1 Nori Laslo Johns Hopkins University Applied Physics Laboratory A NASA Discovery Mission

2 Why Mercury? MESSENGER – a NASA Discovery Mission MESSENGER Mission Objectives Mission Challenges Mission Timeline MESSENGER Payload Mercury Dual Imaging System MESSENGER Load Building Process MESSENGER data

3 Why Mercury? Highest orbital eccentricity in the solar system Only planet with 3:2 spin orbit resonance Smallest axial tilt: 0.01 degrees Widest daily temperature range: 1100°F from day to night! (-300°F to 800°F) Highest uncompressed density in the solar system Largest ratio of core to size of planet: core is approximately 75% of Mercury’s radius, 42% of volume Most inclined orbit: 7 degrees off of the ecliptic Difficult to study with Earth-based telescopes: limited by proximity to Sun

4 Why Mercury? Some ground-based data: Arecibo, VLA, Goldstone Arecibo radar image of north polar deposits [Harmon et al., 2001].

5 Why Mercury? Mariner 10: First spacecraft to make use of “gravitational slingshot” Mapped 45% of planet’s surface Mariner 10 image of Discovery Rupes

6 MESSENGER: A NASA Discovery Mission NASA Discovery Program –Program began in 1994 –Goal is to launch low-cost, scientifically focused missions –Mission proposals, each led by a Principal Investigator, undergo rigorous scientific and technical reviews –MESSENGER is the seventh mission chosen by NASA Discovery Program

Near Earth Asteroid Rendezvous (NEAR) Mars Pathfinder Lunar Prospector Stardust Genesis Comet Nucleus Tour (CONTOUR) MESSENGER Deep Impact Dawn Kepler Deep Impact Mars Pathfinder StardustNEAR Lunar Prospector Genesis MESSENGER CONTOUR Dawn Kepler

9 Mission Objectives MESSENGER – MErcury Surface Space ENvironment GEochemistry and Ranging Six fundamental science questions to answer regarding the formation and evolution of Mercury (Solomon et al. 2001) 1.What planetary formational processes led to the planet’s high metal-to-silicate ratio? 2.What is Mercury’s geological history? 3.What are the nature and origin of Mercury’s magnetic field? 4.What are the structure and state of Mercury’s core? 5.What are the radar-reflective materials at Mercury’s poles? 6.What are the important volatile species and their sources and sinks on and near Mercury?

10 Mission Challenges: Mass Mass –Delta II 7925-H launch vehicle, largest available to a Discovery-class mission, limited total spacecraft mass to 1,107 kg –Much of the mass had to be fuel: 54% of total mass –Minimized dry mass: used lightweight titanium fuel tanks, carbon composite main structure, miniaturized instruments, integrated propulsion system into spacecraft structure –Minimized fuel required by selecting a complex trajectory utilizing gravity assists: maneuvers that use tug of a planet’s gravity to adjust speed or shape of spacecraft’s trajectory

11 Mission Timeline

12 Mission Timeline

13 Mission Timeline

14 Mission Timeline

15 Mission Timeline

16 Mission Timeline: Orbital Phase Orbit Insertion: March 18th, 2011 Requires ~33% of propellant One orbit = 12 hours Orbit is highly elliptical: periapsis altitude is 200km (124 mi), apoapsis altitude is 15,200 km (~9,420 mi) Solar gravity slowly changes spacecraft’s orbit; corrective maneuvers required every 88 days

17 Mission Challenges: Proximity to Sun At such a small distance, actually falling toward the Sun; increased spacecraft speed means we actually need to break for orbital insertion Solar radiation at Mercury 7-10 times that on Earth Key component of thermal design: unique ceramic-cloth sunshade to protect instruments from harsh solar environment Allowed for mostly standard electronics, components, and thermal blanketing materials

18 Thermal Design

20 Payload

21 Mercury Dual Imaging System

22 Mercury Dual Imaging System

23 Mercury Dual Imaging System

24 Mercury Dual Imaging System Narrow-Angle Camera (NAC): –1.5° Field of View –1024x1024 pixels –Focal length = 550mm – nm spectral range –Off-axis reflector:

25 Mercury Dual Imaging System Wide-Angle Camera (WAC): –10.5° Field of View –1024x1024 pixels –Focal length = 78 mm –Four-element refractor:

26 Mercury Dual Imaging System WAC also includes 12-color filter wheel; nm spectral range

Mercury Dual Imaging System

28 Load Building Process Instruments/ subsystems each build a sequence of commands All commanding is merged by payload manager; checked for conflicts Instruments/ subsystems each submit final sequence Mission Operations Team builds load and runs through simulator Simulator output is reviewed and errors fixed if necessary Load uplinked to spacecraft

29 MESSENGER Data The results are in.....

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 9, 2008 Distance: 1.7 million miles Narrow-Angle Camera Resolution: 70 km/pixel

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 13, 2008 Distance: 470,000 miles Narrow-Angle Camera Resolution: 20 km/pixel

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Distance: 17,000 miles Wide-Angle Camera Filter: 750 nm

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Distance: 3,600 miles Narrow-Angle Camera

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Distance: 21,000 miles Narrow-Angle Camera

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Distance: 3,600 miles Narrow-Angle Camera

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Narrow-Angle Camera

Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington January 14, 2008 Distance: 17,000 miles Wide-Angle Camera Filters: 1000, 700, 430 nm

38 For more information… Please visit: to see more data and animations (including the Earth and Venus flybys!), and for more information on the MESSENGER team and project. Questions? Nori at