Satgen 9 Sorting out the UFO's QRMing Oscar 13 on 435.974 MHz There is no need to waste effort puzzling over the orbital periods of these birds. Consider the following individual closest approach times:- 17 May 1424 1522 1607 1710 18 May 1408 1541 1554 1726 19 May 1437 1514 1625 1658 20 May 1446 1507 1630 1656 These are a sample 3.5 hour selection which as printed tell us very little But if plotted on graph paper as shown in the crude example below, a very positive pattern emerges, whereby every occurrence of a satellite can either be accomodated on an A line which gets 26 minutes earlier each successive day, or a B line which gets 30 minutes latter each day. Telling us one sat completes a set of orbits in 1440-26 minute for a best fit of 14 orbits of about 101 min period, while the other sat takes 1470 minutes for 14 orbits each of 105 min period approx. This plot is based on a method used by the Kettering Group. Date 15 Time 16 utc 17 :.........:.........:.........:..... 17:...A.....:...B.....:A........:.B... 18:B........:......A.B:.........:...A. 19:.....B...:.A.......:...B.....A..... 20:.......A.:B........:....A...B:..... Only a very brief chart is shown here , to allow it to fit those restricted to 40 column printers .In practise the horizontal scale used is 0700 to 2100 ut,with scaling 1 hour = 2 cms, and vertical scaling of 1 day = 1 cm. More later in Satgen, on this subject of simple orbit analysis, plus a full review before long, in an RSGB Space Handbook. Shorts.... PACKSATS . Launch delayed to Nov 89 earliest because French do not want to launch prime payload Spot 2, until existing Spot 1 begins to show signs of old age. Uosat DE also goes on this mission. RS 12/13 is due to launch in next 3 weeks. It carries similar transponders to present RS10/11. Listen 29.408 , 29.454, 29.458, and 29.504 for sat signing RS12 or RS13. MIR is reported to have a battery power supply problem. Rumour says special repair crew is being trained to go up and deal with problem One report suggests it will be Dzanibekov and Savinyk who rescued Salyut 7 in 85. But Dzanibekov is now a General and Savinyk is a University administrator. So that is unlikely. Lots of traffic coming down from Mir on Spread Spectrum 166.122 MHz when it is east of UK. SALYUT Whatever caused frequency jump of beacon has stabilized.19.956 MHz beacon has been audible in UK from South Pacific 1000 ut and Indian Ocean around 2030 ut. Listen for FSK slow dot dash sequence followed by a reset dot ripple transmission. Salyut makes 6 passes near UK 1300 to 2100 today STUDENTS interested in Space courses and research opportunities may find The Space Science and Technology Directory useful. Ring 01-873-900 73 de GM4IHJ 31 May 89.