NROL-28 search elements

From: Ted Molczan (
Date: Tue Mar 11 2008 - 20:11:56 UTC

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    NROL-28 is scheduled for launch from VAFB into a Molniya orbit on 2008 Mar 13,
    at 10:02 UTC:
    My guess is that the launch window is at least 20 min.
    This will be VAFB's first launch of the Atlas V, specifically, an Atlas V-411,
    which I estimate can place about 5,200 kg into a Molniya orbit from VAFB. I
    estimate that the mass of NROL-28 is between 4200 kg and 4900 kg. The U.S. has
    used Molniya orbits since the early 1970's for communications and SIGINT
    (signals intelligence) satellites. 
    I am confident that the payload is identical to that of USA 184 (aka NROL-22,
    06027A / 29249), launched on 2006 June 28 UTC. I believe that the NRO primary
    payload is more likely SIGINT than communications. It is host to two secondary
    payloads, which will remain permanently attached: the USAF's SBIRS HEO-2 sensor,
    used to detect and track missile launches using an infra red sensor; and
    TWINS-B, a small NASA magnetospheric research package.
    The search elements are based upon the launch of USA 184, which employed a Delta
    IV 4,2. The performance of Atlas V-411 is roughly similar, but it may employ
    somewhat different SECO1 and SECO2 orbits, so the elements should be considered
    more approximate than usual.
    Epochs are relative to launch on Mar 13, at 10:02 UTC.
    SECO1                                                   193 X 2215 km
    1 71001U          08073.42803242  .00000000  00000-0  00000-0 0    05
    2 71001  62.5000  39.5985 1333700 180.0000   0.0000 13.14740000    09
    The SECO1 elset is valid from about T+00:14:22 to T+00:40:12.
    SECO2                                                 1117 X 37642 km
    1 71001U 08000A   08073.68144909  .00000000  00000-0  00000-0 0    09
    2 71001  62.4000  39.5602 7090000 266.5070 180.0000  2.10000000    02
    The SECO2 elset is valid beginning at about T+00:43:34.
    The night-launch will afford good visibility of the ascent from the U.S.
    southwest coast and adjacent areas.
    The SECO2 orbit appears to be well placed for visual observation from at least
    Europe and North America. 
    NROL-22's standard visual magnitude should be similar to that of USA 184, 3.5
    +/- 1.5 (1000 km range, 90 deg phase-angle). At mid-northern latitudes, it may
    reach mag 8, under the most favourable conditions of range and illumination. At
    apogee it will be about mag 11.
    Ted Molczan
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