Russia's space agency says its specialists are attempting to fix problems that have blocked control of an orbiting radio telescope.

The Spektr-R is continuing to transmit signals, but scientists have been unable to control the satellite since Friday.

The satellite was launched in 2011 and has exceeded its initially expected useful life of about three years. It is used to study radio sources within and outside Earth's galaxy.

An official from Russian space agency Roscosmos, Alexander Bloshenko, said Saturday that another attempt to establish control of the satellite will take place Sunday.