Re: Mystery object with 31-day orbital period

From: Jonathan McDowell (
Date: Mon Oct 26 2009 - 22:50:58 UTC

  • Next message: Tony Beresford: "Re: Mystery object with 31-day orbital period"

    The high eccentricity makes it clear that this object was associated
    with a lunar transfer mission of some kind. The period is higher
    than for most lunar mission objects but not unheard of; for example
    some of the Agena rockets for the Ranger missions of the 1960s were
    in orbits very like this. (We can assume that the original perigee was
    much lower - say 200 km or so - and has been perturbed up to its present
    circa 50000 km; that's what inevitably happens to such orbits). 
    Given the large perturbations on such an object over the years, it's
    going to be hard to identify with a specific launch.
    An example: Centaur AC-6, a mission testing parking orbit restart towards
    the Moon,  ended up in a 166 x 815042 km x 28.6 deg orbit.
    Exercise: figure out whether it reentred on first orbit, or ended up 
    in an orbit like the one you observe, or got perturbed to solar orbit.
    Not so easy.
     - Jonathan McDowell
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