MOSCOW, May 18. /TASS/. The state commission investigating the accident with Russia’s Soyuz-2.1a carrier rocket and the Progress space freighter considers several versions of the rocket’s fuel tank depressurization, including high flight loads and a production defect, a commission member said on Monday.
"It is not yet finally clear to us what specifically happened. Based on available telemetry, the physics of explosive processes and the experience of specialists involved in the commission’s work, several most probable causes for the accident were outlined," the source said.
"Two of them involve enhanced loads on the third stage and disruption in the technology of the fuel tanks’ production," he said.
"It has been clearly established that the third stage’s engines had nothing to do with the emergency situation with the Soyuz-2.1a rocket," the source said.
The commission’s members are currently studying parts and systems of the rocket’s third stage at enterprises of the rocket and space industry, checking them on stands and modelling the emergency situation," he said.
The Soyuz-2.1a carrier rocket with the Progress space freighter blasted off from the Baikonur space center in Kazakhstan on April 28. However, the carrier rocket failed to put the cargo ship into a designated orbit and Russia’s Mission Control lost communications with the space freighter that was intended to deliver supplies to the International Space Station.
The Progress cargo ship burnt up in the dense layers of the Earth’s atmosphere over the Pacific Ocean in the morning of May 8.
Roscosmos later said the accident had been caused by the "off-nominal separation of the third stage of the Soyuz and Progress space vehicles" as a result of the fuel tanks’ depressurization.
The causes for the Progress space freighter accident are currently being investigated. The results of the investigation are expected to be announced before May 22.
Roscosmos First Deputy Head Alexander Ivanov earlier said preparations for the launch of a military satellite from the Plesetsk space center had been suspended until May 22 over the Progress space freighter accident.