Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!genrad!decvax!harpo!eagle!karn
From: karn@eagle.UUCP
Newsgroups: net.ham-radio
Subject: Oscar-10 update
Message-ID: <1019@eagle.UUCP>
Date: Sat, 25-Jun-83 03:53:14 EDT
Article-I.D.: eagle.1019
Posted: Sat Jun 25 03:53:14 1983
Date-Received: Sat, 25-Jun-83 21:59:07 EDT
Lines: 40

As expected, the sun sensors on AMSAT-OSCAR-10 are now beginning to
function.  Yesterday, initial data from the sensors indicated that the
spin is very low, less than the 2 RPM lower limit at which the spin
rate determination system will function properly.  This spin rate was
consistent with observed regular fades due to the side lobes of the
off-pointed hi-gain antennas.

It was also determined that the spacecraft is apparently spinning slowly
BACKWARDS from the direction it should have been spun by the Ariane. 
This now points to an explanation in which the Ariane either did not
give us the correct spin rate or did not spin us up at all.

In any case, software has been loaded to spin up the satellite (in the
"backwards" direction so as to avoid going through a zero spin rate)
and should execute on the upcoming perigee pass about an hour from now.

Spacecraft systems continue to function quite well, and there is now
plenty of power from the solar arrays due to the improved sun angle. 
Here is a CW telemetry frame just copied from the 145.810 mhz general beacon:

AMSAT OSCAR 10 at 03:30:00 UTC Orbit 19 MA 216/256 TLM: UBAT 14.5 V
TBAT 4.9C Iarray 0.4A SA 0.2 dg Spin 2 RPM Satellite status:
First motor firing and orbit change delayed to orbit 50 because
orientation change required transponder off until then listen to this
bulletin on the hour for latest news AMSAT OSCAR 10 HI HI

Comments: Solar array current has not risen because there is already
enough current for the spacecraft systems and the battery is fully
charged; therefore the battery charge regulator has cut back the operating
point of the solar arrays, reducing the generated current.  The battery
voltage is lower than it was during the first few days of the mission
because the NiCds have a negative temperature coefficient; a fully
charged battery has a higher open circuit voltage at lower temperatures.

"MA 216/256" (MA = "Mean Anomaly") means that the satellite has
completed 216/256 of its orbital period; perigee is defined as MA = 0,
and apogee is 128.  The SA (sun angle) and Spin figures are still
wrong because of the very slow spin rate.

Phil Karn, KA9Q/2