As work is underway in Central Florida to get ready for a new era in spaceflight, work also began in space Saturday morning, about 257 miles above the Earth.

Astronauts began a series of spacewalks that will transform the International Space Station and allow American crew vehicles to once again dock at the orbiting outpost.

At 7:45 a.m. Saturday, NASA astronauts Barry "Butch" Wilmore and Terry Virts began a new effort to get the ISS ready for the future.

Heard on NASA TV during the spacewalk: "It's just like in the pool, with the exception of that big, blue planet down there."

During the 6 1/2-hour spacewalk high above Earth, the astronauts were tasked with laying cables that will provide power and data for a new docking adapter to be installed later in 2015. That adaptor will allow Americans on SpaceX and Boeing's commercials vehicles to connect to the space station.

Saturday's spacewalk was the first of three scheduled in a span of nine days, and that's just the beginning of spacewalks scheduled this year to get the ISS ready for commercial crew vehicles.

"When you look at the longer term at what this is going to do for us in terms of meet our goals for commercial crews and commercial cargo vehicles going forward, it's going to be exciting, and it's just another step on that path to commercializing low-Earth orbit," said Kenneth Todd, NASA's International Space Station operations integration manager.

Hundreds of miles below, work is also being done on the ground in Brevard County to get ready for commercial launches. A groundbreaking ceremony at Cape Canaveral on Friday marked the beginning of construction on a crew access tower that will allow astronauts to board Boeing's CST-100 for a ride on United Launch Alliance's Atlas V rocket.

"All elements of our design are taken into consideration the human safety aspects of both the flight crew and the ground crew," said Howard Biegler, with the United Launch Alliance.

Both Boeing and SpaceX are slated to begin launching astronauts from the Space Coast starting in 2017, and NASA wants to make sure those commercial vehicles can dock or berth with the space station without issue.

Two more spacewalks are planned for the pair in the coming days: one on Wednesday — and the last on March 1.

Spacewalks come with danger. In 2013, for example, water filled the helmet of an Italian astronaut's spacesuit, nearly drowning him.

There was also concern over a fan pump not working on one of the astronauts' spacesuits, which caused the spacewalk to be delayed from Friday. NASA officials, however, were confident that the spacesuit would work just fine Saturday.

Altogether, Wilmore and Virts have 764 feet of cable to run outside the space station. The longest single stretch, for installation Saturday, was 43 feet.

"Broadening my resume," Virts observed as he started laying cable.

NASA considers this the most complicated cable-routing job in the 16-year history of the space station. Equally difficult will be running cable on the inside of the complex.

NASA is paying Boeing and SpaceX to build the capsules and fly them from Cape Canaveral, which hasn't seen a manned launch since the shuttles retired in 2011. Instead, Russia has done all the taxi work — for a steep price.

The first of two docking ports for the Boeing and SpaceX vessels, still under development, is due to arrive in June. Even more spacewalks will be needed to rig up everything.

There were so many cables — up to 10 on Saturday to deal with — that NASA color-coded them. That helped the spacewalkers only so much; they expected a lighter blue for one of the lines.

"I worked up a lather on that one," Wilmore informed Mission Control. After successfully attaching the first four cables, he added, "I've got to cool down."

It was the first spacewalk for Virts, who arrived at the space station in late November. He savored the moment as he floated out high above the South Pacific. "Pretty cool," he said.

Information from AP Aerospace Writer Marcia Dunn was used in this report.