Flying atop the modified Zenit rocket will be an American-built communications satellite that its London-based owners hope will heal the financial woes that forced them last August to declare bankruptcy.

"The launch of [our] first satellite will represent a tangible milestone for our employees, our vendors and our company, which has undergone a transformation over the past six months," said Richard Greco, chief executive of ICO Global Communications Ltd.

With the launch of their first satellite, the London-based firm will begin testing their concept for competing in the still-emerging market of providing worldwide cellular telephone service using satellites orbiting Earth.

ICOs competition includes Iridium LLC of Washington, D.C. who is also restructuring after declaring bankruptcy in 1999 and Globalstar Telecommunications Ltd. of San Jose, California, who recently finished orbiting all 48 of its satellites and has begun offering service.

ICOs approach to providing global cellular phone service is slightly different than the other two companies. Instead of orbiting dozens of smaller satellites in low Earth orbit, ICO plans to launch 12 larger satellites into whats being dubbed "medium Earth orbit" some 6,000 miles (9,656 kilometers) high.

This first satellite will fly alone for at least six months while engineers test its systems and capabilities. Additional satellites will then follow, flying on Boeings Delta 3, Lockheed Martins Atlas 2-AS and Krunichevs Proton rockets.

The Sea Launch fleet, which includes the launch platform and a launch control support ship, arrived on station at the equator early Thursday and the crew immediately began final launch preparations.

Those preparations include filling the launch platforms ballast tanks with 20,000 tons (20.3 million kilograms) of water so it slightly sinks. The heavier platform with its lower center of gravity then provides an ideal launch pad for the modified Zenit rocket, Bejmuk said.

Sea Launch is an international venture with commercial partners from the United States, Russia, Ukraine and Norway. A demonstration launch and the first commercial mission flown in 1999 both were a success.

Sundays late morning space shot is to be the third in a string of launches targeted for launch this weekend.

Also set to go is a Russian Proton rocket from Kazakstan around 11 p.m. EST Saturday night (Sunday morning, 4:00 GMT) and an Orbital Sciences Taurus rocket from Vandenberg Air Force Base, California, on Sunday between 4:23 and 4:50 a.m. EST (9:23 and 9:50 GMT).

The Sea Launch mission has a launch window of only five seconds, so it will either launch at 10:49 a.m. EST (15:49 GMT) Sunday or wait 24 hours to try again, but mission officials arent concerned.

"Our experience is that once we enter our automatic countdown we are able to arrive at the launch time with a great deal of precision," Bejmuk said.