On April 13, 2029, an asteroid about 340 meters in diameter, Apophis, will pass about 32,000 kilometers from the Earth’s surface; If we take into account that the distance that separates us from the Moon is 384,000, the risk is obvious. Still, NASA has ruled out an Apophis collision with Earth for at least the next hundred years. But the distance will be so small in astronomical terms that our planet will have an appreciable physical influence on the asteroid. And now a new study, published in The Planetary Science Journalraises a much stranger possibility: that the main problem in studying that encounter comes not from Apophis, but from something we ourselves have left around the Earth.
To understand how close it will be, a comparison is enough. The Moon is, on average, about 384,000 kilometers from us. Apophis will be approximately twelve times closer. And it will do so even below the geostationary orbit, located about 36,000 kilometers above the Earth’s equator. That’s a huge distance for us, but extraordinarily small for an object traveling through the solar system. And precisely that proximity makes Apophis a natural laboratory.
When the asteroid approaches Earth, Our planet’s gravity will not simply change its trajectory slightly. Tidal forces could modify its rotation and cause movements or landslides on its surface. For the first time we will be able to observe in detail what happens when an asteroid of this size comes so close to a planet. Several missions want to take advantage of the opportunity. Among them is OSIRIS-APEXthe NASA spacecraft that will continue its journey to Apophis after completing its original mission with the asteroid Bennu. He The objective will be to study how the object has changed after its encounter with Earth.
And there appears an unexpected difficulty: what would happen if something hit Apophis before we could study it? The authors of the study, led by Giulia Schettino, have analyzed the possibility that the asteroid encounters one of the numerous artificial objects that remain in orbit around our planet. The probability of a collision is extremely small, but Apophis will pass through a region of space where there are also decommissioned satellites and fragments of space debris.
“We argue that, while the probability of collision is likely extremely low, the possibility of interaction cannot be completely ruled out,” the study notes. A possible impact with abandoned debris could affect the rotational dynamics of the asteroid and jeopardize the success of any planned experiments on its surface, suggesting that a thorough characterization of the projected 2029 population is essential.”
A collision could slightly modify the rotation of Apophis, produce a crater, or lift material from its surface. And any of those changes could later be confused with effects caused by the Earth itself.
Schettino’s team wants to observe precisely how the asteroid responds to our planet’s gravitational and tidal forces. If Apophis arrives at the meeting already altered by a collision with an artificial fragment, separating one cause from the other would be much more complicated. One of the aforementioned phrases sums it up perfectly: “The possibility of an interaction cannot be completely ruled out”. That is why they consider it necessary to better characterize the population of objects that will occupy that region of space in 2029.
The paradox is fascinating. We can calculate with enormous precision where Apophis will be in three years and we know that it will not collide with Earth. But we know much less about all the small objects that can be found around our planet, objects that we have left behind. And this is a first from space. But it is certainly not the last: that is what worries scientists.