99942 Apophis (Apophis is the Greek name for the Egyptian god Apep, the Destroyer) is an example of a near-Earth asteroid estimated to be about 370 meters in size and discovered on June 19, 2004 by Roy Tucker, David Tholen, and Fabrizio. . Bernardi attended.University of Hawaii Asteroid Survey (UHAS), an observing expedition funded by NASA and using an observatory located in Kit Peak, Arizona.
Originally cataloged as 2004 MN4, the asteroid was later renamed Apophis (it appears that AstronomersAstronomers The discovery was originally a fan of the series Stargate). Early estimates of its orbital parameters have alarmed astronomers, as an impact with Earth is possible on April 13, 2029 (preliminary calculations showed a 2.7% chance that the 27-million-ton asteroid would hit our planet).
An explosion of tens of thousands of Hiroshima bombs on Earth in 2029?
However, some guesses about its composition (it was once thought to correspond to meteorites called siderites, so metallic and dense, but today we think it is more closely related to rock chondrites) and suggests its angle of impact with the Earth. It will then detonate tens of thousands of times the same amount as the bomb that wiped the city of Hiroshima off the map in 1945 (99942) Apophis will enter.EnvironmentEnvironment With 1,200 megatonsKinetic energyKinetic energyor the resulting impact energies Meteor CraterMeteor Crater or the Tunguska event is estimated to be between 3 and 10 megatons). Its falling into the sea would hardly cause much joy as it would produce one. TsunamiTsunami with the The wavesThe waves 170 meters high running at a speed of 100 km/h!
Asteroids may be dangerous to life on Earth, but they also provide clues about the early days of the solar system. In the video series Asteroid Crash CourseDenton Abel, curator of the museum’s Division of Physical Sciences, explains how asteroids form and the varying degrees of destruction they cause when they hit Earth. To get a fairly accurate French translation, click on the white rectangle at the bottom right. Then the English subtitles should appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Auto-Translate”. Select “French”. The series was produced by the American Museum of Natural History in New York in collaboration with the Denver Museum of Nature and Science. GOTO, Inc., Tokyo, Japan; and Shanghai Science and Technology Museum, China. © American Museum of Natural History, New York, NY
Fortunately, during the last days of December 2004, A PhotographyPhotography Taken a few months before June, 99942 Apophis (now its official name) was found in the archives, giving a more accurate estimate of the asteroid’s speed. It was already clear in 2004 that the effect in 2029 was actually very small. As the years went by, with new data accumulating, the risk continued to decrease. The researchers had some concerns for 2036 and beyond 2068, but even here risk assessments have only reduced the likelihood of an encounter. It is also now estimated that there is only a one in 110,000 chance of 99942 Apophis hitting Earth between 2060 and 2105.orbitorbit In Puerto Rico, in January and August 2005, and again in May 2006, near-ground observations could actually be improved thanks to the Arcebo radar.
99942 Apophis will be visible to the naked eye in April 2029
So NASA has had no concern for 2029 since 2004, and much less for 2036 since at least 2013. On the other hand, within four years, amateur astronomers and even the general public should celebrate as 99942 Apophis is expected to pass by about 31,000 kilometers. From Earth, i.e. geostationary within the asteroid’s Clark orbit, given its size, it should look atthe eyethe eye Bare on topSouthern HemisphereSouthern Hemisphere. Flying over land from the east coast to the west coast of Australia, it will then cross the Indian Ocean and then the eastern United States.
In 2010, Cnes was already vouching for Apophis. © Cnes, French Space Agency
Astronomers are already thinking about what they can do next. Thus, for Marina Brozovic, an expert on radar observations in astronomy Jet Propulsion LaboratoryJet Propulsion Laboratory From NASA in Pasadena, California: “A close encounter between Earth and Apophis in 2029 will be an incredible opportunity for science. We will observe the asteroid with it. BinocularsBinoculars In the visible, but also with radars. With radar observations, we can see surface details from only a few meters away. »
In 2013, CNES was also considering a mission to Apophis. Eventually, NASA did it by extending the mission.Osiris-RexOsiris-Rex Having already detached itself with samples from the surface of asteroid Bennu to divert it to Apophis, the Osiris mission became.Apex put Apophis Explorer. L’ESAESAFor his part, Ramses prepares for the mission.. We can learn many things that will be valuable in determining the best strategy to adopt to remove a truly dangerous asteroid, for example about the internal structure of 99942 Apophis.
Looking forward to 2029, the story of scientific articles about Apophis continues, as clearly shown in an article available online. arXiv. A team of researchers suggests, based on Digital simulationDigital simulation But ComputerComputerOnly landslides and especially EarthquakesEarthquakes expected to occur on asteroids due to Sea forcesSea forces What will be the field of GravityGravity of Earth, while passing close to a smaller celestial body.
The Mystery of the Missing Space Erosion
The AstronomersAstronomers It was brought to this conclusion by trying to solve a problem with asteroids. We know, especially by studying the main asteroid belt between Mars and JupiterJupiterthat their surfaces are constantly bombarded with dust and small rocks from collisions between asteroids. Effect of particles from Solar windSolar windso that we know that there is what we can call local erosion.
The result is that the surface appearance of these asteroids in the belt is not the same as that of meteorites that fall to Earth, which are fresh and uneroded, having been in space for a very short time. The time between the dismemberment of the parents’ bodies after the collision and their ejection due to their arrival on Earth.
However, strangely, when near-Earth asteroids pass close to Earth, their surfaces – again – show no signs of space erosion.
The answer given by researchers today is that Earth’s tidal forces, moving and kneading an asteroid near Earth, “resurface” its skin, causing earthquakes and landslides. Set him free. from local erosion effects. To be precise, landslides there are mainly caused by the change in the axis of rotation and the rotation of the asteroid due to the gravity of the Earth. These changes will lead to instability of surface rocks. But, unlike earthquakes, these changes will occur gradually.
We will probably have observations confirming this scenario, which will therefore solve the decades-old puzzle with data from the Osiris mission.ApexApex which will study the chemical composition and map the surface of 99942 Apophis for 18 months.
