Spaceflight Now | STS-123 Shuttle Report | Dextre testing, module outfitting and tile repair tests

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Dextre testing, module outfitting and tile repair tests
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: March 10, 2008

The day after the second spacewalk, the astronauts and flight controllers will carry out tests to make sure Dextre's assembled appendages are working properly, participate in media interviews and prepare for spacewalk No. 3 the following day.


DATE/EDT.......DD...HH...MM...EVENT

03/16/08
Sun 03:28 PM...05...13...00...Crew wakeup
Sun 04:58 PM...05...14...30...JAXA PAO event
Sun 05:18 PM...05...14...50...ISS daily planning conference
Sun 05:43 PM...05...15...15...Brake run in arm 1
Sun 06:43 PM...05...16...15...Brake run in arm 2
Sun 07:48 PM...05...17...20...JLP outfitting
Sun 08:48 PM...05...18...20...Spacesuit swap
Sun 09:18 PM...05...18...50...Joint crew meal
Sun 10:18 PM...05...19...50...PAO event (all)
Sun 10:38 PM...05...20...10...JLP outfitting
Sun 10:58 PM...05...20...30...EVA-3: Tool config
Sun 11:48 PM...05...21...20...SPDM arm 1 SLP stow

03/17/08
Mon 12:58 AM...05...22...30...Airlock preps
Mon 03:28 AM...06...01...00...EVA-3: Procedures review
Mon 05:38 AM...06...03...10...EVA-3: Airlock depress to 10.2 psi
Mon 06:28 AM...06...04...00...STS crew sleep begins

Linnehan and Behnken will spend the night in the Quest airlock module to prepare for the mission's third spacewalk. With Linnehan once again on the end of the station's robot arm, the astronauts will wrap up the Dextre assembly work by removing a final set of thermal covers and installing the robot's tool carrier. Behnken also will install a camera pan and tilt unit and prepare the Spacelab pallet for its eventual reberthing in the shuttle for the return to Earth.

Linnehan, meanwhile, will move back to the shuttle's cargo bay, collect an experiment mounting platform and attach it to the outboard end of the European Columbus research module. He then will move a spare robot arm yaw joint and two spare electronic power units, called direct current switching units, or DCSUs, from the shuttle to an external storage platform on the station.

At that point, Linnehan will be done. As he is winding up his work, Behnken will retrieve a materials exposure experiment, known as MISSE-6, and attach it to the mounting fixture Linnehan earlier bolted to the Columbus module. After the astronauts return to the Quest airlock module, the station's robot arm will lock onto Dextre to prepare for its move the next day to a mounting point on the Destiny lab module.


DATE/EDT.......DD...HH...MM...EVENT

03/17/08
Mon 02:28 PM...06...12...00...Crew wakeup
Mon 03:08 PM...06...12...40...EVA-3: 14.7 psi repress/hygiene break
Mon 03:53 PM...06...13...25...EVA-3: Airlock depress to 10.2 psi
Mon 04:18 PM...06...13...50...EVA-3: Campout EVA preps
Mon 05:48 PM...06...15...20...EVA-3: Spacesuit purge
Mon 05:58 PM...06...15...30...SSRMS setup
Mon 06:03 PM...06...15...35...EVA-3: Spacesuit prebreathe
Mon 06:53 PM...06...16...25...EVA-3: Crew lock depressurization
Mon 07:23 PM...06...16...55...EVA-3: Spacesuits to battery power
Mon 07:28 PM...06...17...00...EVA-3: Airlock egress
Mon 07:48 PM...06...17...20...EVA-3: Setup
Mon 07:58 PM...06...17...30...EVA-3 (Behnken): Tool holder removal; pallet install
Mon 08:08 PM...06...17...40...EVA-3 (Linnehan): Pallet install
Mon 09:23 PM...06...18...55...EVA-3 (Behnken): Spacelab pallet cleanup
Mon 09:23 PM...06...18...55...EVA-3 (Linnehan): Arm 2 blanket removal
Mon 09:53 PM...06...19...25...EVA-3 (Linnehan): MISSE-6 mounting bracket transfer
Mon 10:38 PM...06...20...10...EVA-3 (Behnken): Camera pan/tilt unit install (2)
Mon 10:53 PM...06...20...25...EVA-3 (Linnehan): Yaw joint transfer to station
Mon 11:18 PM...06...20...50...EVA-3 (Behnken): MISSE experiment relocate/deploy
Mon 11:38 PM...06...21...10...EVA-3 (Linnehan): DCSU 1 transfer to station

03/18/08
Tue 12:23 AM...06...21...55...EVA-3 (Linnehan): DCSU 2 transfer to station
Tue 01:13 AM...06...22...45...EVA-3: Cleanup
Tue 01:28 AM...06...23...00...SSRMS Dextre grapple maneuver
Tue 01:28 AM...06...23...00...EVA-3: Airlock ingress
Tue 01:53 AM...06...23...25...EVA-3: Airlock repressurization
Tue 02:08 AM...06...23...40...SSRMS grapples Dextre
Tue 02:28 AM...07...00...00...Spacesuit servicing
Tue 03:28 AM...07...01...00...Dextre release
Tue 03:48 AM...07...01...20...Dextre overnight park
Tue 06:28 AM...07...04...00...STS crew sleep begins

The day after spacewalk No. 3, the astronauts will move Dextre to a mounting point on Destiny and move the Spacelab pallet back to the shuttle's cargo bay for return to Earth.


DATE/EDT.......DD...HH...MM...EVENT

03/18/08
Tue 02:28 PM...07...12...00...Crew wakeup
Tue 04:28 PM...07...14...00...ISS daily planning conference
Tue 04:43 PM...07...14...15...Dextre arm 1 stow
Tue 05:43 PM...07...15...15...Dextre arm 2 stow
Tue 06:23 PM...07...15...55...Module outfitting
Tue 06:43 PM...07...16...15...Dextre roll
Tue 06:53 PM...07...16...25...Dextre stow on lab module
Tue 07:53 PM...07...17...25...Crew meals begin
Tue 09:03 PM...07...18...35...SSRMS releases Dextre
Tue 09:08 PM...07...18...40...SLP grapple
Tue 09:18 PM...07...18...50...Spacesuit swap and reconfig
Tue 09:53 PM...07...19...25...SLP release
Tue 10:08 PM...07...19...40...SLP berthing
Tue 11:38 PM...07...21...10...SLP ungrapple
Tue 11:53 PM...07...21...25...SSRMS walkoff Harmony to mobile base system

03/19/08
Wed 12:28 AM...07...22...00...Crew off duty
Wed 01:28 AM...07...23...00...SSRMS releases node 2
Wed 01:38 AM...07...23...10...SSRMS translation
Wed 05:28 AM...08...03...00...STS crew sleep begins
Wed 01:28 PM...08...11...00...Crew wakeup
Wed 02:58 PM...08...12...30...ISS crew off duty
Wed 04:28 PM...08...14...00...STS crew off duty
Wed 09:08 PM...08...18...40...Joint crew news conference
Wed 09:28 PM...08...19...00...Joint crew meal
Wed 11:13 PM...08...20...45...T-RAD prep
Wed 11:58 PM...08...21...30...EVA-4: Tools configured

03/20/08
Thu 01:28 AM...08...23...00...EVA-4: Procedures review
Thu 04:38 AM...09...02...10...EVA-4: Airlock depress to 10.2 psi
Thu 05:28 AM...09...03...00...STS crew sleep begins

The mission's fourth spacewalk, by Behnken and Foreman, has two primary goals: Replacement of a faulty circuit breaker in the station's main power truss; and tests of the heat shield repair caulk gun. The former will require flight controllers to first power down critical station systems, including one of its two ammonia cooling loops.

Behnken will change out the circuit breaker, called a remote power control module, or RPCM, while Foreman moves to the Z1 truss atop the central Unity module to reconfigure an electrical panel to provide redundant power to one of the station's stabilizing gyroscopes while the powerdowns are in force.

With the RPCM installed, flight controllers will reactivate the powered down systems while Behnken and Foreman make their way back to the airlock to retrieve the equipment needed for the heat shield repair test. The work will be conducted on the bottom of the Destiny module, in view of the shuttle's payload bay cameras.

"We'll actually take a couple of bags of equipment with us, all the things that you might have in your garage if you were going to do some spackling and some dry-wall repair," Behnken said in a NASA interview. "We'll have that stuff in the bag. We'll have scrapers and brushes and all that sort of equipment. We'll also have some engineering equipment. If you wanted to really understand how well of a repair job you're doing, we're taking some thermometers and a camera and things like that so that we can actually assess the progress of the repair material and our repair technique and see how we're doing with it.

The idea is to use the tool, called a tile repair ablator dispenser, or T-RAD, to fill in deliberately damaged heat shield tiles to find out if the repair material, STA-54, will set up and adhere properly in the vacuum and weightlessness of space.

"There are a number of different sizes and shapes of samples and really, this correlates to the different objectives we're trying to get out of this test," Scoville said. "Some of of our tests are going to be involving a study of the material itself, how it adheres to tile substrates, how it expands, if it bubbles, what sort of density it's going to have. Other objectives of this test are really to focus on how well the crew can operate and perform. It's one thing to be able to repair a very evenly machined sample. It's another thing to have a divot or pock mark that's been cut by an ice impact or foam damage. So we've modeled a couple of tile damage samples to represent things we've seen on previous missions or on ground testing.

"There's really one main reason why we're trying to perform this test," Scoville said. "On the ground, we were able to develop techniques in a vacuum chamber to see how the material would react and then we performed tests on NASA's zero gravity airplane to understand how the repair process works in a zero gravity environment, albeit for a short period of time. But being able to combine both the vacuum and the zero gravity aspects of these together is what we're trying to figure out here."

When the two compounds making up STA-54 are mixed in the gun applicator, a chemical reaction causes bubbles to form. On Earth, those bubbles typically rise to the top. In space, they may be more evenly distributed throughout the material. This is a critical question because it could affect the material's ability to protect damaged tiles from the heat of re-entry.

"One of the big questions we have, in zero gravity are those bubbles going to rise to the surface or are they going to act more like a bread loaf as it bakes with the gas expanding in the material and being evenly distributed bubbles that then cause the surface to rise up over the top?" Scoville explained.

"The surface smoothness is a big key in understanding how this will react during a re-entry scenario. If you have a lot of bubbles and expanded ridges and what not, this can disrupt the airflow ... and cause a turbulent flow transition, which can cause downstream heating and damage the orbiter on re-entry. So being able to understand how this material's going to react and expand and what we can do to control that is really one of our primary objectives of this test."


DATE/EDT.......DD...HH...MM...EVENT

03/20/08
Thu 01:28 PM...09...11...00...Crew wakeup
Thu 02:28 PM...09...12...00...EVA-4: 14.7 psi repress/hygiene break
Thu 03:03 PM...09...12...35...EVA-4: Airlock depress to 10.2 psi
Thu 03:23 PM...09...12...55...EVA-4: Campout EVA preps
Thu 04:53 PM...09...14...25...EVA-4: Spacesuit purge
Thu 05:08 PM...09...14...40...EVA-4: Spacesuit prebreathe
Thu 05:58 PM...09...15...30...EVA-4: Crew lock depressurization
Thu 06:28 PM...09...16...00...EVA-4: Spacesuits to battery power
Thu 06:33 PM...09...16...05...EVA-4: Airlock egress
Thu 06:53 PM...09...16...25...EVA-4: Setup
Thu 06:58 PM...09...16...30...EVA-4 (Behnken): RPCM replacement
Thu 06:58 PM...09...16...30...EVA-4 (Foreman): Z1 patch panel reconfig
Thu 07:28 PM...09...17...00...EVA-4: T-RAD worksite setup
Thu 08:48 PM...09...18...20...EVA-4: T-RAD demonstration
Thu 10:33 PM...09...20...05...EVA-4: Tool cleanup
Thu 11:38 PM...09...21...10...EVA-4: Cleanup

03/21/08
Fri 12:38 AM...09...22...10...EVA-4: Airlock ingress
Fri 12:58 AM...09...22...30...EVA-4: Airlock repressurization
Fri 01:13 AM...09...22...45...Spacesuit servicing
Fri 04:58 AM...10...02...30...ISS crew sleep begins
Fri 05:28 AM...10...03...00...STS crew sleep begins

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