CAPE CANAVERAL: NASA scrubs launch of Pluto mission spacecraft for second day

NASA scrubbed its launch of an unmanned spacecraft on a nine-year voyage to Pluto for the second day Wednesday, but this time weather in Maryland was to blame.

A storm in Laurel, Maryland, knocked out power at the John Hopkins University Applied Physics Laboratory, which is managing operations of the New Horizons spacecraft.

A decision on whether to try for a Thursday launch depended on whether backup power could be restored at the Maryland facility. That decision would be made late Wednesday, said Alan Stern, the mission's principal investigator. The space agency has until mid-February to launch the piano-sized spacecraft, but a launch in January would allow the spacecraft to use Jupiter's gravity to shave five years off the 3-billion-mile trip (5-billion-kilometer trip).

The launch of the New Horizons probe had been called off Tuesday afternoon when winds at the launch pad in Cape Canaveral exceeded the space agency's 38 mph (61 kph) flight restriction.

A successful journey to Pluto would complete an exploration of the planets that was started by NASA in the early 1960s with unmanned missions to observe Mars, Mercury and Venus. Pluto is an oddball icy dwarf unlike the rocky planets of Mercury, Venus, Earth and Mars and the gaseous planets of Jupiter, Saturn, Uranus and Neptune.

It also is the brightest body in a zone of the solar system known as the Kuiper Belt, made up of thousands of icy, rocky objects, including tiny planets whose development was stunted by unknown causes.

Scientists believe studying those "planetary embryos" can help them understand how planets were formed.

The planned launch has drawn attention from opponents of nuclear power because the spacecraft is powered by 24 pounds (11 kilograms) of plutonium, whose natural radioactive decay will generate electricity for the probe's instruments, the AP reports.

NASA and the Department of Energy estimated the probability of a launch accident that could release plutonium at 1 in 350. As a precaution, the agencies brought in 16 mobile field teams that can detect radiation, plus air samplers and monitors.

A.M.