Despite
some finicky bolts, astronauts aboard the International Space Station (ISS) moved
an old docking port to a new parking spot Thursday, clearing a berth for the
arrival of a brand new module later this year.
Working
from inside the space station, Expedition 15 commander Fyodor Yurchikhin and
flight engineers Oleg Kotov and Clayton Anderson successfully moved
the docking port from its port-side perch on NASA's Unity module to
an Earth-facing berth. The relocation frees up space for the new Harmony connecting
node due at the ISS in October.
"Lucia, you and everyone else might want to go out and grab
lunch while this is going on," Anderson told spacecraft communicator Lucia
McCullough in Mission Control during the slow, delicate move of the docking
port known as Pressurized Mating Adapter-3 (PMA-3).
A series of
intermittent fault messages delayed PMA-3's relocation by about an hour when
three of the 16 bolts securing the docking port in place returned errors. But
Mission Control determined that the glitch would not impact the relocation or
the Harmony node's installation later this year.
"There's
some speculation that the length of time PMA-3 spent at that left side location
may have played a role in those fault indications," NASA commentator John
Ira Petty said of the docking port, which sat unmoved for more than six years before
today.
The short trip
for PMA-3 cleared a critical hurdle for the space station's construction.
NASA plans
to launch the shuttle Discovery's STS-120 mission on Oct. 23 to deliver the new Harmony node,
which will serve as the foundation for future international laboratories at the
ISS. But Harmony must be temporarily installed at Unity's port side berth since
the station's 57-foot (17-meter) robotic arm would not have enough reach to attach
a docking port at the tip of new node if it were stationed at an Earth-facing
location, NASA said.
The three
Expedition 15 astronauts donned bright
yellow hard hats emblazoned with their mission emblem for Thursday's
orbital work. The gag construction helmets were delivered to the ISS earlier
this month by the STS-118
astronaut crew of NASA's space shuttle Endeavour.
"We
like the hats," McCullough told the Expedition 15 crew.
Anderson,
assisted by Kotov, wielded the station's robotic arm during PMA-3's move and
kept the massive docking port within a few feet of the ISS. Yurchikhin,
meanwhile, oversaw the bolt latching systems to alternately free and secure the
module during its relocation. The astronauts plucked PMA-3 free of Unity at
8:23 a.m. EDT (1223 GMT) and successfully reattached the port to its new berth
at 9:07 a.m. EDT (1307 GMT).
Ready
for Harmony
The space
station's three conical Pressurized Mating Adapters serve as either connecting
tunnels between ISS modules or docking ports for NASA shuttles and the agency's
future
Orion Crew Exploration Vehicles.
PMA-1
connects the Unity node with the Russian Federal Space Agency's Zarya control
module, while PMA-2 sits at the front of the station's U.S. Destiny laboratory
as a shuttle docking port. PMA-3 weighs 2,607 pounds (1,183 kilograms) with a
diameter that tapers from 6.2 feet (1.9 meters) at its widest down to 4.5 feet
(1.8 meters) at the narrow point.
The docking
ports are attached to the ISS by way of a Common Berthing Mechanism equipped with
16 remote controlled bolts that Yurchikhin loosened in sequence to free PMA-3.
"It's
a bit like changing the lug nuts on a tire," NASA's lead Expedition 15
flight director Bob Dempsey told SPACE.com of the ISS bolts. "You
kind of do them in groups to make sure the forces are equal."
Thursday's
PMA-3 relocation marked a return home of sorts for the seven-year-old docking
port.
Astronauts
first installed the module to Unity's Earth-facing berth in October 2000 during
NASA's STS-92 mission, after which it served shuttle docking port. But in March
2001, astronauts moved PMA-3 to Unity's port side berth where it most recently
served as a storage closet.
The module was
also not completely empty during its short trip. Mission managers opted to
leave a large spare part for the space station's robotic arm inside simply
because there wasn't enough room inside the outpost to store it.
"We
decided to leave it in there with straps, so we had to make sure that the item
was secured very tightly," said Dempsey, adding that the astronauts would
take extra care to avoid exposing PMA-3 to high temperatures that would loosen
the glue on the straps and send the massive piece of hardware drifting out into
space. "That would be very bad."
Dempsey
praised the cooperation between Expedition 15's Russian and American
astronauts. Their mission has marked the first time NASA-controlled components
like the station's Canadian-built robotic arm have been wielded by Russian
cosmonauts. In the past, only NASA astronauts oversaw operating the station's
Common Berthing Mechanisms and Canadian-built robotic arm, Dempsey said.
"This
is one of the first crews I've seen that's been truly integrated," Dempsey
said. "There're really no boundaries here and it's great to see them meld
together."
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