very small. Apophis broke the record for the highest level on the Torino Scale, being, for only a short time, a level 4, before it was lowered.Its diameter is approximately 270 meters (885 ft). As of October 7, 2009, the probability of an April 13, 2036 impact is considered to be 1 in 250,000. Of objects not recently observed, there are 7 asteroids with a more notable Palermo Technical Impact Hazard Scale than Apophis. Based upon the observed brightness, Apophis' diameter was initially estimated at 450 metres (1,480 ft); a more refined estimate based on spectroscopic observations at NASA's Infrared Telescope Facility in Hawaii by Binzel, Rivkin, Bus, and Tokunaga (2005) is 350 metres (1,150 ft). Nasa's impact risk page currently lists the diameter at 0.270km (270m) or roughly the size of two football fields. During the 2029 approach, Apophis' brightness will peak at magnitude 3.4 with a maximum angular speed of 42° per hour. The maximum apparent angular diameter will be ~2 arcseconds, so that it will be barely resolved by telescopes not equipped with adaptive optics. After the Minor Planet Center confirmed the June discovery of Apophis, an April 13, 2029 close approach was flagged by NASA's automatic Sentry system and NEODyS, a similar automatic program run by the University of Pisa and the University of Valladolid. On that date, it will become as bright as magnitude 3.4[11] (visible to the naked eye from rural as well as darker suburban areas, visible with binoculars from most locations[14]). This close approach will be visible from Europe, Africa, and western Asia. As a result of its close passage, it will move from the Aten to the Apollo class. After Sentry and NEODyS announced the possible impact, additional observations decreased the uncertainty in Apophis' trajectory. As they did, the probability of an impact event temporarily climbed, peaking at 2.7% (1 in 37). Combined with its size, this caused Apophis to be assessed at level 4 on the Torino Scale and 1.10 on the Palermo Technical Impact Hazard Scale, scales scientists use to represent the danger of an asteroid hitting Earth. These are the highest values for which any object has been rated on either scale. It has since been downgraded to level 0 on the Torino Scale for both the 2029 and 2036 passes.With a cumulative Palermo Scale rating of -2.9, the risk of impact from Apophis is less than the background hazard level. On Friday, April 13, 2029, Apophis will pass Earth within the orbits of geosynchronous communication satellites.[15] It will return for another close Earth approach in 2036. The 2029 pass will actually be much closer than the first predictions, but the uncertainty is such that an impact is ruled out. Similarly, the pass on April 13, 2036, carries little risk of an impact. The close approach in 2029 will substantially alter the object's orbit, making predictions uncertain without more data. "If we get radar ranging in 2013 [the next good opportunity], we should be able to predict the location of 2004 MN4 out to at least 2070." said Jon Giorgini of JPL.[16] Apophis will pass within 0.0966 AU (14,450,000 km; 8,980,000 mi) of the Earth in 2013, allowing astronomers to refine the trajectory for future close passes. Just after the close approach on 9 January 2013, the asteroid should peak at about apparent magnitude 15.7.On January 31, 2011, astronomers took the first new images of Apophis in more than 3 years. In July 2005, former Apollo astronaut Rusty Schweickart, as chairman of the B612 Foundation, formally asked NASA to investigate the possibility that the asteroid's post-2029 orbit could be in orbital resonance with Earth, which would increase the probability of future impacts. Schweickart asked for an investigation of the necessity of placing a transponder on the asteroid for more accurate tracking of how its orbit is affected by the Yarkovsky effect.

Apophis Asteroid Investigation - JPL - NASA

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• published: 18 Aug 2012
• views: 8252

99942 Apophis (play /əˈpɒfɪs/, previously known by its provisional designation 2004 MN4) is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a small probability (up to 2.7%) that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole, a precise region in space no more than about a half-mile wide,that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis will pass through the keyhole was determined to be very small. Apophis broke the record for the highest level on the Torino Scale, being, for only a short time, a level 4, before it was lowered.Its diameter is approximately 270 meters (885 ft). As of October 7, 2009, the probability of an April 13, 2036 impact is considered to be 1 in 250,000. Of objects not recently observed, there are 7 asteroids with a more notable Palermo Technical Impact Hazard Scale than Apophis. Based upon the observed brightness, Apophis' diameter was initially estimated at 450 metres (1,480 ft); a more refined estimate based on spectroscopic observations at NASA's Infrared Telescope Facility in Hawaii by Binzel, Rivkin, Bus, and Tokunaga (2005) is 350 metres (1,150 ft). Nasa's impact risk page currently lists the diameter at 0.270km (270m) or roughly the size of two football fields. During the 2029 approach, Apophis' brightness will peak at magnitude 3.4 with a maximum angular speed of 42° per hour. The maximum apparent angular diameter will be ~2 arcseconds, so that it will be barely resolved by telescopes not equipped with adaptive optics. After the Minor Planet Center confirmed the June discovery of Apophis, an April 13, 2029 close approach was flagged by NASA's automatic Sentry system and NEODyS, a similar automatic program run by the University of Pisa and the University of Valladolid. On that date, it will become as bright as magnitude 3.4[11] (visible to the naked eye from rural as well as darker suburban areas, visible with binoculars from most locations[14]). This close approach will be visible from Europe, Africa, and western Asia. As a result of its close passage, it will move from the Aten to the Apollo class. After Sentry and NEODyS announced the possible impact, additional observations decreased the uncertainty in Apophis' trajectory. As they did, the probability of an impact event temporarily climbed, peaking at 2.7% (1 in 37). Combined with its size, this caused Apophis to be assessed at level 4 on the Torino Scale and 1.10 on the Palermo Technical Impact Hazard Scale, scales scientists use to represent the danger of an asteroid hitting Earth. These are the highest values for which any object has been rated on either scale. It has since been downgraded to level 0 on the Torino Scale for both the 2029 and 2036 passes.With a cumulative Palermo Scale rating of -2.9, the risk of impact from Apophis is less than the background hazard level. On Friday, April 13, 2029, Apophis will pass Earth within the orbits of geosynchronous communication satellites.[15] It will return for another close Earth approach in 2036. The 2029 pass will actually be much closer than the first predictions, but the uncertainty is such that an impact is ruled out. Similarly, the pass on April 13, 2036, carries little risk of an impact. The close approach in 2029 will substantially alter the object's orbit, making predictions uncertain without more data. "If we get radar ranging in 2013 [the next good opportunity], we should be able to predict the location of 2004 MN4 out to at least 2070." said Jon Giorgini of JPL.[16] Apophis will pass within 0.0966 AU (14,450,000 km; 8,980,000 mi) of the Earth in 2013, allowing astronomers to refine the trajectory for future close passes. Just after the close approach on 9 January 2013, the asteroid should peak at about apparent magnitude 15.7.On January 31, 2011, astronomers took the first new images of Apophis in more than 3 years. In July 2005, former Apollo astronaut Rusty Schweickart, as chairman of the B612 Foundation, formally asked NASA to investigate the possibility that the asteroid's post-2029 orbit could be in orbital resonance with Earth, which would increase the probability of future impacts. Schweickart asked for an investigation of the necessity of placing a transponder on the asteroid for more accurate tracking of how its orbit is affected by the Yarkovsky effect.