Posted: Sun, Jul 22, 2001, 7:05 PM ET (2305 GMT)

A problem with the computer in the upper stage of a Russian missile is considered the likely cause of the failure of a suborbital test flight of a solar sail Thursday night, the Planetary Society reported Saturday. A preliminary review of the telemetry from the Volna booster found that the command to separate the Cosmos 1 spacecraft from the upper stage of the booster was countermanded by the booster's computers because "dynamic variations" were recorded in the stage. Because the separation command was not executed, the Cosmos 1 spacecraft remained attached to the upper stage and its reentry shield did not deploy. Project officials believe the spacecraft and attached upper stage reentered over the Kamchatka Peninsula of the Russian Far East; efforts continue to recover any debris from the spacecraft and booster. The flight was intended to test the technique for deploying the blades of the Cosmos 1 solar sail spacecraft that the Planetary Society planned to place in orbit later this year. Planetary Society president Bruce Murray said he was optimistic that the Society would still be able to launch Cosmos 1 this year.