Today, April 22, 2006, happens to be the 40th anniversary of the launch of a small satellite called Orbiting Vehicle 3-1, or OV3-1, from Vandenberg AFB. The reason it appeared on my "radar screen" yesterday is a cataloguing anomaly that became apparent on my "trek" through the orbited objects of 1966. The launch, which became 1966-034, resulted in four orbited objects in the current Space Track catalogue, namely, 2150 (1966-034A, the satellite OV3-1 itself), 2167 (1966-034B, the Scout B FW-4S fourth stage), and two minor pieces of debris, 2208 and 2209 (1966-034C and -034D). I was interested in determining what the two pieces of debris might be. Jonathan McDowell's website describes them as despin weights, but with a question mark. I figured their earliest-known orbital elements might support this notion. Although the accounts of this satellite (and its five later relatives, OV3-2 throughOV3-6) that I have seen do note that it was spin-stabilized, none specifically mentions despin weights. Photos of the spacecraft do seem to show cables wrapped around the satellite's equator that could plausibly be despin-weight cables, so it's a good bet, in the absence of a detailed confirmatory online account of the satellite's architecture, that the two objects are indeed despin weights. OV3-1 (and the other five OV3 spacecraft) was an octagonal prism about 74 cm across and 74 cm high, covered with solar cells and with an assortment of short booms and antennas extending from the top, bottom, and equator. It, along with its attached FW-4S rocket, was set spinning at launch inside the Scout B fairing, for stability and to distribute the solid-fueled fourth-stage thrust evenly after fourth-stage separation. After separation from the fourth stage and insertion into orbit, the satellite did somehow have to be despun, though not completely. Despin weights usually come in pairs, and when they are deployed, they carry angular momentum off in opposite directions from the parent satellite, so that one typically goes into a higher orbit and the other goes into a lower orbit than that of the parent. We can call them the "high despin weight" and the "low despin weight," respectively. I wanted to see whether the earliest-known orbital elements of 2208 and 2209 conform to this pattern. This would pretty much clinch their identification as despin weights. Although 2209 (1966-034D) has archival orbital elements extending continuously back to shortly after the launch date, much to my surprise 2208 does not. Its archival orbital elements begin with epoch 4/29/1986, more than 20 years after launch(!). This circumstance alerted me to some kind of cataloguing monkey business going on, and ultimately it resulted in this little note. I have copies handy of the June 30, 1985 and December 31, 1986 Goddard Satellite Situation Reports (my earlier ones are buried inaccessibly somewhere in my garage right now), so I looked up the 1966-034 launch therein. I was, once again, surprised to find 1966-034C listed as decayed December 5, 1976 (it is listed as in orbit in the current SatCat), and a fifth object, 9998 1966-034E, listed as part of the launch, still in orbit. What was this? And whatever had become of 9998 in the current SatCat? A quick look found 9998 currently listed as 1974-033F: the apogee kick motor of the geosynchronous meteorological satellite SMS-1, the kick motor itself being in an orbit somewhat below the geostationary orbit. That is, 9998 currently has nothing to do with the 1966-034 launch! So, what exactly was being tracked as 1966-034E back in the 1980s?? I punched up the archival elements for 9998, and lo and behold, I found that they extend, under the identification 1966-034E, all the way back to June 14, 1966, and this despite that fact that catalogue number 9998 was not assigned to anything until circa December 1976, more than ten years later: quite close, actually, to the date that 1966-034C is supposed to have decayed. Coincidence? There are quite a few TLEs archived under catalogue number 9998. Here are the highlights: The first TLE has the June 14, 1966 epoch. Then the TLEs run pretty much continuously through January 1, 1975, when there is a break of more than two years, and they pick up with the May 12, 1977 epoch. The last epoch that 9998 appears as 1966-034E is October 1, 1998, after which it suddenly becomes 1974-033F and acquires completely different orbital elements. The TLEs then extend continuously to date, identified as 1974-033F. My guess at what happened is this. 1966-034C was tracked through January 1, 1975 and then (being a small object in a fairly high orbit) was lost for about two years, during which time, despite showing no sign of orbit decay at its latest epoch, it was administratively decayed December 5, 1976. It was rediscovered around May 12, 1977, but since as 1966-34C it was already listed as decayed, it was called 1966-034E and given the new catalogue number 9998. Somewhere along the line, all those old -034C TLEs were redesignated 9998 1966-034E, so if you want the earliest known orbital elements of 2208 1966-034C, you'll now find them under 9998 1966-034E. The archival 2208 1966-034C TLEs pick up seamlessly from the earlier 9998 1966-034E TLEs. In 1986, someone at Space Track figured all this out and reinstated the old catalogue number 2208 and the old designation 1966-034C, and dropped the incorrect December 5, 1976 decay date, but unfortunately Space Track didn't stop compiling TLEs for that object under catalogue number 9998, too, for another ten years. If you sample TLEs for 2208 and 9998 for the same epochs between the years 1986 and 1998 (say October 1, 1998), you'll find they're virtually identical; Space Track was evidently tracking one object (1966-034C) under two different catalogue numbers and identifications (2208 1966-034C = 9998 1966-034E). Then, after October 1, 1998, Space Track finally dropped the redundant 9998 listing and reassigned that catalogue number to 1974-033F, which I guess happened about the time that object was actually discovered (I find no earlier TLEs for 1974-033F). Going by the 1966 TLEs for 1966-034C, as listed under 9998, I find that -034C would be the high OV3-1 despin weight and -034D (whose TLEs all seem to be OK) would be the low OV3-1 despin weight. There is no longer a catalogued object 1966-034E, and the online RAE table (which lists five objects for this launch, with -034E as decayed December 1, 1982 with a question mark) should be revised accordingly. The low despin weight, 1966-034D, re-entered December 4, 1989; the FW-4S (1966-034B) re-entered November 14, 2000. The four other, later, successful OV3 launches (one failed: OV3-5) all seem to have associated pairs of despin weights in orbit (along with, in some cases, other hardware), although I have not yet gotten around to analyzing them in detail. The OV satellites were built and launched under the auspices of the US Air Force Office of Aerospace Research (OAR), mainly as pickaback subsatellites with other payloads; the OV3's were the only ones launched standalone on their own rockets (Scout B's). ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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