Juno Blasts Off for Planet Jupiter

BY Jenny Marder  August 5, 2011 at 11:16 AM EDT

For the first time in 16 years, NASA is heading back to planet Jupiter to look beyond the planet’s clouds and hopefully get some answers on the earliest days of the solar system.

At 12:25 p.m., the four-ton Juno spacecraft lifted off from Cape Canaveral atop an unmanned Atlas 5 rocket, embarking on a five-year, 1.7 billion-mile journey to the largest and probably oldest planet in the solar system. It is expected to pull into orbit around Jupiter on July 4, 2016.

The launch was delayed due to testing on the helium system of the rocket’s upper stage. Tests indicated that the vehicle is healthy.

The solar-powered Juno spacecraft will orbit Jupiter’s poles 30 times to probe the gas giant’s origins, structure, atmosphere and magnetosphere, according to NASA. Scientists hope the mission will help answer fundamental questions on how Jupiter formed and evolved.