 In December 1978, Spektar-15, a Bulgarian-made spectrometric system, was installed on the Salyut 6 training mock-up at Yuri Gagarin Cosmonaut Training Center.It was subsequently approved for space use.Elements of the Spektar-15 were delivered to Salyut 6 on 14 March 1979 with the Progress 5 flight; these included the data storage block, the eyepiece, lens and filters.