First spacewalk of Discovery's mission on tap today
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 3, 2008
Astronauts Michael Fossum and Ronald Garan are gearing up for a six-and-a-half-hour spacewalk today to retrieve a shuttle heat shield inspection boom mounted on the international space station; prepare the huge Japanese Kibo lab module for installation; and attempt to clean contamination from a critical solar array rotary joint.
"Obviously, it's going to be a really big day for Japan," said space station Flight Director Emily Nelson. "They've been working very hard on this module and all of the systems in it. It's a big day for us as well, bringing the largest laboratory that we'll have on the space station on orbit and getting it up and running, getting our Japanese partner up and running in a full 24-hour capacity, actively running science out of their module."
Discovery docked with the space station Monday after a flawless rendezvous. Opening a final hatch between the shuttle and the lab complex, Discovery commander Mark Kelly called out, "Hey, are you looking for a plumber?" Work to repair the station's balky Russian toilet is planned for Wednesday.
The Discovery astronauts were awakened today at 6:32 a.m. by a recording of "Hold Me With The Robot Arm" beamed up from mission control for Japanese astronaut Akihiko Hoshide. The song was performed by high school friends of Hoshide's and it was an appropriate selection given today's agenda: if all goes well, Hoshide and Karen Nyberg, operating the station's robot arm, will pull 15-ton Kibo from the shuttle's cargo bay around 4:37 p.m. and attach it to the left-side port of the Harmony module.
"Good morning, Discovery. And good morning, Aki," astronaut Shannon Lucid called from Houston.
"Good morning, Shannon, and the team," Hoshide replied. "Thanks for a great song. That was a song from my high school friends. We're looking forward to a great day, an exciting day to install Japanese Kibo module and a great day of EVA and robotics. Looking forward to working with you guys."
Fossum and Garan spent the night in the station's Quest airlock module at a reduced pressure of 10.2 pounds per square inch to help purge nitrogen from their bloodstreams and prevent the bends after a day spent working in NASA's 5-psi spacesuits.
Today's spacewalk, the first of three planned for Discovery's mission, is scheduled to begin at 11:32 a.m. This will be the 110th spacewalk devoted to station assembly and maintenance since construction began in 1998. Total station spacewalk time going into today's excursion was 686 hours and four minutes.
For identification, Fossum, call sign EV-1, will be wearing a suit with red stripes around the legs. Garan, call sign EV-2, will be wearing an unmarked suit.
Discovery was launched without a heat shield inspection boom normally used on the second day of a shuttle flight to look for signs of impact debris damage. The Kibo module, designed and built before the 2003 Columbia disaster, virtually fills the shuttle's cargo bay and there was no room for the 50-foot-long orbiter boom sensor system, or OBSS, robot arm extension.
As a result, the crew of the most recent shuttle assembly mission left their boom behind on the station in March. During today's spacewalk, after the station arm locks onto the boom, Garan will disconnect it from support fittings and keep-alive power. Nyberg and Hoshide, operating the station arm, will pull the boom away and position it for handoff to the shuttle's arm, operated by Nyberg and pilot Kenneth Ham. The boom will be used later in the mission to carry out a detailed inspection of Discovery's nose cap and wing leading edge panels, which experience the most extreme heating during re-entry.
While Garan works to disconnect the OBSS, Fossum will be busy removing restraints that held a robot arm camera in place before moving up to assist Garan. Both astronauts then will prepare Kibo for unberthing and installation, removing eight contamination covers protecting the module's common berthing system components and one of two window covers. At that point, Kibo will be ready for unberthing and installation on Harmony.
Unberthing is targeted for 4:37 p.m. with installation on the forward Harmony connecting module beginning around 6:07 p.m. If all goes well, the astronauts will open hatches and enter the new module Wednesday afternoon.
With Kibo preparations complete, Fossum and Garan will make their way to the starboard solar alpha rotary joint, or SARJ, on the right side of the station's main power truss.
The space station is equipped with two massive rotary joints on each side of the power truss. Ten-foot-wide motor-driven gears turn outboard solar arrays like paddle wheels to track the sun as the station circles the Earth, maximizing power production.
The left-side SARJ works normally in so-called "auto-track" mode, but the right-side unit has been used only sparingly since last fall because of extensive metallic contamination discovered during a spacewalk after engineers noticed high vibration levels and power usage.
Engineers now believe the contamination may have been caused by the breakdown of a super-hard outer layer. If cracks developed in that layer, the pressure exerted by the bearings the drive gears rolls through could cause additional damage, resulting in additional breakdown.
Whatever the cause, NASA would like to clean up the metal shavings if possible to permit engineers to rotate the outboard solar arrays as required to maximize power production.
Fossum will try a decidedly low-tech solution - applying Braycote grease to a small section of the race ring and then simply wiping the grease and trapped contaminants away. If it works, future shuttle crews may be asked to clean the entire race ring, permitting resumption of at least partial operation.
But because of the damage already done and the higher-than-normal vibration it causes, NASA managers believe astronauts eventually will be forced to move the starboard SARJ's 12 bearing assemblies to a backup outboard drive gear. But that is something they do not want to do unless absolutely necessary to avoid losing redundancy.
"We just recently squeezed in the SARJ cleaning task," Fossum said before launch. "It's really a test objective, to see what it would take to clan some of the metal that appears to be on the ring. We don't have a lot of information about it. So we're literally going out there with the kinds of tools you have in your garage.
"The first thing we're going to do is take a scraper to it and see if we can scrape some of that stuff off to make that surface a little more smooth for the rollers. Next, we're going to put down, literally, a little grease, it's a special space grease and then scrape on that and try to pick up material with it and wipe it off.
"And the third way is just putting down a little bit of this same grease and then taking a wipe, very much like a terry cloth towel, just to see if we can clean it up with this, knowing there's a very large ring out there and what we're trying to find is a technique that could be used to clean it up just a bit. But that's going to be a lot of work to go tackle the whole thing."
While Fossum works to clean a section of the race ring, Garan will re-install a SARJ bearing assembly that was removed earlier as part of ongoing troubleshooting.
Getting the starboard SARJ back in auto-track mode is critical for the long-term health of the space station. Only by tracking the sun as the station swings around the planet can the arrays generate the electrical power needed to operate all of the station's life support systems and experiment facilities.
"Even if we're able to rotate and be comfortable that the drive system can drive through any high current events that might occur, we still have the vibration that takes life out of the structure," said station Program Manager Mike Suffredini. "And so, that's one of the things we'll meter, how much we can rotate after we clean it up.
"So we've got a lot of forward work there to do. We've got to figure out how to clean this up even if we go to outboard ops, which I'm assuming is where we'll eventually end up, we need to clean a lot of this contamination off just so it doesn't liberate and find its way over (to the other drive gear) in the future."
Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision D of the NASA television schedule):
EDT........DD...HH...MM...EVENT 06/03/08 06:32 AM...02...13...30...Crew wakeup 07:00 AM...02...13...58...Flight director update (replay) 07:12 AM...02...14...10...EVA-1: 14.7 psi repress/hygiene break 07:57 AM...02...14...55...EVA-1: Airlock depress to 10.2 psi 08:02 AM...02...15...00...Station arm (SSRMS) maneuvers to OBSS grapple position 08:22 AM...02...15...20...EVA-1: Campout EVA preps 08:47 AM...02...15...45...ISS daily planning conference 09:57 AM...02...16...55...EVA-1: Spacesuit purge 10:12 AM...02...17...10...EVA-1: Spacesuit prebreathe 11:02 AM...02...18...00...EVA-1: Crew lock depressurization 11:32 AM...02...18...30...EVA-1: Spacesuits to battery power 11:37 AM...02...18...35...EVA-1: Airlock egress 12:07 PM...02...19...05...EVA-1 (Garan): OBSS boom transfer to shuttle 12:07 PM...02...19...05...EVA-1 (Fossum): Elbow camera release 12:27 PM...02...19...25...EVA-1 (Fossum): Open node 2 window covers 12:47 PM...02...19...45...EVA-1 (Fossum): MCAS 12:57 PM...02...19...55...EVA-1 (Fossum): OBSS boom transfer to shuttle 01:27 PM...02...20...25...EVA-1 (Fossum): JPM preps 01:42 PM...02...20...40...SRMS grapples OBSS boom 01:47 PM...02...20...45...SSRMS ungrapples OBSS boom 01:57 PM...02...20...55...EVA-1 (Garan): JPM preps 02:32 PM...02...21...30...SSRMS grapples Node 2 02:47 PM...02...21...45...SOKOL suit leak check 03:07 PM...02...22...05...SOKOL suit drying 03:17 PM...02...22...15...EVA-1 (Fossum): Release PM window launch locks 03:37 PM...02...22...35...EVA-1 (Fossum): S3/S4 SARJ datam A inspection 03:37 PM...02...22...35...EVA-1 (Garan): SARJ trundle bearing installation 04:17 PM...02...23...15...SSRMS grapples JPM 04:22 PM...02...23...20...EVA-1 (Fossum): SARJ cleaning test 04:37 PM...02...23...35...SSRMS unberths JPM 05:07 PM...03...00...05...EVA-1: Get aheads 05:32 PM...03...00...30...EVA-1: Cleanup and airlock ingress 06:02 PM...03...01...00...EVA-1: Airlock repressurization 06:07 PM...03...01...05...JPM installation 06:12 PM...03...01...10...Spacesuit servicing 06:27 PM...03...01...25...CBM first stage bolts 06:47 PM...03...01...45...CBM second stage bolts 07:22 PM...03...02...20...CBCS deactivation and removal 08:00 PM...03...02...58...Mission status briefing on NTV 08:17 PM...03...03...15...JPM vestibule pressure leak check 10:02 PM...03...05...00...ISS crew sleep begins 10:32 PM...03...05...30...STS crew sleep begins 11:00 PM...03...05...58...Daily video highlights reel on NTV