First an explosion postponed the test of the Cosmos 1 solar sail. Then the rescheduled flight was delayed by the salvage effort for the ill-fated Kursk submarine in the Barents Sea. Finally, on July 20, the craft, developed for The Planetary Society of Pasadena, Calif., made a picture-perfect suborbital flight, launched atop a Volna rocket from the submarine Borisoglebsk.

Or so it seemed. Researchers knew something was wrong when they could not locate the re-entry capsule containing the flight recorder that monitored the performance of the sail. They initially suspected a malfunctioning beacon but now believe that the solar sail and re-entry capsule never separated from the rocket's upper stage. All are suspected to have crashed somewhere on the Kamchatka peninsula.

Following the test, Louis Friedman, executive director of The Planetary Society, said in a statement that the orbital flight of the 600-m² aluminized Mylar sail remains on schedule for this fall.