July 8, 2001

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AO-40 Update

The ARRL is reporting that AO-40's new orbit should be good for at least the next 20 years. The League based the story on information from AMSAT-DL President Peter Guelzow, DB2OS. Peter heads the satellite's ground control team. Following maneuvers to shift the satellite's orbit at perigee, AO-40 perigee now is "oscillating in a safe range between 810 and 1260 km," according to DB2OS.

AO-40's height at apogee of 58,971 km was unchanged by the orbital adjustment. The satellite's transponders remain off as ground controllers reorient the spacecraft.

Ground controllers were able to change AO-40's orbit through successive cold firings of the onboard arcjet motor, using only ammonia gas. The move raised AO-40 higher than predicted, and apparently depleted the spacecraft's ammonia supply. As a result, AO-40 likely will remain in its current orbit.

Stacey Mills, W4SM, of the ground team said it's "quite possible" that an ammonia leak accounted for the unexpected loss of ammonia. "If we did have a slow leak, it is very fortunate we did not wait any longer to use the remaining fuel," he said.

Mills said that AO-40's old orbital configuration, while stable, was too close for comfort at perigee.

"I sincerely hope that nothing else malfunctions for a long, long time, but this is, after all, rocket science," Mills said. "Nothing is guaranteed."

Ground controllers plan to fully test AO-40's momentum wheels prior to any decision to deploy the spacecraft's solar panels. The momentum wheels provide three-axis control of the spacecraft. If the momentum wheels are not operational, it's unlikely the solar panels will be deployed.

Stay tuned to ANS, the official source of AO-40 information.

[ANS thanks the ARRL for this information]

Predict Version 2.1.4 Released

John, KD2BD, has released an updated version of Predict, a popular satellite tracking and orbital prediction application for the Linux operating system. Predict version 2.1.4 includes the following changes from the previous version:

Best of all, Predict is free software!

The program can be found at

The Predict homepage is located at

[ANS thanks John Magliacane, KD2BD, 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 . 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, or to ANS Editor Dan James, NN0DJ, at

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