UO-11

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Launch
UoSAT-OSCAR 11
Date	March 1, 1984
Vehicle	Thor Delta 3920
Site	Vandenberg AFB, Lompoc, CA USA
Orbit characteristics
Type	Sun-synchronous orbit
Altitude	697 km (433 mi)
Inclination	98.25°
Mass	60 kg (130 lb)

UO-11 (aka UoSAT-OSCAR 11, AMSAT OSCAR-11, UoSAT-2 or UoSAT-B) is an amateur satellite built at the University of Surrey and launched into orbit on March 1, 1984. It is still orbital and active as of 2008, twenty-four years after its launch. It transmits a beacon at 145.826MHz, with inactive beacons at 435.025MHz and 2401.5MHz.

It is operated by Surrey Satellite Technology Ltd, who also build UoSATs.

The satellite carries experiments including magnetometers, a CCD camera, a Geiger-Müller tube, and a microphone to detect micrometeoroid impacts. Like UoSAT-1^[1] it transmits telemetry data on the VHF beacon at 1200 baud using asynchronous AFSK,^[2] though now only the digital status fields are valid;^[3] in FM mode the audio signal resembles the cassette data format of the contemporary BBC Micro.^[1] This was the basis of the Astrid package sold by British firm MM Microware, consisting of a fixed frequency VHF receiver set and software for the BBC Micro to interpret the telemetry frames, although they were read in through the serial port instead of the cassette port. Slight modulation had also been observed on the S band beacon.^[4]

According to a February 2008 status report the satellite has no viable battery backup, operating only from its solar panels, and a watchdog timer on board is suspending activity for up to three weeks following any power anomaly. At the time of the report it was experiencing continuous sunlight for the last time; since the middle of March 2008 there have been eclipses in its orbit which will continue "permanently", limiting transmissions to "a short time, possibly less [than] a single orbit, every 21 days."^[3]

UoSAT-2's solar arrays were bought at a premium compared to those of UoSAT-1, the design having been space tested by its predecessor.^[1]

[edit] References

^ ^a ^b ^c Cook, Mike (June 1986). "Way into the world of satellite telemetry: Mike Cook reviews the Astrid telemetry package". The Micro User 4 (4): 152. Stockport, UK: Database Publications. ISSN 0265-4040.
^ Amateur Satellite Summary - UoSAT-OSCAR-11. AMSAT (2003-05-31). Retrieved on 2008-02-24.
^ ^a ^b Wallis, Clive (2008-02-17). OSCAR-11 Report: 2008-02. AMSAT-UK. Retrieved on 2008-02-23.
^ Wallis, Clive (2008-01-26). OSCAR-11 Satellite. Retrieved on 2008-02-23.