The Dawn space probe's five billion km journey to the asteroid belt between Mars and Jupiter will begin a day later than planned, the US space agency NASA announced.
The spacecraft's launch aboard a United Launch Alliance Delta II rocket has been postponed from Wednesday until Thursday morning. The blastoff is now scheduled for a launch window of 7.20 a.m. to 7.49 a.m. Thursday.
The postponement was made after weather Sunday delaying fuelling of the rocket on the launch pad at the Kennedy Space Centre at Cape Canaveral, Florida. NASA has been trying to launch the robotic probe for months but has made several delays due to bad weather.
The 1.6 metres long, 747 kg craft is headed for the dwarf planet Ceres and the asteroid Vesta, which are both significantly smaller than Earth's moon.
The rocky objects date to the time when planets were forming in the solar system and could be an especially rich source of information for scientists.