Russian Mars probe Phobos-Grunt was lost because space radiation disrupted its computer system, a commission investigating the incident said on Friday. The investigation found no faults with the spacecraft's hardware, the commission said in a summary of its report, released on the website of the Federal Space Agency.

Phobos-Grunt, Russia's first interplanetary probe in years, was to travel to Phobos, a moon of Mars, and bring back samples of its soil by 2014. The $165 million spacecraft was launched in November, but got stuck in low Earth orbit.

Attempts to restore contact with Phobos-Grunt failed, and in January, the 13-ton probe crashed into the Pacific Ocean west of Chile.

The commission to investigate the incident, created by the Federal Space Agency, studied more than 700 documents related to Phobos-Grunt's construction, as well as data from its short-lived flight.

All units of the spacecraft withstood rigorous testing on Earth and functioned properly during the launch, the commission said in its report.

But heavy ion bombardment corrupted program code in two components of the probe's computer, which resulted in the loss of the probe, the commission said. The version of the incident was reported earlier this week by Kommersant daily, but not confirmed officially at the time.

The commission did not elaborate on why the developers took no measures to protect Phobos-Grunt against such incidents.

Yury Koptev, who heads the investigation into the incident, speculated last month that Phobos-Grunt's computer could have been disrupted by a U.S. radar on Marshall Islands, but that version was eventually discarded.

Russia has lost five satellites and a space truck in failed launches since December 2010. The first failures cost Federal Space Agency head Anatoly Perminov his job last April, but his replacement, Vladimir Popovkin, failed to break the spell.

Developers should have installed several backup systems to counter malfunctions such as one that brought Phobos-Grunt down, Nikolai Vedenkin, a researcher at the Moscow State University who supervised the university's own space program, said by telephone on Friday.

"Either the whole system was configured wrong, or it's simply not true," Vedenkin said about the commission's version of the reasons for Phobos-Grunt's crash.

He said the probe was likely lost because of confusion during its development and testing, which was rushed and saw the head constructor changed mid-project.

"The mistakes snowballed, and the probe was launched when still not ready," Vedenkin said.