Vesta Protoplanet Will Capture Spacecraft In Mid July
NASA's Dawn spacecraft has obtained its first image of the giant
asteroid Vesta, which will help fine-tune navigation during its
approach. Dawn expects to achieve orbit around Vesta on July 16,
when the asteroid is about 117 million miles from Earth. The image
from Dawn's framing cameras was taken on May 3 when the spacecraft
began its approach and was approximately 752,000 miles from Vesta.
The asteroid appears as a small, bright pearl against a background
of stars. Vesta also is known as a protoplanet, because it is a
large body that almost formed into a planet.
Vesta NASA Image
"After plying the seas of space for more than a billion miles,
the Dawn team finally spotted its target," said Carol Raymond,
Dawn's deputy principal investigator at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, CA. "This first image hints of
detailed portraits to come from Dawn's upcoming visit."
Vesta is 330 miles in diameter and the second most massive
object in the asteroid belt. Ground- and space-based telescopes
obtained images of the bright orb for about two centuries, but with
little surface detail. Mission managers expect Vesta's gravity to
capture Dawn in orbit on July 16. To enter orbit, Dawn must match
the asteroid's path around the sun, which requires very precise
knowledge of the body's location and speed. By analyzing where
Vesta appears relative to stars in framing camera images,
navigators will pin down its location and enable engineers to
refine the spacecraft's trajectory.
Enhanced Image Shows More True Representation Of Vesta's
Size NASA Image
Dawn will start collecting science data in early August at an
altitude of approximately 1,700 miles (2,700 km) above the
asteroid's surface. As the spacecraft gets closer, it will snap
multi-angle images allowing scientists to produce topographic maps.
Dawn will later orbit at approximately 120 miles (200 km) to
perform other measurements and obtain closer shots of parts of the
surface. Dawn will remain in orbit around Vesta for one year. After
another long cruise phase, Dawn will arrive in 2015 at its second
destination, Ceres, an even more massive body in the asteroid
belt.
Gathering information about these two icons of the asteroid belt
will help scientists unlock the secrets of our solar system's early
history. The mission will compare and contrast the two giant
asteroids shaped by different forces. Dawn's science instruments
will measure surface composition, topography and texture. Dawn also
will measure the tug of gravity from Vesta and Ceres to learn more
about their internal structures. The spacecraft's full odyssey will
take it on a 3-billion-mile (5-billion-km) journey, which began
with its launch in September 2007.