The first series, SSBS S1, was launched between 1965 and 1968. It had a maximum altitude of 500 kilometres (310 mi), a lift off thrust of 440 kN, total mass of 25,000 kilograms (55,000 lb), a diameter of 1.50 metres (59 in) and a total length of 15.10 metres (49.5 ft).[1]