It’s amazing how much a single movie can affect the cultural content of an entire topic – even a topic as serious as planetary security. The popular media always uses the 1998 movie Armageddon as a reference when talking about how we can destroy a civilization-ending asteroid. That’s despite the film’s glaring scientific flaws, not the last of which would be the size of a rogue comet threatening Earth. MIT planetary defense researchers were recently interviewed by the university’s media department as part of the “3 Questions” series. One of the most important points to take away is that the size of any possible planetary influence on our lives will be much smaller than the mile-sized behemoth that shaped Bruce Willis.
These tiny objects, known as decameter-scale asteroids because they’re usually 10 meters across, aren’t the kind that destroy civilization — they’re usually on the scale of kilometers and up. But they are very common. MIT researchers believe that they affect the Earth-Moon system almost every two decades, compared to the once in ten million years a large asteroid would hit us.
Obviously, these decameter-sized objects are larger than the ones that have caused a large number of firebombings over US cities. For example, the one that exploded in my hometown of Cleveland a few weeks ago, which was loud enough to shake houses in the area, was only 2 meters wide.
Another recent example of an asteroid of this size is 2024 YR4, which was discovered more than a year ago, and reaches between 53 and 67 meters – the size of a 15-story building. According to MIT researchers, this group of objects is unlikely to cause human harm. However, if they were to hit a populated area, they certainly could, as they could release the equivalent of 8 to 10 megatons of TNT.
But what they are sure to do is destroy space infrastructure – including satellites used for GPS and communications. In the worst case scenario, it could be the spark that ignites a Kessler syndrome – an orbital signal that could prevent us from finding space for decades or more. So even if this type of asteroid gave birth to a few satellites, it would be good if we knew it was coming and could do something about it.
The problem is that they are really hard to see. At this level, these asteroids don’t see much light, making it difficult for telescopes to track them. Other space-based telescopes, such as the James Webb Space Telescope, do better. It was used by some members of the MIT team to track 2024 YR4 and recently suggested that it has no impact on the Moon in 2032. But, since JWST is our most capable deep space telescope, its time requirements are so frequent that it cannot be used regularly to observe decameter scale asteroids.
Another ground-based telescope coming online soon should help, though. The Vera Rubin Observatory is expected to find 10 times more decameter-sized asteroids than we have found before. However, while it is useful to detect very faint objects such as these small asteroids, it is not easy to track them, making it difficult to determine the size of the asteroid or its trajectory.
To make up for this shortcoming, the MIT team is developing a pipeline of other telescopes, such as the MIT Haystack and Wallace Observatories, which should be able to track the asteroids that Vera Rubin finds. That pipeline will include data analysis to make sure they’re tracking real objects and not artifacts from telescopes or other noise.
Knowing what to do when they find a decameter-sized asteroid about to hit Earth (or the Moon) is an entirely different matter. It is almost inevitable that we will. MIT researchers expect that, within the next decade, astronomers will identify several small objects on the way that will affect the Earth-Moon system this century. So far, there is no plan for the nations of the world to deal with this opportunity. But what the planet’s defenders can be sure of is sending Bruce Willis and his hand-picked team to take care of it won’t help.
Learn more:
MIT – 3 Questions: Strengthening our planetary defenses
UT – We Need Urgent Asteroid Response Work
UT – Should Planetary Protection Take Center Stage?
UT – Rome Telescope Joins Global Asteroid Defense Team
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