SB ALL @ AMSAT $ANS-184.01 Final AO-13 Motor Burn 06 July HR AMSAT NEWS SERVICE BULLETIN 184.01 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT AMSAT engineers estimate conditions will be right for the second and final kick motor burn by early this week. Wednesday, July 6, has now been pegged as the actual firing day. The second motor burn should put AMSAT OSCAR 13 in its final orbit now figured to have a slightly higher perigee than originally planned. The balance of the propellants will be expended in a "burn to depletion" strategy. About 85% of the propellants remain; enough for about 5 minutes of thrust. After its letter-perfect launch June 15, AMSAT Controllers first successfully fired AO-13's kick motor on June 22. The result was an intermediate orbit with perigee at 1081 km and inclination raised to 14.3 degrees. The final burn this week will raise perigee to about 2200 km and change the orbital plane from its current 14.3 degree inclination to as high as 57 degrees. Beginning immediately after the first burn, re-orientation and spin up proceeded. By Saturday, July 2, AO-13 had attained the desired second burn attitude (-59 degrees longitude; -70 degrees latitude in the Bahn coordinate system). It is estimated that by Monday, July 4, the spin rate will actually attain the desired 60 rpm. If the final burn comes on Wednesday, July 6, it will occur at apogee of orbit #47 at about 21:08 UTC. Although the satellite will not be in view of North America at the time, it will be easily viewed from Europe, Africa, the Middle East and most of South America. According to DB2OS, before and during the motor burn, the telemetry will be switched to the Engineering Beacon (145.985 MHz). It will then revert to the General Beacon on 145.812 MHz. After the burn, earth and sun sensor measurements will be made prior to beginning the re-orientation to the operational attitude. Getting the spin rate up to 60 rpm has taken considerable time due to the attitude of AO-13 with respect to the geo-magnetic field. Spinning up to the relatively high rate of 60 rpm is done for at least two reasons. First, the gyroscopic effect of the spin will stabilize the spacecraft during motor firing. Second, the fuel in the tanks will be forced towards the exit ports by the centrifugal force imposed on it by the spinning. This will insure most, if not all, of the fuel is expelled into combustion chamber. Once in its final orbit, it will be easier to despin and re-orient due to the orientation of the orbital plane with respect to the geo-magnetic field. A short-term study of electron and proton density at 1500 and 3000 km altitudes has been performed by the AMSAT DL team. It has been found neither prospective perigee altitude offers and distinct advantage over the other. The study was undertaken to ascertain whether changing the perigee target for AO-13 would affect its radiation environment and thus its lifetime. With neither perigee altitude showing a distinct advantage, it has been decided to raise the target perigee altitude from its former 1500 km to a new target of 2200 km. According to DJ4ZC, this will have two results: 1. It will add some insurance altitude should the second burn be other than fully successful. 2. It will improve coverage over the Southern Hemisphere. /EX SB ALL @ AMSAT $ANS-184.02 AO-13 Health Reported Good HR AMSAT NEWS SERVICE BULLETIN 184.02 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT All the telemetry indications from AMSAT OSCAR 13 show this to be a healthy satellite. Power generation is excellent and temperatures are all within expected ranges. The main battery temperature is hovering between 12 and 13 degrees Celsius and the 2 meter power amplifier is running at a comfortable 16 degrees C. The coldest reading monitored is in the Mode S transponder which is not currently activated. It's indicating a nominal 6 degrees Celsius. In general, all temperatures lie in a range of 6 to 19 degrees Celsius. AO-13 telemetry is transmitted in three forms: PSK (phase shift keyed); RTTY; CW. The RTTY uses FSK (frequency shift keyed) tones spaced 170 Hz at a signaling rate of 50 baud. RTTY telemetry is sent at 15 and 45 minutes past the hour. CW telemetry is sent at 10 wpm at 0 and 30 minutes past the hour. PSK telemetry is sent at other times at 400 baud. The Mode B General Beacon is at 145.812 MHz. Telemetry reception in many areas has been hampered by FM users many of whom are unaware 145.800 to 146.000 MHz is, by general agreement, a sanctuary for weak signal, satellite operations. Sixty four channels of telemetry are sent in PSK. The first 60 of these are sent in RTTY as well. The revised telemetry equations are presented in ASR #178 which is now in the mail. Telemetry indicated effects from the huge solar flare last Saturday, June 25. By Sunday, those monitoring AO-13 telemetry had already detected "hits" in the satellite's computer. Although no damage was expected and none occurred, the intense burst of radiation from the sun registered on AO-13 when its self-correcting devices were obliged to correct for radiation-induced errors in the IHU. These were seen as memory "soft errors" meaning a temporary upset caused by radiation had occurred. The AO-13 IHU and memory are extremely radiation resistant, a least a thousand times more than AO-10, and so the radiation hits are of academic interest but pose not real threat to its health. Watching the hits can, however, give an idea when solar radiation and particles arrive in the vicinity of earth. /EX SB ALL @ AMSAT $ANS-184.03 AO-13 Comm Ops In 2 - 3 Weeks? HR AMSAT NEWS SERVICE BULLETIN 184.03 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT With the second and final kick motor firing now slated for this coming week, potential users are awaiting word on when the new bird will be available for use. With things going extremely well in all aspects, the answer could be more sooner than later. According to reliable sources, once the second and final kick motor burn is accomplished, it will take about two weeks to re-orient the satellite and spin it down to about 30 rpm for general operations. Thus, if the motor burn occurs later this week, AO-13 could be released for use beginning in late July. A detailed operating plan for AO-13 will evolve after initial operations commence and will be based on operating experience including use levels. Initially, Mode B will be used almost exclusively with Mode JL used in modest proportions. Then, depending on use patterns, Mode JL use, especially around apogee will be gradually increased. After a certain period, Mode JL operation will likely predominate the operating schedule in order to take maximum advantage of its broad bandpass. Moreover, Mode JL will straddle apogee to take advantage of the high gain, narrow beam 24 cm helix on the satellite. The high gain antennas will be pointing directly at the geo-center when at apogee once the spacecraft is properly oriented. The narrow, 50 kHz, 2 meter J uplink in the 290 kHz Mode JL transponder, is intended primarily for and recommended for Third World uplinks. /EX SB ALL @ AMSAT $ANS-184.04 Refined AO-13 Tracking Data HR AMSAT NEWS SERVICE BULLETIN 184.04 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT The effort to refine the Keplerian elements for AO-13 continues with new AMSAT-derived ranging data being combined with radar tracking data. The result is an extremely good fit. Here is the latest set available which will be more than adequate for tracking until the final kick motor burn this week. Satellite: oscar-13 Catalog number: 19216 Epoch time: 88180.50000000 Tue Jun 28 12:00:00.0 1988 UTC Element set: mh6-28 Inclination: 14.3010 deg RA of node: 241.4520 deg Eccentricity: 0.7012999 Arg of perigee: 186.5090 deg Mean anomaly: 21.9710 deg Mean motion: 2.20041400 rev/day Decay rate: 0 rev/day/day Epoch rev: 29 Semi major axis: 24973.177 km Anom period: 654.422304 min Apogee: 36108.962 km Perigee: 1081.402 km New elements will be issued as soon as the new, post burn #2, orbit can be ascertained. A predicted post-KM#2 set may be issued early this coming week. /EX SB ALL @ AMSAT $ANS-184.05 Soviets Set For Phobos Mission HR AMSAT NEWS SERVICE BULLETIN 184.05 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT Preparations are under way this week at the USSR's Baikonur Cosmodrome for the first of two missions to Phobos, one of the two Martian moons. Phobos-1 and 2, set for launch on July 7 and 12 respectively, will travel for 200 days towards Mars where they will enter equatorial orbits around the "red planet" prior to achieving a synchronous orbit with Phobos. After some two months of analysis and observations, the Phobos vehicles will start closing with the Martian moon to a distance of 35 kilometers and finally to a height of 50 meters where they will "hover" above the lunar surface. For a period of 15 minutes, a series of studies including television transmissions, radioscopy of Phobos' internal structure, and laser and ion-ray irradiation of the lunar surface will be conducted. Nearly 150 laser pulses will evaporate particles of the soil, which are expected to rise to a height of over 50 meters. The traps mounted on the orbiters, it is hoped, will capture and analyze these particles with data being subsequently transmitted back to earth. Finally, the orbiters will drop two landing modules, one static and one a mobile "leaping" device. The leaping device will survey the surface as well as send back television panoramas of Phobos' landscape. The tiny, 27 km moon of Mars has been described as looking like a "bitten apple." In other Soviet space news, it is believed preparations are under way as well for an August launch of the Soviet Space Shuttle. Soviet space officials have made no mention of the shuttle in recent weeks but the August date was revealed during a media tour of the Cosmonaut training center at Star City in May. This will be the first orbital test of the shuttle and only the second test of the new, heavy lift launcher, Energia. /EX SB ALL @ AMSAT $ANS-184.06 Short Bursts HR AMSAT NEWS SERVICE BULLETIN 184.06 FROM WA2LQQ WARWICK, NY July 2, 1988 TO ALL RADIO AMATEURS BT Nominations for AMSAT-NA Director closed June 30. Those nominated included: Tom Clark, W3IWI; John Henry, VE2VQ; Phil Karn, KA9Q; Doug Loughmiller, KO5I; Andy MacAllister, WA5ZIB; Vern Riportella, WA2LQQ. Election materials will be sent out next month to all current members. There are four seats up for election this year. Handsome posters of AMSAT OSCAR 13 in orbit are now available from AMSAT HQ. Call or write to obtain yours. Here is the current AO-10 operating schedule: Through July 31: Mode B MA 25 to MA 235 August 1 - August 15: Mode B MA 30 to MA 240 The satellite will be unavailable for use beginning August 16 because of predicted insufficient solar illumination and reduced battery charge. If "FMing" of signals occur sooner that August 15, DO NOT USE AO-10 please. As always, please use minimum power required for communications. Listen to your nets for later updates, or to AMSAT OSCAR 13 beacons beginning in late July for any changes to this schedule. Here is the FO-12 operating schedule. Mode From (UTC) ---------------- JA Jul 02 0103 D 04 0116 JD* 07 1530 JD 07 1935 DI 08 0143 JD 09 0049 DI 09 2355 JA 13 1409 D 14 1315 JA 16 1328 D 17 1235 JD 20 1356 DI 21 1301 JD 23 1141 DI 24 1020 JD 26 1033 DI 27 1141 JD 30 1100 DI Jul 31 1006 JD = Digital mode JA = Analog mode D = All systems off DI = Systems off except CPU and memory *From 1530 to 1732 UTC, July 7, acquisition of telemetry will be every 2 seconds. The mailbox will be disabled during this interval. The transponders will be off at other times. The actual operating schedule may change due to unexpected situations such as variations in available power. /EX