CAPE CANAVERAL -- When a Russian satellite broke apart in February, it spewed at least 50 pieces of space junk into the neighborhood of the International Space Station and its residents, Mike Foale and Alexander Kaleri.

An even more serious threat came in November 2001 when another Russian satellite inexplicably shattered into at least 300 pieces within 18 miles of the station. Almost half crossed paths with the outpost.

Flying as fast as six miles per second, a tiny fragment of aluminum could strike the station with the same force as a rifle bullet.

NASA risk analyses show that micrometeorites and space junk pose one of the greatest dangers to the $100 billion station. Yet, agency records show most of the Russian half of the outpost, including the station crew quarters and emergency lifeboats, fail to meet NASA safety standards.

More alarming, there is a 22 percent chance that debris will puncture the hull of a Soyuz crew escape ship during the course of 15 years. Russian Federal Space Agency officials insist their station modules are strong enough. Three decades of experience operating space stations proves it, they say.

"The Russian standing on this matter is firm," said Yuri Karash, an expert on U.S.-Russian space cooperation and a member of the K.E. Tsiolkovskiy Russian Academy of Cosmonautics. "All Russian space hardware does meet reasonable requirements of anti-meteorite defense, providing an acceptable degree of safety for its crews."

The U.S.-Russian debate on the matter has been contentious.

"The Russians have been quite annoyed by their U.S. colleagues raising this issue again and again," Karash said. The two sides nevertheless are working on the issue. The Russians agreed to shore up the crew quarters with extra shielding. Spacewalking astronautsinstalled some extra shields in 2001, but work to strengthen the module will not be done until at least 2006.

Plans also call for outfitting Soyuz lifeboats and Progress supply ships with protective blankets made of bulletproof fabric. In the meantime, leak-detection gear and patch kits have been sent up to the station. Crews also are being trained to fix small leaks and, if necessary, evacuate the outpost.

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