NROL-20: 48 ft fairing

From: Ted Molczan (seesat@rogers.com)
Date: Wed Oct 19 2005 - 08:32:16 EDT

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    The mysterious 76 ft fairing shrank yesterday to a perhaps equally mysterious 48
    ft, as reported by Spaceflight Now:
    
    http://www.spaceflightnow.com/titan/b26/status.html
    
    "The rocket is sporting an unusual 48-foot long nose cone to protect its
    clandestine National Reconnaissance Office payload during the ascent through the
    atmosphere. The fairing started as a standard 76-foot shroud but was modified to
    the shortened length, Smith said.
    
    A similar fairing was used in May 1999 when a Titan 4 launched from Vandenberg
    carrying what hobbyist sky watchers consider to be a mysterious "stealth" spy
    satellite."
    
    In order to understand the possible significance of the reported 48 ft fairing,
    it is necessary to review the different types of Titan-IV fairings that have
    flown from VAFB. What follows is my present understanding, subject to revision
    as more is learned.
    
    For a long time, it was considered that VAFB payloads employed two lengths of
    fairing: 
    
    T-IV Type  Payload   Fairing     Orbit
       403     NOSS        56 ft   63.4 deg
       403     Lacrosse    66      57 or 68 deg
       404     KeyHole     66      98 deg
    
    In 1999 came the launch of the mysterious USA 144, on a 404B Titan, to a 63.4
    deg orbit. Justin Ray, reporting for Florida Today at the time, learned
    officially that the fairing had been 50 ft long. The launch occurred in the
    middle of a foggy night (how appropriate!), and the only photo I had at the time
    inadequately revealed the fairing, so I had no easy way to verify this. 
    
    However, Phil Chien recalled that a 50 ft fairing had long been listed in the
    T-IV's promotional literature. Indeed, an early T-IV brochure, kindly provided
    by Phil, listed only a 50 ft fairing for the model 404, which was confusing,
    since the KeyHole 404 launches to that time, were thought to have employed the
    66 ft fairing.
    
    Earlier this year, I made an effort to verify the fairing length of all past
    T-IV launches for which I could locate a useable photo, which led to me this one
    of USA 144:
    
    http://www.nro.gov/graphics/launch5_99.jpg
    
    Resolution and lighting are poor, but with moderate magnification and
    brightness/contrast adjustment, I believe I can make out the boundary between
    the vehicle and adapter (aka boat tail) section of the fairing, and the boundary
    between the cylindrical and conical sections of the fairing. Likewise, I believe
    I can adequately resolve the diameter of the cylindrical section. I get a ratio
    of length to width of around 1.7, which when multiplied by the known 16.67 ft
    diameter, yields a length of 28.3 ft, which accounts for the boat tail and
    cylindrical section. The conical section cannot be measured, but all of them are
    19.86 ft long, which brings the overall length to 48 ft - pretty close to the
    reported 50 ft.
    
    In 2001 October, I learned of a new wrinkle in the story of VAFB fairings.
    Charles Vick posted to FPSPACE that the fairings of the KeyHoles launched in
    1992, 1995 and 1996 had not been 66 ft, but rather 50 ft, which sat atop a
    special 14 ft adapter he describes as a bucket, which was permanently attached
    to the 2nd stage. This brought the overall length to just over 64 ft, which
    could easily have been mistaken for a 66 ft fairing. Adding yet another wrinkle,
    Charles also pointed out that the KeyHole launched in 2001 October was the first
    to have an actual 66 ft fairing.
    
    In my exercise this year, I found that the pre-2001 KeyHole overall fairing
    length was 62 ft, close to Charles Vick's value of 64 ft. This seemed to roughly
    confirm that the fairing was 50 ft on top of a 14 ft bucket, which might explain
    the confusing claim of 50 ft in the old T-IV brochure. 
    
    Also, keeping in mind that the bucket was said to have remained attached to the
    2nd stage, it might explain why the 2nd stage of the 1996 KeyHole (96072B /
    24681) was so much brighter than other T-IV 2nd stages:
    
    http://satobs.org/seesat/Jan-1997/0003.html
    
    My analysis of launch photos also confirmed that the 2001 KeyHole launch
    employed a 66 ft fairing.
    
    So, based on my present understanding of the fairings, I interpret the news of a
    48 ft fairing on today's scheduled  404B T-IV for launch, as follows:
    
    If photographs reveal an overall length of 48 ft, then perhaps the payload is a
    Misty - the first to be targeted for one of the two standard KeyHole orbital
    planes. 
    
    If the overall length is around 62 to 64 ft, then it would appear to be a
    regular, i.e. non-stealthy KeyHole, reverting to the pre-2001 fairing length.
    
    Ted Molczan
    
    
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