The crew of the space shuttle Discovery today deployed a second communications satellite into orbit, clearing the cargo bay for the two derelict satellites they will try to capture Monday and Wednesday and return to Earth for repairs.

"The second satellite is on its way," astronaut Dale A. Gardner said this morning after deploying for the U.S. Navy a satellite called Leasat over the Pacific Ocean on Discovery's 33rd Earth orbit.

Less than an hour later, Gardner and his four crewmates watched from 16 miles away as Leasat's onboard engine kicked in and began to take the satellite toward its destination 22,400 miles above the Equator east of Brazil.

"We saw a complete engine burn this time," Gardner radioed the Mission Control Center in Houston. From Houston, astronaut David Hilmers replied, "That's good news. Looks like you're two for two."

Two for two is what the crew of Gardner, Frederick H. Hauck, David M. Walker, Joseph P. Allen and Anna L. Fisher also want to be next week when they try to salvage two satellites that have been circling Earth aimlessly since February when their engines flamed out and left them useless for radio communication with earth.

Once Discovery's cargo bay was free of the two satellites carried up on this flight, the crew began preparing for the first salvage rendezvous Monday, with the Palapa satellite once owned by Indonesia. Palapa's title now belongs to the insurance companies that paid Indonesia $90 million for its loss. The underwriters hope to reduce that loss by salvaging and selling the satellite to the highest bidder.

At noon today, Palapa was in an orbital path 30 miles above Discovery and 5,400 miles ahead of it. Westar VI, once owned by Western Union Co. and the second satellite to be salvaged next week, is in the same orbit as Palapa but 715 miles in front of it.

"We're catching up with Palapa at the rate of about 195 miles every time we circle the earth," Flight Director Larry Bourgeois said at Houston's Johnson Space Center. "We're right on the money."

Two nuisances cropped up in space today.

After one of the maneuvers a forward engine thruster began to leak toxic hydrazine fuel. Flight Director Bourgeois said, "I use the term leak loosely. It's more like a dribble. We can't even detect it on our fuel gauges. The only way we can see the leak is that the temperature on the jet nozzle changed.

"We might have to isolate that manifold . . . on Monday," Bourgeois said, "but I doubt it, at this leak rate."

The second was more of a nuisance. When astronauts Allen and Gardner began checking out their spacesuits this afternoon, they discovered that two of their four helmet lights would not go on.

When flight engineers read them procedures for fixing the lights, Allen and Gardner found that the other two lights on their helmets went out the minute they did the repairs.

Engineers in Houston decided that the astronauts were draining the helmets' batteries and told them to hold off while they figured out a new scheme.

"Anna, Dave and I just volunteered the batteries out of our wrist watches, and Joe volunteered the battery out of his hearing aid," Gardner said.

Replied astronaut Jerry Ross from Mission Control: "Forget it, it's not worth it. Besides, we want Joe to be able to hear."

Bourgeois described the possible loss of the helmet lights as nothing more than a "minor inconvenience."

"That's all it is, because we still have the flood lights in the cargo bay, flashlights from inside the cabin and a docking light we can move around to help the space walkers see in the dark. Anyway, we're still troubleshooting it, and we could easily recover those lights."

With their helmet lights on or off, astronauts Allen and Gardner are to step into the cargo bay at 8:30 a.m. EST Monday. The following six hours or more will determine the success or failure of the first commercial salvage operation ever attempted in space.

Allen is to put on the jet-powered backpack pioneered by two previous shuttle crews and cruise up to the Palapa satellite, which should be hovering a scant 35 feet over Discovery's open cargo bay.

Wearing a space backpack, Allen is to fly over to one end of the slowly spinning satellite and insert a 6-foot probe into the bell-shaped rocket nozzle. When he feels that it is secured, Allen will fasten himself to the satellite by tightening a ring on the end of the probe (called the "stinger") onto the rocket bell.

Then he is to use the thruster jets on his backpack to rotate himself counter to the satellite's spin to stop it. Allen then is to begin pushing down toward the shuttle's cargo bay, bringing the satellite with him.

In the cargo bay, with his feet fastened firmly by restraints, Gardner is to wait with a tool resembling garden shears. As Allen rides in on top of the satellite, Gardner is to use the shears to cut off a graphite mast holding the satellite's antenna. The antenna must be removed if the satellite is to fit into the cargo bay when its doors are closed next Friday for the return to Earth.

Meanwhile, astronaut Fisher is to use the shuttle's 50-foot mechanical arm to fasten onto the "stinger" holding Allen to the satellite. Once that is done, Allen is to back off and join Gardner in the cargo bay to wrestle the satellite into position on the cargo-bay floor.

The two astronauts outside are to turn the satellite over 180 degrees so that, from within, Fisher can use the arm to hold the satellite while the outside astronauts fasten it to the cargo-bay deck.

The final salvage event is to be the closing of three electrically driven bolts that are to hold the satellite down for the ride back to Earth.