dawn nasa’s dawn mission journey to the asteroid frontier lucy mcfadden, co-investigator...
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Dawn
Dawn
NASA’s Dawn MissionJourney to the Asteroid Frontier
Lucy McFadden, Co-Investigator
University of Maryland
College Park, MD
July 18, 2007
Night Sky Network
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DawnThe Dawn Mission
9th mission in NASA’s Discovery Program http://discovery.nasa.gov2
Dawn
DawnTraveling Back In Time
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Dawn Explores the Earliest Epochs
Vesta and Ceres are intact survivors of the earliest epoch of planetary formation.
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The Asteroid Belt
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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
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Interplanetary Trajectory
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Ion Propulsion
Deep Space 1
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Hydrazine tank
45 kg capacity
Xenon tank
450 kg capacity
Folded solar arraysIon thruster
2.3 meters
Ion Propulsion System
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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
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DawnMap the Gravity Field
Vesta Gravity from Shape Model11
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Framing Camera
FC current design (left)FC EM (below)
Supports: Imaging Science Navigation Topography Gravity Science
These 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
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Mapping Global Topographic Maps
Framing Camera techniques have been proven on many previous missions. The camera’s most recent
heritage comes from Venus Express.
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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
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GRaND
25.7 cm18.0 cm
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
CBE UncertaintyMass (g) 10,100 900
Power (mW)Standby 1,400 420Operating 11,200 1,680Anneal 12,800 2,560
Data Rate (bps) 3,100 adjustable
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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
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Dawn
DawnExploring New Worlds
Dawn’s Itinerary: Launch September, 2007
The Dawn Spacecraft will travel
• 6.3 billion kilometers (almost 4 billion miles)
• In eight years
• To the asteroids, 4 Vesta and 1 Ceres.
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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
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Dawn
DawnMission Timeline
Launch
Jun ‘07
(1) Ceresarrival
Aug ‘15
(4) Vestaarrival
Oct ‘11
(4) Vestadeparture
May ‘12
Mars gravity assist
Mar ‘09
End of mission
Jan ‘16
(1) Ceresarrival
Sep ‘15
(4) Vestadeparture
Feb ‘12
Note: There is a continuum of options between the baseline and minimum, varying in scientific return, cost, and technical robustness.
Baseline mission shown in greenMinimum mission shown in blue
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Background of CeresBackground of Ceres
First asteroid discovered in 1801First asteroid discovered in 1801
Biggest asteroid with a diameter about 1000 kmBiggest asteroid with a diameter about 1000 km
aa=2.77 AU, =2.77 AU, ee=0.079, =0.079, ii=10.6=10.6
Probably hydrated (Lebofsky 1981, Feierberg 1981) or Probably hydrated (Lebofsky 1981, Feierberg 1981) or ammoniated (King et al. 1992)ammoniated (King et al. 1992)
Target of Dawn, scheduled to orbit Ceres in 2015 for 11 Target of Dawn, scheduled to orbit Ceres in 2015 for 11 monthsmonths
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2007 Vesta apparition
• Vesta last made such a close approach to Earth in June, 1989.
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Hubble Space Telescope
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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
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Hubble WFPC2 F439W image of asteroid Vesta in May 2007: raw
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Hubble WFPC2 F439W Vesta in May 2007: deconvolved (MEM)
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Hubble WFPC2 F439W images of asteroid Vesta in May 2007: raw
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Hubble WFPC2 F439W Vesta in May 2007: deconvolved (MEM)
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Hubble WFPC2 Vesta May 2007 Color Composite
To watch the Rotation of Vesta, click here:http://hubblesite.org/newscenter/archive/releases/2007/27/video/a/28
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500 km500 km
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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
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Ceres 2003, 2004
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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)
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Hubble images of Ceres reveal roundness, surface features, and colors
Three different faces of Ceres
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Ceres’ Rotation
To see the video of Ceres’ rotation, go to:http://hubblesite.org/newscenter/archive/releases/2005/27/video/b/
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Learn More!
http://dawn.jpl.nasa.gov
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Unlocking the Mysteries
Science on the Edge of Our Solar System
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