A Russian satellite to study dark energy forces by observing galaxies has been delayed due to problems with a German-built telescope, a science official said.

The satellite, designed to observe cosmic X-rays in an attempt to unlock the secrets of so-called dark energy -- a force believed to be accelerating the expansion of the universe, -- was to have been launched next year but now will be delayed until 2015, Mikhail Pavlinsky, head of high-energy astrophysics at the Russian Academy of Sciences, said.

The Spektr-RG satellite is named after the Roentgen (X-ray) and Gamma radiation it will observe.

A sensor on one of the satellites two telescopes was malfunctioning and attempts to fix it have shown its circuitry must be completely redesigned, RIA Novosti reported Thursday.

Its manufacturer, the Max Planck Institute for Extraterrestrial Physics near Munich, will do the reconstruction of the malfunctioning unit, officials said.

The craft's other main telescope, built in Russia, has not experienced any significant problems, they said.

A third wide-field X-ray observation instrument for the satellite is to be provided by Britain's Leicester University.