A new countdown has begun on the International Space Station: It's T-minus two days and counting – give or take a few hours – for some of the most stunning views astronauts have ever had of Earth.
By late Wednesday or Thursday, astronauts on the station should be able to open the shutters of a $27-million, seven-windowed cupola, now snugly bolted to its proper spot on a new space-station segment astronauts installed during the past week.
Both were delivered by the space shuttle Endeavour and its six-member crew during the shuttle's current mission, now at its halfway point.
The cupola in essence is the station's version of a seven-pane bay window. In its workaday role, it provides a place where crew members inside can provide an extra set of eyes to help colleagues on spacewalks. It also hosts a second set of controls the crew can use to operate the station's robotic arm.
But the cupola – nearly 10 feet across at its base and some 5 feet deep – also "is really one of the most spectacular viewing platforms that we will have had in space," says Kwatsi Alibaruho, the lead shuttle flight director for this mission. "We're eagerly awaiting the release of the shutters and the first views."
Anticipation of those first views has come after a sometimes frustrating installation effort.
Initially, the cupola was attached to one end of the new segment, Tranquility, to ensure that both elements would fit inside Endeavour's payload bay. But as astronauts worked on Sunday to loosen the bolts holding the cupola in that spot, several bolts balked.
After engineers on the ground analyzed the problem, they gave shuttle commander Jeffery Williams the OK to apply a more-forceful twist, which did the trick. In addition, loose wiring initially looked as though it might interfere with the cupola's final installation, although engineers also were able to determine that the wires posed no problem.
The tighter-than-expected bolts likely resulted from technicians on the ground wanting to make sure that the hardware connecting the two wouldn't be damaged during the intense stresses of launch.
"It was a hard-fought victory," Mr. Alibaruho said during a briefing with reporters this morning.
In addition, crew members also declared victory over a balky urine processor -- which purifies waste for reuse as drinking water. The ability to reprocess waste water of all kinds is important for supporting a six-member space station crew. In addition, astronauts appear to have gotten the upper hand over an oxygen generator that was giving the crew trouble.
The next spacewalk for shuttle crew members is scheduled for Wednesday, when two astronauts will finished hooking Tranquility up to the station's external cooling system. They also will remove locks that held the cupola's shutters in place during launch.
In the meantime, other crew members will begin installing the robotic-arm work station in the cupola, as well as moving life-support equipment currently housed in the US laboratory to Tranquility. Mission managers have extended the trip by one day to accommodate these tasks.
By the time shuttle astronauts bid their farewells to the station crew on Friday, the station will have reached what Alibaruho calls a great milestone. The core assembly tasks for the US segments of the station essentially will be complete, he says.
With only four missions remaining after Endeavour and its crew end their 14-day trip on Sunday, with a scheduled night landing at the Kennedy Space Center, the imminent end of the shuttle program is not lost on mission managers or astronauts.
"This crew has done a very good job of taking the time to enjoy and reflect on the opportunities that they have in space right now," Alibaruho says. The sentiments were reflected in a phone call Alibaruho says he took from shuttle pilot Terry Virts indicating "that they were really taking it all in and really enjoying their work time as well as their time off."
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