the 1April 3, 2029 the eyes of the world will be turned towards the sky. Not to admire a shower of shooting stars or an eclipse, but to observe the passage of Apophis, an asteroid the size of a cruise ship. This event marks a crucial moment in our understanding of asteroid risk. What was once seen as a potential threat has transformed into an unprecedented scientific opportunity. As Apophis hurtles just 32.000 km from Earth, scientists will collect valuable data that could one day save our planet from a real cosmic threat.
Apophis: from threat to opportunity
Apophis, a name derived from the Egyptian god of chaos, was discovered in 2004. At first, its calculated orbits for 2029 and 2036 placed Earth in a collision “danger zone.” However, subsequent observations and radar detections have greatly refined the orbital projections. We now know that on April 13, 2029, Apophis will miss Earth by just 32.000 kilometers. A joke, if you consider that our geostationary satellites are at greater distances: not to mention the Moon. In the image (the distances are to scale, the celestial objects obviously are not) you can get an idea.
Size and potential impact
With a diameter of about 350 meters, Apophis is comparable in size to a modern cruise ship or one of America's huge nuclear aircraft carriers. An impact on land could destroy an area the size of an entire state, while an impact at sea would trigger devastating tsunamis. For this reason, since the test bench is very serious, the European Space Agency (ESA) is planning the mission RAMSES (Rapid Apophis Mission for Space Safety) to study Apophis during its flyby. Part of the Planetary Defense Program, the mission aims to better understand the composition and behavior of the more than 1.000 “planet-killing” asteroids known to cross Earth's orbit.
Little time, a lot of motivation
The short four-year notice for the RAMSES mission is not entirely accidental. ESA presents this challenge as a “good practice” for a potential real-world scenario, thus preparing the scientific community to respond rapidly to future threats. In other words: we learn to respond quickly, given that we often don't know how to manage the long term. Can it help us?
I would say yes: astronomers believe they have located about 95% of all “planet-killing” asteroids, but not 100%. And obviously it's the missing 5% that worries them, as one could emerge unexpectedly at any time. However, a recent review of all known threatening asteroid orbits brought good news: as far as we know, there are no impacts expected in the next 1.000 years. And apart from the killer ones? The risk of asteroids like Apophis is serious: they still have the potential to vaporize an area of several hundred kilometers in diameter. According to planetary society , the impact would be equivalent to 1.000 megatons, or hundreds of nuclear warheads all exploding in the same place.
Asteroid risk: the frequency of impacts
The Earth passes through about 10 tons of interplanetary dust daily, causing visible meteors almost every night. Larger objects, from the size of pebbles to bowling balls, enter the atmosphere three or four times a day. Impacts of objects the size of a truck they happen two or three times every century, like the event of Chelyabinsk in Russia in 2013. Asteroids approximately 150 meters in diameter they are potentially devastating, but the probability of an impact is about one every 25.000 years. An impact of an object more than 1 km in diameter it could end civilization as we know it, but the probability is once every two million years or so.
Look and learn
To accelerate the RAMSES mission, ESA proposes to reuse the basic design of an asteroid mission already in the pipeline. There Hera probe It is expected to launch in October. Its task is to revisit the double asteroids Didymos and Dimorphos, subjects of an impact experiment (DART mission) in 2022.
The flyby of Apophis offers a unique opportunity to study how its rocky surface is held together, and to observe the consequences of the close encounter with Earth's gravity. As the ESA astronomer says patrick michael: “For the first time, nature is bringing us one and running the experiment on its own.” In addition to RAMSES, already the probe OSIRIS-REx of NASA (which recently sent samples of the asteroid Bennu on Earth) is heading towards Apophis. It is expected to reach the asteroid about a month after its pass by Earth in 2029 and remain nearby for more than a year. One of his missions will be to hit the surface of Apophis with one of its thrusters, allowing the observation of subsurface material.
In summary, the flyby of Apophis in 2029 is an unprecedented scientific opportunity. If before it was a source of concern (I still irrationally retain a bit of a frown), it is now seen as a key event to improve our understanding of the asteroid risk and refine our planetary defense strategies. And without even Bruce Willis.
