Cosmic radiation and a low-quality imported component that was vulnerable to the radiation, were the most likely causes of the failure of Russia's Mars moon probe that crashed to Earth this month, according to Vladimir Popovkin, head of Russia's space agency.

However, an industry source leaked more critical details from the investigation into the Phobos-Grunt failure.

According to the report, sub-commission No. 2, which looked into the behavior of the probe's flight control system, concluded that the loss of the mission failure was the result of the design error and the lack in the ground testing of BKU.

The shortcomings of the BKU system, which was essentially the brain of the spacecraft, had been well documented even before the doomed launch. The findings of sub-commission No. 2 could be the most critical part of the investigation as it formulates the most probably cause of the failure.

Officials of NPO Lavochkin, Phobos-Grunt probe's prime developer, on the other hand, may face punishment for their oversight in using microchips in the probe that were "industrial" class, a less-sophisticated level than should be used in space flight, according Popovkin.

He said the NPO Lavochkin should have taken into account the possibility of radiation interfering with the operation of the Phobos-Grunt probe.

Popovkin had initially suggested the failure of the Phobos-Grunt probe could have been due to foreign sabotage. However, early this week he said in televised statement that an investigation showed the probable cause was "localized influence of heavily radiated space particles."

According to Popovkin, two units of the Phobos-Ground probe's onboard computer system went into an energy-saving "restart" mode while the craft was in its second orbital circuit, adding that some imported microchips used on the craft were possibly of inadequate quality to resist radiation.

The unmanned Phobos-Ground probe aimed to bring soil samples from Mars moon Phobos. However, it became stuck in Earth orbit soon after its launch on Nov. 9 and falling out of orbit on Jan. 15.