SB SAT @ AMSAT $ANS-343.01 THE END OF AMSAT-OSCAR 13 HR AMSAT NEWS SERVICE BULLETIN 343.03 FROM AMSAT HQ SILVER SPRING, MD, DECEMBER 08, 1996 TO ALL RADIO AMATEURS BT BID: $ANS-343.01 On December 5th, 1996, apparently at approximately 0900 UTC, AMSAT OSCAR-13 re-entered the Earth's atmosphere and burned up. AMSAT OSCAR-13 was successfully launched on June 15th, 1988, into a highly elliptical orbit on board the first test flight of the new European ARIANE 4 rocket. Over the years, AMSAT OSCAR-13 has enabled direct radio contacts among the world-wide community of nearly 2 million radio amateurs. AMSAT OSCAR-13 had been constructed within four years by an international project group under the leadership of Dr. Karl Meinzer of AMSAT-DL. During its operational period, AMSAT OSCAR-13 was monitored and controlled by a group of ground stations in Germany, the United Kingdom, Australia, New Zealand and the U. S. Upon its re-entry, AMSAT OSCAR-13 has had a lifespan of over eight years. Originally the mission had been conceived to last only seven years. Overheating of the satellite due to air friction in the upper atmosphere resulted in the destruction of the solar panels on November 24th and the consequent interruption of all radio links. Amateurs were still making use of the satellite's Mode B transponder as late as about 2300 UTC November 23. Prior to this the on-board monitoring system had transmitted much data relating to the satellite's behavior in the upper atmosphere to ground stations for evaluation. When asked about the cause of AO-13's demise, Dr. Thomas Clark W3IWI commented that "the decay of the orbit was caused by the gravitational attraction of the Sun and the Moon. The elliptical orbit was stretched so that the satellite gradually approached the Earth which lies at one of the two focal points of the ellipse. This phenomenon motivated AMSAT to develop new analytical and computational methods to allow long term predictions for future satellites on similar, highly elliptical orbits". Her further emphasized that " the underlying cause of the AO-13 "crash" was NOT atmospheric drag. AO-13 was intentionally put into a high eccentricity "Molniya" orbit with an eccentricity ~0.7. Such orbits are unstable because of the gravitational effects of the sun and moon. Just like the tides in the ocean, the satellite is "nudged" gently by the sun and moon twice per orbit". Dr. Viktor W. Kudielka A.R.S. OE1VKW further noted that " Contrary to the true Molniya orbits with a liberating argument of perigee near 270 degrees (apogee always more or less in the north) due to an inclination around 63 degrees, AO-10 and AO-13 (at inclinations of 26 and 56 degrees respectively) show circulating arguments of perigee. The major problem for AO-13 was the 2:1 resonance of nodal to apsidal motion (near 56 degrees inclination). When calculating the orbit of AO-13 beyond the actual reentry, height of perigee is varying between -115 km and +5000 km with a period of about 40 years. James Miller G3RUH commented that Dr. Kudielka statement can be explained by saying that the drift of RAAN is proportional to the cosine of the inclination, and the drift in Argument of perigee is proportional to (5*Cos^2(IN) - 1)/2 and their ratio is thus 2*C/(5*C*C-1) where C=Cos (IN). For IN=56.1 degrees, this ratio comes out at just 2:1. So as the argument of perigee goes right round the clock once, the RAAN does it twice. The interactions from Sun and Moon cause Eccentricity to fluctuate. The magnitude of this fluctuation is strongly influenced by that 2:1 factor. If, as with AO-13, eccentricity fluctuates too much, the satellite crashes into the Earth." In fact G3RUH continued, "AO-13's inclination was about 57 degrees, so its "resonance" was nearer 2.25:1. RAAN went "round the clock" in just under 6 years, Arg. Perigee would have been about 13 years, and after 40 years all the cherries line up again; 7 RAANs to 3 ARG-Ps." Miller concluded that "These kind of interactions have been the focus of continuous study by Viktor OE1VKW for nearly a decade, and are central to making a wise selection of P3D's orbit. His analysis, simulation and above all interpretation have been continuously documented in the interim, and are a remarkable contribution to our understanding of this discipline." ANS notes that both Drs. Clark and Kudielka as well a James Miller G3RUH made very accurate predictions of the end of AO-13 long before the event actually took place. Dr. Clark's July 1990 prediction, done in collaboration with Dr. Erricos C. Pavlis, called for re-entry sometime on 5 December, 1996. In response to questions regarding the possibility of the same fate befalling the next AMSAT satellite, Phase 3-D, as G3RUH has indicated, it's orbit has been calculated using these new methods and has been determined that it will be more stable over the long term. In addition, Phase 3-D will carry a long lifetime low thrust arc-jet propulsion system intended to be used to correct any orbital perturbations which might occur. Phase 3-D is scheduled to be launched into space during the first half of 1997 as apparently the only satellite payload for the second test flight of the new ARIANE 5 launcher. ANS thanks Peter Guelzow DB2OS, James Miller G3RUH, Viktor W. Kudielka OE1VKW and Tom Clark W3IWI for the information used in preparing this bulletin. /EX SB SAT @ AMSAT $ANS-343.02 KO-23 RECEPTION PROBLEMS HR AMSAT NEWS SERVICE BULLETIN 343.02 FROM AMSAT HQ SILVER SPRING, MD, DECEMBER 08, 1996 TO ALL RADIO AMATEURS BT BID: $ANS-343.02 ANS has received a comment from the operating manager for KO-23, HL0ENJ regarding recent reports of difficulty in receiving data from KO-23. Our interpretation of the is response is that during continuous sunlight periods the spacecraft heats up, shifting the frequency of an oscillator. The transmitter is designed with a mechanical cavity resonate filter, which cannot be shifted or widened, HL0ENJ's recommendation is that users employ a receiver bandwidth which is in excess of what would normally be needed for receiving 9.6 kbps. It is further noted that 15 KHz is not wide enough to receive the signal well, and that 20 KHz is preferable. [ANS thanks HL0ENJ for the material used in this bulletin.] /EX SB SAT @ AMSAT $ANS-343.03 HOUSTON AMSAT NET HOLIDAY SCHEDULE HR AMSAT NEWS SERVICE BULLETIN 343.03 FROM AMSAT HQ SILVER SPRING, MD, DECEMBER 08, 1996 TO ALL RADIO AMATEURS BT BID: $ANS-343.03 The Houston AMSAT Net **WILL NOT** be linking with the W0KIE Network for their normal feed on December 24th and December 31st. There will be no update to the RealAudio files either. [ANS thanks Bruce Paige, KK5DO, AMSAT Area Coordinator for this news.] /EX SB SAT @ AMSAT $ANS-343.04 WEEKLY SATELLITE REPORT PT 1 HR AMSAT NEWS SERVICE BULLETIN 343.04 FROM AMSAT HQ SILVER SPRING, MD, DECEMBER 08, 1996 TO ALL RADIO AMATEURS BT BID: $ANS-343.04 FO-29 (Fuji OSCAR 29) No report available MIR: MIR on 145.200 (Downlink) MIR on 145.800 (Uplink) For packet operation 145.800 is used for both Tx and Rx operation (i.e. Simplex). [ANS thanks Joe Dreifuss, WA2GSY, for this information on MIR.] SAFEX, the 70cm repeater on MIR, is up and running. RS-12: Operating normally. With strong downlink signals reported both on 2 and 10 meters. RS-10: Operating normally. Very busy with lots of QSOs heard over north America and Europe. RS-15 Operating normally. (Hint: If SSB doesn't work for you, try CW. CW is very easy to hear on the downlink!) KO-23: See accompanying bulletin. KO-25: KO-25 Satellite is operating but is still closed for uploads. No information is available about the return to full service [ANS thanks Jim Weisenberger, AA7KC, for his reports on KO-25. AO-27: As of NOV 2, the AO-27 schedule is as follows: TEPR 4 = 16 = 8 Minutes in Length TEPR 5 = 52 = 18 Minutes in Length TX-3 is on Mid Power during TEPR 5. This will have the TX turn on 8 Minutes after the satellite enters the sun for a duration of 18 Minutes. This is a "back to US Latitudes"operation. N4USI, AO-27's current Command Station sends his thanks all for their messages about the satellite turning on later than expected. He reports he's deliberately letting the "turn on" time drift later (for about 4-5 Minutes) so stations in the southern latitudes can also have a chance to work AO-27. Every few months he will be letting the turn on time drift like this to give more stations a chance to make contacts thru the satellite. [ANS thanks Michael, N4USI , AO-27 Control-op, for this update.] AO-10: Operating normally. ANS thanks S. Badessi for this report.] /EX SB SAT @ AMSAT $ANS-343.05 WEEKLY SATELLITE REPORT PT 2 HR AMSAT NEWS SERVICE BULLETIN 343.05 FROM AMSAT HQ SILVER SPRING, MD, DECEMBER 08, 1996 TO ALL RADIO AMATEURS BT BID: $ANS-343.05 AMSAT-OSCAR-16 (PACSAT) Continues in good working order. FO-20 Strong downlink signal and very busy with activity. OSCAR-11 Good, steady signals have been received from OSCAR-11 on 145.826 MHz. Once again there has been a small rise in the internal temperatures, which are now at the maximum values recorded in January. Telemetry values are nominal, although the battery voltage of around 13.8 is slightly below the levels recorded a few months ago. The 14 volt main bus current is steady at 635 milli-amps. The WOD survey is unchanged. The WOD, channels 0, 10, 20, 30, solar array currents, dated 17-September, has been transmitted during the month. The operating schedule is unchanged. ASCII status (210 seconds) ASCII bulletin (60 seconds) BINARY SEU (30 seconds) ASCII TLM (90 seconds) ASCII WOD (120 seconds) ASCII bulletin (60 seconds) BINARY ENG (30 seconds) There are also additional status blocks after each bulletin is transmitted, and between ASCII TLM and WOD. The mode-S beacon is ON, but telemetry indicates that it has partially failed. There have been two reports of it being heard weakly, since the failure. Any reports of reception on 2401 MHz. would be most welcome. Please e-mail g3cwv@amsat.org. The 435.035 MHz. beacon is normally OFF. However it can sometimes be heard when the satellite is being commanded by ground control, i.e. within range of Guildford, UK. Likely times are between 1500 and 1800 UTC, Fridays or at weekends. When the 435 beacon is transmitting, the 145 beacon is normally OFF. The data transmitted is mainly BINARY. [ANS thanks Clive Wallis, G3CWV, for this information.] IO-26 ( ITAMSAT): Operating normally. Some report indicate that the downlink signals from the bird are stronger. [ANS thanks Richard W L Limebear, G3RWL, for this report.] DO-17(DOVE) Jim White reports that DOVE had timed out on December second. DOVE's software was then uploaded again to correct the time out problem. Signals from Dove are once again being received. [ANS thanks Jim White, WD0E, and Sergio Adrian Gorgone, LW7DXF, for this information.] LUSAT-OSCAR-19 continues to perform well. [ANS thanks SpaceNews for this report.] . WEBERSAT (WO-18) The satellite remains in good condition, and the kernal will be reloaded and started very soon. When the software fault has been located and corrected, the remaining task(s) will be uploaded and started. [ANS thanks Tommy Davis, IK3WVJ, for this report.] [Please send your Satellite reports to bjarts@uslink.net or to wt0n@amsat.org] /EX