As the French expert indicates, the size of asteroid 2024 YR4 “is between 40 and 100 meters, with a probable estimate of around 55 meters, according to NASA… And we know that it crosses Earth’s orbit. As for its composition, we don’t know it yet.”
Asked whether all potentially threatening asteroids have been detected, Olivier Sanguy replied: “Today, we have catalogued almost all asteroids that are larger than a kilometre, those that would be truly catastrophic for human civilisation. Conclusion? None of them pose a threat in the short or medium term. But then we realised that we had a gap in the net: asteroids between 10 and 100 metres in diameter. Too small to be detected well in advance, but large enough to cause serious local damage. These “City Killers”, as the Americans call them, are our main point of vigilance.” As for 2024 YR4, the specialist indicates that there’s always a margin of error in the measurements that are taken. “When we project its orbit to 2032, we get a trajectory cone, and… the Earth is inside. This doesn’t mean that it will necessarily hit us, but that uncertainty exists. Today, the risk is estimated at 1.2%.” The objective today is to “to have a sufficiently precise projection of its orbit to definitively eliminate any risk in 2032”.
If the threat were indeed real, Olivier Sanguy declares that we would enter what is called the planetary protection phase. “Unlike earthquakes or hurricanes, asteroids are the only natural disaster that can be predicted years, even decades in advance. If necessary, we could consider a deflection mission with a probe.”
By hitting the Earth, 2024 YR4 “could wipe a city such as Paris off the map and dig a crater a kilometer in diameter. If it fell into the sea, it would cause a tsunami. But I repeat: for the moment, there’s no certainty about an impact in 2032”, the professor specifies.
