> Date: Mon, 01 Dec 97 15:41:29 PST > From: Craig Cholar <3432P@VM1.CC.NPS.NAVY.MIL> > Subject: Tumbling debris object 07013, 73-086D > To: SeeSat-L@cds.plasma.mpe-garching.mpg.de > [ ... ] > For newcomers, RCS is the Radar Cross Section, in square meters. It > supposedly gives a rough idea how large an object is, but it can be > deceiving. [ ... ] Large objects that are poor radar reflectors can > generate low RCS values, but still be visually observed. Something to keep in mind with respect to RCS is that it's frequency (wavelength) dependent. One possible explanation for some variations in RCS values could be that they were estimated for or measured at different radar frequencies. There are also uncertainties arising from factors such as atmospheric conditions and orientation of the object. The variation in reported RCS values doesn't surprise me at all. And as you all know :-) the visible spectrum is much higher frequency than RF. How well an object reflects radiation at thousands of megahertz (RF) doesn't really tell you all that much about how well it reflects radiation at *millions* of thousands of megahertz (visible). E.g., a hundred square meter RCS object with a rough flat-black surface may pop up on a radar like a shining beacon, but it sure isn't going to reflect much light back to your eyeball. ;-) --Sue (worden@uts.cc.utexas.edu)