Astronauts prep for mission's second spacewalk
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: November 21, 2009
Astronauts Michael Foreman and Randolph Bresnik, presumably still awaiting word on the birth of his second child, adopted a revised spacewalk preparation timeline Saturday after overnight false alarms interrupted their normal low-pressure sleep protocol.
Both astronauts were camping out in the space station's Quest airlock module at a reduced pressure of 10.2 pounds per square inch to help purge nitrogen from their bloodstreams before a planned spacewalk today.
But for a second night in a row, a false depressurization alarm, apparently triggered by an issue with a new Russian module, interrupted the preparation protocol and flight controllers told the astronauts they would instead exercise early today wearing oxygen masks to accomplish the required nitrogen purge.
The shuttle crew was allowed to sleep an extra half hour. As a result of the changes, the spacewalk now is expected to begin at 9:38 a.m. EST, about an hour and a half later than originally planned, and will last six hours instead of six-and-a-half.
"It was almost the exact same signature as we had (Thursday) night," Flight Director Jerry Jason said early today. "Once again, there was a false, rapid depress annunciation, the vehicle went through its automatic response, shut off all its ventilation, shut down a lot of the environmental equipment that's associated with it.
"It was a little different from the standpoint that we had two crew members in the airlock doing what we call the camp out for the EVA that's going to be happening (Saturday). The idea is by doing the camp out, we're cutting down the amount of time they have to prebreathe in their suits, breathing pure oxygen, in order to make sure all the nitrogen's out of their system so they won't suffer any bends effects when they go outside with the very low pressure in their suits."
As part of the station's automated response to the depressurization alarm, "we automatically equalized the airlock and the rest of the vehicle ... the idea being the crew can get out in the event of an emergency situation," Jason said. "That automatically happened."
Foreman and Bresnik immediately donned oxygen masks in an attempt to maintain the pre-spacewalk protocol.
"Unfortunately, because of the amount of time it took for us to get the equipment started back up in the station, we ended up having the crew take the masks off eventually and we're going to do something different for the EVA prep (Saturday), which we call the exercise pre-breathe protocol," Jason said.
"We'll get the crew on oxygen masks and ... we'll have them do some exercise. The surgeons already know what amount of exercise it takes to get the crew's metabolic rate up to 75 and 90 percent ... get the heart rate up, they'll be breathing pure oxygen, so that's another way we do to have them get the nitrogen out of their systems."
Adding a bit of drama to the proceedings, Bresnik's wife, Rebecca, had been scheduled to deliver the couple's second child, a girl, on Friday, two weeks ahead of her December due date. But as of Friday afternoon, Flight Director Brian Smith said he had not received an update and there was no mention in the crew's daily "execute package" of instructions and timeline changes.
This will be the 135th spacewalk devoted to station assembly and maintenance since construction began in 1998, the 16th so far this year and the second of three planned by the shuttle Discovery's crew,. Foreman will be making his fifth spacewalk while Bresnik will be making his first.
For identification purposes, Foreman's suit features solid red stripes around the legs while Bresnik's features broken stripes.
While Foreman and Bresnik are preparing for the crew's second spacewalk, Hobaugh and Melvin, operating the shuttle's robot arm, plan to pull a second spare parts pallet from its perch in the shuttle's cargo bay, the first step in a complex installation procedure.
The ELC-2 carrier holds a second spare control moment gyroscope on the pallet's upper surface, along with the 1,240-pound high-pressure oxygen tank and a cargo transport container housing spare remote power control module circuit breakers.
Another nitrogen tank assembly is bolted to ELC-2's lower side, along with another coolant system pump module and a spooled power line designed to play out and retract as the robot arm's mobile transporter moves along the front side of the station's solar power truss.
After Hobaugh and Melvin pull ELC-2 from the cargo bay, space station flight engineer Jeffrey Williams and commander Frank De Winne will lock on with the station's robot arm and maneuver it into place on the right side of the power truss. About halfway through the ELC-2 installation procedure, Foreman and Bresnik will begin the mission's second spacewalk.
"On EVA 2 we go outside and we get a couple of antennas that are going to be put on the outside of the Columbus (laboratory) module," Bresnik said in a NASA interview. "One of them is a (maritime navigation system) antenna that will go on the front side of the Columbus (module). The other one's essentially a ham radio antenna that'll go on the bottom side out of the starboard end of Columbus. So we're both going to go ahead and put the antennas in and string the cable, get it powered up.
"Then we head over and we're going to go ahead and take an antenna that is up on the starboard side that has to be maneuvered over to the port side to make room for the AMS, or Alpha Magnetic Spectrometer, that's going to come up on the final shuttle mission."
Once that work is done, Foreman and Bresnik will make their way to the upper side of the S3 starboard truss segment to deploy another cargo mounting mechanism like the one used to anchor the ELCs. That will allow "other flights to come up and put their hardware on the cupboard, or the shelf of the space station for later use," Bresnik said.
"And then the last thing we're going to do is we're going to take an antenna that helps with the wireless video system when we're doing EVAs, we're going to take and install an antenna that was inside the airlock, we're going to take it out with us and install it back on the S3, back where we're doing the (payload attach system) system and put that out there so we've got better coverage when we have our crew members going out to do an EVA."
The spacewalkers originally planned to spend a half hour on another get-ahead task, but because of the overnight alarms and the altered schedule, that work was deleted.
Here is an updated timeline of today's activity (in EST and mission elapsed time; includes revision G of the NASA television schedule):
EST........DD...HH...MM...EVENT 11/21/09 03:58 AM...04...13...30...Crew wakeup 05:13 AM...04...14...45...EVA-2: Exercise EVA prep 05:28 AM...04...15...00...ISS daily planning conference 06:48 AM...04...16...20...Shuttle arm (SRMS) unberths ELC-2 07:28 AM...04...17...00...Station arm (SSRMS) grapples ELC-2 07:38 AM...04...17...10...EVA-2: Spacesuit purge 07:43 AM...04...17...15...SRMS ungrapples ELC-2 07:53 AM...04...17...25...EVA-2: Spacesuit prebreathe 08:53 AM...04...18...25...EVA-2: Crew lock depressurization 09:38 AM...04...19...10...EVA-2: Spacesuits to battery power 09:48 AM...04...19...20...EVA-2: Airlock egress 09:43 AM...04...19...15...SSRMS installs ELC-2 10:08 AM...04...19...40...EVA-2: GATOR install 10:28 AM...04...20...00...SSRMS grapples MBS-1 11:23 AM...04...20...55...EVA-2: FPMU relocate 12:53 PM...04...22...25...EVA-2: S3 zenith PAS deploy 02:23 PM...04...23...55...EVA-2: CP1 WETA install 02:23 PM...04...23...55...SSRMS releases MBS-2 03:08 PM...05...40...00...EVA-2: Cleanup and ingress 03:38 PM...05...01...10...EVA-2: Airlock repressurization 03:53 PM...05...01...25...Spacesuit servicing 04:13 PM...05...01...45...Evening planning conference 06:28 PM...05...04...00...ISS crew sleep begins 06:58 PM...05...04...30...STS crew sleep begins 04:30 PM...05...02...02...Mission status briefing on NTV 06:28 PM...05...04...00...ISS crew sleep begins 06:58 PM...05...04...30...STS crew sleep begins 07:00 PM...05...04...32...Daily highlights