NROL-26 search elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Mon Jan 12 2009 - 21:45:50 UTC

  • Next message: Brad Young: "BY PPAS to Jan 12"

    The launch of NROL-26 is scheduled for 2009 Jan 14 at 00:49 UTC; the launch
    window is about four hours:
    
    http://www.spaceflightnow.com/delta/d337/status.html
    
    The primary observable event of interest would be the propellant dump after
    insertion into GEO, which would appear as a bright comet.
    
    The following approximate search elsets and discussion assume launch at 00:49
    UTC.
    
    LEO coast                                                258 X 272 km
    1 70501U          09014.05150463  .00000000  00000-0  00000-0 0    04
    2 70501  27.3000 303.8700 0010000 183.0000 359.3500 16.05000000    08
    
    GTO burn at 1st descending node                        268 X 36408 km
    1 70502U          09014.25990509  .00000000  00000-0  00000-0 0    00
    2 70502  27.3000 303.8000 7311000 182.9000 167.5000  2.23480000    02
    
    GTO burn at 1st ascending node                         268 X 36408 km
    1 70503U          09014.08219168  .00000000  00000-0  00000-0 0    07
    2 70503  27.3000 303.6000 7311000   3.4000 359.6000  2.23480000    02
    
    The burn from the LEO coast orbit to GTO could occur at the first descending
    node or at the first ascending node.
    
    1. GTO at first descending node
    
    In this scenario, the launch vehicle would manoeuvre from the 70501 orbit to the
    70502 orbit at about 01:13:40 UTC, while passing through the first descending
    node (over the Atlantic Ocean, near 8 deg W).
    
    Orbit 70502 would reach apogee at about 06:36 UTC, near 93 deg E, but the
    circularization manoeuvre likely would begin as much as 10 min earlier, and last
    about 3 minutes.
    
    
    2. GTO at first ascending node
    
    In this scenario, the launch vehicle would manoeuvre from the 70501 orbit to the
    70503 orbit at about 01:58:20 UTC, while passing through the first ascending
    node (over the Pacific Ocean near 161 deg E).
    
    Orbit 70503 would reach apogee at about 07:21 UTC, near 97 deg W, but the
    circularization manoeuvre likely would begin as much as 10 min earlier, and last
    about 3 minutes.
    
    
    3. CCAM and Propellant Dump
    
    About 10 min after the GEO circularization manoeuvre, the now separated 2nd
    stage would perform the CCAM (contamination and collision avoidance manoeuvre),
    followed shortly by the propellant dump.
    
    
    4. Observing Opportunities
    
    From the ground, propellant dumps appear like bright comets.
    
    Eastern hemisphere observers should determine whether or not orbit 70502 will be
    visible between about 06:20 UTC and 07:10 UTC. It seems likely to be obscured by
    daylight, but I have not made a thorough evaluation.
    
    Western hemisphere observers should determine whether or not orbit 70503 will be
    visible between about 07:10 UTC and 08:00 UTC. It appears that North and South
    American observers would have good visibility, but I have not made a thorough
    evaluation.
    
    Ted Molczan
    
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