The scientific payload aboard Russia's solar research satellite Koronas-Foton was switched off owing to power supply problems on 1 December, Novosti news agency reported. Contact with the spacecraft was subsequently lost, and all attempts to revive the spacecraft failed.

In its orbit, the satellite can monitor the Sun for as long as 25 consecutive days, after which period it will however enter Earth's shadow for a certain amount of time.

The problem started in July 2009 during such an eclipse period when the two onboard batteries failed to provide sufficient power. Switching to a backup battery did not improve the situation. As a consequence, the science payload as well as the satellite's heaters shut down about once a month. The intermittent power supply also led to the failure of a sub-unit in the spacecraft's flight control system and the activation of a backup unit.

The flight control system on 1 December then completely turned off one of the batteries because it had become inoperable. The scientific payload was turned off, and reportedly the remaining battery sustained basic operations for about one day, after which ground control lost contact with the satellite.

Yuriy Zaytsev, academic adviser at the Russian Academy of Engineering Sciences, said that "there were hopes that after the satellite reached shadow-free orbit, where solar panels would be continuously illuminated by the Sun, the batteries could be recharged and scientific instruments would be re-activated. However, these hopes were dashed."

He noted that the designer of the satellite - the All-Russia Research and Development Institute of Electromechanics (VNIIEM) - had given a guarantee that it would remain active for three years. In reality, the satellite functioned for no more than 11 months.

"The official reason for the incident is that the designers underestimated how much power would be consumed by the equipment on board the satellite, so its batteries' capacity was insufficient," Mr. Zaytsev said.

Last updated: 23 January 2010