Re: Mystery object with 31-day orbital period

From: Tony Beresford (
Date: Tue Oct 27 2009 - 00:32:46 UTC

  • Next message: Jonathan McDowell: "Re: Mystery object with 31-day orbital period"

    At 09:20 AM 27/10/2009, Jonathan McDowell wrote:
    >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.
    Jonathon, quoting from the JSR report about the launch of the
    Spitzer telescope.
     >SIRTF's Delta second stage was also in a hyperbolic Earth orbit  at
     >spacecraft separation. However, two further burns at 0642 UTC and 0647
     >UTC are reported to have reduced the velocity enough to make the orbit
     >elliptical again, with a negative perigee. The stage will coast out to a
     >high apogee and then fall back into the Pacific Ocean. If anyone can
     >provide details of the stage's trajectory I'd appreciate it.
    Did you get anymore information? Could this be the mistery object?
    Tony Beresford
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