The Mars 7 interplanetary station was intended to be a Mars lander. It consisted of an orbital bus and lander with a total fueled launch mass of 3260 kg. It was launched by a Proton SL-12/D-1-e booster and reached Mars on 9 March 1974. Due to a problem in the operation of one of the onboard systems (attitude control or retro-rockets) the landing probe separated prematurely and missed the planet by 1300 km. The early separation was probably due to a computer chip error which resulted in degradation of the systems during the trip to Mars. The lander instrumentation for the experiments included a Lyman-Alpha photometer.