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Melbourne satellite re entry?

Old 12th Jul 2014, 10:59
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The rock would be falling straight down by this stage so would be far more likely to hit the aircraft on an upper surface than the nose or leading edges. How much damage does hail do? The 5mm meteorite would weigh about as much as a 10mm hailstone.
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Old 12th Jul 2014, 11:10
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Hydromet, given it was seen over a very wide area would mean it was high. Probably something like 100km up. The sound would take around 5 minutes to reach the ground. One possibility is the plasma trail produced by the meteor/space junk can emit radio waves which can induce vibrations in objects on the ground so you may have heard that. Of course it might just have been a totally unrelated sound.
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Old 12th Jul 2014, 11:37
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The rock would be falling straight down by this stage so would be far more likely to hit the aircraft on an upper surface than the nose or leading edges.
Arrr, the old falling down trick. Shine your torch out the window when doing 450TAS when it's raining: she's coming straight at you, horizontally (plus or minus a few degrees).
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Old 12th Jul 2014, 11:43
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Question

I have no idea if the following is correct; but I was once told by someone who appeared to know what they were talking about saying that meteors/meteorites generally burn with a white light whilst space junk quite often has a colour (mainly green but occasionally red, yellow or purple) to it because of the various alloys used in construction of whatever it is that is re-entering the atmosphere.

I am quite sure that there is a ppruner who could confirm, deny or expand on this with some authority.
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Old 12th Jul 2014, 11:56
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Rain is falling at maybe 1/10th the speed of the meteor so what you say is true for rain. For said meteor it's travelling downwards at about 25% of the forward speed of the aircraft, so unless you're flying an aircraft with a very fat wing and short fuselage it's more likely to hit the top than the front.
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Old 12th Jul 2014, 12:01
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Thanks, leP. I suspect that what I heard was ambient white noise (wind, etc) which I hadn't noticed until I started listening.
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Old 12th Jul 2014, 12:31
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Pinky, for both meteors and space junk it's all to do with their composition. Most meteors (85%) are stony, so are composed of a mix of elements meaning you don't get a particular colour standing out. For space junk you have large pieces of specific materials so will get the colours characteristic of whichever element is being vaporised at the time.
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Old 12th Jul 2014, 13:00
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le Pingouin is on the money. It's all about the composition. Small fast meteors (aka shooting stars) generally appear single colour. The most common flash is white - probably for a couple of reasons including the fact that they appear and disappear so quickly, and they are usually not in the centre of the eye where your colour vision is the most sensitive.

For more persistent meteors colours are commonly reported, but generally a uniform colour, depending on the concentration of the predominant metal. Nickel gives off a green tinge - there was a large green meteor crossing the northern sky in Melbourne about 6 years ago that got a similar amount of media attention.

The speed of the meteor might also influence its colour hue, as a slower meteor might not vapourise the metals simultaneously (or at all).

I've seen random falling space junk before - once even in daylight. The multi coloured sparks trailing off it (rather than a vapourised tail) were quite spectacular, but a more homogenous metal structure would not be as colourful.

There are also many reports of an instantaneous sound being emitted from large meteors. Not the delayed sonic booms as the news footage from the Russian one last year showed, but an actual sound being heard whilst watching it - usually likened to a frying pan sizzle. Nothing's proven, but clearly can't be sound waves due to the distance and light/sound speed difference, so the likely candidates are a type of VLF radio wave (travels at the speed of light) that's interacting with the inner ear somehow. I've never heard it though (but don't doubt some can).

As an unrelated tidbit, Chris Hadfield (the Canadian musician/astronaut of Bowie remake fame) mentioned in his book that as you drift off to sleep in space, sometimes you see little flashes of light faintly with your eyes closed. These are solar radiation particles hitting your optic nerve and triggering a sight sensation in the brain. We terrestrial dwellers don't see them as we live under more of the magnetic field that protects us.

For those in the flight deck on red eyes - you are more likely to see a meteor in the pre dawn night sky, as that's the leading edge of the earth and more likely to run into objects. For a meteor to happen at dusk, it's got to catch up to the earth (or be sucked into a decaying orbit). On those Perth Sydney red eyes, dim the cockpit lights, lean over the glareshield and stare outside. Magic.

Last edited by compressor stall; 12th Jul 2014 at 13:13.
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Old 13th Jul 2014, 01:40
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Jumbo at 1000 kph meets rock at 200 kph,....I reckon it might put more than just a dent in the Jumbo skin !!!
I reckon



APOD: 2006 November 19 - The Car, the Hole, and the Peekskill Meteorite

And another

http://www.buzzfeed.com/austinhunt/a...aught-on-video
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Old 13th Jul 2014, 01:52
  #50 (permalink)  
 
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That meteor vs parachutist was finally thought to be a rock that had been stuck in there since the last landing and dropped out again after the chute opened.
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Old 13th Jul 2014, 02:14
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CS, I'm afraid that suggestion would have been tongue in cheek.
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Old 13th Jul 2014, 23:20
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Biggish meteorite down in Cape York some years ago left a vapour trail and a sonic boom. So said the mustering cowboy. Or was it his horse having a stomach rumble?
For an object to do that there must have been a sizeable piece left to interact with the atmosphere.
Altho folk hunted along the noted line of fall, nothing found. Probably ended up in the Gulf or West Irian or ???
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Old 16th Jul 2014, 11:35
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TV 4 us

ABC Catalyst 8pm Thursday About Meteorites
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Old 16th Jul 2014, 11:53
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Safety last.......

A couple of punters who have joined the meteor club;


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Old 16th Jul 2014, 13:16
  #55 (permalink)  
Man Bilong Balus long PNG
 
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Ah yes, Cactusjack; Wonder how much her Lawyers are demanding? And from whom?
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Old 16th Jul 2014, 17:10
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I've heard that "sizzle" on multiple occasions watching multiple meteoroids burn up. It really does sound exactly like a sizzle...
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