1. Ascent Trajectory and Look Angles The ascent trajectory and look angles are primarily of interest to observers near the east coast of North America, interested in observing the shuttle during its ascent to orbit. Since STS 128 will be launched at night, it will be readily visible, weather permitting. I have produced an MS Excel spreadsheet to compute azimuth, elevation, R.A. and Dec, and an indication whether the shuttle is in sunlight, or the umbra or penumbra of Earth's shadow, during STS 128's ascent to orbit on its mission to ISS: http://satobs.org/seesat_ref/Shuttle/STS_128_Ascent_Trajectory_to_ISS.xls To use, enter your observation site co-ordinates and the date and time of lift-off, in the specially labelled cells (those with red coloured font). The spreadsheet is set up for STS 128's scheduled launch on 2009 Aug 29 at 03:59:39 UTC, as seen from Washington, D.C. I obtained the trajectory data from The CBS News Space Reporter's Handbook, by William Harwood: http://www.cbsnews.com/network/news/space/downloads.html Scroll down to the SpaceCalc section, and see file SpaceCalcPC_128.zip for PC or SpaceCalcMac_128.zip for Mac. 2. MECO TLE The MECO (main engine cut-off) TLE (2-line elements) are primarily of interest to observers in Europe, interested in observing the shuttle minutes after it reaches orbit, trailed a short distance by its external tank. Tonight's launch will be visible late in morning twilight, from at least France and the U.K., and almost certainly from other countries in the area. For pre-launch TLEs (2-line elements), I normally recommend using NASA's web page: http://spaceflight1.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orb it/SHUTTLE/SVPOST.html However, beware that on this web page, the MECO elset, aka Coasting Arc #1, always is totally erroneous. NASA's conversion from state vector to TLE is set up to propagate the MECO elset to the next ascending node, even though the orbit will have been circularized well before then. The problem is exacerbated by the unrealistic treatment of orbital decay for this case. Here is an alternative MECO TLE, computed from NASA's pre-launch state vector, using Ken Ernandes' VEC2TLE. It is valid until the circularization burn at 04:38:15 UTC: STS 128 MECO 58 X 233 km 1 99128U 09241.17370370 .01000000 00000-0 48348-6 0 00 2 99128 51.6419 292.6658 0133919 349.7477 68.1000 16.47936574 09 VEC2TLE is available here: http://www.mindspring.com/~n2wwd/html/state_vectors.html Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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