The Mars 4 automatic station was intended to be a Mars orbiter mission. The orbiter had a fully fueled launch mass of 3440 kg. Launched to Mars by a Proton SL-12/D-1-e booster, it reached Mars on 10 February 1974. Due to a flaw in the computer chip which resulted in degradation of the chip during the voyage to Mars, the retro-rockets never fired to slow the craft into Mars orbit, and Mars 4 flew by the planet at a range of 2200 km. It returned one swath of pictures and some radio occultation data. The spacecraft was also equipped with a Lyman-Alpha photometer.