Phobos One: A Command That Changed Course

Transcript

Phobos One was part of the Soviet effort to study Mars and its moon Phobos. Its planned route depended on reaching orbit around Mars. Then, on 29 August 1988, a programming error sent the spacecraft a command to switch off its orientation and stabilization system. The command should instead have activated a gamma-ray spectrometer. Without its normal stabilization, Phobos One lost its proper orientation toward the Sun. Its solar panels turned away from sunlight, and the spacecraft’s power began to fall. At the next scheduled communications session, on 2 September, there was no response. Contact attempts continued, but ended on 3 November. Phobos One passed Mars without entering orbit, so its central Mars-orbit objective was lost. Yet the mission was not without results. Its Terek solar telescope returned significant data about the Sun’s chromosphere, corona, and transition layer, regions that had been little studied. Phobos One missed its planned encounter with Mars as an orbiter, but still produced valuable observations of the Sun.