| Operator | University of Surrey[1] |
|---|---|
| COSPAR ID | 1984-021B[2] |
| SATCATno. | 14781 |
| Spacecraft properties | |
| Manufacturer | SSTL |
| Launch mass | 60 kilograms (130 lb) |
| Start of mission | |
| Launch date | 1 March 1984, 17:59 (1984-03-01UTC17:59Z) UTC |
| Rocket | Delta 3920 |
| Launch site | VandenbergSLC-2W |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Sun-synchronous |
| Inclination | 98.25 degrees |
UoSAT-2, which is also known asUO-11 andOSCAR-11, is a Britishsatellite orbiting inLow Earth Orbit. The satellite functions as anamateur radio 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 analogue telemetry channels failed in 2005, but as of 2014 the status channels were still operational.[3] The satellite was still heard transmitting telemetry in 2025, forty-one years after launch.[4]
It was operated bySurrey Satellite Technology Ltd.
The satellite was the second in the UoSAT series of satellites built by University of Surrey; preceded byUoSAT-1 and followed byUoSAT-3.
The satellite carries a Digitalkerspeech synthesiser,[5][6] magnetometers, a CCD camera, aGeiger-Müller tube, and a microphone to detect the vibrations ofmicrometeoroid impacts.[6] LikeUoSAT-1 it transmits telemetry data on theVHF beacon at 1200 baud, using asynchronousAFSK,[7] though now all analogue telemetry channels have failed;[8] on an FM receiver the audio signal resembles thecassette data format of the contemporaryBBC Micro computer.[6] Actually it is a BASICODE signal, but no citation. Slight modulation had also been observed on theS band beacon.[9]
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.[6]
The British affiliate ofAMSAT distributed a library of software for the BBC Micro to track UoSAT-2 and other satellites and analyse telemetry broadcasts.[10] A commercial fixed-frequency receiver,Astrid, was also produced by British firm MM Microwave[11] for the education market, with accompanying BBC Micro software to display raw telemetry frames. For versatility theAstrid set included a demodulator to load signals through theserial port of any computer.[6]
As it went around the Earth it encountered data upsets, geo-located around the South Atlantic anomaly.
According to a February 2008 status report the satellite had no viable battery backup, operating only from itssolar panels, and awatchdog 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 "permanenteclipses" in its orbit would begin in the middle of March 2008, limiting transmissions to "a short time, possibly less [than] a single orbit, every 21 days."[8] By April 2008 the updated prediction was that eclipses would continue until 2019.[12]
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.[10]
Current observation reports for UoSAT-2 can be viewed and logged at the Oscar Satellite Status Page.[13]
The satellite was instrumental in providing a communications link, known asNordski Comm, from theSki-Trek support teams to the expedition party. The position of the skiers' emergency beacon was calculated daily byCospas-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.[5][14]
Homepage DD1US / Sounds from Space] – Recordings of UO-11 speech and telemetry
