A group of Russian engineers has made its final report on last month's failure of a privately funded mission to test the world's first solar sail in space. The group financing the flight responded sharply with criticism toward project and launch vehicle teams.

With over four years of work behind them, officials in the United States and Russia stood on the sidelines on June 21 as they put their spacecraft in the hands of the Russian Navy responsible for launching the sail aboard a Volna rocket.

The converted ballistic missile, formerly of Russia's nuclear arsenal, shot out of its launch tube from a Russian Navy submarine hovering beneath the Barents Sea off the country's northern coast. Plans then called for the rocket to leave the Cosmos 1 solar sail and a kick motor in a suborbital trajectory before the injection module fired to deploy the spacecraft in its target orbit some 800 kilometers high.

As the craft's Russian manufacturers attempted to gain contact in the minutes and hours after launch, it soon became clear something went awry during the rocket's firing.

The Planetary Society -- financier of the Cosmos 1 project -- reported online Wednesday that the Volna Failure Review Board has completed its investigation into the botched launch. Initially convened by the Makeev Rocket Design Bureau, the group made its final report to the Russian space agency Roskosmos.

The probe revealed there was enough telemetry data to determine that the Volna's first stage engine did not complete is planned 100-second burn before jettisoning from the rest of the vehicle. Instead, the engine -- powered by nitrogen tetroxide and unsymmetrical dimethyl hydrazine -- shut down 82.86 seconds into flight, and the planned separation of the first and second stages did not occur. Officials deemed the engine problems were caused by a "critical degradation in operations capability of the engine turbopump."

Therefore, the craft never stood a chance to achieve orbit, and the booster's control system aborted the launch about 160 seconds after first stage ignition. "They did not describe any telemetry data to support the conclusion that the rocket's stages never separated," Cosmos 1 project manager and Planetary Society executive director Louis Friedman said in a statement.

Under this scenario, the payload and rocket likely fell into the Barents Sea a few hundred kilometers east of the launch area near the city of Murmansk.

The board was composed of representatives from Makeev, which built the Volna rocket in question, Cosmos 1 manufacturer NPO Lavochkin, and engineers from a Roskosmos center.

"No one involved with spacecraft tracking or on-board electronics participated in the analysis, and the board did not review or consider the data received at the Kamchatka portable tracking station that some of the team think might have come from the spacecraft," Friedman said.

Planetary Society officials have long contended that Doppler tracking signals received at a portable ground station at Petropavlovsk on the Kamchatka peninsula in eastern Russia could have come from Cosmos 1 as it flew overhead. Later communications passes in the Marshall Islands and the Czech Republic produced less distinct data, which U.S. engineers have now discounted.

"That would only have been possible if the spacecraft had separated from the rocket and its orbit insertion motor had fired."

"It appears almost certain that we have received signals from the spacecraft after it was injected into orbit," Dr. Viacheslav Linkin, Cosmos 1's science manager from Russia's Space Research Institute, said earlier this month.

The Planetary Society said they were not invited to be part of the failure investigation, and international arms traffic regulations require an approval before organizations can take part in accident probes involving defense weapons and services.

"Even before the failure review, there was a serious lack of communication and coordination with the project and launch vehicle teams," Friedman noted.

"What's so excruciatingly frustrating is that we were done in by a launch vehicle failure. Our spacecraft never got a chance even to try," Friedman said a few days after the launch. "But we chose to launch on the Volna, and we take responsibility for that."

The Planetary Society is currently plotting their next course of action in the Cosmos 1 project, and officials say the story of Cosmos 1 is not over. "The Society is considering its next steps in planning how we will try again. We need additional data before we can reach an independent conclusion about whether or not the Volna's stages separated and the spacecraft's orbit insertion motor fired. With that information, we will be better able to chart our course for the next flight of a solar sail."