Read our full story.

Read our full story.

The EVA lasted 7 hours and 20 minutes. This was the first of five planned spacewalks during Atlantis' mission.

The excursion brings to 136 hours and 30 minutes the total Hubble Space Telescope servicing spacewalk time accumulated over five missions and 19 EVAs. A chart showing the preview spacewalks can be viewed here.

Read our full story.

Read about that launch here.

A failure in the SIC&DH system aboard the telescope last September forced NASA to scrap Atlantis' original October launch plans. The shuttle was perched atop the pad, but the extended delay resulted in Atlantis being rolled back to the hangar while two subsequent flights to the international space station proceeded.

Although only half of the system failed and controllers successfully switched the telescope to the backup side, it left Hubble with no redundancy. NASA opted to add this replacement job to the servicing mission to restore the backup system. The unit is vital in routing commands to Hubble's instruments and sending the science data back to Earth.

During the past half-year, technicians have prepared a spare data handling unit to be flown aboard Atlantis and mounted in the telescope.

Read our full story.

Next up in the spacewalk will be removal and replacement of the telescope's partially failed science instrument command and data handling unit.

The spacewalkers are about to move the old WFPC2 camera from its temporary stowage bracket on the side of the payload bay to the carrier box where WFC3 rode to orbit.

A backgrounder fact sheet on the camera and its scientific objectives can be downloaded here.

Read our full story.

A feature story from NASA about the science legacy of WFPC2 can be read here.

Astronauts John Grunsfeld and Drew Feustel switched their suits from shuttle-provided power to internal batteries at 8:52 a.m. EDT, marking the start of this planned 6 1/2-hour EVA.

Read our full story.

However, there is one row of 16 tiles around the thrusters on the nose of Atlantis that wasn't sufficiently covered in yesterday's scans. The robot arm camera can look at those tiles quickly later.

Read our full story.

Cain also said in this afternoon's news conference that sensors on the shuttle have indicated a small space debris or micrometeoroid debris impact on the right wing. However, the data says the impact -- measured at less than 0.5 G's -- was not hard enough to cause any worrisome damage. The heat shield is scheduled to be inspected for such space hits before landing.

In about an hour, the astronauts will gather together to review procedures for tomorrow's spacewalk. They will go to sleep at 8:31 p.m. EDT, then awaken at 4:31 a.m. to begin final preps for the first EVA of the mission.

Read our full story.

Basically the workbench for Hubble, the platform features a Lazy Susan-like ring that the telescope actually sits on, allowing the observatory to be rotated and pivoted as needed to provide the best available access to various worksites for spacewalkers during the mission.

The hardware has flown on the previous Hubble servicing flights, as well as the first ever satellite repair mission aboard Challenger in 1984 that fixed the Solar Max spacecraft.

Speeding along at five miles a second, some 350 miles above Western Australia, the shuttle's robotic arm reached out and captured the 12 1/2-ton, 43-foot tall observatory.

Robot arm operator Megan McArthur will now maneuver Hubble into the payload bay of Atlantis and mount the telescope to a Lazy Susan-type service platform where it will reside for the servicing work.

Scott Altman will fly Atlantis to within 35 feet of the telescope and hold position while Megan McArthur, using a view from a camera mounted at the end of the robotic arm to gauge alignment, latches onto the telescope.

Using views from a camera centered in the ring where the telescope will be berthed in the shuttle bay, McArthur will then lower Hubble into a special cradle, called the Hubble Space Telescope Flight Support System, in Atlantis' payload bay. The telescope will be latched to the FSS for the duration of the servicing work.

The Lazy Susan-type service platform can be rotated and pivoted as needed to provide the best available access to various worksites for the spacewalkers.

Once on the FSS, an umbilical from Atlantis will be remotely connected to Hubble to provide transmission of electrical power from the shuttle to the telescope. Then, Altman will maneuver the shuttle to allow Hubble's solar arrays to track the sun, fully charging the telescope's batteries.

The crew and ground controllers are assessing a possible problem with equipment used to establish a communications link between Atlantis and Hubble. The astronauts have been asked to check connections and wires on the box before possibly switching to the backup side of the system.

Read our full story.

Meanwhile, Hubble's ground controllers continue to work through a list of planned commands to prepare the telescope for Atlantis' arrival. Overnight, the two high gain antennas were successfully stowed. A little later this morning, the two power-generating solar arrays will be slewed, or positioned, edge-on in relation to the shuttle's path to protect them from any thruster plumes.

A video preview of today's rendezvous can be watched here.

Read our full story.

Read our full story.

The door will remain closed throughout the servicing mission, then later reopen to let the light of the Universe back into the refurbished and updated telescope.

The closing of the door, which was confirmed at 6:24 p.m. EDT, is one of the key events before the shuttle visit begins. Retraction of the high gain communications antennas on Hubble is scheduled for overnight at 1:46 a.m. EDT.

Atlantis just completed an engine firing, keeping the shuttle on course for tomorrow's rendezvous. Commander Scott Altman will fly the shuttle within reach of the spacecraft, allowing astronaut Megan McArthur, operating the shuttle's 50-foot robot arm, to grapple Hubble at 12:54 p.m. EDT.

Read our full story.

Spaceflight Now+Plus users can see a slow-motion clip of the video.

If you're not yet a subscriber, you can learn more here.

Read our full story.

The damage doesn't seem to be worrisome, the astronauts were told. "At this point, the preliminary assessment is that it doesn't look very serious. Those tiles are pretty thick," CAPCOM Dan Burbank said.

Read our full story.

The left wing inspections are next up in this multi-hour job to survey the shuttle to look for any signs of launch damage. The precautionary safety inspection has become a standard activity for all post-Columbia shuttle crews.

Read our morning story.

Today will be spent inspecting Atlantis for launch damage. Other activities include checking out the spacesuits to be worn during the mission's spacewalks and preparing equipment for tomorrow's arrival at the Hubble Space Telescope.

The shuttle's robot arm has grappled the Orbiter Boom Sensor System (OBSS) and is lifting it out of the payload bay as the crew prepares to inspect Atlantis' wing leading edge, nose cap and belly tiles of the thermal protection system for any launch damage.

At present, Atlantis is 8,000 miles behind the Hubble Space Telescope. The shuttle is flying in an elliptical orbit en route to catch the observatory that's orbiting 350 miles high.

The astronauts are scheduled to begin an 8-hour sleep period at 9:01 p.m. EDT.

Read our full story.

"At this point, there's absolutely no imagery observations indicating any concern at all," the CAPCOM just radioed the shuttle crew from Mission Control.

"That's outstanding, Houston. Thanks for that early word," commander Scott Altman replied.

Two very minor issues seen during today's launch are being recapped by Mission Management Team chairman Mike Moses at the post-launch news conference. One of four redundant systems in powering the flight control aerosurfaces had a problem and a faulty sensor on one of the main engines rang an alarm onboard the shuttle a couple of times. Neither issue caused any trouble during the launch, Moses said.

Read our launch story.

After the eight-and-a-half-minute climb to space, Atlantis achieved a suborbital trajectory with a high point of 334 miles and low point of 33 miles. A firing of the twin orbital maneuvering system engines on the tail of Atlantis will raise the orbit to 342 by 125 miles, inclined 28.5 degrees to the equator.

The shuttle astronauts will conduct five straight days of spacewalks to install a pair of new scientific instruments into Hubble, attempt ambitious repairs on two failed instruments, replace the observatory's original 19-year-old batteries, plus exchange other internal components.

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.

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.

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.

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 Greg Johnson 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.

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.

Over the course of the next minute, the orbiter's heaters will be configured for launch by commander Scott Altman, 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.

"It's a great day to go fly," Leinbach told commander Scott Altman.

After the eight-and-a-half-minute climb to space, Atlantis should achieve a suborbital trajectory with a high point of 334 miles and low point of 33 miles. A firing of the twin orbital maneuvering system engines on the tail of Atlantis about 30 minutes later will raise the orbit to 342 by 125 miles, inclined 28.5 degrees to the equator.

"We think from what we're can tell so far we're probably 'go,'" NASA commentator George Diller says. "But we have to be able to prove it. So that's why we're waiting for them to get back and we can see the pictures they've taken and see their data."

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.

Also, the primary avionics software system (PASS) is transferring to Atlantis' BFS computer so both systems can be synched with the same data. In case of a PASS computer system failure, the BFS computer will take over control of the shuttle vehicle during flight.

Commander Scott Altman has pressurizing the gaseous nitrogen system for Atlantis' Orbital Maneuvering System engines, and pilot Greg Johnson has activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water boilers.

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.

A short time ago, the Ground Launch Sequencer mainline activation was completed. The GLS program will control the final 9 minutes of the countdown.

After retrieving the twin SRBs, the ships will tow the boosters back to the Cape for a planned Wednesday morning arrival.

You can watch the live video from the Kennedy Space Center on the right-hand side of this page.

The pre-flight alignment of Atlantis' inertial measurement units is now beginning, and will be completed by the T-minus 20 minute mark. The IMUs were calibrated over the past few hours of the countdown. The three units are used by the onboard navigation systems to determine the position of the orbiter in flight.

Meanwhile, the S-band antennas at the MILA tracking station here at the Cape are shifting from low power to high power. The site will provide voice, data and telemetry relay between Atlantis and Mission Control during the first few minutes of flight. Coverage then is handed to a NASA Tracking and Data Relay Satellite in space.

The countdown is proceeding smoothly with no significant technical issues. The weather predictions still call for good conditions here at Kennedy Space Center. The only concern is the chance of rain showers at the emergency landing site in Spain.

At this point in the count, the Ground Launch Sequencer software that will control the final nine minutes of the countdown has been initialized. Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first stage of flight.

The 37-year-old oceanographer from California is a space rookie. She will operate the shuttle's robotic arm to capture Hubble, move the spacewalkers around during the EVAs and then redeploy the upgraded the telescope.

Read her biography here.

He will ride into space for the first time of his career in the flight deck's aft-right seat.

Read his biography here.

Massimino is climbing to the center seat on the middeck now.

Read his biography here.

You can watch the live video from the Kennedy Space Center on the right-hand side of this page.

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

Read Johnson's biography here.

Read his biography here.

Feustel just crawled through Atlantis' hatch to take the right-hand seat on the middeck.

Read his biography here.

You can watch the live video from the Kennedy Space Center on the right-hand side of this page.

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

Read Altman's biography here.

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

You can watch the live video from the Kennedy Space Center on the right-hand side of this page.

The AstroVan convoy will stop at the Launch Control Center for some members of NASA management and astronaut Steve Lindsey to exit the Astrovan. The managers will take their positions in the Firing Room while Lindsey heads over to the Shuttle Landing Facility to begin weather reconnaissance flights in a T-38 jet. He will later switch to the modified Gulfstream jet, which is known as the Shuttle Training Aircraft because its flying characteristics are very similar to the space shuttle.

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.)

The Final Inspection Team has completed its work and departed launch pad 39A. NASA says the team didn't find any areas of concern.

A short time ago, commander Scott Altman, pilot Greg Johnson and flight engineer Megan McArthur received a weather briefing on conditions at the Kennedy Space Center and at the Spanish abort landing site.

The team is responsible for checking the shuttle and launch pad one last time prior to liftoff. The team is comprised of engineers and safety officials from NASA, United Space Alliance and tank-builder Lockheed Martin. At the conclusion of their two-hour tour-of-duty, the team will have walked up and down the entire fixed service structure and mobile launcher platform.

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

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

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

Immediately below the video screen, click on the "Chat" button to join today's interactive coverage.

Recent activities in the countdown have included pre-flight calibrations of Atlantis' inertial measurement units, aligning antennas with the launch pad from the Ponce de Leon and MILA tracking stations and communications checks with the Eastern Range.

The outlook includes a few low-level cumulus clouds and scattered high cirrus at 25,000 feet, 7 miles of visibility, southeasterly winds from 120 degrees at 8 peaking to 13 knots and a temperature of 82 degrees F.

"Dry conditions continue over Central Florida. Today the high pressure ridge responsible for KSC summer weather pattern will begin to gradually migrate to the south, keeping the east coast sea breeze nearer the coastal area. Cumulus clouds and showers developing along the sea breeze will likely be slow to build however, allowing favorable conditions for launch. Still, our primary concern for launch is cumulus clouds developing early along the sea breeze," Air Force meteorologists reported this morning.

But if the launch is delayed to the backup opportunities on either Tuesday or Wednesday, the odds of good weather drop to 60 percent.

"Weather looks less favorable on Tuesday due to a front moving into the area which increases moisture and instability, as well as creating a chance for isolated thunderstorms, some of which may be strong. On Wednesday the front is forecast to slowly migrate back to the north, causing stronger easterly winds and raising concerns for crosswinds at the Shuttle Landing Facility (SLF), a low cloud ceiling over the area, and showers within 20 nautical miles."

But given the cryogenic nature of the oxidizer and propellant, the supplies naturally boil away. So the tanks are continuously topped off until the final minutes of the countdown in a procedure called "stable replenishment."

Now that the hazardous tanking operation has been completed, the Orbiter Closeout Crew and Final Inspection Team will head out 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.

The fueling takes about three hours to complete, and keeping the tank fully loaded continues until just minutes before liftoff time.

The process starts with the chilldown thermal conditioning of the system, followed by a slow-fill mode and then the fast-fill mode. The tank then enters a stable replenishment mode that ensures the liquid hydrogen and liquid oxygen supplies are topped off through the final minutes of the countdown.

The cryogenics are pumped 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.

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.

Launch morning begins with a 5:30 a.m. wakeup call, followed by medical checks at 6 a.m. and breakfast at 6:30 a.m. They'll begin suiting up a little after 9:30 a.m. and depart crew quarters for the launch pad at 10:16 a.m. to begin boarding Atlantis a half-hour later.

Atlantis' crew module hatch is scheduled to be closed for launch around 12 noon.

The crew spent a relaxed Sunday getting ready for flight. The commander and pilot flew the Shuttle Training Aircraft to practice landing approaches at the Kennedy Space Center runway, then the entire crew went to launch pad 39A for a final pre-flight tour and later traveled to the astronauts' "beach house" to visit with family members. Status briefings on the space shuttle, payloads and weather occurred late in the afternoon, and the crew went to sleep at 9 p.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.)

The Mission Management Team met earlier this hour and gave the "go" to begin fueling the shuttle. Engineers in Firing Room 4 started the three-hour process as planned.

The coundown has just resumed ticking after the two-hour planned hold at the T-minus 6 hour mark. The next scheduled hold occurs at T-minus 3 hours.

Liftoff remains targeted for 2:01 p.m. EDT.