NROL-28 is scheduled for launch from VAFB into a Molniya orbit on 2008 Feb 29, during a launch period from 08:00 to 12:00 UTC. http://www.spaceflightnow.com/tracking/index.html This will be VAFB's first launch of the Atlas V, specifically, an Atlas V-411, which I estimate can place about 5,200 kg into a Molniya orbit from VAFB. I estimate that the mass of NROL-28 is between 4200 kg and 4900 kg. The U.S. has used Molniya orbits since the early 1970's for communications and SIGINT (signals intelligence) satellites. I am confident that the payload is identical to that of USA 184 (aka NROL-22, 06027A / 29249), launched on 2006 June 27. I believe that the NRO primary payload is more likely SIGINT than communications. It is host to two secondary payloads, which will remain permanently attached: the USAF's SBIRS HEO-2 sensor, used to detect and track missile launches using an infra red sensor; and TWINS-B, a small NASA magnetospheric research package. My guess is that the actual launch window may be between about 10:30 and 11:30 UTC; the following estimated elements are based on launch at 11:00 UTC. I will post revisions once the actual launch time has been made public, typically a day or two prior to launch. SECO1 193 X 2215 km 1 71001U 08000A 08060.46831020 .00000000 00000-0 00000-0 0 08 2 71001 62.5000 41.3248 1333700 180.0000 0.0000 13.14740000 02 The SECO1 elset is valid from about T+00:14:22 to T+00:40:12. SECO2 1117 X 37642 km 1 71001U 08000A 08060.72172687 .00000000 00000-0 00000-0 0 04 2 71001 62.4000 41.2865 7090000 266.5070 180.0000 2.10000000 03 The SECO2 elset is valid beginning at about T+00:43:34. These elements are based upon the launch of USA 184, which employed a Delta IV 4,2. The performance of Atlas V-411 is roughly similar, but it may employ somewhat different SECO1 and SECO2 orbits, so the elements should be considered more approximate than usual. The night-launch will afford good visibility of the ascent from the U.S. southwest coast and adjacent areas. The SECO2 orbit appears to be well placed for visual observation from at least Europe and North America. Its standard visual magnitude should be similar to that of USA 184, 3.5 +/- 1.5 (1000 km range, 90 deg phase-angle). At mid-northern latitudes, it may reach mag 8, under the most favourable conditions of range and illumination. At apogee it will be about mag 11. http://satobs.org/seesat_ref/misc/06027A_std_mag.pdf Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sun Feb 24 2008 - 16:26:54 UTC