FWD: NOSS satellites and magnitudes

Philip Chien (kc4yer@amsat.org)
Mon, 18 Mar 1996 04:15:38 -0400

Yeah I know it's a really old message, but I'm finally getting around to
cleaning out my In box ...

Bart De Pontieu <BDP@MPEPL> said:

>"Last Tuesday night (Feb 20) between 10:10 and 10:15pm CST (Feb.21/96 04:10
>UT) a number of people observed what appeared to be three satellites moving
>in unison.  They were moving from the NW toward the zenith.  Two were bright
> - the brightnesss changed as we watched but peaked in the negative
>magnitudes (similar to Sirius).  As we watched they faded from view -
>presumably due to the Earth's shadow."
>
>Running Quicksat with some Molczan elements (960217) almost certainly pins
>them as the NOSS 2-1 cluster (bodies B, C and D; NORAD numbers 20682, 20691,
>20692).  Time, direction and entering of shadow all match the Quicksat
>predicition.  What is interesting though is the magnitude.  I have observed
>a number of NOSS clusters and have always (but one exception) seen them as
>mag. 5 or 6 objects.  The one exception was about a year ago when I saw them
>at about mag. 2 at and extremely low altitude (about 20 degrees).  To be as
>bright as mag.2 at such a large line of sight distance implies they must
>have something rather large for a reflecting surface.
>
>I knew that the NOSS clusters were classified military satellites (White
>Cloud) that used radio interferometry for target acquisition.  At least this
>is what I assumed based on what I could find.

The very early NOSS spacecraft were launched as trios on single stage Atlas
launch vehicles.  Since the Atlas is a medium class vehicle with a fairly
small fairing the satellite have to be fairly small.  They have been
reported to brighten up on occasion.  According to a translated Russian
document I've seen the satellites have a long extended boom with an end
mass.  My guess would be that it would be for the purpose of making the
spacecrafts gravity graident stabilized.

The later NOSS, especially the series you mentioned (NOSS 2-1) were
launched on Titan IV launch vehicles - much more powerful launch vehicle
and much larger fairing.  I don't recall which model fairing that cluster
used but it had *LOTS* of volume.  The Titan IV encapsulates the upper
stage (IUS or Centaur) with the payload within the fairing so LEO payloads
can be extremely large - as large as the shuttle's cargo bay in fact.  (not
a coincidence).  When NOSS satellites are launched on a Titan four
classified USA designations are given.  Presumably the fourth designation
is for another, possibly unrelated, satellite which is launched at the same
time.  Unless the second generation NOSS are incredibly large the other
satellite would have to be a fair size object.  The problem is that, to the
best of my knowledge, nobody has reported spotting the other payload
launched with Titan NOSS spacecraft.

Some folks have speculated that the other payload is a KH-12 (or whatever
you want to call it) but the speculation is on extremely shakey grounds
without any reasonable logic to assume that it has any basis in fact.  (the
you-know-who method of sound byting and appearing to be knowledgable on the
evening news)

In any case the second generation NOSS are certainly much brighter than the
original spacecraft, explaining your observations.




Philip Chien, Earth News - space writer and consultant  PCHIEN@IDS.NET
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