(meteorobs) The Hayabusa 'meteor' - a lesson for us?

[Chris Peterson]

I'd say there is no simple way to reliably distinguish space debris from a 
natural meteoroid by visual appearance of the meteor alone. Speed is an 
almost certain indicator, but speed can't be determined normally from a 
single viewpoint (unless, for example, the event is very long and nearly 
overhead).

Hayabusa, of course, was not your usual space debris, since it came from 
outside Earth orbit and therefore had a much higher velocity than any 
normal, orbiting debris would have on entry. Peekskill had a higher speed 
than Hayabusa, but it survived longer and produced a longer ground path.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: "Daniel Fischer" <dfischer at astro.uni-bonn.de>
To: <meteorobs at meteorobs.org>
Sent: Monday, June 14, 2010 4:14 AM
Subject: (meteorobs) The Hayabusa 'meteor' - a lesson for us?


>I reckon by now you've all watched the amazing video clips of the 
>disintegration
> of the Hayabusa main craft over Australia, recorded from a NASA airplane -
> http://www.youtube.com/watch?v=u-Xp_-_gLTA from one camera,
> http://www.youtube.com/watch?v=gfYA4f-AIL0 from another one - and from
> the ground (as in http://www.youtube.com/watch?v=_IAX9Hsloq4 on TV and
> http://www.youtube.com/watch?v=IPUxTSPN_bQ from a live webcast).
>
> The similarity to a major bolide event is striking, up to the color 
> phenomena,
> as has been noted by some already. Now we used to believe that - even just
> based on videos on the web - it is easy to tell a natural bolide from a
> man-made satellite reentry, with the much slower speed of the latter being
> the most important argument. Thus after the Texas bolide of 15 Feb 2009 - 
> see
> http://cosmos4u.blogspot.com/2009/02/texas-fireball-leads-to-meteorite-finds.html
> for many links - the astronomers got it right from the beginning while 
> many
> others continued to believe in some satellite-related phenomenon for days.
>
> Now ... if yesterday's Aussie fireball had surprised you, would you have
> been able to tell from the video evidence alone that this was *not* a 
> meteoroid
> burning up? Even though some of the videos look (to me, at least) 
> shockingly
> like e.g. the similarly well recorded Peekskill bolide. The latter was 
> rather
> slow in the sky, while Hayabusa came in very fast (12.2 km/s) - this may 
> explain
> a lot. But I'm still wondering whether the some *other* distinguishing 
> feature
> that would have allowed one to tell for sure that the Aussie event was a 
> reeentry.
>
> Daniel