Live long, Prospero Bristol’s part in space triumph
Fifty years ago Bristol’s space engineers scored a great success when the first British-made satellite was put into orbit on a British-made rocket – despite the fact that they knew they would have to find new jobs straight afterwards. Retired aerospace en
FIFTY years ago, Bristol space engineers played a key role when Britain’s first satellite to be launched on a British rocket was sent into orbit around the Earth. Not the first British satellite, and not the first rocket, but the first time both satellite and rocket combined were British.
The satellite, known only as X3 up to the final countdown, but renamed Prospero once in orbit, had been built at the Filton works of the (then) British Aircraft Corporation.
The rocket that launched it was the Black Arrow; the launch site was Woomera in the Australian
Outback, and the date was October 28, 1971.
It was a tense and nervous, but dedicated, team from Britain and Australia that worked for many weeks towards the moment of liftoff. Tense and nervous, because three previous test flights of the Black Arrow launcher had failed to achieve their objectives.
The first two attempts did not carry spacecraft but were only to prove the first and second stages of the rocket – but both failed. The third attempt carried a simple satellite named Orba, which never made it into orbit but fell into the ocean off the north coast of Australia.
And dedicated – many people had worked long and hard together to get their spacecraft into orbit, but as the launch day approached, they learned that the whole Black Arrow project had been cancelled by the UK Government.
There would be no more Britishmade launchers; future satellites would be launched on American rockets. But the team’s dedication shone through – they had been given the opportunity to complete the Prospero mission knowing that they would need to find new jobs when they returned home. They were determined to get it right. And they did.
Fifty minutes after lift-off, a NASA tracking station in Alaska reported “we have an operational 137MHz signal passing overhead”. In other words, “there’s a satellite transmitting data on the right frequency just gone over us”. Prospero was in orbit – and working.
Compared to modern spacecraft, Prospero was small, weighing only 65kg, and contained a number of relatively simple experiments, primarily to evaluate new technologies for use in future space missions. There were different types of solar cells, innovative, lightweight electronic components and various surface coatings to see how they could control temperatures.
Then there was a meteorite detector provided by scientists at the University of Birmingham – to count the number of dust impacts encountered in space.
But all that data was to prove highly important to the design of later spacecraft designed at Filton and elsewhere – for customers worldwide.
So what happened to Prospero? Prospero is still in orbit! That orbit is in fact an ellipse, an ovalshaped orbit ranging from 534km at the closest point to Earth, and 1,314km at the furthest. It’s inclined at 82 degrees to the equator, meaning it gets almost to the north and south poles before crossing the equator on the way up, and on the way down. It takes 103 minutes to complete one orbit.
Unfortunately, Prospero’s tape recorders stopped working after two years, meaning that data could not be stored for later transmission to the ground. But by calling on ground stations around the world, data could still be received.
Prospero was officially deactivated in 1996 (when the ground station collecting data was closed down) but a radio signal could still be detected in 2004.
Prospero is expected to remain in orbit until about 2070 before falling back to Earth and burning up in the atmosphere – give or take that’s 100 years after launch.
Until then, you can see where Prospero is at any time by following the following weblink: www.n2yo. com/?s=5580
That’s not all that happened in 1971. At the same time as Prospero was being built, Bristol’s satellite engineers at BAC were also working to prepare another satellite,
Ariel 4, for launch.
Whereas Prospero was designed to evaluate new technologies, Ariel 4 would carry out scientific investigations of the Earth’s magnetosphere – the magnetic radiation fields surrounding the Earth, and the high energy charged particles arriving from the Sun.
Ariel 4 was the British Aircraft Corporation’s first ‘Prime Contract’ for a satellite – which meant that the company was responsible for all project management and procurement of component parts.
Ariel 4 would be launched just over six weeks after Prospero, on December 11, 1971 – also 50 years ago this year. This launch was aboard an American Scout launch vehicle, from the Vandenberg launch site in California. The spacecraft operated successfully for seven years and a day, burning up in the Earth’s atmosphere on December 12, 1978.
Do we detect a bit of theatre in the naming of these satellites? Yes, spacecraft names do sometimes follow unexpected patterns. Ariel is a spirit who appears in William Shakespeare’s play The Tempest. Ariel is bound to serve the magician Prospero, who used magic to rescue him from a tree in which he had been imprisoned by the witch, Sycorax.
And in a follow-on to Prospero, the next technology-development spacecraft launched by an American rocket in 1974 was named Miranda – after Prospero’s daughter.
There were lots more. Prospero and Ariel set the scene for over 20 more years of spacecraft development at Filton, known initially as Bristol Aircraft Corporation and British Aircraft Corporation, but then British Aerospace – until the Space Systems division was sold to Matra Marconi Space.
Space work was relocated to Stevenage and Portsmouth in 1999 but over that time, Filton’s engineers, project managers and technicians contributed hardware and expertise to 62 different satellites. Only four failed to reach orbit when their launch vehicle exploded. Even now, 43 of them are still in orbit – 40 around the Earth and three around the Sun. And seven are still operating.
Terry Ransome was a Spacecraft Assembly Integration and Test Engineer/Manager from 1971 to 2003, at Filton, Bristol until 1999, then Stevenage, Hertfordshire until retirement in 2003. He currently lives in Nailsea, North Somerset and is a Collections Research Volunteer at Aerospace Bristol.
He is available for talks – see https://www.publicspeakerscorner. co.uk/terry-ransome
Tel: 01275 858254/07813 262045 or email rocketfella@btinternet.com or t.ransome2016@btinternet.com