NASA counts down toward Saturday shuttle launch

CAPE CANAVERAL, Florida -- NASA is counting down toward the weekend launch of space shuttle Endeavour.

The countdown clocks began ticking Wednesday morning. Endeavour is slated to blast off Saturday on a space station construction mission. Forecasters put the odds of good launch weather at 90%.

The flight comes less than three weeks after NASA's last shuttle trip involving the successful overhaul of the Hubble Space Telescope. The highlight of this 16-day mission will be the completion of a huge Japanese lab.

It will mark the first time 13 people are together in space at the same time. Six people now live at the space station; they will be visited by seven shuttle astronauts.