Re: Possible re-entry observation

From: Dwayne Crow (
Date: Tue Mar 12 2002 - 19:21:59 EST

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    Thanks for the reply... You're probably right about it being aircraft.  Now
    that you mention it, they were in the general direction of the DFW airport
    (about 20 miles away) and you'll often see that many planes in one view at
    night when you can see their strobe lights.
    I'm going to watch the sunset the next clear day we have and see if we can
    reproduce the effect for her curiousity...
    ----- Original Message -----
    From: "Alan Pickup" <>
    To: "Dwayne Crow" <>
    Cc: <>
    Sent: Monday, March 11, 2002 2:04 PM
    Subject: Re: Possible re-entry observation
    > Dwayne Crow reports...
    > >On Monday March 4, 2002 my wife observed what sounds to me like a
    > >satellite reentry and I'm hoping some of you might have the expertise to
    > >help us determine what it was she saw.
    > >
    > >Observation occurred in Plano, Texas.  She was driving west at 6:35 pm
    > >time (00:35 UTC which would be 03/05/2002).  The sun had just set below
    > >horizon and she was admiring the pink color in the western sky when she
    > >noticed 8 fireballs in the sky.  From her description, they were spread
    > >an irregular pattern over an area with about a 10 degree diameter, with
    > >lowest one about 25 degrees over the western horizon.  Each of the
    > >looked like a long, streaming fireball, and one of them had a
    > >smoke trail.  She pulled over to watch them and estimates that they were
    > >visible for about 5 minutes, all disappearing at about the same time.
    > >said they were moving extremely slowly, almost imperceptibly from left to
    > >right (northerly).   I occasionally drag her out of the house to see the
    > >or something, so she's familiar with the speed that you normally see
    > >satellites moving, and she was amazed at how slow these objects were.  I
    > >asked her how far they moved from left to right during the entire 5
    > >and she couldn't say, it was such a small amount.
    > >
    > >First question:  Does this sound like a satellite re-entry?
    > No. There is no way that any re-entry fireball (let alone eight of them)
    > could be visible in the same area of sky for about 5 minutes. While a
    > re-entry might be observable for 90 seconds, or perhaps even longer, on
    > an overhead transit from horizon to horizon, the only way you might see
    > it for much longer would be by viewing it from an aircraft at high
    > altitude, or from orbit. And no re-entry could appear to move "extremely
    > slowly, almost imperceptibly" since the near-orbital velocity is
    > essential to generate the frictional heating that leads to the fireball.
    > On the other hand, I see several reports (and sometimes photos too) each
    > year of slow-moving "fireballs" in the western sky at dusk that are
    > undoubtedly due to aircraft and their short-lived condensation trails
    > being illuminated by the Sun, although the latter may be below the
    > observer's horizon. In such a circumstance, the trail can shine brightly
    > by forward scattering while, because of its distance and altitude, the
    > aircraft itself is inaudible and, unless it glints in the sunlight,
    > might be invisible too. The darkening sky may also increase the contrast
    > and makes the observation even more startling. The disappearance is most
    > likely to be due to the sunlight disappearing as seen from the aircraft,
    > either because it has set or passed behind a cloud, or it might be due
    > to a change in the local atmospheric conditions that give rise to the
    > trail or (possible the same thing) the aircraft climbing above or
    > falling below the critical altitude.
    > >OIG's "Query decay by date" returned one object for March 4 and four on
    > >March 5.    Can anyone refer me to some software that would let me plug
    > >the tle's for these 5 objects to see if any of them coincide with the
    > >time/location of the observation?
    > A first pass might be to run the elsets through a prediction program
    > that gives you a ground track for the period in question - Mike McCants'
    > LATLONG will do that, but there are several others. In most cases you
    > will find that the orbit could pass nowhere near the observing location
    > (sometimes even the continent!) at the time in question, which rules out
    > any possibility of that object being responsible. Surviving candidate
    > decayers need closer analyses, including more detailed prediction and
    > comparison with the direction and altitude of the observation
    > Alan
    > --
    > Alan Pickup / COSPAR 2707:  55.8968N   3.1989W   +208m   (WGS84 datum)
    > Edinburgh  / SatEvo & elsets:
    > Scotland  / Decay Watch:
    >           *
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