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kl90

Shuttle, Atlas Press Toward Weekend Launches


Shuttle Discovery's launch pad at Kennedy Space Center will reeopen this afternoon and NASA managers will meet late today to set a course of action for troubleshooting work the agency hopes will lead to a launch attempt Sunday.

The U.S. Air Force and United Launch Alliance, meanwhile, are continuing to step toward an already scheduled Saturday night launch of an Atlas V rocket with a new-generation military communications satellite.

But ULA is willing to forego their launch opportunity Saturday if NASA can put itself in position to pick up a countdown and try to send up Discovery and seven astronauts at 7:43 p.m. Sunday.

"We're pressing ahead with preparations to launch on Saturday. But there's not a national imperative that we launch on that day, so we can adjust," said ULA spokesman Mike Rein.

As it stands, an Atlas V and its payload -- a Wideband Global SATCOM spacecraft -- are scheduled to blast off from Launch Complex 41 at Cape Canaveral Air Force Station at 9:25 p.m. Saturday. The launch window that night will extend until 10:03 p.m.

NASA is facing a Tuesday deadline to launch Discovery. After that, the agency would have to stand down for an already scheduled crew rotation and change-of-command at the International Space Station. In that case, the Discovery launch would be pushed back to about April 7.

If NASA presses ahead with a launch attempt Sunday, then the Atlas launch would be postponed until the middle of next week.

The reason: It typically takes about 48 hours to reset Eastern Range tracking and range safety systems between the launches of different vehicles flying different flight profiles. Range users typically are allowed a back-up launch date in case weather or a minor technical problem prompts a scrub.

So NASA would be allotted launch attempts on Sunday and Monday, and in this case, the agency probably would be given an opportunity on Tuesday if need be. The earliest the Atlas could launch then would be next Wednesday or Thursday.

An initial attempt to launch Discovery on Wednesday was scrapped when a gaseous hydrogen leak was detected near the end of fuel-loading operations.

The leak was traced to a quick-disconnect valve that links a gaseous hydrogen vent line with the shuttle's external tank. The vent line is designed to route excess gaseous hydrogen from the liquid hydrogen tank within the ET to a flare stack in the pad 39A area. The flare stack burns off the hydrogen.

NASA drained the external tank Wednesday and the pad will be reopened about 3 p.m. this afternoon. Technicians with United Space Alliance then will extend a work platform from the Fixed Service Structure at the pad to the area where the leaking gaseous hydrogen line connects to the tank's Gaseous Umbilical Carrier Plate. The suspect quick-disconnect valve links the gaseous hydrogen line and the carrier plate. Scaffolding then will have to be built up on the extended work platform to emable technicians to reach the valve.

The general plan calls for technicians to remove the valve so that it can be inspected. Of paricular interest will be two seals within the valve. The seals might be the source of the leak. Or the quick-disconnect valve might be misaligned.

NASA mission managers will meet at 4 p.m. to go over a more refined troubleshooting plan. Once the plan is okayed, then the technicians will begin the troubleshooting work. NASA will reveiew the results of the troubleshooting work and decide Friday whether to press ahead with a launch attempt Sunday.

kl90

Station Crew Shelters From Approaching Debris
Blogger update, 1:05 p.m.: The small piece of space debris that threatened the International Space Station crew has passed without incident, NASA has confirmed.

The crew is exiting the Soyuz spacecraft, opening U.S. hatches and returning to normal duties. They were given the all clear at 12:45 p.m. EDT.

The crew of the International Space Station will be taking shelter in a Soyuz lifeboat in case an approaching piece of space debris strikes the orbiting outpost.

Station skipper Mike Fincke and flight engineers Yury Lonchakov and Sandra Magnus will remain in the Soyuz until the debris from a spent U.S. upper stage motor passes by the outpost at 12:37 p.m. EDT. The debris is about one-third-of-an-inch in diameter. Traveling seven times the speed of a rifle bullet, it could cause significant damage if it strikes the hull of the outpost.

The debris is expected to pass about 4.5 kilometers from the station, and the shletering is a precautionary measure. The crew would be ready to abandon ship if the debris for some reason struck the station and caused a decompression.

The piece was spotted approaching the area of the station late Wednesday. The crew sealed the U.S. segment of the outpost. The decision to shelter was made because it was deemed too late to execute a collision-avoidance maneuver.

kl90

Shuttle Launch Reset for Sunday
Shuttle Discovery and seven astronauts will attempt to launch from Kennedy Space Center at 7:43 p.m. Sunday, NASA officials announced this morning.

The decision delays Saturday's planned launch of a United Launch Alliance Atlas V rocket with a military communications satellite payload until next week.

The Atlas V launch now is tentatively targeted for 9:24 p.m. Tuesday from Cape Canaveral Air Force Station.

Engineers have not yet determined what caused a valve to leak hydrogen gas on Wednesday during fueling of Discovery's orange external tank, an issue that forced managers to scrub the mission's first launch attempt that day.

"We don't have any smoking guns yet," said Mike Leinbach, NASA's shuttle launch director, during a briefing this morning at KSC.

He said it wouldn't be clear if a repair that technicians are working on today is successful until reaching the same point during fueling on Sunday, which is set to begin at 10:18 a.m.

Technicians are working to replace a quick-disconnect device that includes a seven-inch diameter valve. The device is part of a line that vents hydrogen gas from the external tank to a stack of flares on the ground.

That helps maintain proper pressure in the tank during fueling of super-cold liquid hydrogen.

Tests of the valve using helium at room temperature show no problems, Leinbach said, so it appears that the transition to extreme cold is causing the problem.

With a successful launch on Sunday, Discovery would embark on a slightly shortened mission to the International Space Station. The mission would last 13 days instead of 14, and the last of four planned spacewalks would be dropped.

That's because NASA needs to leave the station before the planned March 26 launch of a Russian Soyuz spacecraft carrying three new station crew members.

If Discovery can't launch by Tuesday, it would have to wait until April 7.

The crew will attempt to complete the space station's power supply by adding a final set of power-generating solar array wings. The wings are packed on the 11th and final piece of the station's truss, or backbone, which will measure 335 feet when complete.

The weather forecast for Sunday is good, with an 80 percent chance of conditions allowing a launch.

Conditions worsen after Sunday, with a 70 percent chance of good weather Monday but only a 40 percent chance on Tuesday.

kl90

Shuttle, crew safely reach orbit

Discovery and seven astronauts are safely in orbit.

Nine minutes after lifting off from the Kennedy Space Center, the orbiter and its crew have just dropped the external tank and they are drifting.

The shuttle lifted off under skies so clear that the twin solid rocket boosters could be seen falling away. As the shuttle climbed higher, viewers back at KSC could see its plume turn orange as sunlight reflected off of it.

The crew immediately got working on its initial post-launch checklists, working with Mission Control in Houston to do the work to prepare Discovery for almost two weeks in orbit.

[ 本帖最后由 kl90 于 16-3-2009 09:41 AM 编辑 ]

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Astronauts begin mission's work

Commander Lee Archambault and his crew have begun orbital operations after a stunning, colorful twilight liftoff from the Kennedy Space Center.

A stowaway bat and a minor technical glitch were the only hiccups in an otherwise smooth countdown, following several days of hurried work to repair a leaking valve that forced NASA to call off the first launch attempt on Wednesday night.

Ahead for the crew is the inspection of its heat-shielding tomorrow, followed by docking at the International Space Station on Tuesday. The first spacewalk of the flight comes on Thursday.

Their mission: installing the last piece of the space station's central truss and a final set of solar arrays. That will clear the way for the expansion of the permanent space station crew from three to six people.

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Space shuttle Discovery blasts off with crew of 7

CAPE CANAVERAL, Fla. – Space shuttle Discovery and its crew of seven rocketed into orbit Sunday evening, setting off on a space station construction mission cut short by launch delays that dragged on for more than a month.

The launch, though late, turned out to be flawless and the prettiest NASA managers had ever seen.

Discovery rose from its seaside pad just as the sun was setting, an especially spectacular sight for a space agency anxious to get the flight going. As the shuttle sped away like a brilliant star, the upper part of the launch plume glowed pink, peach and golden.

Launch controllers could see the shuttle for seven minutes, until it reached somewhere off the New York or New Jersey coast. "We were all rewarded with a beautiful, beautiful launch," said launch director Mike Leinbach.

A hydrogen leak prevented Discovery from lifting off Wednesday and, before that, hydrogen valves kept the shuttle grounded for weeks in February. Launch pad repairs took care of the leak, and the astronauts were able to board their spaceship and lift off.

"Well, you had a little bit of a wait but that will just make the payoff that much sweeter," Leinbach told the astronauts.

Commander Lee Archambault and his crew, which includes two former schoolteachers, should reach the international space station Tuesday. They're delivering one last set of solar wings for the orbiting outpost and some critical equipment for a relatively new water-recycling system.

"We'll see you in a couple weeks," Archambault radioed.

No one was more eager to see Discovery take off than the three space station astronauts. Commander Mike Fincke was ecstatic when informed nothing was leaking at the pad.

"That is most excellent news," Fincke told Mission Control. "That's exactly what's been on top of our minds."

During Wednesday's try, hydrogen gas spewed into the air from a vent line connected to Discovery's external fuel tank. NASA replaced the hookups, but could find nothing broken.

The system remained tight during the countdown, and the only problem was a pressure drop in a helium-purge system that workers quickly resolved.

The only other oddity was a fruit bat on the back of Discovery's fuel tank that posed no debris threat to the shuttle and almost certainly perished.

The four-day leak delay forced NASA to shorten Discovery's flight by a day and cut out a spacewalk. Because of a Russian Soyuz rocket launch March 26, Discovery needs to be gone from the space station by the time that spacecraft flies. The Soyuz will carry up a fresh crew for the space station.

Discovery's mission will last 13 days and feature three spacewalks instead of four, the first of which will take place Thursday to install the new solar wings. The two wings will join six already in place and bring the orbiting outpost up to full power.

The canceled spacewalk chores will be tackled by the space station crew after Discovery leaves. Mike Moses, chairman of the mission management team, estimated 80 percent to 90 percent of the mission will still be accomplished, despite the shortened flight.

Discovery also will deliver a spare urine-into-drinking water converter to replace one that's broken, and a flusher and iodine solution to get rid of bacteria that's lurking in the water dispenser.

NASA wants to double the size of the space station crew to six people by the end of May, and need the recycled water to drink.

Discovery originally was supposed to lift off Feb. 12, but NASA ordered extra tests for the valves that control the flow of hydrogen gas into the fuel tank. The three valves in the shuttle's engine compartment kept being replaced to ensure they were the best available and safe to fly.

One of these valves — which maintain tank pressure during liftoff — broke during the last shuttle launch in November. No harm was done, but NASA did not want to take any chances with Discovery.

NASA said the valves seemed to work well during Wednesday's liftoff.

Late Sunday, Mission Control informed the astronauts that although the launch video was still being analyzed, no significant piece of debris appeared to strike the space shuttle.

Two educator astronauts are aboard Discovery: Joseph Acaba and Richard Arnold II, chosen by NASA five years ago. There also is one Japanese astronaut, Koichi Wakata, who will move into the space station for at least three months, replacing one of the current crew.

kl90

STS-119 LIVE: Discovery launches - perfect count and ride to orbit
March 15th, 2009 by Chris Bergin

STS-119 has launched after an issue-free tanking and countdown, following engineering work to troubleshoot a LH2 (GH2) leak from the Ground Umbilical Carrier Plate (GUCP) attached to the External Tank. Discovery launched at 19:43pm local time launch, with added focus on the T-0 umbilicals on the TSM (Tail Service Masts) - following an incident on STS-126.

Leak checks were completed overnight, as the Rotating Service Structure (RSS) was retracted to reveal a floodlit Discovery on Pad 39A. Work was behind schedule, due to slight issues with the left and right GUCP (Ground Umbilical Carrier Plate) pivot assembly.

“Discovered the GUCP was not aligned properly with the external tank,” engineering notes confirmed. “The left and right pivot seat was not fully connecting to the external tank’s pin receptacle sleeve at the bottom of the GUCP.”

Troubleshooting has been taking place on the GUCP following a red line leak from the hardware when the tank reached around 98 percent full on Wednesday.

See Also

    * STS-119 LIVE UPDATES
    * L2 STS-119 LIVE (MMT Level)
    * Click here to Join L2

No “smoking gun” has been found on the root cause of the issue, though the changeout of seals and components, ahead of re-attachment and re-torquing a tight fit on the seal, is believed to be sufficient for ensuring the problem does not reoccur.

“There was some damage to the flight seal, but we’re not sure that’s the cause,” noted launch director Mike Leinbach. “There was a bit of discoloration on the QD (Quick Disconnect), but that might have been to the hydrogen flowing where it shouldn’t have been. If it doesn’t leak, we’ll be perfectly fine to launch.

“The discoloration was on a surface inside the QD, and we’re 99 percent positive we didn’t have LH2 (inside), we’re sure we had GH2 in there.

“We like to find what is wrong, and especially with this, as it was a healthy leak. We’ll go study the system, and see what is up. (However,) from a crew safety standpoint, we’re perfectly fine.”

At one point engineers were deemed to be eight hours down on the timeline, which was at least halved by the time second shift started work on Saturday evening.

Flexibility exists in the timeline for the commencement of tanking - if had it been required. However, tanking started on schedule, with the first test of the Engine Cut Off (ECO) sensors providing expected results. The SIM test also was issue-free.

Importantly, tanking suffered from now tripped leak detector’s, a sign the new seal on the GUCP worked as required.

The only “concern” was a bat, which was seen hanging from the -Z side of the tank. Another bat had to be saved by engineers after falling into the water bags at the foot of the SRBs.

The STS-119 crew ingressed into Discovery, hatches were closed, and no issues were work ahead of a spectacular launch, which has been classed as issue-free via early results.

STS-119 is now into Flight Day 1, ahead of opening inspections on Flight Day 2 via the OBSS (Orbiter Boom Sensor System).

kl90

TSM T-0 focus:

While all the recent engineering work has been on issues such as the Flow Control Valves (FCVs) and the GUCP issue, the lessons learned from previous flights - and their resulting get-wells - once again portrays the multi-element focus on ensuring a safe launch.

One such threat to a “clean” launch is ice, usually liberating from the External Tank (ET), with a similar potential risk to the orbiter’s Thermal Protection System (TPS) as foam liberation.

While amazing progress has been made on the highly complex issue of foam liberation, a “new” ice threat was observed on STS-126, via a build up on the T-0 umbilical plate mated to Endeavour.

The T-0 umbilical - located on each side of the orbiter - is mated to the orbiter via retractable plates in the Tail Service Masts (TSMs), which can be seen either side of the orbiter’s aft. These umbilicals are retracted at SRB (Solid Rocket Booster) ignition.

Via engineering camera views from inside the TSM, ice was seen to have developed on the carrier plate of the LH2 umbilical during tanking. Obscured by view until lift off, the ice then remained with the orbiter, before liberating 26 seconds later, thus becoming a debris threat. On this occasion, the ice avoided impact with the vehicle.

his led to an engineering investigation into the issue, its risks, and a forward plan on mitigating that risk, resulting in five large presentations being created for the Program Requirements Control Board (PRCB) earlier this year.

All five presentations and the 330mb engineering super slow mo camera “all views” video are available on L2.

“Problem Description: At 26.696 MET (Mission Elapsed Time), debris was observed to liberate between the LH2 T-0 umbilical and port OMS pod,” noted one overview presentation on L2.

“Real-time observations of focused inspection using OBSS (Orbiter Boom Sensor System) on Flight Day 2 did not show any apparent residual damage or artifacts.

“Review of the 16MM film camera (E22) on the MLP (Mobile Launch Platform) has identified an ice build-up in this location. This has been identified as the object observed liberating.”

As part of the investigation, the KSC Imagery Assessment Team (IAT) reviewed imagery from 119 missions and concluded that frost/ice had formed in the LH2 T-0 seal area on seven missions (STS-62, 87, 108, 111, 116, 123 and 126).

However, STS-126 is only known launch to have liberated ice/frost from LH2 T-0 Umbilical area post T-0. There are no known releases from the LO2 umbilical on the opposite side of the vehicle.

To gain a full understanding of the historical database on ice build-up in this location, images were shown in one presentation of every TSM camera view of each of the aforementioned launch.

NASA engineers have such a vast database available for every flight back to STS-1.

“LH2 T-0 Umbilical Findings: KSC Image Analysis Team (IAT) reviewed imagery from camera E022 (located inside the LH2 TSM) for 119 additional missions for ice/frost build up on the Orbiter LH2 T-0 Umbilical during T-0 retraction.

“Ice/frost had formed on the LH2 T-0 seal area on 6 other missions: STS-62, 87, 108, 111, 116, and 123.

“6 additional occurrences of ice/frost were found on the interior plate surface (away from the seal perimeter).  All of these occurrences were prior to STS-26R.  Mainly small formations around the main LH2 line.  Redesigns appear to have fixed the problem as it does not appear again.

“LO2 T-0 Umbilical Findings: KSC IAT reviewed imagery from camera E021 (located inside the LO2 TSM) for 116 additional missions for ice/frost build up on the Orbiter LO2 T-0 Umbilical during T-0 retraction.

“Vapors from the LO2 T-0 Umbilical area have the opportunity to obscure much of the view.  61 missions had a good view around the vapors with good exposure. Ice/frost had formed on the Orbiter LO2 T-0 plate on 9 mission: STS-8, 11, 52, 90, 92, 36, 38, 109 and 110.”

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The reason for the ice build-up itself is believed to be caused by a combination of factors, ranging from the design of the TSM to water intrusion into the hardware.

“Due to the design of the T-0 umbilical, ice formation internal to the cavity is possible,” added the overview presentation. “Leading theory is cold temperature in combination with low delta pressure to ambient, along with potential water intrusion from rain or condensation, is allowing moisture intrusion into umbilical cavity resulting in ice formation.

“Material Analysis lab seal test results indicate some degradation of seal material properties, however, design requirements are being met.”

Given debris threats are taken very seriously, a risk acceptance presentation was created by Space Shuttle Systems Engineering and Integration Office (SE&I) on the subject of Probabilistic Risk Assessment (PRA) and Debris Transport, to further understand the threats to both the aft of the orbiter and SRBs.

While “potential risk is to Ascent, Re-entry, and for Structural Damage to the Orbiter,” was calculated by the worst case liberations (in mass) via four simulations ranging from 0.1 to 2.8 lbms of ice, the design of the orbiter provides an element of shielding to several critical area of flight hardware.

“OMS Nozzle and SSMEs are entirely shielded by the OMS Pod and the Fuselage for every Mach/mass combination,” noted the SE&I presentation. “The Body Flap and the Orbiter Base are somewhat shielded by the OMS Pod and the Fuselage, thus reducing their risk.

“The Body Flap and the Elevons are far enough away from most trajectories that a majority of the dprox cones do not impact them. L (left) SRB Aft Skirt has a low risk of impact due to the distance from the release points. Fuselage Side and OMS Pod are the areas of highest risk for all masses.

“For a release rate of one per flight, the largest mass, mass 2.7931 lbm, has the highest risk for every component: 1 in 47 probability of impacting the Fuselage Side. 1 in 82 probability of impacting the OMS Pod.

“Lowest risk for every mass to the OMS Pod or Side Fuselage is 1 in 1100 which corresponds to the smallest mass, 0.1020 lbm. Release rate is a driver to the risk.”

In conclusion to SE&I’s 35 page presentation, only high mass liberations of ice are to be deemed as a viable risk to causing damage to orbiter or SRB - specifically the Booster Separation Motors) - during ascent, should the liberation manage to hit the vehicle in the first place.

“Ice from perimeter of LH2 T-0 Umbilical has transport mechanism to Orbiter Side Fuselage, OMS, and RSRB. Other Orbiter Components are shielded enough that they have a low risk of impact for any of the masses analyzed.

“Impact (potential) on Orbiter limited to Side Fuselage, OMS Pods, Elevons, and edge of Orbiter base and Body Flap. No impact (potential) on SSME or OMS nozzles were sustained due to shielding provided by side fuselage and OMS.

“Impacts on RSRB occur at Inboard Side Aft Skirt at higher masses only. Maximum energy impacts occur at Mach 1 or Mach 1.26. Impacts with ice of mass 2.8 lbm (largest analyzed) can result in impact KE of 2563 ft-lbf on Orbiter and 2838 ft-lbf on RSRB Aft Skirt.

“Impacts with ice of mass 0.1020 lbm (smallest analyzed) can result in impact KE of 142 ft-lbf on Orbiter and does not impact RSRB Aft Skirt. Aft BSMs show low risk. Specific regions of higher concern have lower risk than overall PRA.

“In general, most forward release locations result in largest impact energy. STS-126 is the only documented release & mass was conservatively estimated 0.83 lbm. There has been no damage attributable to a T-0 ice release.”

Despite the low risk, KSC engineers inspected the TSMs and T-0 umbilical plates that are being used on STS-119’s launch for any issues with their seals and components.

“STS-119 Mitigations: STS-119/MLP-1 internal can seals were inspected prior to T-0 mate and verified to be free of defects,” noted the United Space Alliance (USA) presentation. “Post mate to orbiter and prior to peripheral seal installation, the visible portions of the internal can seals were inspected and verified to have positive contact to orbiter.

“Peripheral seal was inspected prior to installation and verified free of defects. Peripheral seal was inspected post installation in VAB and verified free of gaps. Peripheral seal was inspected post rollout to pad and verified no change in configuration.

“STS-126/MLP-3 internal can seals and peripheral seal were inspected post flight with no defects or degradation noted. MLP-3 post launch and MLP-1 pre-orbiter mate OMRS purge tests performed with no anomalies reported.

“T-0 Umbilical Seal was verified by a KSC Materials Lab test to comply with the procurement specification. Results indicate minor degradation of seal material properties over time but seal still capable of meeting design intent. GN2 trickle purge activated post rollout. He purge activated 7 hours prior to cryo load.”

a6USA also worked on a “rain diverter” which has been added to the TSMs for STS-119, as a form of extra protection from one of the determined drivers of ice formation on the T-0 umbilical area.

“Design and Install a Rain Diverter - KSC ERB (Engineering Review Board) approved Rain Diverter installation for STS-119 on LH2 and LO2 Umbilicals on 01-23-09. OPO (Orbiter Project Office) and SE&I concur with installation.

Also noted in the presentations is the ability to apply a release agent to the T-0 umbilical plates, which would allow for a fast release of any ice build-up, before the vehicle reaches velocities that would allow the ice to become a debris threat on impact with orbiter hardware.

However, no information on the release agent’s approval for STS-119 was noted on processing notes during the run up to STS-119’s launch countdown.

“Application of release-agent to the Orbiter T-0 Umbilical plate: OPO, Boeing Design, M&P and SE&I are evaluating the possibility of applying a release-agent to the Orbiter T-0 Umbilical plate.

“OPO agrees may be beneficial to mitigating ice adhesion but requires compatibility assessment and approval by all disciplines prior to installation. Development of application procedure required.”

As the ultimate back-up to ensuring no damage has been caused by any ice that may build-up on Discovery’s T-0 umbilical plates, special attention will be focused on the area of the orbiter during ascent via long range telescopic cameras and on orbit inspections (Flight Day’s 2 and 3).

However, given the mitigation procedures carried out on STS-119, and the historical lack of flights bar STS-126 that have seen ice liberate during first stage from this area of the vehicle, the issue is unlikely to be noted again over the remaining flights of the shuttle.

kl90

Special report on shuttle's final 10 missions
Todd Halvorson offered readers a special report last week in the FLORIDA TODAY newspaper, detailing the challenges facing NASA as the space agency attempts to fly as many as 10 space shuttle missions before the end of next year.
http://floridatoday.com/article/20090311/NEWS02/903110322

And, you should also check out this graphic laying out the basics of each of the remaining 10 missions of the space shuttle fleet.http://www.floridatoday.com/assets/pdf/A9130177311.PDF

kl90

Discovery Flip Complete; Orbiter "Clean"
Discovery has completed its backflip maneuver and is "go" for docking with the International Space Station.
Check out the amazing sequence of photos showing the nine-minute backflip, or Rendezvous Pitch Maneuver, just 600 feet below the station.
Despite communication problems, station astronauts Mike Fincke and Sandra Magnus shot up to 300 pictures of the orbiter's heat shields, using digital cameras with 400 millimeter and 800 millimeter lenses.

Fincke said the shuttle "looked clean, very nice," from his vantage point in the Russian Zvezda service module.

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Discovery Docked!
Shuttle Discovery docked with the International Space Station at 5:19 p.m., completing a two-day chase that began with the shuttle's launch Sunday evening from Kennedy Space Center.

"Capture confirmed," shuttle commander Lee Archambault told mission controllers in Houston, as the orbiter and station crossed over western Australia.

"Welcome to the space station, Discovery, we're glad you're here," station skipper Mike Fincke said.

"Glad we're here also," Archambault said.

After the initial contact, several more steps are required to make final connections between the spaceships and make sure their alignment is good.

It will be more than an hour before leaks checks and airlock pressurization are complete, and hatches separating the two vehicles is opened.

The seven shuttle astronauts and three station residents will then hold a formal welcome ceremony

kl90

Discovery, Station Crews Meet
Three International Space Station residents greeted Discovery's seven astronauts with hugs and handshakes as they climbed through an airlock just after 7 p.m.

"Space shuttle Discovery arriving," station flight engineer Sandra Magnus called out while ringing a bell.

"Welcome aboard our beautiful International Space Station," said Mike Fincke, the leader of the station's Expedition 18 crew. "We're dang glad you're here."

"We've got a lot of work to do," said shuttle commander Lee Archambault. "We're looking forward to it, but this is a very special moment. Thanks for having us aboard."

"So, let's get to work," said Fincke.

The joint teams immediately began a standard safety briefing.

Within the hour, Magnus was scheduled to officially hand over her post on the station to Japanese astronaut Koichi Wakata, who flew up with Discovery.

That happens when Magnus removes her customized seat liner from the Russian Soyuz spacecraft that would serve as the station's escape vehicle in an emergency.

Wakata will transfer his seat liner from the shuttle to the Soyuz and become a member of Expedition 18. He's expected to stay in orbit, during which time he'll transition to another crew: Expedition 19.

In addition to transfering the seat liners, crew members will begin transfering some cargo and two spacesuits scheduled to get their first use on Thursday during the first of three planned spacewalks.

NASA managers described today's shuttle docking as extremely smooth, reporting no technical problems.

"I can't think of any one I've had in recent memory that went that smooth," said Paul Dye, lead shuttle flight director.

kl90

Posey: Obama should name NASA chief soon
FLORIDA TODAY's EUN KYUNG KIM reports from Washington:

Rep. Bill Posey is urging President Barack Obama to name a new agency chief as soon as possible, saying NASA "cannot afford to remain without an administrator at this critical juncture."

The Rockledge Republican sits on the NASA House Action Team, co-chaired by Rep. Suzanne Kosmas.

"Major decisions are being made that will greatly affect our nation's future in space," Posey wrote. "NASA is in the midst of making decisions about the phasing-out of the Shuttle program and how we move forward with America's next generation launch vehicle."

"If this transition is not done right, not only will thousands of American workers at the nation's space centers and their families be severely and adversely affected, but our nation's leadership in space will further erode," he wrote.

"As budget decisions are being made, it is vital to have someone sitting at the table that is knowledgeable about space and is looking out for the agency's future," Posey wrote. "I am also concerned that further delay in appointing an Administrator may lead some to conclude that space policy and our nationâ

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Atlas Delay At Least 48 Hours

Launch of an Atlas V rocket and a new-generation military communications satellite is being delayed until at least Friday to give engineers time to investigate the failure of an upper stage engine valve.

The 19-story rocket and its payload -- a Wideband Global SATCOM spacecraft -- had been slated to blast off from Launch Complex 41 at Cape Canaveral Air Force Station at 9:24 p.m.

But a valve in the rocket's single Centaur upper stage engine sprang a leak about 20 minutes into fuel-loading operations. The leak was serious enough to prompt mission managers to immediately call a scrub.

Engineers estimate that it will take most of the night to drain propellant from the Centaur stage and then inert it to make certain no explosive gases remain within it.

The course of action likely will be to remove a box within the engine that holds the valve and try to determine what caused the leak. The timing of the next launch attempt will be dependent on how long it takes to execute a recovery plan.

Engineers also will be sorting out a couple of other problems with gaseous nitrogen and gaseous helium systems. Range safety officers also will need to resolve trouble with one of two instruments required to make certain command destruct signals are properly encoded. The destruct signals would be beamed up to the rocket if it careened out of control and threatened populated areas.

kl90

Report: Gration off list to head NASA
The New York Times reports that President Barack Obama will tap Maj. Gen. Jonathan Scott Gration to be his special envoy to Sudan.

That would take Gration, one of the president's top military and foreign policy advisers, out of the running to be NASA chief. FLORIDA TODAY has a call into the White House to confirm the appointment.

Gration had been floated as a possible NASA head, although that was met with a cool reception from U.S. Sen. Bill Nelson, who sits on the committee that will hold confirmation hearings for the nominee. Nelson urged Obama to select a candidate with a space background.

A handful of candidates remain on the shortlist to repace former NASA chief Michael Griffin, including Steve Isakowitz, a former NASA official now with the Energy Department. Former NASA astronaut Charles Bolden Jr., and retired Air Force general Lester Lyles also appear to be on the shortlist.

kl90

Altas V launch off for this week
The launch of an Atlas V rocket carrying a new-generation military communications satellite won't take place this week.

Last night's planned launch was scrubbed to give engineers time to investigate the failure of an upper-stage engine valve. At the time, officials said it was being delayed until at least Friday.

After a preliminary review, Air Force and United Launch Alliance mission managers determined that the launch can't take place before a previously scheduled Delta II launch slated for next Tuesday.

The Air Force noted that launch managers are also aware of the planned March 28 return of Space Shuttle Discovery.

Mission managers "will work with the 45th Space Wing to request an open launch date on the Eastern Range when the determination is made that the Atlas V is ready for a second launch attempt."

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Former Mel High Teacher Enjoyed Launch
Blasting off from Kennedy Space Center felt like riding a roller coaster "on steroids," but surprisingly smooth, Discovery astronaut and former Melbourne High science teacher Joe Acaba told students today.

"It's like a big roller coaster, maybe on steroids," he said during a session in which four astronauts on the International Space Station answered questions submitted by students across the country. "One thing that surprised me is it was a lot smoother than I thought it would be, but it's a feeling that I know I'll never forget."

Acaba taught ninth-graders in Melbourne in 1999-2000, his first year as a teacher. Then he moved on to Dunnellon Middle for personal reasons.

He and Ricky Arnold were two of three "educator astronauts" NASA picked in 2004. The agency hopes they help inspire young people to study math and science and pursue careers in engineering and aerospace.

Discovery's busy 13-day mission, which was shortened a day because of launch delays, doesn't allow time for the former educators to teach from space. But today's media event with Channel One was an effort to communicate with students.

Acaba showed off a sweet tooth in response to a question about food eaten on orbit. He caught a piece of floating chocolate offered by Arnold.

"We have all kinds of goodies," he said.

The 41-year-old father of two, NASA's first astronaut of Puerto Rican descent, is in his third day in space.

He grew up in California watching film reels of Apollo moon landings with his father and grandfather, and was an avid reader of science fiction.

Now he's awaiting his turn to walk in space. He's scheduled to participate in the mission's second and third spacewalks, planned Saturday and Monday.

Acaba invited several former colleagues from Melbourne and other Brevard County schools to watch Discovery's launch Sunday. And he packed a Melbourne High flag among the personal items he took into orbit.

The school hopes he'll return for a visit after the mission.

Acaba also responded to questions about how astronauts shower and go to the bathroom in space, and the most beautiful thing he's seen so far in space.

"I think for me what's been most impressive is when you're looking out a window, and it's very dark outside, and all of the sudden the sun starts to come up, and you start to see a little bit of blue, you see the atmosphere," he said. "And it's just an incredible view and one you can't really get on Earth. So that's been great to see that happen about every 45 minutes here."

The crew is having a mid-day meal before resuming work to move the Starboard 6 truss into position for installation on Thursday.

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Senators urge Obama to remove NASA watchdog
FLORIDA TODAY's Eun Kyung Kim reports:

WASHINGTON - A group of U.S. senators is urging President Barack Obama to immediately remove NASA Inspector General Robert "Moose" Cobb from his job, calling him an ineffective and vindictive leader.

"Since his appointment in 2002, Mr. Cobb has been repeatedly accused of stifling investigations, retaliating against whistleblowers and prioritizing social relationships with top NASA officials over proper federal oversight," the lawmakers said in their letter Wednesday to the president.

Sen. Jay Rockefeller, the West Virginia Democrat who chairs the Senate Commerce, Science and Transportation Committee, which oversees NASA, wrote the letter with Sens. Claire McCaskill, D-Mo., and Charles Grassley, R-Iowa.

The lawmakers are among the latest to demand Cobb leave his position. Last year, a similar call was made by Sen. Bill Nelson, a Florida Democrat who sits on the commerce panel, and Rep. Bart Gordon, the Tennessee Democrat who chairs the House Science and Technology Committee.

Former President George W. Bush nominated Cobb and continued to back him even after an independent presidential panel report said Cobb created a hostile work environment and "compromised numerous investigations due to ties to agency leadership."

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Gration off shortlist to be NASA chief
Here is more on retired Air Force Gen. Scott Gration coming off the shortlist to be the next NASA administrator.

From FLORIDA TODAY's Eun Kyung Kim in Washington:

WASHINGTON - Scratch Scott Gration off the shortlist to be the next NASA administrator.

President Barack Obama announced Wednesday that he plans to appoint the retired Air Force general as his special envoy to Sudan.

The role may be a better fit than the NASA gig for Gration, an Obama loyalist who grew up in Africa as the son of missionaries.

"I have worked closely and directly with Gen. Gration for several years, and have traveled with him to refugee camps in Chad filled with those who were displaced by the genocide in Darfur," Obama said in a statement. "He is a valued personal friend and I am pleased he has accepted this assignment. He knows the region, has broad experience, and has my complete confidence."

Earlier this year, Gration was floated as a contender for NASA chief, but that idea received a cool reception from U.S. Sen. Bill Nelson and other critics who argued Gration lacked space experience.

A handful of candidates still remain as possible administrator contenders, including Steve Isakowitz, a former NASA official now with the Energy Department, former astronaut Charles Bolden Jr. and retired Air Force general Lester Lyles.