Zuma is scheduled for launch from Cape Canaveral on a Falcon 9 v1.2 on 2017 Nov 17, during a two hour launch period that opens at 01:00 UTC. I have not done much research on this launch. There has been considerable discussion on NasaSpaceflight.com, which I have read through. The launch was procured by Northrop Grumman on behalf on an unspecified U.S. government customer. The NRO reportedly has denied ownership, but in my opinion that does not preclude a mission on behalf of the NGA or NSA. Spaceflight Now will cover the launch: https://spaceflightnow.com/2017/11/15/falcon-9-zuma-mission-status-center/ The ascent NOTAM suggests a trajectory very similar to that of NROL-76, which launched USA 276 (17022A / 42689) into a 50 deg orbit. USA 276 subsequently made a number of close fly-bys of ISS. The second stage de-orbit NOTAMs is consistent with a quasi-50 deg orbit, with de-orbit occurring about 3.5 h after launch. Marco Langbroek has posted 50 deg inclination TLEs for altitudes of 300 km, 400 km and 500 km, at 30 min. intervals during the launch period: http://satobs.org/seesat/Nov-2017/0059.html Closer analysis of the stage 2 de-orbit NOTAM, reveals that at de-orbit the inclination is closer to 52 deg, and the RAAN is about 8 deg west of that of the 50 deg orbit derived from USA 276. This does not invalidate the Zuma 50 deg orbit hypothesis. It would be well within the performance of stage 2 to increase its inclination by 2 deg and decrease RAAN by 8 deg for de-orbit, which represents a 6.5 deg plane change. The manoeuvre could be performed near 48 deg N descending or 48 deg S ascending, and would require delta-V of 0.114 times orbital velocity. However, different mission profiles are possible. One possibility would be for Zuma to be deployed into a 52 deg inclination orbit of 1000 km altitude, with RAAN about 2.4 degrees east of the 50 deg orbit derived from USA 276. The higher orbit would delay the de-orbit of stage 2 sufficiently to allow the de-orbit zone to rotate directly under the trajectory. The mission could be begin with a 300 km parking orbit: Parking orbit 292 X 313 km 1 70000U 17999A 17321.04166671 .00011340 00000-0 15763-3 0 04 2 70000 52.0000 327.1356 0015627 353.6173 19.7000 15.90000000 04 Following an apogee raising manoeuvre at 01:20 UTC, and a circularization burn at 02:09:20 UTC, Zuma would be deployed into the following orbit: Zuma 998 X 999 km 1 70000U 17999A 17321.08981482 .00011340 00000-0 15763-3 0 03 2 70000 52.0000 326.9128 0001000 95.1090 179.9200 13.70400000 05 Stage 2 de-orbit at 03:00:20 UTC would result in the following orbit, which would re-enter at about 03:40 UTC, on a track that follows close to the centre-line of the de-orbit NOTAM. Stage 2 de-orbit 14 X 999 km 1 70000U 17999A 17321.12523149 .00000000 00000-0 00000-0 0 06 2 70000 52.0000 326.7822 0715000 270.0000 179.8000 15.20000000 01 The above is only one of many possible solutions. The inclination and RAAN of the parking orbit determine the altitude of the final orbit of Zuma that would we required for the second stage to align with the de-orbit NOTAM zone, which could be well over 1000 km. Some scenario's would also require stage 2 to make a small plane change. I have no idea what will happen. It would be prudent to begin searches using the 50 deg orbits that Marco posted, but be prepared to consider orbits a bit higher in inclination, and quite a bit higher in altitude. Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Thu Nov 16 2017 - 01:03:25 UTC
This archive was generated by hypermail 2.3.0 : Thu Nov 16 2017 - 07:03:26 UTC