They have a long Super Bowl today ahead as they prepare to venture outside the orbital laboratory for their second spacewalk in less than a week. For today's space marathon, the cooling system work is the primary activity of the two spacewalkers, who stepped out of the hatch at 8:38 AM EST (1907 IST). The walk is expected to last for 6.5 hours.

More than two hours into today's spacewalk, International Space Station (ISS) spacewalkers, clad in bulky NASA spacesuits, spotted a tiny leak of toxic ammonia coolant in the form of pinpoint-like flakes.

"They're tiny, little, tiny flakes," Lopez-Alegria said, adding that the bits of frozen ammonia were nowhere near the size of flakes seen during a January 31 spacewalk that prompted minor clean up activities. "They look like pinpoints." The tiny leak came as the Expedition 14 spacewalkers finished up one of four cooling line reconnections during today's spacewalk. The cooling system work is the primary activity of today's spacewalk.

Flight controllers at NASA's Mission Control in Houston gave Lopez-Alegria and Williams a go ahead to continue with their cooling system task and to remain vigilant and alert for any signs of additional ammonia leaks.

The third spacewalk, set for Thursday, would mark the first time three spacewalkers have conducted such a mission in a short time at the space station without a space shuttle docked to it.