NASA spacecraft flawlessly slipped into orbit around Ceres in the first visit to a dwarf planet

Ceres is seen from NASA's Dawn spacecraft just a few days before the mission achieved orbit around the previously unexplored dwarf planet. Photo / AP

A NASA spacecraft flawlessly slipped into orbit around Ceres in the first visit to a dwarf planet after a nearly eight-year journey.
The 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 mission chief engineer Marc Rayman at NASA's Jet Propulsion Laboratory, which manages the US$473 million mission.
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 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 onto the Texas-sized Ceres, the largest object in the asteroid belt.

The 4.8 billion kilometer 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.
"There are a lot of secrets that will be revealed," said mission scientist Lucy McFadden at NASA's Goddard Space Flight Center.
The spacecraft glided into place at 4.39am Friday and flight controllers received confirmation about an hour later. The maneuver occurred without a tense moment, unlike other captures that require braking to slow down.
"The real drama is exploring this alien, exotic world," Rayman said.
Dawn is currently in Ceres' shadows and won't take new pictures until it emerges in April, he said.
Discovered in 1801, Ceres - measuring 965 kilometers across - is named after the Roman goddess of agriculture and harvest. 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 neighbourhood with other similar-sized bodies.
With its massive solar wings spread out, Dawn is about the size of a tractor-trailer, measuring 20 meters from tip to tip.
Dawn carries an infrared spectrometer and a gamma ray and neutron detector to study the surface of Ceres from orbit. In the coming months, it will spiral down to within 378 kilometers of Ceres' surface where it will remain long after the mission is over.
"Every time we get closer, we see more things that make us scratch our heads," said mission scientist Mark Sykes, who heads the Planetary Science Institute in Arizona.
Dawn almost never made it out to the inner solar system. The mission endured funding-related project cancellations and launch delays before it received the green light to fly.
Dwarf planets lately have become the focus of exploration.
This summer, another NASA spacecraft "New Horizons" is set to make the first visit to Pluto, which was demoted to dwarf planet.

Five things to know about Ceres

Discovered in 1801, Ceres is named after the Roman goddess of agriculture and harvest. Photo / AP

The discovery
Ceres was spotted on New Year's Day in 1801 by Italian monk and astronomer Giuseppe Piazzi who was searching for a star. It was the first object discovered in the asteroid belt, a zone littered with rocky debris left over from the formation of the sun and planets 4 billion years ago.
The name
Piazzi named the object "Ceres Ferdinandea" after the Roman goddess of harvest and in honor of King Ferdinand IV of Naples and Sicily. Other astronomers shortened it to Ceres. The word cereal also has its origins in the goddess' name.
The chemical element cerium, discovered in 1803, was named after the celestial Ceres.
The identity crisis
Located about 250 million miles (400 million kilometers) from the sun, Ceres was deemed a comet when it was first discovered. Then it was promoted to a planet and later downgraded to an asteroid. Since 2006, it has been classified as a dwarf planet like Pluto, the one-time ninth planet. Dwarf planets are spherical in shape like planets, but they share the same celestial neighborhood with other similar-sized objects.
The bright spots
Ceres - with a diameter of about 965 kilometers - is thought to have a rocky core surrounded by an icy mantle. Long ago it might have harbored an underground ocean. As Dawn approached Ceres, it sent back images of a pair of puzzling bright spots inside a crater. Scientists think the shiny dots may be exposed ice or salt.
The mission
Launched in 2007 and powered by ion propulsion engines, Dawn will make the first close-ups of a dwarf planet, which won't begin until mid-April when the spacecraft emerges from Ceres' shadows.
Dawn will study Ceres for 16 months from varying altitudes, getting as close as 378 kilometers above Ceres' surface, or the distance of the International Space Station above Earth. The spacecraft will take sharper images of the mysterious spots and use its instruments to confirm whether Ceres' surface is still active and spewing plumes of water vapor.
This summer, another NASA spacecraft dubbed New Horizons will make the first visit to the dwarf planet Pluto.