(meteorobs) "Corkscrew Meteor" on Space.com Image of the Day 7thJan

[Robert McNaught]

Over the course of ten years, I examined several thousand U.K. Schmidt
negatives, systematically searching for asteroids and comets.  These
photos have a resolution of around 1 arcsecond.  Numerous meteors were 
recorded, but none had anything other than a straight path, other than a
few that fragmented and dispersed at a narrow angle.

There was a period when a drive oscillation would be evident in RA trailing
in the stars and as oscillations in satellites that crossed the six
degree field (sinusoidal, or saw tooth depending on the angle of motion of 
the satellite).  Wind vibration (any vibration) could have the same effect.

Probably the most unusual thing I saw was the asymmetric brightness profile
of some satellites that were rotating and displayed brightness variations.
I came across several examples of trails where the bright spot would start
on one edge of the trail and migrate across to the other, later reappearing 
on the first side for the next brightness maximum.  The telescope was 
clearly *imaging* the satellite and recording the actual rotation as the 
more highly reflective region was rotating from one side to the other.  This
gave the impression of a screw, rather than a corkscrew.  With a corkscrew,
you can see a complete spiral, but with a screw you only see the diagonal
path of the thread from one side to the other, the return being hidden on
the far side.  The satellite need only be a few metres across, depending on
the distance, for this to be possible.

Cheers, Rob