Asteroid Bennu, aka object 101955, is a real threat to our planet. Scientists from NASA were convinced of this by analyzing the data collected by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) spacecraft, which was in close proximity to the asteroid, landed on it and is now carrying soil samples to Earth. The “package” with alien substance is expected in September 2023.
The measurements, which were carried out during the visit to Benn, made it possible to clarify the orbit of the asteroid and once again estimate the chances of its collision with our planet. Unfortunately, they are. What the researchers of a large group (18 people) reported in the journal Icarus in a scientific article entitled “Ephemeris and hazard assessment for near-Earth asteroid (101955) Bennu based on OSIRIS-REx data”.
Previous calculations, as it turned out, were very approximate – scientists did not fully understand how strong the influence of the so-called Yarkovsky effect, which can change the trajectory of an asteroid, is.
The essence of the effect is in the thermal effect of the Sun on the surface of at least a slightly rotating asteroid. The surface heats up, falling under the scorching rays, and cools, hiding from them – turning the other side to the Sun. At the same time, the asteroid emits photons – the cold side is smaller than the heated one. The result is an impulse – reactive force. The power is tiny – some grams. But acting constantly and for a long time, it is able to pull the asteroid to the side. For example, move it to the Earth or, conversely, move it away.
Bennu spins. The reactive force arises – really negligible, as NASA was convinced, in a few grams. But it is there. Pushes the asteroid towards the Earth.
From the revised calculations it follows: the strike, which was previously expected on September 25, 2135, is canceled. Scientists guarantee that the asteroid will fly by, albeit very close by cosmic standards – at a distance approximately equal to half the distance from the Earth to the Moon.
Refining the parameters of the asteroid's orbit, NASA took into account all possible “force” interference in its movement – the influence on Bennu of the gravity of the Sun, Lyna, neighboring planets, 300 other asteroids and even the shock that the asteroid experienced at the moment when OSIRIS-REx touched it taking soil samples. A catastrophe is out of the question. But the next dangerous rapprochement, which is expected on September 24, 2182, threatens with serious troubles.
The chances of a collision that could occur in 61 years are estimated by NASA as 1 in 2700. Or 0.037 percent. That is, they do not give a full guarantee that we will miss each other. Although they emphasize with optimism: the probability of avoiding a catastrophe is more than 99.9 percent. Which is much more than the likelihood of not avoiding it.
Uncertainty in distant forecasts is introduced by Bennu's previous flyby near the Earth – in 2135. It is not yet possible to accurately assess the strength of its attraction. It is clear that the Earth will pull him a little to itself. But how much? It will be revealed on September 26, 2135. And it will give an opportunity to continue refinements.
So far, one thing is more or less clear: Bennu will not go anywhere from the Earth – from time to time he will approach a dangerous distance and strive to crash. The chances that a disaster will still happen before 2300 are estimated by NASA as 1 in 1750 – 0.057 percent. Not zero again.
Bennu's diameter is about 500 meters. What will happen if he does collide with the Earth? There is no need to fear the end of the world. The lump is too small to become a serious threat to life in general. But the asteroid is capable of causing severe damage to humanity. If, of course, it falls somewhere in a densely populated area.
By the way, British scientist Nick Bailey from the University of Southampton, using the data collected at NASA on the orbits of near-Earth bodies with a diameter of several hundred meters – like Bennu and the like.
For the sake of scientific interest, Nick compiled a kind of “flawed rating” – identified the top ten most vulnerable countries, destruction and casualties, which will be terrifying. Maybe even such that these countries will not recover at all.
According to simulations, China, Indonesia, India, Japan and the United States will be the worst. This is followed by the Philippines, Italy, Great Britain, Brazil and Nigeria.
Russia, fortunately, is not included in the “killer top ten”. Obviously, due to their vastness, backwardness and sparsely populated individual regions. In some places, in terms of development, nothing has changed since the fall of the Tunguska meteorite in 1908. Fell so what? Didn't even destroy anything. Didn't kill anyone. Although it has become a global event.
What if the blow hits the water? The answers are also in our material What will happen if a kilometer-long asteroid falls into the ocean
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Experts from the National Space Agency of the People's Republic of China (China National Space Science Center) recently unveiled plans to save humanity from the death of the asteroid Bennu, the most dangerous space object known so far.
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