Prepare to face the threat of an asteroid on collision broken with the earth It is not a science fiction scenario, but rather a realistic possibility, as evidenced by the recent case of the Asteroid 2024 YR4. The latter, initially given on a collision course with the earth with a 3%probability, was declassified in risk thanks to the observations of the James Webb Space Telescope And it currently has a 4% probability of hitting the moon. Without a alert system that individuals of this type and without the possibility of following its orbit with the most powerful telescopes at our disposal, we would be completely vulnerable to these threats. Improve planetary defense skills it is therefore one mandatory necessity and the recent exercise carried out at the Planetary Defense Conference In Cape Town in South Africa, from 5 to 9 May 2025 it made the objective of that of refine techniques, deflection strategies and control line in the case of a potential future threat. By simulating an asteroid of diameter of 150 meters, the simulation showed how the different Deflexion techniques at our disposal I am able to move the asteroid From the original impact corridor, saving the planet from a catastrophic impact potential.
How and when the exercise took place
The recent Planetary defense exercise It took place during the ninth International Academy of Astronautics (IAA) Planetary Defense Conference, held near Cape Town in South Africa, between the 5 and 9 May 2025. In addition to various presentations that have analyzed the possible risks of impact of the 2024 YR4 asteroid and the physical, astronomical and astronautical aspects, but also political and economic, of a hypothetical impact of a medium/small sizes with our planet, scientists organized a consistent exercise in one simulated scenario in which the June 5, 2024 a medium -sized asteroid on a collision course with the earth 17 years after the discovery.
The details of the simulation
The simulation begins with theIdentification on June 5, 2024 of an asteroid of magnitude 21.5 by the Sky Survey Catalinato which the name is assigned 2024 PDC25. Initially this object does not arouse concern because it seems one of the many discovered by this project of mapping of the sky for the search for asteroids and comets and in fact his own probability of impact I am lowabout one on ten thousand for April 24, 2041. However, with the passage of the days andIncrease in observations from the ground, the estimate of the orbit of this object is finished, and the probability rises to one percent At the end of July 2024, high enough to attract the attention of theInternational Asteroid Warning Networka collaboration of the United Nations for the planetary defense. For the 1st August 2024the various observations raised the impact probability at 1.6%confirming the potential Impact date for April 24, 204117 years old starting from the discovery. However, the asteroid is in departure, just as it happened for 2024 YR4, so the only certain estimates on the nature of this object come from “urgent” observations carried out with the James Webb Space Telescope showing how 2024 PDC25 is a Roccious steroid of type S, with a diameter between 90 and 160 metersand with a probability of impact that seems higher in reality by 1.6%.
This object concerns the international community and therefore it Space Mission Planning Advisory Group of the European Space Agency recommends the launch of a probe to intercept and study the asteroid Near the Perigeo, which takes place every two and a half years. The probe is launched in September 2027 and reaches the asteroid on April 12, 2028 by confirming the rocky nature of the object and esteem the diameter in about 150 meters. There is worse. The observations repeated during the four years following the discovery leave no doubt, the asteroid now has the 100% of impact probability with the earth.
By combining these observations with the probe measures, scientists manage to estimate that theasteroid will fall between the Congo and the Angola freeing an energy to the impact between the 45 and 160 megatonstens of thousands of times the energy released by the Hiroshima atomic bomb. Such a cosmic giant would cause a impact crater of 3 km in diameter, Very serious damage within a ray of 130 km from the impact, not to mention the dust and the shock wave released in the atmosphere which however would not cause climate changes at a global level. The impact estimate a number of victims ranging from several thousand to over 1 million.
Possible deflection strategies
There are now 13 years to impact and urgent the asteroid from its destructive race. The optimal moment To do this it is al perigee the highly eccentric orbit of the asteroid. The Perigee takes place after about 2 and a half years for this object, therefore in November 2032, December 2034, January 2037 and March 2039. The more we are to the impact date, the greater the deviation required to avoid the impact. Scientists therefore propose Three techniques To vary the speed of the asteroid: thekinetic impactorthenuclear explosion or the ions flow. The primary request is that in implementing any of these options theasteroid is not divided into several large fragments on a collision course. The most obvious choice in a real scenario would probably fall on the kinetic impactor, the option that would have the highest probability of success since it has already been tested with the Dart probe and the Asteroid Dimorphos.
In this simulation though All three deflection methods are evaluated and the good news is that each of them is potentially able to move the asteroid from the original impact corridor. Forkinetic impactorwould be necessary from 4 to 7 spatial missionswhile to move the asteroid by bombing it with a ions flow, they would be enough from 2 to 5 probes. As for thenuclear optionwe must not think of a film scenario that completely disintegrates the asteroid, but rather to an explosion at a short distance that, by emitting X -rays, vaporizes a part of the surface of the asteroid thus generating a push in the opposite direction. For this option, A single mission It would be enough to deflect the asteroid.
What we learned from the exercise
The good news that we can draw from this exercise is that for medium -sized asteroids, around 150 meters, Man has technology to cause significant deviation of an asteroid on a collision course with our planet. This though presuppose that the object is discovered well in advancesince the closer to the impact date we are, the greater the variation in speed to be imprinted to the object to deviate it from its original orbit. “Preventing is better than taking care” It also remains valid in this area: it is necessary to push the accelerator on the development of increasingly sophisticated alert systems that allow to Find out well in advance Potential threats of impact, thus giving us time to prepare strategies to deviate asteroids from their destructive races.
