NASA’s Dawn spacecraft visits dwarf planet

LOS ANGELES – After a nearly eight-year journey, a NASA spacecraft on Friday flawlessly slipped into orbit around Ceres in the first visit to a dwarf planet.

The robotic Dawn craft will circle the dwarf planet for more than a year, exploring its surface and unraveling its mysteries.

“It went exactly the way we expected. Dawn gently, elegantly slid into Ceres’ gravitational embrace,” said Marc Rayman, chief engineer for the $473 million mission managed by NASA’s Jet Propulsion Laboratory in Pasadena.

Ceres is the second and final stop for Dawn, which launched in 2007 on a voyage to the main asteroid belt, a zone between Mars and Jupiter that’s littered with rocky leftovers from the formation of the sun and planets some 4 1/2 billion years ago.

Dawn will spend 16 months photographing the icy surface. It previously spent a year at Vesta exploring the asteroid and sending back stunning close-ups of its lumpy surface before cruising on to Ceres, the largest object in the asteroid belt.

The 3-billion mile trip was made possible by Dawn’s ion propulsion engines, which provide gentle yet constant acceleration and are more efficient than conventional thrusters.

As Dawn approached Ceres, it beamed back the best pictures ever taken of the dwarf planet. Some puzzling images revealed a pair of shiny patches inside a crater – signs of possible ice or salt.

Scientists hope to get a better glimpse of the spots when the spacecraft spirals closer to the surface. It’ll also study whether previously spotted plumes of water vapor continue to vent.

Discovered in 1801, Ceres measures 600 miles across – as wide as Texas – and has a rocky core. It was initially called a planet before it was demoted to an asteroid and later classified as a dwarf planet. Like planets, dwarf planets are spherical in shape, but they share the same celestial neighborhood with other similar-sized bodies.