 The crew, however, had discarded the service module with the malfunctioning engine and the final component of the Spektar-15, an optoelectronic block, before descent.This meant that the malfunction could not be examined and a new Spektar optoelectronic block had to be produced for future missions.It was later integrated with the rest of the equipment on Salyut 6 and the Bulgarian experiments were initiated in 1981 by Soviet cosmonauts.