Spektr-R: Russia's only space telescope 'not responding'
Russia's only space radio telescope is no longer responding to commands from Earth, officials say.
Astro Space Centre chief Nikolai Kardashev said some of the Spektr-R satellite's communication systems had stopped working.
But it was still transmitting scientific data, RIA Novosti news agency reports.
The telescope has been operational way beyond its expected five-year lifespan, Russia's space agency Roskosmos says.
Specialists had repeatedly tried and failed to fix the lost connection, Mr Kardashev said.
Yuri Kovalev, head of research for the Spektr-R project, said the link went down on the morning of 11 January, but added that "there is still hope".
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Spektr-R was launched into space in 2011.
A new Russian-German satellite, Spektr-RG, is scheduled to be launched this year.