BY SPACEFLIGHT NOW

Follow the progress of the Expedition Two crew's stay aboard the international space station as well as the STS-100 flight of space shuttle Endeavour. Reload this page for the very latest.

THURSDAY, APRIL 26, 2001
2348 GMT (7:48 p.m. EDT)

Revising an earlier decision to extend the shuttle Endeavour's flight by one day, NASA managers late today decided to extend the mission at least two days to give engineers more time to resolve ongoing computer problems hobbling the international outpost.

The plan, if agreed to by the Russians, would delay launch of a Soyuz spacecraft carrying millionaire space tourist Dennis Tito by at least one day and possibly longer.

"For folks who like to fly in space, I think I have what is good news for the Endeavour crew," astronaut Cady Coleman radioed from Houston shortly after 7 p.m. "We are going to stay docked another day, that would be two total, and plan on undocking on flight day 12 (Monday) and landing on flight day 14 (Wednesday).

"That gives us some time to get our arms around our computer situation and really get a good look at what's going on before we decide to do MPLM and SLP ops," she told station astronaut Susan Helms and shuttle flier Chris Hadfield.

Coleman was referring to delayed work to move a cargo module from the station to the shuttle's payload bay for return to Earth and additional work with the station's newly installed robot arm to hand a no-longer-needed cargo pallet to Endeavour's robot arm for reberthing in the ship's cargo bay.

"Our plan presently is if we can get comfortable tomorrow we would do MPLM (cargo module) ops and the soonest we would do SSRMS (station arm) ops with the SLP (Spacelab Pallet) would be the next day after that," Coleman said.

"Well, Chris is pretty happy," Helms replied. "And Alpha's pretty happy."

"Well I should actually couch that with words that we are pending Russian concurrence, they would have to move their Soyuz launch," Coleman said. "And so we're looking for that concurrence and folks are working real hard to make sure everything is coordinated. But right now that's our plan."

Tito and his two cosmonaut crewmates are scheduled for launch Saturday from the Baikonur Cosmodrome. It takes two days for a Soyuz to catch up with its target and docking was expected Monday morning.

But under the current plan, Endeavour will not leave the station until Monday, which would prevent the Soyuz from making an on-time launch. That's because the Russian spacecraft would have to pass with 20 feet or so of the shuttle's vertical tail fin during final approach and it is not known how that might affect the ship's rendezvous radar, radios or other systems.

2319 GMT (7:19 p.m. EDT)

MISSION EXTENDED AGAIN! Endeavour's stay at the international space station will be extended by two days, officials have just decided. So undocking will now occur on Monday. Just an hour ago managers approved a one-day extension.

This extension will have a ripple effect by delaying the Russian launch of a Soyuz rocket from Baikonur. However, that is still pending Russian concurrence, the station crew was told. It is unclear at the moment what the new launch date will be.

2305 GMT (7:05 p.m. EDT)

NASA's mission management team met late today and decided to extend the shuttle Endeavour's mission by "at least" one day to give engineers additional time to troubleshoot ongoing computer problems aboard the international space station.

Endeavour and its seven-man crew had been scheduled to undock Saturday morning for a landing back at the Kennedy Space Center around 10 a.m. Monday. Undocking now will slip to Sunday at least, giving the station crew just 16 hours or so to prepare for arrival of a Russian Soyuz spacecraft carrying two cosmonauts and U.S. millionaire space tourist Dennis Tito.

As soon as the station's computer system is restored to normal operation, Endeavour's crew will use the shuttle's robot arm to undock the Italian Raffaello cargo module from the station's Unity module and mount it back in the orbiter's payload bay for return to Earth.

Station astronaut Susan Helms then will use the newly installed Canadian-built robot arm to hand a 3,000-pound cargo pallet back to the shuttle's robot arm so it can be returned to Earth.

Helms and crewmate James Voss then will put the arm through a series of delayed tests to make sure the $600 million space crane will be ready to install the station's main airlock during the next shuttle assembly flight in June.

Assuming, of course, that engineers can get the station's computer system back in good health.

"The MMT has met and we have extended the mission at least one more day," astronaut Cady Coleman radioed the shuttle crew from mission control "We do not at this time have a time for you that we're going to perform the MPLM (Raffaello) and SLP (cargo pallet) handoff activities. But as soon as we know that, we'll let you know, hopefully, when you get up in the morning. But if not, we think there are lots of things that you and the two crews can be doing to get the ISS into shape."

"Yeah, Cady, we agree, we've been tagging up and they've got a lot of tasks lined up that we can help them with," replied Endeavour skipper Kent Rominger. "We've got plenty of work to keep us employed up here."

"We copy, we think ISS is in a good config docked to shuttle there, it's a great time to be able tyo understand these kinds of problems and in the meantime, we get to put the ISS crew in much better shape before you leave," Coleman said.

Ground engineers, meanwhile, continue efforts to revive two computers in the Unity module that shut down earlier today. Command and control computer No. 2 in the Destiny laboratory module continues to operate normally. Destiny's other two C&C machines are expected to remain out of action until the Unity computers are revived.

2235 GMT (6:35 p.m. EDT)

MISSION EXTENDED. Mission managers just announced Endeavour will remain docked to the international space station one extra day while troubleshooting continues with the outpost's computer systems. Undocking is now set for Sunday with landing on Tuesday.

2143 GMT (5:43 p.m. EDT)

NASA's Mission Management Team is slated to convene a meeting in about 15 minutes to discuss the option of extending space shuttle Endeavour's stay at the international space station. The shuttle was scheduled to undock on Saturday, but Endeavour does have enough consumables to stay two additional days.

Two major events are left to be accomplished during this shuttle mission -- unberthing the Raffaello cargo module for return to Endeavour's payload bay and the handoff of the Spacelab pallet from Canadarm2 to the shuttle's arm.

Those activities can't be performed until the station's computer troubles are sorted out.

Earlier today officials said extending Endeavour's stay at the station by one day -- with undocking on Sunday -- would not impact plans to launch a fresh Soyuz lifeboat on Saturday with tourist Dennis Tito onboard. However, should Endeavour stay two extra days then the Soyuz launch would slip one day.

It takes the Soyuz about 46 hours to reach the orbiting outpost following liftoff. NASA does not want the capsule to dock while the shuttle is still attached to the station, however, since analyses have never been conducted to ensure it is safe to do so.

2040 GMT (4:40 p.m. EDT)

Two computers in the space station's Unity module unexpectedly shut down today amid ongoing work to recover the use of command computers in the Destiny laboratory module. It was not immediately clear whether this latest computer glitch was the result of work to reconfigure the command computers or whether it represented a fresy problem.

Either way, harried flight controllers decided they needed more time to complete troubleshooting and computer reconfiguration work, telling the astronauts, in effect, to take the rest of the day off.

The crew worked earlier today to finish loading an Italian cargo module with station trash and no-longer-needed equipment so the module could be undocked and reberthed in the shuttle Endeavour's cargo bay.

But the station's main command and control - C&C - computers are needed to unlatch the Raffaello module from its docking port on the Unity module and flight controllers want to make sure the computer system is healthy and fully redudant before proceeding with normal operations.

Depending on how the system behaves overnight, the astronauts could be cleared to remove Raffaello early Friday before pressing ahead with delayed work to checkout the station's new robot arm. But that, too, requires an operational C&C computer system and so far, flight controllers have not given the equipment and its software a clean bill of health.

The two computers in Unity that went off line this afternoon were instrumental in getting one of the C&C computers in the Destiny module back in action overnight. Engineers were in the process of reconfiguring the Unity computers today when they suddenly dropped off line.

1948 GMT (3:48 p.m. EDT)

Mission Control has decided to forego any plans to undock the Raffaello cargo module from the international space station today using Endeavour's robot arm. The computer troubles aboard the station are preventing the supply module from being removed from the berthing mechanism on the Unity connecting node at this point.

The astronauts have packed Raffaello with trash and unneeded equipment for return to Earth. They are ready to close the module's hatch upon the ground's OK, either later today or tomorrow.

1835 GMT (2:35 p.m. EDT)

Flight controllers regained at least partial control of one of the international space station's critical command computers today after a computer in a different part of the station launched an emergency program called "Mighty Mouse" in a last-ditch bid to save the day. Read our latest story.

1645 GMT (12:45 p.m. EDT)

The booster rocket that will carry the Soyuz TM-32 spacecraft and space tourist Dennis Tito into orbit on Saturday was rolled to its launch pad at the Baikonur Cosmodrome at sunrise this morning. Read our full story.

We also have exclusive video from today's rollout. Subscribers of our STS-100 Mission Theater can watch the clip here.

If you aren't yet a subscriber, here is the page with details.

1015 GMT (06:15 a.m. EDT)

After a long night of unsuccessful work on the ground to recover use of the space station's crippled command and control computers, astronaut Susan Helms checked their status using an on-board laptop computer shortly after crew wakeup today and reported one of the machines was, in fact, up and running.

Read the full story.

0225 GMT (10:25 p.m. EDT Wed.)

There has been some progress made tonight in Mission Control's efforts to restore the international space station's main commanding and control computer set.

At 10:10 p.m. EDT flight controllers ordered Command and Control Computer No. 3 off, which brought C&C No. 2 up as the primary unit. That set off alarms aboard the station, waking up the outpost's residents.

The ground is now receiving some telemetry through the system, and astronaut Jim Voss was able to access the network via an onboard laptop computer.

Troubleshooting will continue through the night and officials have told the astronauts to go back to bed since they need "fresh minds" for the work ahead on Thursday.

NASA also reports that following a power cycle of C&C No. 1, the unit completed a diagnostic command sent from the ground to the station just before 8:30 p.m. EDT. The test was to turn on and off a light in the Destiny laboratory module.

See our comprehensive story for a full explanation of this computer trouble.

WEDNESDAY, APRIL 25, 2001

The international space station's three main control computers were crippled today by a subtle and so-far-baffling software glitch that disrupted normal operations, forced the crew to delay critical robot arm tests and triggered a massive troubleshooting effort in Houston. Read our updated full story.

1850 GMT (2:50 p.m. EDT)

The Soyuz spacecraft that will carry Dennis Tito to the international Space Station was attached to its booster rocket today in preparation for Saturday's blastoff. Tito and his Russian and Kazakh crewmates also participated in a traditional flag raising ceremony. Read our full story.

1845 GMT (2:45 p.m. EDT)

Station commander Yuri Usachev reports the Russian Vozdukh carbon dioxide removal system in the station's Zvezda module has resumed working. The system abruptly shutdown earlier today.

1650 GMT (12:50 p.m. EDT)

Still no progress is correcting the computer routing problem aboard the international space station. Further complicating matters is the station's Ku-band high-data rate communications antenna lost track of NASA's orbiting relay satellites during the computer troubleshooting earlier. So now controllers are trying to get the Ku system operational again to restore the downlink of station telemetry.

1556 GMT (11:56 a.m. EDT)

Given the continued computer problems aboard the space station, Mission Control is looking to postpone by 24 hours today's planned Canadarm2 tests and complex maneuver to hand the Spacelab pallet to Endeavour's robot arm. The arm activities can't be performed until one of the onboard command and control computers can get linked up with a mass memory unit, a file server of sorts.

Thursday's timeline had always been set aside to support a third spacewalk had that become necessary for Chris Hadfield and Scott Parazynski. But since another spacewalk isn't needed, NASA can slip the arm tests to Thursday without causing any significant impact to this mission.

1530 GMT (11:30 a.m. EDT)

The handover from one command and control computer to another aboard the international space station has been completed. However, the switch has not resolved the problem the computers are having whereby the link to a file server is dropped for some unknown reason. The computers need to access the server in order for today's testing of Canadarm2 to occur. So ground controllers are continuing to troubleshoot the problem. The robotics tests remain on hold.

Meanwhile, the station's Russian Vozdukh carbon dioxide removal system in the station Zvezda module shut down a short time ago. Troubleshooting is underway with this problem, too.

Last week the system experienced a reduced air flow that appeared to clear itself. While Endeavour is docked to the station the shuttle's carbon dioxide removal systems can handle air purification for both craft. The concern is having the Vozdukh back online before the shuttle leaves Saturday and the subsequent arrival of the Soyuz taxi crew next week. The station does have a limited supply of CO2-absorbing lithium hydroxide canisters. While that's not a problem to use those canisters, flight controllers naturally want to reserve the lithium hydroxide supply for emergency use only.

Aboard the station this morning the astronauts have marched ahead with chores to unpack the Raffaello cargo van and transfer scientific experiments from Endeavour's middeck storage lockers to the station's Destiny laboratory module.

1256 GMT (8:56 a.m. EDT)

Flight controllers have decided to switch over to command and control computer No. 3. This will delay Canadarm2 testing for another two hours or so.

The astronauts, meanwhile, are spending the morning unloading the Raffaello cargo moving van docked to the station.

1239 GMT (8:39 a.m. EDT)

Problems with two command and control computers aboard the international space station have delayed the start of today's robot arm operations. Command and control computer No. 1 shut down last night during crew sleep and C&C 2 is having problems accessing data on the station's file server that is needed for tests of the Canadarm 2 space crane.

Engineers thought they had the problem fixed earlier this morning, but C&C 2 once again ran into problems linking to the file server. A third command and control computer is available and it is in good health. But it would take about 90 minutes to switch over to that machine. Flight controllers are assessing the situation to determine the best course of action. In the meantime, robot arm operations are on hold and the station crew is pressing ahead with work to unload the Raffaello cargo module.

1030 GMT (06:30 a.m. EDT)

The international space station's new robot arm will be put to the test today, maneuvering a 3,000-pound cargo pallet about to make sure it can do the heavy lifting required for subsequent station assembly flights.

The arm was launched unpowered and folded up on a Spacelab Pallet mounted in the shuttle Endeavour's cargo bay. The arm has now been assembled, powered up and attached to the hull of the Destiny laboratory module.

The 57-foot-long crane is made up of two long booms connected at a rotating elbow joint. Each boom is equipped with complex wrist joints and a grappling snare on each end. Either end can be used to anchor the crane or latch on to station components.

After assembly and initial checkout, one end was locked onto the hull of the station's Destiny laboratory module. The other end remains latched onto the Spacelab Pallet that carried it into orbit.

Today, astronaut Susan Helms, operating the Canadarm 2 space crane from a work station inside Destiny, will move the cradle through a series of maneuvers to test the arm's performance with a load on one end. She then will "hand it off" to the shuttle's robot arm, which will berth the pallet back in Endeavour's cargo bay for return to Earth.

The tests today, and additional checkout work Thursday, will clear the way for the next station assembly flight in June - flight 7A - when the Canadarm 2 will be used to install the station's main airlock.

"The arm ... has been tested for years and years in simulation and on the ground," Canadian astronaut Chris Hadfield said in a NASA interview. "But you don't really know until you go do it for real. And we have to use this arm on the flight after ours to assemble the space station. It has to be a trusted, proven piece of hardware by 7A, by the flight after ours.

"So just like any new piece of hardware, you want to move it each direction and shake it a little bit and see that it behaves the way you think. This cradle weighs 3,000 pounds. And so here is a nice, big, heavy mass on the end of the arm and you can do all these tests: Shaking it and moving quickly and stopping and making sure that all the math was right."

Hadfield and astronaut Scott Parazynski installed the crane during two spacewalks Sunday and Tuesday. For today's arm operations, Hadfield will assist Helms during the Canadarm 2 pallet maneuvers, then move back to Endeavour to operate the shuttle's Canadian-built arm for the pallet handoff.

"The Spacelab Pallet weighs on the order of 3,000 pounds, so they'll check out the dynamics features of the arm with a load at the end of it, check out the video systems on board, check out the performance of all of the various capabilities that the arm has to offer," Parazynski said.

"It's a three- or four-hour activity to shake down the arm and then deliver it to a point where the shuttle arm can now pick up the Spacelab Pallet. Chris, who hails from Canada of course, will be doing the honors there. Kind of very nice symbolic thing as well, to be able to, for the very first time, have both Canadarms operational.

"He'll be grabbing the Spacelab Pallet offered up by the space station arm and retrieve that from the station crew. The station will then back away the SSRMS and Chris will then berth the Spacelab Pallet back into the payload bay."

TUESDAY, APRIL 24, 2001

Two spacewalking electricians wired the international space station's new robot arm into the lab's power grid today, completing the $900 million crane system's initial installation after extensive troubleshooting to activate an initially dead backup circuit. Read our full story.

2020 GMT (4:20 p.m. EDT)

Faced with no options, the NASA-led panel that manages the International Space Station granted the Russians an exemption on Tuesday to fly tourist Dennis Tito to the orbital outpost. Read our full story.

2015 GMT (4:15 p.m. EDT)

EVA ENDS. Space shuttle Endeavour's airlock is now being repressurized, officially bringing today's spacewalk by Chris Hadfield and Scott Parazynski to a conclusion at 4:14 p.m. EDT. The EVA lasted seven hours and 40 minutes.

This was the 104th spacewalk in U.S. space program history, the 64th to occur from the space shuttle and 20th dedicated to international space station construction by 21 American astronauts, one Canadian and one Russian. The total spacewalking time dedicated to station assembly has now grown to 138 hours and 50 minutes.

Meanwhile, the station residents have spent the day unloading the Raffaello cargo module docked to the outpost by the shuttle crew yesterday. Hatches between the two spacecraft are due to be opened, uniting crews in about 90 minutes.

2000 GMT (4:00 p.m. EDT)

The spacewalkers have made their way back into Endeavour's airlock. The EVA officials concludes when the airlock repressurization is initiated.

1925 GMT (3:25 p.m. EDT)

The international space station has a spare electronics box mounted to its exterior. The Direct Current Switching Unit is now connected to the External Stowage Platform on the Destiny lab, completing the last major job of today's spacewalk.

The spacewalkers will now beginning cleaning up, putting away their tools, equipment and tethers in preparation for returning to Endeavour's airlock to bring this EVA to a close. The spacewalk is nearing the seven-hour mark, a bit extended due to the extra work required to get the Canadarm2 powered up and the fruitless search for a piece of debris from a broken antenna connector.

1905 GMT (3:05 p.m. EDT)

The Direct Current Switching Unit has been detached from its launch bracket on the side wall of Endeavour's payload bay. Riding on the end of the shuttle's robot arm, Scott Parazynski is carrying the box to its new home on the side of Destiny.

1850 GMT (2:50 p.m. EDT)

With Canadarm2 now parked in a "hover" position, the spacewalkers have been cleared to move the Direct Current Switching Unit from the shuttle's payload bay to the station.

The efforts to retrieve the connector debris have been called off. Hadfield could not find the piece of fastener.

1820 GMT (2:20 p.m. EDT)

Canadarm2, having "switched ends" earlier today, is now slowly moving the Spacelab pallet away from its attachment mechanism on the Destiny lab. The pallet will be left dangling on the end of the arm overnight; the structure is due to be handed off to the shuttle's robot arm tomorrow for return to the payload bay.

Meanwhile, spacewalker Hadfield is still in search of that piece of debris and Parazynski has gone back into Endeavour's airlock to recharge his suit batteries and connection to shuttle-provided oxygen.

1751 GMT (1:51 p.m. EDT)

Spacewalker Chris Hadfield has returned to the starboard berth of the Unity node. This morning while removing a no-longer-needed communications antenna from this area, a connector fastener broke and allowed a piece of debris to float behind a thermal cover. Officials are concerned the debris could cause a problem with future operations of the Common Berthing Mechanism. So Mission Control is going to open one section of the mechanism at a time in hopes of dislodging the debris. Hadfield will try and catch the debris, or at least confirm it has floated into space.

Meanwhile, Scott Parazynski is preparing for the final major task of today's EVA -- transporting a spare electronics box from the shuttle for attachment to the station's exterior.

1734 GMT (1:34 p.m. EDT)

Now five hours into today's EVA. The spacewalkers have started some clean up chores.

1727 GMT (1:27 p.m. EDT)

All the cable connections between the pallet and station have been unhooked. Preparations are now beginning for Susan Helms to use Canadarm2 to remove the pallet from the mechanism holding the structure to the station later today. Plans call for the arm to maneuver the pallet around in a test.

1715 GMT (1:15 p.m. EDT)

As the spacewalk continues comes word that NASA has decided to "grant an exemption" and drop its fight to stop U.S. businessman Dennis Tito from flying to the international space station this weekend aboard a Russian Soyuz spacecraft. Liftoff from the Baikonur Cosmodrome in Kazakhstan is scheduled for about 0738 GMT (3:38 a.m. EDT) on Saturday.

1658 GMT (12:58 p.m. EDT)

Now that power is being provided to Canadarm2 through the connections made by Parazynski today from the Destiny lab module's Power and Data Grapple Fixture, the spacewalkers can disconnect four power, command and video cables that were installed between the Spacelab pallet and station during the first spacewalk on Sunday. The four cables provided the initial power, computer commanding and video transmissions to the arm but will now no longer be required and must be removed to allow the pallet to be unlatched from the station and eventually returned to Endeavour's payload bay.

This is all part of the plan so the arm can "switch ends" using the lab's fixture as its base and the "hand" attached to the pallet as its free end.

1640 GMT (12:40 p.m. EDT)

With a round of applause in Mission Control, the redundant backup power supply is now working. The line is providing power to the Canadarm2's fixture on the Destiny laboratory, soon to become the crane's anchored base. It is unclear what cleared up the problem. The spacewalkers seemed to be as surprised as anyone since all they did was unhook and then re-mate a connector.

Once the spacewalkers re-install the remaining section of outer shielding, they will press ahead with the other tasks of this EVA. The main focus ahead will be disconnecting the various cables between the arm's launch pallet and Destiny lab's top side.

1631 GMT (12:31 p.m. EDT)

Parazynski has now re-mated that connector and bolted it back in place, and the ground has told the spacewalkers to re-install the micrometeoroid shield. The connector and its pins appeared normal. Another attempt to route power this this redundant line will occur shortly by the space station crew.

1624 GMT (12:24 p.m. EDT)

With his helmet-mounted video cameras, Parazynski is giving Mission Control a look at the downstream cable connector that might be causing the problem with the backup power string.

1616 GMT (12:16 p.m. EDT)

The spacewalkers have opened up the additional section of Destiny's shielding so a power connector can be checked.

1600 GMT (12:00 p.m. EDT)

Mission Control just instructed the spacewalkers to remove another section of the Destiny lab's outer skin -- the micrometeoroid shielding -- to gain access to another connector that could be causing the problem with the backup power line.

1555 GMT (11:55 a.m. EDT)

Hadfield is experiencing a problem releasing a bolt that holds the Video Signal Converter to the Spacelab pallet. He said he turned the bolt twice as many times as should be necessary but it still didn't release. So Mission Control has told him to re-tighten the bolt and not spend any more time on this task. The unit is no longer needed and was supposed to be taken aboard the station as a spare.

Meanwhile, engineers on the ground are coming up with some further troubleshooting for the backup string that is not supplying the power from the station to Canadarm2. The primary line is working, which is enough to operate the arm. But Mission Control wants the backup line to be operational for redundancy.

1543 GMT (11:43 a.m. EDT)

Helms reports the backup power string is still not working. This comes after spacewalker Parazynski re-checked the line's connectors. The primary power line is working, but officials aren't sure what is causing the problem on the redundant side.

1537 GMT (11:37 a.m. EDT)

After Parazynski checked another connector, Susan Helms inside the station is working to attempt flowing power through that redundant cable.

Hadfield continues other work, meanwhile. He is currently removing a Video Signal Converter (VSC) from the Spacelab pallet that is now no longer needed for Canadarm2's operation. The unit will be stowed aboard the station as a spare. Parazynski was slated for this task, but Hadfield is doing it since the wiring job is taking longer than envisioned.

1523 GMT (11:23 a.m. EDT)

Parazynski has disconnected the power cable in question. He reported it looked in good condition. Ground controllers are debating having the spacewalker check some other connectors in that redundant power string.

Meanwhile, spacewalker Hadfield is tidying the Canadarm2's launch pallet for its eventual return to Earth aboard Endeavour. He is currently stowing the quiver containing the three-foot long "superbolts" that held the arm during launch.

1505 GMT (11:05 a.m. EDT)

As a troubleshooting effort, Parazynski is going to unhook and then reconnect one cable in hopes of clearing the redundant power flow problem.

Again, the primary power line from the station to Canadarm2 is working just fine. However, the backup string is not flowing power for some unknown reason.

1455 GMT (10:55 a.m. EDT)

Spacewalker Parazynski has connected the primary power wiring between Canadarm2 and the Destiny lab. And with some work inside the station, power is now flowing from the outpost to its new space crane.

The backup power string still isn't working properly, however. During the initial checks power did not flow through the line. So further inspections are underway.

The video and computer connections have also been made by Parazynski. However, those connections can't be checked until later, Mission Control says.

1428 GMT (10:28 a.m. EDT)

Chris Hadfield has removed the no-longer-needed space station Early Communications antenna from the starboard side of the Unity node. The antenna was installed on the first U.S. mission to the station (STS-88) in December 1998.

Because the station's Ku-band communications system is now working, the Early Comm isn't required anymore. In addition, the antenna needed to be removed since the U.S. Airlock will be mounted to that area of Unity during the next shuttle mission in June. The astronauts describe the antenna as shaped like box, a bit bigger than a bread box. Its mass is about 100 pounds.

And Parazynski has now been given a "go" to continue with his other cable connection work despite the problem with the redundant power cable.

1426 GMT (10:26 a.m. EDT)

Hadfield has been told to forego attempting to a piece of debris from the antenna connector, which floated behind a thermal cover on Destiny's starboard berth.

Meanwhile, the redundant power cable connected by Parazynski is still not working. The internal check by Susan Helms didn't reveal any problems.

1412 GMT (10:12 a.m. EDT)

Both spacewalkers are idled at this point. Hadfield has found a piece of the broken connector. Controllers are currently discussing whether or not Hadfield can reach it for retrieval. And inside the station the Expedition Two crew is double-checking the internal cable connections to see if the routing problem is a configuration problem or a mis-wiring glitch outside by Parazynski.

1403 GMT (10:03 a.m. EDT)

Mission Control has told Hadfield that if he does find any of the connector pieces soon to just press ahead. The debris shouldn't be a concern.

Inside the station the Expedition Two crew has attempted to route power through some of the connections Parazynski recently made. However, it was unsuccessful. So Parazynski is checking to make sure the wires are correctly connected.

1355 GMT (9:55 a.m. EDT)

As Chris Hadfield worked to remove the Early Communications antenna to the space station he reported one of the connectors had come apart. Officials are talking about the situation before Hadfield press ahead with his work.

Meanwhile, Parazynski continues making the various wiring connections between the station and Canadarm2.

1315 GMT (9:15 a.m. EDT)

With the micrometeoroid shielding opened on the hull of Destiny, Parazynski is ready to begin making video, commanding and video cable connections between the station and Canadarm2's new anchored base.

In a pre-flight interview Parazynski described his work:

"EVA 2 is going to be very meticulous, delicate work as we basically rewire the space station robotic arm. As I mentioned earlier on EVA 1, the SSRMS is powered off of the Spacelab Pallet, and it's really not in a position where it can live for a long time. In fact, on flight 8A, the S0 truss gets installed right where the Spacelab Pallet is located right now, so it's not a permanent solution. We need to bring the power and the data off of the side of the Lab.

"So, what I'll be doing is reconfiguring wires underneath the surface of the Lab so that the Power and Data Grapple Fixture that the arm is already attached to can now transfer power and data and telemetry. If you can, envision just a small kitchen table-sized area with about 24 connectors, half of which are made of fiber-optic material. And, if you even look at them wrong, they might snap or break. This is the kind of environment that I'm going to be working in, and so, it's really critical that I not get tunnel vision. I have to keep the big picture, not just of the connector that I happen to be working on but my tethers and tools that are suspended off of my suit - make sure that they don't snag any of the adjacent connectors or do any harm. So it's kind of an interesting challenge.

"Earlier flights - 5A and 5A.1 - add additional cables on to this area, so, by the time that we get there on 6A, the cables that I'm going to need to interface with are at the very bottom, as luck would have it. So, I've got to very carefully extract these sensitive cables and bring them up and over the top. And so it's going to be, as I mentioned, very slow and deliberate work, but I'm looking forward to the challenge."

1304 GMT (9:04 a.m. EDT)

The spacewalkers are getting things set up for the first chores of today's excursion. Parazynski has climbed into a foot restraint on the end of Endeavour's robot arm; Hadfield is about to open the outer skin of the Destiny module so Parazynski can access the wiring.

1234 GMT (8:34 a.m. EDT)

EVA BEGINS. Astronauts Chris Hadfield and Scott Parazynski switched their spacesuits from shuttle-provided power to internal batteries at 8:34 a.m. EDT, signalling the official start of today's planned 6.5-hour spacewalk. The EVA is the 104th in U.S. space program history, the 64th to occur from the space shuttle, 20th dedicated to international space station construction and second of two of Endeavour's current mission. This is Parazynski's third EVA and Hadfield's second. It also marks the second spacewalk by a Canadian.

In a pre-flight interview Hadfield gave an overview of today's spacewalk:

"The purpose of space walk number one was to install the arm. The purpose of space walk number two is to permanently power the arm. The arm launched held inside its cradle, and it's powered through the end that is still in the cradle. But once it reaches around [and] grabs on to the Laboratory, like a huge inchworm with one end on each side, well then it's necessary to release all the power from the pallet side and actually go out and rewire it so that now the power's coming through the Laboratory side so that the arm is now powered from the correct end so we can bring that pallet home. We don't want to leave the pallet up there. It's just a container.

"So, on the second space walk, Scott's main job is to actually open up a whole panel, like an electrician taking part of your wall down, open up a big panel and then get in there with his hands and break a whole bunch of connections that were there temporarily and make a bunch of connections that are there to permanently power it through the grapple fixture and mechanism that's on the Laboratory end of the arm.

"Meanwhile, I will go and disconnect the wires on the other side of the Lab - the ones that are now no longer needed - so that we can bring that pallet home. I will also go and bring back an antenna that has been on the station for a few years now that is no longer needed now that we're increasing its communications capability. But also, that would be in the way for the subsequent flight. You have to get this antenna out of the way so that we can then install the airlock on the flight after ours; on assembly flight 7A. So, Scott's doing the wiring. I'm bringing back an antenna. I'll disconnect some wires that we don't need anymore.

"And then, finally, one more thing on the space walk number two. And that is the installation of a big, spare computer of sorts. It's really a switching unit - a DCSU. It's mounted on the wall of the payload bay of the shuttle. It's on a little heating blanket and connector so that it stays warm. And Scott's going to come down and hold on to it and disconnect it with his big power tool-the Pistol-Grip Tool-and then be flown up on the arm and then put it in place on a platform that's on the side of the Laboratory - the external stowage platform. And, I'll go around and help guide it into place with Scott. And, between the two of us, we'll get it clicked down and bolted down into place and hook up its little wire just to keep it warm. But, it's not to be used right away. It's just there as an on-orbit spare so that if the one they're using breaks which is important for the power distribution on the space station, they can go and remove the one that's broken and grab this one that we've brought up. Just like keeping a hardware store on orbit. You can make them go to the parts supply that's on the side of the station and install this new DC Switching Unit, so they can stay in business without having to wait for a whole shuttle to come up."

1222 GMT (8:22 a.m. EDT)

Running about a half-hour early, Chris Hadfield and Scott Parazynski have begun depressurizing space shuttle Endeavour's airlock for today's spacewalk. The EVA will officially begin once the astronauts switch their suits from shuttle-provided power to internal battery power.

0950 GMT (05:50 a.m. EDT)

The Endeavour astronauts were awakened at 3:41 a.m. to begin preparations for a second spacewalk by Canadian astronaut Chris Hadfield and Scott Parazynski. The primary goal of the excursion, scheduled to begin at 9:06 a.m., is to activate the socket on the Destiny laboratory module's hull where one end of the new Canadarm 2 space crane is plugged in.

The 57-foot-long robot arm was carried into orbit folded up and bolted to a Spacelab cargo pallet. The pallet was mounted on the Destiny module's hull Sunday and during the crew's first spacewalk, Hadfield and Parazynski connected temporary power cables and bolted the arm's two main booms together.

On Monday, arm operator Susan Helms, working inside the Destiny module, powered up the new crane, unlatched one end and anchored it to a power and data grapple fixture - PDGF - on the far side of Destiny's hull. The PDGF is a sort of high tech power socket delivering electricity to the arm and routing video and telemetry back to a computer workstation inside the lab.

The station eventually will be outfitted with a series of PDGFs mounted at strategic points around the outpost, allowing the multi-dextrous Canadarm 2 to walk end over end from one work site to another.

But the lone PDGF currently on the station is not yet fully activated. During today's spacewalk, Parazynski, riding on the end of the shuttle's robot arm, will open a utility panel on the lab's hull and make the necessary connections.

"We'll be doing a lot of the re-wiring to basically enable the space station arm to live on the space station permanently," Parazynski said. "We'll go out and with Chris's help, take off a shield on the side of the laboratory module and I'll spend the next hour and a half or so doing some fairly delicate work, surgery almost, rewiring some very delicate fiber optic cables to enable the space station arm to live permanently on the station."

The spacewalkers also will remove a no-longer-needed UHF antenna from the Unity module's starboard port where the station's main airlock will be installed during a mission in June. Then they will disconnect the Spacelab Pallet electrical umbilicals that initially powered the Canadarm 2.

Once the station's arm is powered through the PDGF, Helms will use it to lift the 3,000-pound Spacelab Pallet off the lab cradle assembly to make room for Parazynski to mount a 400-pound spare DC power converter on the station's hull.

The arm, with the Spacelab Pallet attached to one end, will be left in an extended position overnight. The shuttle crew, meanwhile, will re-open hatches to the station and help their colleagues unload the Raffaello cargo module attached to the station Monday.

NASA planners initially held open the possibility of having Parazynski and Hadfield attempt a bit of repair work on a jammed locking pin in the rotating joint where one of the station's two main solar array panels attaches to a central truss. The pin was causing friction, forcing the array's drive motor to work harder than its counterpart when moving the huge array to track the sun. Overnight, however, flight controllers successfully commanded the balky pin to retract and the so-called beta gimbal joint assembly was given a clean bill of health.

"We have some very good news. The BGA latch number two problem, which has been around for a while, has been solved, we think," astronaut Ellen Ochoa radioed from Houston. "It's been successfully unlatched and both arrays are now in autotrack ... and we think the problem is solved."

"Well that's good news," station astronaut James Voss replied. "Thanks."

MONDAY, APRIL 23, 2001

After 10 hours of united work today, the hatches between the international space station and Endeavour were re-closed at 3:26 p.m. EDT, allowing the shuttle's cabin pressure to be lowered for tomorrow's spacewalk by Chris Hadfield and Scott Parazynski.

The 6.5-hour spacewalk is due to begin just after 9 a.m. EDT. The two men will rewire the base of the newly installed Canadarm2 so it can operate from its new home on the Destiny Laboratory, to remove a communications antenna from Unity which is no longer needed and to mount a spare electrical converter unit on a stowage platform on Destiny for future Station use.

Near the end of their work day today, shuttle commander Kent Rominger and pilot Jeff Ashby supervised a one-hour firing of Endeavour's jets to gently raise the orbit of the ISS about 2 1Ž2 statute miles, from 237.8 statute miles to 240.3 statute miles. Two more reboosts are planned on Wednesday and Thursday to leave the Station at the correct altitude for the arrival of a Russian-commanded "taxi" crew, including tourist Dennis Tito, next week delivering a fresh Soyuz return vehicle to the complex.

1600 GMT (12:00 p.m. EDT)

RAFFAELLO ATTACHED. The Raffaello Multipurpose Logistics Module has been mounted to the international space station with its 7,500 pounds of equipment and experiments for the U.S. Destiny laboratory module. The station astronauts are slated to enter the $150 million pressurized module tomorrow to start unpacking its contents.

Raffaello's cargo includes EXPRESS Racks No. 1 and 2 that will be used to conduct science experiments aboard the station. The EXPRESS (Expedite the Processing of Experiments to the Space Station) Rack concept was developed to support small payloads on orbit with a shortened ground integration period. The EXPRESS Rack allows payloads to be changed out in space.

There are also four Resupply Stowage Racks (RSR) and four Resupply Stowage Platforms (RSP). These eight racks contain equipment required for activation of the two EXPRESS racks, components to augment existing station systems, spare parts for systems already on the station, in addition to food and supplies to support the crew. Resupply Stowage Racks and Resupply Stowage Platforms use Cargo Transfer Bags to carry components to the station but the racks, platforms and bags themselves remain in the Raffaello module and are returned to Earth aboard the shuttle.

Once emptied, the crew will load old equipment, trash and other cargo into Raffaello for return to Earth. Plans call for the module to be detached from the station and put back into Endeavour's payload bay on Friday.

Raffaello is a cylindrical module stretching 21 feet in length and 15 feet in diameter.

Two similar modules have been built -- Leonardo and Donatello. Leonardo made its debut flight last month and Donatello is slated to fly this summer. All three modules are reusable, and will make trips to orbit, unloaded by astronauts and then brought back to Earth. They are each designed to fly up to 25 times -- 10 flights during station assembly and 4 or 5 missions per year during the outpost's operational life span.

Although built by the Italian Space Agency, the modules are owned by NASA.

1559 GMT (11:59 a.m. EDT)

Raffaello is just a couple of inches away from the Unity node's berthing port.

1532 GMT (11:32 a.m. EDT)

Mission Control reports the shuttle's robot arm has raised the Raffaello module to a point level with the Unity node. Arm operator Scott Parazynski will begin moving Raffaello toward the station for docking shortly after verifying proper alignment.

1516 GMT (11:16 a.m. EDT)

European astronaut Umberto Guidoni described what Raffaello is carrying in a pre-flight interview:

"The MPLM is really the module we use to carry all the spare parts and experiments on the space station and also back to Earth. So, it will be our truck, space truck, that we will be using back and forth from the ground to the space station and back. It is inside them, they can be [configured] in different [ways] depending on the kind of materials we are bringing on the station. In our particular flight, we will be bringing two EXPRESS [racks] that are pretty much the standard size rack that are used on board the station. And, we will be also carrying some of the [experiments] to put on these racks. Also we will be carrying food and clothes for the Expedition Two crew. And as well as spare parts for the EVA that will be conducted from the station in the following months. And also some spare parts for the space station; like, for example, DC-DC converters and computers and other things of this nature.

"In particular, we will be bringing also a scale model of the SSRMS for the crew to train. I mean, it's always very important to have a physical representation of the arm. Because this station arm is very complicated. It's really one generation, next generation arm with respect to the arm we are flying on the shuttle. In particular, this arm has 7 degrees-of-freedom that makes the overall motion of the arm very complex so that, before you start driving the arm, you should be very familiar with all the position it can get. And, that's why we need a model on board the station. We will be carrying that as well."

1458 GMT (10:58 a.m. EDT)

Endeavour's robot arm is now in motion, lifting Raffaello out of the payload bay bound for the international space station.

Meanwhile, subscribers of our Mission Theater can watch a video clip of the hatch opening and emotional welcoming ceremony today by the shuttle and station crews.

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And click here for a complete listing off all the videos currently available to watch.

1454 GMT (10:54 a.m. EDT)

The remote umbilical running to Raffaello has been demated. The umbilical provided power for internal systems and heaters to the cargo module since launch. And now the retention latches physically holding the module in the payload bay have been opened. That will clear the way for the robot arm to unberth Raffaello.

1433 GMT (10:33 a.m. EDT)

In a pre-flight interview shuttle robot arm operator Scott Parazynski described the process of attaching Raffaello to the international space station:

"The installation of the MPLM requires use of the shuttle's robotic arm, which I'll be flying both on the installation and removal. Installation occurs on flight day five, and Umberto Guidoni, from the European Space Agency, will be my trusted ally and will be helping me all through the process. What we'll first do is grapple the MPLM in the payload bay.

"Once that's successfully accomplished, we'll demate a rigid electrical umbilical that we'll deploy out of the way. That basically is used to control heaters and other electrical avionics during a launch and landing.

"Once we've done that, we'll very slowly and carefully lift the MPLM out of its V-guides - clear of the shuttle's payload bay - and then reorient the MPLM so that it's in a proper configuration high above the payload bay to dock with the Node.

"We're going to be taking it up to the nadir port of the Node on space station. And, using a number of different sensors there, Umberto's going to be turning on the Space Vision System using a series of black dots to calibrate the Vision System to give us guidance to very precisely align the MPLM with the berthing interface. I'll also be using a centerline berthing camera, which has some other cues to fly out any attitude errors and help me stay on track as I berth the MPLM on the side of the Node."

1426 GMT (10:26 a.m. EDT)

RAFFAELLO GRAPPLED. Endeavour's own robotic arm now has a firm grasp on the Raffaello Multi-Purpose Logistics Module (MPLM) riding in the shuttle's payload bay. The arm will gently lift the module out of the bay shortly and attach it to the nadir port of the space station's Unity node.

Inside Raffaello resides about 7,500 pounds of cargo -- equipment, experiments and supplies -- to outfit the station's new Destiny laboratory. The astronauts will begin unpacking the cargo tomorrow, a job that will take several days.

The Italian-built module will be returned to Endeavour's bay on Friday for the trip back to Earth for later reuse.

1416 GMT (10:16 a.m. EDT)

Canadarm2 has grappled the international space station's Destiny laboratory module, completing the "step off" from the Spacelab pallet that the arm rode into space. Canadarm2 has now arrived at its home for at least the next year before it is moved to another part of the station.

The Canadian-made, 58-foot arm, however, remains attached to the pallet at the other end. Once spacewalkers route the power and data lines to the arm via the Destiny fixture tomorrow, the pallet end can be released to become the free hand.

Unlike the shuttle arm, Canadarm2 is not permanently anchored at one end; instead, either hand is equipped with a Latching End Effector (LEE) that can be used as an anchor point while the opposite one performs various tasks, including grabbing another connecting point on the station known as the Power and Data Grapple Fixture. This design gives Canadarm2 the unique ability to move around the station like an "inchworm," flipping end-over-end among grapple fixtures located on the exterior of the station.

1345 GMT (9:45 a.m. EDT)

Canadarm2 has sailed through its initial round of testing today as the space station astronauts commanded the 58-foot limb through a series of range-of-motion checks. The arm's free hand will soon grapple the Destiny lab module, completing today's milestone first "step" by Canadarm2.

Meanwhile, Endeavour astronaut Scott Parazynski is standing by to use the shuttle's arm to grapple the Multi-Purpose Logistics Module in the shuttle's payload bay. He will then maneuver the module, nicknamed Raffaello, to its docking port on the Unity node of the station. Raffaello is loaded with supplies, equipment and experiments for the station.

1114 GMT (7:14 a.m. EDT)

One end of Canadarm2 has been released from its launch container. The other end remains latched to a fixture on the pallet, receiving power and commanding from the space station.

The arm now will be put through its paces before the free end locks on to the Destiny module's grapple fixture. Once attached to Destiny, the stage will be set for tomorrow's spacewalk by Chris Hadfield and Scott Parazynski to wire up the arm to receive power and commands through Destiny's fixture.

In a pre-flight interview Parazynski explains:

"Of course, the space station arm is still based on the Spacelab Pallet, and what it really needs to do is be based off of the Laboratory module. We're bringing that Spacelab Pallet back home. Its new house actually is on the side of the Laboratory module on an interface that we call the PDGF, or Power and Data Grapple Fixture, so the crew will basically fly the space station arm up and over to the other side of the Laboratory module and grapple this Power and Data Grapple Fixture. And that'll be the preparatory steps for EVA 2."

Parazynski continues by describing the work he will be doing during tomorrow's spacewalk:

"We need to bring the power and the data off of the side of the Lab. So, what I'll be doing is reconfiguring wires underneath the surface of the Lab so that the Power and Data Grapple Fixture that the arm is already attached to can now transfer power and data and telemetry. If you can, envision just a small kitchen table-sized area with about 24 connectors, half of which are made of fiber-optic material. And, if you even look at them wrong, they might snap or break. This is the kind of environment that I'm going to be working in, and so, it's really critical that I not get tunnel vision."

1033 GMT (6:33 a.m. EDT)

Expedition Two astronaut Jim Voss just reported that he and Susan Helms are starting activities with Canadarm2 from the station's Robotics Work Station in the Destiny lab. The focus today will be unlatching one end of the 58-foot arm from its launch container and performing a series of motion tests. Then the free end will attach itself to the power and data socket on Destiny, marking the arm's first "step" in space.

The joint shuttle-station crew recently completed a safety briefing and tour of Alpha following their emotional welcoming ceremony.

0930 GMT (5:30 a.m. EDT)

The hatches between the international space station and space shuttle Endeavour were opened this morning, uniting the 10 astronauts from both craft for the first time at about 5:25 a.m. EDT (0925 GMT).

Endeavour docked to the station on Saturday, but the shuttle's lower cabin pressure necessary for yesterday's spacewalk forced the meeting of crews to be put on hold until today. This meeting will be short, however, as the hatches will be re-closed later this afternoon so Endeavour's pressure can be again lowered for tomorrow's spacewalk.

In less than an hour the astronauts will get down to business as the new Canadarm2 will be "walked off" its launch pallet, attaching itself to a fixture on the opposite side of the Destiny lab module.

Later this morning Endeavour's robotic arm will be used to lift the Italian-built Raffaello "cargo moving van" module out of the shuttle's payload bay for connection to the station's Unity node.

Watch this page for updates throughout the day!

SUNDAY, APRIL 22, 2001

Spacewalkers Chris Hadfield and Scott Parazynski successfully assembled and deployed the space station's new $900 million Canadian-built robot arm today. Shortly after the spacewalkers returned to Endeavour's airlock, station astronaut Susan Helms, operated the arm for the first time from a computer work station in the Destiny laboratory module. Read our full story.

Also see our updated spacewalk stats page.

1855 GMT (2:55 p.m. EDT)

EVA ENDS. Space shuttle Endeavour's airlock is now being repressurized, officially bringing today's highly successful spacewalk by Chris Hadfield and Scott Parazynski to a conclusion. The EVA lasted seven hours and 10 minutes.

This was the 103rd spacewalk in U.S. space program history, the 63rd to occur from the space shuttle, 19th dedicated to international space station construction and first of two of Endeavour's current mission. This was Parazynski's second EVA; Hadfield was a spacewalk rookie before today.

Meanwhile, the Canadarm2 is now in motion. Expedition Two astronaut Susan Helms is guiding the arm -- folded at the elbow -- in a procedure to raise its booms. The arm will "step off" its launch pallet tomorrow.

1834 GMT (2:34 p.m. EDT)

Subscribers of our Mission Theater can watch a video clip of the Canadarm2 being unfolded by the spacewalkers.

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And click here for a complete listing off all the videos currently available to watch.

1828 GMT (2:28 p.m. EDT)

The spacewalkers will be heading back into the airlock to conclude today's excursion very shortly. The EVA now passing 6 hours, 43 minutes in duration.

The ground just played the Canadian national anthem in commemoration to the successful attachment of Canadarm2 to the international space station today. The $900 million arm is the first major contribution by Canada to the station project. It's role will be performing future assembly and maintenance work on the orbiting outpost starting with the U.S. airlock connection during the next shuttle mission in June.

Today's EVA by Chris Hadfield is also the first spacewalk by a Canadian.

1815 GMT (2:15 p.m. EDT)

A communications check between the space station and the spacewalkers via the new UHF antenna installed to the outpost earlier today has been completed successfully. In addition, the spacewalkers, continuing their efforts to clean up and put away tools and tethers, paused outside the Destiny lab window so the station crew could shot some video with the IMAX camera.

Also at this point the shuttle's robotic arm is being moved into position to provide a view of the Canadarm2's upcoming movement.

1745 GMT (1:45 p.m. EDT)

Now six hours into today's spacewalk.

Meanwhile, the space station crew is preparing to starting checking out the Canadarm2's video system and the upcoming boom raise.

1726 GMT (1:26 p.m. EDT)

The spacewalkers are now beginning to head back into Endeavour's payload bay to the airlock to start stowing equipment.

1715 GMT (1:15 p.m. EDT)

With the tightening by Parazynski now wrapping up, Hadfield is reponsible for releasing some latches on one end of the arm in preparation for its further operations later today.

1701 GMT (1:01 p.m. EDT)

Mission Control has decided to keep this spacewalk's agenda unchanged. Officials have decided to forego the earlier thinking that the spacewalkers might transfer a spare electronics box from the shuttle to the station today instead of on EVA No. 2.

1652 GMT (12:52 p.m. EDT)

The spacewalkers are going to make one more round of manual tightening on the fastener bolts. The EVA has surpassed the five-hour mark.

1643 GMT (12:43 p.m. EDT)

The spacewalkers are switching their Pistol-Grip Tools to manual mode so they can finish work to torque the bolts by hand, Mission Control reports.

1639 GMT (12:39 p.m. EDT)

Subscribers of our Mission Theater can watch a video clip of today's UHF antenna deployment.

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And click here for a complete listing off all the videos currently available to watch.

1625 GMT (12:25 p.m. EDT)

Bolt tightening by the spacewalkers continues as Hadfield and Parazynski torque all the fasteners on Canadarm2.

SUNDAY, APRIL 22, 2001
1600 GMT (12:00 p.m. EDT)

Mission Control says Hadfield's eyes are better now. Today's spacewalk is now four hours, 15 minutes in duration.

1552 GMT (11:52 a.m. EDT)

Hadfield is pressing ahead with his chores to install the Expandable Diameter Fasteners.

1543 GMT (11:43 a.m. EDT)

Chris Hadfield, making his first spacewalk, is reporting some eye irritation. His eyes are tearing up. He increased his air purge inside the spacesuit, but that didn't seem to help.

1526 GMT (11:26 a.m. EDT)

Canadarm2 is now unfolded. The spacewalkers will now install eight Expandable Diameter Fasteners in the hinges of the arm booms. The fasteners expand in the hole and lock in place to make the arm rigid.

1510 GMT (11:10 a.m. EDT)

While holding on to the arm, Hadfield is riding the shuttle's arm as the station's new Canadarm2 is being unfolded.

SUNDAY, APRIL 22, 2001
1506 GMT (11:06 a.m. EDT)

Chris Hadfield has climbed back into a foot platform on the end of space shuttle's robot arm. It is from this position he will manually flip over the upper quarters of the Canadarm2 booms to unfold the arm.

1501 GMT (11:01 a.m. EDT)

"Weightlifting in weightlessness." That is what the spacewalkers just demonstrated by lifting the folded up Canadarm2 by about 30 degrees. This will allow the booms to be unfolded and hinges bolted together.

1448 GMT (10:48 a.m. EDT)

Hadfield has now finished his chores to release the 16 jackbolts and to remove the superbolts, following the completion of the same work on the other side by Parazynski.

The next task will be the initial raising of the arm booms in preparation for them to be unfolded and assembled.

1430 GMT (10:30 a.m. EDT)

Parazynski is loosening the 16 jackbolts and removing four superbolts on his side with Hadfield assisting by stowing away the superbolts in container called the "quiver" on the pallet. Once Parazynski is finished, they will reverse roles with Hadfield releasing all of his bolts.

1419 GMT (10:19 a.m. EDT)

The $900 million Canadarm2 is now committed to life aboard the international space station. The spacewalkers have begun the methodical process of releasing bolts holding the arm in its pallet. The bolts cannot be retightened in space, meaning the arm can no longer be returned to the shuttle for return to Earth.

The process underway is releasing four smaller bolts on each of the eight "super bolts" that secure the arm in the Spacelab pallet. The 32 smaller "jackbolts" held tight four-foot-long "superbolts".

1418 GMT (10:18 a.m. EDT)

"Now it's time for the main event," says the spacewalkers as they prepare to begin releasing 40 bolts holding the Canadarm2 in its folded up launch configuration.

1415 GMT (10:15 a.m. EDT)

The spacewalkers continue removing the thermal covers on Canadarm2, creating "a huge load of laundry" that will be brought back to the shuttle.

1400 GMT (10:00 a.m. EDT)

Mission Control just told the spacewalkers that they remain well ahead of schedule. If this continues, the crew may be asked to perform today a task originally slated for the mission's second spacewalk -- the transfer of a spare Direct Current Switching Unit from the shuttle's payload bay to the station.

1345 GMT (9:45 a.m. EDT)

Now passing the two-hour mark in today's scheduled 6.5-hour spacewalk.

1339 GMT (9:39 a.m. EDT)

With two good strings of power being fed from the station to Canadarm2, Mission Control has given the spacewalkers a "go" for continued work to deploy the arm.

The spacewalkers will now remove various thermal covers on the arm before the exhaustive work to remove 32 small bolts and eight "super bolts" holding it in the Spacelab pallet.

1329 GMT (9:29 a.m. EDT)

The UHF boom is now attached to the station and its two antenna ray domes have been deployed.

The antenna is an element of the international space station's UHF Communications Subsystem, working with the Space-to-Space Station Radio (SSSR) transceivers on the outpost. A second antenna will be delivered on STS-115 next year.

Once in operation the UHF subsystem will be used for space-to-space communication (voice, commands and telemetry for the space station). It can support up to five users on the same frequency and provides two-way voice communications between the station and spacewalkers, the station and space shuttle and between Mission Control in Houston and spacewalkers (using the UHF with the S-band subsystem).

It will also provide shuttle commanding of critical station functions such as going to free drift during undocking operations and transmission of critical station telemetry to the shuttle during undocking operations.

In pre-flight interview Parazynski explained the importance of the antenna:

"The UHF antenna that we're deploying is a great added capability. As we currently rendezvous with the space station, we have to use a VHF antenna, very similar to what's used in general aviation these days. It's line of sight and has some limitations. It also requires flying in an extra box of equipment every docking flight. Now what we'll be able to do on rendezvous is just use our regular UHF antennas in the orbiter to communicate during rendezvous.

"It's also going to be the primary communication path for EVA communication so that, when the station crew is outside doing an EVA, they can talk to their IVA crewmember via the UHF radio. So a very powerful capability."

1322 GMT (9:22 a.m. EDT)

Expedition Two astronaut Susan Helms inside the international space station has applied power to the Canadarm2, which is still folded up in the Spacelab pallet attached to the Destiny lab module. The power was routed via the cable connections made a short while ago by spacewalker Parazynski.

Meanwhile, the spacewalkers are working to attach the UHF antenna to the bottom of Destiny, just above Endeavour's payload bay.

1302 GMT (9:02 a.m. EDT)

The UHF antenna has been freed from its launch position on the pallet. Riding on the end of the shuttle's robot arm, Chris Hadfield will now carry the four-foot boom to the opposite side of the Destiny module for attachment. Hadfield described it as "flying this thing like a huge Robin Hood-type lance out in front of me."

1255 GMT (8:55 a.m. EDT)

The spacewalkers are now in the process of unbolting the Ultra-High Frequency (UHF) antenna from the Spacelab pallet where it rode into space aboard Endeavour. Shortly the antenna will be removed from the pallet for installation on the side of the station's Destiny lab module.

1245 GMT (8:45 a.m. EDT)

Parazynski has connect the four cables between the international space station and Canadarm2. These are a primary and a backup power cable and a primary and a back up computer command and video cable. The connections are vital, providing keep-alive power for the folded up arm.

It is now up to the station crew to ensure power is flowing to the arm. The connections are most critical today to route power to heaters on the arm. The spacewalkers will press ahead with other tasks -- including attachment of an antenna on the station -- to allow the arm to warm up before unfolding the booms a little later.

1230 GMT (8:30 a.m. EDT)

The spacewalkers are finishing up their sortie setup chores and preparing to get down to business. Parazynski will begin making power and data cable connections to the Canadarm2 while Hadfield is getting a foot platform in place on the end of the shuttle's robot arm.

Hadfield can be distinguished by the red stripes on his spacesuit; Parazynski has a solid white suit.

1145 GMT (7:45 a.m. EDT)

EVA BEGINS. Astronauts Chris Hadfield and Scott Parazynski switched their spacesuits from shuttle-provided power to internal batteries at 7:45 a.m. EDT, signalling the official start of today's planned 6.5-hour spacewalk. The EVA is the 103rd in U.S. space program history, the 63rd to occur from the space shuttle, 19th dedicated to international space station construction and first of two of Endeavour's current mission. This is Parazynski's second EVA; Hadfield is a spacewalk rookie. It also marks the first spacewalk by a Canadian.

In a pre-flight interview Parazynski provided a comprehensive preview of today's spacewalk:

"It's six and a half hours nominally planned - a very tightly choreographed activity with John Phillips, our intravehicular crewmember, kind of as the quarterback of this whole activity. Chris will be setting up the arm, getting a Portable Foot Restraint out of, basically, a tool locker in the payload bay, installing that on the arm. While he's doing that, I'll be climbing up on the Laboratory module. I'll be checking on a slide wire that runs alongside of it, verifying that it's intact. And then, once that's complete, I'll switch my safety tether reel on to the Laboratory.

"I'll go up to the Spacelab Pallet on the top of the Lab and hook up four different connectors, and, these are critical to the life of the station arm. Both power and data and video lines run through these. Once all four connectors are mated, we can then begin giving the arm keep-alive power. And, that's something that the space station crew inside the Lab will do on their laptop computers.

"Once that's complete, Chris will be on board with me. We'll then move the UHF antenna from the Spacelab Pallet, off of that and down around to the other side of the Lab. We'll unbolt four bolts on the base of the antenna. Chris will get another three on the shaft of the antenna. He'll then lift it off of the pallet and ride around on the arm to the installation spot. At that point, I'll receive the base of the antenna soft dock it. Then I'll torque up the four base bolts, and then I'll allow Chris to clear the area. And as he's doing that, I'll swing up this UHF boom. And, it's a remarkable piece of hardware, actually. As the boom deploys, the two antenna ray domes also deploy in turn, and I think it's going to be really an interesting thing to see on downlink for folks.

"Once that's accomplished, another couple of bolts, an electrical connector and the UHF antenna should be ready to operate. A few other commands that the space station crew will be required to do inside to make that happen.

"Following that, both Chris and I will head back up to the Spacelab Pallet. And, there are a number of jack bolts that have to be released to basically lessen the torque on bolts that we call "super bolts," and they're almost 4-feet long. Thus the name. And so each of these bolts [is] torqued down to about 18,000 pounds. To achieve that, they have jack bolts that add a little extra torque and keep the application of the torque symmetric. So, we have to, in sequence, un-torque jack bolts around the head of the super bolt, and it's a very methodical, sequenced activity.

"Once all the jack bolts are backed off appropriately, then I'll remove all four of my super bolts and hand those over to Chris. And, he'll receive them while he's still on the arm and put them into a device that we call the "quiver." It's just like an arrow quiver you know, from Robin Hood or whatever. But basically, [we] install the super bolts in four long slots, and then, he'll go to his end and remove the super bolts on his end of the Spacelab Pallet. I'll receive them and install his super bolts in the quiver and close up the top of that, and we're ready to proceed with the really critical portion of the EVA, which is the assembly of the arm itself.

"What this entails is, first of all, removing some expandable diameter fasteners. These are bolts that, as you apply torque to them, they actually expand in the hole and lock in place, so I have to get these out of their launch position. There are a number of clevises that exist at the hinge of the arm. The arm in its launch configuration is essentially folded in half, and right here is the hinge joint. If you can imagine, this entire upper surface is folded back on to itself. I kind of liken the arm to a spider or praying mantis. It kind of gracefully gets unfolded and becomes a very powerful structure once it's completely assembled. But once the expandable diameter fasteners have been removed, I actually lift up the booms manually so that I can access all four of the lower bolts.

"Then Chris will come by on the arm and swing this entire upper boom up and over, and this also requires a great deal of coordination between Jeff Ashby, who's driving the arm, and Chris on the arm to make sure that he can reach during the maneuver. And, it's also close to a number of reach limits and singularities on the shuttle arm. So, it's going to be a very slow and methodical activity to get Chris in up and over there.

"Once that's completed, then I will free float all the way around and install eight of these expandable diameter fasteners. It's a key activity on the flight because, if we don't have all eight of those installed properly, the arm won't have the proper rigidity to do its job. So Chris, at the end of the arm, can actually wiggle it, shake it - very gently obviously - to help align it so that I can install the expandable diameter fasteners. Once they're installed Chris will come back to the upper portion of the arm. I'll be on the lower portion of it, and we'll torque up those expandable diameter fasteners.

"And, basically that's the completion of EVA 1. It's a lot of work all fit into a six-and-a-half-hour EVA, but we've been doing really well in the pool. I have a lot of confidence that things are going to go well in flight."

1132 GMT (7:32 a.m. EDT)

Airlock depressurization has started.

1125 GMT (7:25 a.m. EDT)

The spacewalkers are finishing up the pre-breathing procedure to purge their blood streams of nitrogen to protect against "the bends" during today's excursion.

The airlock depressurization is expected to begin shortly. The spacewalk will officially start when the two crew members switch their suits to internal battery power.

1114 GMT (7:14 a.m. EDT)

Mission Control has revised its estimated start time for today's spacewalk. The EVA is now expected to begin around 7:36 a.m. EDT based upon completion of the spacewalkers' pure oxygen pre-breath and depressurization of the airlock.

1050 GMT (6:50 a.m. EDT)

The two spacewalkers aboard Endeavour have donned their suits. They are now beginning the process of breathing 100 percent pure oxygen to protect against getting "the bends" in the low-pressure of the spacesuits during today's 6.5-hour spacewalk. Mission Control does report the astronauts are running about a half-hour behind schedule in the spacewalk preparation timeline. So the spacewalk is now targeted to start around 7:50 a.m. EDT.

1042 GMT (6:42 a.m. EDT)

The Spacelab pallet carrying the Canadarm2 has been successfully mounted to the international space station's Destiny module. The shuttle's robot arm used to move the pallet from Endeavour's payload bay to the station will now ungrapple the pallet in preparation for use in the upcoming spacewalk.

Today's spacewalk will be the first for a Canadian. Mission specialist Chris Hadfield has trained about four years for the job of assembling and bringing Canadarm2 to life. He described the events to occur today in this pre-flight interview:

"We launch with a new space station arm back in the payload bay of the shuttle. And, it's in a cradle, a big pallet. The arm's too big just to lay in the shuttle. It has to be folded in half and then folded in half again, like a dead spider with its legs all folded up on itself. And we are going to use the shuttle arm to pick that up and attach it to the station. But then, it's still just dead and folded on to the station. And that's where the space walk comes in.

"Myself and Scott Parazynski, we're going to go outside and hook up electrical wiring to that arm so that it starts to heat up and warm up and bring its computers to life. And then, we will undo the huge bolts that held it in place to take all the vibration and acceleration during launch. And then, once it is powered and unbolted, we will actually unfold the big arms and bolt them together, sticking in these expandable fasteners. And, out we'll space walk, with our huge power tool, we will drive these to bring that arm to a stiff state, to have its arm unfolded and built.

"So that, now, it is in a posture where it is powered and it is stiff enough that it can then come to life and start to raise itself and be ready to walk off on its own."

1020 GMT (6:20 a.m. EDT)

After moving into orbital daylight and resolving clearance concerns with the station's Ku-band antenna, Jeff Ashby resumed moving the Spacelab pallet with the shuttle's robot arm. The pallet is now just a couple of feet from its mounting location on the station's Destiny lab module.

A 300-pound, 4-foot box called the Lab Cradle Assembly is what the pallet will be attached to. The cradle assembly features a large claw that can capture objects and hold them to the station.

0933 GMT (5:33 a.m. EDT)

Concerned about good visibility as he moves the Spacelab pallet with Canadarm2 using the shuttle's robot arm, Mission Control has told operator Jeff Ashby he can hold until orbital sunrise in about a half-hour. This is a very tricky affair as Ashby guides Endeavour's arm over the shuttle's nose without any good lighting or cameras.

This wait won't have any significant impact to today's activities. Ashby was actually running a bit ahead of schedule.

The two spacewalkers continue their preparations aboard Endeavour. Scott Parazynski is a veteran spacewalker, but Chris Hadfield will be making history today as he becomes the first Canadian to walk in space.

And, of course, the 58-foot robotic arm being attached to the space station today was made by Canada.

"Good morning Canada... I mean Endeavour," mission control said in a morning email to the crew. "There may be more excitement down here north of 49 than where you are up there. Canada will be watching and the entire Canadian team sends you their best wishes for a successful installation of Canadarm 2 and the beginning of operations using Canada's contribution to the ISS."

0900 GMT (5:00 a.m. EDT)

Endeavour pilot Jeffrey Ashby, operating the shuttle's robot arm, lifted a Spacelab pallet carrying the new Canadarm 2 space crane out of its berth in the ship's cargo bay at 4:42 a.m. EDT. If all goes well, the pallet will be mounted on the hull of the space station's Destiny laboratory module shortly before 6 a.m., setting the stage for a planned six-and-a-half-hour spacewalk by Canadian astronaut Chris Hadfield and Scott Parazynski.

The new robot arm was launched folded up and unpowered and the first item on the agenda today is for Hadfield and Parazynski to attach interim power cables. The arm later will receive power and relay telemetry through a so-called power and data grapple fixture, or PDGF, already in place on Destiny's hull.

After connecting the interim power cables, Hadfield and Parazynski will unbolt eight so-called "superbolts" holding the folded space crane to the Spacelab Pallet.

"The number one objective during spacewalk number one is to provide power to the arm so it can warm itself up," Hadfield said before launch. "So the first thing we have to do is hook up the wiring and then once it's warmed up for a little while, we will start undoing these enormous superbolts."

But first, the spacewalkers will remove a new UHF space-to-space radio antenna from the shuttle's cargo bay and mount it near the forward end of the Destiny module. Then, with the Canadarm 2 properly warmed up, they will turn their attention to unfolding its booms and bolting them together.

"With myself riding on the end of the shuttle arm and Scott providing a manual lift and then guidance on the other end, we are going to unfold that arm through 180 degrees and actually bolt it together," Hadfield said.

Lead spacewalk planner Jeff Patrick said Parazynski, his feet anchored in a foot restraint, "basically does a clean and jerk on the booms, raises the lower booms up so they're about at his head level."

The boom joints will be bolted together with fasteners that work like concrete bolts, expanding internally as they are tightened to rigidly lock the arm members together. Once that work is complete, Hadfield and Parazynski will return to Endeavour's airlock, ending the excursion around 1:36 p.m.

A few minutes later, space station astronaut Susan Helms, working at a robotic work station inside Destiny, will send commands to elevate the Canadarm 2 boom into an overnight park position.

0854 GMT (4:54 a.m. EDT)

Under the control of Jeff Ashby, the shuttle's robot arm has picked the Spacelab pallet out of Endeavour's payload bay for delivery to the Destiny laboratory module.

The pallet is 13 feet (3.96 meters) wide and 15 feet (4.57 meters) long. Spacelab pallets can carry up to 3 tons (2.72 tonnes) of equipment and have flown on 13 prior flights supporting space experiments and other equipment.

0830 GMT (4:30 a.m. EDT)

This promises to be an action-packed day in space today as the Canadian-made space station robotic arm is attached to the orbiting outpost with the help of two spacewalking astronauts.

The work is already underway at this hour as Endeavour pilot Jeff Ashby has grappled the Spacelab pallet containing Canadarm2 using the space shuttle's arm. The shuttle arm will be used to raise the pallet out of the payload bay and mounting it to the Destiny laboratory module above Endeavour's nose.

Meanwhile, mission specialists Chris Hadfield and Scott Parazynski are on the middeck of Endeavour beginning preparations for today's planned 6.5-hour spacewalk to assemble the $900 million Canadarm2 and connect a new space-to-space communications antenna to the station.

The spacewalk will start once the pallet is firmly mounted to Destiny.

SATURDAY, APRIL 21, 2001

Shuttle skipper Kent Rominger guided Endeavour to a glacial docking with the international space station today as the two spacecraft sailed 243 miles above the south Pacific Ocean at five miles per second. Read our full docking story.

1608 GMT (12:08 p.m. EDT)

The outer-most hatch of the international space station has been opened by the Endeavour crew. The astronauts are making their way to the station's doorstep to pick up spacewalk tools and some other items left there by the station crew yesterday. The shuttle astronauts will then leave four bags of water, some IMAX camera film and computer equipment that the station residents can retrieve later.

The hatch should be closed by the shuttle astronauts within the next two hours. Later today the crew will spend some time making final preparations for tomorrow's spacewalk by Chris Hadfield and Scott Parazynski to mount the new Canadian-made robotic arm to the space station's Destiny lab. The seven astronauts are due to begin an eight-hour sleep period at 6:41 p.m. EDT.

The action tomorrow begins with the shuttle's 50-foot arm unberthing the pallet containing the station's Canadarm2 from Endeavour's payload bay at 4:36 a.m. EDT. The spacewalk prep timeline will start a short time later at 4:51 a.m. EDT.

The pallet is expected to be attached to the Destiny module's Lab Cradle Assembly (located above Endeavour's nose) at 5:46 a.m. EDT. The spacewalk is scheduled to start at 7:21 a.m. EDT as Hadfield and Parazynski embark on a 6.5-hour excursion to assemble and deploy the 58-foot long Canadarm2 that will be used extensively in the continued construction of the space station.

The first meeting of the shuttle and station crews is scheduled for Monday. They can't be united until after the spacewalk given the lowered cabin pressure in Endeavour for tomorrow's EVA.

1538 GMT (11:38 a.m. EDT)

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1449 GMT (10:49 a.m. EDT)

Station astronaut Jim Voss reports the leak check on the docking adapter is complete. And now the vestibule between the shuttle and station will be pressurized. All this work is being done in advance of Endeavour's astronauts opening the outer hatch of the station in about a half-hour.

1443 GMT (10:43 a.m. EDT)

The Expedition Two crew has started the initial leak checks on the station's side of the docking port. And also the station's control-moment gyros have assumed attitude control of the ISS-shuttle stack.

1434 GMT (10:34 a.m. EDT)

The initial leak check has been completed without any problems, verifying a good air-tight seal.

1415 GMT (10:15 a.m. EDT)

The shuttle crew is now beginning the initial hatch leak checks following today's docking. Plans call for Endeavour's astronauts to enter the outer-most compartment of the station in about hour, dropping off bags of water, computer equipment and IMAX camera film on the doorstep of the orbiting outpost. The Expedition Two crew will then retrieve the supplies later.

A joint meeting between the crews won't occur for a couple of days because of different air pressures in the two spacecraft. The shuttle's pressure is lowered in preparation for tomorrow's spacewalk.

1409 GMT (10:09 a.m. EDT)

The extension ring on the shuttle's docking system is being retracted, bringing the international space station's docking port to a firm seal with Endeavour. The seven astronauts aboard Endeavour and the three-person space station Expedition Two crew are now orbiting together in a single, joined spacecraft.

1400 GMT (10:00 a.m. EDT)

Mission Control reports the docking occurred 243 miles above the South Pacific Ocean southeast of New Zealand. Currently, the rates between the shuttle and station are being damped out. Later the hooks and latches will be closed to firmly join the two spacecraft and Endeavour's Orbiter Docking System docking ring will be retracted.

1359 GMT (9:59 a.m. EDT)

CONTACT AND CAPTURE! Space shuttle Endeavour has docked to the international space station for a week-long visit. Endeavour brings with it the Canadarm2 robotic space crane to be attached to the station during a spacewalk tomorrow, and the Italian Raffaello cargo module that will deliver food, supplies, equipment and experiments to the orbiting outpost.

1358 GMT (9:58 a.m. EDT)

Five feet to docking. The orientation-control gyros on the station are disabled for the linkup while Endeavour's thrusters are programmed to fire in a calculated way to force the two docking ports together at the point of contact.

1357 GMT (9:57 a.m. EDT)

Distance is now 10 feet as Endeavour slowly inches ever closer to the international space station under the manual control of commander Kent Rominger, who will become the first shuttle commander to make two link ups with the new outpost.

1355 GMT (9:55 a.m. EDT)

Now 20 feet to docking.

1353 GMT (9:53 a.m. EDT)

The alignment between docking ports on Endeavour and the space station is acceptable and no "fly out" maneuver by the shuttle is necessary. The final approach along the last 30 feet is now in progress.

1350 GMT (9:50 a.m. EDT)

Endeavour is now 50 feet from the space station, closing at a rate of 0.09-feet per second.

1345 GMT (9:45 a.m. EDT)

Distance now 75 feet.

1341 GMT (9:41 a.m. EDT)

Now 100 feet separating Endeavour from the station. Closure rate is 0.08 feet per second.

In a pre-flight interview, commander Kent Rominger described how this rendezvous and docking would unfold. Here it is:

"The docking on this flight is a profile that's going to be used for years and years to come. However, we're only the second shuttle that's going to actually do this type of profile. But, it's interesting in that, on my last flight, we came up from below the station and then flew around to the top and came down from the top and docked. This one is similar in that we come up from below initially into about 500 feet, and then we fly the space shuttle around a 90-degree arc and then come in along the velocity arc. The arc that the station is traveling along and we're both going over 17,000 miles an hour. And, now we close along, right along that velocity vector.

"The things that are different about it [are] due to orbital mechanics. Because we're closing along the velocity vector of the station, we don't really have any natural braking. So, it's a little more critical down at this point where we initiate this maneuver to come up that we hit these parameters right. If we don't, then we can be too fast coming in; and which is not a real big problem other than that we have to brake. And, because we don't want to fire our thrusters at the space station and damage some of the arrays, we have a mode where the thrusters fly mostly up, fire mostly up and down but it's pretty inefficient. It costs almost 10 times as much fuel to brake that way as it does the normal way. But, that's what we have to do so we don't damage it.

"So, we try to avoid that type of braking. And, that's the trickier part. We can do it. If we have to do too much braking, it takes a lot of fuel and then we may lose something like a reboost that, you know, we wouldn't have the fuel for a later task."

1334 GMT (9:34 a.m. EDT)

The docking time will be pushed back further as Endeavour's slow approach is taking a bit longer that originally slated. Distance between the craft is less than 140 feet. Mission Control has not announced a new targeted docking time, but the link up is probably about a half-hour away.

1330 GMT (9:30 a.m. EDT)

Distance separating the two craft now 175 feet as they move into orbital darkness.

1326 GMT (9:26 a.m. EDT)

Endeavour is now 200 feet from the space station, closing at a rate of 0.14-feet per second.

1320 GMT (9:20 a.m. EDT)

Distance now 250 feet.

1318 GMT (9:18 a.m. EDT)

Endeavour and the space station are now about 295 feet apart, closing at about two-tenths of a foot per second as commander Kent Rominger begins the push to docking.

1314 GMT (9:14 a.m. EDT)

Endeavour has now reached the velocity vector, or V-bar, directly in front of the station's direction of travel with a distance of about 300 feet. The shuttle will hold at this point for about five minutes for a stationkeeping maneuver to ensure proper alignment between the two craft before the approach to docking begins.

1311 GMT (9:11 a.m. EDT)

Mission specialist Scott Parazynski is now powering up Endeavour's Orbiter Docking System in preparation for the link up, which is now 28 minutes away.

1304 GMT (9:04 a.m. EDT)

Endeavour is about half-way along its trek from a point below to the point in front of the space station. The relative distance between the two craft is about 400 feet.

1300 GMT (9:00 a.m. EDT)

The U.S. solar arrays on the space station -- stretching 240 feet tip-to-tip -- are being feathered to an "edge-on" position relative to Endeavour's final approach to the front side of the station in the next hour. This is done so the thruster plumes from Endeavour don't harm the delicate arrays.

The Russian solar arrays on Zarya and Zvezda will be repositioned shortly.

1259 GMT (8:59 a.m. EDT)

After stopping the shuttle's closing motion from below, Rominger is now beginning quarter-circle flyaround to position Endeavour directly in front of the station.

1254 GMT (8:54 a.m. EDT)

Endeavour has now reached that milestone point 600 feet below the space station.

Shuttle commander Kent Rominger is taking over manual control for the remainder of today's rendezvous and docking of Endeavour to the international space station. This is Rominger's second docking with the station following his first visit in May 1999. He will become the first commander to dock twice with the station.

Piloting the shuttle from the aft control station on the flight deck of Endeavour, he will regularly pulse the shuttle's steering jets to keep the shuttle on the correct course.

1250 GMT (8:50 a.m. EDT)

Distance between the two craft is 850 feet, with Endeavour closing at a rate of 1.2 feet per second. Once reaching a point 600 directly beneath the station, Endeavour will begin moving in a quarter-lap flyaround to the front of the station for alignment with the docking port on the U.S. Destiny lab.

1241 GMT (8:41 a.m. EDT)

The last in a series of four course correction maneuvers by Endeavour's steering jets has been performed. The shuttle is on a trajectory to reach the station for docking at 9:39 a.m. EDT.

1239 GMT (8:39 a.m. EDT)

Now one hour away from the docking. Endeavour is about a half-mile below the station.

1232 GMT (8:32 a.m. EDT)

The third of four course corrections now complete. Distance between the two craft is 4,000 feet, with Endeavour closing at a rate of five feet per second.

1227 GMT (8:27 a.m. EDT)

NASA reports the overall docking timeline is being refined and the physical link up between Endeavour and the international space station is now expected at 9:39 a.m. EDT.

There is not any constraint about when the docking occurs. Unlike previous missions, the docking is not required to take place while in coverage of Russian ground stations.

1215 GMT (8:15 a.m. EDT)

The second course correction maneuver has been performed in this final phase of Endeavour's rendezvous with the space station. This was a 10-second pulse of the steering jets. The shuttle is currently 11,600 feet away from the station, closing at about 10 feet per second.

1200 GMT (8:00 a.m. EDT)

Endeavour is now four miles from the international space station, just over 90 minutes to docking.

1140 GMT (7:40 a.m. EDT)

Endeavour has performed a five-second pulse of its steering jets -- the first of four small maneuvers to tweak the shuttle's trek to the international space station.

The Endeavour is about 7 miles behind and below the station. In about an hour, Endeavour will reach a point less than 600 feet directly below the station where Endeavour will begin a maneuver to fly to a point 300 feet in front ISS for the final approach to docking with the Destiny lab module. The docking is scheduled for 9:32 a.m. EDT while the two craft are cruising 240 miles overhead the Southeast coast of China, northeast of Victoria, Hong Kong, NASA reports.

Meanwhile, the station has been maneuvered to the proper docking attitude and the giant U.S. solar wings are being feathered to an edge-on so the shuttle's thruster plumes don't damage the arrays during final approach.

1120 GMT (7:20 a.m. EDT)

Trailing the international space station by about nine statute miles, shuttle commander Kent Rominger fired Endeavour's maneuvering jets at 7:18 a.m. EDT for 13 seconds to begin the terminal phase of today's rendezvous. If all goes well, Rominger will guide the shuttle to a linkup with the station's forward PMA-2 docking port at 9:32 a.m.

There are no technical problems of any significance with the shuttle, but engineers are still scratching their heads over the status of a carbon dioxide removal system in the station's Russian command module, Zvezda. The Vozdukh system was only working at half power Friday and the crew planned to troubleshoot the system early today.

But a NASA spokesman said engineers reported the device apparently resumed normal, full-power operation on its own today. As of this writing, it's not yet clear what was wrong or what happened to correct the problem.

The Vozdukh's performance was not an issue for Endeavour's docking because the shuttle's air scrubber can easily compensate for low output from the Russian system. But flight controllers wanted to fix the problem before arrival of a Russian Soyuz spacecraft April 30 carrying U.S. businessman Dennis Tito and two crewmates.

Working at half power, the Vozdukh would not have been able to handle the load of the increased six-member crew, forcing them to tap into the station's limited supply of CO2-absorbing lithium hydroxide canisters. While that's not a problem in and of itself, flight controllers naturally want to reserve the lithium hydroxide supply for emergency use only.

Assuming the Vozdukh stays healthy, that will not be an issue.

Today's flight plan calls for Rominger to approach the station from behind and below, looping up directly in front of the outpost before beginning the final push to dock.

The shuttle should be positioned 600 feet directly below the station at 8:48 a.m. At that point, Rominger will initiate a pitch maneuver as he loops up in front of the station, arriving on the so-called velocity vector 310 feet directly ahead of the outpost at 9:02 a.m. The shuttle will be oriented with its tail facing Earth and its cargo bay facing the station.

Rominger will briefly halt Endeavour's approach at a distance of 30 feet or so to ensure communications coverage through NASA's western Tracking and Data Relay System satellite. The final push to dock should begin at 9:26 a.m. for a linkup at 9:32 a.m.

The station currently is made up of four pressurized modules connected end to end. NASA's Destiny laboratory module is bolted to the multi-hatch Unity node. Unity, in turn, is connected to the Russian-built NASA-financed Zarya module, which is attached to the Russian Zvezda command module. Unity's port hatch is occupied by a spare shuttle docking port while its starboard hatch is vacant. Unity's upward-facing port is occupied by a boxy structural truss that houses the station's four stabilizing gyroscopes. Bolted to the top of the Z1 truss is the huge P6 solar array, which provides most of the station's electrical power. The two panels making up the P6 array stretch 240 feet from tip to tip, oriented like two huge wings at right angles to the long axis of the station.

Endeavour will dock at a pressurized mating adapter - PMA-2 - on the front end of the Destiny module. But the crew will not actually enter the station for the first time until after a spacewalk Sunday by Chris Hadfield and Scott Parazynski to install the new Canadarm 2 space crane on the hull of the Destiny module.

To help the spacewalkers purge nitrogen from their bloodstreams, the shuttle's cabin air pressure was lowered from its normal 14.7 pounds per square inch to 10.2 psi Friday. The station's pressure remains at 14.7 psi, precluding the crews from opening hatches between the spacecraft today.

Instead, Endeavour's astronauts will limit their activities to PMA-2, opening the docking port tunnel, stowing equipment the station crew needs and then resealing the hatch. The station crew then will enter PMA-2 and retrieve the equipment, using the docking port as an airlock.

Read our earlier status center coverage.