Thursday, February 18, 2010

Sound ripples in cloud during rocket launch



"Perched on top of an Atlas V rocket, on February 11 the Solar Dynamics Observatory launched into space. About a minute after leaving the Earth, the rocket did two things: it passed the speed of sound, and screamed past a sundog, a rainbow-colored optical effect in the sky caused by ice crystals.

And when it did, well, it was incredible. What’s below is just about the coolest video I have ever seen. And I mean that seriously. Click the "720" button and pay close attention at the 1:50 mark. You won’t miss it, the crowd in the audio will alert you…"

A very good video from BadAstronomy

Can you imagine the power involved in this? Those hundreds or thousands of pounds per square foot of pressure on that rocket really add up, and exert serious force even miles from the nosecone. However, there is no reason to believe that this is a sonic boom, as suggested in the link. This could just have been the sound from the rocket engines, and it is important to understand that a sonic wave should probably just look like a single expanding circle, as it is a single expanding cone. There may be some texture to it, and maybe a few cones dropped by different parts of the rocket, but there again is no reason to think that this shows us that! It may be something else, in other words, perhaps the sound from the rocket engines? Or maybe it really is just a turbulent cone of compressed air that is being pushed off every nook and cranny of the rocket airframe at different times. These cones do look turbulent when I have seen them, with supersonic projectiles and also with a rocket sled. Either way, it would be great to see what the experts think.

Looking at the video again, it seems the waves continue well after the rocket has past the clouds. That leans towards the engine sound side of the argument. Or perhaps a combo?

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