The successful return of seven astronauts aboard NASA’s shuttle Atlantis kicked off a challenging construction year at the international space station (ISS).

Atlantis returned June 22 with veteran shuttle flyer Rick Sturckow at the helm to complete the STS-117 mission to deliver new trusses, solar arrays and one crew member to the ISS.

The 14-day mission of the Atlantis crew primed the orbital laboratory for the addition of a new connecting module and the European Space Agency’s Columbus laboratory later this year, as well as the first pieces of Japan’s three-segment Kibo module in early 2008.

To do that, NASA plans to launch the space shuttle Endeavour’s STS-118 mission

Aug. 9 to deliver a small spacer piece to the station’s starboard truss. Barbara Morgan, NASA’s first educator-astronaut, also will fly on that mission.

The shuttle Discovery follows on Oct. 20 to haul the Harmony connecting node to the ISS, with Atlantis again on tap to deliver Columbus in December. Each of those spaceflights, plus vital spacewalks and other assembly tasks by ISS crews in between them, must occur in order to continue the station’s construction.

“I think there [are] even bigger challenges in front of us as we continue assembly through the rest of this year,” said Bill Gerstenmaier, NASA’s associate administrator for space operations.

NASA plans at least 12 more shuttle flights through September 2010 to complete the space station’s construction. Two additional shuttle flights to ship cargo, spare parts and equipment to the ISS, also might fly. One additional flight to service the Hubble Space Telescope in September 2008, is also on tap.

said NASA and its international partners have taken key lessons from Atlantis’ STS-117 mission.

Engineers already have performed a series of pull tests on protective thermal blankets aboard Endeavour to ensure they are secure after a similar one peeled back from its left aft engine pod mount during Atlantis’ June 8 launch.

STS-117 spacewalker Danny Olivas secured the torn blanket with medical staples and pins. While an initial inspection found a slight gap between the blanket and surrounding heat tiles after landing, the anchor pins were still in place, NASA said.

Gerstenmaier said that a major crash of vital Russian control and navigation systems during the STS-117 mission also has paid off with lessons of the limits of current and future station hardware.

Engineers and ISS cosmonauts traced the computer problem to the failure of redundant surge-protector-like circuits within the computers, and then bypassed the fault using jumper cables. But it will likely take months to determine exactly what caused the circuits to fail in the first place.

During that time, ISS engineers will take a close look at similar computer systems aboard the Columbus laboratory and Europe’s unmanned station cargo ship, the Automated Transfer Vehicle, Gerstenmaier said.