The four-man crew of the space shuttle Columbia continued its performance today as the Space Age's first orbital deliverymen, successfully releasing into space a second massive communications satellite brought from Earth on Thursday.

For the second straight day, astronauts Vance Brand, Robert Overmyer, William Lenoir and Joseph Allen stepped without a stumble through the difficult task of launching a satellite from the shuttle. This time, they even counted down the launching the way it's done on Earth, and performed the launching to the theme music from the movie "2001."

"We're two for two; we deliver," astronaut Allen called down from Columbia as it crossed the eastern Pacific Ocean on its 22nd revolution of Earth. Chimed in astronaut Lenoir, who with Allen supervised both satellite deployments: "To quote that famous Joe Allen, we haul and we deliver."

The satellite deployed out of Columbia's cargo bay today belongs to Telesat of Canada. It will serve the television and telephone needs of all of Canada for the next 10 years.

Almost a twin of the Thursday satellite owned by Satellite Business Systems of McLean, Va., the Canadian satellite, which is called Anik and means Little Brother in Eskimo, used its own rocket to climb to a higher altitude where it will position itself next week over the equator on a straight line to the Canadian Rockies.

Once again, the astronauts televised their satellite deployment back to Earth, with astronaut Allen starting the countdown from the arbitrary number 17 while the satellite spun 50 times a minute in the cargo bay so it would not tumble on its way out. Just as he reached "one" the huge blue cylinder rose up majestically out of the bay to the lofty theme music from "2001."

"Did you like the countdown audio or the music audio?" Allen asked impishly.

"We're polling the audience on that," astronaut Brian O'Connor replied with mock severity from the Mission Control Center at the Johnson Space Center.

"Seriously, Joe," O'Connor went on, "everybody down here's got a lot of smiles on right now. We'll be toasting you folks tonight."

Rarely has a space flight gone better than the first two days of this one, which is remarkable because it is only the fifth flight Columbia has made and its first operational flight.

So little trouble has been encountered so far that astronaut Robert Stewart told shuttle pilot Overmyer from Mission Control this morning that he is beginning to be bored.

"I want you to know," Stewart said, "that you guys have provided us with one of the most boring shift changes briefings I have ever gone through here."

While they may have been working together smoothly, the four astronauts were apparently getting into each other's way from time to time.

This is the first four-man crew in U.S. space history, and Columbia's cabin is so crowded with instruments that space is tight. This came home loud and clear when an unidentified member of the crew bumped Pilot Overmyer a little too hard with the wrong part of his anatomy.

"Say, you got your rear end in my head right now," said Overmyer, who is a colonel in the Marine Corps. From a disembodied voice came the standard astronautical reply of unconcern:

"Sorry about that."

Crowded as they might be, the "gang of four" -- as they sometimes call themselves--was settling down to space flight as comfortably as any in memory.

None has complained about trouble sleeping or the least bit of motion sickness. They all said they were eating well and even enjoyed the spicy jalapenos they were carrying in their food lockers.

The astronauts are to get an easier day on Saturday, after two straight 18-hour workdays.

Most of the day they will spend getting ready for Sunday, when Allen and Lenoir put on space suits and take a three-hour walk outside the spaceliner from one end of the cargo bay to the other.

It will be the first time any shuttle astronauts have ventured outside Columbia and the first walk in space since two Skylab astronauts did it eight years ago.