Re: Number of Objects in Orbit

From: Brian Weeden (
Date: Sun Jul 13 2008 - 18:50:35 UTC

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    That may be a factor in a small minority of cases but the vast
    majority are in the 80,000's for the reasons I stated and not any
    incompetence or laziness.  There are many reasons why it is critical
    to move all of those than can be moved into the catalog and the
    military and civilian professionals who maintain the catalog work very
    hard to make sure it happens quickly AND accurately.
    On Sun, Jul 13, 2008 at 2:32 PM, Phillip Clark
    <> wrote:
    > There is also the question of lethargy.   The objects in the "temporary
    > catalogue" - 80,000 numbers - have to be transferred manually to the public
    > catalogue, and often there is no pressing reason for the transfers to be
    > made in a timely manner.
    > Additionally, the objects don't get transferred until a stable orbit has
    > been derived, so for smaller objects or objects with high-apogee orbits this
    > can lead to additional delays in being catalogued - if it happens at all.
    > Phil Clark
    > ----- Original Message ----- From: "Brian Weeden" <>
    > To: "seesat" <>
    > Sent: Sunday, July 13, 2008 7:04 PM
    > Subject: Re: Number of Objects in Orbit
    >> The main reason is identification and a secondary is the ability to
    >> maintain the orbit.  To be placed in the catalog, an object must be
    >> tied to a specific launch event.  That's where the International
    >> designator comes from.  Those few thousand objects (17000 - total
    >> cataloged) are the ones that are tracked fairly reliably but haven't
    >> been tied to a launch.  Might have been a piece of a piece from
    >> something to broke up decades ago, or possibly something that was lost
    >> for several years.  The unit that maintains the catalog tends to take
    >> association of an object with a launch very seriously because it
    >> implies ownership by a State and perhaps liability if something were
    >> to happen involving that object.  And yes, some of those objects are
    >> the very small pieces of debris and/or ones with very erratic
    >> perturbations for which it is hard to maintain a good element set.
    >> ----
    >> Brian
    >> On Sun, Jul 13, 2008 at 1:35 PM, Gerhard HOLTKAMP
    >> <> wrote:
    >>> The latest issue of Orbital Debris Quaterly News (Volume 12, issue 3,
    >>> July
    >>> 2008) mentions in an abstract that approximately 17,000 objects are
    >>> currently
    >>> tracked in orbit by the U.S. Space Surveilance Network (USSSN) while the
    >>> Satellite Box Score on the final page shows the number of cataloged (by
    >>> USSSN) objects as 12,851 (as of 25-JUN-08). Why are there over 4000
    >>> objects
    >>> tracked but not cataloged? Are those objects which cannot be correlated
    >>> with
    >>> a particular launch?
    >>> At the same time the publicly available TLE list by Spacetrack contained
    >>> 11,556 unclassified objects while our own classfd.tle stands at about 223
    >>> objects. This makes it 1072 cataloged objects (over 8% of the total) for
    >>> which the general public does not have any orbit information. I assume
    >>> the
    >>> majority of those objects will probably be small debris pieces which are
    >>> difficult to track consistently with our visual observations.
    >>> Gerhard HOLTKAMP
    >>> Darmstadt, Germany
    >>> -------------------------------------------------------------------------
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