More on the S&T photo

Matson, Robert (ROBERT.D.MATSON@saic.com)
Thu, 7 Oct 1999 10:32:27 -0700

Hi All,

Bill Bard brought up the point that the two N-S tracks
in the S&T photo did not necessarily have to occur at
the same time, but could have occurred at any point
during the 40-minute exposure.  While I thought this
point was understood (that the two tracks do not have
to be linked, just as the 4 GEO tracks aren't), others
might have gotten that impression based on the discussion.

But the point here, folks, is probability.  For a satellite
to fly exactly north-south requires a very precise choice
of inclination *AND* altitude.  In other words, the
satellite inclination that produces an apparent N-S
trajectory is a function of altitude.  But to make matters
worse it is ALSO a function of the viewer's latitude.

To have all three of these factors converge during a
40-minute exposure of a narrow field of view is pretty
remarkable, particularly considering that there are no
other tracks at skew angles.  But to have a SECOND track
parallel to the first (and extremely close) -- the odds
against it are truly astronomical (no pun intended).  In
fact, they are zero (unless someone is flying a secret
tethered pair of bright satellites in a nearly polar
orbit that somehow has evaded all of us for more than
7 months).

Of course, that's what makes this problem so interesting --
the track doesn't *look* like what a plane would leave on
film, yet it can scarcely be anything else.  Someone did
bring up the possibility of two military planes, either
flying in formation or engaged in in-flight refueling, but
this still requires a solitary, non-blinking light on each
plane.  (Or blinks that are infrequent enough to evade the
2-1/4-degree FOV of the exposure.)

On a final note, Dale Ireland said he mentioned the non-
satellite nature of the N-S tracks to S&T magazine, to
which he apparently got a glib response admonishing that
"we don't know everything that's up there."  While that
is certainly true, it is totally irrelevant.  We *DO*
know of every artificial satellite that ~could~ have
left tracks like those in the photo on the date in
question.  None exist.  In all seriousness, my response
to S&T would be, "We are the experts.  If we say it
doesn't exist -- it doesn't."

Cheers,
Rob