Russia’s workhorse Proton rocket has likely delivered a telecommunication satellite into a wrong orbit in only its second launch after a five-month hiatus following a launch failure in May.
The Proton rocket, which has a backlog of about 400 successful launches since 1965, lifted off from Russia’s main cosmodrome in Baikonour, Kazakhstan, on Tuesday 15:09GMT. Despite the original reports that the launch was a success with all rocket stages firing as scheduled, it was later suggested that the rocket’s payload, the Ekspress-AM6 communications satellite, ended up in a slightly incorrect orbit.
Russian officials didn’t confirm the speculations.
According to Russian Spaceweb, the Briz M upper stage responsible for the delivery of the satellite into the geostationary transfer orbit, an elliptical orbit with an apogee some 36,000km above the Earth, may have shut down earlier than required during some of its four ignitions.
The available data suggests the final fourth firing ended 24 seconds early or 50 meters per second short of required velocity. As a result, the satellite may now be in an elliptical orbit with the lowest point 2,500 kilometers lower than expected.
It is likely that satellite controllers will be able to make up for that deficit using some of the on-board fuel. However, such extensive manoeuvres would probably decrease the satellite’s life expectancy.
The Ekspress-AM6, designed and built by ISS-Reshetnev for the Russian Satellite Communications Company, is supposed to provide digital television and radio broadcasting services across Russia as well as voice and data transmission for mobile telephony, Internet access or video-conferencing.
The satellite, with a 15-year scheduled life time, is one of the most advanced telecommunication satellites ever built in Russia.
In May this year, the Russian Satellite Communications Company lost the Ekspress-AM4R satellite built by Astrium as a replacement for another spacecraft lost in 2012 due to a faulty Briz M upper stage – the same as likely responsible for this week’s glitch.
The Ekspress-AM4R satellite in May this year was destroyed after the third stage of the Proton-M launcher malfunctioned, resulting in the spacecraft burning up in the atmosphere only nine minutes after lift-off.
An ensuing investigation identified the probable cause of the failure to be the loss of structural integrity of a bolted interface that attaches the Stage III steering engine turbopump to the main engine structural frame.
The resulting vibrations of the turbopump damaged a fuel inlet of the oxidizer gas generator leading to a fuel leak and a subsequent shut down of the turbopump and loss of stage control.
Russia's space agency Roscosmos only resumed Proton launches in September. The vehicle is a frequent choice of telecoms companies from around the world to deliver their satellites to orbit, all of which have been heavily delayed due to the five-month investigation.