NASA has just approved in its Advanced and Innovative Concepts Program an idea that could deal with the threat of a newly discovered body that threatens Earth
During a few tense days in January, the newly discovered asteroid 2022 AE1, 70 meters long, almost suddenly became the most dangerous of the last decade: the first analysis indicated a potential impact with Earth on July 4, 2023. A year and a half that fell short to apply any strategy designed to divert the orbit of dangerous asteroids or comets. Although the whole story may seem like a script that mixes different blockbuster science fiction movies, this chapter has really happened. Just a few months ago, the European Space Agency (ESA) -in the role of the protagonist- found this space body, and the calculations indicated that, indeed, the crash would occur.
However, after analyzing them in-depth, the ESA determined that the asteroid will pass ‘close’, but safely at about 10 million kilometers, more than 20 times the distance of the Moon.
Although this chapter has had a happy ending, the probability of a similar event occurring exists. In the last decade, the main space agencies have begun to take planetary defense very seriously: it is not for nothing that there are billions of objects in space that could cause damage ranging from the disabling of satellites to the end of life on Earth, as demonstrated by the meteorite that wiped out the dinosaurs 66 million years ago. That is why there are several proposals to deal with a possible event of this type: from kinetic impactors ( NASA’s DART mission is on its way to test this technology) to nuclear warheads. Now, the US space agency has just included a new one in its NASA Advanced and Innovative Concepts (NIAC) Program: exploding the space body that threatens us into thousands of pieces.
An ‘in extremist plan
The plan, developed by the team led by Philip Lubin, from the University of California Santa Barbara, basically consists of placing a set of bars in the trajectory of the asteroid or comet that, when impacting head-on against the object at high speed, would penetrate he. Upon insertion, they would detonate, causing the body to break into smaller fragments. The technique, dubbed PI-Terminal Defense for Humanity (‘PI’ as a contraction of ‘Pulverize It’ or ‘pulverize it’), could be applied to objects 50 meters in diameter, it would be 5 hours before the impact, and 60 days before of the impact for objects of 1 kilometer in diameter.
In other words, unlike the rest of the plans that seek to divert the trajectory of the asteroid and that require at least several years of programming and development, in addition to a fairly large distance, PI would shorten the reaction to hours and kilometers. But with restrictions: the time needed to destroy an object would increase as its size increases, and the minimum distance at which this technique could be applied would also increase. This is one of the factors that make the plan more controllable at shorter distances because in those cases we would be facing smaller objects, which would break into smaller pieces. Its creators posted their idea on the ‘ ArXiv ‘ preprint site.
“This is a method that, according to the author, could work in situations in which there would not be enough time to react with the technologies that had been considered until now and that are beginning to be tested to protect us from the impact of large objects,” explains to ABC José María Madiedo, an astrophysicist at the Institute of Astrophysics of Andalusia IAA-CSIC. “However, this innovative method, following the NIAC procedures, must be reviewed and subjected to further studies to see if it is finally viable or not. It is not, therefore, something that can be applied in the short or medium term.
The drawbacks of IP
Because this plan, although interesting, still has some pitfalls that today would be a serious problem. For example, the author recognizes that it would be necessary to develop some material with which to build said bars, which would collide with the asteroid or comet in hypervelocity conditions (more than 40,000 kilometers per hour). “According to our current experience in hypervelocity collisions, materials are instantly pulverized or vaporized at the point of impact, without being able to penetrate sufficiently into the body they collide with. This supposes an enormous challenge that this technique would have to overcome”, affirms Madiedo.
And the idea itself would also be dangerous. Because detonating a body and creating thousands of small, uncontrolled pieces could still pose a threat. As an example: the meteorite that fell on the city of Chelyabinsk was 17 meters long and caused an energy equivalent to thirty atomic bombs like the one in Hiroshima, causing damage to thousands of buildings. “In effect, we could not control the trajectory that each fragment would follow -indicates the IAA-CSIC astrophysicist-. Some would change their course just enough to avoid hitting Earth. Others would maintain their trajectory practically intact and would end up entering the Earth’s atmosphere. The author of the work considers that these fragments would be small enough (10 meters in diameter at most) so that the atmosphere can disintegrate them before they hit the ground. However, one of the weak points of this method is that it is impossible to know exactly how the object is going to break, since neither what its interior is like nor how resistant it is known.
And, despite everything, this method would not be valid for asteroids or comets larger than one kilometer. So, for the time being, this plan would not be effective to end the threat of a meteorite of the same size as the one that killed the dinosaurs, which had a diameter ten times greater.
