RE: Lacrosse 2 may have been de-orbited

From: Ted Molczan (
Date: Fri Apr 01 2011 - 18:32:07 UTC

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    I now believe that Lacrosse 2 (91017A / 21147) made at a major orbit manoeuvre, probably to de-orbit, in the early hours
    of 2011 March 26 UTC.
    Pierre Neirinck reports that he observed Lacrosse 2 on Mar 25 at 20:19 UTC. It was on a near overhead pass, and reached
    magnitude 2. He was unable to identify his reference stars, so had no positional data to report. It was a no-show for
    him on March 28, but he allowed little margin for early arrival, so if it had lowered its orbit, it could have passed a
    bit before he began observing.
    Another observer has reported off-list, that Lacrosse 2 was a no-show on March 26, to a high degree of confidence.
    Earlier that day, at about 02:18 UTC, Lacrosse 2's last known orbit would have passed over the general area of the South
    Pacific into which large spacecraft are commonly de-orbited (it is located well to the east of New Zealand). The
    de-orbit manoeuvre could have occurred roughly half an orbit earlier. I have not performed a detailed analysis, so
    cannot exclude deorbit on an adjacent revolution, but it seems safe to narrow it to the early hours of March 26 UTC.
    Lacrosse 2 long ago lived up to Craig Covault's report prior to the launch of Lacrosse 1, that "the technology involved
    is highly advanced, involving a multitude of sensors designed for an especially long life." (AWST 1988 Nov 07, pg. 25).
    I have heard a rumour that Lacrosse 2 suffered some loss/degradation of function in the mid-1990s, but clearly it
    remained useful, else it would have been de-orbited long ago. To the degree that longevity is indicative of value, U.S.
    taxpayers were well-served.
    Ted Molczan
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