AMSAT-NAAMSAT News Service

February  25, 2001

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Phase 3D/AO-40 Update

The month of February comes to an end with good news about AMSAT OSCAR 40.

The AMSAT-DL web site is currently featuring the following statement from Peter, DB2OS:

Dear All,

Lots of good news about AO-40!

The SEU (sensor electronic unit) is triggering the sun again after the end of eclipse on orbit 147. Telemetry channel #100 (analogue spin rate) is now showing a value of 49. This is the same value it was showing on orbit 89 when triggering was lost. Within a few orbits we should see that the second Sun sensor (SS2) also starts triggering, this should allow us to obtain attitude information and then re-start the magnetorquing efforts to spin-down the spacecraft.

One week ago the 3-axis sun sensors were turned on and they seem to be working nominally. It was planned to use the information from the 3-axis omni-directional sun sensors to obtain the necessary reference information for a new algorithm to spin-down the spacecraft without using the SEU information. The new software code, which will be patched into the operational programming, is almost ready to be uploaded, but due to the premature return of SEU data, this may no longer be necessary.

Analysis of the IHU temperature has revealed that the maximum Sun angle (with the lowest temperatures) was much earlier than anticipated. The temperature of the IHU reached its minimum exactly February 1, 2001 with a temperature of about -8.4C. This is almost one month earlier than originally thought. There is no explanation at the moment as to why this was premature.

The spin rate of around 17.5 RPM did not changed in the last few weeks, whatever it caused to increase has apparently stopped. As soon as the SEU delivers good data, the magnetorquers will be used under control of the IHU to reduce the spin and make any possible attitude changes easier. This should also improve telemetry reception on the S-band downlink.

The next milestone is to bring the spacecraft into a good orientation to fire the arcjet using no electrical power only gaseous ammonia only. This test firing will be used to check the arcjet control electronics and valves. Even without the arcjet burning, the thrust from the test firing will be enough to raise the perigee.

Several independent analysis (including the French space agency CNES) have confirmed that the current orbit will be stable for many years, more than the anticipated lifetime of the spacecraft.

The test firing should give us additional safety margin and a better feeling. However, it is later planned to optimize the current orbit with a full running arcjet. This is planned after testing of the 3-axis momentum wheels, which will be used to re-orient the spacecraft during these maneuvers.

While the spacecraft was in hibernation, the command stations were in preparations for the next activities, watching the spacecraft telemetry and reporting healthy results.

AMSAT-DL expresses our appreciation thanks to Paul, VP9MU, for his outstanding service in gathering and archiving the AO-40 telemetry from different parts of the world. This is vital (additional) information for the command stations in their continuing effort to turn P3D back into normal operation. We suggest everyone who is able to send captured telemetry to the AO-40 telemetry archive at ao40-archive@amsat.org

In summary, the spacecraft seems to be in very good shape, with no additional damage or other problems detected. The power budget is very good and even during the poor Sun illumination it was not necessary to reduce power consumption by turning off the S-band transmitter for any part of AO-40's orbit.

This is indeed a good sign for the next activities.

Stay tuned...

73,
Peter, DB2OS

AO-40's orbital parameters (number 40) are as follows:

Satellite: 		AO-40
Catalog number: 	26609
Epoch time: 		01052.45100567
Inclination: 		5.6046 deg
RA of node: 		220.4851 deg
Eccentricity: 		0.8134917
Arg of perigee: 		224.8386 deg
Mean anomaly: 		29.8566 deg
Mean motion: 		1.26950859 rev/day
Decay rate: 		3.0e-08 rev/day^2
Epoch rev: 		143
Checksum: 		280

Stay tuned to AMSAT News Service, the official source of AO-40 news and information.

[ANS thanks AMSAT-DL and AMSAT-NA for this information]

Canadian ISS Contact Successful

The ARISS group and the ARRL have both reported that students at the Merivale Public School in Ottawa, Ontario, recently became the first Canadian students to speak with Space Station Alpha. The Contact was with ISS Commander William Shepherd, KD5GSL, who used the NA1SS callsign.

Reports that the Merivale ARISS contact probably will be the last school contact for the current crew of Shepherd, Yuri Gidzenko and Sergei Krikalev, U5MIR, may not be correct. AMSAT-NA's Will Marchant, KC6ROL, the ARISS spokesman, told ANS the team may try to do one more school contact. Following this, it will be sometime in late March before ARISS school contacts can resume, which will be after the Expedition-2 crew arrives.

Amateur radio coordinator Steve McFarlane, VE3TBD, worked in concert with the school in anticipation of the ARISS QSO. When VE3TBD raised NA1SS - the youngsters asked Shepherd about trash disposal and recycling aboard the ISS, procedures for dealing with a sick crew member and what the crew does for exercise. Near the conclusion of the contact, the students on hand hollered "73, Commander Shepherd!" in unison.

For more information on the ARISS program, visit the ARISS web site, http://ariss.gsfc.nasa.gov.

[ANS thanks ARISS and the ARRL for this information]

ANS in Brief

ANS news in brief this week includes the following:

Weekly Satellite Report

Link to the weekly report on satellite ...

All Satellites
ISS . Mir . 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 ans-editor@amsat.org, or to ANS Editor Dan James, NN0DJ, at nn0dj@amsat.org.

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This week's AMSAT News Service bulletins were edited by AMSAT  News Service editor Dan James, NN0DJ.

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