CAPE CANAVERAL, Fla. A quintet of astronauts will climb aboard a fully-fueled shuttle Endeavour tonight, aiming to take off on a mission that promises to pave the way to the start-up of scientific research on the International Space Station.

The 18-story shuttle and its five-man crew which includes four American astronauts and a Canadian mission specialist remain scheduled for a thundering nighttime spectacular at 10:06 p.m. Eastern Standard Time (Friday, 03:06 GMT).

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The final stages of a three-day countdown will pick up at Kennedy Space Center (KSC) a few hours earlier, and forecasters are calling for near-perfect weather for the planned launch from NASAs central Florida spaceport.

"It looks like [it] will be a beautiful night for launch," NASA Test Director Steve Altemus told reporters here Wednesday. "And the launch team is looking forward to doing their part in continuing the station assembly sequence."

Look for live coverage of the final countdown and launch which will be broadcast on NASA TV and carried live on SPACE.com to begin at 5 p.m. EST (22:00 GMT).

Riding along with the astronauts: a $600 million power tower critical to the $60 billion station construction project; a joint effort of 16 nations and 100,000 workers on four continents.

The stations electrical power supply now is so sparse that its first tenants U.S. astronaut Bill Shepherd and two Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev are restricted to working within just two of the outposts three pressurized wings.

And more electricity is a must before the stations first research lab a bus-sized U.S. module that will serve as the scientific heart of the growing complex -- can be delivered early next year.

"You couldnt bring up the lab without it," Endeavour mission specialist Carlos Noriega told SPACE.com in a recent interview. "And if you dont have the lab, you dont have any place to do science."

Weighing some 17 tons, the power tower also known as the P-6 Integrated Truss Structure houses a massive set of solar panels that will stretch 240 feet (73 meters) from tip to tip once unfurled in space.

Mounting and activating the power tower, however, will be no easy task. Noriega and shuttle crew mate Joe Tanner plan three spacewalks primarily aimed at doing that job.

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The outpost construction workers will be wearing specially designed "helmet-cams" during the spacewalking excursions, which also will be broadcast live on SPACE.com.

Space station project scientists, meanwhile, will be keeping close tabs on the mission, anxiously waiting for the shuttle crew to deploy the huge solar panels.

Research aboard the station to date has been severely limited by both the lack of power and the absence of a laboratory, so the Endeavour flight represents a make-or-break mission for scientists around the world.

"Weve been waiting for this to happen. Weve now had a few payloads on orbit, and I kind of think of these as the appetizer," senior NASA scientist John Uri said. "The main course is about to hit us with a fury, and there will be lots of courses to chose from."

Endeavour and its astronauts now are scheduled to dock at the station Saturday. The first of the three spacewalks is set for Sunday, with the two others taking place next Tuesday and Thursday, respectively.

NASAs 101st shuttle mission which will be the 15th flight of Endeavour is scheduled to last 10 days, 20 hours and 19 minutes. An on-time launch tonight would lead to a 6:19 p.m. EST (23:19 GMT) Dec. 11 landing here at KSC.