Nasa spaceship nearing Jupiter

MIAMI: Juno, an unmanned Nasa spacecraft, is barrelling toward Jupiter on a $1.1 billion mission to circle the biggest planet in the solar system and shed new light on the origin of our planetary neighbourhood.

On July 4 and 5, the solar-powered vehicle -- about the size of a professional basketball court -- should plunge into Jupiter’s poisonous atmosphere to begin orbiting for a period of almost two years.

Jupiter is the fifth planet from the sun. Its atmosphere is made up of hydrogen and helium and packed with so much radiation that it would be more than 1,000 times the lethal level for a human.

The gas giant is also enshrouded in the strongest magnetic field in the solar system.

"Jupiter is a planet on steroids," said Juno principal investigator Scott Bolton, of the Southwest Research Institute in San Antonio, Texas. "Everything about it is extreme."

Jupiter is perhaps best known for its Great Red Spot, which is actually a massive storm, bigger than the Earth, that has been roiling for hundreds of years.