NASA's Dawn Mission: Exploring Vesta and Ceres in the Asteroid Belt

1. NASA’s Dawn MissionJourney to the Asteroid Frontier Lucy McFadden, Co-Investigator University of Maryland College Park, MD July 30, 2007 Planetary Science Workshop, Montevideo, Uruguay

2. The Dawn Mission 9th mission in NASA’s Discovery Program Discovery.nasa.gov

3. Traveling Back In Time

4. Dawn Explores the Earliest Epochs Vesta and Ceres are intact survivors of the earliest epoch of planetary formation.

5. The Asteroid Belt

6. Spacecraft Dry mass: 745 kg Wet mass: 1240 kg Solar array power (1 AU): 10.3 kW Solar array power (3 AU): 1.3 kW Delta II 7925H-9.5

7. Interplanetary Trajectory

8. Ion Propulsion Deep Space 1

9. Ion Propulsion System 2.3 meters Hydrazine tank 45 kg capacity Xenon tank 450 kg capacity Ion thruster Folded solar arrays

10. Instruments HGA – High Gain Antenna LGA – Low Gain AntennaCSS – Coarse Sun Sensors GRaND – Gamma Ray and Neutron Detector IPS Thrusters – Ion Propulsion ThrustersRCS Thrusters – Reaction Control System ThrustersVIR – Visual and Infrared Spectrometers FC – Framing Camera

11. Map the Gravity Field Vesta Gravity from Shape Model

12. Framing Camera FC current design (left) FC EM (below) Supports: Imaging Science Navigation Topography Gravity ScienceThese functions are mission critical Two identical units to fly for 100% redundancy • 1024 x 1024 pixels • frame-transfer CCD • 14 µm pixel size • F/8 system • 5.5° x 5.5° FoV • 93 µrad iFoV (1 pixel) • 7 filters + clear channel

13. Mapping Global Topographic Maps Framing Camera techniques have been proven on many previous missions. The camera’s most recent heritage comes from Venus Express.

14. Mapping Spectrometer: VIR • VIR experiment is a compact imaging spectrometer housing two data channels in the same optical head . It is made of 2 modules • Optical head • Electronics box VIR will allow to perform spectroscopic measurements of the Vesta and Ceres surface in the range 0.35-5.01 um were most signatures of rock-forming minerals are present

15. GRaND Cutaway view of GRaND • Features • Neutron spectroscopy using Li-loaded glass and boron-loaded plastic phoswich • Gamma ray spectroscopy using Bismuth Germanate and Cadmium Zinc Telluride (new technology) • Design enables measurement and suppression of background from the space environment • Operating modes • Standby • Operating • Anneal 25.7 cm 18.0 cm

16. Map the Elemental Composition Gamma ray and neutron detector (GRaND) techniques have been proven on Lunar Prospector. GRaND’s most recent heritage is from Mars Odyssey

17. Exploring New Worlds • Dawn’s Itinerary: • Launch September, 2007 • The Dawn Spacecraft will travel • 6.3 billion kilometers (almost 4 billion miles) • In almost ten years • To the asteroids, 4 Vesta and 1 Ceres.

18. Hubble WFPC2 Vesta May 2007 Color Composite http://hubblesite.org/newscenter/archive/releases/2007/27

19. Ceres’ Rotation http://hubblesite.org/newscenter/archive/releases/2005/27/

20. Learn More! http://dawn.jpl.nasa.gov

21. Partners • University of California, Los Angeles • Scientific Leadership • JPL – Jet Propulsion Laboratory • Management and Navigation • Orbital Sciences Corporation • Spacecraft design and build • Los Alamos National Laboratory • GRAND instrument • DLR – German Aerospace Center • Framing Camera • Max Planck Institute for Solar System Research • Framing Camera • ASI – Italian Space Agency • VIR • New Roads School, University of Maryland, and McREL • Education and Public Outreach

22. Mission Timeline Baseline mission shown in green Minimum mission shown in blue (1) Ceres arrival (4) Vesta departure (4) Vesta arrival Mars gravity assist End of mission Aug ‘15 May ‘12 (1) Ceres arrival (4) Vesta departure Mar ‘09 Jan‘16 Oct ‘11 Launch Sep ‘15 Feb ‘12 Jun ‘07 Note: There is a continuum of options between the baseline and minimum, varying in scientific return, cost, and technical robustness.

23. Background of Ceres First asteroid discovered in 1801 Biggest asteroid with a diameter about 1000 km a=2.77 AU, e=0.079, i=10.6 Probably hydrated (Lebofsky 1981, Feierberg 1981) or ammoniated (King et al. 1992) Target of Dawn, scheduled to orbit Ceres in 2015 for 11 months

24. 2007 Vesta apparition • Vesta last made such a close approach to Earth in June, 1989.

25. Hubble Space Telescope

26. Vesta in May 2007 • Wide Field Planetary Camera 2 (WFPC2) • Four Filters: F439W, F673N, F953N, F1042M • Same filters as previous observations in 1994, 1996. • Preliminary image deconvolution • Maximum Entropy Method (MEM) • Color composite images: F439W+F673N

27. Hubble WFPC2 F439W image of asteroid Vesta in May 2007: raw

28. Hubble WFPC2 F439W Vesta in May 2007: deconvolved (MEM)

29. Hubble WFPC2 F439W images of asteroid Vesta in May 2007: raw

30. Hubble WFPC2 F439W Vesta in May 2007: deconvolved (MEM)

31. 500 km 500 km

32. Ceres observations 2003-2004 • Map Ceres through one complete rotation in multiple filters. • Improve knowledge of its size, shape and pole orientation. • Search for satellites • Extend knowledge • Apply to sequence planning for Dawn

33. Ceres 2003, 2004

34. Hubble images of Ceres in January 2004 • Advanced Camera for Surveys (ACS) High Resolution Channel (HRC) • Filters: F220W, F330W, F555W • Sub-sampled (dithered) images were drizzled to enhance resolution • Color composite images: F330W+F555W • Movies made from lower-resolution images (full phase coverage)

35. Hubble images of Ceres reveal roundness, surface features, and colors Three different faces of Ceres

37. Unlocking the Mysteries Science on the Edge of Our Solar System