SB NEWS @ AMSAT $SPC0628 * SpaceNews 28-Jun-99 * BID: $SPC0628 ========= SpaceNews ========= MONDAY JUNE 28, 1999 * AMSAT P3-D ROLLOUT * ====================== A team of experts and builders of the various transponders of the AMSAT P3-D satellite recently arrived at Orlando, Florida from Europe. The team included Matjaz Vidmar S53MV, Mirek Kasal OK2AQK, Michael Fletcher OH2AUE, Wilfried Gladisch, Peter Gulzow DB2OS, Werner Haas DJ5KQ and Karl Meinzer DJ4ZC. After testing and calibration of the spacecraft antennas, which were mostly build by Stan Wood WA4NFY and Freddy de Guchteneire ON6UG, the antennas were mounted to the spacecraft for the "rollout" when P3-D was transported outside for an "on air" test in full flight configuration. The spacecraft is protected from the Florida environment by a big sealed tent. After several exciting days of testing, the RF communications manager Werner Haas, DJ5KQ was happy to report to the Project Leader Dr. Karl Meinzer DJ4ZC of the successful completion of the rollout, and that all RF subsystems in the P3-D spacecraft worked nominally. Another big event was the successful testing of the 400N thruster from MBB and the 100mN ATOS Arcjet developed by the University of Stuttgart (Germany) with pressurizing of the whole propulsion system and fuel tanks. The test firing using Nitrogen gas was performed by Dick Daniels W4PUJ, Rick Leon KA1RHL, Karl Meinzer DJ4ZC and Peter Gulzow DB2OS. The next milestones are the Spin Balance test and the Vibration test, which will take place before the spacecraft is transported to the launch site. The vibration test could not be done earlier since designers had to wait for the final specification of the static and dynamic loads by the launcher agency. The P3D Team Lou McFadin W5DID P3D Integration Manager * AO-27 TEPR STATES * ===================== The AMRAD-OSCAR-27 satellite uses a method called Timed Eclipse Power Regulation (TEPR) to regulate its battery charge. In simple terms, TEPR times how long the satellite has been in the eclipse or in the sun, and decides what subsystems to turn on or off. The current software onboard AO-27 breaks an orbit into 6 different states as follows: TEPR State 1: Starts when the satellite enters the Eclipse TEPR State 2: Starts a programmed time after TEPR State 1 (still during the Eclipse) TEPR State 3: Starts a programmed time after TEPR State 1 that's after State 2 (still during the Eclipse) TEPR State 4: Starts when the satellite enters the Sun TEPR State 5: Starts a programmed time after TEPR 4 (Still in the Sun) TEPR State 6: Starts a programmed time after TEPR 4 that's after State 4 (still in the Sun) Current subsystems by state are as follows: TEPR 1, 2, 3 : All unneeded subsystems turned off (This is why there is no night time use of the satellite) TEPR 4 : AO-27's transmitter is turned to exciter power only. All other transmitters are off. TEPR 5 : AO-27's transmitter is turned to 0.5 watts (low power) TEPR 6 : All unneeded Subsystems are turned off Using this model, during a descending day-time pass, AO-27 will enter TEPR 4 after coming out of eclipse and will begin to recharge its batteries. Controllers program the TEPR 5 time so the satellite will stay in TEPR 4 until the footprint reaches latitudes equal to the Northern United States. At that time, it changes to TEPR State 5 and the transmitter turns on. The duration of TEPR State 5 is set for the longest controllers can leave the transmitter on to keep the satellite's batteries in a state that will prolong their life. At the current time (June 1999), this is 18 minutes. If controllers were to leave it on longer, the lifetime of the satellite could be shortened. The TEPR 6 period needs to be long enough to recharge the batteries before the satellite enters the eclipse again (TEPR 1). The time that is needed to stay in TEPR 6 is what places a limit on the southern latitudes that satellite can work in. Controllers command OSCAR-27 to charge its batteries for "x" number of minutes AFTER it enters the Sun. This is TEPR state 4 expressed in 30 second increments (e.g. TEPR 42 means that the charging time is 21 minutes). Controllers then set TEPR state 5 to the length of time, expressed in 30 second increments, that the transmitter would be on from the start of TEPR 4, but not on until the completion of TEPR 4 (e.g. TEPR 78 means that the transmitter will shut off 39 minutes after the start of TEPR 4, but the transmitter will be on for 18 minutes (78-42 = 36, or 18 minutes)). Chuck Wyrick, KM4NZ, acting AO-27 control operator, reset the TEPR states on AO-27 at approximately 14:20 UTC, 20-Jun-99 as follows: TEPR 4: 42 TEPR 5: 78 to give the best overall coverage during this year's Field Day activities. [Info via Chuck, KM4NZ, and Michael, N4USI] * STS-93 SAREX NEWS * ===================== The countdown to the launch of Space Shuttle Columbia on mission STS-93 is proceeding well. STS-93 will be a SAREX (Shuttle Amateur Radio Experiment) mission. STS-93 crew members include: Eileen Collins, KD5EDS Jeffrey Ashby Steven Hawley, Mission Specialist Catherine Coleman, Mission Specialist, KC5ZTH Michael Tognini, KD5EJZ WA3NAN, Amateur Radio Club station at the Goddard Spaceflight Center in Greenbelt, Maryland, is expected to be on the air providing re-transmissions of air-to-ground communications on the following HF frequencies: 3.860 MHz LSB 7.185 MHz LSB 14.295 MHz USB 21.395 MHz USB 28.650 MHz USB Launch of STS-93 is expected to occur no earlier than 20-July-99 at 12:36 AM EDT (21-Jul-99 0426 UTC). Columbia will be carrying the Chandra X-Ray observatory into a 153 nautical mile / 28.45 degree inclination orbit on this mission. * MIR TNC GLITCH * ================== Dr. Dave Larsen, President of MIREX, reports that when in packet radio mode, the 2-meter transmitter on-board the Mir space station is transmitting an unmodulated carrier rather than 1200 baud AFSK data. It is hoped that the problem may be resolved by simply re-seating the audio connector connecting the TNC to the 2-meter transceiver. In the meantime, some of the cosmonauts on Mir have been making 2-way voice contacts with groundstations on 145.985 MHz FM. * FEEDBACK/INPUT WELCOMED * =========================== Comments and input for SpaceNews should be directed to the editor (John, KD2BD) via any of the paths listed below: WWW : http://www.njin.net/~magliaco/ PACKET : KD2BD @ N2SMV.NJ.USA.NA <-------------- New address! 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