USA-125/90028 is a second-generation SDS satellite. It is a spin-stabilised design with a de-spun aerial array. Another piece of evidence that the upcoming NROL-24 is a replacement for this satellite comes from the fact that the de-spin mechanism of 90028 seems to have been turned off quite recently. The array is currently (2007 Dec 7, 16:00 UTC) rotating once every 19.8s. If it follows the lead of 90004 and 90020, friction will cause it to spin up and match the body with a rotation period near 5s. 90004 and 90020 each reportedly show visual variability with a 5s component in their light curves. 90028 may join them in this. The evidence for the spin-up comes from radio observation. It was originally reported by Greg Roberts of South Africa 2007 Dec 7 and I confirmed it from the UK thanks to Greg's timely 'heads-up'. Bob Christy Lincoln, UK 53.2233 deg North 0.6004 deg West Height 59m No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.16.17/1177 - Release Date: 07/12/2007 13:11 ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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