If a NASA video shows objects changing speed/direction, is that proof of propulsion systems or is there another explanation?

Depends on the scale of the direction/speed change.

Gravity.

Solar wind.

Collision.

If you video tape a leaf falling out of a tree, is that proof the leaf (or the tree, for that matter) has a propulsion system?

I’m a skeptic, I’m just trying to wrap my head around some strange video’s i’ve seen.

@MrItty I’m referring to objects in space

@Ansible1 and in your mind the difference between the two is…. what, exactly?

@MrItty
the lack of atmosphere?

@robmandu
i have seen the videos. a lot of objects make abrupt 90° course changes.
Gravity results in ballistic movement, e.g. a curve. So does solar wind, but much less noticeable.
collisions require a specific impact angle to result in a 90° course change, which may happen once, but many times in less than a minute? highly unlikely. Furthermore, collisions between space debris would almost always result in smaller debris splintering off the main objects, which was not observed.

Also, many of the abrupt, angular motions that objects are supposed to have made are illusions caused by the way our eyes process visual information. To prove this to yourself, isolate one star, and stare at it for a time. If you are like most people, it won’t be long before you see it appear to accellerate and take an abrupt turn.

@pdworkin
illusions?
i doubt it.

@ragingloli what, in your mind, does atmosphere have to do with motion?

A leaf falling down within an athmosphere will create turbulences and pressure differences which in return will severely affect the leaf’s falling motion and causes it to zig zag. In short, basic aerodynamics. It’s the stuff that makes planes fly.

You mean NASA videos like these?

Thing is, I’m not much swayed by “what else could it be?” kind of arguments. That’s all conspiracy theory hokum.

I see a lot of flat 2-D grainy, greyscale video. Objects of interest are so out of focus at some points, that they are transparent. In my experience, that only happens with very small objects at a very close distance.

I’d be much more interested in seeing more if it was shot by a Discovery crew with HD/IMAX equipment, both from the shuttle and the space station with their feeds sync’d up. Then we’d have a much better estimation of speed, scale, shape, etc.

To me it looks quite like the camera has changed angles. Since each frame is overlaid on top of the others the Earth appears to remain stationary (although you can see a bright ring begin to appear across the globe where the picture of the Earth is no longer being overlaid in the same place). The large white light source in the corner of the video (most likely the sun) near the end proves that the camera is changing angles. Throughout the video the lens flare appears to be moving at roughly the same velocity as the particles.

@ragingloli An object with a propulsion system must undergo extreme forces to make an abrupt 90 degree turn. Just try it in your car and see how the tyres complain. The object in the upper middle of the screen made a >270 degree turn, and doubled its speed – which can only imply a collision. The space shuttle would do the same thing in some failed re-entry scenarios.

@FireMadeFlesh
that would require a second object. it would also result in additional debris splintering from both objects. yet neither of these can be seen.

”The space shuttle would do the same thing in some failed re-entry scenarios.”
It would also disintegrate into several parts, amply demonstrated by the last failures of the space shuttle.

@ragingloli The second object does not have to be visible. It may either be of a similar colour to the background, which is possible with such a low quality image, or it may not be of the visible light spectrum. Debris would obviously not be seen, as the object is glowing and its corona would obscure the smaller light profiles of debris fragments.

As for the space shuttle, I am talking about scenarios where it enters at a shallow angle, less than 7 degrees I think, and so ricochets into space. If the mass in the background has a more dense atmosphere, this would be possible at steeper angles. If there was significant turbulence in this dense upper atmosphere, and the object hit a high pressure system then it is possible that it would ricochet at large angles without overheating.

Then again, this footage is on YouTube, not the NASA website, so its validity cannot be verified. For all we know, it may be as genuine as this famous example.

@FireMadeFlesh
”Debris would obviously not be seen, as the object is glowing and its corona would obscure the smaller light profiles of debris fragments.”

I don’t think it is glowing. I think it reflects sunlight.

@ragingloli Whatever it is, the object is emitting or reflecting a large amount of light towards the camera, which will obscure any debris.

@ragingloli The camera is an infrared camera. It composites many previous pictures on top of each other because the objects are very faint. It appears that the video is a timelapse over a long period and not really a video in real time. Objects absorb sunlight and emit infrared radiation, so yes, it is glowing.