Object that fell from the skies identified as separation ring from a rocket (opens in new tab)

For reference, here is a ring which is believed to have come from China's Long March BuNo Y77. Note the similar scale, and similar discoloration. https://spacenews.com/india-examining-crashed-space-debris-s...

I design and build all sorts of hardware relating to air-breathing (jet) propulsion, including gears. I agree with mkl. Those are not gear teeth. They have flat flanks, and no involute profile. No one makes gears with a gigantic U shaped root. They appear to me to most likely be clearance slots, to go around protruding bolt heads on a mating part. I have designed similar counterbore features myself.

What makes you claim that this part is steel? The article does not say that. Is that a fact, or are you guessing?

An earlier article [1] linked in this one says about 1.2m radius, so ~2.4m or ~8ft diameter. At 48 seconds in the video there's a man standing next to the propped up side and it comes up to his chest, so that seems believable (the other side is down a slope).

It seems surprising it weighs 500kg though, as it's held up by a thin iron/steel pipe/bar. If it's solid mild steel at 7850kg/m^3, with an outer radius of 1.2m and inner radius of 1.05m, and a thickness of 4cm, that would be (π*1.2^2 - π*1.05^2)*.04*7850 ≈ 333kg. If the inner radius is 1.0m and thickness is 5cm, that would be ~543kg, so maybe it is that heavy.

Edit: The tooth profile looks strange for a gear. There's a clear but potato-resolution view at 36s in the video. The teeth have flat tops with sharp corners, the sides are pretty vertical, and the gaps have very rounded bottoms.

[1] https://nation.africa/kenya/counties/makueni/mystery-object-...

Lots of rocket components look like gears. The outside skin of the rocket often had internal vertical stringers and so components need cutouts that end up looking a bit like gears

You're just making stuff up? Photos show diameter is larger than human height, maybe 8'. Only indication it's "solid steel" is you said it is.

The rust does stand out as kind odd, not many aerospace materials rust???

How fast would you have to spin a gear ring to say, launch it on a ballistic trajectory and have it go supersonic? Maybe a factory somewhere had a _really_ catastrophic accident?

2.5 m (8 ft 2 in) in diameter:

https://en.m.wikipedia.org/wiki/M-V

Maybe it was something like this?

https://old.reddit.com/r/nextfuckinglevel/comments/1bmpxaq/t...

The diameter seems to match.

I thought it might be an jet-engine cowl, but I don't know enough about planes.

The rivets and joints are very much aerospace style.

Could be from a concrete mixer. (Credit: rando YouTube comment.)

I asked Johnathan McDowell, who tracks space objects alongside his main job working on Chandra. He's much less convinced it's from a rocket.

https://bsky.app/profile/planet4589.bsky.social/post/3leq2wb...

There's not any great candidates.

It would have been supersonic at a very high altitude and likely came in at a steep angle, so sonic boom + large exposure area + long path.

While it was supersonic it would have produced a sonic boom all along it's path of travel.

Sonic boom(s). Unsure what the speed is, but could have been significantly higher than terminal velocity at sea level.

Somewhere in between the launcher and the target. Ballistic missiles fly a near-parabolic sub-orbital trajectory. That also means that everything on the missile reenters and crashes (or reaches the target) within minutes of the launch. This is a matter or energy management. If your payload (the warhead) is going to land somewhere on Earth, why waste energy in flinging it on a high-velocity (possibly orbital) trajectory when that energy could be used to loft more of the payload (a heavier warhead) directly at the target?

There are a few cases where this concept of lowest-energy trajectory is not followed. One of them is a lofted-trajectory launch. The missile flies a higher ballistic trajectory than what's necessary to reach the target. This is sometimes used for missile tests or for target ranges less than the missile's maximum range. However, this is also a sub-orbital trajectory and behaves more or less the same as before.

Another case is the Fractional Orbital Bombardment System (FOBS) where the warhead enters a low orbit and then deorbits towards the target. Space debris situations like in this story (where the rocket body lands well away from the target, long after the launch) can possibly occur in FOBS launches. However, this isn't very energy efficient. It's main advantage is that it's harder to detect and intercept, since its orbital trajectory is much lower than a pure ballistic trajectory. Even then, some countries can knock them out in orbit using ASAT (anti-sat) detectors and interceptors. It's not that commonly used, except in combination with other technologies like hypersonic gliding and waveriding.

How many people will have to be fatally injured before international laws put seriously painful financial fines on companies dropping crap from space? Or will my fantasy come true that all roads, infrastructure, homes and businesses move underground?

There are laws against littering.

My first thought was “Wow, that’s a lot bigger than a coke bottle.”