On 10-SEP-08 at 14:21 UTC the European GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite is scheduled for launch from Plesetsk. Insertion is into a Sun-synchronous orbit of 285 km, 96.7 inclination and 18:00 LST ascending node. The following elset is based on the planned insertion state vector: GOCE Sep 1 0 08254.66082176 0.00000000 00000-0 40000-3 0 5 2 0 96.6982 260.0457 0000009 323.1730 86.6685 15.96874968 6 This is a dawn-dusk orbit essentially following the terminator. Visibility is basically in whatever hemisphere has winter. The first chance to visually observe GOCE would be in South Africa at about 17:00 UT, 10-SEP-08, some two and a half hours after launch. 5 meters long but with a cross section of just 1 m2 GOCE is aerodynamically shaped to reduce drag. During its science phase an ion engine will exactly compensate for drag so that we will get a low 270 km orbit with a zero drag coefficient! The Sun-facing side of GOCE is covered with solar cells and two of those sections (inclined downwards by 22.5 and 67.5 degrees) have the potential to cause bright flares - just how bright remains to be seen. Such a flare might be visible at 18:06 UT, 10-SEP-08 in Invercargill, New Zealand and between 19:31 and 19:35 along a line between Rockhampton and Launceston, Australia, but the attitude of GOCE will not yet be in fine pointing mode so it's rather chancy. By 11-SEP-08 the attitude should be stable and I would expect flares at 17:05 UT to the East of Cape Town, South Africa. On consecutive days GOCE passes will be at almost the same time but the line where the flares can be seen shifts to the West by about 70 - 80 km compared to the previous day. A (local) evening flare might be expected in Brisbane on 13-SEP but I shouldn't get ahead of the time and rather wait for the actual launch to take place. If anybody down under wants to try looking for GOCE flares feel free to contact me and I'll try to come up with a more specific forecast for your location. Note: Pictures of GOCE in publications and on the web usually show the solar panel side pointing toward the right of the flight pass which would have been the case if they were to launch it into a 6:00 LST orbit. But because the launch got delayed from May to September they decided on a 18:00 LST ascending node instead to avoid an eclipse period early on in the flight. As a result the Sun-facing side of GOCE will be to the left of the direction of flight. Gerhard HOLTKAMP Darmstadt, Germany ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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