A piano-sized spacecraft blasted off Thursday on a 3-billion-mile (4.8-billion-kilometer) journey to study Pluto, the solar system’s last unexplored planet, and examine a mysterious zone of icy objects at the outer edges of the planetary system.
The New Horizons probe lifted off from the Cape Canaveral Air Force Station at 2 p.m. ET, quickly reaching speeds of 36,000 mph (58,000 kilometers per hour), nearly 100 times faster than a jetliner.
“We have ignition and liftoff of NASA’s New Horizons spacecraft on a decade-long voyage to visit the planet Pluto and then beyond,” said NASA commentator Bruce Buckingham.
It was the swiftest spacecraft ever launched, due to reach the orbit of Earth’s moon in nine hours and pass by Jupiter in just over a year.
The distance involved means scientists won’t be able to receive data on Pluto until at least July 2015, the earliest the mission is expected to arrive.
Delayed for two days
The launch had to be scrubbed twice — first because of strong winds Tuesday at the launch pad, and then because of a power outage Wednesday at the spacecraft’s control center in Maryland. Thursday's countdown was held an extra half-hour at the T-minus-4-minute mark while NASA waited for low clouds to clear, putting scientists on the edge of their seats.
“It looked beautiful,” said one of the mission scientists, Ralph McNutt Jr. of the Johns Hopkins University of Applied Physics Laboratory. “I was getting a little bit antsy.”
The launch drew attention from opponents of nuclear power because the spacecraft is powered by 24 pounds of plutonium, whose natural radioactive decay will generate electricity for the probe’s instruments.
NASA and the Department of Energy had 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 and 33 air samplers and monitors. No problems were reported during the ascent.
Last unexplored planet
A successful journey to Pluto would complete an exploration of the planets started by NASA in the early 1960s with unmanned missions to observe Mars, Mercury and Venus.
Pluto is the only planet discovered by a U.S. citizen, though some astronomers dispute Pluto’s right to be called a planet. It 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.
Pluto is the brightest body in a zone of the solar system known as the Kuiper Belt, which is 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 New Horizons spacecraft was launched on an Atlas 5 rocket, NASA’s most powerful launch vehicle. Some NASA safety managers had raised concerns about the rocket’s fuel tank, because a similar test tank failed a factory pressure evaluation. The decision was made to fly since the flight tank was in pristine condition and had no signs of any defects like the ones found on the test tank.
MSNBC.com contributed to this report.