The astronauts spent a busy first few hours in orbit getting their spacecraft configured for the mission. They began setting up the onboard computer network, downlinking imagery, as well as powering up the shuttle's 50-foot-long robot arm for a post-launch checkout in preparation for its use in tomorrow's heat shield inspections. The crew got out of their launch and entry spacesuits, stowed away the mission specialists' seats and got some dinner as well. An eight-hour sleep period started at 6:29 a.m. EDT.

Astronaut Christer Fuglesang has downlinked the digital still imagery collected by the umbilical well cameras of the external tank after separation. The pictures will be analyzed to gauge how well the tank's foam insulation performed during the launch.

Initial checkout of the space shuttle robotic arm has been accomplished, mission specialist Pat Forrester reports.

Running four days late, the shuttle Discovery roared to life and shot into space late Friday, lighting up the night sky with a rush of fire as it set off on a 13-day mission to deliver 7.5 tons of supplies and equipment to the International Space Station.

Read our full story.

Space shuttle Discovery and crew have completed a 58-second engine firing to adjust the orbital path to the International Space Station. The course correction maneuver changed the shuttle's velocity by 90 feet per second.

CAPCOM astronaut Eric Boe in Mission Control just told the crew that no debris events were noted in the quick-look review of launch video.

Go for on-orbit operations! That's the formal call from Mission Control indicating the shuttle is in good shape following launch and the Discovery crew can proceed with mission activities.

Over the next few hours, the astronauts will busily begin setting up the onboard computer network, downlinking imagery and data gathered during ascent, as well as powering up the shuttle's 50-foot-long robot arm for a post-launch checkout in preparation for its use in tomorrow's heat shield inspections. The crew will be getting out of their launch and entry spacesuits, stowing away the mission specialists' seats and getting some dinner as well. An eight-hour sleep period begins at 6:29 a.m. EDT.

Both 60-foot-long payload bay doors of shuttle Discovery have been opened.

The crew's next big task will be opening up the payload bay doors and deploying the Ku-band communications antenna.

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

T+plus 40 minutes, 17 seconds. The twin Orbital Maneuvering System engines on the tail of Discovery have been fired successfully to propel the shuttle the rest of the way to orbit.

T+plus 39 minutes, 11 seconds. Ignition of the OMS engines.

T+plus 36 minutes. Discovery in the proper orientation for the upcoming 62-second maneuvering burn to raise the orbit. It will change the shuttle's speed by 95 feet per second.

T+plus 31 minutes, 30 seconds. The umbilical doors are closed and latched.

T+plus 30 minutes. The two flapper doors on the belly of Discovery are being swung closed to shield the umbilicals that had connected to the external fuel tank.

T+plus 27 minutes, 30 seconds. Pilot Kevin Ford has powered down the main propulsion system.

T+plus 16 minutes. The three Auxiliary Power Units are being shut down as planned.

T+plus 9 minutes, 35 seconds. It was a nominal MECO. A quick boost from the Orbital Maneuvering System engines is not required to reach the planned preliminary sub-orbital trajectory.

T+plus 9 minutes, 15 seconds. Still cameras embedded in Discovery's umbilical well are taking images of the external tank to document its foam. Flashes are illuminating the tank following this nighttime ascent.

T+plus 8 minutes, 48 seconds. The emptied external tank has been jettisoned from the belly of space shuttle Discovery. The tank will fall back into the atmosphere where it will burn up harmlessly.

T+plus 8 minutes, 31 seconds. MECO. Main Engine Cutoff confirmed! Shuttle Discovery is in orbit for its 37th mission, some 25 years after its maiden space voyage.

T+plus 7 minutes, 55 seconds. Discovery is 700 miles downrange.

T+plus 7 minutes, 40 seconds. The main engines are beginning to throttle down to ensure the shuttle does not experience forces greater than 3 g's as it continues to accelerate prior to engine shutdown.

T+plus 7 minutes, 2 seconds. Single engine press 104. The shuttle can reach orbit on the power from a single main engine should two fail at this point. But all three continue to fire properly.

T+plus 6 minutes, 45 seconds. Discovery is 466 miles downrange from the launch pad.

T+plus 6 minutes, 25 seconds. "Press to MECO." Discovery can now achieve a safe orbit on two engines. All three remain in good shape.

T+plus 6 minutes, 5 seconds. The shuttle has started rolling to a heads-up position to improve communications with the TDRS satellite network.

T+plus 5 minutes, 17 seconds. "Press to ATO". Discovery can reach an orbit, albeit a low orbit, on two engines should one shut down now. But all three powerplants are still running just fine.

T+plus 4 minutes, 51 seconds. Discovery is 212 miles downrange from the launch pad.

T+plus 4 minutes, 30 seconds. Discovery will be tripling its speed in the next four minutes to reach orbital velocity of 17,500 mph.

T+plus 4 minutes, 19 seconds. Discovery is 61 miles in altitude, 163 miles downrange from the launch pad.

T+plus 4 minutes. Negative return. The shuttle has passed the point where Discovery could turn around and make an emergency landing at Kennedy Space Center in the event of a main engine problem. Landing sites in France and Spain are now available to Discovery in the unlikely event an abort occurs during the remainder of today's launch.

T+plus 3 minutes, 20 seconds. The Orbital Maneuvering System engines have ignited for an extra kick.

T+plus 3 minutes. Overseeing today's climb to orbit from the Mission Control Center in Houston will be ascent flight director Richard Jones. Seated alongside in Houston in direct radio contact with the shuttle crew will be CAPCOM astronaut Eric Boe.

T+plus 2 minutes, 53 seconds. Commander Rick Sturckow just received the "Two-engine Moron" call from CAPCOM Eric Boe in Mission Control. The call means Discovery can now reach a Transatlantic Abort Landing site if one main engine fails. However, all three engines continue to burn normally.

T+plus 2 minutes, 40 seconds. Discovery is 37 miles in altitude, 54 miles downrange from the launch pad.

T+plus 2 minutes, 20 seconds. Guidance is converging as programmed. Discovery's engine nozzles are swiveling to steer the ship toward a precise point for main engine cutoff about six minutes from now.

T+plus 2 minutes, 10 seconds. Mission Control confirms a good jettison of the solid rocket boosters has occurred. The spent boosters will parachute into the Atlantic Ocean for retrieval. Discovery continues its streak toward space on the power generated by the three liquid-fueled main engines.

T+plus 90 seconds. The space shuttle now weighs just half of what it did at liftoff. The solid rocket boosters are burning 11,000 pounds of propellant every second. The main engines are guzzling a half-ton of liquid fuel per second from the external tank.

T+plus 70 seconds. Discovery's three main engines have revved back up to their 104 percent power setting. And Mission Control has given the "go at throttle up" call.

T+plus 60 seconds. Trailing a fiery plume 700 feet long and 400 feet wide, shuttle Discovery is streaking toward space for its mission to outfit the International Space Station with new scientific experiment hardware and living accommodations for the resident crews.

T+plus 35 seconds. Discovery's three liquid-fueled main engines are throttling down to their 72 percent power setting to ease the strain on the vehicle during passage through the region of maximum aerodynamic stresses.

T+plus 15 seconds. Discovery is rolling on course and lighting up the sky on this dazzling nighttime ascent to the catch the space station for rendezvous and docking Sunday night.

T-minus 10 seconds, go for ignition of the space shuttle main engines, 5, 4, 3, 2, 1 and LIFTOFF! Liftoff of Discovery, celebrating its 25 years of spaceflight with a new mission to shuttle up equipment and research gear to the International Space Station.

T-minus 31 seconds. AUTO SEQUENCE START! The handoff has occurred from the Ground Launch Sequencer to the space shuttle. Discovery's computers now controlling.

In the next few seconds, the solid rocket booster hydraulic steering system will be started, the orbiter's body flap and speed brake moved to their launch positions, the firing chain armed. Main engine ignition begins at T-minus 6.6 seconds.

T-minus 1 minute. Computers are verifying that the main engines are ready for ignition. Sound suppression water system is armed. The system will activate at T-minus 16 seconds to suppress the sound produced at launch. And the residual hydrogen burn ignitors are armed. They will be fired at T-minus 10 seconds to burn off hydrogen gas from beneath the main engine nozzles.

Shortly, the external tank strut heaters will be turned off; Discovery will transition to internal power; the liquid oxygen and liquid hydrogen outboard fill and drain valves will be closed; the payload bay vent doors will be positioned for the launch; and the gaseous oxygen vent arm will be verified fully retracted.

Now 90 seconds from launch of Discovery on its silver anniversary mission.

T-minus 2 minutes. The astronauts are being instructed to close and lock the visors on their launch and entry helmets.

At T-minus 1 minute, 57 seconds the replenishment to the flight load of liquid hydrogen in the external tank will be terminated and tank pressurization will begin.

T-minus 2 minutes, 30 seconds. The external tank liquid oxygen vent valve has been closed and pressurization of the LOX tank has started.

Discovery's power-producing fuel cells are transferring to internal reactants. The units will begin providing all electricity for the mission beginning at T-50 seconds.

And pilot Kevin Ford has been asked to clear the caution and warning memory system aboard Discovery. He will verify no unexpected errors in the system.

In the next few seconds, the gaseous oxygen vent hood will be removed from atop the external tank. Verification that the swing arm is fully retracted will be made by the ground launch sequencer at the T-minus 37 second mark.

T-minus 3 minutes. Orbiter steering check is now complete and the main engine nozzles are in their start positions.

T-minus 3 minutes, 30 seconds. The main engine nozzles now being moved through a computer controlled test pattern to demonstrate their readiness to support guidance control during launch.

T-minus 4 minutes. Activation of the APUs is complete. The three units are up and running normally.

And the final helium purge sequence is underway in the main propulsion system. This procedure readies fuel system valves for engine start. In the next few seconds, the aerosurfaces of Discovery will be run through a pre-planned mobility test to ensure readiness for launch. This is also a dress rehearsal for flight of the orbiter's hydraulic systems.

T-minus 5 minutes. The "go" has been given for for Auxiliary Power Unit start. Pilot Kevin Ford is now flipping three switches in Discovery's cockpit to start each of the three APU's. The units, located in the aft compartment of Discovery, provide the pressure needed to power the hydraulic systems of the shuttle. The units will be used during the launch and landing phases of the mission for such events as moving the orbiter's aerosurfaces, gimbaling the main engine nozzles and deploying the landing gear.

Over the course of the next minute, the orbiter's heaters will be configured for launch by commander Rick Sturckow, the fuel valve heaters on the main engines will be turned off in preparation for engine ignition at T-6.6 seconds and the external tank and solid rocket booster safe and arm devices will be armed.

T-minus 5 minutes, 30 seconds. APU pre-start is complete and the units are ready for activation. The orbiters flight data recorders have gone into the record mode to collect measurements of shuttle systems performance during flight.

T-minus 6 minutes. Pilot Kevin Ford has been asked by the orbiter test conductor to pre-start the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation after the countdown passes T-minus 5 minutes.

T-minus 7 minutes, 30 seconds. The Ground Launch Sequencer has started pulling the orbiter access arm away from the crew hatch on the port side of the vehicle. The arm was the passage way for the astronauts to board Discovery a few hours ago. The arm can be re-extended very quickly should the need arise later in the countdown.

T-minus 8 minutes and counting. Pilot Kevin Ford has flipped the switches in the cockpit of Discovery to directly connect the three onboard fuel cells with the essential power buses. Also, the stored program commands have been issued to the orbiter for antenna alignment and management during launch.

T-minus 9 minutes and counting! The Ground Launch Sequencer has been initiated. The computer program is located in a console in the Firing Room of the Complex 39 Launch Control Center. The GLS is the master of events through liftoff. During the last 9 minutes of the countdown, the computer will monitor as many as a thousand different systems and measurements to ensure that they do not fall out of any pre-determine red-line limits. At T-minus 31 seconds, the GLS will hand off to the onboard computers of Discovery to complete their own automatic sequence of events through the final half minute of the countdown.

Now 10 minutes from blastoff.

The countdown will resume from the T-minus 9 minute mark at 11:49:37 p.m. EDT.

NASA launch director Pete Nickolenko has conducted his poll and given approval to resume the countdown for liftoff at 11:59 p.m. EDT!

The poll by NASA test director Charlie Blackwell-Thompson confirms there are no technical issues or constraints standing in the way of launch at 11:59 p.m. EDT. The Range also reports "go" on the local weather. And Mission Control says that weather at abort landing sites is acceptable, too.

Ten minutes are remaining in this built-in hold. Final readiness polls will be conducted over the next few minutes.

Now 20 minutes from Discovery's launch on an eight-and-a-half minute trek to space. At main engine cutoff, Discovery will be flying on a suborbital trajectory with a high point of 136 statute miles and low point of 36 statute miles, inclined 51.6 degrees to the equator. A half-hour later, the twin orbital maneuvering engines will be fired to place the shuttle into a 142 by 121 statute mile orbit.

Powering space shuttle Discovery throughout its eight-and-a-half minute climb to orbit will be the three main engines built by Pratt & Whitney Rocketdyne. The cryogenic powerplants are fed with liquid hydrogen and liquid oxygen stored in the external fuel tank.

In the engine No. 1 position today is the Block 2-2052 engine now making its eighth launch. It has accumulated 4,613 seconds of total firing time on the previous missions, plus ground testing. STS-99 was its debut flight.

Making its ninth launch is the Block 2-2051 in the engine No. 2 position. This powerplant has 5,132 seconds of firing time including ground tests and launches starting with STS-96.

And Block 2-2047 is engine No. 3 on Discovery. It has 12 previous flights, starting with STS-91, and some 6,650 seconds of firing time.

The current observed and forecast weather for launch time remain "go" for tonight's flight of space shuttle Discovery.

The reusable solid rocket boosters, built by ATK, provide the primary thrust to propel the space shuttle away from Earth during the initial two minutes of flight. The 11 sections on each booster flying on Discovery are refurbished hardware. The upper cylinder on the left-hand booster, for example, flew on STS-5 in 1982. In all, the twin boosters flying this morning have reused segments and pieces that trace back to 64 previous shuttle launches and 20 ground test-firings.

The boosters will parachute into the Atlantic Ocean where a pair of retrieval ships are standing by to recover the rockets and tow them back to shore, beginning again the process to disassemble, refurbish and reuse the hardware in the future.

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At launch, the space station will be flying 225 miles above the Indian Ocean southwest of Tasmania. Liftoff at 11:59 p.m. EDT is timed to place Discovery on course to dock with the station Sunday night.

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 45-minute, 37-second built-in hold. Launch is targeted for 11:59:37 p.m. EDT. Today's available window to get the shuttle off the ground extends just five minutes to 12:04:29 a.m. EDT.

The Spaceflight Meteorology Group based in Houston, which is the group that handles weather at the shuttle landing sites, confirms conditions are observed and forecast "go" at the Kennedy Space Center for Return to Launch Site (RTLS).

The Main Propulsion System helium system is being reconfigured by pilot Kevin Ford. Soon the gaseous nitrogen purge to the aft skirts of the solid rocket boosters will be started.

Now one hour away from launch. All systems are working properly and the current weather is within limits.

Mission Control in Houston is loading Discovery's onboard computers with the proper guidance parameters based on the projected launch time.

Pilot Kevin Ford is configuring the displays inside Discovery's cockpit for launch while commander Rick Sturckow enables the abort steering instrumentation.

T-minus 20 minutes and counting. The countdown has resumed after a 10-minute hold. Clocks will tick down for the next 11 minutes to T-minus 9 minutes where the final planned hold is scheduled to occur. The hold length will be adjusted to synch up with today's preferred launch time of 11:59:37 p.m.

Discovery's onboard computers are now transitioning to the Major Mode-101 program, the primary ascent software. Also, engineers are dumping the Primary Avionics Software System (PASS) onboard computers. The data that is dumped from each of PASS computers is compared to verify that the proper software is loaded aboard for launch.

The Orbiter Closeout Crew is driving away from the pad.

The odds of acceptable weather at the planned launch time have increased to 80 percent. The radar is looking good right now.

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch is scheduled for 11:59:37 p.m. EDT, weather permitting.

During this built-in hold, all computer programs in Firing Room 4 of the Complex 39 Launch Control Center will be verified to ensure that the proper programs are available for the countdown; the landing convoy status will be verified and the landing sites will be checked to support an abort landing during launch today; the Inertial Measurement Unit preflight alignment will be verified completed; and preparations are made to transition the orbiter onboard computers to Major Mode 101 upon coming out of the hold. This configures the computer memory to a terminal countdown configuration.

The work to seal the shuttle's crew compartment hatch for flight is complete. And the closeout team that assisted the astronauts into Discovery this evening is stowing equipment in the White Room before leaving the launch pad now.

Commander Rick Sturckow is pressurizing the gaseous nitrogen system for Discovery's Orbital Maneuvering System engines and pilot Kevin Ford activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

At the current time, the launch weather rules are green across the board and the weather officer is cautiously optimistic.

The ground pyrotechnic initiator controllers (PICs) are scheduled to be powered up around this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.

The shuttle's two Master Events Controllers are being tested. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

The mainline computer program for the Ground Launch Sequencer has been activated.

The targeted liftoff time is 11:59:37 p.m. EDT. That's the moment when Earth's rotation carries the launch pad into the plane of the station's orbit.

The official window for extends from 11:54:44 to 12:04:29 a.m. EDT. Launching within that 10 minute period will enable Discovery to dock with the International Space Station on Sunday night.

A weather briefing is underway for senior launch officials and the odds remain at 60 percent for conditions being acceptable at launch time due to a chance of thunderstorms and anvil clouds in the area.

The outlook includes a few clouds at 3,000 feet, scattered clouds at 10,000 feet and broken clouds at 25,000 feet, 7 miles of visibility, southerly winds of 5 peaking to 10 knots, a temperature of 79 degrees F.

If the launch should slip into the weekend, there's a 70 percent chance of good weather on Saturday night and 80 percent on Sunday.

Just two hours remain until launch. The storm cells that has popped up around the Cape are dissipating, but weather remains the primary worry for the 11:59 p.m. EDT liftoff time.

Discovery's hatch has been closed and locked.

The orbiter closeout team at the launch pad is shutting Discovery's crew module hatch for flight.

The pad crew is ready to close up Discovery's hatch.

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T-minus 90 minutes and counting. Countdown clocks continue to tick down to T-minus 20 minutes where the next hold is planned. Activities remain on track for liftoff at 11:59 p.m., weather permitting.

The astronauts are completing a series of radio communication checks with ground controllers.

Initialization of the Ground Launch Sequencer has been completed. This is the master computer program that will run the final nine minutes of the countdown.

The final Discovery astronaut has boarded the shuttle today. Jose Hernandez, mission specialist No. 2 and flight engineer, has now entered the hatch. He will sit in the flight deck center seat, giving an extra set of eyes to aid the commander and pilot watch displays and switches during launch and landing.

The 47-year-old, born in Stockton, California, is the son of a Mexican migrant family who worked to harvest fruits and vegetables. He earned degrees in electrical engineering and worked at Lawrence Livermore National Laboratory and Johnson Space Center before becoming an astronaut. This will be his first spaceflight.

Read his biography here.

European Space Agency astronaut Christer Fuglesang, a particle physicist and avid sailor with one previous shuttle flight to his credit, is taking the center seat on the middeck for ascent. He'll be a spacewalker on this flight as mission specialist No. 4. The 52-year-old is a native of Stockholm, Sweden.

Read his biography here.

A weather cell has developed to the northwest as well. After clearing up nicely, the weather situation is trending in the wrong direction right now.

Retired Army colonel and helicopter pilot Pat Forrester has boarded the space shuttle tonight to be seated in the flight deck's aft-right seat and serve as mission specialist No. 1. He grew up in Springfield, Virginia, attended West Point and has flown in space twice before.

Read his biography here.

Three hours and counting until liftoff time. No significant technical issues are being worked in the countdown, but the weather continues to be watched. Some storms have developed to the west, southwest and south.

Danny Olivas, raised in El Paso, Texas, is mission specialist No. 3 and the lead spacewalker for the flight. The 43-year-old mechanical engineer was working at NASA's Jet Propulsion Laboratory when selected as an astronaut.

He will ride into orbit in the middeck's left seat.

Read his biography here.

Kevin Ford, a 49-year-old retired Air Force colonel from Montpelier, Indiana, will be Discovery's pilot. He was an F-15 pilot and an F-16 test pilot.

This spaceflight rookie is making his way to the flight deck's front-right seat right now.

Read Ford's biography here.

Nicole Stott, the station-bound astronaut set to join the Expedition 20 crew living aboard the outpost, serves as Discovery's mission specialist No. 5 for the launch. The 46-year-old from Clearwater, Florida attended Embry-Riddle Aeronautical University before going to work as a structural design engineer at Pratt & Whitney. She then became a Kennedy Space Center worker on space shuttles and station hardware.

Once at the space station, she will exchange places with astronaut Tim Kopra, who then will return to Earth on the shuttle to conclude a month-and-a-half in space.

Stott just crawled through Discovery's hatch to take the right-hand seat on the middeck.

Read her biography here.

Shuttle commander Rick Sturckow, a 48-year-old Marine colonel who grew up on a ranch outside of San Diego, California, leads this voyage of Discovery. It will be his fourth spaceflight to the International Space Station, having been a pilot on STS-88 and -105 and commander on STS-117.

He is the first astronaut to board the shuttle this evening, taking the forward-left seat on the flight deck.

Read Sturckow's biography here.

Discovery's crew has arrived at launch pad 39A. The AstroVan came to a stop on the pad surface near the Fixed Service Structure tower elevator that will take the seven-man crew to the 195-foot level to begin boarding the shuttle.

The AstroVan is passing the 52-story Vehicle Assembly Building where Discovery was attached to its external tank and solid rocket boosters and the adjacent Launch Control Center.

The Press Site is located across the street, and reporters went outside to watch the passing convoy. This is a launch day tradition to say farewell and good luck to the astronaut crews.

The crew of commander Rick Sturckow, pilot Kevin Ford, mission specialists Pat Forrester, Jose Hernandez, Danny Olivas, Christer Fuglesang and station-bound astronaut Nicole Stott just emerged from their quarters to board the AstroVan for the ride from the Kennedy Space Center Industrial Area to launch pad 39A on the edge of the Atlantic Ocean.

Here come the astronauts down the hallway from the suitup room.

All of the launch weather rules are now green and go! Anvil clouds from storms located south of the Cape will be the lingering concern this evening.

T-minus 3 hours and counting. The countdown clocks are ticking again after the planned two-and-a-half hour built-in hold. Clocks will proceed to T-minus 20 minutes when the next hold is scheduled. A final hold occurs at the T-minus 9 minute mark to synch up with the 11:59 p.m. EDT launch time.

A gorgeous sunset here in Florida as everything continues to go smoothly in the countdown for launch at 11:59 p.m. EDT. There remains optimism that the weather will be cooperative as clocks tick closer to liftoff time.

Here's a photo taken from outside the Spaceflight Now office at Kennedy Space Center showing a bit of rainbow over the launch pad.

The lightning, debris clouds and cloud ceiling rules aren't being violated any longer.

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The astronauts are donning their day-glow orange launch and entry partial pressure spacesuits. After final adjustments and pressure checks, the astronauts will depart the suitup room and take the elevator down to the ground level of the Operations and Checkout Building to board the AstroVan for the trip to launch pad 39A around 8:09 p.m.

The lightning warning at the launch pad has been discontinued.

It's now raining at launch pad 39A. The weather rule board shows criteria for lightning, field mills, anvil, cumulus and debris clouds, ceiling and flight thru precipitation are red. But the hope is the weather will pass through now and clear out by launch time in a few hours. Some dry air from the west is expected later tonight.

Our launch webcast anchored by Miles O'Brien, with David Waters and special guests is streaming live on the right-hand side of our page.

Three lightning strikes have been detected at 3 miles, 4.4 miles and 4.8 miles from the launch pad.

A Phase 2 lightning warning has been issued, so the Final Inspection Team is limited on where it can go on the pad right now.

The Final Inspection Team is out at the launch pad to scan the vehicle for any ice or debris concerns following fueling operations. The team is responsible for checking the shuttle and launch pad one last time prior to liftoff.

The team is comprised of engineers and safety officials from NASA, United Space Alliance and tank-builder Lockheed Martin. At the conclusion of their two-hour tour-of-duty, the team will have walked up and down the entire fixed service structure and mobile launcher platform.

The team is on the lookout for any abnormal ice or frost build-up on the vehicle and integrity of the external tank foam insulation.

The team uses a portable infrared scanner that gathers temperature measurements on the surface area of the shuttle and can spot leaks. The scanner will be used to obtain temperature data on the external tank, solid rocket boosters, space shuttle orbiter, main engines and launch pad structures. The scanner can also spot leaks of the cryogenic propellants, and due to its ability to detect distinct temperature differences, can spot any dangerous hydrogen fuel that is burning. The team member also is responsible for photo documentation.

The team wears the highly visible day-glow orange coveralls that are anti-static and flame resistant. Each member also has a self-contained emergency breathing unit that holds about 10 minutes of air.

Launch weather officer Kathy Winters is giving managers some optimism that conditions will clear out as the evening wears on. The lightning rule isn't being violated any longer.

A fifth weather rule has gone red. This one is the criteria to guard against flight through precipitation.

A light sprinkle falling here at the Press Site now.

Several of the launch weather rules are being violated at this hour due to some storm cells west of the launch pad, including the criteria for anvil and cumulus clouds, lightning and the field mills that measure the electrical potential.

With the hazardous tanking operation now completed, the Orbiter Closeout Crew and Final Inspection Team have arrived at the pad to perform their jobs. The closeout crew will ready Discovery's crew module for the astronauts' ingress in a couple of hours; and the inspection team will give the entire vehicle a check for any ice formation following fueling.

A current check of the launch weather rules shows the anvil cloud rule is "red" as some weather moves through the local area.

TANK FULL. Liquid oxygen has entered stable replenishment mode, officially completing today's three-hour external tank filling process at 5:48 p.m. EDT.

Astronaut Jose Hernandez just tweeted on his Twitter page: "Hopefully this is my last tweet before I go into space! So far all systems are go. We'll have lunch then get ready to suit up!"

T-minus 3 hours and holding. Clocks have entered a planned two-hour, 30 minute built-in hold. Additional pauses are scheduled at the T-minus 20 and T-minus 9 minute marks, setting up the countdown for launch at 11:59 p.m. EDT.

Liquid hydrogen loading to 100 percent was completed at 5:24 p.m. The tank will be in a stable replenishment through the rest of the countdown to replace the supercold propellant that naturally boils away.

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Looking ahead to tonight's 11:59 p.m. EDT launch time, the weather forecast continues to predict a 60 percent chance of acceptable conditions due to possible problems with clouds, rain and storms.

The liquid hydrogen tank has reached the 98 percent level, completing the fast-fill mode and beginning the topping sequence.

Now passing the two-hour mark into this afternoon's fueling operations. No troubles have been reported by the launch team during tanking.

The cryogenics flow from storage spheres at the pad, through feed lines to the mobile launcher platform, into Discovery's aft compartment and finally into the external fuel tank.

The inboard liquid hydrogen fill and drain valve that caused the earlier scrub is working normally today, NASA says. A spokesman says there has been no repeat of the valve positioning problem experienced on Tuesday.

The latest high definition video of the STS-128 launch preparations is available to Spaceflight Now+Plus customers. A full listing of video can be seen here.

Standard definition clips are posted our video archive.

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No technical issues are being reported in the countdown as fueling continues for tonight's 11:59 p.m. EDT launch of Discovery.

Loading of both liquid hydrogen and liquid oxygen have switched to the "fast-fill" mode as fueling of space shuttle Discovery proceeds via remote control at launch pad 39A.

There are two tanks inside the shuttle's external fuel tank. The liquid oxygen tank occupies the top third of the bullet-shaped tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit. The liquid hydrogen tank is contained in the bottom two-thirds of the external tank. It holds 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit.

The low-level sensors in the external tank have now reading "wet" as they get submerged by the cryogenics.

Liquid oxygen loading has completed chilldown and started the slow-fill at 3:22 p.m. EDT.

The liquid hydrogen loading transitioned from chilldown to the "slow-fill" mode at 2:54 p.m. This fills a small fraction of the tank, then the loading switches to "fast-fill" mode.

After brief weather delay, today's filling of space shuttle Discovery's external fuel tank started at 2:45 p.m. with the chilldown thermal conditioning process. This will be followed by the slow-fill mode and then the fast-fill mode to load the tank over the next three hours.

NASA's Mission Management Team cleared the shuttle Discovery for a fourth launch try Friday night, approving a waiver to pre-launch flight rules allowing engineers to cycle a liquid hydrogen valve, if necessary, to confirm it is closed.

Read our full story.

The latest revision to the weather forecast for the first hour of fueling now calls for only a 20 percent chance of lightning within 5 miles of the pad. It was 30 percent earlier.

The outlook includes scattered low- and mid-level clouds, broken high clouds, easterly winds of 5 to 10 knots, isolated thunderstorms and a temperature of 87 degrees F.

The countdown clocks have picked up after the T-minus 6 hour hold point. The next built-in hold will occur at T-minus 3 hours.

The launch team is awaiting a "go" weather forecast before the start of fueling.

The start time for fueling will be dependent on the weather. There is a chance of stormy weather this afternoon. The odds of lightning has to be less than 20 percent for fueling operation to begin.

Go for launch! The official approval to press ahead has been given.

The Mission Management Team meeting has blessed the flight rationale and workaround procedures after reviewing test data on the the inboard liquid hydrogen fill and drain valve.

A formal decision on moving forward with another launch attempt and re-fueling of shuttle Discovery should be made shortly. Tanking is slated to begin at 2:34 p.m. EDT.

Discovery's seven astronauts are being awakened for launch day at this time. They'll have breakfast at 2 p.m. and then undergo final medical exams at 2:30 p.m. Suit up begins around 7:30 p.m. and departure from crew quarters is scheduled for 8:09 p.m. in preparation for blastoff at 11:59 p.m. EDT.

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No official word out of the meeting as yet, a NASA spokesperson says.

We have posted the latest ascent and flight plan charts to help readers follow along with the voyage of Discovery.

The gantry was retracted at sunrise this morning and the countdown resumed ticking at 8:34 a.m. EDT from the T-minus 11 hour mark, a point to which clocks were recycled following yesterday's last scrub.

Today's Mission Management Team meeting to review the analysis work and flight rationale concerning the fill and drain valve begins at 12 p.m.

The count will enter the planned T-minus 6 hour hold at 1:34 p.m. EDT to await a "go" for fueling. Loading of Discovery's external fuel tank would start at 2:34 p.m. EDT, if all systems are deemed ready.

The official launch window, based on the latest radar tracking of the space station's orbit and subsequent revision from Mission Control, extends from 11:54:37 p.m. to 12:04:37 a.m. EDT. The targeted liftoff time occurs inside the window at 11:59:37 p.m. EDT. That's the moment when Earth's rotation carries the launch pad into the plane of the station's orbit for a Flight Day 3 rendezvous.

Forecasters at the 45th Weather Squadron project 60 percent odds that conditions will be within limits for both fueling and launching Discovery on Friday afternoon and evening, respectively.

"The Bermuda High ridge axis is currently located north of the Kennedy Space Center area. In this regime, early morning coastal showers are typical and afternoon thunderstorms form to the west and remain inland. An upper level trough will deepen into the Gulf of Mexico by launch day, and the weather pattern will shift from easterly flow to southwesterly flow during the day Friday. With this unstable atmosphere, isolated thunderstorms can develop in the area into the evening, and anvils from storms may linger into the launch time," the Air Force weather team says.

"Also, Tropical Storm Danny is forecast to move north of Florida by Friday mid-morning causing high seas in the solid rocket booster recovery area.

"Our primary concerns for launch are anvils within 10 nautical miles of the launch pad and thunderstorms within 20 nautical miles of the Shuttle Landing Facility, plus high seas in the SRB recovery area.

"If we delay 24 hours, the surface flow becomes solidly southwest. Afternoon sea breeze storms will form and remain along the east coast, causing a 60 percent chance of violating tanking weather constraints."

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

Read our earlier status center coverage.