The launch of Nasa's Dawn space probe, which will explore the asteroid belt between Mars and Jupiter, has been delayed until Sunday.
Thunder and lightening warnings have been issued, meaning the launch rocket cannot be fuelled for safety reasons. The launch was due to go off tomorrow but has now been pushed back to Sunday afternoon, although weather forecasts for that time slot do not look good either.
"A lightning advisory early Thursday interrupted fuelling of the Delta II second stage rocket," said Nasa in a statement.
"Also, the temperature of the vehicle's second stage was too warm for the fueling process to begin. However, the fairing temperature has been lowered so that another attempt can be made Friday, July 6, pending acceptable weather."
Dawn's mission is to travel to the two of the largest objects in the asteroid belt, Ceres and Vesta, and the probe will send back vital information about the formation of the planets in the solar system. It is thought the asteroid belt may be an accumulation of matter that couldn't reach critical mass to join together to form a planetary body.
Ceres is thought to be covered by a thick layer of ice up to 120 km deep, with the possibility of liquid water underneath. Vesta is a dry asteroid, but its diameter of 530km means it alone accounts for around 10 percent of the total mass of the asteroid belt.
If the probe launches successfully it will reach Vesta in late 2011 and go into orbit for seven months. It will then set of for Ceres, arriving in February 2015.
Nasa space probe launch delayed
By Iain Thomson on Jul 9, 2007 4:56PM