MOSCOW, May 19. /TASS/. A failure to correct the orbit of the International Space Station (ISS) on May 16 was due to a software error and was unrelated to the Progress M-26M space freighter’s engines, a source in the rocket and space industry said on Tuesday.
"Everything is well with the Progress spaceship’s engines and there are no breakdowns. The problem is with mathematics, i.e. with software. But specialists continue finding out the root cause for the failed attempt. So far, it is unclear," the source said.
Preparations for the ISS orbit correction proceeded in a normal mode on May 16 and Mission Control issued and registered a command sent to the Progress freighter’s central computer to switch in the spaceship’s main panel, through which its eight engines are controlled, he said.
However, Mission Control failed to receive a response signal from the space freighter, which is regarded as an emergency situation. It was the software that blocked the maneuver, he said.
"On May 18, the ISS orbit was corrected with the help of a back-up operation panel providing for the work of only four engines. The maneuver was made in a normal mode," he said.
The source said he was confident the off-nominal situation would not affect an operation for the space freighter to undock from the ISS and quit the orbit.
"There are no causes for any worry. The spaceship’s propulsion system is working," he said.
The correction of the ISS orbit was successfully carried out overnight to May 18. The space station’s orbit was raised by 2.8 km (1.7 miles) to create optimal conditions for the ISS crew landing on June 11 and the launch of a new space freighter to the space station scheduled for July 3, according to available data.