For the second day in a row, NASA scrubbed the launch of an unmanned spacecraft on a nine-year voyage to Pluto -- this time because a storm in Maryland on Wednesday knocked out power at a laboratory that will operate the probe.
NASA officials planned to make a third attempt today to launch the New Horizons probe.
High winds at the launchpad kept the spacecraft from lifting off Tuesday.
Scientists have been working for 17 years on the mission, and they were unfazed by the delays.
"Two or three days doesn't mean a hill of beans," said Alan Stern, principal investigator for the mission.
A storm in Laurel, Md., knocked out power at the Johns Hopkins University Applied Physics Laboratory.
"The air conditioning was off. The flight controllers were sitting there wiping sweat," Stern said. "If they were dealing with any spacecraft issues, which first day out of the box a lot of spacecraft have, you can't concentrate like that."
The space agency has until mid-February to send the spacecraft on its way.
The craft is about the size and shape of a grand piano. It will study Pluto as well as the frozen, sunless reaches of the solar system known as the Kuiper Belt. Scientists believe that studying the region can shed light on how the planets formed.