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Cover story.qxd 2/5/07 4:59 pm Page 14 An Ariel view of UK spacecraft It’s 40 years since t was 5 May 1967, just before 12pm, when a satellite was designed by the Space Scout rocket was launched from NASA’s West- Department of the Royal Aircraft Estab- the first UK designed and I ern Test Range in California, witnessed by a lishment (RAE), Farnborough, with group of British scientists and engineers wit- British Aircraft Corporation and GEC as manufactured satellite nessed. The successful launch assured the precious the main industrial contractors. cargo – and the engineers – a place in UK engi- At the time, relatively little was known was launched. How has neering history. about the space environment, although Sitting atop the four stage Scout was Ariel III the RAE did simulate vacuum, radiation – the first entirely UK built satellite and third in and thermal effects on Ariel and its pay- the UK satellite industry an Anglo-American cooperative space research load. Meanwhile, thanks to the RAE’s SkyLark programme to extend atmospheric and ionos- rockets, which had been providing upper atmos- developed? pheric investigations. The small observatory car- phere research data since 1957, many of the test ried five British experiments and a tape recorder payloads used by Ariel had been proved in rocket Vanessa Knivett to obtain data. launch and simply required adaptation. Sputnik 1, the first man made satellite, had Ariel III was approximately 66in high and 30in explores. been launched almost 10 years earlier, on 4 Octo- in diameter. Four booms hinged out from the ber 1957. Viewed more as a show of political lower part of the body, carrying two loop aerials for might than of scientific worth, the mission never- galactic noise and very low frequency experiments, theless kickstarted space exploration and the UK, plus electron density and temperature sensors. On thanks to its burgeoning aerospace and defence either side of the booms and on the satellite’s cylin- sectors, had the skill and expertise to participate. drical surface were some 8000 solar cells, provid- The Ariel programme began in April 1962 ing an estimated 10W yield if the satellite was spin under the guidance of the British National Com- stabilised or tumbling, or 100W if sun stabilised. mittee on Space Research. Ariel 1, the first of the The satellite weighed 68kg and included 3000 six missions, was built at NASA’s Goddard Space electronic components – mostly discretes, Flight Center, although the six experiments although transistors had just replaced thermionic The British Interplanetary Society (BIS) aboard were British. By contrast, the third Ariel valves. Data was sampled in real time at about 14 New Electronics www.newelectronics.co.uk 8 May 2007 Cover story.qxd 2/5/07 5:00 pm Page 15 40 YEARS OF UK SATELLITES COVER STORY 50Hz, with sampling rate for recorded data at EADS Astrium is also the prime system inte- 1Hz. Ariel III’s life expectancy was one year, grator for the Laser Interferometer Space Antenna although it continued to orbit for about two years (LISA) Pathfinder mission, planned for launch in and was eventually turned off in September 1969. 2009 and on which Warren is currently working. Whilst the UK had its own satellite launch LISA’s goal is to detect and observe gravita- technology, the US provided the launch vehicle. tional waves from black holes and galactic bina- The UK’s launcher was Black Prince, a peaceful ries, as part of a joint ESA/NASA initiative called reincarnation of the cancelled Blue Streak ballistic ‘Beyond Einstein’. The experiment consists of missile programme, plus the Black Knight launch three spacecraft, each containing two free floating vehicle, redesigned for satellite launch purposes as ‘proof masses’. Laser interferometry will be used Black Arrow. Black Arrow was used for Britain’s to detect the small vibrations in the proof masses only indigenous satellite launch, Prospero X-3, on caused by gravitational waves. Amongst the chal- 28 October 1971, but was then retired. lenges facing the engineering team is to detect the At one time, the UK had a space programme to distance shift caused by gravitational waves, all rival the US and Russia, but the costs were deemed other sources of vibration must be eliminated or politically unsound. One by one, projects were damped down. A very quiet design is needed, as cancelled and the UK became a founder member well as compensation for buffeting by solar wind of the European Space Agency (ESA) in 1975. and the correction of minute orbital changes introduced by solar radiation pressure. Small is beautiful It’s a far cry from Ariel, but there are some Above: A model of Ariel 1 Significantly, Ariel was a small, lightweight space common engineering issues. A challenge for hangs in the Royal Society’s mission and early communications satellites were today’s satellite designers is that it is small com- London headquarters. Built by designed with the same mindset. For example, the pared to consumer electronics and there is little Westinghouse in the US, the first commercial satellite IntelSat I (known also as incentive for ic manufacturers to develop radia- satellite was launched in 1962. Early Bird) measured 76 x 61cm and weighed tion hardened parts for space applications. Centre: Ariel-4 was built by the 34.5kg. Launched on 6 April 1965 to han- Warren notes that engineers in the 1950s would British Aircraft Corporation and dle line of sight communications between also have had to make best use of readily available launched in 1971. Ariel-6, the Europe and North America, it could relay technology. Referring to the still evolving body of last satellite in the series, was 240 voice circuits or one tv channel. knowledge relating to radiation belts in Ariel’s launched in 1979. However, the race to land a man on the Moon brought large scale missions. In 1968, NASA launched the second of its Orbiting Astronomical Observatory satel- lites, carrying 11 ultraviolet telescopes. The launcher was an Atlas-Centaur rocket, what was to prove a long serving NASA workhorse. With heavier payloads now possible, the number and size of satellite missions expanded dramatically. Communications has proved a key market, although many scientific investigation, Earth obser- vation, weather, navigation and military missions have now been accomplished. Today’s telecommunications satellites look vastly different to Early Bird. Inmarsat 4, for exam- The British Interplanetary Society (BIS) ple, weighs 6.5tonne and provides time, he says: “Ariel’s components Above: Surrey Satellite 240 channels, capable of routing were larger and therefore less sus- Technology built CFESat in 27 tens of thousands of phonecalls. ceptible to the effects of radiation months, based on existing Comments Carl Warren, a mis- than the tiny transistors of today, designs from its disaster sion system engineer for EADS but the engineers would have monitoring constellation and Astrium, which built Inmarsat 4: relied upon best estimates, which TopSat mission. “Processing power is at the heart meant conservative shielding and Left: Nigeriasat-1, also built by of Inmarsat 4’s capabilities, therefore excess weight. Nowa- SST, is part of a Disaster although boundaries are being days, we can perform detailed Management Constellation of pushed elsewhere in today’s satel- radiation analysis on each part satellites. lite designs.” and the system as a whole. We test New Electronics www.newelectronics.co.uk 8 May 2007 15 Cover story.qxd 2/5/07 5:01 pm Page 16 40 YEARS OF UK SATELLITES COVER STORY parts comprehensively and pro- Looking back, da Silva Curiel vide just the appropriate shield- says the West’s limited ing. At a system level, we take a launcher capability forced its redundancy approach. For satellite engineers to innovate. example, we might decide to Nowadays, it is pressure to run systems in parallel, such as reduce the cost of entry to three sensors that are triple space that is guiding its future majority voted, so the other two and one way of achieving this are relied upon when one fails.” is to make satellites smaller and cheaper to launch. Ringing the changes SST remains closely linked with Early satellite designs highlight the University of Surrey’s Space the technological evolution. Centre research department, Notes Warren: “In the 1960s, from which it spun out. In the early solar cells were very inef- mid 1990s, head of the Univer- ficient – nowadays, we are sity’s Planetary Environments using GaAs and achieving effi- Group Dr Craig Underwood ciencies of around 30%.” set his students the challenge of In Ariel III, attitude and building a nanosatellite of 10kg spin were monitored by onboard sun sensors and or less. The result was SNAP, which at 6.5kg could by optical observations of solar reflection from a sit on a dinner plate and yet comprised three pay- series of six mirrors mounted near the satellite loads and a propulsion system the size of a pencil. Above right: equator. Warren says sun sensors are still used, but Designed to demonstrate the capabilities of EAD Astrium’s Inmarsat 4 the primary source of location information comes nanosatellites as autonomous robots for observ- weighs 6.5tonne. With 240 from highly accurate CCD based star trackers. A ing orbiting space vehicles, SNAP-1 was built by channels, it can route tens of gyroscope is also employed to sense rate and rota- SST and launched alongside the Chinese thousands of phonecalls. tional changes, notably employing a ring laser as Tsinghua-1 microsatellite in June 2000. Now, Dr Below: EADS Astrium is the opposed to a mechanical version. Indeed, where Underwood’s students are developing a pico- prime system integrator for the possible, mechanical systems are avoided as these satellite (sub 1kg) called PALMSAT.