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 _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Sun Apr 16 2017 - 01:56:45 UTC
This archive was generated by hypermail 2.3.0 : Sun Apr 16 2017 - 06:56:46 UTC