Scientists use Dawn to pull back the veil on Vesta
BY STEPHEN CLARK
Posted: April 26, 2012
Since being tugged into orbit around asteroid Vesta last July, NASA's Dawn spacecraft has pulled back the curtain on the object's surface characteristics, internal structure and wild temperature swings, revealing Vesta to be a complex world much like a miniature planet.
The spacecraft will also be stationed in a high-altitude mapping orbit for longer than planned this summer.
"We are leveraging our smooth and successful operations at Vesta to provide for even more scientific discoveries for NASA and the world." said Robert Mase, Dawn project manager based at NASA's Jet Propulsion Laboratory. "This extra time will allow us to extend our scientific investigation and learn more about this mysterious world."
Financial and schedule reserves were built in to Dawn's mission to cover any problems at Vesta, but the mission has not encountered any major problems, permitting managers to extend the craft's stay at Vesta from July until August.
Dawn will depart Vesta in late summer, using its ion propulsion system to reshape its trajectory and reach the dwarf planet Ceres in February 2015.
"After more than nine months at Vesta, Dawn's suite of instruments has enabled us to peel back the layers of mystery that have surrounded this giant asteroid since humankind first saw it as just a bright spot in the night sky," said Carol Raymond, Dawn deputy principal investigator at JPL. "We are closing in on the giant asteroid's secrets."
Vesta is roughly spherical in shape, measuring about 359 miles by 285 miles. First identified in 1807, Vesta was the fourth asteroid ever discovered.
Images from Dawn reflect Vesta's diverse history, which included volcanism and collisions with other asteroids. Both types of processes shaped the Vesta surface researchers see today.
The craft's camera spotted evidence of landslides on the slopes of craters. It also appears fine grains of rock and soil kicked up by impacts settled in low-lying areas as a sea of dust.
"These results from Dawn suggest Vesta's skin is constantly renewing," said Maria Cristina De Sanctis, head scientist for Dawn's visible and infrared mapping spectrometer at Italy's National Institute for Astrophysics in Rome.
Dawn's visible and infrared mapping spectrometer detected temperatures differentials on Vesta's surface from colder than minus 150 degrees Fahrenheit to minus 10 degrees Fahrenheit. The sharp temperature swings over small areas suggest Vesta's surface quickly responds to sunlight, according to NASA.
The probe also measured Vesta's global gravity field, which yields information on the asteroid's internal structure. Vesta's gravity model shows which regions of the asteroid are denser than others.