Dawn NASA’s Dawn Mission Journey to the Asteroid Frontier Lucy McFadden, Co-Investigator...

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

1

Dawn

DawnThe Dawn Mission

9th mission in NASA’s Discovery Program http://discovery.nasa.gov2

Dawn

DawnTraveling Back In Time

3

Dawn

Dawn

Dawn Explores the Earliest Epochs

Vesta and Ceres are intact survivors of the earliest epoch of planetary formation.

4

Dawn

Dawn

The Asteroid Belt

5

Dawn

Dawn

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

6

Dawn

Dawn

Interplanetary Trajectory

7

Dawn

Dawn

Ion Propulsion

Deep Space 1

8

Dawn

Dawn

Hydrazine tank

45 kg capacity

Xenon tank

450 kg capacity

Folded solar arraysIon thruster

2.3 meters

Ion Propulsion System

9

Dawn

Dawn

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

10

Dawn

DawnMap the Gravity Field

Vesta Gravity from Shape Model11

Dawn

Dawn

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

12

Dawn

Dawn

Mapping Global Topographic Maps

Framing Camera techniques have been proven on many previous missions. The camera’s most recent

heritage comes from Venus Express.

13

Dawn

Dawn

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

14

Dawn

Dawn

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

15

Dawn

Dawn

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

16

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.

17

Dawn

Dawn

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

18

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

19

Dawn

Dawn

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

20

Dawn

Dawn

2007 Vesta apparition

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

21

Dawn

Dawn

Hubble Space Telescope

22

Dawn

Dawn

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

23

Dawn

Dawn

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

24

Dawn

Dawn

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

25

Dawn

Dawn

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

26

Dawn

Dawn

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

27

Dawn

Dawn

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

Dawn

Dawn

500 km500 km

29

Dawn

Dawn

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

30

Dawn

Dawn

Ceres 2003, 2004

31

Dawn

Dawn

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)

32

Dawn

Dawn

Hubble images of Ceres reveal roundness, surface features, and colors

Three different faces of Ceres

33

Dawn

Dawn

Ceres’ Rotation

To see the video of Ceres’ rotation, go to:http://hubblesite.org/newscenter/archive/releases/2005/27/video/b/

34

Dawn

Dawn

35

Dawn

Dawn

Learn More!

http://dawn.jpl.nasa.gov

36

Dawn

Dawn

Unlocking the Mysteries

Science on the Edge of Our Solar System

3337