Dawn

The Dawn mission will undertake a journey in both space and time by traveling to the two oldest and most massive space rocks in the asteroid belt between Mars and Jupiter, Vesta and Ceres. Their surfaces are believed to contain a snapshot of the conditions present in the solar system's first 10 million years, allowing Dawn to investigate both the origin and the current state of the solar system.

Vesta is a rocky body, while Ceres is believed to contain large quantities of ice. The profound differences in the geology of these two minor planets that formed and evolved in close proximity to each other form a bridge from the rocky bodies of the inner solar system to the icy bodies of the outer solar system. By observing asteroid Vesta and dwarf planet Ceres with the same set of instruments, Dawn has the unique ability to compare and contrast them and answer questions about the formation and evolution of the early solar system.

Mission Management		Dr. Christopher Russell Principal Investigator
The Dawn mission is managed for NASA by the Jet Propulsion Laboratory, Pasadena, CA. The Principal Investigator is Dr. Christopher Russell of the University of California at Los Angeles. Orbital Sciences Corporation, Dulles, VA, constructed the spacecraft, and JPL provided the ion engines.

Dawn's science goal is to characterize the conditions and processes in place at the beginning of solar system formation by investigating in detail two minor planets that followed very different evolutionary paths and have remained intact since their formation. Scientists hope to gain a new understanding of the role of size and water in planet evolution.

Dawn's science instruments will study Vesta and Ceres to:

The Dawn spacecraft launched from Cape Canaveral Air Force Station in Florida on September 27, 2007, aboard a Delta II rocket, beginning its 1.7 billion mile journey through the inner solar system. It is the first Discovery mission to be powered by ion propulsion, an advanced technology successfully demonstrated by NASA's Deep Space 1 mission. The use of solar electric ion thrusters enables Dawn to carry enough fuel and to adjust its velocity so it can orbit and study two planetary bodies on a single voyage -- the first spacecraft ever to do so.

In February 2009, Dawn got a gravity-assist from Mars, using the movement and gravity of Red Planet to alter its path, enlarging its elliptical orbit, and increasing its speed to save fuel, time and money. Dawn entered the asteroid belt to stay in November 2009, becoming the first human-made object to take up permanent residence in the rocky region between Mars and Jupiter.

Dawn entered into its year-long orbit around Vesta in July 2011, becoming the first spacecraft to orbit an object in the main asteroid belt. Dawn will orbit at different altitudes during its time at Vesta, beginning with a 1,700 mile survey orbit, then moving to a 420 mile High Altitude Mapping Orbit (HAMO), and then spiraling to a 110 mile Low Altitude Mapping Orbit (LAMO). After a return to HAMO for a few weeks, Dawn will cruise onward to dwarf planet Ceres to begin a four-month orbit in February 2015.

Vesta has a unique surface feature which scientists look forward to peering into. At the asteroid's south pole is a giant crater - 285 miles across and 8 miles deep. If Earth had a crater that was proportionately this large, it would fill the Pacific Ocean. The massive collision that created this crater less than one billion years ago gouged out one percent of the asteroid's volume, blasting over one-half million cubic miles of rock into space.

What happened to this tremendous amount of rock? The debris, ranging in size from sand and gravel to boulder and mountain, was ejected into space where it began its own journey through the solar system. Scientists believe that about 5 percent of all meteorites found on Earth are a result of this single ancient crash in deep space.

The meteorite pictured is a piece of crust from Vesta. Asteroid Vesta joins Mars and the Moon as the only three known solar system bodies that Earth scientists have cataloged samples from.