Waking up one morning and finding out that an asteroid could hit Earth in a few years isn't exactly the best way to start your day. Yet, that's exactly what happened last December, when observations estimated a 3,1% probability that the asteroid 2024 YR4 could hit us in 2032. It doesn't seem like much, does it? But in terms of planetary defense, it's like playing Russian roulette with a 32-shot pistol to your head. Fortunately, this time the cosmic roulette turned in our favor. But what if the calculations had confirmed the impact? Would we have been completely defenseless like the dinosaurs 66 million years ago, or has our species finally learned to protect itself?
The Planetary Defense That Dinosaurs Dreamed of
There's a joke going around among astronauts: “If dinosaurs had a space program, they'd still be here.” The astronaut Ron Garan cited it years ago, and it has become a mantra for those involved in planetary defense. Because, let's face it, dinosaurs had a big problem: brains the size of walnuts and arms too short to build rockets. We humans, with our slightly larger brains and opposable thumbs, are much better off. And it's not just a question of anatomy. Over the past few decades we have built something that no other species on the planet had ever even imagined: a warning system and potential defense against cosmic threats.
The recent case of asteroid 2024 YR4 is proof that this system is working. Discovered on December 27 by theATLAS (Asteroid Terrestrial-impact Last Alert System) In Chile, this space object between 40 and 90 meters in diameter initially set off some alarm bells. And no, it's not a disaster movie exaggeration.
The warning system that works (while some media sleep)
I always like to underline how real scientific information works compared to sensationalism. While our planetary defense system worked tirelessly to refine the calculations on 2024 YR4, some major newspapers and websites "curiously" forgot the fact that after just a week the risk represented by this asteroid was no longer there.. Some alarmist headlines remained online (and in some cases still are) to fear a 3,1% probability of impact, while the scientific reality told a completely different story. The percentage of risk had fallen to 0,004%, practically zero. But hey, bad news gets more clicks, right?
We have taken care to constantly update ourselves on real data, because correct information is the first form of "planetary defense". Sometimes we ask ourselves "why do we do it", then we remember that there are you, beloved readers... eh eh.
How Planetary Defense Really Works
Protecting our planet from asteroids is not the stuff of movies with Bruce Willis (when it hadn't yet been cloned by AI) that heroically sacrifices itself. It's a much more methodical and less dramatic (but definitely more effective) process. First, the object is detected with systems like ATLAS, NASA-funded telescopes around the world that scan the sky 24/7. Then the orbits are calculated, and the trajectory is progressively refined with new observations.
The case of 2024 YR4 shows exactly how this process works: initial detection, alert, further measurements from observatories of NASA, ESA (European Space Agency) and JAXA (Japan Aerospace Exploration Agency), and finally the verdict, in this case reassuring. An example of international scientific collaboration that deserves more attention than it receives. But what if an asteroid were actually on a collision course with us? Here too, planetary defense has made remarkable progress.
From “Project Icarus” to DART: Detour Instead of Dying
The idea of deflecting an asteroid is not new. In 1967, MIT students dreamed up “Project Icarus,” a plan to launch six Saturn V rockets with 100-megaton nuclear warheads at a hypothetical threatening asteroid. It was practically science fiction., sure, but the basic idea was solid: you don't have to destroy the asteroid, just nudge it slightly off course.
This intuition became reality on 26 September 2022, when the mission DART (Double Asteroid Redirection Test) by NASA successfully hit the asteroid Dimorphos, altering its orbit by 32 minutes. It was just a test, on an asteroid that posed no threat, but it proved that the concept works. Of course, the technology is not perfect yet. The impact of DART It also generated a swarm of debris, showing that hitting an asteroid at over 23.000 km/h can have unforeseen consequences. And a really large asteroid would require a force far greater than we can currently generate.
A cosmic insurance for humanity
We live in a cosmic shooting range. The Earth has suffered devastating impacts in the past: the asteroid that probably wiped out the dinosaurs (but maybe there were two), that of Vredefort in South Africa (20-25 km) over 2 billion years ago, or that of Sudbury, Ontario (10-16 km) 1,85 billion years ago. Even the event of Tunguska in 1908, caused by an object of “just” 40 meters, cut down 80 million trees in Siberia. For the first time in the history of our planet, however, one species has developed the ability to detect these threats in advance, and is perfecting the means to neutralize them. Planetary defense is perhaps the grandest (and least celebrated) insurance project in human history.
We may not be completely asteroid-proof yet, but we are making impressive progress. And that, in an age of often depressing news, is something to celebrate. Also because, unlike the dinosaurs, we have no intention of simply waving our (thankfully not small) arms in the air while we wait for the end.
