Jupiter-bound spacecraft makes key maneuver
A Jupiter-bound spacecraftsuccessfully fired its engine Thursday in the first of two crucial maneuversintended to bring it toward Earth for a momentum-gathering fly-by.
NASA officials said the Juno spacecraft, which is about 300million miles (482 million kilometers) from earth, fired its main engine forjust short of 30 minutes.
Along with another engine firing set for next week, themaneuver is intended to direct Juno toward Earth's orbit for a 2013 fly-by,where it will use the planet's gravity to accelerate toward the outer solarsystem.
Launched last year, Juno is zooming toward an encounter withthe giant gas planet in 2016.
More than half a dozen spacecraft have visited the solarsystem's largest planet since the 1970s, but Juno promises to venture closerfor a deeper study into Jupiter's evolution.
By peering through Jupiter's dense clouds and mapping itsmagnetic and gravity fields, scientists hope to better understand how the solarsystem formed.
The $1.1 billion mission is managed by NASA's Jet PropulsionLaboratory.
Soon after launch, it glanced back and snapped a rarepicture of Earth and the moon.
Since the rocket that carried Juno was not powerful enoughto boost it directly to its destination, it has to cruise out to space andswing back next year to use the Earth as a slingshot to push it toward Jupiter.
The back-to-back burns were needed to put Juno on course tofly by Earth at an altitude of some 300 miles (482 million kilometers).
To prepare for Thursday's engine burn, the spacecraft's fueltanks were pressurized and its batteries were fully charged.
Once in orbit around Jupiter, Juno will circle the poles 33times and use instruments to track the abundance of water and oxygen in theatmosphere, and determine whether the planet's core is solid or gaseous.
Juno is the first solar-powered spacecraft to venture so farfrom the sun. It is equipped with three solar panels, each the size of atractor-trailer.
Juno is designed to study Jupiter for a year and thendeliberately crash into the planet so that it won't pose any threat ofbiological contamination to moons such as Europa, which scientists believe mayhave a liquid ocean beneath its surface.