Since scientists monitored the asteroids around us, no object had so much risk of overthrowing on earth. The recently discovered object of 2024 YR4 is the topic of all attention. How does it look? How do you avoid a collision? What would the consequences be? The answers from Olivier Sangy, head of Space News at the Cité de l’Eospace de Toulouse.
What exactly do we know on 2024 YR4? How big is its size, its trajectory?
Its size is between 40 and 100 meters with a probable estimate of around 55 meters, according to NASA. We have a good approach to his trajectory, but not yet absolute certainty: we know that it is developed between 0.8 and 4 units astronomic Sun (an astronomical unit that represents 150 million kilometers, the earth’s removal). And we know that he hits the terrestrial orbit. We don’t yet know as far as his composition is concerned. Asteroids can be rocky or metallic. Metalics are more worrying because they are better resistant to entry into the atmosphere and release much moreenergy Effects.
How did we discover it?
It was discovered by Atlas, a system that has potentially dangerous asteroids. In addition, it is not the only existing system. There is a real international cooperation in monitoring asteroids, with NASA and ESA (European Space Agency) keep an eye on. Atlas has automated telescopes in Hawaii, Chile and South Africa. It was that of Chile who found for 2024 years.
So we manage to recognize all the asteroids that could threaten us?
Today we have cataloged almost all asteroids of more than one kilometer that would really be catastrophic for human civilization. Diploma ? Nobody represents a short or medium -term threat. But then we found that we had a hole in the racket: the asteroids between 10 and 100 meters in diameter. Too small to be discovered long in advance, but large enough to cause serious local damage. These “city killers”, as the Americans call them, are our main guard man.
And so in 2024 years 4 joins this category?
The problem is that our measures always have an error rate. If you project your orbit by 2032, you will receive a trajectory cone and … the earth is inside. It does not mean that he will definitely meet us, but there is this uncertainty. Today the risk is estimated at 1.2 %.
What will happen now?
The challenge is to reduce uncertainty by continuing to be observed. Problem: It is a relatively small object, and in April even the most powerful telescopes can no longer see it. If we were unable to specify your trajectory until then, we have a new chance in 2028 if it returns near us. The aim is to have a sufficiently precise projection of your orbit in order to permanently rule out a risk in 2032.
If this risk has been confirmed?
We would then enter the planetary protective phase. In contrast to earthquakes or hurricanes, asteroids are the only natural disaster that can be provided for years or even decades in advance. If necessary, a deviation mission with a probe could be taken into account, such as the darts mission, which recently managed to change the trajectory of an asteroid.
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Ship against asteroids: “We will know what to do” … The Dart mission is an overall success
If an asteroid of this size hit the earth, what should be expected?
The influence depends on its exact size and speed, but it is estimated that an object like 2024 YR4 could scratch a city like Paris and dig a crater with a kilometer in diameter. If he fell at sea, he would cause a tsunami. But I repeat: currently no certainty about an impact in 2032. The main thing is to continue surveillance and keep a cool head.