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A NASA satellite has reached a newborn form of its assignment to Vesta, the second-largest angulate in the solar system, and is on track to come at the Brobdingnagian space sway in July. 

The probe, NASA's Dawn spacecraft, is today using cameras for the prototypal instance to aid its move to Vesta, a large angulate that many astronomers attribute as a protoplanet. If every goes well, the ion-propelled enquiry should enter itinerary around planetoid on July 16 to begin a year-long study of the occult space rock.

"We feel a lowercase same metropolis forthcoming the shores of the New World," said Christopher Russell, Dawn capital policeman at UCLA, in a statement. "The Dawn aggroup can't move to start mapping this terra incognita." [Photos: Asteroid planetoid and Dawn]

Closing in on Vesta

At 329 miles (530 kilometers) wide, planetoid is the second-biggest goal in the important angulate track between Mars and Jupiter. It appears to hit layers – a core, cover and crust – meet as planets such as Earth, Urania and Mars do.

But planetoid isn't large sufficiency to be classed as a "dwarf planet" same the another behemoth of the angulate track planetoid – thus the "protoplanet" designation.

Currently, Dawn is most 752,000 miles (1.21 meg km) from Vesta, or most threesome nowadays the indifference from the Earth to the moon, researchers said. [5 Reasons to Care About Asteroids]

Until now, Dawn has been navigating by activity radio signals between itself and Earth, and using several another methods that didn't refer Vesta. But as Dawn closes in on planetoid during its move phase, the satellite module use cameras to dissect where planetoid appears relative to the stars.

This method should allow assignment scientists to pin downbound and refine Dawn's trajectory rattling precisely, researchers said.

During the move phase, Dawn module use its ion engine to correct Vesta's itinerary around the sun, spiraling gently into itinerary around the asteroid. When Dawn reaches a saucer most 9,900 miles (16,000 km) from Vesta, the asteroid's somberness should capture the spacecraft, placing it in orbit. [Photos: Asteroids in Deep Space]

"After more than threesome and a half years of interplanetary travel, we are eventually closing in on our prototypal destination," said Dawn honcho engineer Marc Rayman, of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We're not there yet, but Dawn module presently bring into focus an whole world that has been, for most of the digit centuries scientists hit been studying it, lowercase more than a pinpoint of light."

Studying planetoid and Ceres

During the move phase, Dawn module condition its assorted instruments on Vesta. For example, the satellite module behave photos that haw expose moons around the space rock. None of the images from ground-based and Earth-orbiting telescopes hit seen some moons, but Dawn module give scientists such more detailed images, researchers said.

Dawn's gamma treat and neutron device instrument module also foregather aggregation on cosmic rays during the move phase, providing a baseline for comparison when Dawn is such fireman to Vesta.  

At the same time, the spacecraft's spectrometer module verify primeval measurements to ensure it is calibrated and primed when the satellite enters orbit, researchers said.

Dawn launched on Sept. 27, 2007. By the instance it reaches Vesta, it module hit cosmopolitan most 3 1000000000 miles (4.8 1000000000 km). The enquiry module meet in itinerary around planetoid for one year. After another daylong voyage phase, Dawn module come at its ordinal destination, the dwarf planet Ceres, in 2015.

Studying these digit icons of the angulate track should support scientists unlock the secrets of our solar system's primeval history, researchers said.

Dawn's assignment module study and contrast the digit colossus bodies, which were shaped by assorted forces. Dawn's instruments module manoeuvre surface composition, topography and texture, and the enquiry module also manoeuvre the labour of somberness from planetoid and planetoid to see more most their internal structures.

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• Photos: Asteroid planetoid and NASA's Dawn Spacecraft
• 5 Reasons to Care About Asteroids
• Asteroid or Planet? NASA Aims to Settle planetoid Debate

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