before ground crews could locate it. The next landing window was now 2–15 October, suggesting the anticipated Cuban launch would be 24 September, but observers were caught off guard once again when Soyuz 38 was launched 18 September, almost a week earlier than anticipated. Cuban Arnaldo Tamayo Méndez, the first space-farer of African descent, was accompanied by Yuri Romanenko into space, the fourth crew to visit the resident crew. The early launch date was intended to allow Cubans to be able to see their countryman overhead. Twenty-seven material processing and medical experiments were carried out by the visiting crew. As the Soyuz 35 crew were returning to Earth soon, the Soyuz 38 crew didn't swap their craft when they returned on 26 September. The launch, therefore, of Progress 11 on 28 September came as surprise to observers, as it was assumed cosmonauts due to return to Earth would not need fresh supplies. Indeed, by the time the Soyuz 35 crew returned on 11 October, the Progress was only partially unloaded. In fact the real purpose of Progress 11 was to boost Salyut 6 into a higher orbit during the six months between crew residencies, since its defective propulsion system could no longer be used. The crew set a new space endurance mark of 185 days, but the record was not recognized by the IAF as it had not exceeded the previous 175-day record by the required minimum of 10 per cent. Ryumin had become by far the most experienced space-farer to that date, with a total of 352 days spent in space over three missions. Unusually, the crew had gained an average of 2 kg during the flight. This was explained by the crew's strict adherence to exercises and diet. By the day after landing, they were able to walk for half an hour. By 15 October, they were playing tennis. Thousands of Earth resources photographs were taken, as were more than 40,000 spectrograms. The fourth Salyut 6 residency was at last a complete success after the numerous technical malfunctions that dogged the first three crews. References Crewed Soyuz missions 1980 in the Soviet Union Spacecraft launched in 1980 Spacecraft which reentered in 1980 Spacecraft launched by Soyuz-U rockets