Page 28 - EngineerIT October 2021

AMATEUR RADIO

UoSAT- 1: The satellite story of

ingenuity, teamwork and favours

October 2021 marked 40 years since UoSAT-1, designed and A DIY cleanroom
built by Martin Sweeting (now Sir Martin Sweeting) and a With the project well and truly off the starting blocks, Martin’s team
6 small team of research scientists at the University of Surrey, nipped down to the B&Q hardware store and bought 8’x4’ MDF boards
was launched on a Delta rocket from Vandenberg Air Force Base in and some plastic sheeting to rig up a cleanroom in the corner of
California. UoSAT-1 was the first modern microsatellite with in-orbit one of the University of Surrey’s research labs. A vacuum cleaner in
re-programmable computers and its signals were decoded and reverse-setting was used to pressurise the ‘cleanroom’ but, as Martin
analysed by thousands of radio amateurs, schools and universities recalled, the cleanliness of the set-up was called into question one
around the world. morning when the team arrived to find the satellite covered in tiny red
The story of Surrey Satellite Technology Ltd (SSTL’s) first satellite spider mites! There’s an intriguing possibility that one of these spiders
involves a huge amount of ingenuity, teamwork, calling in favours and could have survived hidden inside the satellite’s structure, and been
cheeky but successful requests for assistance! inadvertently launched into space!

Beginnings The satellite
The story starts in 1975 when a young Martin Sweeting was a UoSAT-1’s mission was research and education and the payloads on
student at the University of Surrey. Whilst studying for his PhD, the satellite included:
he developed an interest in amateur radio, and along with a group of • RCA 1802 and a Ferranti F100L microcomputers (16k RAM
like-minded friends, he started tracking Russian weather satellites reprogrammable in orbit)
using ham radio. • HF beacons on 7,14,21,28 MHz for ionospheric studies (3-metre
The weather and amateur radio satellites were initially tracked by deployable antennas)
hand until Martin managed to persuade the Royal Navy to donate a • 2GHz and 10GHz beacons 3-axis magnetometer, 20/40keV
gun carriage turntable that he arranged to have craned to the top of particle counters
the University’s BB building and voila! a cheap but effective satellite • Magnetorquers and a gravity gradient boom. VHF and UHF
tracking antenna was in operation! telemetry up/downlinks (AFSK-FM 75-1200bps, RTTY, Morse
From these beginnings, Martin formed the idea of building code, ‘DIGITALKER’ digitised voice)
his own small satellite and led the small team to design and • CCD array camera (256x256 pixels, GSD ~2km)
build UoSAT-1. The effort was helped along the way by support
in advice, components and facilities donated from AMSAT (the The satellite was entirely hand-built, with some of the design work
Amateur Radio Satellite Corporation in the USA, Germany, taking place on kitchen tables as the project progressed over long
Hungary), various companies and government research labs, hours. The power conditioning system was contributed by AMSAT who
but also some essential funds supported by Ralph Benjamin, a also were key in arranging a launch on a US rocket.
visiting professor at the University of Surrey and director at GCHQ
(a world-leading intelligence, cyber and security agency with a A DIY vibration testing campaign
mission to keep the UK safe). The engineering model for UoSAT-1 was vibration-tested in a typically
low cost and pragmatic process which involved putting it in the boot
of Martin’s car, pumping up the tyres, and driving it up and down
Guildford’s historic cobbled High Street a few times.

UoSAT-1 cleanroom at the University of Surrey UoSAT-1 operations computer

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