damaged by the main engine, potentially leaving the crew stranded with five days of supplies while it would take ten days for the orbit to decay. The station could have been moved to within 1,000 m of the craft, but the two craft were drifting apart at 28 metres per second, and time was needed to calculate the manoeuvres. In any event, four crew on the station with one malfunctioning Soyuz and a second Soyuz (Soyuz 32) with a now-questionable engine (it had the same type as Soyuz 33) was not considered the best option. In the end, the backup engine did fire, though for 25 seconds too long, resulting in an unusually steep trajectory and loads of 10 Gs to be endured by the crew. Rukavishnikov and Ivanov were safely recovered. Progress 6, uncrewed Soyuz launched The failure of a prestigious international mission was an embarrassment to Soviet authorities and also had a negative effect on the morale of Ryumin and Lyhakov, both of whom had been looking forward to receiving visitors. News of the cancellation of the Soyuz 33 flight was greeted by a series of grunts followed by the termination of all voice communication by the Salyut 6 crew. Their bad mood persisted for several days. After the Soyuz 33 failure, the station crew were stuck with a suspect craft. The Soyuz 33 craft was intended to be swapped for the Soyuz 32, but the failure called into question the reliability of Soyuz 32's main engine. Until the design was corrected and a new vehicle launched, the crew was safe on Salyut with the Soyuz usable in an emergency. The fifth international flight, scheduled for 5 June, was postponed. Lyakhov and Ryumin continued their station activities, including experiments intended to be carried out with the visiting crew (which had been delivered aboard the Progress 5 flight), such as one called Pirin which investigated the formation of metal whiskers on zinc crystals, and another which made multi-spectral measurements of the daylight atmosphere. They were given five days off for the May Day holiday. Progress 6 was launched 13 May and delivered some 100 items. The Soyuz 33 engine failure did not affect the supply tanker as it differed in its design. Unloading took two days, a new navigational unit was installed, and the tanker raised the station's orbit on 22 May. Refueling was completed by 28 May, more