An asteroid hitting Earth is how life on the planet may one day end in the collective imagination. On the other hand, the most accredited theory on the extinction of dinosaurs is precisely that of the impact of a celestial body with the Earth. The probabilities are very low, but NASA has nevertheless processed data to predict a similar phenomenon.
Few astronomical-apocalyptic themes capture the public and Hollywood imagination like the impact of an asteroid with our planet. Maybe just there depletion of resources caused by human greed that reduces the Earth to a wasteland can compete with the asteroid. Huge rocky masses heading towards Earth, potentially capable of destroying the entire planet, arouse profound fear, although we know that the chances are very low, it is estimated 1 in 100,000.
Sometimes it happened that you heard the news on the news about an object on a collision course with the Earth, only to discover that it was just passing by thousands of kilometers away; for example, on March 23, 1989, Apollo-type asteroid 4581 Asclepius missed Earth by 684,000 km which in astronomical terms are not even many, but in any case not so few as to really represent a danger. Despite this, NASA, which still has the task of monitoring everything that happens in space, has therefore perfected “safety systems” over the years to prevent such a catastrophic event from happening.
Modern technology is allowing us to locate and monitor near-Earth objects which could represent a threat. There is a complex mathematical theory behind determining the trajectories of asteroids and comets that scientists study in depth to develop precise calculations.
Tracing the trajectory of celestial bodies
Once an asteroid or comet has been spotted, the next step is to calculate its trajectory and predict whether it will approach Earth’s orbit at a critical moment. This task falls to the NASA Center for Near-Earth Object Studies (CNEOS). At the head of the center there is Paul Chodaswho leads a group of mathematicians who process telescopic observations to calculate the trajectories of objects.
Determining the trajectory is an intricate mathematical problem that requires precise models of the solar system, including the position of the Earth, the Sun and especially the Moon. To make long-term predictions, it is necessary to know the positions of all the planets, since each of them affects the motion of the asteroids.
To obtain more accurate trajectories, it is essential to have more data, both through multiple observations of the same object on the same night and through observations by different observers. The laws of physics, especially those of gravityplay a crucial role in constraining the trajectory of celestial objects.
In addition to asteroids, comets represent another potential threat to Earth. These celestial bodies, composed of ice and rock, can cause widespread damage if they impact the planet. Predicting the trajectories of comets is particularly difficult because of the process called degassingin which heating causes ice to sublimate into gas, creating the characteristic tails of comets. These gases can influence the trajectories of cometsmaking predictions more uncertain due to nongravitational acceleration.
Comets mainly come from the Kuiper Belt or Oort Cloud, well beyond Neptune’s orbit, and often approach Earth at different angles than asteroids. This variety of trajectories adds complexity to predicting their movement.
Process automation: is it possible to predict the impact?
With over 1.3 million objects in the solar system’s main database of celestial bodies, manually calculating trajectories for each of them would be untenable. Therefore, much of the work is automated using powerful computer systems. The good news is that large asteroids that could pose a threat have almost all been identified, offering some degree of reassurance. Attention is now shifting to medium-sized asteroids, which could cause significant damage if they hit a densely populated area.
Defending the Earth from asteroid impacts is an ongoing goal of NASA. While modern technology allows us to detect and track near-Earth objects, further significant unknowns remain to be resolved. Efforts are now concentrated on improve the detection of medium-sized asteroids and on the development of technologies to deflect possible threats. While a dinosaur-killing event is not expected in the near future, preparedness and vigilance remain key priorities for the safety of our planet, according to Paul Chodas.
The next missions of the Center for Near-Earth Orbit Surveyor (NEOS) will significantly improve the ability of experts to detect these medium-sized bodies. And testing of asteroid deflection technologies, such as the Double Asteroid Redirection Test (DART), demonstrate that it is theoretically possible – at least if you have sufficient advance warning – deflect a celestial body incoming causing it to crash with a spacecraft.
The DART was an incredible achievement, but it is not yet a defense system. In tests, he was able to change the course of an asteroid, but not enough to prevent an impact with Earth if it were a real threat.
