Mystery objects redux

A flight controller at NASA's shuttle Mission Control room spotted the debris at about 2:45 a.m. EDT (0645 GMT) Tuesday while using one of the orbiter's payload bay cameras during routine Earth observations, shuttle officials said.

Image analysts were unable to identify what the mystery object was, and likely will not be able to, shuttle officials said, though some engineers think it could still be a small piece of plastic inadvertently left between tiles along Atlantis' underbelly.

"We don't know that for sure, but it is a likely candidate," Hale said, referring to the bit of orange plastic--known as shim stock--seen dangling from a gap between the protective heat tiles along Atlantis' belly.

But a second object photographed by Atlantis' crew is thought to be a simple plastic bag that drifted away from the orbiter.

"We do see things come off space vehicles from time to time that are really of no consequence other than we really would not like to leave litter lying around," Hale said.

Data indicating eight potential impact sites within two minutes, based on new accelerometer sensors within the leading edge of one of Atlantis' wings has been put to rest, Hale said, adding that they signals correspond to powerful movements of the shuttle's elevons.

The elevons are used to help steer the orbiter when it flies through Earth's atmosphere during reentry, and are powered by hydraulics.

Flight controllers on Earth conducted a camera survey of Atlantis' payload bay and upper orbiter surfaces while the shuttle's STS-115 crew slept, which will cut down the amount of time the astronauts spend on robotic operations on Wednesday.

"We have, through inspection of the orbiter, cleared many areas of the orbiter," Hale said of that work, adding that thermal analysis have also found no signs of any abnormal variations along the orbiter's hull. "In terms of making sure that the shuttle is safe for entry, that's our primary goal and we will know that at the end of the crew's day tomorrow."