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Orbiter: Atlantis
Mission: STS-135
Payload: Raffaello
Launch: July 8, 2011
Time: 11:29 a.m. EDT
Site: Pad 39A, Kennedy Space Center
Landing: July 21 @ approx. 5:57 a.m. EDT
Site: KSC's Shuttle Landing Facility
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Cdr Chris Ferguson

Pilot Doug Hurley

MS 1 Sandy Magnus

MS 2 Rex Walheim




Mission Status Center

By Justin Ray

Live coverage of space shuttle Atlantis' STS-135 mission to the International Space Station. Text updates will appear automatically; there is no need to reload the page. Follow us on Twitter.

FRIDAY, JULY 8, 2011
Flight controllers in Houston have bid goodnight to commander Chris Ferguson and crew. After successfully getting into orbit, the astronauts quickly went to work transforming their rocket into a spacecraft by opening the payload bay doors and activating the myriad of systems. They've already completed the first in the series of trajectory maneuvers en route to the space station. The shuttle's robotic arm also got checked out to prepare for tomorrow's post-launch heat shield inspections.

The astronauts heading to bed for an eight-hour sleep period. They'll be awakened for Flight Day 2 at 3:59 a.m. EDT.
2322 GMT (7:22 p.m. EDT)
The astronauts have examined Atlantis' windows and reported to Mission Control there's no launch-related clouding or damage.
2259 GMT (6:59 p.m. EDT)
The crew has completed the robotics checkout with no problems to report.
2230 GMT (6:30 p.m. EDT)
After a cliff-hangar countdown, the space shuttle Atlantis thundered to life and majestically rocketed into history Friday, putting on one last sky show for spectators jamming area roads and beaches to witness NASA's 135th and final shuttle launch.

Read our full story.
2203 GMT (6:03 p.m. EDT)
The astronauts have powered up and extended space shuttle Atlantis' robotic arm for a system checkout in preparation for tomorrow's use in the heat shield inspection process.
2015 GMT (4:15 p.m. EDT)
The latest version of the NASA Television schedule (Rev. A) can be downloaded here.
1950 GMT (3:50 p.m. EDT)
Statement by President Obama on today's launch:

Today, Americans across the country watched with pride as four of our fellow citizens blasted off from the Kennedy Space Center in the Space Shuttle Atlantis, and America reached for the heavens once more.

Behind Atlantis and her crew of brave astronauts stand thousands of dedicated workers who have poured their hearts and souls into America's Space Shuttle program over the past three decades. To them and all of NASA's incredible workforce, I want to express my sincere gratitude. You helped our country lead the space age, and you continue to inspire us each day.

Today's launch may mark the final flight of the Space Shuttle, but it propels us into the next era of our never-ending adventure to push the very frontiers of exploration and discovery in space. We'll drive new advances in science and technology. We'll enhance knowledge, education, innovation, and economic growth. And I have tasked the men and women of NASA with an ambitious new mission: to break new boundaries in space exploration, ultimately sending Americans to Mars. I know they are up to the challenge – and I plan to be around to see it.

Congratulations to Atlantis, her astronauts, and the people of America's space program on a picture-perfect launch, and good luck on the rest of your mission to the International Space Station, and for a safe return home. I know the American people share my pride at what we have accomplished as a nation, and my excitement about the next chapter of our preeminence in space.
1920 GMT (3:20 p.m. EDT)
Space shuttle Atlantis and crew have completed NC1 engine firing to adjust the orbital path to the International Space Station. The 94-second course correction maneuver using both Orbital Maneuvering System engines changed the shuttle's velocity by 145 feet per second.
1845 GMT (2:25 p.m. EDT)
CAPCOM astronaut Butch Wilmore in Mission Control just told the crew that launch video and imagery continues to be analyzed but there's no concerns noted so far.
1712 GMT (1:12 p.m. EDT)
T+plus 103 minutes. Atlantis' antenna for Ku-band high-speed communications is being deployed. Standing by for system activation.
1710 GMT (1:10 p.m. EDT)
Check out our launch photo gallery taken from the Press Site.
1704 GMT (1:04 p.m. EDT)
T+plus 95 minutes. Go for orbit operations! That's the formal call from Mission Control indicating the shuttle is in good shape following launch and the Atlantis crew can proceed with mission activities.

Both 60-foot-long payload bay doors of shuttle Atlantis have been opened and the radiators activated.

Over the next few hours, the astronauts will busily begin setting up the onboard computer network and downlinking imagery and data gathered during ascent. The crew will be getting out of their launch and entry spacesuits, stowing away the mission specialists' seats and getting some dinner as well. And checkout of the shuttle's robot arm is planned. An eight-hour sleep period begins at 8 p.m. EDT.
1703 GMT (1:03 p.m. EDT)
T+plus 94 minutes. And now the port door has opened.
1701 GMT (1:01 p.m. EDT)
T+plus 92 minutes. The starboard door has swung open.
1644 GMT (12:44 p.m. EDT)
T+plus 75 minutes. Mission Control has voiced a "go" to the crew for payload bay door opening.
1630 GMT (12:30 p.m. EDT)
Share your thoughts about today's launch of the space shuttle Atlantis on our Facebook page!
1629 GMT (12:29 p.m. EDT)
T+plus 60 minutes. The crew continues working through its post-launch activities. The next big milestones will be opening up the payload bay doors and deploying the Ku-band communications antenna.
1616 GMT (12:16 p.m. EDT)
T+plus 47 minutes. The official liftoff time was 11:29:03.9 a.m. EDT.
1609 GMT (12:09 p.m. EDT)
T+plus 40 minutes. The burn has resulted in a 143 by 98 nautical mile orbit, Mission Control reports.
1608 GMT (12:08 p.m. EDT)
T+plus 39 minutes. The twin Orbital Maneuvering System engines on the tail of Atlantis have been fired successfully to propel the shuttle the rest of the way to orbit.
1607 GMT (12:07 p.m. EDT)
T+plus 37 minutes, 58 seconds. Ignition of the OMS engines has been confirmed.
1606 GMT (12:06 p.m. EDT)
T+plus 37 minutes. Atlantis in the proper orientation for the upcoming maneuvering burn to raise the orbit toward the International Space Station.
1602 GMT (12:02 p.m. EDT)
T+plus 33 minutes. Commander Chris Ferguson and pilot Doug Hurley are getting Atlantis maneuvered into the proper position for the OMS 2 engine burn to boost the shuttle from its current orbit of 140 by 36 mile statute miles.
1556 GMT (11:56 a.m. EDT)
T+plus 27 minutes. The two flapper doors on the belly of Atlantis are swinging closed to shield the umbilicals that had connected to the external fuel tank.
1554 GMT (11:54 a.m. EDT)
T+plus 25 minutes. The three Auxiliary Power Units have been shut down by pilot Doug Hurley. He also powered down the main propulsion system.
1544 GMT (11:44 a.m. EDT)
T+plus 15 minutes. The planned OMS 2 burn will begin at approximately T+plus 37 minutes.
1538 GMT (11:38 a.m. EDT)
T+plus 9 minutes, 30 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.
1538 GMT (11:38 a.m. EDT)
T+plus 9 minutes, 15 seconds. Still cameras embedded in Atlantis' umbilical well are taking images of the external tank to document its foam.
1537 GMT (11:37 a.m. EDT)
T+plus 8 minutes, 47 seconds. The emptied external tank has been jettisoned from the belly of space shuttle Atlantis. The tank will fall back into the atmosphere where it will burn up harmlessly.
1537 GMT (11:37 a.m. EDT)
T+plus 8 minutes, 30 seconds. MECO. Main Engine Cutoff confirmed! The space shuttle has completed its final powered flight to orbit.
1537 GMT (11:37 a.m. EDT)
T+plus 8 minutes. Atlantis is traveling at 15,000 mph.
1536 GMT (11:36 a.m. EDT)
T+plus 7 minutes, 45 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.
1536 GMT (11:36 a.m. EDT)
T+plus 7 minutes, 18 seconds. Atlantis is traveling at 12,000 mph.
1536 GMT (11:36 a.m. EDT)
T+plus 7 minutes, 5 seconds. Single engine press. 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.
1535 GMT (11:35 a.m. EDT)
T+plus 6 minutes, 28 seconds. "Press to MECO." Atlantis can now achieve a safe orbit on two engines. All three remain in good shape.
1535 GMT (11:35 a.m. EDT)
T+plus 6 minutes. The shuttle has started rolling to a heads-up position to improve communications with the TDRS satellite network.
1534 GMT (11:34 a.m. EDT)
T+plus 5 minutes, 40 seconds. Atlantis is 315 miles downrange from the launch pad, traveling over 7,700 mph.
1534 GMT (11:34 a.m. EDT)
T+plus 5 minutes, 12 seconds. "Press to ATO". Atlantis 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.
1533 GMT (11:33 a.m. EDT)
T+plus 4 minutes, 40 seconds. Atlantis will be tripling its speed in the next four minutes to reach orbital velocity of nearly 17,500 mph.
1533 GMT (11:33 a.m. EDT)
T+plus 4 minutes, 30 seconds. Atlantis is 62 miles in altitude, 200 miles downrange from the launch pad, traveling over 5,500 mph.
1533 GMT (11:33 a.m. EDT)
T+plus 4 minutes. Negative return. The shuttle has passed the point where Atlantis 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 Atlantis in the unlikely event an abort occurs during the remainder of today's launch.
1532 GMT (11:32 a.m. EDT)
T+plus 3 minutes, 40 seconds. Atlantis is 54 miles in altitude, 120 miles downrange from the launch pad, traveling at 4,200 mph.
1532 GMT (11:32 a.m. EDT)
T+plus 3 minutes, 30 seconds. Overseeing today's climb to orbit from the Mission Control Center is ascent flight director Richard Jones. Seated alongside in Houston in direct radio contact with the crew is CAPCOM astronaut Butch Wilmore.
1531 GMT (11:31 a.m. EDT)
T+plus 2 minutes, 35 seconds. The Orbital Maneuvering System engines have been ignited for an additional kick of thrust during Atlantis' climb uphill.
1531 GMT (11:31 a.m. EDT)
T+plus 2 minutes, 20 seconds. Guidance is converging as programmed. Atlantis' engine nozzles are swiveling to steer the ship toward a precise point for main engine cutoff about six minutes from now.
1531 GMT (11:31 a.m. EDT)
T+plus 2 minutes, 10 seconds. Jettison of the solid rocket boosters has occurred. The spent boosters will parachute into the Atlantic Ocean for retrieval. Atlantis continues its streak toward space on the power generated by the three liquid-fueled main engines.
1530 GMT (11:30 a.m. EDT)
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.
1530 GMT (11:30 a.m. EDT)
T+plus 70 seconds. Atlantis' three main engines have revved back up to their 104 percent power setting. And Mission Control has given the "go at throttle up" call.
1530 GMT (11:30 a.m. EDT)
T+plus 60 seconds. The Atlantis is flying heads-down, wings-level on a northeasterly trajectory away from the Florida spaceport on its last ascent to space.
1529 GMT (11:29 a.m. EDT)
T+plus 40 seconds. Atlantis' 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.
1529 GMT (11:29 a.m. EDT)
T+plus 20 seconds. Atlantis has rolled on course for rendezvous with the International Space Station.
1529 GMT (11:29 a.m. EDT)
T+plus 10 seconds. Houston is now controlling as the space shuttle ascends away from Complex 39 for its 135th mission.
1529 GMT (11:29 a.m. EDT)
T-minus 10, 9, 8, 7, 6, main engine ignition, 4, 3, 2, 1 and LIFTOFF! Liftoff of the final flight for America's space shuttle as Atlantis clears the tower.
1528:33 GMT (11:28:33 a.m. EDT)
T-minus 31 seconds. AUTO SEQUENCE START! The handoff has occurred from the Ground Launch Sequencer to the space shuttle. Atlantis' 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.
1527 GMT (11:27 a.m. EDT)
Today's window extends just over three minutes.
1527 GMT (11:27 a.m. EDT)
Arm is in fact retracted. Standing by to resume the count.
1526 GMT (11:26 a.m. EDT)
This hold was called due to concern that the gaseous oxygen vent arm wasn't fully retracted.
1526:15 GMT (11:26:15 a.m. EDT)
T-minus 31 seconds and holding! Ground Launch Sequencer has stopped the clock.
1525:46 GMT (11:25:46 a.m. EDT)
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; Atlantis 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.
1525:16 GMT (11:25:16 a.m. EDT)
Now 90 seconds from the final launch of the space shuttle.
1524:46 GMT (11:24:46 a.m. EDT)
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.
1524:16 GMT (11:24:16 a.m. EDT)
T-minus 2 minutes, 30 seconds. The external tank liquid oxygen vent valve has been closed and pressurization of the LOX tank has started.

Atlantis' 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 Doug Hurley has been asked to clear the caution and warning memory system aboard Atlantis. 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.
1523:46 GMT (11:23:46 a.m. EDT)
T-minus 3 minutes. Orbiter steering check is now complete and the main engine nozzles are in their start positions.
1523:16 GMT (11:23:16 a.m. EDT)
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.
1522:46 GMT (11:22:46 a.m. EDT)
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 Atlantis 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.
1521:46 GMT (11:21:46 a.m. EDT)
T-minus 5 minutes and counting. The "go" has been given for Auxiliary Power Unit start. Pilot Doug Hurley is now flipping three switches in Atlantis' cockpit to start each of the three APU's. The units, located in the aft compartment of Atlantis, 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 Chris Ferguson, 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.
1521:16 GMT (11:21:16 a.m. EDT)
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.
1520:46 GMT (11:20:46 a.m. EDT)
T-minus 6 minutes. Pilot Doug Hurley 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.
1520:16 GMT (11:20:16 a.m. EDT)
T-minus 6 minutes, 30 seconds and counting.
1519:16 GMT (11:19:16 a.m. EDT)
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 Atlantis a few hours ago. The arm can be re-extended very quickly should the need arise later in the countdown.
1518:46 GMT (11:18:46 a.m. EDT)
T-minus 8 minutes and counting. Pilot Doug Hurley has flipped the switches in the cockpit of Atlantis 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.
1517:46 GMT (11:17:46 a.m. EDT)
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 Atlantis to complete their own automatic sequence of events through the final half minute of the countdown.
1516:46 GMT (11:16:46 a.m. EDT)
Now 10 minutes from blastoff.
1516 GMT (11:16 a.m. EDT)
The forecast for emergency landing weather here is "no go" but the Mission Management Team is waiving that.
1515 GMT (11:15 a.m. EDT)
The countdown will resume from the T-minus 9 minute mark at 11:17:46 a.m. EDT.
1515 GMT (11:15 a.m. EDT)
Weather officially "go" for launch!
1514 GMT (11:14 a.m. EDT)
NASA launch director Mike Leinbach has conducted his poll and given provisional approval to resume the countdown for liftoff at 11:26 a.m. EDT. But still waiting on final official "go" on the weather.
1513 GMT (11:13 a.m. EDT)
The poll by NASA test director Jeff Spaulding confirms there are no technical issues or constraints standing in the way of launch at 11:26 a.m. EDT. The Range also reports "go" on the local weather. But Mission Control needs a few more minutes to look at weather for the abort landing site here at the Cape.
1506 GMT (11:06 a.m. EDT)
Powering space shuttle Atlantis 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 2-2047 engine now making its 14th launch. STS-91 was its debut flight on Endeavour to the Russian space station Mir and STS-132 was the most recent aboard Atlantis to the International Space Station.

Making its third launch is the Block 2-2060 in the engine No. 2 position. The previous flights included Endeavour's STS-127 and Discovery's STS-131 mission to the International Space Station.

And Block 2-2045 is engine No. 3 on Atlantis. This powerplant is flying for the 12th time starting with Endeavour's STS-89 to Mir and most recently on Discovery's STS-131.
1505 GMT (11:05 a.m. EDT)
An area of weather has popped up over northern Merritt Island that's being looked at very carefully.
1501 GMT (11:01 a.m. EDT)
We're now 25 minutes from Atlantis' launch on an eight-and-a-half minute trek to space. At main engine cutoff, Atlantis 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 98 statute mile orbit.
1455 GMT (10:55 a.m. EDT)
At launch, the space station will be flying 232 miles above the Pacific Ocean, east of Christchurch, New Zealand. Liftoff at 11:26 a.m. EDT is timed to place Atlantis on course to dock with the station two days from now.
1445 GMT (10:45 a.m. EDT)
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 Atlantis are a mixture of refurbished and brand new hardware. The upper cylinder on the left booster, for example, flew on the original shuttle mission in 1981 and now flies on the final one. The forward dome on the left-hand booster is flying for the very first time.

In all, Atlantis' twin boosters have reused segments and pieces that trace back to 59 previous shuttle launches and 12 ground test-firings.

Detailed history information about Atlantis' two boosters can be seen in this PDF download here.

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.
1438 GMT (10:38 a.m. EDT)
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1432 GMT (10:32 a.m. EDT)
T-minus 9 minutes and holding. Countdown clocks have gone into the planned 45-minute, 46-second built-in hold. Launch is targeted for 11:26:46 a.m. EDT.
1430 GMT (10:30 a.m. EDT)
The Main Propulsion System helium system has been reconfigured by pilot Doug Hurley. Soon the gaseous nitrogen purge to the aft skirts of the solid rocket boosters will be started.
1429 GMT (10:29 a.m. EDT)
Commander Chris Ferguson has enabled the abort steering instrumentation. And pilot Doug Hurley has configured the displays inside Atlantis' cockpit for launch.
1428 GMT (10:28 a.m. EDT)
Mission Control in Houston is loading Atlantis' onboard computers with the proper guidance parameters based on the projected launch time.
1426 GMT (10:26 a.m. EDT)
Now one hour away from liftoff. An area of clearing in the clouds is drifting this way.
1421 GMT (10:21 a.m. EDT)
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 11:26 a.m. EDT.

Atlantis' 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.
1419 GMT (10:19 a.m. EDT)
Weather is "go" now!
1415 GMT (10:15 a.m. EDT)
The official launch window based on radar tracking of the space station's orbit begins at 11:21:46 and extends until 11:31:19 a.m. EDT for Atlantis to rendezvous with the station on Flight Day 3.

The preferred launch time is 11:26:46 a.m. EDT.
1411 GMT (10:11 a.m. EDT)
T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch is scheduled for 11:26 a.m. EDT.

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.
1409 GMT (10:09 a.m. EDT)
The work to seal the shuttle's crew compartment hatch for flight is complete. And the closeout team that assisted the astronauts into Atlantis today has stowed equipment in the White Room before leaving the launch pad now.
1403 GMT (10:03 a.m. EDT)
Commander Chris Ferguson is pressurizing the gaseous nitrogen system for Atlantis' Orbital Maneuvering System engines and pilot Doug Hurley activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.
1354 GMT (9:54 a.m. EDT)
The latest weather briefing to the launch director continues to show a 70 percent of "no go" conditions at today's 11:26 a.m. EDT liftoff time. Weather remains "red" right now for thick clouds.
1352 GMT (9:52 a.m. EDT)
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.
1340 GMT (9:40 a.m. EDT)
Weather remains "no go" for thick clouds over the launch site.
1326 GMT (9:26 a.m. EDT)
Atlantis' hatch has been closed and locked.
1320 GMT (9:20 a.m. EDT)
The orbiter closeout team at the launch pad is shutting Atlantis' crew module hatch for flight.
1315 GMT (9:15 a.m. EDT)
The radar shows some rain within the restricted 20 mile zone around the shuttle's emergency runway here at Kennedy Space Center.
1300 GMT (9:00 a.m. EDT)
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1237 GMT (8:37 a.m. EDT)
The final Atlantis astronaut has boarded the shuttle today. Rex Walheim just entered the hatch to sit on the flight deck's aft-center seat as mission specialist No. 2 and flight engineer.

The 48-year-old California native, a retired Air Force colonel, has flown aboard shuttle Atlantis twice before. Walheim's first spaceflight in 2002 on the STS-110 mission installed the center section of the International Space Station's truss backbone. Then came STS-122 in 2008 that brought the European Space Agency's Columbus science laboratory to the station.

Read his NASA biography here and Spaceflight Now+Plus subscribers can watch an extended pre-launch interview.
1233 GMT (8:33 a.m. EDT)
Astronaut Sandy Magnus, a native of Belleville, Illinois, is ingressing the flight deck's aft-right seat as Atlantis' mission specialist No. 1 to launch aboard the space shuttle for the third time.

NASA selected Magnus, who has a doctorate in material science, as an astronaut in 1996 and she flew as a rookie aboard shuttle Atlantis' STS-112 mission in 2002 that installed the Starboard 1 truss on the International Space Station. Then came assignment as an Expedition 18 flight engineer and science officer aboard the station, launching with Ferguson aboard Endeavour's STS-126 and spending four-and-a-half months living on the outpost before returning to Earth on Discovery's STS-119 mission in 2009.

Read her NASA biography here and Spaceflight Now+Plus subscribers can watch an extended pre-launch interview.
1231 GMT (8:31 a.m. EDT)
Now passing the T-minus 2 hour mark in the countdown. A pair of built-in holds are planned at T-minus 20 minutes and T-minus 9 minutes, leading toward the 11:26 a.m. T-0 time.
1215 GMT (8:15 a.m. EDT)
Atlantis pilot Doug Hurley is making his way to the flight deck's front-right seat right now.

Born in Upstate New York, his interests in engineering and flying led Hurley on a path to becoming an astronaut. The 44-year-old colonel from the Marine Corps previously flew for 16 days aboard shuttle Endeavour's STS-127 mission in 2009 that delivered the final piece of Japan's scientific facilities at the International Space Station.

Read his NASA biography here and Spaceflight Now+Plus subscribers can watch an extended pre-launch interview.
1205 GMT (8:05 a.m. EDT)
Commander Chris Ferguson, a 49-year-old retired Navy captain born in Philadelphia, is the first astronaut to board the shuttle today, taking the forward-left seat on the flight deck.

This will be his third spaceflight after serving as pilot on Atlantis' STS-115 mission in 2006 that installed another solar power truss on the International Space Station and commander of Endeavour's STS-126 mission in 2008 that brought up critical equipment to remodel the outpost's interior in preparation for doubling the size of its resident crews.

Read his NASA biography here and Spaceflight Now+Plus subscribers can watch an extended pre-launch interview.
1154 GMT (7:54 a.m. EDT)
The astronauts are taking a few moments to gaze up at their spacecraft from the pad surface before ascending the tower.
1152 GMT (7:52 a.m. EDT)
Atlantis' 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 four-person crew to the 195-foot level to begin boarding the shuttle.
1147 GMT (7:47 a.m. EDT)
The AstroVan is passing the 52-story Vehicle Assembly Building where Atlantis 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.
1143 GMT (7:43 a.m. EDT)
The formal decision has been made to press ahead with today's launch attempt in hopes the weather cooperates at 11:26 a.m. EDT. At the moment, all launch weather rules are "go."
1136 GMT (7:36 a.m. EDT)
HERE COMES THE CREW. Space shuttle Atlantis' four veteran astronauts have departed Kennedy Space Center's crew quarters building for this morning's launch.

Commander Chris Ferguson, pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim are heading to pad 39A where they will climb aboard the orbiter today.
1134 GMT (7:34 a.m. EDT)
The astronauts are leaving the suitup room and heading down the hallway to board the elevator that will take them down to the AstroVan parked outside the Operations & Checkout Building in KSC's Industrial Area.
1131 GMT (7:31 a.m. EDT)
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 11:26:46 a.m. EDT launch time.
1118 GMT (7:18 a.m. EDT)
The final inspection team is departing the launch pad after its observations of the shuttle vehicle. No problems have been reported from the team.
1110 GMT (7:10 a.m. EDT)
The morning's launch weather forecast:

"Scattered showers associated with a tropical wave are prevalent over the Kennedy Space Center area and the saturated atmosphere will continue to breed showers and thunderstorms today. Our primary concerns for launch are showers and thunderstorms within 20 nautical miles of the Shuttle Landing Facility, flight through precipitation, and cumulus clouds."

Odds of acceptable weather this morning are just 30 percent favorable. The outlook improves to 60 percent tomorrow and 50 percent on Sunday.
1107 GMT (7:07 a.m. EDT)
Space shuttle Atlantis' astronauts are donning their day-glow orange launch and entry 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 at 7:36 a.m.
1047 GMT (6:47 a.m. EDT)
Current weather is "go" now.
1045 GMT (6:45 a.m. EDT)
Our launch webcast with Miles O'Brien, David Waters and space station commander Leroy Chiao is streaming live on this page.
1030 GMT (6:30 a.m. EDT)
Now "no go" for layered clouds and rain in Atlantis' flight path. We're coming up on a decision around 7:30 a.m. EDT on the weather conditions and whether to press ahead with today's launch attempt or stand down and preserve a shot tomorrow.
1000 GMT (6:00 a.m. EDT)
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 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.
0950 GMT (5:50 a.m. EDT)
The countdown remains on schedule and free of any problems for space shuttle Atlantis this morning. The weather is iffy and may very well come down to a real-time call a little after 11 a.m. today.

Recent activities in the countdown have included calibrations of the orbiter's inertial measurement units, powering up Atlantis' navigation systems, the pre-flight alignment of ground station antennas with the launch pad and communications checks with the Eastern Range.
0943 GMT (5:43 a.m. EDT)
And now the thick layered cloud rule is "red" again.
0924 GMT (5:24 a.m. EDT)
The launch weather rules are "go" across the board now. The previous violations for layered clouds and flight thru precip have cleared.
0915 GMT (5:15 a.m. EDT)
Here is a timeline of major events through the remainder of today's countdown:

HH...MM...SS...EDT...........EVENT

06...05...00...05:16 AM......Astronaut support comm checks
05...35...00...05:46 AM......Pre-ingress switch reconfig
04...51...00...06:30 AM......NASA TV launch coverage begins
04...25...00...06:56 AM......Final crew weather briefing
04...15...00...07:06 AM......Crew suit up begins
03...50...00...07:31 AM......Resume countdown (T-minus 3 hrs)

03...45...00...07:36 AM......Crew departs O&C building
03...15...00...08:06 AM......Crew ingress
02...25...00...08:56 AM......Astronaut comm checks
02...00...00...09:21 AM......Hatch closure
01...30...00...09:51 AM......White room closeout

01...10...00...10:11 AM......10-min built-in hold (T-20m)
01...00...00...10:21 AM......Test director countdown briefing
01...00...00...10:21 AM......Resume countdown (T-minus 20m)

00...59...00...10:22 AM......Backup flight computer to OPS 1
00...55...00...10:26 AM......KSC area clear to launch

00...49...00...10:32 AM......Begin final built-in hold (T-9m)
00...24...00...10:57 AM......NTD launch status verification
00...09...00...11:17:46 AM...Resume countdown (T-minus 9m)

00...07...30...11:19:16 AM...Orbiter access arm retraction
00...05...00...11:21:46 AM...Launch window opens
00...05...00...11:21:46 AM...Hydraulic power system start
00...04...55...11:21:51 AM...Terminate LO2 replenish
00...04...00...11:22:46 AM...Purge sequence 4
00...04...00...11:22:46 AM...Measurement units to inertial
00...03...55...11:22:51 AM...Aerosurface movement checks
00...03...30...11:23:16 AM...Main engine steering test
00...02...55...11:23:51 AM...LO2 tank pressurization
00...02...35...11:24:11 AM...Fuel cells to internal reactants
00...02...30...11:24:16 AM...Clear caution-and-warning memory
00...02...00...11:24:46 AM...Crew closes visors
00...01...57...11:24:49 AM...LH2 tank pressurization
00...00...50...11:25:56 AM...SRB joint heater deactivation
00...00...31...11:26:15 AM...Shuttle takes control of count
00...00...21...11:26:25 AM...SRB steering test
00...00...07...11:26:39 AM...Main engine start (T-6.6 seconds)
00...00...00...11:26:46 AM...SRB ignition (LAUNCH)
0911 GMT (5:11 a.m. EDT)
With the hazardous tanking operation now completed, the Orbiter Closeout Crew and Final Inspection Team have been dispatched to the pad to perform their jobs. The closeout crew will ready Atlantis' 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.
0906 GMT (5:06 a.m. EDT)
TANK FULL. Liquid oxygen has entered stable replenishment mode, officially completing today's three-hour external tank filling process.

For those of you keeping score at home, fueling began at 2:01 a.m. and concluded at 4:58 a.m. EDT.
0903 GMT (5:03 a.m. EDT)
A check of the current weather conditions shows "no go" conditions for thick layered clouds and rain in the shuttle's flight path.
0901 GMT (5:01 a.m. EDT)
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 11:26 a.m. EDT.
0848 GMT (4:48 a.m. EDT)
Liquid hydrogen loading has been completed. After reaching the 98 percent level at 4:02 a.m., the topping sequence began. And then the stable replenishment mode was activated at 4:34 a.m. to keep the tank full through the rest of the countdown, replacing the supercold propellant that naturally boils away.
0830 GMT (4:30 a.m. EDT)
No leakage is being seen around the ground umbilical carrier plate on the backside of shuttle Atlantis' external tank as the liquid hydrogen system is topped off.
0824 GMT (4:24 a.m. EDT)
The launch control team reports that the main fuel valve on space shuttle main engine No. 3 is working fine today. That valve was replaced after experiencing a leak during the special fueling test last month.
0745 GMT (3:45 a.m. EDT)
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.
0701 GMT (3:01 a.m. EDT)
All is going well an hour into the fueling operations for Atlantis. Both liquid oxygen and liquid hydrogen loading have switched to the "fast-fill" mode as fueling of the space shuttle proceeds via remote control at launch pad 39A.

The cryogenics flow from storage spheres at the pad, through feed lines to the mobile launcher platform, into Atlantis' aft compartment and finally into the external fuel tank.
0620 GMT (2:20 a.m. EDT)
The fueling sequence started with the chilldown of the liquid oxygen system at 2:01 a.m. EDT. The transfer lines on the liquid oxygen side will be chilled down, then the main propulsion system conditioning is completed.

The liquid hydrogen loading has transitioned from the chilldown thermal conditioning process to the "slow-fill" mode. This fills a small fraction of the tank, then the loading switches to "fast-fill" mode. The propellant started flowing into the tank at 2:12 p.m.
0606 GMT (2:06 a.m. EDT)
FUELING UNDERWAY. Today's filling of space shuttle Atlantis' external tank started on-time at 2:01 a.m. It will take three hours to get the half-million gallons of fuel aboard the shuttle for launch.
0601 GMT (2:01 a.m. EDT)
T-minus 6 hours and counting. The countdown has resumed ticking after a two-hour hold. The next scheduled built-in hold will occur at T-minus 3 hours.

Fueling should be getting underway shortly. No problems are being worked in the countdown this morning.
0601 GMT (2:01 a.m. EDT)
T-minus 6 hours and counting. The countdown has resumed ticking after a two-hour hold. The next scheduled built-in hold will occur at T-minus 3 hours.

Fueling should be getting underway shortly. No problems are being worked in the countdown this morning.
0557 GMT (1:57 a.m. EDT)
After looking at the weather and judging there's a chance Atlantis could launch today, the management team's pre-fueling meeting has granted approval to load a half-million gallons of supercold rocket fuel into the shuttle's external tank.
0430 GMT (12:30 a.m. EDT)
It's a soggy night at launch pad 39A, but all weather criteria for fueling Atlantis are acceptable to proceed. The conditions for the first hour of tanking starting at 2 a.m. will have cloudy skies with showers in the vicinity, light winds and a temperature of 79 degrees F.

And the latest forecast for launch remains at a 70 percent chance of weather prohibiting Atlantis from flying today due to thunderstorms in the area.

The latest outlook at the 11:26 a.m. EDT launch time is expected to include some scattered clouds at 3,000 feet, broken clouds at 8,000 and 25,000 feet, good visibility, south-southwesterly winds from a direction of 200 degrees of 10 knots gusting to 15 knots and a temperature of 80 degrees.

The odds for weather for Saturday and Sunday are 60 percent favorable and 50 percent, respectively.
0420 GMT (12:20 a.m. EDT)
Check out this great photo gallery of shuttle Atlantis being unveiled from the metal cocoon-like gantry Thursday afternoon!
0401 GMT (12:01 a.m. EDT)
T-minus 6 hours and holding. The countdown has gone into the scheduled two-hour built-in hold prior to the start of fueling. The Mission Management Team is scheduled to convene its critical pre-fueling meeting around 1:30 a.m. EDT.

A reminder that if you will be away from your computer but would like to receive occasional countdown updates, sign up for our Twitter feed to get text messages on your cellphone. U.S. readers can also sign up from their phone by texting "follow spaceflightnow" to 40404. (Standard text messaging charges apply.)

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2323 GMT (7:23 p.m. EDT)
"Put my last pages in my crew notebook. Time for bed. We'll give it our best shot tomorrow!" mission specialist Rex Walheim just tweeted.
2301 GMT (7:01 p.m. EDT)
T-minus 11 hours and counting. Clocks are running again after this half-day hold. The countdown will proceed to the next pause at T-minus 6 hours tonight.
2230 GMT (6:30 p.m. EDT)
Atlantis' four astronauts spent today studying flight plans and visiting with their families. They also received briefings on orbiter preparations, the payload status and the weather forecast from the ascent team of flight controllers in Houston.

They go to sleep at 8:30 p.m. EDT and will be awakened for launch day at 4:30 a.m. EDT. They'll have breakfast at 5 a.m. and then undergo final medical exams at 5:45 a.m. Suit up begins just after 7 a.m. and departure from crew quarters is scheduled for 7:36 a.m. in preparation for blastoff at 11:26 a.m. EDT.
2145 GMT (5:45 p.m. EDT)
The engineering board determined there were no issues with lightning strike and shuttle Atlantis' countdown can proceed as scheduled.
2035 GMT (4:35 p.m. EDT)
NASA says the engineering review board meeting about the lightning strike has begun.
2015 GMT (4:15 p.m. EDT)
As predicted, thunderstorms rumbled across the Kennedy Space Center Thursday and at least one lightning bolt struck launch pad 39A where the shuttle Atlantis is being prepared for takeoff Friday on NASA's 135th and final shuttle mission.

Magnetic field readings at the pad exceeded normal limits in four locations, sources said, prompting engineers to schedule a review board meeting at 4:30 p.m. to make sure no sensitive systems were affected. How long the review might take and what impact, if any, it might have on launch preparations was not immediately clear.

Read our full story.
1920 GMT (3:20 p.m. EDT)
On the day before her last launch, the space shuttle Atlantis has been unveiled from the cocoon-like service gantry at Kennedy Space Center's pad 39A for liftoff.

Technicians will spend the next few hours getting ground equipment configured and secured in preparation for tonight's fueling with supercold rocket propellant. Inside Atlantis' cockpit, meanwhile, support personnel will verify all of the switches are in the correct positions for ascent.

Clocks resume counting at 7:01 p.m. EDT after the half-day hold at T-minus 11 hours. The orbiter's fuel cells will be activated about an hour later, and the hazard area around the pad is scheduled to be cleared of all workers by 11:15 p.m.

The next planned hold is T-minus 6 hours beginning at 12:01 a.m. EDT. During this two-hour pause of the clocks, the Mission Management Team convenes its pre-fueling meeting around 1:30 a.m. to review the status of work, the readiness of shuttle systems and the latest weather forecast.

If all goes according to plan, loading of the external tank with propellant will start at 2:01 a.m. EDT. The process should take three hours to complete.

Join us here in the Mission Status Center for live play-by-play updates throughout the morning. And don't miss our launch webcast with Miles O'Brien, David Waters, former space station commander Leroy Chiao and several special guests that begins at 6:30 a.m. EDT (1030 GMT).

Liftoff time is 11:26 a.m. EDT (1526 GMT) as Atlantis sets sail on the space shuttle program's final voyage.

A reminder that if you will be away from your computer but would like to receive occasional countdown updates, sign up for our Twitter feed to get text messages on your cellphone. U.S. readers can also sign up from their phone by texting "follow spaceflightnow" to 40404. (Standard text messaging charges apply.)

And check out Spaceflight Now's Facebook page!
1916 GMT (3:16 p.m. EDT)
The gantry has arrived in its parking spot for launch.
1905 GMT (3:05 p.m. EDT)
The structure is nearing its launch position.
1856 GMT (2:56 p.m. EDT)
After initially moving at a glacial pace, the speed has picked up and the massive gantry is clear of the shuttle now as it continues to back away.
1845 GMT (2:45 p.m. EDT)
Rollback of the rotating service structure to reveal shuttle Atlantis has started at launch pad 39A. You can watch the tower retraction in our live streaming video.
1830 GMT (2:30 p.m. EDT)
The observers are on station, checks are complete and the pathway that the rotating structure will follow has been cleared of personnel. The move is expected to begin shortly.
1820 GMT (2:20 p.m. EDT)
The official launch window for Friday's shot at getting space shuttle Atlantis into orbit for docking with the International Space Station extends for 10 minutes and 1 second.

Based on the latest radar tracking of the space station's orbit and update from Mission Control, the single-pane window leading to rendezvous on Flight Day 3 will open at 11:21:46 and lasts until 11:31:47 a.m. EDT.

The targeted liftoff time occurs in the middle of the period at 11:26:46 a.m. EDT. That's the moment when Earth's rotation carries the launch pad into the plane of the station's orbit.

At the preferred liftoff time, the International Space Station will be flying 232 statute miles over the Pacific Ocean, east of Christchurch, New Zealand.

We have posted our countdown timeline and launch events pages with this liftoff time.

If liftoff slips to Saturday for some reason, the backup launch opportunity offers a window of 10:59:15 to 11:09:16 a.m. EDT. The preferred launch time would be 11:04:15 a.m. EDT.

At that liftoff Saturday, the International Space Station will be flying 232 statute miles over the Pacific Ocean, east of Prince Edward Island, Canada.

If liftoff slips to Sunday, the backup launch opportunity offers a window of 10:33:31 to 10:43:31 a.m. EDT. The preferred launch time would be 10:38:31 a.m. EDT.

At that liftoff Sunday, the International Space Station will be flying 232 statute miles over the Indian Ocean, southwest of Sri Lanka.
1745 GMT (1:45 p.m. EDT)
NASA says that lightning strike that the team is evaluating occurred within one-third of a mile from the pad. Engineers are determining if any additional inspections are required before the gantry can be cleared for rollback.
1737 GMT (1:37 p.m. EDT)
The revised plan calls for the gantry rollback observers to get in position at 1:55 p.m. EDT. That typically occurs about 45 minutes before the tower actually begins to roll.
1721 GMT (1:21 p.m. EDT)
With the Phase 2 lightning warning no longer posted, the launch pad is open for workers to resume normal activities again.
1714 GMT (1:14 p.m. EDT)
The shuttle team is assessing a lightning strike that occurred close to the pad.
1704 GMT (1:04 p.m. EDT)
The weather team is predicting the lightning warning should be dropped around 1:15 p.m. EDT, allowing the pad technicians to resume their work at the launch pad.
1633 GMT (12:33 p.m. EDT)
A weather advisory for heavy rain has been posted for the Cape.
1625 GMT (12:25 p.m. EDT)
It's a tropical downpour at the launch pad now.
1555 GMT (11:55 a.m. EDT)
The lightning warning remains in place. There's no firm estimate on when the weather will allow preparations to resume for the launch pad gantry rollback.
1516 GMT (11:16 a.m. EDT)
And now a Phase 2 lightning advisory has been declared, meaning workers at launch pad 39A should take cover. The planned 11:15 a.m. duty time for observers getting on station for gantry rollback has been postponed.
1514 GMT (11:14 a.m. EDT)
Although the pad crew had been working to get the gantry ready for retraction as early as 12 noon, the timing depends on the weather. There's some stormy conditions now moving in.
1509 GMT (11:09 a.m. EDT)
The weather team has posted a lightning watch for all areas of the Kennedy Space Center.
1450 GMT (10:50 a.m. EDT)
All systems are "go" for tomorrow's launch of the final space shuttle as the countdown continues to tick smoothly at the Kennedy Space Center. But will the weather cooperate?

"Our last couple days out at the launch pad have gone extremely well. We've gotten a lot of work done and we're proceeding on the timeline as we had hoped," said Jeff Spaulding, NASA test director.

But it's the weather that's posing the main concern for flying Atlantis at 11:26 a.m. EDT tomorrow.

"The weather is not looking good for launch," says weather officer Kathy Winters. "As you can see outside, the clouds have rolled in, we're starting to see some showers, we even had a thunderstorm show up this morning along Cocoa Beach. We are expecting more of this the next couple of days."

A key milestone will occur at 1:30 a.m. EDT when the Mission Management Team gathers for its pre-fueling meeting to assess the progress of work and the latest weather forecast before making a "go" or "no go" decision to fill Atlantis' external tank.

Hoping for breaks in the weather and a sufficient hole to launch, NASA officials can decide to fuel the shuttle and take the countdown all the way to T-minus 9 minutes just to see how the conditions play out in reality.

"Our goal going into the meeting tonight is always to try to tank. Our goal is to do what we can to get to that launch attempt," said Spaulding.

"It's a really tough day if you make (an early) decision to not go and it turns out to be good weather. And we've seen those kinds of things in the past."
1425 GMT (10:25 a.m. EDT)
Rollback of the rotating service structure to reveal shuttle Atlantis could occur sooner than originally expected as NASA works around the weather today. The plan calls for final walkdown inspections of the pad starting now, observers at their duty posts around 11:15 a.m. and gantry retraction potentially starting as early as 12 noon EDT. But it all depends on the weather and the completion of work.
1235 GMT (8:35 a.m. EDT)
The weather forecast remains unchanged for tomorrow's launch with still only a 30 percent chance of acceptable conditions.

Here's the description from the meteorologists:

"Moisture continues to increase over Kennedy Space Center as a trough of low pressure moves in from the south-southeast. An upper-level low in the Gulf of Mexico is also advecting clouds associated with convection in from the southwest. Scattered showers are prevalent over the area this morning, and the saturated atmosphere will continue to breed showers and thunderstorms for the next several days with the most activity today and launch day," forecasters say.

"Our primary concerns for launch are showers and thunderstorms within 20 nautical miles of the Shuttle Landing Facility, flight through precipitation, and cumulus clouds."

The specifics call for scattered low- clouds, broken decks in the mid high levels, showers and thunderstorms in the vicinity, good visibility, south-southwesterly winds of 10 peaking to 15 knots and a temperature of 80 degrees.

If Atlantis' launch slips to Saturday for some reason, the odds of acceptable weather increase slightly to 40 percent and then improve to 60 percent on Sunday.

"Due to the launch time moving earlier, the trough moving north of the area, and a slightly dryer atmosphere, the threat of weather decreases each day," forecasters say. "Still, cumulus clouds and showers are concerns for each launch window through the weekend."
1200 GMT (8:00 a.m. EDT)
Shuttle Atlantis remains poised for blastoff tomorrow at 11:26 a.m. EDT (1526 GMT) on a 12-day flight to deliver logistics and goods to the International Space Station.

Final tests of the avionics, pneumatics and controllers for the three main engines were conducted overnight. Countdown clocks then entered the lengthy T-minus 11 hour planned hold period at 5 a.m. That built-in hold should last 14 hours and 1 minute.

Today's chores at launch pad 39A are focused on functional checks of the orbiter's star trackers, activating the inertial measurement units, thoroughly testing the communications network, loading the last items into the crew module, filling of the launch pad's sound suppression system water tank and installing film in pad cameras.

The giant gantry-like rotating service structure is scheduled for retraction from around Atlantis this afternoon. Fueling of the shuttle's giant external tank begins tomorrow at 2:01 a.m. EDT.

A reminder that if you will be away from your computer but would like to receive countdown updates, sign up for our Twitter feed to get text messages on your cellphone. U.S. readers can also sign up from their phone by texting "follow spaceflightnow" to 40404. (Standard text messaging charges apply.)

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0100 GMT (9:00 p.m. EDT Wed.)
T-minus 19 hours and counting! The countdown has resumed from the scheduled four-hour-long hold following the fuel cell reactant loading operations today. Clocks will continue ticking until reaching the half-day hold planned at the T-minus 11 hour mark starting at 5 a.m. EDT.
WEDNESDAY, JULY 6, 2011
NASA is readying the shuttle Atlantis for launch Friday on the iconic program's 135th and final flight, bringing the curtain down on one of the nation's greatest technological triumphs after more than three decades at the apex of manned spaceflight.

Read our 8-part special report.
2120 GMT (5:20 p.m. EDT)
Forecasters are predicting a 70 percent chance of showers and thunderstorms Friday that could delay launch of the shuttle Atlantis. But barring a dramatic change for the worse, the chairman of NASA's mission management team says he plans to press ahead with flight preparations.

Read our full story.
2100 GMT (5:00 p.m. EDT)
Countdown clocks have hit the next in the series of pre-planned built-in hold points. This pause at T-minus 19 hours will last through 9 p.m. EDT.
2010 GMT (4:10 p.m. EDT)
The cryogenic reactants for the space shuttle's electricity-generating fuel cells were successfully loaded aboard Atlantis during a multi-hour operation at pad 39A today.

Space shuttle main engine checkouts will be performed tonight while other pad technicians continue work to button up the orbiter and ground support equipment for launch.

Liftoff remains targeted for Friday at 11:26 a.m. EDT (1526 GMT).

"It's like a big sporting event game day. Friday is game day for us, so we don't want to wait till Saturday. We want to play the game Friday," shuttle launch director Mike Leinbach says.

Our live launch webcast hosted by Miles O'Brien, David Waters and former astronaut Leroy Chiao begins Friday at 6:30 a.m. EDT (1030 GMT) from the Kennedy Space Center's Press Site. Join us for the show!
1820 GMT (2:20 p.m. EDT)
Check out the updated Atlantis launch windows chart for the latest time tweaks including a change to Saturday's opportunity.
1730 GMT (1:30 p.m. EDT)
The Atlantis astronauts were awakened at 4 a.m. EDT while continuing to shift their sleep patterns to match the work hours of the mission. More Shuttle Training Aircraft and T-38 jet flights were planned today, plus the crew's pre-flight medical exams. They will go to sleep at 8 p.m.
1550 GMT (11:50 a.m. EDT)
The Mission Management Team gathered this morning for its pre-launch meeting and verified all systems remain "go" for shuttle Atlantis' blastoff Friday at 11:26 a.m. EDT.

"We had a really smooth Mission Management Team meeting today at the launch-minus-two-day point. Went through the agenda, talked to all the parties involved, nobody has any issues that are in work," says pre-launch MMT chairman Mike Moses.

Out at launch pad 39A, the primary focus today is filling the fuel cell storage spheres aboard the space shuttle with liquid oxygen and liquid hydrogen this morning and into this afternoon. The devices combine the cryogenic reactants to generate electricity to power Atlantis during the mission and produce drinking water as a byproduct for the astronauts.

"The countdown so far is going extremely well. We're into the loading of the fuel cell system right now. That's the liquid oxygen and liquid hydrogen that powers those fuel cells. That should be done around dinnertime this evening and we'll deconfigure from that and get back into other launch pad preparations," shuttle launch director Mike Leinbach says.

"The vehicle is in fantastic shape. Mike has the launch team keyed up and ready to go. They are doing perfect, everything is on time, on schedule, looking amazing," Moses added.

The fuel cells will give NASA three days to launch Atlantis -- Friday, Saturday and Sunday -- before the cryogenic supplies aboard the shuttle would need to be replenished. That servicing scenario takes a few days.
1300 GMT (9:00 a.m. EDT)
The countdown has resumed ticking after the pre-planned four-hour hold at the T-minus 27 hour mark. Activities remain on track for launching Atlantis this Friday, weather permitting. Overnight, technicians performed standard powerups and checkouts of the orbiter's avionics and navigation aids with no problems reported.
1205 GMT (8:05 a.m. EDT)
The weather outlook for Friday has worsened to just a 30 percent chance that conditions will be good enough to launch Atlantis. Thunderstorms around the Kennedy Space Center will be the concern for the 11:26 a.m. EDT launch time.

The odds improve slightly to 40 percent favorable on Saturday and jump to 60 percent on Sunday.

"High clouds are streaming into the area from the southwest associated with convection in the Southeast Gulf of Mexico caused by an upper level low. Easterly flow continues today which will cause any developing weather to remain inland. A tropical wave in the Bahamas is moving west-northwest and will impact Florida on Thursday, increasing moisture and bringing scattered showers and isolated thunderstorms by Thursday afternoon and evening," forecasters reported this morning.

"By Friday, the wave will merge over Florida with an upper level trough, causing the wave to stall over the Florida area. This will bring significant cloud cover with embedded showers and isolated thunderstorms causing concerns for launch weather. Our primary concerns for launch are showers and thunderstorms within 20 nautical miles of the Shuttle Landing Facility, flight through precipitation, and cumulus clouds.

"Due to the launch time moving earlier and a slightly dryer atmosphere each day, the threat of weather decreases each day; therefore, the probability of Kennedy Space Center weather prohibiting launch decreases as well."

Meanwhile, testing of the shuttle's pyrotechnic initiator controllers and range safety systems have been completed this morning. Final preps for today's fuel cell loading are underway.

Also upcoming today is the pre-launch meeting of the Mission Management Team to give final approval to proceed with Atlantis' flight. After the meeting concludes, NASA will hold a news conference around 11:30 a.m. EDT.
0900 GMT (5:00 a.m. EDT)
The countdown has entered a planned four-hour hold at the T-minus 27 hour mark. This pause will last through 9 a.m. EDT ahead of the fuel cell servicing work.

Liquid hydrogen and liquid oxygen for Atlantis' electricity-generating fuel cells will be loaded into storage spheres beneath payload bay today as standard countdown work continues at pad 39A.

The tankers will be hooked up this morning and the offload into the shuttle should start around 10:30 a.m. EDT and proceed through the late afternoon.

The cryogenic reactants are combined by the three onboard fuel cells to produce power and a byproduct of drinking water during the shuttle's mission.

Technicians flow the cryogenics into small tanks aboard the orbiter during a multi-hour operation. Later this evening, they will demate the pad umbilical system used in the loading process and stow that equipment.

Clocks will continue until the next hold point at T-minus 19 hours starting at 5 p.m., which is when the ground team wrap up the fuel cell operations.
TUESDAY, JULY 5, 2011
As we prepare to say goodbye to the space shuttle, let's take a moment to reflect on the ship that will sail the final voyage this week with a look at Atlantis' history and a special photo tribute as she stands on the launch pad one last time.

Read our full story.

And see our photo gallery.
2130 GMT (5:30 p.m. EDT)
Countdown clocks began ticking Tuesday for the shuttle Atlantis' launch Friday on NASA's 135th and final shuttle mission, a flight to deliver more than 8,000 pounds of supplies and equipment to the International Space Station.

Read our full story.
1700 GMT (1:00 p.m. EDT)
COUNT BEGINS. Clocks at the Kennedy Space Center just began ticking down to Friday's scheduled launch of Atlantis on the shuttle program's final trek to space.

The official countdown sequence started at 1 p.m. EDT inside Firing Room 4 of the Complex 39 Launch Control Center. Launch team members had gathered for the "call-to-stations" at 12:30 p.m.

The count commenced from the T-minus 43 hour mark. But a series of pre-planned holds are timed throughout the next few days, leading to the targeted liftoff time of 11:26 a.m. EDT.

The weather forecast looks somewhat iffy for the launch opportunity, but there are no hardware worries being worked as the count starts.

Activities planned during the early portion of the countdown for shuttle workers include buttoning up launch pad equipment and removing platforms inside the orbiter's crew module, reviewing flight software stored in Atlantis' mass memory units, loading backup software into the general purpose computers and testing navigation systems. Loading of cryogenic reactants into the orbiter's power-generating fuel cells will occur tomorrow.
1430 GMT (10:30 a.m. EDT)
"All of our vehicle and ground systems are ready, the STS-135 crew, Atlantis and launch team are all ready to proceed. We are looking forward to getting underway with the count, leading to a spectacular launch on Friday morning," says Jeremy Graeber, NASA test director.

Clocks will begin ticking today at 1 p.m. EDT for the three-day countdown sequence to Friday's planned launch of Atlantis.

"Our teams here at Kennedy Space Center and all NASA centers around the country have been working for over a year to prepare Atlantis, the external tank, our solid rocket boosters, the payload and all of our ground systems for the STS-135 mission," Graeber said. "All of our preparations for the launch countdown have been completed or are in work. And we are working no issues at this time."
1345 GMT (9:45 a.m. EDT)
Get a live update on shuttle Atlantis preparations and hear from the launch weather officer in the NASA news briefing beginning at 10 a.m. EDT in our streaming video.
1215 GMT (8:15 a.m. EDT)
The early weather outlook issued moments ago by the launch meteorology team gives a 40 percent chance for Atlantis to fly on Friday as planned. The potential for showers and thunderstorms plus cumulus clouds around Kennedy Space Center will be concerns to watch.

The specifics call for scattered low- and mid-level clouds, a broken deck of high clouds, isolated showers and thunderstorms in the vicinity, good visibility, southeasterly winds of 8 knots and a temperature of 81 degrees.

"The Bermuda high pressure ridge is slightly north of the area, and weak, east winds will cause showers and thunderstorms to develop along the sea breeze inland today. The majority of the weather will remain inland, with just a 30 percent chance a storm will move into the Kennedy Space Center (KSC) area this afternoon. Weather will be similar tomorrow, as well," forecasters report.

"A tropical wave in the vicinity of the Turks and Caicos Islands is moving west-northwest and will impact Florida on Thursday, increasing moisture and bringing scattered showers and isolated thunderstorms by Thursday afternoon and evening.

"By Friday, the wave will move off to the northwest, but the residual moisture will provide the ingredients necessary for showers and thunderstorms to develop as the sea breeze forms Friday late morning. Our primary concerns for launch are showers and thunderstorms within 20 nautical miles of the Shuttle Landing Facility and cumulus clouds near the flight path.

"The same concerns exist for the following two days, but due to the launch time moving earlier and a slightly dryer atmosphere on Sunday, the threat of sea breeze development during the launch window decreases each day; therefore, the probability of KSC weather prohibiting launch decreases as well," forecasters say.

If Atlantis' launch slips to Saturday for some reason, the odds of acceptable weather increase to 60 percent and then improve to 70 percent on Sunday.
MONDAY, JULY 4, 2011
The crew of the shuttle Atlantis celebrated the July Fourth holiday Monday by flying to Florida aboard sleek T-38 jet trainers to prepare for launch Friday on the 135th and final shuttle mission.

Read our full story.
1845 GMT (2:45 p.m. EDT)
This was it. The last time a space shuttle crew will jet into the Kennedy Space Center to begin their countdown. And no one knows when the next time astronauts will come to the Florida spaceport to be launched from the planet.

Commander Chris Ferguson, pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim today traveled from their home base in Houston to the Kennedy Space Center launch site in sleek T-38 jets, trained and ready to take Atlantis on the final space shuttle mission.

"We're delighted to be here after a very arduous nine-month training flow. We're thrilled to finally be here in Florida for launch week," Ferguson said.

On this Fourth of July, each of the crew members had American flags waving in their hands as they addressed the large crowd of reporters at the runway.

"We have a very event-filled mission ahead of us. We have 12 days. We'll be very, very busy. As you can tell we have an abridged crew (of just four). And when it's all over I think we'll all be proud to put the righthand bookend on the space shuttle program," Ferguson said.

The crew will have some study time this afternoon before heading to sleep at 8 p.m. EDT, then be awakened at 4 a.m. Tuesday for Ferguson and Hurley to fly landing approaches into KSC's runway using Shuttle Training Aircraft. The entire crew will spend time later in the day reviewing the flight data files and checking their launch and entry spacesuits.

Atlantis' three-day launch countdown sequence begins Tuesday at 1 p.m. EDT. All activities remain on schedule for Friday's 11:26 a.m. EDT blastoff.

The next streaming video event is planned for Tuesday morning at 10 a.m. EDT when NASA holds a status update and weather briefing. You can watch it right here on this page.
1836 GMT (2:36 p.m. EDT)
Shuttle launch director Mike Leinbach is on hand to greet the astronauts as they step out of the T-38s.
1832 GMT (2:32 p.m. EDT)
Touchdown! Space shuttle Atlantis' four astronauts have arrived for Friday's scheduled launch. The aircraft are taxiing down the runway now. Live video of the crew's comments is coming up.
1830 GMT (2:30 p.m. EDT)
"Clear to land."
1828 GMT (2:28 p.m. EDT)
The pair of T-38s just swung around launch pad 39A where space shuttle Atlantis stands poised for blastoff on Friday.
1819 GMT (2:19 p.m. EDT)
Commander Chris Ferguson has established voice communications with the KSC runway tower. He reports the crew is about 15 minutes away. They plan to buzz launch pad 39A before setting up for landing on Runway 15.
1810 GMT (2:10 p.m. EDT)
The astronauts are flying in two T-38 jets:
  • Tail number 961: Commander Chris Ferguson and mission specialist Sandy Magnus
  • Tail number 921: Pilot Doug Hurley and mission specialist Rex Walheim
1750 GMT (1:50 p.m. EDT)
Reporters and photographers have gathered at the Shuttle Landing Facility to cover the astronauts' arrival a short time from now. It's an interesting way to spend the Fourth of July.
1738 GMT (1:38 p.m. EDT)
The crew has taken off from Mobile for this second leg of their travels to Kennedy Space Center today. The latest predicted arrival time is about 2:30 p.m. EDT. We'll show it live here.
1715 GMT (1:15 p.m. EDT)
The astronauts have reached their refueling stop in Mobile, Alabama. NASA still projects the crew will arrive at Kennedy Space Center around 2:45 p.m. EDT.
1612 GMT (12:12 p.m. EDT)
Flying in a pair of sleek T-38 jets, the space shuttle Atlantis astronauts have departed from Ellington Field near the Johnson Space Center in Houston for today's trip over to the Kennedy Space Center to begin this week's launch preparations.

Commander Chris Ferguson, pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim will make a refueling stop in Mobile, Alabama, before arriving at the Florida spaceport around 2:45 p.m. EDT (1845 GMT).

We will have live streaming video of the arrival event, which will include comments from the crew.
SUNDAY, JULY 3, 2011
Fergie, Chunky, Sandy and Rex. You can call them "the final four." They are the astronauts chosen to launch Atlantis into orbit Friday for the space shuttle program's grand finale.

Get to know Atlantis' crew.
SATURDAY, JULY 2, 2011
A week from now, the shuttle Atlantis astronauts will be in space. But they are spending this Saturday in medical quarantine at the Johnson Space Center.

"We are now in quarantine here at JSC. Not a bad jail. Good food. Good gym. But LOTS of shuttle checklists screaming at us to be read," mission specialist Rex Walheim tweeted this morning.

Talking with reporters on Thursday, commander Chris Ferguson said he was wanted some quiet time that quarantine would provide him.

"The crew, we've been enormously busy, especially here in the last month or so. Personally, I'm looking forward to quarantine to set down a little bit, gather some of my thoughts, take a few notes and review some of things that I've desperately needed to review for the last couple of weeks," Ferguson said.

Out at launch pad 39A, shuttle Atlantis is powered down for the holiday break. No work is scheduled at the Florida spaceport this weekend.
FRIDAY, JULY 1, 2011
Space shuttle Atlantis' three-level aft engine compartment has been buttoned up for launch and the access doors on either side of the orbiter are now installed and sealed as the team heads into some time off for the holiday weekend.

Meanwhile, the four astronauts have completed their training regimen in Houston, performing the final launch and ascent procedure runs inside the motion based simulator today before entering preflight medical quarantine tonight.

"Going into quarantine in a few hours. Time for a last meal out somewhere," mission specialist Sandy Magnus tweeted.

The crew is scheduled to arrive at the Kennedy Space Center on Monday around 2:45 p.m. EDT in advance of the countdown clocks starting on Tuesday.

Liftoff remains on schedule for next Friday at 11:26 a.m. EDT.

Our special live launch day webcast anchored by Miles O'Brien begins at 7 a.m. EDT.
THURSDAY, JUNE 30, 2011
Flight pressurization of the gaseous helium and nitrogen systems for Atlantis' orbital maneuvering system engine pods and reaction control thrusters, plus the main propulsion system pressure vessels was successfully completed last night and into this morning.

This pre-flight charging of the high-pressure gas bottles for the hypergolic and propulsion systems is one of the final major milestones heading into next week's launch countdown.

Mission officials and the astronauts held their flight preview news briefings at the Johnson Space Center in Houston today, giving reporters a thorough insight plans for Atlantis' 12-day voyage to the International Space Station.

"I can't think of too many more places I'd rather be than in the space shuttle flight control room leading those troops into a fierce battle with gravity one last time," said Kwatsi Alibaruho, the mission's lead shuttle director.

"We very much appreciate what the space shuttle program has done for us, the national capability we gained through it, the knowledge we've gained through it."

The astronauts will conduct their final training activities tomorrow and then go into medical quarantine.

"Leading up to the final launch, eight days away. It does sound so final. I don't think we want any more time, though. We're ready, we're trained, we want to go do it, and we want to do it on-time," commander Chris Ferguson says.

NASA has published the STS-135 press kit. Download PDF.
WEDNESDAY, JUNE 29, 2011
The 60-foot-long payload bay doors of space shuttle Atlantis were swung shut and latched for flight at launch pad 39A today. The next time the doors will be opened is in orbit, about 90 minutes after launch.

Atlantis is carrying the Raffaello cargo-delivery module and a robotic satellite refueling demonstrator payload for the International Space Station, plus a tiny PicoSat that will be ejected from the payload bay.

See photo gallery.
TUESDAY, JUNE 28, 2011
Senior NASA officials held the final space shuttle flight readiness review at the Kennedy Space Center today and affirms plans to launch Atlantis next week as scheduled.

Read our full story.
1849 GMT (2:49 p.m. EDT)
Today's Flight Readiness Review has concluded with a unanimous "go" for launch of Atlantis next Friday, July 8 at 11:26 a.m. EDT. Senior managers reviewed the readiness of the space shuttle and International Space Station for the mission to deliver a year's worth of supplies.

A post-meeting news conference with NASA officials from the Kennedy Space Center is expected at 3:30 p.m. EDT today. We'll have live streaming video coverage on this page.
1745 GMT (1:45 p.m. EDT)
After a break for lunch, managers finished SRB topics and then moved into the orbiter and ground processing review status.
1630 GMT (12:30 p.m. EDT)
The morning session of the Flight Readiness Review received briefings from the mission operations folks who will run STS-135 from Houston and discussed the status of life-support elements aboard the space station. They've also assessed the recent external fuel tank and solid rocket booster performance.
1230 GMT (8:30 a.m. EDT)
The Flight Readiness Review is underway today at the Kennedy Space Center. Senior officials are examining all aspects of mission preparations to ensure space shuttle Atlantis, the astronauts and payloads are ready to go fly the STS-135 mission, as well as the International Space Station is ready to receive this flight.

The meeting will culminate with managers setting the formal launch date. The shuttle is targeting blastoff in 10 days.

NASA plans to hold a post-FRR news conference this afternoon. The exact start time has not been determined. We'll post updates on this page and dispatch Twitter alerts as further details become available.
MONDAY, JUNE 27, 2011
Inspections of space shuttle Atlantis' external fuel tank have verified that the ship is crack-free and ready to launch. Modifications to the ribbed intertank region between the liquid oxygen and liquid hydrogen sections of the external tank were implemented to strengthen support beams, some of which cracked on the previous tank used by Discovery in February. A special fueling test on Atlantis earlier this month subjected the beefed up tank to cryogenic conditions as a precautionary step to see any cracks would develop. Digital X-rays taken this past week confirm no problems exist.

Meanwhile, retesting of main engine No. 3 after the hydrogen fuel valve was replaced has been accomplished. Technicians have begun buttoning up the engine and the orbiter's aft compartment now after running the readiness test and pumping helium through the system to look for leakage.

Atlantis' astronauts are kicking off their final week of training in Houston today by conducting re-entry simulations. They go into pre-flight medical quarantine on Friday, then fly to Kennedy Space Center next Monday.


Read our earlier status center coverage.

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