Spaceflight Now





Discovery astronauts set for one more spacewalk today
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: September 5, 2009


Bookmark and Share

Astronauts John "Danny" Olivas and Christer Fuglesang are gearing up for a third and final spacewalk today, a planned six-and-a-half-hour excursion to deploy a payload mounting mechanism, replace a circuit breaker and an orientation sensor, install GPS antennas and to lay 60 feet of cable to power a new module.


Credit: NASA
 
The spacewalk is scheduled to begin at 4:49 p.m. EDT, although the astronauts could get out early if preparations go smoothly. For identification, Olivas, call sign EV-1, will be wearing a spacesuit with red stripes around the legs. Fuglesang, EV-2, will be wearing an unmarked suit.

This will be the 133rd spacewalk devoted to station assembly and maintenance since construction began in 1998 and the 14th so far this year. Going into today's excursion, station assembly EVA time stood at 823 hours and 50 minutes, including 13 hours and 14 minutes for Discovery's crew.

Today's spacewalk was replanned following an EVA Thursday in which Olivas ran into problems routing a power cable on a docking port where a new module is scheduled to be attached next year. A bundle of four cables was not in the expected position on the port and that task was dropped from the Discovery crew's timeline pending additional analysis. Longer jumper cables likely will be needed to hook up the cables in question.

"On EVA-2, when we got to the get aheads and discovered the cables weren't in exactly the right config we intended them to be in, we called the crew off and thought about it for the rest of the day," said space station Flight Director Royce Renfrew. "We went ahead and pulled that off the EVA-3 timeline and added some other get-ahead tasks. It's actually a fairly full timeline."

The first item on the agenda is to deploy a payload attachment mechanism on the upper right side of the station's solar power truss. The mechanism will be needed in November when the crew of the next shuttle visiting the station delivers two external logistics carriers, or ELCs, carrying critical spare parts and components.

ELC-1, which will be mounted on the left-side port-3 truss segment, will carry a solar array battery charge/discharge unit, a plasma contactor unit, a robot arm latching end effector, a control moment gyroscope, a nitrogen tank assembly, an ammonia tank assembly and a cooling system pump module.

ELC-2, which will be mounted on the starboard-3 truss attach mechanism being deployed today, will carry a high pressure gas tank, another control moment gyroscope, a pump module, a robot arm transporter umbilical system, experiment support equipment and flight attachment mechanisms.

"We're also going to go play with the rate gyro assembly," Renfrew said. "When we go around the Earth, we not only need to know where we are and how fast we're going, but one of the things we need to know to be able to do attitude determination and to essentially point the vehicle in the right direction is know how fast we're actually moving in any axis.

"So if we're pitching or yawing or rolling, if we're changing the attitude of the stack in any of those three (axes), we need to know how fast we're actually changing there. So we have some pretty high-tech equipment on the vehicle, the rate gyro assemblies. One of those has failed. On this EVA we'll go replace that rate gyro. We're also going to replace two GPS antennas, Global Positioning System antennas."

While Olivas replaces the first of two GPS antennas, Fuglesang will remove a failed remote power control module, or RPCM, in the power truss electrical system. The work requires a partial shut down of critical systems, including a stabilizing gyroscope and one of the station's two external cooling loops.

"When we go to change that out, we have to get the safing in place before the EV crew members can safely handle that RPCM," Renfrew said. "In order to get the safing in place, we have to go upstream to a different power module and power it off there. Somewhat similar to if you're in your house and you wanted to go change out a plug in the wall, you'd probably go outside and turn the circuit breaker off to make sure that's not live. Same thing here, only when we go upstream of that RPCM it turns off a lot of equipment on the truss.

"That's pretty complicated and requires a lot of choreography between the EV crew and the ground to make all that work flawlessly."

Finally, Olivas and Fuglesang will work together to run 60-foot-long cables from a distribution box in the solar power truss down to the left side of the Unity connecting module where a new module, known as node 3, or Tranquility, is scheduled for attachment early next year.

"These cables are about an inch and a half of two inches in diameter and they're really stiff," said Zeb Scoville, the lead spacewalk officer for Discovery's mission. "We've coiled up loops of this cable into maybe a diameter of about two feet. With each coil, we've taken one of these copper wire ties ... and we twist each loop with one of these wire ties.

"As they pull off one loop, they can release that one wire tie, pull off maybe just five or so feet, secure that down to structure while they hold onto the rest of it, they can move down the truss structure a little bit, undo one twist tie, get the second loop off and start working on that. As controlled as that may sound, cables have always presented a challenge in the past just because they do have a lot of memory and sort of a mind of their own. We've done our best to try to control that."

While the spacewalk is going on, returning station astronaut Timothy Kopra and station flight engineer Robert Thirsk will spend three hours or so replacing one of 16 motor-driven bolts holding the Leonardo cargo module to the Harmony module's Earth-facing port. Engineers noticed higher-than-normal drive currents in the bolt earlier and during a test this week, it jammed.

"Unfortunately, Murphy's Law holds true because the one bolt that we're after is buried under a bunch of other structure," Renfrew said. "We'll take that out, put it back together. ... It'll be about a three-hour task. That'll all be taken care of before we need to get the MPLM (Leonardo cargo module) off the vehicle."

Finally, station flight engineers Michael Barratt and Frank De Winne will spend their afternoon replacing a presumably clogged filter in the U.S. oxygen generation assembly.

Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision I of the NASA television schedule):


EDT........DD...HH...MM...EVENT

09/05
11:59 AM...07...12...00...STS/ISS crew wakeup
12:34 PM...07...12...35...EVA-3: 14.7 psi repress/hygiene break
01:24 PM...07...13...25...EVA-3: Airlock depress to 10.2 psi
01:29 PM...07...13...30...ISS daily planning conference
01:44 PM...07...13...45...ISS: Harmony nadir CBM bolt replacement
01:44 PM...07...13...45...EVA-3: Campout EVA preps
03:14 PM...07...15...15...EVA-3: Spacesuit purge
03:29 PM...07...15...30...EVA-3: Spacesuit prebreathe
04:14 PM...07...16...15...MPLM transfers resume
04:19 PM...07...16...20...EVA-3: Crew lock depressurization
04:49 PM...07...16...50...EVA-3: Spacesuits to battery power
04:54 PM...07...16...55...EVA-3: Airlock egress
05:09 PM...07...17...10...EVA-3: Setup
05:24 PM...07...17...25...EVA-3: S3 upper payload attach deploy
06:54 PM...07...18...55...EVA-3: Rate gyro assembly 2 R&R
07:54 PM...07...19...55...EVA-3/EV-1: GPS-4 antenna install
07:54 PM...07...19...55...EVA-3/EV-2: S0 RPCM R&R
08:39 PM...07...20...40...EVA-3/EV-1: Node 3 cable routing
08:39 PM...07...20...40...EVA-3/EV-2: GPS-2 antenna install
08:59 PM...07...21...00...ISS: OGS filter replacement
08:59 PM...07...21...00...EVA-3/EV-2: Node 3 cable routing
10:24 PM...07...22...25...EVA-3/EV-1: Node 1 slide wire removal
10:44 PM...07...22...45...EVA-3: Cleanup and ingress
10:44 PM...07...22...45...ISS: "Buzz" EVA video
11:19 PM...07...23...20...EVA-3: Airlock repressurization
11:34 PM...07...23...35...Spacesuit servicing

09/06
12:24 AM...08...25...00...Evening planning conference
01:00 AM...08...01...01...Mission status briefing
02:59 AM...08...03...00...ISS crew sleep begins
03:29 AM...08...03...30...STS crew sleep begins
04:00 AM...08...04...01...Daily highlights reel
09:00 AM...08...09...01...Flight director's update
11:29 AM...08...11...30...Crew wakup

Spaceflight Now Plus
Additional coverage for subscribers:
VIDEO: FRIDAY AFTERNOON'S MISSION STATUS BRIEFING PLAY
VIDEO: FRIDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: FLIGHT DAY 7 HIGHLIGHTS MOVIE PLAY

VIDEO: POST-EVA MISSION STATUS BRIEFING PLAY
VIDEO: OLD TANK MOVED TO SHUTTLE FOR RECYCLING PLAY
VIDEO: NEW TANK HOOKED UP TO STATION UMBILICALS PLAY
VIDEO: CHRISTER FUGLESANG CARRIES NEW AMMONIA TANK PLAY
VIDEO: PREPS IN SHUTTLE BAY TO UNPACK NEW AMMONIA TANK PLAY
VIDEO: DANNY OLIVAS FLOATS OUT OF AIRLOCK TO START EVA PLAY
VIDEO: THURSDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: STEP-BY-STEP SUMMARY OF SPACEWALK NO. 2 PLAY

HIGH DEFINITION TV DAY 6: PREPPING FOR NEXT EVA PLAY
HIGH DEFINITION TV DAY 6: MOVING FROZEN SCIENCE PLAY
HIGH DEFINITION TV DAY 6: EMPTYING OUT LEONARDO PLAY

HIGH DEFINITION TV DAY 5: SPACEWALKERS CELEBRATE PLAY
HIGH DEFINITION TV DAY 5: OLIVAS AND STOTT ON EVA NO. 1 PLAY
HIGH DEFINITION TV DAY 5: COLBERT TREADMILL UNPACKED PLAY
HIGH DEFINITION TV DAY 5: SPACEWALKERS GET SUITED UP PLAY

HIGH DEFINITION TV DAY 4: LEONARDO MODULE OPENED PLAY
HIGH DEFINITION TV DAY 4: MOVING ITEMS FROM SHUTTLE PLAY

VIDEO: FLIGHT DAY 6 HIGHLIGHTS MOVIE PLAY
VIDEO: ASTRONAUTS' HOME MOVIES: DAY 6 PLAY
VIDEO: WEDNESDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: WEDNESDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY

VIDEO: FLIGHT DAY 5 HIGHLIGHTS MOVIE PLAY
VIDEO: POST-EVA MISSION STATUS BRIEFING PLAY
VIDEO: SPACEWALKERS PUT THIRD EXPERIMENT IN SHUTTLE PLAY
VIDEO: BRIEFCASE-LIKE PACKAGE RETRIEVED FROM STATION PLAY
VIDEO: EUROPEAN PAYLOAD MOVED FROM STATION TO SHUTTLE PLAY
VIDEO: SPACEWALKERS FREE COOLANT TANK FROM TRUSS PLAY
VIDEO: DANNY OLIVAS DISCONNECTS OLD AMMONIA TANK PLAY
VIDEO: ASTRONAUTS EMERGE FROM AIRLOCK TO START EVA PLAY
VIDEO: OVERVIEW OF FLIGHT DAY 5 ACTIVITIES PLAY
VIDEO: STEP-BY-STEP SUMMARY OF SPACEWALK NO. 1 PLAY
VIDEO: TUESDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY

VIDEO: FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: MONDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: NARRATED OVERVIEW OF THE LEONARDO PAYLOAD PLAY
VIDEO: ASTRONAUTS OPEN UP AND ENTER LEONARDO MODULE PLAY
VIDEO: TIME-LAPSE OF LEONARDO MODULE'S INSTALLATION PLAY
VIDEO: LEONARDO CARGO MODULE ATTACHED TO STATION PLAY
VIDEO: MONDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY
VIDEO: MONDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY

HIGH DEFINITION TV DAY 3: NICOLE STOTT ABOARD STATION PLAY
HIGH DEFINITION TV DAY 3: UNITING STATION AND SHUTTLE PLAY
HIGH DEFINITION TV DAY 3: JOIN THE CREW DURING DOCKING PLAY
HIGH DEFINITION TV DAY 3: LIFE ON RENDEZVOUS DAY PLAY

VIDEO: FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: SUNDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: SHUTTLE CREW WELCOMED ABOARD STATION PLAY
VIDEO: DOCKING RING RETRACTED TO JOIN TWO CRAFT PLAY
VIDEO: TIME-LAPSE OF DOCKING FROM CENTERLINE PLAY
VIDEO: SHUTTLE FLIES OUT IN FRONT OF STATION PLAY
VIDEO: DISCOVERY PERFORMS 360-DEGREE BACKFLIP PLAY
VIDEO: BEAUTIFUL VIEWS OF DISCOVERY APPROACHING PLAY
VIDEO: TIME-LAPSE VIEW FROM SHUTTLE DOCKING PORT PLAY
VIDEO: STATION CAMERA CATCHES DISCOVERY'S "TI BURN" PLAY
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
SUBSCRIBE NOW