1. Ceres, Vesta, and comet 67p LIN TU

2. Outline Dawn Mission Ceres & Vesta Exospheric & Thermal Model 67p & Rosseta Mission 3. Dawn Mission 4. Dawn Mission Vesta Launch : 9. 27, 2007 Vesta arrival (initial orbit) 7. 16, 2011 Vesta lowest orbit Vesta departure 12. 13, 2011 Ceres Arrival : c. February 2015 5. Vesta & Ceres 6. Exosphere 7. The mechanisms of exosphere production 8. Herschel detected water vapor on Ceres. Ceres exosphere Kppers et al., 2014 Largest main belt asteroid Wet Escape velocity ~ 0.52 km/s Thermal velocity ~ 0.48km/s by 200K 9. Exospheric model Monte Carlo Method Ballistic motion Maxwellian distribution Sticking effect (T