I never believed the 100-meter diameter estimates. They seemed to be extrapolations based upon assumed manufacturing capabilities, but they were never attached to an assessment of technical requirements. Simply put: did any antenna need to be that big? Nobody answered that.
Has anyone ever used the observed magnitudes of Orion satellites to estimate the diameter of the primary dish?I've read that they are a few magnitudes brighter than "typical" GEO satellites: typically +8.
You could only estimate the diameter if you knew the material and the rough pointing of the reflector. That's a lot of assumptions.
Quote from: gosnold on 02/14/2018 08:37 pmYou could only estimate the diameter if you knew the material and the rough pointing of the reflector. That's a lot of assumptions....Another, more exotic idea: Observe a stellar occultation. Determining the occultation chord length would place a lower bound on the dish diameter....
Ok, I'll "bite". From hearsay etc., we "know" that satellites with large antennas have been constructed/launched for the past 20+ years, but there is no official indication on the antenna diameters (i.e. if they measure several 10s of meters, or the alleged 100 m).
There are relatively inexpensive CMOS cameras available, which are suitable for night time observing. Still, a decent size telescope would be required to detect a (faint) star at sufficient signal-to-noise in individual 10ms exposures to get a good light curve of such an occultation event. You'd probably want to go down to stars with visual magnitudes around 12 in the visual, and use a telescope with at least 15(?) inch diameter to have a decent chance of detecting one event in the course of an observing night.
Good analysis! Note though that you'd want the occultation to occur when the satellite is in the Earth's shadow, as otherwise the 8 mag satellite will outshine a 12th mag star by about a factor of 40.