Re: Visible Tethers at 120 miles

DJLaszlo@aol.com
Fri, 16 Oct 1998 14:25:21 EDT

In a message dated 10/16/98 8:56:19 AM, prospector@sd.znet.com wrote:

<<I would like to know how we can see the -3mm tethers at distances up
to 200 km as has been demonstrated by the last tether launch. It would
seem that they are too small to see, even if they were white hot.>>

Stars and most satellites are also much too small to see with unaided eyes,
referring strictly to their angular dimensions as seen from Earth.  

The eye's retina is like a CCD in this respect:  the whole area of a given
pixel does not have to be illuminated to get a signal.  Pour enough photons
into photoreceptors and they will mediate detection of a bright spot.  To see
the tether as a line, optical aid is needed to bring up its apparent length
to within the eye's resolution threshold.

Dan Laszlo
djlaszlo@aol.com