Astronauts aboard the International Space Station on Monday added an observation deck that will give residents of the orbital outpost a panoramic view of the station and Earth below. After struggling with some jammed bolts, crew of the shuttle Endeavour used the station's robot arm to connect the Italian-made cupola to the newly delivered Tranquility connecting hub. "It's going to help when we do robotic operations," Endeavour astronaut Terry Virts said in an in-flight interview. "It'll give us a big view in a lot of different directions." Robot arm operators aboard the station now rely solely on camera views, with no direct view outside. With Tranquility and the viewing port installed, major construction on the $100 billion orbital outpost is complete. NASA has only four more space shuttle missions scheduled to ferry spare parts and supplies to the station, a project of 16 nations that has been under construction since 1998. Endeavour and six astronauts blasted off on Feb. 8 for a 13-day construction mission. NASA added an extra day to the flight to give the station crew help getting the new modules ready for use. Endeavour is due back at the Kennedy Space Center in Florida on Sunday, Reuters reported.