I år är det 30 år sedan satelliten UoSAT-2 (OSCAR 11) kom upp grattis! Läs mer:
UoSAT-2 was launched on March 1st, 1984, from Vandenberg Air Force
Base in the USA and carried some novel payloads, including a
“Digitalker”.
Today, UoSAT-2 still transmits its VHF telemetry on a regular 11-day
cycle, although the satellite’s batteries are exhausted after some
160,000 charge cycles and transmissions are now detectable only when
it is in sunlight. However, the telemetry continues to be tracked by
amateur radio satellite enthusiasts worldwide, using the predictable
transmissions to help calibrate their equipment.
Following the successful first microsatellite launch of UoSAT-1 from
the Surrey team in 1981, NASA again offered a second launch
opportunity—but with only 6 months warning! Rising to the challenge
and literally working day-and-night, the Surrey team comprising about
a dozen researchers and AMSAT members designed and built the 70kg
UoSAT-2 microsatellite just in time for the launch as a ‘piggyback’
passenger with NASA’s LANDSAT-5. Incorporating many of the lessons
learned from their first satellite, UoSAT-2 carried some novel
experiments – a “Digitalker” speech synthesizer, specifically
designed for school demonstrations of satellite telemetry and orbital
physics, alongside experiments including magnetometers, an early CCD
camera, a Geiger tube and a sensitive microphone to detect micro-
meteoroid impacts.
In the days before GPS, UoSAT-2 provided a novel communication
system for the 1988 Canadian-Soviet Ski-trek arctic expedition, a
group of intrepid explorers from Canada and the USSR who crossed the
Arctic Ocean from Siberia to Ward Hunt Island, just off Canada, via
the North Pole between March and June 1988. The position of the
skiers’ emergency beacon was calculated daily by US and Soviet COSPAS-
SARSAT ground stations, relayed to the Surrey Mission Control
Groundstation by telex, and uploaded to the UoSAT-2 Digitalker which
then ‘spoke’ the latitude and longitude of the ski party via its VHF
beacon. In a sun-synchronous, 650km low Earth orbit, UoSAT-2 flew
over the pole every 98 minutes at which point the group could receive
the broadcast from the satellite using their small handheld VHF
radios that were designed to work at very low temperatures. The
Digitalker communications system could also serve as an emergency
channel in the event that all other radio links failed. Thousands of
amateur radio listeners and schoolchildren also monitored the spoken
messages from the Digitalker and plotted the path of the expedition –
many using the then state-of-the-art BBC microcomputer! There’s more
about the Ski-trek expedition, and a recording of the Digitalker, on
the expedition home page at
http://www.meerman.fsnet.co.uk/NorthPole/textpan.html
UoSAT-2 was one of the first satellites to prove that commercial
grade microprocessors and memory chips, which had only just become
readily available, mass produced and cheaper in the early 80s as part
of the microcomputer revolution, could be used to build small, cost-
effective yet capable satellites. The idea of taking advantage of
commercially available technology and adapting it for space, instead
of using expensive ‘space-grade’ components, was virtually unheard of
at the time, but SSTL proved the concept was viable and has gone on
to build a highly successful business.
Today, UoSAT-2 is the longest-serving of 13 satellites that SSTL and
the Surrey Space Centre track from ground stations in Guildford, UK.
SSTL and the Surrey Space Centre have come very long way from those
early days of the 1980s!
The SSTL infosite may be accessed at
[ANS thanks SatNews Daily and AMSAT-UK for the above information]