The shuttle Discovery's Ku-band antenna system, used as a radar dish during rendezvous operations and to transmit video and data to and from the ground through NASA communications satellites, suffered a malfunction of some sort after the shuttle reached orbit Monday. Engineers are troubleshooting, but the system may be out of action for the duration of Discovery's mission.

Credit: NASA TV

"As far as the safety of the mission is concerned, we still have a lot of assets available at the International Space Station, so the safety of the mission in terms of making sure the heat shield on board Discovery and the overall health of the vehicle is fine," said Flight Director Mike Sarafin.

The shuttle's Ku-band communications system uses a dish antenna deployed from the forward right corner of the cargo bay to track NASA communications satellites, allowing the crew to downlink data and video and ground controllers to uplink commands and instructions when the shuttle is not within range of a U.S. ground station.

The system has two electronics boxes that control its ability to track target satellites, relay data and act as a radar during rendezvous operations. During the crew's initial attempts to activate the Ku-band antenna after reaching orbit Monday, the system failed a self test. Engineers attempted to power cycle the hardware, but the troubleshooting efforts were not immediately successful.

"We've seen pieces of this failure mode in the past, but we haven't seen this exact failure mode and we're still evaluating ... to understand really what's going on," Sarafin said. "But we've got rules and procedures and workarounds in place, not only to handle a no-radar rendezvous case but also to work around the loss of the imagery and other data that we would normally get down early in the mission. We'll get that down a little bit later using the station assets."

In the near term, Sarafin said, the Discovery astronauts will record imagery and laser scan data from a heat shield inspection planned for Tuesday and then downlink the data to the ground after the shuttle docks with the space station Wednesday. As for the docking itself, the crew is trained to use other instruments to execute the shuttle's final approach and the loss of Ku radar capability is not expected to cause any major problems.

But it will affect the crew's timeline.

"Right now, we don't have any major timeline modifications in the short term or major mission objectives that are in jeopardy," Sarafin said. "We're still going to press tomorrow with the flight day two inspection of the reinforced carbon carbon on the port and starboard (wing leading edge panels) and nose cap areas on Discovery. The crew's going to record all that information and then we'll transmit that over to station and downlink it from the station's Ku-band assets after we get docked.

"Other information that goes up, like the timeline modifications we have every morning as part of the mission, those are going to have to be verbalized up to the crew. It'll take a little bit longer in the morning to get the plan rolling as we've modified it overnight. ... As far as installing the Multi Purpose Logistics Module and all the EVAs we've got ahead of us, we're not tracking any changes to that plan and the team is off evaluating if there are any mission objectives we need to talk about any further."

The shuttle astronauts normally would rely on the Ku-band antenna to downlink data from a post-undocking "late" inspection of the nose cap and wing leading edge panels. If the Ku issue is not resolved by then, Sarafin said mission managers could opt to have the astronauts carry out the second inspection while still docked to the space station.

"The team is very good at developing timelines that make the best use of the 13-day plan that we've got ahead of us and we just need to let them work through that," he said. "Should we need to do the late inspection for orbital debris risk mitigation late in the docked mission, we certainly have the capability to do that. The station team has already been made aware that's a possible outcome and they're working with the various users of the Ku equipment aboard the station to reserve a downlink channel should we not be able to recover the shuttle's Ku antenna."

Additional coverage for subscribers:
VIDEO: DESCRIPTION OF KU-BAND ANTENNA PROBLEM PLAY

VIDEO: PREVIEW OF FLIGHT DAY 2 ACTIVITIES PLAY
VIDEO: NARRATED TOUR OF DISCOVERY'S PAYLOAD BAY PLAY

VIDEO: FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: SHUTTLE DISCOVERY BLASTS OFF! PLAY | HI-DEF
VIDEO: GO INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: POST-LAUNCH NEWS CONFERENCE PLAY

VIDEO: LAUNCH REPLAY: VAB ROOF PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PATRICK AFB PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD CAMERA 070 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD CAMERA 071 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PLAYALINDA BEACH PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD FRONT CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: KSC WEST TOWER PLAY | HI-DEF

VIDEO: ASTRONAUTS LEAVE CREW QUARTERS PLAY | HI-DEF
VIDEO: CREW FINISHES GETTING SUITED UP PLAY | HI-DEF

VIDEO: NARRATED REVIEW OF SHUTTLE'S PREPARATIONS PLAY | HI-DEF
VIDEO: NARRATED REVIEW OF PAYLOADS' PREPARATIONS PLAY | HI-DEF
VIDEO: PREPARING AN EXTERNAL TANK FOR LAUNCH PLAY | HI-DEF

VIDEO: TIME-LAPSE OF GANTRY ROLLING BACK FOR LAUNCH PLAY
VIDEO: LAUNCH PAD'S SERVICE TOWER RETRACTED PLAY | HI-DEF
VIDEO: PAYLOAD BAY DOORS CLOSED FOR LAUNCH PLAY | HI-DEF
VIDEO: ASTRONAUTS INSPECT THE PAYLOAD BAY PLAY | HI-DEF

VIDEO: STS-131 MISSION PREVIEW MOVIE PLAY | HI-DEF
VIDEO: PRE-LAUNCH INTERVIEW WITH COMMANDER POINDEXTER PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH PILOT JIM DUTTON PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH RICK MASTRACCHIOPLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH METCALF-LINDENBURGER PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH STEPHANIE WILSON PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH NAOKO YAMAZAKI PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH CLAY ANDERSON PLAY

VIDEO: PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: COUNTDOWN STATUS AND WEATHER OUTLOOK PLAY
VIDEO: PREVIEW OF DISCOVERY'S LAUNCH COUNTDOWN PLAY
VIDEO: ASTRONAUTS ARRIVE FOR LAUNCH PLAY | HI-DEF

VIDEO: FULL FLIGHT READINESS REVIEW NEWS BRIEFING PLAY
VIDEO: RECAP OF THE FLIGHT READINESS REVIEW PLAY | HI-DEF
VIDEO: HELIUM VALVE NO CONSTRAINT TO LAUNCH PLAY | HI-DEF
VIDEO: MANAGERS ASSESS ISSUES BEFORE FLIGHT PLAY | HI-DEF
VIDEO: UPDATE ON PRE-LAUNCH PREPS AT PAD 39A PLAY | HI-DEF

VIDEO: SPACEWALKING SUITS LOADED ABOARD PLAY | HI-DEF
VIDEO: INTERVIEW WITH STS-131 PAYLOAD MANAGER PLAY | HI-DEF
VIDEO: INTERVIEW WITH BOEING PAYLOAD MANAGER PLAY | HI-DEF
VIDEO: PAYLOADS DELIVERED TO LAUNCH PAD 39A PLAY | HI-DEF
VIDEO: TRANSPORT CANISTER ROTATED VERTICALLY PLAY | HI-DEF
VIDEO: LEONARDO PLACED INTO THE TRANSPORTER PLAY | HI-DEF
VIDEO: STATION'S NEW AMMONIA COOLANT TANK PLAY | HI-DEF
VIDEO: LEONARDO HATCH CLOSED FOR FLIGHT PLAY | HI-DEF
VIDEO: FILLING UP ONE OF THE SUPPLY RACKS PLAY | HI-DEF

VIDEO: CAN THE SHUTTLE PROGRAM AVOID LOOMING RETIREMENT? PLAY
VIDEO: WHAT ABOUT ADDING ONE MORE SHUTTLE MISSION? PLAY
VIDEO: FULL BRIEFING BY SHUTTLE AND STATION OFFICIALS PLAY
VIDEO: THE STS-131 MISSION OVERVIEW PRESENTATIONS PLAY
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY

VIDEO: SHUTTLE EVACUATION PRACTICE PLAY | HI-DEF
VIDEO: CREW MODULE HATCH IS CLOSED PLAY | HI-DEF
VIDEO: ASTRONAUTS BOARD DISCOVERY PLAY | HI-DEF
VIDEO: CREW BRIEFED ON EMERGENCY PROCEDURES PLAY | HI-DEF
VIDEO: TEST-DRIVING AN EMERGENCY ARMORED TANK PLAY | HI-DEF
VIDEO: NIGHTTIME APPROACHES IN TRAINING AIRCRAFT PLAY | HI-DEF
VIDEO: ASTRONAUTS CHAT WITH REPORTERS AT PAD 39A PLAY
VIDEO: CREW ARRIVES FOR PRACTICE COUNTDOWN PLAY | HI-DEF

VIDEO: GANTRY PLACED AROUND DISCOVERY PLAY | HI-DEF
VIDEO: DISCOVERY REACHES PAD 39A PLAY | HI-DEF
VIDEO: OVERNIGHT ROLLOUT BEGINS PLAY | HI-DEF
VIDEO: SHUTTLE HOISTED FOR ATTACHMENT TO TANK PLAY | HI-DEF
VIDEO: CRANE ROTATES THE ORBITER VERTICALLY PLAY | HI-DEF
VIDEO: DISCOVERY MOVES TO ASSEMBLY BUILDING PLAY | HI-DEF

VIDEO: ASTRONAUTS VISIT THEIR SPACECRAFT PLAY | HI-DEF
VIDEO: CREW GOES INSIDE LEONARDO MODULE PLAY | HI-DEF

VIDEO: EXTERNAL TANK ATTACHED TO BOOSTERS PLAY | HI-DEF
VIDEO: FUEL TANK LIFTED INTO CHECKOUT CELL PLAY | HI-DEF
VIDEO: EXTERNAL TANK ARRIVES AT SPACEPORT PLAY | HI-DEF

VIDEO: DISCOVERY'S NOSE POD ATTACHED PLAY | HI-DEF
VIDEO: INSTALLING DISCOVERY'S MAIN ENGINES PLAY | HI-DEF
VIDEO: KSC'S SHUTTLE MAIN ENGINE SHOP PLAY | HI-DEF
VIDEO: GASEOUS NITROGEN TANK REMOVED PLAY | HI-DEF
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