In the vast expanse of space, Earth is constantly at risk from rogue asteroids. These space rocks have caused massive destruction in the past. The dinosaurs, for instance, were wiped out by a massive asteroid impact around 66 million years ago. This event, known as the Chicxulub impact, caused an "impact winter" that blocked out the sun and led to a drastic cooling of the planet. The dinosaurs, unfortunately, had no way to defend themselves. But what if they had a space program? They might have detected the incoming asteroid and taken action to avoid their doom.

        Humans, fortunately, are in a better position. We have the technology to detect and potentially deflect asteroids. Recently, an asteroid named 2024 YR4 briefly appeared to be on a collision course with Earth. This asteroid, discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile, had a 3. 1% chance of hitting Earth in 2032. This might not seem like a high risk, but it was three times higher than any other known asteroid. Scientists from NASA, the European Space Agency, and the Japanese Aerospace Exploration Agency quickly gathered data and calculated the asteroid's trajectory. The probability of impact eventually fell to just 0. 004%.

        The recent scare over asteroid 2024 YR4 highlighted the importance of planetary defense. Asteroids follow predictable orbits, and with enough data, scientists can calculate their paths with great precision. This allows us to predict potential impacts decades in advance. The key to planetary defense is not to destroy the asteroid, but to give it a slight nudge, altering its orbit just enough to avoid a collision. This is known as a "kinetic impactor" method. NASA's Double Asteroid Redirection Test (DART) successfully demonstrated this method in 2022. DART collided with the asteroid Dimorphos, shortening its orbit by 32 minutes. However, the collision also released a swarm of boulders, showing that there are still challenges to overcome.

        The discovery of the Chicxulub crater in 1990 and the sight of the Shoemaker-Levy 9 comet hitting Jupiter in 1994 convinced Congress to take the threat of killer asteroids seriously. In 1998, Congress directed NASA to detect and catalog at least 90% of near-Earth objects (NEOs) that were more than a kilometer wide. NASA and its partners hit that goal with time to spare, and so in 2005, Congress directed the agency to identify at least 90% of all NEOs 140 meters or wider. Though over 18, 000 NEOs have been identified, about 40 every week, there may be a million or more out there. That mission continues.

        The recent scare over asteroid 2024 YR4 was a wake-up call for planetary defense. It showed that our detection systems are working, but our defense systems still need improvement. The good news is that we have the technology and the knowledge to protect ourselves from this natural existential risk. With continued research and international collaboration, we can ensure that the next close call doesn't become a catastrophe.

Asteroid 2024 YR4: A Close Call and a Wake-Up Call

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