Forgot to mention that information from Marco Langboek was used too. Sorry. Jon. 2017-04-30 11:30 GMT+02:00 Jon . <jonmikelk_at_gmail.com>: > Hello all, > > Using the information that Ted and Cees published on this thread I've > tried to build an scenario where all these things can concur. > > After some problems trying to build a Molniya orbit using this, reached > the conclusion that a LEO orbit is more probable. This does not discard a > Molniya orbit mission. > > Using the NOTAMs and Maritime Restrictions, plus the few available data > about this mission reached the following TLE, assuming launch at 11:15 UTC > (launch was delayed 15 minutes while writing the mail): > > NROL-71 scenario #1 858 X 858 km > 1 70099U 17500B 17120.67709491 0.00000000 00000-0 00000+0 0 04 > 2 70099 50.0000 280.8604 0000010 73.6430 274.4981 14.10600000 01 > > The 850 Km height is consistent with the time, location and the track of > the launch and de-orbit restriction and can explain the use of ion-based > satellite bus on a near zero drag enviroment. > > It's possible that other orbital solutions can match the data pointed by > Ted and Cees. > > If this orbit is near of reality, observers from south hemisphere would > have good dawn passes. > > > Jon. > > > 2017-04-30 10:44 GMT+02:00 C. Bassa via Seesat-l <seesat-l_at_satobs.org>: > >> The intended orbit for the NROL-76 mission, slated for launch on a >> Falcon 9 between 11:00 and 13:00UT, today remains a mystery. >> >> These are the facts that we can consider known: >> * the launch hazard area is consistent with a 50 deg inclination >> * the de-orbit hazard ara is also consistent with a 50 deg inclination >> * the launch window is not planar (the April 16 launch date also had >> 11:00 to 13:00UT) >> * the de-orbit hazard area is valid from 03h38m to 6h15m after launch >> >> All these facts can be considered peculiar. To my knowledge, no NRO >> launches have targeted orbits inclined at 50 deg, and all launches, >> except perhaps missions to GSO, had planar windows. >> >> Furthermore, the long time between launch and de-orbit is not >> compatible with previous Falcon 9 launches. On recent CRS missions (8, >> 9 and 10), the de-orbit area was valid from about 00h26m to 01h19m >> after launch, indicating the second stage was de-orbited before it >> completed a full orbit, with the impact point South West of >> Australia. The Orbcomm OG-2 mission, targeting a 47deg orbit, had a >> similar location and time range for the de-orbit area. >> >> During the Jason 3 and Iridium NEXT missions, the second stage >> performed a circularization burn at 00h55m (Jason 3; >> 1296kmx1321km_at_66deg) and 00h52m (Iridium NEXT; 618kmx627km_at_87deg) >> after launch. Here, the de-orbit areas were valid between >> 01h06m-02h07m and 01h52m-02h48m after launch, respectively. >> >> If NROL-76 targets LEO, why de-orbit the second stage only after about >> 2.5 orbits? >> >> I wonder if instead NROL-76 targets some sort of MEO/HEO orbit. If so, >> it may be expected that perigee is located in the South to allow the >> second stage to be de-orbited off the coast of Africa. >> >> Regardless of the target orbit, it'll be an interesting challenge to >> locate the NROL-76 payload. >> >> Regards, >> Cees >> _______________________________________________ >> Seesat-l mailing list >> http://mailman.satobs.org/mailman/listinfo/seesat-l >> > > > > -- > Jon, COSPAR 6242, 42.9453, -2.82839, 623m, Bitoriano, Basque Country. > -- Jon, COSPAR 6242, 42.9453, -2.82839, 623m, Bitoriano, Basque Country. _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Sun Apr 30 2017 - 04:35:36 UTC
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