US: After nearly seven years of travel, the international Cassini spacecraft is finally within striking distance of its heavenly destination: Saturn.
The US-European spacecraft was due to enter Saturn's orbit last night to begin a four-year tour of the giant planet, its shimmering rings and some of its 31 known moons.
"We're right on track," navigation team chief Mr Jeremy Jones told a press conference yesterday at NASA's Jet Propulsion Laboratory in Pasadena.
Cassini was programmed to pass through a gap between two of Saturn's rings, fire its rocket for 96 minutes to slow down, then descend back through the ring plane.
Cassini programme manager Mr Robert Mitchell called orbit insertion a "hair-greying" event, but he and other officials expressed confidence in a successful outcome.
The $2 billion mission was launched at Kennedy Space Centre on October 15th, 1997.
The 22-foot-long Cassini was too big to be launched on a direct trajectory to Saturn. So it was sent toward the inner solar system, where it received two gravity assists from Venus and one from Earth.
The Earth flyby gave Cassini enough of a boost for a December 2000 flyby of Jupiter, which in turn boosted it towards Saturn. On arrival Cassini will have travelled 2.2 billion miles.
It also carries a probe named Huygens that will be launched into the murky atmosphere of the moon Titan.
The frozen moon intrigues scientists because it may have many of the chemical compounds that existed on Earth before life began.
Scientists see the Saturn system as a model of the early solar system when the sun was surrounded by a disc of material. Studying it may increase understanding of how the planets formed.