PASADENA, Calif. — Organizers of a bold attempt to fly the world's first solar sail spacecraft all but conceded Wednesday that their Cosmos 1 never reached orbit this week because of a failure of its Russian booster rocket, but said they were undeterred from the risky business of space exploration.

Russia's space agency said with "some definitiveness" that the rocket's first stage failed and did not put Cosmos 1 in orbit, but tracking stations continued to search because of a slim possibility that it did get into orbit, project director Louis D. Friedman said in a telephone briefing from Moscow to The Planetary Society headquarters.

"We all rate it as a 1 percent probability of something like that, but stranger things have happened," said Friedman, a veteran of military and civilian space programs including NASA's Mariner, Voyager and Magellan.

Cosmos 1 was launched Tuesday atop a converted intercontinental ballistic missile fired from a Russian submarine under the Barents Sea. After four days in orbit it was supposed to unfurl eight, 50-foot-long Mylar sails that would be propelled by the subtle pressure of sunlight and make controlled orbits of Earth.

The Planetary Society mission team and its backers, who hoped for a revolutionary demonstration of a technology envisioned for interstellar flight, said they were not deterred.

"We have no regrets over what happened," said Bruce Murray, a former director of NASA's Jet Propulsion Laboratory who founded The Planetary Society with the late astronomer Carl Sagan and Friedman. "We've learned a lot and I think we've shown what can be possible and what might be able to be done."

Sagan's widow, Ann Druyan, whose Cosmos Studio was the principal backer of the $4 million project, said that in conversations with those who helped her finance the mission the words "Cosmos 2" were used repeatedly.

"This may be the down part of the story rather than the triumph we'd hoped for, but I really don't think the story is over," she said. "No matter what the fate of Cosmos 1, I really do think that all of us involved in this mission are going to stay in the exploration business."

According to Russian officials, the booster rocket's first stage failed 83 seconds into the flight.

But tracking stations on Russia's Kamchatka peninsula, in the South Pacific and in the Czech Republic recorded signals that seemed to be transmissions from Cosmos 1, Planetary Society officials said, leaving the possibility that the craft made it part way around the globe or actually was in orbit, waiting to be found.

The apparent transmissions coincided with times when the spacecraft's transmitter would have been turned on and with roughly the expected frequency, officials said.

"This is inconsistent with the analysis that the people in charge of the launch vehicle have put in and that inconsistency, frankly, can't be explained," Friedman said. "And since the launch vehicle people are definite about it we have no reason to say that we can disagree with them. All we can do is investigate further."

Noting that Cosmos 1 was an international mission and the European Space Agency is scheduled to use the same launch system in two weeks, Friedman said he was confident of an open investigation and that "we'll find out how it really happened."

But he indicated there were limits on what might be revealed.

Asked for specifics on the firing times of the booster stages, Friedman said he did not know the answer and added, "I feel it's not our place, certainly not my place, to try to give details on this part of the mission."

"This is a navy launch. It's pretty sensitive," he said. "It's an ICBM. It's part of the Russian ICBM fleet and in fact there's even a law in the United States that says the U.S. cannot participate in the investigation of such accidents."

He also said the matter was covered by the Strategic Arms Reduction Treaty.

"So we have no business getting into this," he said. "So I'm actually going to say that all such questions should be directed to the Russian space agency or the Russian navy, and good luck at that."

Friedman noted a slim possibility for spotting Cosmos 1 if it did enter orbit and was working: On Saturday its autonomous program would deploy the reflective solar sails, which someone might be able to see.

Source: Associated Press