ISS crew begins grappling and unbolting

Wearing yellow construction hats, the crew of the International Space Station began robotically moving a pressurized mating adapter, or docking port, at 5:30 a.m. EDT today to make room for the Harmony node, which will arrive in late October aboard shuttle Discovery.

Flight Engineers Clay Anderson and Oleg Kotov prepared to grapple the PMA-3 with the Canada arm II. Their hats were delivered by the Endeavour crew, which visited the ISS this month during STS-118.

Unbolting the PMA-3 had begun by 6:10 a.m. EDT.

The nearly six-hour operation will relocate the 2,607-pound docking port 90 degrees to a nadir, or earth-facing position, to allow the International Space Station to expand.

"This is a pretty major milestone for us," said NASA spokeswoman Lynnette Madison. "This is just one part of the whole assembly process."

The Harmony eventually will anchor the European and Japanese laboratories, which have been held at Kennedy Space Center due to delays in shuttle flights.

Watch The Flame Trench for coverage of the relocation operation.

Click here to see the ISS elements.