The seven astronauts aboard the shuttle Endeavour are hoping for clear skies over Florida today as they prepare to land after a marathon flight to the International Space Station.

Endeavour is slated to land at NASA's Kennedy Space Center in Cape Canaveral, Fla., at 10:48 a.m. EDT (1448 GMT) with favorable weather expected. There is a slight chance that rain or thunderstorms may stray too close to the shuttle runway, but the astronauts and Mission Control are optimistic the good weather will hold.

"I'm ready to get back," Endeavour commander Mark Polansky said in a televised interview Thursday. "Personally I really miss my family, so I'm looking forward to seeing them."

Headed home

Polansky and his crew are returning to Earth to complete a grueling 16-day mission to the International Space Station, where they replaced a member of the outpost's six-man crew and delivered a brand new experiment porch for the station's $1 billion Japanese Kibo lab. They also performed five challenging spacewalks - tying the record for most ever at the station during a shuttle flight - to install the porch, replace aging solar array batteries and deliver vital spare parts.

The mission also temporarily boosted the station's population up to 13 people - its highest ever - for the first time. The station increased its crew size from three to six people in late May, with the seven astronauts on Endeavour more than doubling that when the shuttle arrived.

It's not the last time so many people will gather in space - NASA's next shuttle mission slated for late August will do the same. Endeavour astronauts said that, in general, the station was a comfortable place, even with 13 people in close quarters.

"It is immense for a space vehicle," said Canadian astronaut Julie Payette Thursday. "There was room for everybody, we could spread out."

One of the station's two space toilets and a carbon dioxide removal device broke down during the mission. Both were swiftly repaired, though the carbon dioxide scrubber shut down again Wednesday. Station astronauts are expected to complete a new repair this afternoon.

Returning to Earth with Polansky and Payette are shuttle pilot Doug Hurley and mission specialists Chris Cassidy, Tom Marshburn, David Wolf and Japanese astronaut Koichi Wakata.

Wakata is headed home after living aboard the station for 4 1/2 months as Japan's first long-term space resident. He arrived at the station in March on a different shuttle and was replaced during Endeavour's flight by NASA astronaut Tim Kopra. Wakata said he longs to taste sushi again and take a refreshing dip in Japan's hot springs.

Landing options

Endeavour actually has two chances to land today, both of them in Florida. In addition to the 10:48 a.m. EDT (1448 GMT) opportunity, the shuttle could also try for a 12:22 p.m. EDT (1622 GMT) return if weather thwarts the first attempt.

The weather forecast from NASA's Spaceflight Meteorology Group at the Johnson Space Center in Houston predicts a slight chance of rain and thunderstorms within 30 miles (48 km) of Endeavour's Florida runway. The chance of rain is expected to increase later for the second opportunity.

But the observed weather at the landing site in recent days has been favorable at the time Endeavour is expected to touch down, NASA flight director Bryan Lunney told reporters Thursday.

"It's Florida. It's summer. So there's always, in my mind, kind of a chance of rain there," Lunney said. "Right now...things are looking really good for us."

If Endeavour cannot land today, NASA would activate a backup runway at Edwards Air Force Base in California land Saturday for sure. The weather in California is favorable for both Friday and Saturday. Endeavour has enough supplies to last until Sunday, but NASA typically keeps one day in reserve in case of an unexpected glitch.

NASA prefers to land Endeavour in Florida, which is the launch site and home port of its three-shuttle fleet. A landing in California can add up to a week of time and $1.8 million in transport costs to ferry shuttles back to the spaceport from California atop a modified 747 jumbo jet.

Endeavour's STS-127 mission to the space station is NASA's third of up to five shuttle flights planned for this year.

• Video - Space Station's Population Boom
• Video - The Kibo Lab: Japan's Hope in Space - Part 1, Part 2
• SPACE.com Video Show - The ISS: Foothold on Forever

SPACE.com is providing continuous coverage of STS-127 with reporter Clara Moskowitz and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed. Live landing coverage begins at 7:30 a.m. ET.