NASA's Dawn Spacecraft Enters Orbit Around Asteroid Vesta

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
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Priscilla Vega 818-354-1357
Jet Propulsion Laboratory, Pasadena, Calif.
priscilla.r.vega@jpl.nasa.gov

Dwayne C. Brown 202-358-1726
NASA Headquarters, Washington July 16, 2011
dwayne.c.brown@nasa.gov

News release: 2011-212

NASA's Dawn Spacecraft Enters Orbit Around Asteroid Vesta

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-212&cid=release_2011-212

PASADENA, Calif. -- NASA's Dawn spacecraft on Saturday became the first probe ever to enter
orbit around an object in the main asteroid belt between Mars and Jupiter.

Dawn will study the asteroid, named Vesta, for a year before departing for a second destination, a dwarf
planet named Ceres, in July 2012. Observations will provide unprecedented data to help scientists
understand the earliest chapter of our solar system. The data also will help pave the way for future human
space missions.

"Today, we celebrate an incredible exploration milestone as a spacecraft enters orbit around an object in the
main asteroid belt for the first time," NASA Administrator Charles Bolden said. "Dawn's study of the
asteroid Vesta marks a major scientific accomplishment and also points the way to the future destinations
where people will travel in the coming years. President Obama has directed NASA to send astronauts to an
asteroid by 2025, and Dawn is gathering crucial data that will inform that mission."

The spacecraft relayed information to confirm it entered Vesta's orbit, but the precise time this milestone
occurred is unknown at this time. The time of Dawn's capture depended on Vesta's mass and gravity, which
only has been estimated until now. The asteroid's mass determines the strength of its gravitational pull. If
Vesta is more massive, its gravity is stronger, meaning it pulled Dawn into orbit sooner. If the asteroid is less
massive, its gravity is weaker and it would have taken the spacecraft longer to achieve orbit. With Dawn
now in orbit, the science team can take more accurate measurements of Vesta's gravity and gather more
accurate timeline information.

Dawn, which launched in September 2007, is on track to become the first spacecraft to orbit two solar
system destinations beyond Earth. The mission to Vesta and Ceres is managed by NASA's Jet Propulsion
Laboratory in Pasadena, Calif., for the agency's Science Mission Directorate in Washington. Dawn is a
project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center
in Huntsville, Ala.

The University of California, Los Angeles, is responsible for the overall Dawn mission science. Orbital
Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max
Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical
Institute are part of the mission's team.JPL is a division of the California Institute of Technology in Pasadena.

For information about the Dawn mission, visit: http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov/ .

To follow the mission on Twitter, visit: http://www.twitter.com/NASA_Dawn . -end-

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