Try, Try, Try, Try Again, and Discovery Finally Lifts Off : Space: The shuttle gets off the ground after three miscues. A communication satellite is launched. Five astronauts are happy to be aloft at last.

On its fourth try, the space shuttle Discovery roared away Sunday with five astronauts who dispatched an experimental communication satellite after overcoming last-minute trouble.

They were jubilant to be in space at last.

“Hey, Houston, I gotta tell ya, you’ve never seen five happier guys up here,” commander Frank Culbertson Jr. told Mission Control shortly after reaching orbit. “It’s been a long time coming.”

The astronauts accomplished one of their chief jobs when they ejected the Advanced Communications Technology Satellite. They had to delay its release by 1 1/2 hours, or one orbit, because of a temporary halt in communication from the ground to Discovery.

An attached rocket fired less than an hour later and propelled the satellite from Discovery’s 184-mile altitude to an orbit 22,300 miles high at the farthest ends. A motor firing Tuesday should circularize the satellite’s elliptical orbit.

Discovery’s flight had been delayed five times since mid-July for equipment failures, payload concerns and even a meteor shower. Two of the three earlier countdowns had been halted in the final 19 seconds.

This time--countdown No. 4--everything worked and Discovery rose promptly at 4:45 a.m. PDT from its seaside launch pad.

Two engine pump sensors failed on the way up, but that posed no problem since identical sensors worked fine, launch director Bob Sieck said. If one of those sensors had failed before liftoff, however, it would have meant another aborted launch. A broken fuel-flow sensor caused last month’s engine shutdown three seconds before liftoff.

It is NASA’s 57th shuttle mission and the fifth this year.

Besides deploying the communication satellite and an ultraviolet telescope, the crew is to conduct a six-hour spacewalk to test tools needed for the Hubble Space Telescope repair mission in December.

Thursday’s spacewalk by James Newman and Carl Walz will be NASA’s last before tackling Hubble. Five and possibly seven spacewalks are planned for the telescope repair mission.

The satellite carried up by Discovery, called ACTS, is designed to transmit data 20 times faster than present craft. Project managers said that it could, one day, shrink the size of satellite dishes to 1 1/2 feet in diameter.

Discovery’s 10-day mission is due to end Sept. 22 in Florida.