Bart De Pontieu said: >A friend of mine is working on data obtained by the IRM-1 satellite, which >was part of the AMPTE-project. IRM-1 was built at our institute (MPE) and >she told me IRM-1 had burnt up in the atmosphere. But in the last Satellite >Situation Report I found this entry: >15200 84-088B IRM 1 (AMPTE) FRG 2653.1 27.0 13808 402 >The original orbit was one with an apogee of 120000 km and apogee of 560 >km. [snip] >Maybe it *did* decay without Spacecom knowing about it, since >they don't track it frequently ?? >I could check this if I had access to older SSR's, but they do not seem to >be available electronically before 1993/1994? Can anyone confirm this ? >More generally, I think it would be really interesting to have an archive >of old elements of satellites available electronically. Old elements are very >useful for research purposes, and I presume Spacecom has them stored >somewhere. Maybe someone who has influence with Spacecom could persuade >them to make old elements available ? >Maybe Spacecom or OIG are already working on this ? >Anyone know ? This is weird, even for Spacecom, which isn't known for rigor in its maintenance of orbital elements (I blush for my country ;) ). Here is the "last five" download for 1984 88B from NASA Goddard, done today, 19 Feb 1996: Element set number = 1 1 15200U 84088B 85165.07498243 -.00000353 +00000-0 +10000-3 0 05776 2 15200 027.0326 344.5409 8932020 038.8095 018.6999 00.54276908001640 Element set number = 2 1 15200U 84 88 B 85165.07494771 -.00000323 00000-0 99999-4 0 1709 2 15200 27.0326 344.5409 8932020 38.8095 18.6999 0.54276908 1640 Element set number = 3 1 15200U 84 88 B 95165.07498243 -.00000323 00000 0 99999-4 5778 <-- ! 2 15200 27.0326 344.5408 8932020 38.8095 18.6999 0.54276909 1640 Element set number = 4 1 15200U 84088B 85165.07493614 -.00000428 00000-0 10000-3 0 3640 2 15200 27.0326 344.5409 8932020 38.8095 18.6999 0.54276908 1640 Element set number = 5 1 15200U 84 88 B 85165.07495928 -.00000327 00000-0 00000+0 0 347 2 15200 27.0326 344.5409 8932020 38.8095 18.6999 0.54276908 1640 Objects in such highly elliptical orbits typically experience strong lunar/solar perturbations which cause the perigee to fluctuate significantly. I'd guess IRM is long dead, despite the "95165" epoch in the third element set. As for historical data sets, it would be nice if Spacecom or NASA would issue a CD ROM archive, but I know of no serious effort to do so. The total volume of data isn't particularly daunting: a ludicrous upper bound (LUB) can be estimated by assuming that 1e4 objects have been tracked once per day since 1958, generating one 140 byte element set per object per day: 1e4*1.4e2*3.65e2*3.8e1 ~= 19 gigabytes. Compress this with pkzip or similar to get ~7.5 Gbytes: a dozen current CD ROMs, one or two of the new generation (I don't remember what they're called). In reality, I'm sure the amount of data is less than a quarter, quite possibly less than a tenth of this LUB estimate. One possibility for justifying a request for blanket release of the element sets could be that time-series analyses of satellite orbits can be used to monitor the upper atmosphere. Global change studies might find this sort of information useful. (Now that I've said that, the name "Al Gore" comes to mind -- the US VP has pushed in the past to have other Cold War data released for scientific use, and might do so in this case.) Short of the Vice President, Prof. Tom Kelso (firstname.lastname@example.org) of the Air University at Maxwell AFB in Alabama is the person who seems best able to divine what is and isn't possible at Spacecom, so I'd suggest asking him about a Grand Archive project. Finally, It might be worthwhile to ask the Russian Space Forces about their orbital element archives -- they have a home page linked to IKI's.