Engineers are looking into what might have caused more than 300 microscopic leaks in the nozzle of a space shuttle main engine used to help launch Endeavour in July. But officials Friday characterized the issue as relatively minor, saying the leaks were well below any threshold that could cause an in-flight problem.

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"This mission is proceeding very well," says space station flight director Ron Spencer. "So far, the crew has transferred about 90 percent of the resupply items that were delivered in the Leonardo logistics module over to the station, and now they're primarily concentrating the rest of the mission on the return items that will come back to the ground in that module. We're about 60 percent done with transfer overall, with the stuff going to station and the stuff going back."

While the shuttle crew has been taking some time off today, some station work has been underway. The astronauts routed cables in the Harmony module in preparation for receiving the Japanese HTV cargo ship in a couple weeks and are calibrating sensors in the oxygen generation system.

The latest version of the NASA Television schedule (Rev. I) can be downloaded here.

The Discovery astronauts and their space station colleagues enjoyed a half-day off Friday, taking a break to relax and enjoy the view from 220 miles up after a grueling week in orbit resupplying the International Space Station.

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The wakeup call has been sounded to begin a light-duty day aboard the shuttle Discovery and International Space Station. The astronauts will enjoy some time during the first half of their day to rest and look out the window. Later tonight, the in-flight crew news conference is planned, followed by preparations for Saturday evening's spacewalk.

Another day is coming to a close for the STS-128 mission. The crew will be awakened to start Flight Day 8 at 11:59 a.m. EDT.

EVA ENDS. Repressurization of the Quest airlock module commenced at 12:51 a.m. EDT, marking the official end of today's spacewalk by Danny Olivas and Christer Fuglesang.

The EVA lasted 6 hours and 39 minutes. That brings the total time for the two spacewalks conducted thus far during Discovery's mission to 13 hours and 14 minutes.

The third and final spacewalk for the crew is scheduled to occur Saturday.

Additional coverage for subscribers:
VIDEO: HIGH DEFINITION DAY 6: PREPPING FOR NEXT EVA PLAY
VIDEO: HIGH DEFINITION DAY 6: MOVING FROZEN SCIENCE PLAY
VIDEO: HIGH DEFINITION DAY 6: EMPTYING OUT LEONARDO PLAY

VIDEO: OLD TANK MOVED TO SHUTTLE FOR RECYCLING PLAY
VIDEO: NEW TANK HOOKED UP TO STATION UMBILICALS PLAY
VIDEO: CHRISTER FUGLESANG CARRIES NEW AMMONIA TANK PLAY
VIDEO: PREPS IN SHUTTLE BAY TO UNPACK NEW AMMONIA TANK PLAY
VIDEO: DANNY OLIVAS FLOATS OUT OF AIRLOCK TO START EVA PLAY
VIDEO: THURSDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: STEP-BY-STEP SUMMARY OF SPACEWALK NO. 2 PLAY
MORE: STS-128 VIDEO COVERAGE
MORE: HIGH DEFINITION VIDEO COVERAGE
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The hatch is confirmed closed and locked.

The spacewalking duo is getting back into the airlock.

Tool inventories are underway as this spacewalk begins to wind down.

Some unexpected cable configurations outside the PMA No. 3 has caused Mission Control to scrub today's get-ahead task for Olivas.

Fuglesang has gotten two lens cover shields on the space station robot arm cameras.

Having successfully completed all of the planned tasks for this spacewalk with some extra time to spare, the crew is going to tackle a few get-ahead tasks before returning to the airlock. Fuglesang will install some protective lens covers around video cameras on the space station robot arm to shield them from rocket exhaust during the upcoming Japanese HTV cargo ship arrival. Olivas will work on a heater cable at the Pressurized Mating Adapter No. 3 docking port.

Mission Control just told the crew that the newly installed ammonia tank has been checked out and is doing well.

Danny Olivas is installing a grapple fixture onto the Starboard 1 truss' ammonia tank that will be removed and replace during a future space shuttle mission.

The spacewalkers have gotten about 50-55 minutes ahead of their timeline, Houston says. As such, additional activities will be added into game plan for remainder of today's EVA.

The depleted ammonia tank has been locked down in the payload bay of space shuttle Discovery for the ride back to Earth. The tank will be refurbished and refilled on the ground for its launch back to the space station next year to replace an identical reservoir on the Starboard 1 truss.

Mission Control reports that the newly installed ammonia tank has been pressurized as part of its activation sequence.

The spacewalkers are bolting the tank into place.

Four hours into today's spacewalk. Fuglesang is nearing the rear of Discovery's payload bay to deposit the spent ammonia tank. Olivas has climbed down there to assist in stowing the structure on the same bracket that carried the new tank to orbit.

The space station's robot arm is in motion for this glacial maneuver of Fuglesang down to the payload bay where the old tank will be bolted atop the carrier pallet.

Fuglesang has taken the tank away from Olivas.

The robot arm ungrasped the old tank and left the 1,275-pound structure in Danny Olivas' hands. The arm will maneuvered around for Christer Fuglesang to take the tank. The Swedish astronaut remains anchored in a foot platform on the arm.

With the new tank attached and hooked up, the spacewalkers are turning their attention to the old tank removed during the first EVA. That depleted tank has remained physically grappled on the space station's robot arm for the past two days. The arm will release the tank into the hands of the astronauts for Christer Fuglesang to hold while being flown down to the stowage platform in payload bay by the Canadian-built crane.

Installation of the new Ammonia Tank Assembly has been completed, accomplishing a major objective of space shuttle Discovery's mission. The tank contains 600 pounds of ammonia for the International Space Station's thermal control system and the cooling of onboard hardware.

The second pair of ammonia and nitrogen press lines have been connected.

The first set of connectors have been mated.

Danny Olivas is hooking up the ammonia transfer lines and nitrogen pressurization umbilicals to the new tank.

The bolts have been driven and now the tank is firmly installed in the Port 1 truss of the International Space Station.

The tank is being bolted into place.

Two hours into today's EVA. The spacewalkers are working together to get this 1,702-pound tank into its new home at the International Space Station.

Fuglesang is arriving in range of the P1 truss.

The space station's arm continues to maneuver Christer Fuglesang and ammonia tank up from the space shuttle payload bay. Danny Olivas is climbing up to the Port 1 truss to receive the tank when his crewmate arrives.

The tank has been unbolted and freed from the launch pallet that bridges across the payload bay. This boxy coolant reservoir is in the hands of Swedish astronaut Christer Fuglesang to carry up to the International Space Station while riding on the robot arm.

Now with his feet securely anchored in a platform on the end of space station's robot arm, Fuglesang is joining Olivas in releasing the bolts that hold the new tank to its carrier structure in the shuttle payload bay.

As Fuglesang gets a portable foot restraint attached to the station arm for him to stand on, Olivas is removing a thermal skirt around the base of the new coolant tank.

The first worksite for today's EVA is the rear of space shuttle Discovery's payload bay. Danny Olivas will prep the new ammonia tank for its unpacking from the launch carrier while Christer Fuglesang gets the robot arm equipment situated for him to hop aboard and then haul the tank up to the space station.

Both spacewalkers have emerged from the airlock. This is the fourth EVA for Olivas and the fourth for Fuglesang.

EVA BEGINS. The spacewalkers switched their suits to internal battery power at 6:12 p.m. EDT, marking the official start time for today's EVA by Danny Olivas and Christer Fuglesang. This is the second of three spacewalks planned during Discovery's mission at the International Space Station.

The airlock has reached vacuum and the Quest airlock's outer hatch just opened to space.

Depressurization is pausing at 5.0 psi for a planned leak check.

The internal hatch on the airlock has been closed and depressurization is underway.

The spacewalkers have gotten their SAFER backpack attachments and moved into the section of the airlock that will be depressurized.

This extra work on Olivas' spacesuit has put the spacewalk preparations about 30 minutes behind in the timeline, Houston says.

A purge of Danny Olivas' spacesuit is being reperformed.

Olivas' chin strap has been fixed and his helmet reinstalled to reseal his spacesuit.

The chin strap on Danny Olivas' communications cap has come loose. So the crew will have to interrupt spacewalk preparations to correct the problem.

With that communications cap replaced, Fuglesang's helmet has been reinstalled and his suit put through a good leak check.

The spacewalkers have gotten suited up inside the Quest module of the International Space Station. The crew was running about 45 minutes ahead of schedule. But a noise problem with the microphones on Christer Fuglesang's communications cap forced the crew to swap that out.

Astronauts John "Danny" Olivas and Christer Fuglesang are preparing for a six-and-a-half-hour spacewalk to install a new 1,700-pound ammonia coolant tank in the International Space Station's solar power truss. A depleted tank, removed during a spacewalk Tuesday, will be mounted in the shuttle Discovery's cargo bay for return to Earth.

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Flight Day 7 has commenced for the astronauts. This day will be devoted the mission's second spacewalk. Danny Olivas and Christer Fuglesang will venture outside around 5 p.m. to install the new ammonia coolant tank into the space station's Port 1 truss and stow the old tank in the shuttle bay.

Read our earlier status center coverage.