JAMSAT 日本アマチュア衛星通信協会


To: amsat-bb@AMSAT.Org
Date: Fri, 26 Feb 1999 18:27:11 -0000
From: "Dennis Ray Wingo" <>
Subject: [jamsat-amsat-bb:22899] SEDSAT Status 2-26-99

I have been working with the SEDSAT numbers that Mr. John Simon has been providing us and some interesting facts have come out. The satellite is waaay power positive right now with a max solar array power, averaged over all faces of 24.7 watts. This is over the theoretical maximum. How is this so? Well, in looking at the power numbers since launch it seems that when the satellite is in its most favorable day/night geometry like now, there is a significant contribution (2-5 watts) from the Earth's albedo. This was not predicted and is a welcome help to the power budget.

The satellite has been active for over four months now!!! The stated minimum design life of SEDSAT that we wanted was six months. It is just too bad the problems with the receivers or we would have such a beautiful bird. However, the engineering telemetry from the satellite is verifying our design choices waaay back in the beginning of the design. The temperature deltas are all less than five degrees C per orbit and only about 10C per min/max sun cycle. This is a wonderful thing in that wide temperature variations are one of the primary reasons for on orbit failures of satellite systems.

Also, I think that I have finally figured out which arrays are swapped in the telemetry file. It is the -X face and the -Y face. The currents, averaged over long periods confirm closely to the measured flash data that Ted Edge did for us at the NASA MSFC SunSpot chamber.

Again, in my opinion we can claim now at least partial victory for our satellite. Most of the engineering goals have been met, it is just a total shame that the imaging system has not been able to fulfill its mission due to the probable loss of both receivers. However, Chris Bond and co have set up the UAH ground station finally and maybe with the reset box we can figure out if either one of them are functional at all.

Dennis Ray Wingo

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to