The capsule claimed the life of the first astronaut to fly in it and was later involved in one of the worst accidents in spaceflight history. Yet Soyuz – which was first blasted into space 50 years ago – has since become the most successful craft to carry humans into Earth orbit. It is the workhorse spaceship on which manned missions beyond the atmosphere are now completely reliant.

Soyuz took the first earthlings – a cage of tortoises – to the moon in 1968, carried Britain’s only two astronauts, Helen Sharman and Tim Peake, into space, has been used for well over 100 manned space missions and has since become the only craft capable of ferrying astronauts to the International Space Station. For an ageing piece of cold war technology, the spaceship has earned itself a remarkable reputation and has seen off far more complex, expensive craft such as the space shuttle, which was retired by Nasa five years ago.

But the future of Soyuz is in question today. Some experts believe that the craft will soon be replaced by cheaper spaceships now being developed in the US by Elon Musk and other entrepreneurs. Others expect that Soyuz will still be flying for years to come. “Soyuz is certainly not done yet,” said former Nasa engineer David Baker, editor of the UK journal Spaceflight and author of Soyuz: An Owner’s Workshop Manual, published by Haynes. “It could easily be in use in years to come.”

Facebook Twitter Pinterest British astronaut Helen Sharman after a successful space flight in Soyuz. Photograph: Alamy

Sharman – who flew to and from the Mir space station in 1991 in the spacecraft – described flying on Soyuz as an unforgettable experience. “You can feel things clunking into place when you push buttons on the control panel. You can hear valves opening and shutting. It is solid, reliable and robust. After all, it had to withstand conditions at the Soviet launch site in Kazakhstan where temperatures drop to minus 30C in winter and reach plus 30C in summer. That is why it is still in use today.”

The basic design for Soyuz was established in 1962 by the Soviet rocket engineer Sergei Korolev. The craft was intended to become the spaceship that would carry Soviet cosmonauts to the moon. (A separate lander would ferry one person to the lunar surface.) On 28 November 1966, an unmanned version was launched with the aim of carrying out a rendezvous with a second Soyuz to be launched next day. However, the craft’s systems failed within minutes of reaching orbit and the mission was abandoned. A follow-up mission ended in disaster when its launcher exploded on the launchpad, killing one person.

Facebook Twitter Pinterest Soviet cosmonaut Vladimir Komarov died in the first manned Soyuz mission in 1967. Photograph: SVF2/UIG via Getty Images

The Soviets pressed ahead and in April 1967 the first manned Soyuz was launched but crashed on re-entry when its descent capsule’s parachute failed to open, killing its only crewman, Vladimir Komarov. Flights resumed 18 months later and Soyuz eventually entered regular service, though by then the Soviets were lagging behind America in the race to the moon. Nevertheless they were still able to come up with one startling mission using a version of Soyuz, called Zond 5.

“They put a small cargo of tortoises on board – as well as some seeds, worms and flies – and sent it to the moon,” said Doug Millard, curator of a recent exhibition, Cosmonauts, at the Science Museum in London. “It flew round the moon and headed back to Earth. The craft was recovered and the tortoises survived. These were the first animals to be sent to the moon, it transpires.”

Zond 5 flew in September 1968. After its success, cosmonaut Alexei Leonov pressed to follow immediately on a similar mission – to circle the moon and return to Earth – and so beat America which was planning its own circumlunar mission, Apollo 8, that December. “Leonov was refused permission and so America got to the moon first – though they did not land until Apollo 11 touched down on the lunar surface in July 1969,” added Baker. “At the end of the day, the Russians were just more cautious.”

After losing the race to the moon, Russia concentrated on Earth orbit missions and the construction of manned space stations. Soyuz became the workhorse for those missions though it suffered one more tragic failure when the three crew members on board Soyuz 11 – Georgy Dobrovolsky, Vladislav Volkov and Viktor Patsayev – were killed in 1971 when their capsule depressurised abruptly as they prepared to re-enter the atmosphere. They are the only deaths of humans to have occurred in space: all other spaceflight fatalities having happened inside Earth’s atmosphere.

Since then, Soyuz has earned itself a reputation for safety and reliability though its descent to Earth, said Sharman, remains a dramatic experience. “The G-force is five times normal gravity. You can see the part of the spaceship outer shell which starts to glow as it heats up as it plunges into the atmosphere and bits start to burn off. Then when the parachute opens you get jerked from side to side. It’s a lumpy and bumpy ride.”

For all its discomforts, this is the form of manned spacecraft that has prevailed over the decades. In the 90s, China took the model of Soyuz and used it to make their near-identical Shenzhou spacecraft. Then, after suffering two calamitous losses, the US abandoned its space shuttle – although it was a far more sophisticated craft that was capable of gliding to a stress-free landing like an airliner.

Abandoning the shuttle left Soyuz as the only means to get to and from the International Space Station – though some upgrades have been made over the years. “For one thing, its interior had to be changed to make room for American astronauts – who tend to be bigger than Russian cosmonauts and who were having trouble fitting in on flights to the space station,” said Millard.

The fact that the world now relies on one single capsule, developed in the 1960s, to ferry astronauts into space is striking. For some it suggests that manned spaceflight no longer commands its former interest. “Manned space flight in the US has gone the same way as supersonic airliners, like Concorde,” said the astronomer royal, Martin Rees. “They are both examples of technology that were developed but have been dropped because it was found they were not needed.”

American entrepreneurs are now developing space capsules such as Boeing’s Starliner and SpaceX’s Dragon 2 – though it remains to see how successful they will be. By contrast, robot probes are becoming more sophisticated, said Rees. “It is robots, and not humans, that will explore the planets,” he added. “And the cost gap between manned and unmanned missions remains huge, so the practical need for manned space flight gets ever weaker with each advance made in robots and miniaturisation.”

How Soyuz will fare in such a future, it is hard to predict. It is incredibly reliable and quite sufficient for current needs to supply the International Space Station. New US spacecraft may undercut the Soyuz costs but as yet none has flown. For his part, Baker is confident of the spacecraft’s short-term future: “My money is on Soyuz’s still being with us for a while yet.”

HAPPY BIRTHDAY, COMRADE

A Soyuz spacecraft is made up of three separate sections:

■ A spheroid orbital module, which provides accommodation for a crew of up to three.

■ A small aerodynamic descent module in which the cosmonauts return to Earth.

■ A cylindrical service module onto which the craft’s solar panels are attached, and which contains instruments and rocket engines.

The orbital and service modules are jettisoned when Soyuz re-enters the atmosphere. The descent module drifts by parachute to the ground. A few metres before it touches down, a small rocket is fired to cushion the landing impact.

The Soviets also developed the Soyuz rocket, also still in use today, either to launch Soyuz capsules or other unmanned space vehicles. The European Space Agency probe Venus Express was launched on a Soyuz rocket, for example. It is the world’s most reliable space launcher.