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The MESSENGER Mission to Mercury. Nori Laslo Johns Hopkins University Applied Physics Laboratory. A NASA Discovery Mission. Why Mercury? MESSENGER – a NASA Discovery Mission MESSENGER Mission Objectives Mission Challenges Mission Timeline MESSENGER Payload Mercury Dual Imaging System
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The MESSENGER Mission to Mercury Nori Laslo Johns Hopkins University Applied Physics Laboratory A NASA Discovery Mission
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
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
Why Mercury? • Some ground-based data: Arecibo, VLA, Goldstone Arecibo radar image of north polar deposits [Harmon et al., 2001].
Why Mercury? • Mariner 10: 1974-1975 • First spacecraft to make use of “gravitational slingshot” • Mapped 45% of planet’s surface Mariner 10 image of Discovery Rupes
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 Mars Pathfinder Lunar Prospector Genesis Stardust CONTOUR MESSENGER Deep Impact Dawn Kepler • Near Earth Asteroid Rendezvous (NEAR) • Mars Pathfinder • Lunar Prospector • Stardust • Genesis • Comet Nucleus Tour (CONTOUR) • MESSENGER • Deep Impact • Dawn • Kepler
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) • What planetary formational processes led to the planet’s high metal-to-silicate ratio? • What is Mercury’s geological history? • What are the nature and origin of Mercury’s magnetic field? • What are the structure and state of Mercury’s core? • What are the radar-reflective materials at Mercury’s poles? • What are the important volatile species and their sources and sinks on and near Mercury?
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
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
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
Mercury Dual Imaging System • Narrow-Angle Camera (NAC): • 1.5° Field of View • 1024x1024 pixels • Focal length = 550mm • 700-800 nm spectral range • Off-axis reflector:
Mercury Dual Imaging System • Wide-Angle Camera (WAC): • 10.5° Field of View • 1024x1024 pixels • Focal length = 78 mm • Four-element refractor:
Mercury Dual Imaging System • WAC also includes 12-color filter wheel; 395-1040 nm spectral range
MESSENGER Data The results are in.....
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 Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
For more information… • Please visit: http://messenger.jhuapl.edu to see more data and animations (including the Earth and Venus flybys!), and for more information on the MESSENGER team and project. Questions? Email Nori at nori.laslo@jhuapl.edu.