The launch of a NASA satellite designed to study atmospheric carbon dioxide has been rescheduled for early Wednesday.
A Delta 2 rocket carrying the satellite had been scheduled to lift off early Tuesday from Vandenberg Air Force Base, California.
NASA says the countdown stopped at 46 seconds because of the failure of a water flow system that suppresses acoustic energy and protects a launch pad flame duct.
The agency says it replaced a bad valve, and the launch will now take place during a 30-second window opening at 0956 GMT.
The satellite, dubbed Orbiting Carbon Observatory-2, is a replacement for a satellite destroyed during a failed launch in 2009.
The $468 million mission will collect global measurements of CO2 in Earth's atmosphere, the main driver of climate change.