Mission Status Center

After nasty storms blew across Kennedy Space Center earlier this week, precautionary inspections of space shuttle Endeavour and the external fuel tank were performed at launch pad 39A. Only superficial marks were seen on the tank's foam during initial looks, as seen in this gallery of images snapped from Friday's high-definition video. Further inspections were planned on Saturday.
See the photo gallery.

The Endeavour astronauts followed a realistic countdown sequence today, getting suited up and strapping inside the space shuttle for a thorough dress rehearsal that culminated with a pretend ignition and shutdown of the three main engines at T-minus 4 seconds.

Read our full story.

And check out this photo gallery from today.

The crew just drove by the Press Site.

This will conclude our live play-by-play reports of today's successful countdown dress rehearsal for the space shuttle. The astronauts are scheduled to return to Houston this afternoon to complete their final two weeks of training there. They'll be back in Florida on April 15 for the real countdown to blastoff.

The Astrovan is departing launch pad 39A to drive Endeavour's astronauts to Kennedy Space Center's crew quarters building.

The crew has taken into the elevator from the 195-foot-level of the pad tower down to the ground.

The Astrovan is parked at the launch pad to retrieve the crew after they finish things on the tower.

All six astronauts have exited Endeavour and headed for the slidewires on the west side of the pad's tower to practice hopping into the baskets while wearing their launch suits and helmets. The crew uses the buddy system in scurrying to the baskets in pairs.

And there went the commander and pilot.

All four mission specialists are off the vehicle.

The crew is beginning to egress Endeavour, all still wearing their helmets.

"Mode 1 egress" declared for the crew to exit the shuttle now.

Once the astronauts finish their post-countdown work, they will climb out the hatch and practice hurrying to the slidewide baskets on the opposite side of the launch tower. These baskets would be used to evacuate the crew to the ground where a fortified bunker awaits. They won't actually ride the baskets today, however.

The launch team is completing initial safing of Endeavour and the launch pad following the main engine shutdown rehearsal. The team members are going through the procedures they would use if such a situation happened on launch day. In reality, there have been five such aborts in shuttle history, the most recent in 1994.

Today's countdown demonstration has concluded with the simulated ignition and shutdown of Endeavour's three main engines. This is known as a Redundant Set Launch Sequencer abort, indicating the shuttle's onboard computers detected a problem during engine start that forced an emergency stop of the countdown before solid rocket booster ignition.

CUTOFF! The countdown has been halted at T-minus 4 seconds as planned in today's simulation. Safing is in progress to rehearse a pad abort scenario for the space shuttle.

T-minus 10 seconds. "Go" for main engine start.

T-minus 31 seconds. Auto sequence start! The handoff has occurred from the Ground Launch Sequencer to the space shuttle. Endeavour's computers now controlling the final half-minute of the countdown.

T-minus 1 minute. Computers would verify that the main engines are ready for ignition, the sound suppression water system would be armed to activate at T-minus 16 seconds to dampen the sound produced at launch and the residual hydrogen burn ignitors would be armed to fire at T-minus 10 seconds to burn off hydrogen gas from beneath the main engine nozzles.

T-minus 90 seconds.

The countdown has resumed after a 35-second hold.

T-minus 1 minute, 57 seconds and holding. The launch team has stopped the clock at one of the several milestones available for holding the countdown. Once the count passes this point on launch day, the liquid hydrogen tank is pressurized.

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

T-minus 2 minutes, 45 seconds. The external tank liquid oxygen tank pressurization simulation has started.

T-minus 3 minutes, 30 seconds. Normally at this point in a real countdown, the aerosurfaces and main engine nozzles of Endeavour would be moved through computer-controlled test patterns to demonstrate their readiness to steer the vehicle during launch. However, none of these activities happen today.

T-minus 4 minutes. Activation of the APUs is complete with three units simulated to be up and running. Also, the orbiter's heaters have been configured for launch by commander Mark Kelly.

The final helium purge sequence is underway in the main propulsion system. This procedure readies fuel system valves for engine start.

Now targeting a 2:05:01 p.m. launch time.

T-minus 5 minutes and counting again after a 42-second hold. The "go" has been given for the simulated Auxiliary Power Unit start. Pilot Greg Johnson would flip three switches in Endeavour's cockpit to start each of the three APU's. The units, located in the aft compartment of Endeavour, 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 are moving the orbiter's aerosurfaces, gimbaling the main engine nozzles and deploying the landing gear.

T-minus 5 minutes and holding. The clock has stopped briefly as part of the test to demonstrated the launch team's ability to work problems at the countdowns various hold points.

T-minus 6 minutes. Pilot Greg Johnson has been asked by the orbiter test conductor to simulate pre-starting 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 is simulating retraction of the Orbiter Access Arm from the crew hatch on the the vehicle. The arm was the passage way for the astronauts to board Endeavour earlier today.

T-minus 9 minutes and counting. The Ground Launch Sequencer is now controlling the final phase of today's countdown to the pretend launch of space shuttle Endeavour at 2:04:19 p.m. EDT.

The launch team and crew are being polled now and the countdown will resume shortly.

Clocks remain holding at T-minus 9 minutes, pushing back the mock liftoff time beyond 2:00 p.m.

Now half-way through this planned hold. Final readiness polls are coming up. It is a beautiful afternoon at the Florida spaceport and all weather rules are "go" for launch.

T-minus 9 minutes and holding. The next pause point in the countdown has been reached. This hold is scheduled to last 10 minutes.

Commander Mark Kelly has enabled the abort steering instrumentation while pilot Greg Johnson configured the displays inside Endeavour's cockpit for launch. Johnson also simulated reconfiguring the main propulsion helium system.

Shuttle Endeavour will be taking her 25th and final spaceflight after 19 years of service to America. The vehicle's rich history (to date) includes 280 days in space, or precisely 6,729 hours, 39 minutes and 44 seconds spent in flight.

The missions have spanned 4,429 orbits of Earth and accumulated 103,149,636 miles.

Endeavour's maiden voyage in May 1992 was a dramatic adventure to rescue the wayward Intelsat 603 telecommunications satellite that required the astronauts to improvise with the first-ever three-man spacewalk to manually grab the spacecraft after attempts using a specially-designed capture bar failed to work. The ship also conducted the first Hubble Space Telescope servicing in 1993, one of the stellar achievements for the space program that installed corrective optics to fix the observatory's flawed vision.

Other trips in the 1990s deployed and retrieved satellites, mapped the Earth with radar and scanned the cosmos with payloads carried in the orbiter's cargo bay. She also visited the Russian space station Mir once.

Then Endeavour opened the International Space Station era by launching the first American piece of the outpost -- the Unity connecting node -- to begin orbital construction in December 1998. Subsequent flights by Endeavour would take up the station's initial solar array power tower, all three sections of Canada's robotics including the arm, mobile transporter and Dextre hands, the Japanese science facility's "attic" and "back porch" for research, and the Tranquility utility room with the Cupola.

This upcoming 12th mission to the International Space Station by Endeavour finishes the American construction efforts, which this ship originally began, by adding the Alpha Magnetic Spectrometer and a final spare parts deck.

Construction of Endeavour started in September 1987 as a replacement vehicle for Challenger. The spaceplane was rolled out of the Palmdale factory in April 1991. She became NASA's fifth and final operational space shuttle with her inaugural launch a year later.

Once retired from service after the STS-134 mission, Endeavour will be safed and readied for museum display.

T-minus 20 minutes and counting. Clocks are running again and headed down to the T-minus 9 minute mark where the next hold is scheduled.

T-minus 20 minutes and holding. Countdown clocks have gone into the planned 10-minute hold. Today's simulated launch remains set for 2:00 p.m. EDT.

Powering space shuttle Endeavour 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 Discovery 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 Endeavour. This powerplant is flying for the 12th time starting with Endeavour's STS-89 to Mir and most recently on Discovery's STS-131.

Commander Mark Kelly is simulating pressurization of the gaseous nitrogen system for Endeavour's Orbital Maneuvering System engines while pilot Greg Johnson goes through the steps to activate the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

Another check of the weather shows current conditions remain "go" across the board. Forecasters predict no chance of any launch weather rule violations today.

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 Endeavour are a mixture of refurbished and brand new hardware. The upper cylinder on the left booster, for example, flew on the third shuttle mission in 1983. And another cylinder on the left-hand booster is flying for the very first time. And there's even a section from Endeavour's maiden launch in 1992 that's now flying on the ship's final voyage.

In all, Endeavour's twin boosters have reused segments and pieces that trace back to 59 previous shuttle launches and 11 ground test-firings.

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

T-minus 1 hour and counting. The Terminal Countdown Demonstration Test rolls onward to the planned 2 p.m. EDT simulated launch time for space shuttle Endeavour. There's still a pair of built-in holds coming up at T-minus 20 and T-minus 9 minutes.

The orbiter closeout crew has finished the hatch closure test and reopened it.

With all of the astronauts inside the spacecraft, the launch pad crew is shutting the crew module hatch to run through those procedures for practice.

Communications checks with the astronauts are being completed with the the Complex 39 launch control center at the Florida spaceport and CAPCOM Butch Wilmore with the ascent flight control team in Houston.

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.)

The final Endeavour astronaut has boarded the shuttle today. Roberto Vittori just entered the hatch to sit on the flight deck's aft-center seat as mission specialist No. 2 and flight engineer.

The European Space Agency astronaut representing Italy holds master degrees in aeronautical sciences from the University of Naples and physics from the University of Perugia. He is a colonel in the Italian Air Force with nearly 2,500 hours in over 40 different aircraft.

He has visited the International Space Station twice aboard Russian Soyuz spacecraft in 2002 and 2005.

Read his NASA biography here.

Now passing the T-minus 2 hour mark in the countdown. A pair of 10-minute built-in holds are planned at T-minus 20 minutes and T-minus 9 minutes, leading toward the 2:00 p.m. T-0 time.

Air Force Col. Mike Fincke is poised to break the U.S. space endurance record during Endeavour's flight by eclipsing the current 377-day cumulative mark held by Peggy Whitson.

But after spending two tours of duty on the International Space Station using Russian Soyuz capsules for transportion, Fincke is ingressing the flight deck's aft-right seat for his very first space shuttle voyage as Endeavour's mission specialist No. 1 and spacewalker.

The native of Pittsburgh holds master degrees in aeronautics and astronautics from Stanford and planetary geology from the University of Houston. In the Air Force, he was a test engineer and logged 1,000 flight hours in more than 30 different aircraft.

His first trip to the space station came in 2004 as the flight engineer on Expedition 9 and he followed that with the 2009 mission as commander of Expedition 18, accumulating 366 days of spaceflight and six Russian-based spacewalks.

Read his NASA biography here.

Previous long-duration resident of the International Space Station, Greg Chamitoff, serves as Endeavour's mission specialist No. 4 and another of the spacewalkers on the flight. He just entered the orbiter's hatch to take the right-hand seat on the middeck.

Born in Montreal, Canada, he earned degrees from CalPoly and Caltech and has a Ph.D. in aeronautics and astronautics from MIT.

His station voyage as part of a flight engineer and science officer on the Expedition 17 and 18 crews in 2008 started by launching on Discovery's STS-124 mission and returning to Earth some 183 days later on Endeavour's STS-126 flight.

Read his NASA biography here.

Endeavour pilot Greg Johnson is making his way to the flight deck's front-right seat right now for his second spaceflight aboard this particular spacecraft.

The retired Air Force colonel has combat experience from Operation Desert Storm and Operation Southern Watch, plus flight test credentials and over 4,000 flight hours in more than 40 different aircraft.

He arrived at NASA in 1998 and flew on the Endeavour mission in 2008 that delivered Japan's first module and constructed Canada's Dextre handyman robot.

Read his NASA biography here.

Drew Feustel went to the Hubble Space Telescope on his previous spaceflight in 2009 and conducted three spacewalks are part of rejuvenating the observatory one last time.

For this shuttle flight to the International Space Station, Feustel will be mission specialist No. 3, the lead spacewalker and ride uphill in the middeck's left-hand seat.

Raised in Lake Orion, Michigan, he earned a Ph.D. in geological sciences from Queen's University in Ontario, Canada, and worked as a geophysicist for Exxon Mobil before becoming an astronaut.

Read his NASA biography here.

Commander Mark Kelly is the first astronaut to board the shuttle today, taking the forward-left seat on the flight deck.

The 47-year-old Navy captain from Orange, New Jersey, has 5,000 flight hours in more than 50 different aircraft and logged over 375 carrier landings, plus performed 39 combat missions in Operation Desert Storm.

A veteran of three previous space shuttle missions, Kelly initially flew as pilot on the STS-108 logistics servicing to the International Space Station in 2001 and Discovery's STS-121 test flight in 2006. His first command came in 2008 as Discovery's skipper on STS-124 that launched the Japanese laboratory module to the space station.

Read his NASA biography here.

And now the crew is up at the 195-foot-level of the launch pad's fixed service structure.

The astronauts have arrived at launch pad 39A to start entering the space shuttle Endeavour. After getting off the Astrovan, the crew took an elevator up to the 195-foot-level of the tower to reach the orbiter access arm that swings over to Endeavour's hatch.

There goes the astronauts! Space shuttle Endeavour's six veteran astronauts just drove by the Press Site on their way from Kennedy Space Center's crew quarters building to the launch pad in the shiny silver Astrovan.

HERE COMES THE CREW. Space shuttle Endeavour's six veteran astronauts have departed Kennedy Space Center's crew quarters building for this morning's countdown dress rehearsal.

Commander Mark Kelly, pilot Greg Johnson, flight engineer Roberto Vittori and spacewalkers Drew Feustel, Mike Fincke and Greg Chamitoff are heading to launch pad 39A where they will climb aboard the orbiter today.

T-minus 3 hours and counting. Clocks have resumed ticking for the Terminal Countdown Demonstration Test, still targeting a 2:00 p.m. EDT pretend liftoff time for Endeavour today.

The weather is absolutely perfect today for a space shuttle launch. All the rain and storms have moved away, leaving blue skies over Central Florida. In fact, the shuttle weather officer gives a 100 percent chance of acceptable conditions for the 2 p.m. EDT pretend liftoff time.

(Yes, the weather team plays along with this dress rehearsal too).

The launch time outlook calls for good visibility, just a few clouds at 3,000 feet, northwesterly winds of 13 peaking to 20 knots and a temperature of 70 degrees.

T-minus 3 hours and holding. The countdown is nearing the end of this scheduled built-in hold. On the real shuttle launch day, fueling of Endeavour will be long finished by this point in the count.

But following through with the sequence for this morning's dress rehearsal, the orbiter closeout crew is working pad 39A to ready Endeavour for the astronauts' arrival.

Randy Bresnik, a previous shuttle flier and a member of the closeout team today, has been busy inside Endeavour cockpit's configuring switches and verifying systems with the launch control center. The closeout team will assist the astronauts getting strapped into their seats just like launch day.

The day lacks the buzz of excitement in the air that real space shuttle launch mornings have at Kennedy Space Center. Nonetheless, the launch team is on station in Firing Room 4 of the Launch Control Center as the abbreviated one-day countdown sequence enters the final five hours for Endeavour this morning.

The astronauts were awakened in their quarters earlier this morning to have breakfast and begin donning their day-glow orange partial pressure spacesuits worn during the ascent and entry phases of a shuttle mission. We'll expect to see the crew emerge around 10:45 a.m. and then head for the launch pad in the Astrovan.

All activities remain on track for the simulated launch time of 2 p.m.

It's practice launch day for the shuttle Endeavour, her six-man astronaut crew and the various ground teams supporting the spacecraft's ascent to orbit. Even the news media joins in the action by photographing the astronauts departing their quarters and following along with the countdown today. Stay with us for live updates throughout the day as the dress rehearsal targets a mock liftoff time of 2 p.m. EDT (1800 GMT).

T-minus 3 hours and holding. The countdown schedule has been revised again. NASA now plans to target 2 p.m. EDT (1800 GMT) for the simulated liftoff time for Endeavour today.

The persistent weather plaguing Florida throughout the day has forced a five-hour delay in the practice countdown timeline for Friday, officials have decided.

The stormy conditions prevented workers from completing preparations on schedule today at launch pad 39A, prompting a ripple effect on the pretend liftoff time tomorrow. Instead of shooting for 11 a.m., the clocks will target a 4 p.m. EDT (2000 GMT) launch for the countdown dress rehearsal.

So departure of the astronauts from their quarters now will occur at 12:45 p.m., arriving at the pad just after 1 p.m. to begin boarding the orbiter.

NASA says managers will meet in the morning to assess how work progresses overnight and decide if any further schedule adjustments are necessary.

The program-level flight readiness review for space shuttle Endeavour occurred today and gave unanimous approval to press ahead toward the agency-level review on April 8. It will be that meeting next Friday which sets the official launch date for the mission.

For now, the April 19 target launch date still looks good.

Countdown clocks around Complex 39 are ticking for Friday's dress rehearsal by the space shuttle Endeavour astronauts to culminate the week's exercises at Kennedy Space Center.

"The vehicle is great shape. We were out there yesterday. We did what's called payload bay walkdown, which is pretty interesting because the vehicle is now in the vertical," commander Mark Kelly told reporters in an informal briefing this morning.

The Terminal Countdown Demonstration Test underway at the Florida spaceport is putting the crew through emergency procedure drills and given Kelly and pilot Greg Johnson some time to practice landing approaches in the Shuttle Training Aircraft.

The stormy weather, however, is interrupting today's scheduled activities to tour the launch pad's escape baskets on the tower and the bunker area.

"The weather today is going to change our plans for training at the pad. Typically we do some egress and fire fighting kind of training. We're going to move some of that to tomorrow, maybe even some of it into launch week for a couple of our crew members," Kelly said.

TCDT is building toward the simulated launch day that occurs Friday for a mock 11 a.m. liftoff time. We will provide live updates throughout the morning right here on this page as the crew heads for the launch pad and gets strapped aboard Endeavour for the final three hours of the countdown.

Check out a picture of the stormy skies over Kennedy Space Center this morning.

Given the stormy weather around Central Florida, this morning's reporter chat with Endeavour's astronauts has changed venues. Instead of occurring at the launch pad, the event will be held inside the auditorium at Kennedy Space Center's Press Site beginning around 8:30 a.m. EDT. We'll have live streaming video coverage right here on this page.

Space shuttle Endeavour's astronauts Wednesday took turns test-driving an armored tank around Complex 39 as part of their emergency training exercises in the Terminal Countdown Demonstration Test.

Read our full story.

The six astronauts to fly Endeavour's final orbital voyage have jetted into the Kennedy Space Center for this week's countdown dress rehearsal with the space shuttle launch team.

Read our full story.

Commander Mark Kelly and mission specialist Mike Fincke have touched down in their T-38 training jet. So all the astronauts have arrived for their Terminal Countdown Demonstration Test at the Florida spaceport. Live video of the crew's comments is coming up.

And check back in a little while for a story and some photos.

Shuttle launch director Mike Leinbach and Endeavour flow director Dana Hutcherson are on hand to greet the astronauts.

The final T-38 should be arriving in a few minutes.

Lead spacewalker Drew Feustel is here now aboard a T-38 being flown by another astronaut not actually on the Endeavour crew.

Endeavour pilot Greg Johnson and mission flight engineer Roberto Vittori are taxiing off the runway now.

The first T-38 jet carrying Greg Chamitoff has landed here at KSC. Piloting his plane is Barry Wilmore.

Good day from the Shuttle Landing Facility where reporters and photographers have gathered to cover the astronauts' arrival.

Endeavour's crew is traveling from Ellington Field outside Houston's Johnson Space Center for today's trip over to Florida's Kennedy Space Center. Arrival out at the Shuttle Landing Facility runway is anticipated beginning around 5:10 p.m. EDT.

The astronauts are traveling in four T-38 jets:

Tail number 924: Commander Mark Kelly and mission specialist Mike Fincke

Tail number 921: Pilot Greg Johnson and mission specialist Roberto Vittori

Tail number 955: Mission specialist Drew Feustel (with non-crew astronaut pilot)

Tail number 962: Mission specialist Greg Chamitoff (with non-crew astronaut pilot)

The space shuttle astronauts are running ahead of schedule this afternoon. NASA says arrival is expected about 5:15 p.m. EDT now.

Space shuttle Endeavour's astronauts will be welcomed to the Kennedy Space Center this evening to begin the Terminal Countdown Demonstration Test activities. TCDT week includes emergency training drills and a launch day dress rehearsal for the crew.

Arrival at the spaceport runway is expected around 7 p.m. EDT. We'll provide live streaming video of the event, which should feature some comments by commander Mark Kelly and potentially other members of the crew as well.

Out at launch pad 39A, meantime, technicians have begun the lengthy work to close out Endeavour's aft engine compartment for flight. Mating of the umbilical unit used for servicing the ship's electricity-producing fuel cells during the countdown is being performed today, too. And the interface verification testing with the mission payloads now inside the cargo bay is ongoing.

Inside launch pad 39A's cleanroom today, technicians completed inserting a $2 billion physics instrument and a pallet of spare parts into the payload bay of shuttle Endeavour for hauling to the International Space Station.

Read our full story.

A few weeks after managers rejected a similar plan during the last shuttle flight, NASA officials hope extra lead time and better planning will permit a three-man Russian Soyuz capsule to undock from the space station and collect never-before-seen imagery of the shuttle Endeavour and orbiting lab linked together.

Read our full story.

The traditional pre-flight media briefings for reporters to learn about Endeavour's mission, understand the payloads being carried and meet with the astronaut crew occurred in Houston today.

Shuttle program manager John Shannon says everything remains on schedule for blastoff April 19.

"I haven't talked to most of you since the outstanding 133 mission earlier this month where we completed the ISS and accomplished more than 100 percent of our mission objectives. So that was an outstanding set of work by the entire team and we're just rolling along here to finish out the program strong like I asked the team to do.

"Processing is going very well for STS-134. Of course Endeavour is out at the pad all stacked up. We've had an extremely smooth flow with the vehicle. The payload arrived at the pad on Monday, we opened up the payload bay doors yesterday, took all of our optical measurements, going through the normal processing today and we anticipate installing the payload tomorrow. Everything is looking extremely good for an April 19 launch."

One potential conflict being talked about, however, is scheduled Russian spacecraft traffic at the International Space Station. Manifests call for the Progress 41P resupply ship to depart on April 26, the fresh Progress 42P freighter to launch from Baikonur Cosmodrome on April 27 and the automated linkup to happen April 29.

But conducting those undocking and docking events while Endeavour is parked at the space station isn't something NASA wants to do. Options include delaying the new Progress cargo ship's launch or launching it on-time and then loitering in orbit until after the shuttle leaves the station.

"We are still in discussions with our Russian partners about that. We have a couple plans. Some of the difficulties is there's a payload in the Progress that has a short timeframe. So the Russians are very interested in the time from when they initiate that payload, load it onto the Progress and then get it onboard ISS. So we're still working through the details about that," said Kirk Shireman, the space station's deputy program manager.

NASA currently considers April 19 through April 22 as viable launch dates for Endeavour. If the launch doesn't go during that period for some reason, Endeavour could wait on the pad to give the Progress a shot, then NASA would pick up with additional tries for the shuttle in an opportunity that stretches into early May.

"We have a plan to have the first part of the shuttle window where the shuttle would have priority, then we'd stand down and let the Progress go, and then, of course, we'd have some of that window availability at the end of that for shuttle.

"But all of that is not finalized yet. We're still in negotiations with John (Shannon) and the shuttle program and with the Russians. I have no doubt we'll work this out. It's just with all the traffic coming and going to ISS these days and all the constraints, we all need to sit down and work through this, and we're doing that."

Asked whether the shuttle might give up April 19 and just delay its launch a week-and-a-half while waiting for the Russian traffic to clear, Shannon said that's not being considered right now.

"We're targeting for the 19th and we haven't done anything to say we're not going to fly on the 19th."

The Russians send up a half-dozen unmanned Progress spacecraft each year to deliver food, oxygen, equipment, experiments and rocket fuel to the space station. Before undocking from the station, the crews fill the ships with trash to burn up in the atmosphere.

The launch pad's mobile gantry, with the mission payloads safely tucked inside its cleanroom, was rotated to enclose space shuttle Endeavour this morning. The orbiter's payload bay doors will be opened today in preparation for Friday's planned installation of the Alpha Magnetic Spectrometer and supply carrier.

The gantry will remain around Endeavour from now until 11 p.m. the night before launch when it retracts to reveal the shuttle for the final countdown.

AMS and ELC No. 3 were offloaded from the transport canister to the ground handling mechanism inside the pad gantry today.

The canister is scheduled to be lowered out of the launch pad at midnight, driven away at 1:30 a.m. and the rotating service structure moved at 5:15 a.m. EDT to enclose Endeavour once again.

The cosmic experiment headed for the International Space Station to probe the mysteries of physics and more spare parts to keep the outpost flying after the space shuttles are retired have arrived at the pad for launch aboard Endeavour four weeks from today.

Read our full story.

The transporter shaped like the shuttle's 60-foot-long payload bay and possessing the Alpha Magnetic Spectrometer and the Express Logistics Carrier No. 3 was hoisted into launch pad 39A overnight as planned.

Work to unload the payloads onto the handling mechanism inside the pad's cleanroom is underway today and the canister should be lowered away tonight, allowing the service tower to roll back around Endeavour early tomorrow morning.

Once all of that is completed, the orbiter's payload bay doors can be opened and these final pieces of the space station will be tucked inside Endeavour for launch.

The special transport canister holding the 30,000 pounds of payloads for shuttle Endeavour has climbed up the ramp to the pad surface and over to the gantry. Technicians plan to start the canister lifting operations after 10 p.m.

NASA will hold an early morning media event at the launch pad for reporters and photographers. Check back tomorrow for a full story on Endeavour's payloads and more pictures.

The payload convoy is entering through the launch pad's perimeter gate now.

The payload's drive to launch pad 39A is underway right now. The canister should reach the complex in a couple of hours, then get lifted into the gantry overnight.

The rotating service structure at pad 39A was retracted away from space shuttle Endeavour this morning in preparation for arrival of the payloads later tonight.

The gantry features a payload changeout room and the equipment to insert the mission hardware into Endeavour's cargo bay. After the payload canister reaches the pad around 8:30 p.m. EDT, it will be hoisted into the tower overnight and the contents unloaded into the cleanroom tomorrow. The canister then lowers away and the gantry placed back around the orbiter to transfer the payloads to Endeavour.

The payload transporter left the Space Station Processing Facility last week and was taken to the special building where today it was turned vertically to stand upright. The journey to pad 39A begins with the team reporting for duty this evening at 6 p.m.

Hazardous fuel loading operations were conducted Friday and Saturday on space shuttle Endeavour as technicians loaded the orbiter's forward and act reaction control system thruster tanks and the left and right orbital maneuvering system engine pods with storable fuel and oxidizer. The orbiter's auxiliary power units were serviced as well.

The launch pad has been reopened for normal work in preparation for retracting the gantry-like rotating service structure on Monday to welcome the mission's payloads. The Alpha Magnetic Spectrometer and Express Logistics Carrier No. 3 were installed into the transportation canister at Kennedy Space Center's Space Station Processing Facility last Tuesday and Wednesday. The can was turned upright and will head for pad 39A on Monday night for hoisting into the payload cleanroom.

Check out this photo gallery showing the payloads being readied for meeting up with Endeavour at the launch pad.

The space shuttle Endeavour is one-week into her final launch pad processing campaign for the planned April 19 blastoff. Since rolling to the seaside complex last Thursday night, work immediately began to hook up the spacecraft and the mobile platform with the ground systems at pad 39A and validate the connectivity.

A confidence run of the orbiter's three auxiliary power units occurred Friday evening. The units, located in the aft compartment of Endeavour, provide the pressure needed to power the hydraulics of the shuttle during the launch and landing phases of the mission for such events as moving the aerosurfaces, gimbaling the main engine nozzles and deploying the landing gear.

After the APU hot-fire was completed, the rotating service gantry was moved around Endeavour on Saturday morning.

The gaseous hydrogen vent arm and its ground umbilical carrier plate have been mated to the backside of the external tank as well. Leak checks were conducted successfully, too.

A flight readiness test of the three main engines, pre-launch positioning of the nozzles and a leak check of the main propulsion system using helium were the among the activities performed this week. And preps have been underway for the pre-launch propellant servicing for the orbiter's maneuvering engines and control thrusters, plus the SRB steering system.

Meanwhile, check out our updated launch windows chart and the latest mission timeline.

A United Space Alliance worker at launch complex 39A, where the shuttle Endeavour is being processed for launch April 19, fell to his death early Monday, a NASA spokesman said. An investigation is underway and all work at the pad has been suspended for the rest of the day.

Read our full story.

A statement from NASA:

"At about 7:40 a.m. EDT this morning, a United Space Alliance worker fell at NASA Kennedy Space Center's launch pad 39A. NASA emergency medical personnel responded, but they were unable to revive the man. Because of medical privacy, currently we're not able to release any additional details about this fatality. Family members are being notified.

"All work at launch pad 39A has been suspended for the rest of the day, and counseling and other employee assistance are being provided to workers. Right now our focus is on our workers and for the family of the USA employee.

"The incident is under investigation."


Read our earlier status center coverage.