On July 13, 2023, asteroid 2023 NT1 passed by Earth at a distance of 100,000 km, without scientists knowing anything about it. This raises the question: to what extent can we as humanity protect the Earth against small(er) asteroids such as 2023 NT1? Scientists from America may have come up with a solution for this.
In the study, the researchers write that small asteroids, such as 2023 NT1, even if they come very close to Earth at the time of discovery, can still be destroyed using a method known as PI, or ‘Pulverize it‘. In Dutch this means ‘pulverize it’. This method uses a rocket that has a number of piercing rods as payload. Some of these bars are made entirely of one material, others are filled with traditional explosives. As soon as the rocket comes close to the asteroid, the rods are fired and pierce the flying hazard. This ultimately causes the asteroid to break into smaller pieces with a diameter of up to 15 meters.
The big advantage of PI is that it can respond very quickly. For example, the scientists write that even when an impact is several hours away, the asteroid can still be neutralized. Even in that case, most of the remaining debris will burn up in the atmosphere. The shock wave from the debris that might land would not have enough energy to cause significant damage to nature reserves and cities. On Earth, at the moment of penetration, bystanders will mainly see a large light show, which consists of a series of (harmless) bangs and flashes.
PI is not the only way asteroids can be destroyed; Scientists have previously developed another defense technique. Deflection is used for this. A good example of this is the experiment conducted about a year ago with the space rock Dimorphos. In this test one was found DARTspace probe crashed into the space rock at a speed of 6 km/s. The result was a successful change of course of the space rock.
The disadvantage of deflection is that planning, building and launching the space probe can easily take several years, if not decades. In addition, it also costs a lot of money and equipment to build such a space probe. The problem with smaller asteroids is that they cannot always be observed for several years, but sometimes only a few weeks or a few days before impact. Or, as was the case with 2023 NT1, sometimes not at all (see box).
About 2023 NT1
2023 NT1 flew past Earth at a distance of about 100,000 kilometers in July. This brought the space rock about three times closer than the moon! But scientists missed that; they did not discover the space rock until two days later. In this study, the researchers also explain why: the space rock came from the direction of the sun and was therefore, as it were, hidden in the bright sunlight.
In the best case, an asteroid is observed decades or centuries in advance before impact. In that case, deflection might work better, because a smaller change in course is required. The study therefore emphasizes several times that PI is mainly intended as an addition to the available options, rather than a replacement for the deflection method.
However, it is also pointed out that in order to blow something up, you must first be able to observe it. The researchers therefore repeatedly emphasize the importance of good detection methods. There is particular hope for future observatories such as this Rubin Observatory Legacy Survey of Space and Time (LSST) and NASA’s upcoming Near-Earth Object (NEO) Surveyor. So it is very nice that a way has now been devised to neutralize smaller asteroids such as 2023 NT1, but at the same time it still feels a bit like hunting in the dark without a flashlight.