BAIKONUR, Kazakhstan A long-stalled bid to build a global village in space got a huge boost today as the International Space Stations crew quarters finally rocketed into orbit, heralding the start of a make-or-break mission for the $60 billion construction project.

Riding atop a Russian Proton rocket, the all-important Russian service module dubbed "Zvezda," or "Star" blasted off at 12:56 a.m. Eastern Daylight Time (04:56 GMT) from Baikonur Cosmodrome in Kazakhstan.

Still to come, however, are two weeks of orbital testing and then a tricky July 25 docking at the international station. Independent aerospace experts expect some anxious moments between now and then.

"Lets face it: This is the big one," said Jerry Grey, director of aerospace and science policy for the American Institute of Aeronautics and Astronautics.

"This particular part of the station is fundamental to the whole construction project and its also the one single, potential point of failure," added David Webb, a space policy analyst who served on the U.S. National Commission on Space during the programs infancy.

A Proton rocket launches with the Zvezda service module aboard. SPACE.com photo by Anatoly Zak.

"So this mission, in a sense, is like crossing a huge river. If we make it, were pretty much home free. But if we dont, I see a lot of trouble for the entire space program."

Even NASA Administrator Dan Goldin urged all involved to stay focused on the days ahead.

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"Now before we pop champagne corks, I caution all of us: We have two more weeks of operations before we dock," he said. "But I have a sense everything will be okay."

A small space station unto itself, Zvezda is considered the key building block that will enable a 16-nation consortium to erect a 480-ton research complex spanning an area nearly as large as two football fields.

About the size of a Greyhound bus, Zvezda is meant to serve as an initial command post and living quarters at the now vacant station, which currently consists of an American docking module and a Russian space tug that is running low on fuel.

A Pizza Hut logo appears on the side of the Proton rocket flying the Zvezda service module, part of Russia's space commercialization efforts to pay for programs.

It also is equipped with the propulsion system that will be needed to keep a growing outpost aloft during five more years of construction and a subsequent decade of scientific research.

"The Zvezda module is what I like to call the heart and soul and the brains of the space station," said U.S. astronaut Ellen Baker. "And we cant send a crew up there unlessZvezdais docked and functioning."

Consequently, the next two weeks will be crucial for the station project an endeavor so complex it often is compared to raising the Great Pyramids of Egypt.

Russian ground controllers this week will begin periodic firings of Zvezdas on-board engines to maneuver the 43-foot (13-meter) module closer and closer to the international station.

At the same time, flight controllers will turn on and test Zvezda's systems to make sure all are working properly before they attempt a remote-control docking with the station at 9 p.m. EDT July 25 (July 26, 01:00 GMT).

The docking is considered so crucial that two cosmonauts are standing by to lift off aboard a Soyuz rocket and manually link the service module to the station if the situation arises. In the worst case: if both the automatic docking and the back-up scheme with the cosmonauts fail, the entire station construction project could be in peril.

"This is an absolute critical step, obviously," Baker said. "If were going to have a permanent presence in space, if were going to have a crew in space at all times on board the space station, this module must get up there, must dock and must function well."

The fledgling station has already been on hold now for 19 months, due largely to Zvezda's launch delays. If Zvezda fails to dock with the outpost, station construction would be delayed until next April at the earliest.

The first full-time station crew now scheduled to board the outpost in November wouldnt fly for another three years the time it would take to build a replacement for Zvezda or outfit a U.S. lab with crucial life-support equipment.

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And Russias participation in the project which has been the subject of ongoing controversy in the U.S. Congress would be called into question while officials in Moscow debated whether Russia could afford to fulfill its costly program obligations.

Senior officials with the Russian Aviation and Space Agency (Rosaviacosmos) are hesitant to even contemplate a future that grim.

"At this point, I dont want to talk about such unpleasant things," Mikhail Senelshchikov, chief of piloted space flight with Rosaviacosmos, told reporters at a prelaunch news conference.

Russian Space Agency director Yuri Koptev, left, and NASA Administrator Dan Goldin appear in a press conference after the July 12, 2000 launch of the Proton rocket carrying the Zvezda service module.

NASA officials and independent aerospace experts prefer to look on the bright side, too. A successful docking, they note, essentially would jump-start the stalled construction project.

Nine station construction missions would be launched aboard U.S. space shuttles between September 2000 and September 2001.

A trio of resident crews would fly up to the station and back to Earth during that time, and the outpost would start blossoming into a fully-functional, state-of-the-art research complex some 250 miles (400 kilometers) above the planet.

"If this all is successful and God, we hope it will be were in the ball game again," Webb said.

Thats not to say, however, that the road ahead will be an easy one.

Another 39 U.S. shuttle flights and seven Russian rocket missions will be needed to haul nearly 100 more major station components up to a construction site some 240 miles (384 kilometers) above the planet.

U.S. astronauts and Russian cosmonauts face some 1,700 hours of dangerous spacewalking construction work to complete the outpost, and dozens of refueling and resupply missions will have to be successfully staged during the course of the project.

Complicating matters is the international nature of the work, which involves some 100,000 workers from 16 nations on four different continents.

And considering the difficulties encountered to date, not even the highest-ranking project officials expect the remainder of the complex job to come off without a hitch.

"We have covered a very long road [to date]. We wish this road had been a highway, but highway it was not," said Rosaviacosmos Director General Yuri Koptev.

"It was oftentimes closed for repairs. We have experienced detours, bumps and holes and what-have-you. But [station project partners] understand only too well that hurdles are inevitable. And it is essential on such occasions to put our heads together, and through a joint effort, overcome those hurdles."

Goldin agreed.

"We are going to have more problems. We are going to have more difficulties," he said.

But the end result, he predicted, will be an orbiting research complex that will give the human race a foothold in space and a steppingstone to frontiers further out in the cosmos.

"The space station is going to be built, and then were going to figure out how people live and work in space," Goldin said. "And we will get to Mars."