A hugely successful and largely unsung British space programme is about to draw to a close with the final launch of a Skylark sounding rocket.
The vehicle, which first flew in 1957, became a very inexpensive but effective way of carrying scientific experiments into suborbital space.
It lost official UK government support in the late 1970s but sufficient motors were left to continue research flights.
The 441st and last Skylark will blast off from Sweden on Sunday.
The launch window at the Swedish Space Corporation's Esrange site, near Kiruna, opens at 0600 BST (0700 CEST).
Hugh Whitfield, of Sounding Rocket Services Ltd, which has operated the Skylark vehicles since 1999, told the BBC News Website: "This is a 50-year-old programme - it began in 1955 and we will conclude in 2005. At one stage, it was a very big programme with over 200 people working on it.
"The Skylark is a classic. Back in the '50s, Britain was very advanced on the capabilities of aircraft and they were coming up to launch satellites; the country was Europe's leading light and we were up there with the Americans and Russians.
"It wasn't until later in the '50s and '60s that governments started cutting back on programmes."
The final mission, Maser 10 as it is known, has been organised under the European Space Agency banner, and will carry five experiments.
They include a biological investigation of the muscle protein actin, and a study of turbulence in evaporating liquids.
The tests will experience about six minutes of "weightlessness", allowing their scientists to examine the physical processes at play that would otherwise be masked by the effects of gravity in a surface laboratory.
The Maser 10 payload will be recovered by helicopter after it has parachuted back to Earth.
The final Skylark rocket will carry five experiments
Early development work on Skylark was done at the Royal Aeronautical Establishment at Farnborough and the Rocket Propulsion Establishment at Westcott.
The vehicle made its maiden flight in the International Geophysical Year, at Woomera, in Australia - where many British rockets were tested in the days when the UK had serious launch ambitions of its own.
The rockets became very popular with young scientific researchers, as it was possible for a PhD student to design a space experiment, launch it on a Skylark vehicle and then write up the results in just three years.
"The main thing it has given is a lot of experience for engineers and scientists who have gone on to bigger and better things," commented John Turner, a design engineer who worked on Skylark from the mid-'60s. "It was the place where people cut their teeth in aerospace."
All manner of investigations have been done on Skylarks: from X-ray astronomy to crystal growth, from Earth-observation to the study of how frogs eggs are fertilised.
But despite its success, the UK government ended public funding for the programme in 1977. The expectation was that university departments would want to fly their experiments on the soon-to-launch American space shuttle instead.
At that time, it was anticipated the new US orbiter would make frequent trips into space, giving researchers ample space and opportunity to run their tests under much longer conditions of microgravity.
The Skylark 7 will take its payload to an apogee of 250km
"It would be very nice if Britain could compete in the space race, but we are now just a bit player in a European agency. We could have been there, but we let the opportunity go," said Mr Whitfield.
The Skylark programme has persisted despite being shoved from one home to the next.
The commercial operation was initially handed to British Aerospace, then to Matra Marconi Space, before finally coming out into the small, privately run Sounding Rocket Services company based in Fishponds, Bristol.
The first Skylark was capable of lifting 45kg to 150km. The final variant, Skylark 12, could carry a 200kg payload to 576km.
"The 12 was a three-stage vehicle and was the most powerful in the series," explained Mr Whitfield.
"We actually did a launch in Brazil which reached an apogee of 1,000km. It was a light payload, mind; a German experiment to look at a Southern Hemisphere aurora."
The Skylark 7 that will be used for the final launch will take its payload to an apogee of 250km. It will be powered by a "Raven XI" main-stage and a "Goldfinch" boost-stage motor.
SRS will in future launch the American-built Oriole range of sounding rockets. The Oriole is a slightly larger rocket than the Skylark and its newer design offers greater capability despite being more expensive.