Asteroid Bennu: The probability of impact is greater than expected

When NASA sent its Osiris-Rex probe to the asteroid Bennu on a multi-year mission in 2016, it did so for good reason: Observations and calculations of the segment’s trajectory showed that it will cross Earth’s orbit over and over again and may cross us in about 150 years, very close.

The cluster, which has an average diameter of about 500 meters and a mass of more than 60 million tons, is one of the so-called near-Earth asteroids.

In order to counteract the collision risk, NASA mapped Bennu and collected many data: previously available researchers led by David Farnocchia of NASA’s Jet Propulsion Laboratory evaluated and calculated the probability of an impact more accurately than before. Accordingly, the danger lies in Trade magazine “Ikarus” A study published at 1:1750 that Bennu could collide with Earth by the year 2300. Previous calculations were somewhat more reassuring and reached a probability of 1:2700 for an impact of up to 2200.

The determining factor in the risk of impact is the impact of the Earth on Bennu’s flyby in the year 2135. Then it will be closer to us than the Moon and about half the distance from our satellite, which is about 380 thousand km away. As for the trajectory of future trails, the deciding factor is how close Bennu is to Earth at this moment—and whether Earth’s more massive gravity pulls on and deflects the relatively small piece.

To do this, Bennu will have to pass through certain precise regions near our planet, and astronomers are talking about the so-called gravitational holes. The Bennu 2135 avoids 24 out of 26 keyholes greater than 1 kilometer. However, Bennu could hit Earth sometime later with a probability of 1:1750 or 0.057 percent because its trajectory is skewed accordingly. The researchers even calculated the potential impact history. It’s September 24, 2182. The probability of this event occurring is 1 in 2700 (0.037 percent).

However, based on the new study, there is no need to panic. Speaks astronomer Farnocchia opposite the New York Times. Without much change. He was no more anxious than before, as it was said that the probability of the impact was still very low. However, researchers cannot rule out an impact by 2300. On the Palermo scale, which shows how high the risk of an impact is, Bennu is at the top, along with the asteroid (29075) 1950 DA, which also crosses the orbit of Mars.

To Bennu, who was named after the ancient Egyptian god of the dead and in 1999 in the meantime The collapsed Arecibo telescope It was discovered in Puerto Rico, and not all data are available for a better collision estimate. For example, the “Osiris Rex” is currently still taking soil samples and probably won’t reach Earth until 2023. The Bennu surface quality results are very relevant. The so-called Jarkowsky effect, named after a Russian engineer, plays a role in changes in the tracks.

The different degrees of surface temperature rise in the asteroid caused by the sun affect the deflection of the asteroid’s motion. Sunlight is first absorbed by an asteroid or meteor and then released again in the form of infrared radiation with a slight delay. But since the rotation of the body heats its sides to different degrees, there is a difference in radiation that Benno can easily deflect inward or outward. How strong the effect is depends, for example, on the reflectivity and therefore on the surface properties of a celestial body. That is why one of the goals of “Osiris Rex” is to determine as accurately as possible the influence of Benno Jarkowski. This effect has an effect on many asteroid tracks and may direct large chunks of the asteroid belt into the Solar System more frequently than in collisions with other masses.

It is very likely that the path of Benos will be more accurately modeled in the future. According to the researchers’ estimates, these other remnants from the early stage of our solar system were not detected anyway – or that they actually fly over Earth a few thousand kilometers away. The asteroid “2020 QG”, the size of a small car, passed the southern Indian Ocean in August 2020 at an altitude of nearly 3,000 km.

Collisions also sometimes occur: a few years ago, the explosion of a piece of 20 meters high over the Russian city of Chelyabinsk caused devastation. Hundreds of people were injured by falling meteors from the debris of an estimated 16,000 tons of orbs, mostly from broken windows. The researchers estimate that asteroids over 500 meters above Earth cause damage over the region when they impact. The size of the pit in such events is usually ten to 20 times the size of the body. So Bennu will not threaten the existence of Earth, but it can cause serious damage and take many victims.

In any case, experts have long been working on techniques to keep dangerous near-Earth asteroids away from Earth. China, for example, calculated that 23 Long March 5 missiles were used. Benno can divert from Earth’s path. Until now, most experts assumed that using a so-called kinetic impactor, which shoots the boulder off the track like a billiard ball, is Earth’s only chance in an emergency.