Nasa launches Juno robot to explore Jupiter

The rocket carrying Nasa’s Juno spacecraft lifted off at 12:25 pm (1625 GMT), the first step in a five-year, 716-million km journey to the largest planet in the solar system.

Launch was delayed almost an hour while United Launch Alliance, a Boeing-Lockheed Martin joint venture that builds and flies Atlas and Delta rockets for Nasa, the military and commercial customers, fixed a technical problem with ground support equipment that supplies a helium purge to the rocket.

Upon arrival in July 2016, Juno is to spend a year in an unprecedented polar orbit around the giant planet, measuring its water content, mapping its magnetic fields and searching for signs of a solid core. With more than twice the mass than all its sibling planets combined, Jupiter is believed to hold a key piece to the puzzle of how the planets formed some 4.65 billion years ago from the gas and dust left over after the birth of the sun.

“We are really looking for the recipe for planet formation,” said Juno scientist Scott Bolton, with the Southwest Research Institute in San Antonio, Texas. “We are going after the ingredients of Jupiter by getting the water abundance as well as very precise measurements of the gravity field that will help us understand whether there’s a core of heavy elements or a core of rocks in the middle of Jupiter,” he said.

The measurements will help scientists discriminate among theories about what the early solar system looked like and how Jupiter was created.

To make its observations, Juno will soar as close as  5,000 km above Jupiter’s cloud tops, the first spacecraft to fly inside the planet’s radiation belts.