The shuttle Discovery's external tank appears to have performed well during the ship's launch overnight Friday. While engineers will not complete a detailed analysis for several more days, no major problems or foam loss have been seen so far in NASA's initial looks at ascent imagery and other data.

Credit: NASA

"The launch and the ascent was just beautiful and the performance of the vehicle was exceedingly good," LeRoy Cain, chairman of NASA's Mission Management Team, told reporters Sunday. "We're safely on orbit, the crew is preparing for rendezvous and docking later this afternoon and evening and we're looking forward to that."

Shuttle commander Frederick "C.J." Sturckow will be flying the final approach to the station Sunday evening using the shuttle's big primary reaction control system thrusters, or PRCS jets, instead of less-powerful vernier jets. Two 24-pound-thrust vernier rocket engines are available in a nose-mounted rocket pod while four are available in the aft.

But the right-firing forward vernier jet failed shortly after launch, forcing flight controllers to close a manifold and isolate both forward thrusters. As a result, Sturckow will be making NASA's first space station rendezvous and docking carried out with the larger 870-pound-thrust primary maneuvering rockets.

"At this point, vernier thrusters are not available to us," Cain said. "We do have a couple of backup modes to the verniers and so it's really not a problem for us to use the other thrusters for attitude control and for maneuvers. ... The crew is very well trained for this particular failure mode, they've trained it numerous times. And so we don't have any concerns for that."

Using what's known as the ALT-DAP, or alternate digital autopilot mode, the shuttle's flight computers will fire the primary jets as required to maintain Discovery's orientation in space while Sturckow, flying the shuttle from the aft flight deck, will use the big thrusters to move in for docking around 9:04 p.m. EDT.

"I would characterize it as being slightly more challenging, simply because of the different autopilot modes the crew trains to and flies with," Cain sad. "They've certainly done more training where we have vernier autopilot mode available to us than cases where they don't have it."

Once docked, the orientation of the combined shuttle-station "stack" will be maintained primarily by the station's control moment gyroscopes and Russian rocket thrusters. The shuttle's vernier jets normally are used to supplement the gyros, but that option is not available this time around.

"It's a pretty sophisticated DAP mode where based on moments of inertia, the DAP can figure out which jets to fire individually to maintain attitude control and to do maneuvers," Cain said. "We have both of those modes for shuttle flying alone. Once we're docked, we do have the ability to use ALT-DAP for attitude hold (but) it's lower priority than some of the other modes for handling attitude for shuttle station combined."

During the shuttle Endeavour's launching in July, an unusual amount of foam insulation fell away from the central intertank region of the ship's external tank. In addition, a piece of foam separated from an ice-frost ramp on the upper liquid oxygen section, the second flight in a row to experience that problem.

Discovery's flight was delayed while engineers conducted extensive tests to make sure the next two tanks in the launch sequence were in good shape. Cain said based on a very preliminary look at the data, the intertank foam and the ice-frost ramps on Discovery's tank suffered no major losses.

"From what I've been told, what we have seen is what we consider to be normal kind of erosion on a couple of the ice-frost ramps on the LOX tank," Cain said. "Don't see any losses, if you will, on the ice-frost ramps, nothing like on (the last two missions) where we had losses on the 718 IFR. So that looked really good to us."

Likewise, "the intertank looked very good. As you know, we had several areas of losses from the interank on the previous mission and the intertank (on Discovery's tank) looked very good. We had one loss that I believe was in the intertank flange area, so the folks will be looking at that. ... But that would be very much in family with what we've been seeing on all these missions."

Additional coverage for subscribers:
VIDEO: SUNDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY
VIDEO: NARRATED PREVIEW OF RENDEZVOUS AND DOCKING PLAY
VIDEO: THE MOON SINKS BELOW TAIL OF DISCOVERY PLAY
VIDEO: ASTRONAUTS' HOME MOVIES: DAY 2 PLAY
VIDEO: ASTRONAUTS' HOME MOVIES: DAY 1 PLAY

VIDEO: FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: SATURDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: NARRATED PREVIEW OF SHUTTLE INSPECTIONS PLAY

VIDEO: LAUNCH REPLAY: INSIDE MISSION CONTROL ROOM PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD CAEMRA 070 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD CAEMRA 071 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: UCS-23 TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PLAYALINDA BEACH PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD FRONT CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PATRICK AIR FORCE BASE PLAY | HI-DEF

VIDEO: POST-LAUNCH BRIEFING PLAY
VIDEO: FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: THE FULL LAUNCH EXPERIENCE PLAY
VIDEO: LIFTOFF OF SPACE SHUTTLE DISCOVERY! PLAY | HI-DEF
VIDEO: COMMANDER RICK STURCKOW BOARDS DISCOVERY PLAY
VIDEO: PILOT KEVIN FORD BOARDS SHUTTLE DISCOVERY PLAY
VIDEO: MISSION SPECIALIST PAT FORRESTER BOARDS DISCOVERY PLAY
VIDEO: MISSION SPECIALIST JOSE HERNANDEZ BOARDS SHUTTLE PLAY
VIDEO: MISSION SPECIALIST DANNY OLIVAS BOARDS DISCOVERY PLAY
VIDEO: MISSION SPECIALIST CHRISTER FUGLESANG BOARDS PLAY
VIDEO: MISSION SPECIALIST NICOLE STOTT BOARDS DISCOVERY PLAY
VIDEO: ASTRONAUTS LEAVE CREW QUARTERS BUILDING PLAY | HI-DEF
VIDEO: CREW FINISHES GETTING SUITED UP PLAY | HI-DEF

VIDEO: NARRATED MISSION OVERVIEW MOVIE PLAY | HI-DEF
VIDEO: MEET SHUTTLE DISCOVERY'S ASTRONAUTS PLAY | HI-DEF
VIDEO: NARRATED REVIEW OF SHUTTLE'S PREPARATIONS PLAY | HI-DEF
VIDEO: NARRATED REVIEW OF PAYLOADS' PREPARATIONS PLAY | HI-DEF
VIDEO: THE "COLBERT" TREADMILL PLAY | HI-DEF

VIDEO: MANAGERS EXPLAIN REASON FOR SECOND SCRUB PLAY
VIDEO: WEATHER SCRUBS FIRST COUNTDOWN PLAY | HI-DEF
VIDEO: ASTRONAUTS DEPART QUARTERS FOR PAD 39A PLAY | HI-DEF
VIDEO: CREW GETS SUITED UP FOR LAUNCH ATTEMPT PLAY | HI-DEF
VIDEO: LAUNCH PAD SERVICE GANTRY ROLLED BACK PLAY | HI-DEF

VIDEO: PRE-LAUNCH INTERVIEW WITH RICK STURCKOW PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH KEVIN FORD PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH PAT FORRESTER PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH JOSE HERNANDEZ PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH DANNY OLIVAS PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH CHRISTER FUGLESANG PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH NICOLE STOTT PLAY

VIDEO: AMERICAN AND EUROPEAN PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: THE LAUNCH COUNTDOWN GETS UNDERWAY PLAY
VIDEO: ASTRONAUTS ARRIVE AT THE CAPE FOR LAUNCH PLAY | HI-DEF
VIDEO: FLIGHT READINESS REVIEW SETS LAUNCH DATE PLAY

VIDEO: SHUTTLE AND STATION PROGRAM UPDATE PLAY
VIDEO: THE STS-128 MISSION OVERVIEW BRIEFING PLAY
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY
VIDEO: SHUTTLE PROGRAM MANAGER EXPLAINS FOAM ISSUES PLAY

VIDEO: PAYLOAD BAY DOORS CLOSED FOR FLIGHT PLAY | HI-DEF
VIDEO: MISSION CARGO LOADED ABOARD DISCOVERY PLAY | HI-DEF

VIDEO: CREW TOURS PAD'S CLEANROOM PLAY | HI-DEF
VIDEO: SHUTTLE EVACUATION PRACTICE PLAY | HI-DEF
VIDEO: ASTRONAUTS BOARD DISCOVERY PLAY | HI-DEF
VIDEO: THE LAUNCH DAY SIMULATION BEGINS PLAY | HI-DEF
VIDEO: PAD BUNKER TRAINING FOR THE CREW PLAY | HI-DEF
VIDEO: CREW BRIEFED ON EMERGENCY PROCEDURES PLAY | HI-DEF
VIDEO: NIGHTTIME APPROACHES IN TRAINING AIRCRAFT PLAY | HI-DEF
VIDEO: TEST-DRIVING EMERGENCY ARMORED TANK PLAY | HI-DEF
VIDEO: INFORMAL CREW NEWS CONFERENCE AT LAUNCH PAD PLAY
VIDEO: ASTRONAUTS ARRIVE FOR PRACTICE COUNTDOWN PLAY

VIDEO: SHUTTLE DISCOVERY ROLLS OUT PAD 39A PLAY | HI-DEF
VIDEO: ORBITER HOISTED FOR MATING TO TANK PLAY | HI-DEF
VIDEO: DISCOVERY MOVED TO ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: TIME-LAPSE OF DISCOVERY ARRIVING IN VAB PLAY

VIDEO: PAYLOADS DELIVERED TO LAUNCH PAD PLAY | HI-DEF
VIDEO: LEONARDO PUT INTO TRANSPORTER PLAY | HI-DEF
VIDEO: STATION'S NEW AMMONIA TANK PLAY | HI-DEF
VIDEO: MPLM HATCH CLOSED FOR FLIGHT PLAY | HI-DEF
VIDEO: INSIDE SHUTTLE MAIN ENGINE SHOP PLAY | HI-DEF
VIDEO: CREW EQUIPMENT INTERFACE TEST PLAY | HI-DEF
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