The US space agency on Friday delayed by 24 hours until Monday the launch of its spacecraft Dawn due to set off on an eight-year mission to unlock the mysteries of the origins of our solar system. "The delay was prompted by difficulties with an aircraft that would gather data signals from the rocket during launch, and the availability of a tracking ship," NASA said on its website. The window for launching the unmanned craft would now be between 3:56 pm (1956 GMT) to 4:26 pm (2026 GMT) on Monday, July 9, the agency said. Dawn had been due to launch into space on Sunday on a voyage to examine two massive asteroids. NASA scientists said there were also concerns that fuel loading would not be completed in time on Friday at the Cape Canaveral Air Force base, in Florida, due to looming bad weather. Scientists hope the Dawn probe will shed light on the earliest moments in the birth of the solar system 4.6 billion years ago by examining the two celestial bodies Ceres and Vesta in the asteroid belt between Mars and Jupiter, Dawn is scheduled to enter orbit around Vesta in October 2011, proceed to Ceres in May 2012 and then begin orbiting Ceres in February 2015 -- travelling a total distance of 5.1 billion kilometers. The National Aeronautics and Space Administration (NASA) says the mission should provide a better understanding of the building blocks that formed the terrestrial planets and how the two "protoplanets" followed different evolutionary paths. The deep-space explorer, measuring 1.64 meters (yards) long and 1.27 meters (yards) wide when its solar array is retracted, is equipped with a high-definition camera and two spectrometers to study the two massive asteroids. Ceres, discovered in 1801, has a spherical shape and has a diameter of about 960 kilometers (596 miles). Scientists believe it may have a layer of thick ice under its crust, covering a rocky core. Vesta, discovered in 1807, is smaller than Ceres but the third largest asteroid in the solar system. With a diameter of 520 kilometers (323 miles), Vesta has a rocky surface without a trace of water and a hot interior. After having cancelled the Dawn project previously, NASA revived the mission in 2006 after an investment of 449 million dollars. It is the ninth mission out of 10 planned in NASA`s Discovery program that employs unmanned vehicles to explore space, often focusing on asteroids.