Cosmos 2293 will decay around 17.May -96 --------------------------------------------------------------------- This is the justified but unedited header and text of the root (http://algonet.se/~b_gimle/eorsat.htm) of a new tree of articles and charts about the EORSATs during operation and decay, and a comparison to photo recon satellites. The links start from the #23336 line in the home (index.htm) and decayers.htm pages. As usual with Netscape, you can follow the links before the miniature charts are completed, but if you only want to pick a few charts, you may want to disable 'Images' before you load the root page. The charts are also linked in an (almost) circular wheel, with eorsat.htm as the hub, but the order is at the moment not the same as in the following text. --------------------------------------------------------------------- Cosmos 2293 6.0 0.0 0.0 4.5 1 23336U 94072 A 96114.40186927 +.00440256 +68709-5 +53284-3 0 01787 2 23336 064.9950 067.0026 0108389 254.9591 103.9629 15.96982904083652 NASA's (USSPACECOM's?) latest 60-decay prediction (Apr.18) does not yet list this object. Cosmos 2293 is one of the Russian 'EORSAT's ( Electronic Ocean Reconnaisance Satellites ). The operational orbits of the current generation of these satellites has always been a circular orbit with Mean Motion of 15.520 anomalistic orbits per day. Usually there are two or more satellites operating at any given time, and their orbits are controlled so that they pass at about 30 minutes intervals. This is maintained with a very high precision, (See below.) unlike photo reconnaisance satellites, whose orbits are adjusted with large impulsive delta-V's, when atmospheric drag has lowered the orbit too much. Since Cosmos 2293 was commanded out of its operation orbit, about 960326, it appears to follow a normal decay curve. An earlier EORSAT that decayed normally after being brought down from the operational orbits is Cosmos 2244. Some EORSATs appear to have had their orbit correction systems running in the initial decay phase (Two-phase EORSAT decays) and, finally, some decayed so slowly that the orbit correction systems appears to have been operating during the entire decay (Slow EORSAT decays) The screen snapshot below shows Mean Motion values for EORSAT Cosmos 2293 from elsets. To EORSAT Cosmos 2293 graph. Operational EORSATs : Cosmos 2326 is still operational. The screen snapshots below shows Mean Motion values from elsets. You can see many cycles of decreasing MM, with intervals of about 12 days and amplitude of about 0.0015. This is very different from the normal operation of the KeyHoles and the Russian photo-reconnaissance spacecraft, that increase their MM by about a hundred times this amplitude by atmospheric drag over periods of nine days to many months, and then reclaim that by single (or double) rocket impulses. The smooth decreases seem to indicate a continuous low-thrust orbit correction system - but there are lots of data points between and during these periods. They could indicate inaccurate orbital elements, or a correction system that is working by small impulses - not always exact. To EORSAT Cosmos 2326 graph. See also "Novosti Kosmonavtiki" article in seesat-l/2182. Cosmos 2313 is operational, in the same orbital plane as 2326 (and 2293). To EORSAT Cosmos 2313 graph. Reconnaisance satellites : Cosmos 2320 is a typical Russian reconnaisance satellite. The size of MM adjustments vary between about 0.2 and 0.02, the intervals between 9 and 45 days ! This is very different from the normal operation of the EORSATs, that decrease their MM by about one percent of this amplitude over a period of 12 days, then quickly lose that decrease by atmospheric drag (or rocket impulses). The screen snapshot below shows Mean Motion values from elsets. To Recon sat Cosmos 2320 graph. Cosmos 2305 was another typical photo reconnaisance satellite, deorbited 951218: To Recon sat Cosmos 2305 graph. Other EORSATs that decayed normally : To EORSAT Cosmos 2244 graph. EORSATs that decayed slowly at first : Note that, approximately midway through the decay, ndot2 (the time derivative of Mean Motion) suddenly multiplies by a factor of 4-5 ! To EORSAT Cosmos 2258 graph. To EORSAT Cosmos 2238 graph. EORSATs that decayed slowly all the time : Note that because the orbit correction system apparantly was operating during the entire decay phase, my normal approximation function does not work (the shape of the curve is different, not only the slope)! To EORSAT Cosmos 2264 graph. Back to my Home Page.