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April continues with recovery efforts concerning AO-40. The satellite is healthy and recent reports indicate that very good telemetry along with excellent downlink signals have been received recently.
The most exciting news is that successful transponder and matrix operation has been performed. The following is from AMSAT-DL:
On orbit 226, the U, L and U+L receiver passbands were connected to the (S-2) S-band downlink and were briefly checked out by command stations G3RUH and W4SM - using PSK, CW and SSB signals for the uplink. The tests worked extremely well and confirm that the matrix switch is working in these combinations. This prepares the way, with confidence, for transponder operation very soon, when the attitude approaches ALON-0/ALAT-0, via on-going magnetorquing.
Stay tuned for further announcements regarding general transponder operations!
Peter, DB2OS, for the AO-40 Command Team
AMSAT-NA President Robin Haighton, VE3FRH, recently completed a conversation with the ARRL concerning AO-40; the complete story is included here:
AMSAT-NA President Robin Haighton, VE3FRH, this week raised the possibility that AO-40 could inaugurate transponder operation this summer, if tests and orbital maneuvers between now and then go as planned. "We are learning how to fly this thing," Haighton said. "But I still think we're going to end up with a darned good satellite."
The most likely initial transponder configurations would be Mode U/S, or 435 MHz up and 2.4 GHz down -- and Mode L/S -- 1.2 GHz up and 2.4 GHz down. "It looks like a good bet," Haighton said of the probability that the two modes would prove useful from the damaged satellite. He predicted that Mode U/S operation from AO-40 would surpass what had been available a few years ago from the now-defunct AO-13. "We're getting something like 27 dB more signal."
Recent data from the spacecraft suggest that the mid-December incident that silenced AO-40 for two weeks and rendered some systems unusable also might have blown a hole in the spacecraft. Haighton said ground controllers have detected a distinct rise in temperature when the Sun faces parts of AO-40. "Speculation is there could be damage, and sunlight is getting right in," he said. That theory would go along with the loss of the satellite's omni-directional antennas, Haighton added. The speculated opening was not causing any major problems, he said, but it could explain why efforts to adjust AO-40's attitude via magnetorquing have been unpredictable.
As the AO-40 recovery effort continues, Haighton said, ground controllers plan to boost the satellite's orbit in the very near future. That process, using the onboard arcjet motor, could take up to several weeks. The AO-40 team hopes the maneuver will minimize or eliminate possible effects on the satellite's orbit caused by atmospheric expansion at the peak of the solar cycle.
AO-40 currently is approximately 200 miles above Earth at perigee and some 31,600 miles at apogee. Plans call for raising the orbit at perigee to around 320 miles. The maneuver would "hardly affect" the satellite's apogee, Haighton said. The arcjet would be operated without electrically igniting it -- using the pressure of the ammonia fuel alone. This would yield about half the normal thrust, Haighton said.
Once the orbit has been adjusted, ground controllers would orient the spacecraft's attitude and check out the various onboard transmitter and receiver systems to see what works and what does not. "We're still pretty confident that the 2-meter and 70-cm transmitters are not there," Haighton said, "but we're equally confident that the receivers for those bands still are."
The satellite has been transmitting telemetry on the 2.4 GHz (S-2) beacon, and signals reportedly have continued to improve - although the beacon has been out from time to time as needed to conserve power during eclipse periods. Ground controllers recently commanded the YACE camera to take several pictures, starting with orbit 216, and 11 images were downloaded. "The pictures show the characteristic rings and blisters that have been detected on the YACE photographs since the December 13 incident (damage to the lens from fuel residue?)," said a posting on the AMSAT-DL Web site. A prevailing theory about the image degradation was that the camera may have been damaged by direct sunlight into its lens, but James Miller, G3RUH, in an analysis subtitled "Did the Cameras Fry?" has disputed that notion.
Full deployment of the spacecraft's solar panels is still "down the road at least two to three months," Haighton said. Also uncertain was the satellite's ultimate inclination with respect to the equator. It was planned for AO-40 to have a 60-degree inclination, but given the satellite's compromised circumstances, "we'll be lucky if we can get 10 or 15 degrees," Haighton said. The current inclination is six degrees.
Paul, VP9MU, reported that additional pictures (using the YACE camera) were performed at the end of orbit 225. AO-40 then downloaded the photos via D-block telemetry through orbit 226. Paul reported that "we expect around 180 D-blocks in the complete set."
Moe, AE4JY, reported the following concerning his AO40Rcv Telemetry decoding program:
"I just found a nasty bug in the AO40Rcv program. It will crash if it is started in the minimized state. The bad part of this is that if the program is closed when minimized, it will always try to start up in a minimized state."
Moe reports a fix for this condition will be listed on the AE4JY web site in the near future.
[ANS thanks AMSAT-NA, AMSAT-DL and the ARRL for this information]
Mission STS-100 continues as this edition of ANS is broadcast. During the past week troubleshooting efforts designed to restore full capability to Alpha's three redundant command and control computers continued. Initial troubleshooting efforts have failed to resolve the problem, and flight controllers once again worked a procedure to re-string data management functions to the third computer, however, the computer problems continue and flight control teams are evaluating the situation.
Reloading the Raffaello logistics module with unneeded station equipment and supplies for return to Earth also took place. The Italian Space Agency-provided Raffaello logistics module is now loaded with 1,600 pounds of material and is tucked securely in Endeavour's payload bay. A practice run with the new station arm to rehearse moves the arm must make during the next shuttle assembly mission to the station (to attach a new airlock) were also conducted.
As this edition of ANS was prepared, Endeavour had backed away from the International Space Station as the two spacecraft soared 240 miles over the South Pacific Ocean, east of Australia.
As Pilot Jeff Ashby slowly backed Endeavour away, Commander Kent Rominger and Expedition-2 flight engineer Susan Helms exchanged final wishes for Endeavour's planned return to Earth, and a continued safe journey for the station crew. Once Endeavour was at a distance of 450 feet from the station, Ashby initiated a three-quarter circle flyaround of the station as Mission Specialist Yuri Lonchakov activated a large-format IMAX camera in Endeavour's payload bay to photograph the station.
On board the station, the Expedition-2 crew - Commander Yury Usachev and Flight Engineers Jim Voss and Helms - will enjoy some time off following a busy week on orbit. Early Monday morning, they will support the docking of a replacement Soyuz spacecraft that will serve as the station's lifeboat. The Soyuz and its crew of three, Commander Talgat Musabayev, Flight Engineer Yuri Baturin and American businessman Dennis Tito -- is scheduled to dock very early Monday morning.
The ARISS team informed ANS that the crew had left the ISS ham radio gear turned on recently. Several stations reported QSO's with ISS, including AMSAT Awards Manager Bruce Paige, KK5DO, and AMSAT-NA Vice President W2RS. Ray reported working Jeff Ashby, The shuttle pilot of the STS-100 mission. Ken, WA1QXR, also worked Ashby. Ken was mobile at the time using 20-watts into a 5/8-wavelength vertical on car roof.
Those that are still unclear on how to work the ISS amateur radio system are encouraged to carefully review the ARISS web page at http://ariss.gsfc.nasa.gov/
[ANS thanks NASA an the ARISS team for this information]
ANS news in brief this week includes the following:
Link to the weekly report on satellite ...
ISS . RS-12 . RS-13 . RS-15 . AO-10 . UO-11 . UO-14 . AO-16 . DO-17 . WO-18 . LO-19 . FO-20 . UO-22 . KO-23 . KO-25 . IO-26 . AO-27 . FO-29 . TO-31 . GO-32 . SO-33 . PO-34 . SO-35 . UO-36 . AO-40 . SO-41 . SO-42
Please send any amateur satellite news or reports to the ANS Editors at email@example.com, or to ANS Editor Dan James, NN0DJ, at firstname.lastname@example.org.
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This week's AMSAT News Service bulletins were edited by AMSAT News Service editor Dan James, NN0DJ.