The astronauts on the International Space Station are currently assessing the situation with mission managers on the ground and are to decide what could be done after two major problems were found. The astronauts found a 2.5-foot-long (75-cm) rip in the station's solar panel that occurred while it was being unfurled on Tuesday.

"Until we know what we think the cause is, maybe until we get some better pictures, I don't think we really have any solid leads on how to fix it yet," space station flight director Heather Rarick said late Tuesday.

The unexpected incident determined the postponement of the next spacewalk from Thursday to Friday, at the earliest, and will almost certainly involve work with the station's ripped solar wing. Because the astronauts had to stop the solar panel from fully extending, the Space Station is not as stable as it should be. The wing on the other side extended without any glitches, which means there is a slight imbalance.

"I think we're kind of in the groove right now, so if the ground decides that's the right thing to do and they ask us to do it, we'll be ready to support it," shuttle commander Pamela Melroy said.

On Sunday, Scott Parazynski and Dan Tani spent six and a half hours outside the station uncoupling the 17,500-kilo module with the aid of the station's robotic arms, controlled by colleagues inside.

However, they have found a significant problem. A joint that turns a pair of the station's solar wing panels so they can track the sun for energy is malfunctioning. The motors operating the joint were previously determined to draw more power than expected, and produced suspicious vibrations.

Dan Tani did not find a protruding bolt, as some NASA engineers had expected, but found instead metal shavings inside the joint. He collected a sample to be analyzed back on earth. "It's quite clear," Tani told Mission Control, "there is metal-to-metal scraping and it's widespread. Wow."

For the Discovery this is the twenty-third mission to the International Space Station. Discovery delivered its precious cargo, the U.S. Node 2 Harmony module, which expands the space station's capability for future international laboratories. Built in Italy for the United States, Harmony is a high-tech hallway and Tinker toy-like hub. It is a 23- by 14-foot passageway that will connect the U.S. segment of the station to the European and Japanese modules, to be installed later this year and early next year, respectively.