You are invited to read our new feature, the Dawn Journal, on the Outreach page. This occasional piece will log the progress of the Dawn mission during the race to the launch pad and through the journey to Vesta and Ceres. Log number 30 was added on 24 August, 2008.

Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail two of the largest protoplanets remaining intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Each has followed a very different evolutionary path constrained by the diversity of processes that operated during the first few million years of solar system evolution.

Those who are interested in following the developments of the mission may wish to subscribe to one of the mission's newsletters, the Education and Public Outreach Newsletter or the Science team newsletter, Dawn's Early Light. Information on subscriptions can be obtained by clicking on the respective links. In addition to the website that is maintained by the science team there is a more extensive website under development by the Education and Public Outreach team. On this website we concentrate on the history and rationale for the mission. Material on the mission, its science, the spacecraft, operations, outreach, background, news, and images can be accessed by clicking on the appropriate heading at the top of this page.

Dawn has much to offer the general public. It brings images of varied landscapes on previously unseen worlds to the public including mountains, canyons, craters, lava flows, polar caps and, possibly ancient lakebeds, streambeds and gullies. Students can follow the mission over an entire K-12 experience as the mission is built, cruises to Vesta and Ceres and returns data. The public will be able to participate through the Solar System Ambassadors and through participation on the web.

The top level question that the mission addresses is the role of size and water in determining the evolution of the planets. Ceres and Vesta are the right two bodies with which to address this question, as they are the most massive of the protoplanets, baby planets whose growth was interrupted by the formation of Jupiter. Ceres is very primitive and wet while Vesta is evolved and dry. The instrumentation to be flown is complete, flight-

Dawn Spacecraft

proven and similar to that used for Mercury, Mars, the Moon, Eros and comets. The science team consists of leading experts in the investigation of the rocky and icy planets using proven measurement and analysis techniques.

Dawn has the potential for making many paradigm-shifting discoveries. Ceres may have active hydrological processes leading to seasonal polar caps of water frost, altering our understanding of the interior of these bodies. Ceres may have a thin, permanent atmosphere distinguishing it from the other minor planets.

The three principal scientific drivers for the mission are first that it captures the earliest moments in the origin of the solar system enabling us to understand the conditions under which these objects formed. Second, Dawn determines the nature of the building blocks from which the terrestrial planets formed, improving our understanding of this formation. Finally, it contrasts the formation and evolution of two small planets that followed very different evolutionary paths so that we understand what controls that evolution.

This mission is very timely. Its journey in time to understand the conditions at the formation of the solar system provides context for the understanding of the observation of extra solar-planetary systems. It provides data on the role of size and water in planetary evolution and forms a bridge between the exploration of the rocky inner solar system and the icy outer solar system. Finally, it completes the first order exploration of the inner solar system, addresses NASA's goal of understanding the origin and evolution of the solar system and complements ongoing investigations of Mercury, Earth and Mars.

To view the paper on the Dawn mission presented at the 2002 Asteroids, Comets and Meteors conference, click here.(pdf file)

When Dawn was confirmed to go into development in February 2004 the Laser Altimeter and Magnetometer were not included. More recent descriptions of the mission can be found in papers presented at the IAA and IAC meetings in October 2005, and also the Acta Astronautica paper published in April 2006.. After these presentations the project was stood down for a period of review before continuation. On March 2, 2006 without warning the project was suddenly cancelled. JPL appealed this decision and on March 23 a review was held under the auspices of the NASA Administrator. On March 27, 2006 NASA announced that the appeal had been successful and Dawn would go forward to launch. A new launch date was then set for June 2007. Because of weather conditions both in Florida and the mid Atlantic, this launch opportunity proved to be impossible to use and Dawn was launched at the next and last available launch period, successfully being put into orbit on September 27, 2007.



Dawn title art background is from a painting by William K. Hartmann titled "A cocoon nebula, perhaps the primordial solar nebula."

Mission | Science | Spacecraft | Operations | Outreach | Background | News | Images | Home | EPO Website

For more information contact C. T. Russell, ctrussell@igpp.ucla.edu.

Last updated August 27,2008.