Asteroid: we know more about Apophis which will graze the Earth in 2029

Apophis. It was discovered in June 2004. A asteroid some 350 meters and about 27 million tons. And for a few weeks, the scientific community had been worried about a possible impact with our Earth in April 2029. Just a few weeks. Because from the month of December 2004, archive data showed that the collision was very unlikely. And new data collected since – in particular on the occasion of the passage of Apophis only 17 million kilometers from our Earth, on March 6, 2021 – have further removed the risk. I’asteroid orbit is now sufficiently defined to exclude, with certainty, any impact for at least a hundred years.

“Collision is not the only possibility in approach events like this”says Gabriel Berderes-Motta, researcher at the University of Madrid (Spain), in a communicated. “The gravitational interaction between a planet and a body like Apophis can alter the shape of the body, shatter it into pieces, disintegrate any loose rocks on the surface of the asteroid, or even eliminate other bodies orbiting the planet. asteroid (rocks, satellites or rings). »

With his team, he analyzed the physical characteristics of Apophis. Its shape. As well as its gravitational field. And the factors that could influence its trajectory and slope angle. The radiation pressure, for example. Or the disturbances due to its passages to proximity to earth.

Apophis will not come out unscathed

The researchers carried out a series of numerical simulations to try to understand precisely how the objects – particles, essentially – in orbit around Apophis could be affected by a rapprochement with our Planet. In a first case, taking into account only gravitational disturbances. In a second case, including the disturbances due to the pressure of the solar radiation. All in 24-hour periods over a duration 30 years old. With varying density of orbiting objects.

The conclusion is that the angle ofimpact of the asteroid appears greater for a low density of objects in orbit (4°) than for a high density (2°). On the other hand, when the density of the particles decreases and the pressure of the solar radiation increases, these objects in orbit struggle to remain intact. And finally, in a scenario where Apophis had a low density, about 90% of the loose rocks on its surface would be stripped away as it approached Earth. The researchers also show that Apophis’ approach could have minimal impact on the tides and produce some landslides on the surface of the asteroid.

The astronomers now hope to take advantage of the passage of Apophis near our planet in 2029 to refine their model. And better predict the effects of asteroid approach events in general in the future.

The 350m asteroid Apophis poses no threat for the next 100 years

New observations of the asteroid Apophis rule out any risk of impact for at least a century. After 17 years of observations and analyzes of orbit, the asteroid is therefore removed from the list of potential impactors.

Article ofAdrien Coffinet published on 05/04/2021

The asteroid Apophis, which measures around 350 meters in diameter, has regularly made headlines since its discovery in 2004, due to the low but not zero risks it had ofcollide with the Earth in the following decades.

Shortly after its detection, astronomers predicted two impact hazards, in 2029 and in 2036. Additional observations of the object NEO fortunately excluded them. Until recently, however, there remained a small risk of an impact in 2068.

Impact excluded thanks to radar measurements

New radar observations of Apophis have been carried out at the beginning of March speak Goldstone Deep Space Communications Complex from NASA, California, and the Green Bank Observatory, West Virginia. They provided enough data on the asteroid’s orbit to finally rule out, with certainty, any impact with Earth for at least 100 years.

These last observations were possible because the asteroid passed in the vicinity of the Earth on March 6, at a distance of approximately 17 million kilometers (44 times the Earth-Moon distance). Although the asteroid was still relatively distant, astronomers were able to accurately measure its distance and refine its orbit ahead of its next very close pass in 2029.

No passage through the “keyhole”

The position and orbit of the planets are known very precisely, but for smaller objects like asteroids, the uncertainty is often greater, especially when there are still few observations of them. To complicate matters, when asteroids pass close to massive objects like planets, they are deflected and the uncertainty about their path is amplified.

Prior to the latest radar measurements of Apophis, its orbit was known precisely enough to predict a series of safe close passes over the next several decades. The next and closest will be on Friday, April 13, 2029, when Apophis will pass 38,000 kilometers from the center of the Earth (32,000 kilometers from its surface) and be visible to theeye naked. The asteroid will then be ten times closer than the Mooncloser than geostationary satellites (at an altitude of 36,000 kilometers).

Davide Farnocchia, from Center for Near-Earth Object Studies (CNEOS) of NASA, explains that, ” thanks to recent optical and radar observations, the uncertainty in Apophis’ orbit has fallen from hundreds of kilometers to just a few kilometers when projected to 2029 “. These radar observations have reduced the uncertainty in Apophis’ trajectory to such an extent that any risk of impact in 2068 or long after has been ruled out.

As a result, Apophis has been removed from the ESA list of at-risk objects and of NASA’s.

” The discovery of Apophis and the first work done to track and understand its orbit took place when today’s planetary defense activities were still in their infancy. », explains Juan Luis Cano, from Near-Earth Object Coordination Center of the’ESA.

” The fact that this happened at such an early period in the discipline was a strong motivation to improve our abilities to accurately predict the movement of these interesting and potentially dangerous objects. With today’s removal of Apophis from the risk list, we close a very instructive chapter in the history of planetary defense. »

The large asteroid Apophis, which will graze Earth in 2029, has its trajectory modified

Article of Xavier Demeersmannpublished on October 31, 2020

Everyone has heard, or almost, of Apophis, an asteroid as big as the Eiffel Tower which will graze the Earth in 2029. Without risk of collisions, as shown by the calculations of astronomers. But recent observations prompt researchers to reassess the risks for his 2068 visit.

Since astronomers discovered in 2004 that Apophis — (99942) Apophis — is a potentially dangerous asteroid that is expected to very close to Earth in 2029, 2036, 2068, 2085, 2088 according to their calculations, the celestial body about 340 meters in diameter became famous all over the world. For its passage some 31,860 kilometers above our heads, on Friday April 13, 2029 (the date is undoubtedly not unrelated to its fame!) — we will be able to see the sky crossing with the naked eye –, the researchers certify that there is almost no risk of impact with the Earth. So much the better because if it rushed straight at us, it would cause significant damage on a regional scale. But, once again, the NASA experts do not fear a collision, nor in 2029neither in 2036 nor in 2068.

Although… for this last date, we will have to review the predictions.

illustration of the asteroid Apophis. © ESA

Apophis “moves away from a purely gravitational orbit”

During the Division for Planetary Sciences meeting of the AAS (American Astronomical Society) which has just been held virtually with the research community, Davide Farnocchia, from JPL of NASA, presented its latest calculations of the trajectory ofApophis, which take into account the recent discovery of a slight Yarkovsky acceleration effect observed by colleagues at the Japanese Subaru Observatory, Hawaii. This effect related to thermal radiation is very weak and almost imperceptible, but still enough to force scientists to review their copies.

“The new sightings […] show that the asteroid is drifting away from a purely gravitational orbit by about 170 meters per year, which is enough to keep the 2068 impact scenario likely” said Dave Tholen, of the IfA (Institute for Astronomy) at the University of Hawaii, who conducted the observations.

There is no point in panicking, however, because the calculations must be reassessed in the light of future observations of the asteroid’s behavior. Astronomers say we should know if Apophis will or will not be on a collision course with our world long before its 2068 visit. To be continued.