RE: Fobos-Grunt: new pieces catalogued by USSTRATCOM

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Mon Dec 05 2011 - 12:21:14 UTC

  • Next message: Peter Wakelin: "SATOBS 2011 December 05"

    USSTRATCOM has issued another TLE of 11065H / 37947, at an altitude close to decay on Dec 1. Adding this data to my
    analysis using STOAG, yields the revised estimate of A/m of about 0.029 m^2/kg, assuming Cd=2.2, and using actual space
    weather. Areal density, which is simply the inverse of A/m, was about 34 kg/m^2. If the object was 10 cm across, as very
    roughly implied by the RCS value, then its mass was roughly 0.3 kg, but please consider the cautionary information
    below.
    
    Here is the revised plot of evolution of mean altitude:
    
    http://satobs.org/seesat_ref/phsrm/11065H_orbit_evolution_v2.pdf
     
    The CAIB (Columbia Accident Investigation Board) report, "An Assessment of Potential Material Candidates for the Flight
    Day 2 Radar Object Observed during the NASA Mission STS-107", is recommended reading for anyone interested in the
    methods used to narrow down the possible identity of orbiting objects from a list of candidate objects and materials,
    based on radar and ballistic characteristics:
    
    http://www.nasa.gov/columbia/caib/PDFS/VOL3/E03.PDF
    
    It is especially important to note the comment, on pg.8, "The RCS is a complex function that depends on the SIZE, SHAPE,
    and MATERIAL COMPOSITION of the object in question, as well as the operating FREQUENCY of the radar and the ANGLE or
    orientation of the object relative to the observing radar." Without that information, it is impossible to accurately
    estimate the size of the object based on the published RCS value. For the report, the RCS of candidate objects was
    determined through laboratory measurement.
    
    Ted Molczan
    
    
    _______________________________________________
    Seesat-l mailing list
    http://mailman.satobs.org/mailman/listinfo/seesat-l
    



    This archive was generated by hypermail 2b29 : Mon Dec 05 2011 - 12:22:26 UTC