Zarya and Unity modules of ISS orbiting Earth. Photo: NASA

The space shuttle Atlantis, fresh from a major overhaul but beset by a string of last-minute delays, is finally ready for blastoff April 24 on an impromptu space station repair mission.

Carrying new batteries, additional fans, smoke detectors, electronic gear and other equipment needed by the Russian Zarya module, Atlantis and its seven-member crew are scheduled to take off from pad 39A at the Kennedy Space Center at 4:15 p.m. EDT (2015 GMT) to begin a planned 10-day mission.

You can follow the countdown live in our Mission Status Center. We will provide continuous play-by-play reports during the final hours of the countdown and the entire 10-day shuttle flight.

If all goes well, Atlantis will dock with the international space station two days later -- on April 26 -- setting the stage for a spacewalk by astronauts James Voss and Jeffrey Williams the next day to install equipment on the outside of the unfinished lab.

The day after that, on April 28, the crew will enter the station to begin four busy days of repair work to bring the Zarya module back up to specifications. The flight plan calls for Atlantis to undock from ISS on May 2 and to land back at the Kennedy Space Center two days later.

"This certainly is an exciting time we live in in the international space station program," said Tommy Holloway, the man who runs the station project for NASA. "We're ready to continue the creation of ... a station that will provide world-class research capability, opportunities for discovery and progress in human space flight that our minds have not imagined. The international space station will also provide the bridge to a future that will enable human exploration of our solar system and perhaps even beyond."

But it will take four more years -- and 39 shuttle flights, eight major Russian launches and dozens of Russian Soyuz and Progress refueling flights -- to complete the $60 billion laboratory. At present, the station consists of a Russian module called Zarya and a multi-hatch node called Unity, supplied by NASA, that eventually will serve as a gateway to other modules. Both were launched in late 1998.