Preparations and testing in advance of the Planetary Society's orbital solar sail mission called Cosmos 1 are making progress in Russia, officials report.

The first-ever solar sail is scheduled for launch no earlier than September aboard a Russian submarine-launched Volna rocket.

Cosmos 1's recent milestones have included the engineering model's completion of launch vibration tests that simulate the environment the spacecraft will endure during the launch and other critical phases of the flight.

Officials say that the craft came out of testing in a good posture to support a September launch date. The team will soon integrate all the flight components of Cosmos 1.

Another milestone was the arrival of the "kick motor" that will provide the final nudge to push Cosmos 1 into orbit. The Volna rocket itself will only place the satellite into a ballistic trajectory.

Most of the scientific, communications, and electrical parts of the spacecraft have been delivered, Project Director Louis Friedman reported in an online status report. The only notable exceptions are the camera that will be placed aboard Cosmos 1 to observe the deployment of the eight solar sail blades, the S-band radio, and the main computer. "Our biggest concern is the delivery of the on-board computer with complete software," Friedman wrote.

The launch of the Cosmos 1 solar sail has suffered repeated delays that combine to total almost a year. "We have had delays and have accepted those delays in order to develop the spacecraft as reliably as possible," Friedman said.

A thorough status review is expected before the end of May, and only then will the Cosmos team request a launch date from the Russian Navy, who will conduct the launch.

The Cosmos mission encountered a setback last July when a suborbital two-blade test flight failed because the spacecraft did not separate from the Volna rocket's upper stage. It is believed that the stage did not develop sufficient thrust, causing computers to order the craft to not separate.

Once in orbit, Cosmos 1 will deploy eight solar sail blades that are supposed to use light energy from the Sun for propulsion. Ground controllers will analyze orbital data to see if the orbit is raised by even a small amount by the Sun's rays.

The 88-pound spacecraft will also carry a camera that will capture pictures of the solar sails during the mission.