UoSAT-2, which is also known as UO-11 and OSCAR-11, is a British satellite orbiting in Low Earth Orbit. The satellite functions as an

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

transmitter (known as an OSCAR) and was built at the University of Surrey. It launched into orbit in March 1984 and remains orbital and active, though unstable with irregular periods of transmission. All of the Analog telemetry channels have failed, making telemetry from OSCAR 11 useless. The satellite was still heard transmitting telemetry in 2015, thirty years after launch. It was operated by Surrey Satellite Technology Ltd. (SSTL).

Characteristics

The satellite was the second in the UoSAT series of satellites built by University of Surrey; preceded by UoSAT-1 and followed by

UoSAT-3 UoSAT-3, also known as UO-14 and OSCAR-14, is a British satellite in Low Earth Orbit. It was built by a spin-off company of the University of Surrey, Surrey Satellite Technology (SSTL) and launched in January 1990 from French Guiana. The satellit ...

. The satellite carries a Digitalker

speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal languag ...

er, magnetometers, a CCD camera, a Geiger-Müller tube, and a microphone to detect the vibrations of

micrometeoroid A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface. The term "micrometeoroid ...

impacts. Like UoSAT-1 it transmits telemetry data on the

VHF Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF ...

beacon at 1200 baud, using asynchronous AFSK, though now all analogue telemetry channels have failed; on an FM receiver the audio signal resembles the cassette data format of the contemporary BBC Micro computer. Actually it is a BASICODE signal, but no citation. Slight modulation had also been observed on the

S band The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the convention ...

beacon. 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.

Support

The British affiliate of AMSAT distributed a library of software for the BBC Micro to track UoSAT-2 and other satellites and analyse telemetry broadcasts. A commercial fixed-frequency receiver, ''Astrid'', was also produced by British firm MM Microwave for the education market, with accompanying BBC Micro software to display raw telemetry frames. For versatility the ''Astrid'' set included a demodulator to load signals through the serial port of any computer.

South Atlantic anomaly

As it went around the earth it encountered data upsets, geo-located around the South Atlantic anomaly.

Status

According to a February 2008 status report the satellite had no viable battery backup, operating only from its

solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...

s, and a watchdog timer on board was 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, with the prediction that "permanent

eclipse An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ce ...

s" in its orbit would begin in the middle of March 2008, limiting transmissions to "a short time, possibly less hana single orbit, every 21 days." By April 2008 the updated prediction was that eclipses would continue until 2019. After a 21-month gap in observations, UoSAT-2 resumed sending telemetry sometime before 10 December 2009, and is apparently continuing the watchdog-controlled transmission regime, though now on a ten-days-on, ten-days-off schedule. Its condition has not otherwise improved apart from some recovery of battery power, allowing broadcasts to continue into each eclipse. Current observation reports for UoSAT-2 can be viewed and logged at the Oscar Satellite Status Page.

1988 Ski-Trek arctic expedition

The satellite was instrumental in providing a communications link, known as ''Nordski Comm'', from the Ski-Trek support teams to the expedition party. The position of the skiers' emergency beacon was calculated daily by Cospas-Sarsat ground stations and relayed to them, and thousands of amateur radio listeners, as a spoken message from the Digitalker on board UoSAT-2. The message could also serve as an emergency channel to the skiers in the event that all other radio links failed.

References

External links

AMSAT-UKTwenty years in space...
the UoSAT-2 launch video

– Recordings of UO-11 speech and telemetry {{Orbital launches in 1984 University of Surrey Satellites orbiting Earth Amateur radio satellites Satellites of the United Kingdom Spacecraft launched in 1984