Jonathan's Space Report No. 523 2004 Apr 7, Somerville, MA ------------------------------------------------------------------------------- Kosmos-2406 =========== Russia launched Kosmos-2406 on Mar 27 into geostationary orbit. The launch vehicle was a Proton-K with a Blok DM-2 upper stage, in contrast to the Mar 15 launch of the more modern Proton-M and Briz-M combination. Kosmos-2406 is a Globus military communications satellite. The first orbital data show the satellite in an unusual subsynchronous 1329.92 minute, 32307 x 35056 km x 0.0 deg drift orbit, with a perigee over 3000 km lower than normal Russian GEO insertions. (As of April 7, no further orbital data was available). The previous Globus satellite, launched in Oct 2001, also was tracked in such an orbit the day after launch, and then found again in a normal GEO orbit two weeks later. The reason for this new launch profile is not obvious. WDC-A and Space Command are reporting the satellite as Kosmos-2407, presumably because the original Russian launch schedule stated the now-delayed Zenit-2 launch would be Kosmos-2406. However, after launch Novosti called the new satellite Kosmos-2406, implying that the Kosmos numbers will continue to be assigned in launch order, and so provisional numbers released before launch may change. This makes sense since the Kosmos numbers are used purely for public consumption, with internal classified military names used in all technical documentation, so changing the Kosmos number at a late date doesn't break anything. TASS reported the launch as a `four tonne satellite' which is simply an error, as the Proton does not have the capacity to put such a heavy satellite in the orbit achieved. The Kommersant story says 2 tonnes, which is correct. The Blok-DM final stage from Kosmos-2406 has not yet been cataloged; neither has the Briz-M stage from the Eutelsat launch two weeks ago. There were two kinds of Kosmos satellite launched in the recent past to GEO - the Lavochkin US-KMO Prognoz early warning series, and the NPO-PM Geizer military communications satellites. The last Geizer launch was Kosmos-2371 in Feb 2000; the last US-KMO launch was Kosmos-2397 in Apr 2003. The US-KMO series has been plagued with failures, with only the 2001-launched Kosmos-2379 still operating, and Kosmos-2371 is the last operating Geizer, so originally I suspected Kosmos-2406 could be a replacement in either series. David Todd suggested to me that instead it might be a Globus military communications satellite and this has now been confirmed by a story in the Kommersant newspaper. Earlier Globus launches were given the Raduga-1 cover name, but it looks like the Russian Defense Ministry may be consolidating all its launches under the Kosmos cover name now (as for last month's Kosmos-2405 launch). Navstar 59 ========== A new Navstar GPS (Global Positioning System) satellite was launched on Mar 20. SVN 59, the 11th Block IIR launch, rode to space on a Boeing Delta 2 from Cape Canaveral's Space Launch Complex 17B. The Delta second stage reached a 174 x 200 km orbit at 1803 UTC; after its second burn the third stage separated at 1857 UTC and fired to enter an elliptical transfer orbit. The GPS satellite separated from the third stage at 1901 UTC, followed two seconds later by a `yo weight', a small weight attached to a 1-meter cable which unwinds from the spinning PAM-D stage and whose departing angular momentum is used to tumble the stage and make sure that residual thrust doesn't cause it to hit the payload. I've been obssessing about these yo weights recently. Humour me, Gentle Reader - it's harmless and keeps me off the street where I might be fomenting revolution instead. Here's the problem: solid propellant upper stages are usually fired while spinning rapidly to keep them stabilized. After separation of the stage, you usually don't want your payload spinning fast. One way of fixing this, invented independently by JPL and APL in the early years of the space age, is the despin weight or `yo-yo device', in which a pair of long wires with masses on the ends are wrapped around the vehicle. When the masses are unclamped from the satellite, the spin unwinds the wires, and angular momentum is transferred from the satellite to the masses. When the wires have fully unwound they are released and each wire-plus-mass pair becomes a piece of space debris. For early satellites the despin weights were wrapped around the satellite itself, but for modern Delta launches the weights are attached to the third stage and are released after third stage burnout but about 5 seconds before third stage/satellite separation. The despin weight idea is a one-use-only solution and some satellites have more sophisticated forms of spin control, using magnets or gas jets - for instance, the GPS satellite has its own solid motor for orbit circularization, and so it needs to be still spinning for that burn. In those cases a single weight is used by Delta third stages, and is released 2 seconds after third stage separation instead of 5 seconds before. The asymmetric transfer of angular momentum to the weight causes the third stage to tumble, so that if rocket exhaust is still escaping from the embers in the thrust chamber it won't go in the direction of the payload but will average out to zero net thrust. In the early days, there were several cases of a rocket stage bumping into its payload again after separation and causing damage, because of this residual thrust problem. The despin weight analogy with a yo-yo is a bit strained, and to the extent that it holds a single weight+wire is really the equivalent of a yo-yo, but nevertheless not only has the name stuck but the single-weight tumbler case has become known as a `yo' (half a yo-yo)! Every three-stage Delta 2 variant uses either a yo or a yo-yo, and so leaves one or two pieces of debris in orbit each with a mass of 1 kg and a cable length of 1.0m. In 1994 Space Command started cataloging some of these debris pieces, and it was a while before I figured out what they were. Not all the pieces have been cataloged; I present here a list of recent three-stage Delta 2 launches and their despin type. Date Delta Model Payload Despin type Catalog 1998 Dec 11 7425-9.5 Mars Climate Orbiter Yo-Yo No 1999 Jan 3 7425-9.5 Mars Polar Lander Yo-Yo No 1999 Feb 7 7426-9.5 Stardust Yo No 1999 Oct 7 7925-9.5 GPS IIR-3 Yo 26789 2000 Mar 25 7326-9.5 IMAGE Yo-Yo No 2000 May 11 7925-9.5 GPS IIR-4 Yo 27764 2000 Jul 16 7925-9.5 GPS IIR-5 Yo 27765 2000 Nov 10 7925-9.5 GPS IIR-6 Yo No 2001 Jan 30 7925-9.5 GPS IIR-7 Yo 27766 2001 Apr 7 7925-9.5 2001 Mars Odyssey Yo-Yo No 2001 May 18 7925-9.5 GeoLITE Yo-Yo No 2001 Jun 30 7425-10 MAP Yo-Yo No 2001 Aug 8 7326-9.5 Genesis Yo-Yo No 2002 Jul 3 7425-9.5 CONTOUR Yo No 2003 Jan 29 7925-9.5 GPS IIR-8 Yo 27773 2003 Mar 31 7925-9.5 GPS IIR-9 Yo No 2003 Jun 10 7925-9.5 MER-A Yo-Yo No 2003 Jul 8 7925H MER-B Yo-Yo No 2003 Dec 21 7925-9.5 GPS IIR-10 Yo 28189 2004 Mar 20 7925-9.5 GPS IIR-11 Yo 28193 Table of Recent Launches ----------------------- Date UT Name Launch Vehicle Site Mission INTL. DES. Feb 5 2346 AMC-10 Atlas IIAS Canaveral SLC36A Comms 03A Feb 14 1850 DSP 22 Titan 4B/IUS Canaveral SLC40 Early Warn 04A Feb 18 0705 Kosmos-2405 Molniya-M Plesetsk Comms 05A Mar 2 0717 Rosetta Ariane 5G+ Kourou ELA3 Comet probe 06A Mar 13 0540 MBSAT Atlas IIIA Canaveral SLC36B Comms 07A Mar 15 2306 Eutelsat W3A Proton-M/Briz-M Baykonur PL81 Comms 08A Mar 20 1753 Navstar SVN 59 Delta 7925 Canaveral SLC17B Navigation 09A Mar 27 0330 Kosmos-2406 Proton-K/DM-2? Baykonur PL81 Comms 10A .-------------------------------------------------------------------------. | Jonathan McDowell | phone : (617) 495-7176 | | Somerville MA 02143 | inter : jcm@host.planet4589.org | | USA | jcm@cfa.harvard.edu | | | | JSR: http://www.planet4589.org/jsr.html | | Back issues: http://www.planet4589.org/space/jsr/back | | Subscribe/unsub: mail majordomo@host.planet4589.org, (un)subscribe jsr | '-------------------------------------------------------------------------'