January 17

A plausible scenario for quick demise of Phobos-Grunt leaked from industry sources to the online forum of the Novosti Kosmonavtiki magazine on January 17.

The most likely culprit in the failure of the probe's propulsion unit to ignite soon after it had entered orbit on November 9 was a programming error in the flight control system. Post-failure tests (apparently simulating in-flight conditions) revealed that in 90 percent of cases, the processor of the main flight control computer onboard the spacecraft would be overloaded. It could easily lead to crashes and rebooting as more systems were being activated after the spacecraft had left the range of Russian ground control stations after reaching orbit. Among those systems were star trackers (used for attitude control in the shadow of the Earth) and a Chinese satellite. In the meantime, the power supply system onboard the spacecraft worked flawlessly.

Following the initial failure, as ground controllers apparently succeeded in activating the X-band transmitter onboard the spacecraft, new problems arose. The device would transmit a signal with a power of around 40 watts, however its own operation would consume around 200 watts. The deactivation of the transmitter was not taking place when the spacecraft was flying in the shadow of the Earth for prolonged periods of time. As a result, the probe slowly drained its recharable power batteries and then its emergency power source KhIT, leading to a complete deactivation of onboard systems on November 28, 2011.