A classified military satellite for the Russian Ministry of Defense will ride into orbit this month atop a Ukrainian-built Zenit 2 rocket, currently being readied for launch on September 25th from the Baikonur Cosmodrome.

Sources within the industry said that the spacecraft, code-named Enisei, is the Zenit's primary payload. The Enisei spacecraft, named after a Siberian river, is not part of any known Russian project. However, Russian sources said that the satellite could be a likely successor to the Orlets 2 reconnaissance spacecraft, previously launched by a Zenit 2.

Orlets 2, one of the most advanced Russian spy satellites, provides high-resolution intelligence imagery. The 12-ton spacecraft sports 22 reentry capsules that are used to return exposed photographic film to Earth. Orlets satellites are built by the TsSKB development center in the Russian city of Samara. The last spacecraft of this type was launched in 1994.

Earlier reports indicated that the payload for the upcoming Zenit launch would be a Tselina 2 electronic-intelligence spacecraft. Tselina 2 has been the most frequent military payload carried by the Zenit 2, including the most recent launch last February.

On Wednesday, Yuri Alexeenko, the representative of Yuzhnoe Design Center in Dnepropetrovsk, Ukraine said that a Russian manufacturer supplied the payload for the upcoming flight and Yuzhnoe provided only the launch vehicle for this mission. Yuzhnoe is a manufacturer of both Zenit rockets and Tselina satellites.

According to Alekseenko, the Zenit 2 and its payload have already been delivered to Baikonur and the processing team from Yuzhnoe arrived at the Kazakhstan launch site to assist in preparation for the launch.

Sea Launch is a joint venture between Ukrainian, Russian, Norwegian and U.S. companies. The Yuzhnoe representatives said that the next Sea Launch mission would take place in October. It will carry a Thuraya communications satellite for the United Arab Emirates. The launch was previously slated for the end of September.