NASA's Dawn spacecraft, illustrated in this artist's concept, is propelled by ion engines. Image credit: NASA/JPL

PASADENA, Calif. -- NASA will host a news briefing at 11 a.m. PDT (2 p.m. EDT) on Thursday, June 23, to discuss the Dawn spacecraft's year-long visit to the large asteroid Vesta. The mission is expected to go into orbit around Vesta on July 16 and begin gathering science data in early August.

The event will be held at NASA Headquarters in Washington and will be broadcast live on NASA Television and streamed at http://www.nasa.gov/ntv . In addition, the event will be carried live on Ustream, with a live chat available, at http://www.ustream.tv/nasajpl2 .

Dawn's visit to Vesta will be the first prolonged encounter with a main belt asteroid and the first trip to a protoplanet, a large body that almost became a planet. Observations will help us understand the earliest chapter of our solar system's history.

See the website for more details. http://www.nasa.gov/mission_pages/dawn/news/dawn20110620.html （SY）