A test to determine if asteroid defense systems could spot a potentially dangerous near-Earth asteroid on its closest approach has succeeded in ‘rediscovering’ the infamous asteroid 99942 Apophis, which will make a close encounter with our planet in 2029 .
For that asteroid defense exercise, all previous data on Apophis was made inaccessible. This meant that astronomers had to start from scratch during the close approach to the asteroidwhich began in December 2020 and peaked in March 2021. Apophis slip through the net, or could our sky survey network find it?
Numerous asteroid hunting surveys, which regularly scan the skies for potentially dangerous areas asteroidsparticipated in the project, which included more than 100 scientists from 18 countries.
Related: Planetary defense experts use the infamous asteroid Apophis to practice spotting dangerous space rocks
Apophis caused a stir when it was discovered in 2004. At that time, the asteroid’s orbit was not known enough to rule out an impact with Earth in 2029 or 2036. The B612 Foundation, a non-profit organization that supports solar system mapping and navigation research and technologies, has made public the potential danger posed by Apophis, but refined calculations of its orbit have from ruled out the possibility of an impact anytime soon.
Now astronomers have been tasked with doing it again to prove their ability to quickly identify and then assess the danger posed by any future discovery of a potentially dangerous asteroid.
The project “stress tested the entire planetary defense response chain, from initial detection, to orbit determination, to measuring the physical characteristics of the asteroid and even determining if and where it could hit Earth,” Vishnu Reddy, an associate professor at the University of Arizona. Lunar and Planetary Laboratory which carried out the campaign, said in a Statement from NASA.
During the test, Apophis was first spotted by the Catalina Sky Survey in Arizona, with later detections from the Asteroid Terrestrial-impact Last Alert System (ATLAS) – which has observatories in Chile, Hawaii and Africa South – and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii. Perhaps the most important measurements came from NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft, which used its thermal vision to accurately measure the size and shape of Apophis. He identified Apophis as an elongated object with a diameter of 886 to 1,345 feet (270 to 410 meters).
Based on the NEOWISE measurements, NASA scientists Ames Research Center in California obtained a better estimate of the energy that would be released if Apophis were to collide with Earth. They calculated that an impact would carry around 8.5 x 10^19 joules of energy, which is equivalent to 20 million kilotons of TNT and 10,000 times more powerful than the Chelyabinsk Meteor airburst over Russia in 2013. Damage from Apophis would be devastating, but only on a regional scale; it is not massive enough to cause the global extinction of human life.
On December 23, 2020, the International Astronomical Union’s Minor Planets Center, which is the collection agency for all asteroid and comet observations, had enough data to announce the rediscovery of Apophis as new asteroid, but not enough data to rule out an impact.
“Even if we knew that in reality Apophis would not have impacted Earth in 2029 from square one…there were large uncertainties in the object’s orbit that theoretically enabled an impact that year,” said Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory. , said in the statement.
Farnocchia led efforts to calculate Apophis’ orbit, which were boosted by the Goldstone Solar System radar in California in March 2021. ground radar produces images of Apophis and measures its speed and distance, giving a more accurate calculation of the asteroid’s orbit. This information was eventually enough to rule out a collision in 2029 or at least for the next 100 years.
“To see the planetary defense community come together during Apophis’ final close approach was impressive,” said Michael Kelley, program scientist in NASA’s Planetary Defense Coordination Office, in the release. “Even during a pandemic, when many exercise participants were forced to work remotely, we were able to detect, track and learn about potential danger with great efficiency. The exercise was a resounding success. “
from NASA The OSIRIS-REx mission will visit Apophis during its close approach to Earth in 2029. Meanwhile, a successor to NEOWISE, the NEO Surveyorwill be launched in the middle of the decade.
Two articles describing the results of the project have been published on May 31 in The Journal of Planetary Science.
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