MOSCOW (AP) -- The head of Russia's space agency said Tuesday that cosmic radiation was the most likely cause of the failure of a Mars moon probe that crashed to Earth this month, and suggested that a low-quality imported component may have been vulnerable to the radiation.
The unmanned probe was to have gone to the Mars moon of Phobos, taken soil samples and brought them back. But it became stuck in Earth orbit soon after its launch on Nov. 9. It fell out of orbit on Jan. 15, reportedly off the coast of Chile, but no fragments have been found.
The failure was a severe embarrassment to Russia, and space agency head Vladimir Popovkin initially suggested it could have been due to foreign sabotage.
But Russian news agencies on Tuesday quoted him as saying an investigation showed the probable cause was "localized influence of heavily radiated space particles."
Popovkin, speaking in the city of Voronezh where the report was presented to Deputy Prime Minister Dmitry Rogozin, said two units of the Phobos-Ground probe's onboard computer system went into an energy-saving "restart" mode, apparently due to the radiation, while the craft was in its second orbital circuit.
It was not immediately clear why the units could not be brought out of that mode.
Popovkin was quoted as saying that some microchips used on the craft were imported and possibly of inadequate quality to resist radiation. He did not specify where the chips were manufactured.
Popovkin also said the craft's builder, Moscow-based NPO Lavochkin, should have taken into account the possibility of radiation interfering with the operation and said Lavochkin officials would face punishment for the oversight.
Russia's space program has suffered a series of notable failures in recent months, including the August crash of an unmanned ship that was to send supplies to the International Space Station. That crash forced the postponement of a manned launch to the ISS because the booster rocket that failed in the crash was similar to the ones used in manned missions.
On Tuesday, Russian news agencies reported that a manned launch to the ISS that had been scheduled for March 30 will be postponed for about 45 days because tests of the capsule showed flaws in its hermetic seals.