I just learned (yesterday[2]) about the rolleron[1], a stabilizing mechanism that prevents roll. It uses the airstream to spin up a gyroscopic mass.

The AIM9 is the only use I'm aware of.

[1] https://en.wikipedia.org/wiki/Rolleron

[2] https://www.youtube.com/watch?v=cfzj3rRIVU4

His long hair dangling by that spinning disc while he demos it... ugh.

Unlike previous Sidewinder iterations with a single-sensor thermal seeker, the AIM-9X has a thermal imaging seeker - it was used to shoot down the much larger balloon last week.

https://www.navair.navy.mil/product/AIM-9X-Sidewinder

So it doesn't really narrow it down that much, then. Could be a plane, could be a balloon.

Could also be a flying promotional bearskin bladder from a local hunting lodge.

Which I have to say is where we may start to see a tragic lack of creativity unfolding on China's part.

Dang, you're correct. It still had a thermal signature, but it wasn't as definitive as what I thought.

If it was not a drone, and "not a balloon", what could it be?

Assuming this was a drone, the "car-sized", "unmanned", "not a balloon", "not maneuverable" (!?), the operating altitude (40k feet / 13 km), and use of AIM9X (IR/heat seeking) should narrow down the possible drones.

Also, one thing I pondered: why F22 instead of F35 to shoot it down? Maybe a question of availability. But, at least publically the F35 operating ceiling is lower than F22, so I was thinking whether the object was in reality higher than the publically known F35 operating ceiling.

> If it was not a drone, and "not a balloon", what could it be?

It could be an unmanned glider with some solar power. Several companies make those. Including Google, which was considering them as data relays back around 2016.

The F22 is America's superiority fighter, still beating the F35 in stealth and capability for anti flying things action. The F22 will probably be the default in most intercept circumstances.

> Brig. Gen. Pat Ryder, Pentagon press secretary, told reporters Friday that an F-22 fighter aircraft based at Joint Base Elmendorf-Richardson shot down the object using the same type of missile used to take down the balloon nearly a week ago.[0]

[0] https://apnews.com/article/pentagon-shoots-down-unknown-flyi...

It's considered a "system-guided" missile, not heat-seeking. It's much more advanced than the original heat-seeking concept and integrates additional optical technology in the fuse.