NROL-38 pre-launch elements

From: Ted Molczan (
Date: Sat Jun 16 2012 - 17:57:48 UTC

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    NROL-38 is scheduled for launch from Cape Canaveral on an Atlas V-401, on 2012 Jun 18, between 12:26 UTC and 13:25 UTC. 
    The launch azimuth indicates that the final orbit will be geosynchronous. 
    The payload probably is an SDS (Satellite Data System) communications satellite. The main purpose of the SDS satellites
    is to relay data in real-time from the four KeyHole imagery intelligence satellites that operate in low Earth orbit,
    directly to NRO receiving stations in the U.S.A. The primary SDS constellation consists of two satellites in Molniya
    orbit and two in GEO. They are often augmented by older spacecraft that remain operational years after their
    replacements have been launched.
    Last year, NROL-27 launched USA 227 (11011A / 37377), which replaced SDS 3-1 (00080A / 26635) at 10 deg W; therefore, I
    expect NROL-38 to replace SDS 3-2 (01046A / 26948) at 144 W.
    I estimate the following LEO parking orbit, based on launch at window-open. The epoch corresponds to the
    first-descending node, where GTO burns typically occur:
                                                             259 X 272 km
    1 79301U          12170.53553244  .00000000  00000-0  00000-0 0    05
    2 79301  27.2800 271.6402 0010000 183.0000 359.3500 16.05000000    03
    1. GTO at first-descending node
    If the launch profile is similar to that of NROL-27, and based on the partial elements reported to the U.N., these are
    the approximate elements of the GTO, assuming the burn occurs at the first-descending node:
    Descending node GTO                                    269 X 37496 km
    1 79301U          12170.53553245  .00000000  00000-0  00000-0 0    06
    2 79301  26.5000 271.6349 7368580 182.7760 359.6507  2.16290000    00
    2. GTO at first-ascending node
    Due to the white skin of the Centaur stage of this launch, there is speculation that the launch profile will be of the
    extended coast type, in which GTO is accomplished using two large manoeuvres separated by more than an hour, resulting
    in a perigee altitude of at least several thousand kilometres and a significantly lower inclination than usual:
    I lean toward the possibility of a single GTO burn, but delayed to the first ascending node, which would occur at near
    13:35 UTC (MET 01h09m). Allowing for time to complete the burn, spacecraft separation, the Centaur's CCAM (collision and
    contamination avoidance manoeuvre) and fuel dump, could extend the Centaur's period of operation to more than 2 hours. I
    do not know whether that is sufficient to require the thermal paint.
    Here is the ascending-node burn version of the above GTO TLE:
    Ascending node GTO                                        269 X 37496
    1 79301U          12170.56621946  .00000000  00000-0  00000-0 0    03
    2 79301  26.5000 271.4034 7368580   0.0000   0.0000  2.16290000    03
    My confidence that this is an SDS launch is 90 percent; to be certain, we will have to see where it goes, and what it
    It should not be difficult for experienced observers to find the payload if/when it arrives at the 144 W SDS slot. Its
    initial operational inclination is likely to be about 5 deg.
    Greg Roberts has reported 27 brightness observations of USA 227 during 10 sessions, which indicate standard visual
    magnitude similar to the 3rd generation SDS: about magnitude 3.5 (1000km range, 90 deg phase angle). As additional
    brightness observations accumulate, it may become possible to discern whether the USA 227 and later launches employ the
    same bus as the 3rd generation. (My guess is that they are different.)
    Happy hunting!
    Ted Molczan
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