Apophis will serve to train planetary defense system


When Apophis (officially, 99942 Apophis) is within reach of telescopes, a scenario will begin at each observatory on the planet that could save the Earth from annihilation. Your observation will be an exercise for planetary defense, but as if the asteroid had been detected now and not, in 2004.

“The goal is basically to form a coalition with scientists from around the world to try to observe this object for months,” planetary scientist Vishnu Reddy of the University of Arizona, who is coordinating the Earth’s defense project, told Space.com.

Apophis will be within reach of telescopes next Friday (5th), passing almost 16.9 million kilometers from our planet (44 times the distance to the Moon); it is on that date that the training of the International Asteroid Warning Network (IAWN) will begin, when about 40 scientists from 13 countries (those enrolled in the exercise) will pretend that they have never seen the asteroid in their life, evaluating from the zero if there are risks of hitting us.

This is the third exercise that the entity organizes. The previous training sessions were carried out with the asteroids 2012 TC4 (which is 15 meters in diameter and was visited by the NEO II mission, which collected and returned to Earth with samples) and the 1999 1999 KW4 double system.

“The goal is to get new observations as if we don’t know anything about this object and try to see how we can improve the process and increase the efficiency of the system. Anyone who deals with scientists knows what it’s like to shepherd cats: when you do it on a scale international, it’s part diplomacy, part science and part planetary defense, ”said Reddy.


The effort is aimed at refining a defense strategy that should not, of course, be based on despair. The threat exists: in 2013, an asteroid the size of a six-story building appeared without warning exploded over the city of Chelyabinsk, Russia.

Apophis, unlike asteroids that are discovered by terrestrial telescopes, was identified by the Wide-field Infrared Survey Explorer (WISE) space telescope, a NASA infrared wave receiver for mapping the cosmos. When his hydrogen supply ran out and he could no longer cool, NASA gave him another mission (hence NEOWISE): to identify as-yet-cataloged asteroids.

Since it was discovered, the Apophis has been closely monitored (mainly by the late Arecibo Radio Telescope). If most of the 25,000 asteroids near Earth are too small to cause damage, it is 300 meters wide and 300 meters high.

Pushed against the Earth

Models based on the first observations suggested an almost 3% chance that Apophis would hit Earth on April 13, 2029 (it will pass so close that it can be seen by eye when it invades the space where some satellites circulate in high orbit. the planet).

“Assuming that we know nothing about it and that we have just discovered it, there is a risk of reasonable impact. Of course, if you include the historical observations, you will know that it will move away, because we know its orbit very well, ”said Reddy.

The relief is real, but not for those who will be in the game: “Good news is not what we want, but to be able to see the effects of an impact on the ground. Then, at some point, the training will detach from reality and, in computer models, scientists will push Apophis towards Earth. ”

For the astrophysicist, the passage of the asteroid in the middle of the covid-19 pandemic may be an opportunity to test the resilience of the detection system of these bodies: “There is a reasonable amount of redundancy in planetary defense. Even if we lose a telescope, we hope that the community to remain. “


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