NASA officials canceled today's Space Shuttle Endeavour launch after workers discovered a hydrogen gas leak during fueling, Space.com reports. If the failure is fixed soon, the seven-member crew could lift off from Cape Canaveral, Fla., as early as tomorrow morning, when near-perfect weather is expected. Discovery's STS-119 launch was delayed with a similar glitch 3 months ago, but launched successfully after repairs.
Led by veteran flyer Mark Polansky, Endeavour's crew plans to haul a Japanese-made porch to the International Space Station's huge Kibo laboratory. The long 16-day mission will also replace Japanese astronaut Koichi Wakata, who has lived in the lab since March, with newbie space traveler Tom Kopra.