It’s a trope in science fiction that the best way to deal with a threatening asteroid or comet is to simply blow it to pieces. But a new study looking at actual fragments of an asteroid visited by a Japanese space mission finds that the task might not be so simple.
Imagine that you are given a large sponge and asked to blow it into a hundred pieces using just a baseball bat. The job is not that easy because the sponge is porous and highly shock absorbent. It turns out that many asteroids in our solar system are similar to that sponge in that they are made of a loose amalgamation of rocks and boulders.
That was the case of the Itokawa asteroid sampled by the Japanese Space Agency.who visited the rock in 2005 and returned his bounty to Earth in 2010.
“Unlike monolithic asteroids, Itokawa is not a single chunk of rock, but rather belongs to the rubble-pile family, which means it is entirely made of loose rocks and boulders, and almost half of it is empty space. Fred Jourdan, a professor at Curtin University, explained in a statement.
Jourdan is co-author of a new paper on the work published Monday in the Proceedings of the National Academy of Sciences.
Jourdan and his colleagues analyzed small bits of debris and dust brought back from Itokawa. They were surprised by the results showing that the space rock is particularly old and resilient, dating back billions of years rather than the several hundred thousand years expected for similar asteroids.
“Such an astonishingly long survival time for an Itokawa-sized asteroid is attributed to the damping nature of the debris pile material,” says Jourdan. “In short, we found that Itokawa is like a giant space cushion and very difficult to destroy.”
The finding has implications for how we might one day protect Earth from a possible impact from a large asteroid heading our way. For one thing, the long-lived potential of debris pile asteroids means they’re likely even more common than previously thought. That means the idea of simply smashing an oncoming asteroid with the metaphorical equivalent of a huge baseball bat probably isn’t the best approach.
“The good news is that we can use this information to our advantage as well,” explains co-author and Curtin Associate Professor Nick Timms. “If an asteroid is detected too late for a kinetic thrust, then we can potentially use a more aggressive approach like using the shock wave from a nearby nuclear explosion to push a rubble-pile asteroid off its course without destroying it.”
NASA recently tested the kinetic thrust approach with its, and nuclear explosions have often been a staple of science fiction plots involving celestial bodies bringing doom. It’s just that, normally, Hollywood heroes use a nuclear bomb to destroy the object itself.
This new research suggests that breaking space rocks into smaller and smaller pieces may not be the most effective or efficient means of planetary defense, even if it is a great plot device.
If we can’t destroy an oncoming asteroid, maybe we can knock it out of the park.