The homecoming for the international space station's former crew was delayed by at least a day as wind, clouds and showers canceled space shuttle Endeavour's landing opportunities on Monday.
"Tell everybody waiting on the ground we're sorry, we'll try to see them tomorrow," said shuttle commander Kenneth Cockrell.
"We gave it a good college try today. But those thunderstorms are starting to encroach," Mission Control responded.
The shuttle had two chances to touch down on Monday at the Kennedy Space Center in Florida. But both were scrubbed because of weather that got worse as the day progressed.
Endeavour is bringing back space station Alpha's former crew of American astronauts Daniel Bursch and Carl Walz and their Russian commander, Yuri Onufrienko, who have been in orbit for more than six months.
The delay added another day to the record that Bursch and Walz now hold for the most time ever spent in space by Americans in a single stretch. Monday was the 194th day in orbit for the returning space station crew. The old American record was 188 days.
Forecasters had not been expecting good weather on Monday.
The shuttle will try landing in Florida on Tuesday, but the forecast was not much better, with a chance of rain.
A backup landing site at Edwards Air Force Base in California could be called up Tuesday. The shuttle can stay in orbit until Thursday.
Endeavour left space station Alpha on Saturday after delivering a new crew and retrieving Bursch, Walz and Onufrienko.
All three men, who are in their 40s, face weeks of rehabilitation upon their return. They exercised each day on the space station, but muscles and bones weaken in weightlessness, so they were expected to almost certainly feel nauseated and wobbly when they return.
The new space station crew of two Russians and one American will remain on board until October.
While Endeavour was docked to Alpha, two shuttle astronauts performed three spacewalks to replace a wrist joint on the space station's 58-foot robot arm, install a movable platform for the arm and do other work.