Feature/Overview
and Objectives
Dawn Dictionary
Why Ceres and Vesta?
Technology
Orbit Visualization Tools:
Ceres
Vesta
Archive

Podcasts from 2007 Dawn Launch Educator Conference
+ Cratering Lecture
+ 'What Makes a Planet?'    Lecture

Image of Vesta Credit: Hubble SpaceTelescope

Hubble Images of Asteroids Help Astronomers Prepare for Spacecraft Visit

To prepare for the Dawn spacecraft’s visit to Vesta, astronomers used Hubble’s Wide Field Planetary Camera 2 to snap new images of the asteroid. The image at left was taken on May 14 and 16, 2007. Using Hubble, astronomers mapped Vesta’s southern hemisphere, a region dominated by a giant impact crater formed by a collision billions of years ago. The crater is 285 miles (456 kilometers) across, which is nearly equal to Vesta's 330-mile (530-kilometer) diameter. If Earth had a crater of proportional size, it would fill the Pacific Ocean basin. The impact broke off chunks of rock, producing more than 50 smaller asteroids that astronomers have nicknamed “vestoids.” The collision also may have blasted through Vesta’s crust. Vesta is about the size of Arizona.
+ Read more
+ See Vesta Gallery

Overview

Dawn's goal is to achieve an understanding of the conditions and processes acting at the solar system's earliest epoch. Dawn investigates the internal structure, density and homogeneity of two complementary protoplanets, 1 Ceres and 4 Vesta, that have remained intact since their formation, by measuring their mass, shape, volume and spin rate with both imagery, laser altimetry and gravity. Dawn records the protoplanets' elemental and mineral composition to determine their thermal history and evolution and provides context for meteorites (asteroid samples already in hand). Dawn images Ceres and Vesta's surfaces to determine their bombardment and tectonic history, uses gravity and spin state to limit the size of any metallic core, and infrared and gamma ray spectrometry to search for water-bearing minerals.

Measurements Objectives:

• Internal structure, density and homogeneity of two complementary protoplanets,
  1 Ceres and 4 Vesta, one wet and one dry
• Determine shape, size, composition and mass
• Surface morphology, cratering
• Determine thermal history and size of core
• Understand role of water in controlling asteroid evolution
• Test the current paradigm of Vesta as the howardite, eucrite, and diogenite (HED) parent body and determine which, if any, meteorites come from Ceres
• Provide a geologic context for HEDs

+ See archived Science features

Dawn's Early Light

The Science team newsletter, Dawn's Early Light, has been established to keep members of the scientific community informed about the Dawn mission. Current and past issues are available on line.

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