PARIS — Russia’s long-delayed Spektr-R astronomy satellite is in final preparations for a late-July launch aboard a Zenit rocket with a Fregat-SB upper stage, the Russian space agency, Roscosmos, said June 16.

In a statement, Roscosmos said assembly of the Fregat stage at Russia’s Baikonur Cosmodrome spaceport in Kazakhstan is proceeding quickly enough to maintain the July launch date.

Featuring a 10-meter-diameter antenna, Spektr-R is part of the international RadioAstron astronomy project. The satellite was originally scheduled for launch in 2004 or 2005 before encountering multiple delays in its construction.

More recently, the launch date was put into question as satellite fleet operator Intelsat of Washington and Luxembourg sought to secure Zenit rocket hardware to launch the Intelsat-18 satellite, also from Baikonur.

Intelsat recently concluded an agreement with Sea Launch Co. of Long Beach, Calif., to use a Zenit rocket that Sea Launch had available to it.