UO-11
Encyclopedia
UO-11 is an amateur satellite
built at the University of Surrey
and launched into orbit on 1 March 1984. It remains orbital and active, though unstable with irregular periods of transmission. The satellite was still heard transmitting telemetry in December 2010, more than twenty-six years after launch. It transmits a beacon at 145.826 MHz, with inactive beacons at 435.025 MHz and 2401.5 MHz.
It is operated by Surrey Satellite Technology Ltd
(SSTL), who also build UoSATs.
er, magnetometers, a CCD camera, a Geiger-Müller tube
, and a microphone to detect the vibrations of micrometeoroid
impacts. Like UoSAT-1
it transmits telemetry data on the 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. Slight modulation had also been observed on the S band
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.
distributed a library of software for the BBC Micro to track UO-11 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.
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: since the middle of March 2008 there have been eclipse
s in its orbit which will continue "permanently", limiting transmissions to "a short time, possibly less [than] a single orbit, every 21 days." The eclipses are now expected to continue until 2019.
After a 21-month gap in observations, UO-11 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 UO-11 can be viewed and logged at the Oscar Satellite Status Page.
ground stations and relayed to them, and thousands of amateur radio listeners, as a spoken message from the Digitalker on board UO-11. The message could also serve as an emergency channel to the skiers in the event that all other radio links failed.
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
built at the University of Surrey
University of Surrey
The University of Surrey is a university located within the county town of Guildford, Surrey in the South East of England. It received its charter on 9 September 1966, and was previously situated near Battersea Park in south-west London. The institution was known as Battersea College of Technology...
and launched into orbit on 1 March 1984. It remains orbital and active, though unstable with irregular periods of transmission. The satellite was still heard transmitting telemetry in December 2010, more than twenty-six years after launch. It transmits a beacon at 145.826 MHz, with inactive beacons at 435.025 MHz and 2401.5 MHz.
It is operated by Surrey Satellite Technology Ltd
Surrey Satellite Technology Ltd
Surrey Satellite Technology Ltd, or SSTL, is a spin-off company of the University of Surrey, now fully owned by EADS Astrium, that builds and operates small satellites. Its satellites began as amateur radio satellites known by the UoSAT name or by an OSCAR designation...
(SSTL), who also build UoSATs.
Characteristics
The satellite carries a Digitalker speech synthesisSpeech 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...
er, magnetometers, a CCD camera, a Geiger-Müller tube
Geiger-Müller tube
A Geiger–Müller tube is the sensing element of a Geiger counter instrument that can detect a single particle of ionizing radiation, and typically produce an audible click for each. It was named for Hans Geiger who invented the device in 1908, and Walther Müller who collaborated with Geiger in...
, and a microphone to detect the vibrations of micrometeoroid
Micrometeoroid
A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. A micrometeor or micrometeorite is such a particle that enters the Earth's atmosphere or falls to Earth.-Scientific interest:...
impacts. Like UoSAT-1
UoSat-OSCAR 9
UO-9 was an amateur satellite built at the University of Surrey and launched into low Earth orbit on 6 October 1981. It exceeded its anticipated two-year orbital lifespan by six years, being received on 13 October 1989 before re-entering the atmosphere...
it transmits telemetry data on the 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
BBC Micro
The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...
computer. Slight modulation had also been observed on the S band
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...
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 AMSATAMSAT
AMSAT is a name for amateur radio satellite organizations worldwide, but in particular the Radio Amateur Satellite Corporation with headquarters at Silver Spring, Maryland, near Washington DC. AMSAT organizations design, build, arrange launches for, and then operate satellites carrying amateur...
distributed a library of software for the BBC Micro to track UO-11 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
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
of any computer.
Status
According to a February 2008 status report the satellite had no viable battery backup, operating only from its solar panelPhotovoltaic module
A solar panel is a packaged, connected assembly of solar cells, also known as photovoltaic cells...
s, and a watchdog timer
Watchdog timer
A watchdog timer is a computer hardware or software timer that triggers a system reset or other corrective action if the main program, due to some fault condition, such as a hang, neglects to regularly service the watchdog A watchdog timer (or computer operating properly (COP) timer) is a computer...
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: since the middle of March 2008 there have been eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...
s in its orbit which will continue "permanently", limiting transmissions to "a short time, possibly less [than] a single orbit, every 21 days." The eclipses are now expected to continue until 2019.
After a 21-month gap in observations, UO-11 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 UO-11 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-SarsatCospas-Sarsat
Cospas-Sarsat is an international satellite-based search and rescue distress alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. It is best known as the system that detects and locates emergency beacons...
ground stations and relayed to them, and thousands of amateur radio listeners, as a spoken message from the Digitalker on board UO-11. The message could also serve as an emergency channel to the skiers in the event that all other radio links failed.
External links
- AMSAT-UK
- Twenty years in space... the UoSAT-2 launch video
- Homepage DD1US / Sounds from Space – Recordings of UO-11 speech and telemetry