NASA has postponed the launch of space shuttle Endeavour until Monday due to technical problems, Xinhua reported.
"Shuttle Endeavour's launch now no earlier than Monday at 2.33 p.m. EDT (1833 GMT)," NASA said Friday. "Engineers need that time to troubleshoot an issue that resulted in today's launch scrub."
During Friday's countdown, engineers detected a failure in one of two heater circuits associated with Auxiliary Power Unit (APU) 1. Heaters are required to keep the APUs' hydrazine from freezing on orbit.
Endeavour's 14-day mission will deliver the Alpha Magnetic Spectrometer-2 (AMS) to the International Space Station.
AMS, a particle physics detector, is designed to search for various types of unusual matter by measuring cosmic rays.
Its experiments are designed to help researchers study the formation of the universe and search for evidence of dark matter, strange matter and antimatter.
The mission will feature four spacewalks to do maintenance work and install new components. These are the last scheduled spacewalks by shuttle crew members.
Endeavour, which has been promised to the California Science Centre in Los Angeles upon its return, was the replacement ship for Challenger, which was lost in a 1986 explosion as it ascended over the Atlantic that killed seven astronauts.
It will be the second of NASA's three surviving shuttles to be retired. Sister ship Discovery, which will be transferred to the Smithsonian National Air and Space Museum, completed its last flight in March.
Atlantis' final launch is scheduled for June 28. When the US space shuttle programme officially ends later this year, the Russian space programme's Soyuz capsule will be the only method for transporting astronauts to and from the station.