payload shroud jettison. However, third stage ignition did not occur on time and reports filtered back to the launch center that the booster had exploded. Investigation found that an imbalanced rotor in the third stage oxidizer turbopump had started a fire, which led to loss of thrust and vehicle breakup. The remains of the third stage and probe impacted in the Altai Mountains. Even more difficult for Soviet engineers was the news that Mariner 7 had been successfully launched from Cape Canaveral a few days earlier, and their next Mars launch also failed a few days later. Scientific Instruments The scientific instruments were: Radiometer Instrument to measure water vapor levels Ultraviolet spectrometer Gamma spectrometer Hydrogen mass spectrometer Helium mass spectrometer Spectrometer Low energy ion spectrometer Imaging System (With three on board cameras) See also List of missions to Mars References External links Cornell University's Mars Missions page The Soviet Mars program, Professor Chris Mihos, Case Western Reserve University Spacecraft launched in 1969 1969 in the Soviet Union Mars program