RE: NROL-76 payload speculation

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 16 Apr 2017 02:56:02 -0400
It has occurred to me that the three Boeing BSS-702SP purchased by an unnamed U.S. government agency could be a new
Molniya orbit version of the NRO's SDS satellite.

The first SDS 4 (2016-047A / 41724) was launched to GEO last July on an Atlas V 421. Its observed rate of rotation
while in GTO, 0.25 RPM, was the same as that observed of WGS 8, a known BSS-702HP satellite, which suggests that it has
the same bus. (I intend to document this finding in a post in the not too distant future.)

The last SDS launch to Molniya was SDS 3-4, in December 2007. That is a long time without a new launch. Perhaps the NRO
has decided to phase out the Molniya SDS. If not, then I would expect the launch of a new generation in time to support
the next generation of heavy electro-optical imagery reconnaissance satellites, the first of which is scheduled for
launch in Fall 2018 on NROL-71.

If the three U.S. government Boeing BSS-702SP are the Molniya version of SDS 4, then for one of them to be the payload
of NROL-76, its approximately 2,000 kg mass must fall within the range that would permit Falcon 9's first stage to RTLS
(return to launch site).

I used the following launch vehicle performance calculator for my analysis:

http://www.silverbirdastronautics.com/cgi-bin/LVPcalc.pl

If the spacecraft's orbit at separation from stage 2 had the typical operational Molniya inclination and apogee, then a
single BSS-702SP could be launched:

Launch Vehicle:             Falcon 9 v1.2 (land recovery) w/standard fairing
Launch Site:                Cape Canaveral / KSC
Destination Orbit:          39000 x 220 km, 62.5 deg
Estimated Payload:          2378 kg
95% Confidence Interval:    1771 - 3050 kg
Note: Caution: limited technical data available
Note: Possible dogleg ascent - performance impact estimated

If the spacecraft's orbit at separation from stage 2 were the same as that of SDS 3-4, then at least one, perhaps two
BSS-702SP could be launched together:

Launch Vehicle:             Falcon 9 v1.2 (land recovery) w/standard fairing
Launch Site                 Cape Canaveral / KSC
Destination Orbit:  	    16000 x 220 km, 61 deg
Estimated Payload:   	    3990 kg
95% Confidence Interval:    3234 - 4827 kg
Note: Caution: limited technical data available
Note: Possible dogleg ascent - performance impact estimated

A weakness with the Molniya SDS hypothesis, is that I cannot explain the use of BSS-702SP for Molniya SDS and BSS-702HP
for GEO SDS. For that reason, I prefer the earlier hypothesis of a GEO mission similar to PAN and CLIO, aka Nemesis 1
and 2.

The NOTAMS will enable us to distinguish between a GTO and high-inclination launch.

Ted Molczan

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Received on Sun Apr 16 2017 - 01:56:45 UTC

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