NASA Delays Mars Probe's Launch, Eyes Shuttle Cabin Leak

NASA delayed the planned launch of its Phoenix Mars lander by 24 hours Tuesday as engineers trace an apparent cabin leak aboard the shuttle Endeavour for a separate spaceflight.

The two closely-spaced missions are slated to launch within days of each other from Cape Canaveral, Florida, with Phoenix initially targeted for an Aug. 3 launch and Endeavour's STS-118 astronaut crew aiming for an Aug. 7 liftoff.

But the threat of poor weather Tuesday prevented pad crews from fueling the second stage of the Delta 2 rocket to launch NASA's Phoenix probe towards Mars from the Cape Canaveral Air Force Station. The delay forced mission managers to reset the planned launch for Saturday, Aug. 4 at 5:26:34 a.m. EDT (09:26:34 GMT).

"Thunderstorms are rolling in so we're rescheduling the fueling for [Wednesday] morning," NASA spokesperson George Diller, at the agency's nearby Kennedy Space Center (KSC), told SPACE.com. "There's not enough contingency time to get to the third, so we're slipping one day."

NASA's Phoenix lander is designed to study the northern polar regions of Mars using a robotic, shovel-like scoop to dig into the martian terrain and analyze the planet's water ice. NASA must launch the $420 million mission within a 22-day window that closes Aug. 24 or else wait another two years until Mars and Earth are in the proper orbital positions for another attempt, mission managers have said.

Given Phoenix's limited launch window, NASA space shuttle program managers have said the Mars mission is a high priority and could prompt a few days of delay for Endeavour's own August liftoff. Currently, the Phoenix probe has launch opportunities through Sunday before any shuttle delays would be required.

"It's still too early to tell," NASA spokesperson Tracy Young, of KSC, told SPACE.com on whether a shuttle launch delay may be needed.

Meanwhile, engineers are continuing efforts to pin down an apparent leak somewhere within Endeavour's crew cabin or the pressurized SPACEHAB cargo module in the orbiter's payload bay.

Young said engineers found signs of the leak over the weekend and initially attributed it to a loose hose fitting on ground equipment. But the problem persisted after the hose fitting was addressed, leaving engineers once more scanning the crew and cargo module, as well as the pressurized tunnel and hatches running between them, for signs of the leak.

"Right now we're troubleshooting and engineering is evaluating it to try to isolate the problem," Young said.

Commanded by veteran shuttle flyer Scott Kelly, Endeavour's STS-118 mission is set to deliver a hefty load of cargo, spare parts and a new piece of the space station's starboard-side framework. The up-to-14-day mission will mark the first flight for teacher-turned-spaceflyer Barbara Morgan, NASA's first educator astronaut.

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