Spongebob Asteroidpants

Credit: JAXA

On the surface, the asteroid Itokawa looks like any other of the millions of asteroids floating around the solar system. About 500 meters long, it's not even particularly big. It's a big gray space potato. But little did you know, this asteroid is actually doing an incredible Spongebob impression. 

Let me explain: Itokawa is a rubble-pile asteroid, which means kind of what it sounds like. It's not exactly solid, more a collection of boulders loosely held together by gravity. A lot of the asteroid is empty space. It's porous and thus, extremely difficult to destroy. Yes, it's absorbing blows like it's made of some sort of spongey material. 

I'm mostly writing about this because I thought the comparison was funny, but there are legitimate reasons for studying rubble-pile asteroids. For one, the material is incredibly old, as old as the solar system itself, basically. Since Itokawa is basically indestructible, of course it's going to be made of basically pristine material. Also, it presents a problem for Earth. Itokawa may not threaten Earth in any way, but what if another rubble-pile asteroid is coming our way? Our strategy for dealing with that involves launching a big, heavy object like we did with DART in September 2022 (and quite successfully, I might add, we shortened the moon's orbital period around its host asteroid by 33 minutes). A porous asteroid probably wouldn't react the same way to being shot in the same way. It would likely absorb the blow more efficiently and would be much less effected. That's a problem, and one we'll have to work out. Maybe we could try a pie made in a bomb factory.