A spacecraft from the American space agency "NASA" is expected to deliberately collide with an asteroid in less than a year as part of a mission aimed at altering its trajectory, described as "planetary defense". This could allow humanity to avoid future collisions with celestial bodies. This scenario recalls the film "Armageddon," where actors Bruce Willis and Ben Affleck save Earth from a giant asteroid on a collision course.
However, this time it is a very real experiment being carried out by "NASA". Although no large asteroids are currently known to be on a collision course, this operation is part of the preparation for such a possibility. Lindley Johnson from NASA's planetary defense division mentioned during a press conference, "We don’t want to find ourselves in a situation where an asteroid is heading toward Earth, and we have to test this technology for the first time."
The spacecraft has been named "DART," meaning "double asteroid redirect test," and will launch from California aboard a SpaceX Falcon 9 rocket at 10:20 PM local time on November 23. After ten months, the spacecraft will hit its target, located 11 million kilometers from Earth, at the moment when the asteroid is at its closest distance to our planet.
The target is actually a double system: a large asteroid named Didymos, with a diameter of 780 meters, and a moon, Dimorphos, which is 160 meters in diameter. The spacecraft will collide with Dimorphos at a speed of 24,000 kilometers per hour, despite being around 100 times smaller than its target. The collision will result in tons of debris being ejected. Nancy Chabot from the Johns Hopkins Applied Physics Laboratory, which is managing the mission in partnership with NASA, clarified that "this impact will not destroy the asteroid, but will deliver a small nudge."
As a result, the orbit of the smaller asteroid around the larger Didymos will be reduced by "about 1 percent." Thanks to observations by telescopes on Earth over the past decades, it is known that Dimorphos currently completes an orbit around Didymos in exactly 11 hours and 55 minutes. Using the same telescopes, this period will be remeasured after the collision. The researcher expects that the cycle will then take "11 hours and 45 minutes, or something like that." Scientists do not know exactly how much this timing will change, which is precisely what they aim to discover. A number of factors influence this, including the angle of impact, the nature of the asteroid's surface, its composition, and even its precise size, all of which remain unknown.
Andy Cheng from Johns Hopkins University stated that this test will provide "an idea of how much force is required to divert an asteroid from its path to prevent it from hitting Earth," which could be useful "if an asteroid is discovered one day on a collision course with Earth." Cheng explained that a slight change will also occur in the orbit of the larger Didymos around the Sun due to its moon's gravitational relationship. However, he pointed out that this change "is so small that it cannot be measured. Thus, it is a very safe experiment."
Before the impact, the main spacecraft will release a small satellite ten days prior that will use its propulsion system to alter its own trajectory slightly. Three minutes after the collision, the satellite will fly over Dimorphos to observe the impact's effects and possibly the crater created on the asteroid's surface. The total cost of this operation amounts to $330 million. Lindley Johnson believes that if this test is successful, "this technology could be part of a toolbox that we have begun to fill in order to divert an asteroid." He mentioned potential methods, such as using the gravitational force of a spacecraft flying close to an asteroid for an extended period or using lasers.
However, he emphasized that the key lies in identifying potential threats. "The strategy is to find these objects not just years, but decades ahead of any collision risk to Earth." Currently, there are about 27,000 known asteroids near Earth. The 500-meter-wide asteroid Bennu is among two asteroids identified in our solar system that pose the greatest threat to Earth, according to NASA. However, the probability of either impacting Earth from now until 2300 is only 0.057 percent.
