Back to newsletter listDate:
Sat, June 07, 2008 09:07:11 AMFrom:
CBS Space News
Subject:
9a 6/7 Update: SARJ options debated; Japanese robot arm moves on tap
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CBS NEWS STS-124 STATUS REPORT: 42
Posted: 8:44 AM, 6/7/08
By William Harwood
CBS News Space Analyst
Changes and additions:
SR-40 (06/06/08): Logistics module mounted atop Kibo
SR-41 (06/06/08): Astronauts may collect grease sample from port SARJ; photos of wing panel requested
SR-42 (06/07/08): Japanese robot arm tests on tap
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8:44 AM, 6/7/08, Update: Japanese robot arm tests on tap
The Discovery astronauts plan to slightly unlimber the Kibo laboratory module's Japanese robot arm today and prepare for a third and final spacewalk Sunday to install a tank of pressurized nitrogen for the international space station's ammonia coolant loops.
Mission managers looking ahead to a spacewalk Sunday are still discussing whether to ask astronaut Michael Fossum to collect a sample of the grease he saw inside the station's left-side solar alpha rotary joint during the crew's second spacewalk Thursday.
The space station is equipped with two SARJ gears, one on either side of the lab's main power truss, that are designed to rotate outboard solar arrays like giant paddle wheels to track the sun. The right side SARJ has suffered considerable damage to the surfaces of the 10-foot-wide drive gear that are gripped by 12 three-roller trundle bearings. The left-side SARJ is operating normally, but Fossum spotted unusual buildups of grease during an inspection Thursday.
Engineers believe it may be coming from one or more of the trundle bearings the gear rolls through and it may be beneficial in slowing or preventing the sort of surface breakdown that has damaged the right-side gear. In any case, a sample might shed light on the issue.
"We're still discussing that," station Flight Director Emily Nelson said early today. "Each different technique you might use to get those samples has its own set of risks associated with it. So you've got to get comfortable with any or all of those risks."
One possible collection technique involves using a towel, "a dry cloth type of thing and wrapping it around a wrench and wiping the surface so you can get a little bit of it there on the wrench," Nelson said. "There are little droplets of the grease over near the teeth that are used by the gears to rotate the truss. Obviously, one of those droplets would be a nice sample to get but in the process of trying to get those, it might get lodged in the teeth, or it might float away and you can't catch it. So, there are a number of different methods we're talking about, we haven't agreed on any of them yet, partially because we need to know how much risk the program is willing to accept in our quest to get the sample."
Fossum will be in the area of the left-side SARJ during Sunday's spacewalk. But the joint "is going to be parked in a location different from where it was parked during EVA-2 just in order to have it in the right place for the other activities we have going on," Nelson said.
"So, we'd have to move it if we want to get it back to a place where he could access the same exact spot where he saw the grease before," she said. "That takes a lot of time, we won't be able to get it done while he's in the vicinity. So that's yet another discussion we have to have. He will be there about midway through the EVA, he'll be in a location where it would be really easy to go open the same cover. The problem is, the joint underneath is in a different place. So you open the cover, you look, you may not see a sample (of grease) there. So we have to go off and figure out will it be possible for us to both move the SARJ and get the crew back there so that we can get a sample from the same exact location? Or do we just take the risk and have him open it up when it's in a different place and hope that there will be a sample there to take?"
During today's work aboard the space station, the astronauts plan to continue outfitting and activating the Japanese Kibo lab module and re-establishing connections between Kibo and a smaller logistics module that was mounted atop the new laboratory on Friday.
Japanese astronaut Akihiko Hoshide also plans to slightly move Kibo's robot arm, which will be used in the future to manipulate externally mounted payloads and experiments, to give Fossum and Ronald Garan access to launch locks that will be removed during Sunday's spacewalk.
The arm "was too close in the launch configuration to the module itself so that Ron and Mike cannot access those launch locks," Hoshide said in a NASA interview. "So what we're trying to do is to deploy it just a little bit, and that's called the 'initial deploy,' so they can access. We'll have them take off the launch locks and then we'll do a final deploy so that's away from the module and then later in the mission we'll do a checkout of the arm, making sure that the brakes are working correctly and then move it into a storage configuration."
Three round-robin media interviews are scheduled to begin at 2:02 p.m. Hoshide and shuttle commander Mark Kelly will take a call from Japanese Prime Minister Yasuo Fukuda at 7:02 p.m.
Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision J of the NASA television schedule):
EDT........DD...HH...MM...EVENT
06/07/08
06:02 AM...06...13...00...Crew wakeup
08:02 AM...06...15...00...ISS daily planning conference
08:52 AM...06...15...50...Shuttle robot arm maneuver
09:02 AM...06...16...00...Airlock preps for EVA-3
09:27 AM...06...16...25...Middeck transfers
09:47 AM...06...16...45...EVA-3: Tools configured
10:27 AM...06...17...25...Kibo robot (JRMS) arm setup
11:17 AM...06...18...15...JRMS hold/release mechanism test
12:17 PM...06...19...15...JRMS initial deploy
01:32 PM...06...20...30...ISS crew meal
02:02 PM...06...21...00...Crew media interviews
02:22 PM...06...21...20...Shuttle crew meal
03:22 PM...06...22...20...Logistics module vestibule outfitting
05:02 PM...07...00...00...Station robot arm maneuver
05:27 PM...07...00...25...EVA-3: Procedures review
07:02 PM...07...02...00...Japanese VIP event
07:30 PM...07...02...28...Mission status briefing on NTV
07:57 PM...07...02...55...EVA-3: Mask pre-breathe/tool config
08:30 PM...07...03...28...VIP event replay with English translation; on NTV
08:42 PM...07...03...40...EVA-3: Airlock depress to 10.2 psi
09:02 PM...07...04...00...ISS crew sleep begins
09:32 PM...07...04...30...STS crew sleep begins
10:00 PM...07...04...58...Daily video highlights reel on NTV
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