NASA postponed the first three shuttle missions of 2007 to allow engineers extra weeks to fix or modify the launchers' troublesome external tanks.
Atlantis is scheduled for a March 16 blastoff, delayed from February 22, spokesman at the Kennedy Space Center in Cape Canaveral, Florida, Bruce Buckingham said on Friday.
Endeavour is scheduled to lift off June 28, while Atlantis is scheduled for a second mission on September 7, delays from June 11 and August 9 respectively, Buckingham added.
All three missions are tasked with further construction on the International Space Station (ISS).
NASA has two further 2007 shuttle missions to the ISS. One in October will deliver the Columbus Laboratory Module, built by the European Space Agency.
Another in December will deliver the pressurised section of the Kibo Japanese Experiment Logistics Module.
Discovery has one more flight this year, to blast off December 7 on an ISS construction mission.
NASA hopes to complete the ISS before its three-shuttle fleet is retired in 2010.
Atlantis carried out successful a 12-day mission in September at the ISS, the first such work on the half-finished space laboratory in more than four years.
The Atlantis mission was the third shuttle mission since the February 2003 Columbia disaster that killed seven astronauts.
Columbia was doomed by foam insulation that peeled off its external fuel tank during its launch and pierced its heat shield.