Apophis

RELEASE : 09-232


NASA Refines Asteroid Apophis' Path Toward Earth


PASADENA, Calif. -- Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.

The Apophis asteroid is approximately the size of two-and-a-half football fields. The new data were documented by near-Earth object scientists Steve Chesley and Paul Chodas at NASA's Jet Propulsion Laboratory in Pasadena, Calif. They will present their updated findings at a meeting of the American Astronomical Society's Division for Planetary Sciences in Puerto Rico on Oct. 8.

"Apophis has been one of those celestial bodies that has captured the public's interest since it was discovered in 2004," said Chesley. "Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a million."

A majority of the data that enabled the updated orbit of Apophis came from observations Dave Tholen and collaborators at the University of Hawaii's Institute for Astronomy in Manoa made. Tholen pored over hundreds of previously unreleased images of the night sky made with the University of Hawaii's 88-inch telescope, located near the summit of Mauna Kea.

Tholen made improved measurements of the asteroid's position in the images, enabling him to provide Chesley and Chodas with new data sets more precise than previous measures for Apophis. Measurements from the Steward Observatory's 90-inch Bok telescope on Kitt Peak in Arizona and the Arecibo Observatory on the island of Puerto Rico also were used in Chesley's calculations.

The information provided a more accurate glimpse of Apophis' orbit well into the latter part of this century. Among the findings is another close encounter by the asteroid with Earth in 2068 with chance of impact currently at approximately three-in-a-million. As with earlier orbital estimates where Earth impacts in 2029 and 2036 could not initially be ruled out due to the need for additional data, it is expected that the 2068 encounter will diminish in probability as more information about Apophis is acquired.

Initially, Apophis was thought to have a 2.7 percent chance of impacting Earth in 2029. Additional observations of the asteriod ruled out any possibility of an impact in 2029. However, the asteroid is expected to make a record-setting -- but harmless -- close approach to Earth on Friday, April 13, 2029, when it comes no closer than 18,300 miles above Earth's surface.

"The refined orbital determination further reinforces that Apophis is an asteroid we can look to as an opportunity for exciting science and not something that should be feared," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL. "The public can follow along as we continue to study Apophis and other near-Earth objects by visiting us on our AsteroidWatch Web site and by following us on the @AsteroidWatch Twitter feed."

The science of predicting asteroid orbits is based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids.

NASA detects and tracks asteroids and comets passing close to Earth using both ground and space-based telescopes. The Near Earth-Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. Cornell University operates the Arecibo Observatory under a cooperative agreement with the National Science Foundation in Arlington, Va.

MOSCOW, Dec 30, 2009 (AFP) - Russian scientists will soon meet in secret to work on a plan for saving Earth from a possible catastrophic collision with a giant asteroid in 26 years, the head of Russia's space agency said Wednesday.

"We will soon hold a closed meeting of our collegium, the science-technical council to look at what can be done" to prevent the asteroid Apophis from slamming into the planet in 2036, Anatoly Perminov told Voice of Russia radio.

"We are talking about people's lives," Perminov was quoted by news agencies as telling the radio station.

"Better to spend a few hundred million dollars to create a system for preventing a collision than to wait until it happens and hundreds of thousands of people are killed," he said.

The Apophis asteroid measures approximately 350 metres (1,150 feet) in diameter and RIA Novosti news agency said that if it were to hit Earth when it passes nearby in 2036 it would create a new desert the size of France.

Perminov said a serious plan to prevent such a catastrophe would probably be an international project involving Russian, European, US and Chinese space experts.

Interfax quoted him as saying that one option would be to build a new "space apparatus" designed solely for the purpose of diverting Apophis from a collision course with Earth safely.

"There won't be any nuclear explosions," Perminov said. "Everything will be done according to the laws of physics. We will examine all of this."

In a statement dated from October and posted on its website, the US space agency NASA said new calculations on the path of Apophis indicated "a significantly reduced likelihood of a hazardous encounter with Earth in 2036."

"Updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036, for Apophis has dropped from one-in-45,000 to about four-in-a-million," NASA said.

RIA Novosti said the asteroid was expected to pass within 30,000 kilometres (18,600 miles) of Earth in 2029 -- closer than some geo-stationary satellites -- and could shift course to hit Earth seven years years after that.

Apophis: possible collision avec la Terre le 13 avril 2036 (scientifiques russes)

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Les astronomes russes ont calculé la date éventuelle de collision entre l'astéroïde Apophis et la Terre, du reste très peu probable, a annoncé mercredi à Moscou Leonid Sokolov, professeur à la faculté de mécanique céleste de l'université de Saint-Pétersbourg.
"Le 13 avril 2029, Apophis s'approchera de la Terre à une distance d'environ 37.000 ou 38.000 kilomètres. Il peut entrer en collision avec la Terre le 13 avril 2036", a indiqué M.Sokolov.
D'autres chercheurs, entre autres les experts de l'Institut d'astronomie appliquée de l'Académie des sciences de Russie, considèrent cette collision comme peu probable.
Découvert le 19 juin 2004, l'astéroïde Apophis doit son nom au dieu des forces du chaos dans la mythologie égyptienne. Il a un diamètre de 270 m et suit une orbite proche de celle de la Terre. Pendant une période en 2004, on a pensé qu'Apophis s'écraserait sur la Terre en 2029, dégageant une énergie égale à l'explosion de 34 bombes nucléaires de Hiroshima. Plus tard les chercheurs ont écarté cette hypothèse, mais une éventuelle collision est toujours possible plus tard.
Selon l'agence spatiale américaine (NASA) citée par le professeur Sokolov, onze objets spatiaux pourraient entrer en collision avec la Terre au XXIe siècle dont quatre avant 2050.