1/30/20081 messenger first mercury flyby first mercury flyby january 14, 2008 speaker: marilyn...
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1/30/2008 1MESSENGER First Mercury Flyby
First Mercury Flyby
January 14, 2008
Speaker: Marilyn Lindstrom Program Scientist, NASA Headquarters
NASA Museum Alliance Embargoed until 1 pm 1/30/08
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Mercury the Mystery Planet
• Least known terrestrial planet
• Mariner 10 only spacecraft– 3 flybys 1974-1975– Imaged just 45% of planet
– Large core– Small magnetic field
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MESSENGER the Mercury Orbiter
• Principal Investigator: Sean Solomon, Carnegie Institution of Washington (CIW)
• Project Manager: Peter Bedini Johns Hopkins University Applied Physics Laboratory (APL)
• Mission design, spacecraft development, and operations - APL
• Instruments provided by APL, NASA GSFC, U. Colorado, U. Michigan
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Science Questions
• Why is Mercury so dense?
• What is the geologic history of Mercury?
• What is the nature of Mercury’s magnetic field?
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Science Questions
• What is the structure of Mercury’s core?
• What are the unusual materials at Mercury’s poles?
• What volatiles are important at Mercury?
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Science Instruments
MDIS - dual imaging spectrometer, MASCS - UV-VIS-IR spectrometer, MLA - laser altimeter, MAG - magnetometerEPPS - energetic particles & plasma spectrometer, GRNS – gamma ray & neutron spectrometer, XRS - X-ray spectrometer
radio science uses Doppler on communications tracking
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Spacecraft
•Lightweight body•Large fuel tank (half the mass is fuel)•Several types of thrusters (bipropellant & hydrazine)•Ceramic fabric sunshade•Adjustable solar panels•Redundant systems (PSE,DPU)
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Trajectory
6 planetary flybys provide gravity assists to get into Mercury orbit (1 Earth, 2 Venus, 3 Mercury) We are about half-way there.
5 major propulsive maneuvers (and many minor ones) provide the thrust and guidance.
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Launch
Launched August 3, 2004 aboard a three-stage Boeing Delta II rocket!
1/30/2008 10MESSENGER First Mercury Flyby
Flyby Plan
Messenger approached in nightime on the Mariner 10 side and departed in daytime on the newly seen MESSENGER side.
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First Image Unseen Side
First Look on Jan. 14, 2008 at Mercury’s Previously Unseen Side
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Geology - Craters
Most crater ejects is closer to the rim than on the moon due to higher gravity.
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Geology – Scarps
Scarps (cliffs) can be hundreds of Km long; the scarp in this image is 200 Km (125 miles) wide.
Scarp
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Geology - Poles
North pole South pole
The south pole is more heavily cratered than the north pole.
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Geochemistry
The Mercury spectrum shows the degree to which different wavelengths of sunlight are absorbed or reflected by its surface materials. Dips in the spectrum indicate where sunlight shining on the surface is partially absorbed.
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Geophysics
•Laser Altimetry (MLA)
•Two craters are easily visible
•Magnetic Field•Internal, dipolar
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Magnetosphere
This plot shows the measured magnitude of the magnetic field of Mercury as MESSENGER executed its first flyby of that planet.
MESSENGER’s Magnetometer (MAG) provided definitive identification of all boundaries of the Mercury magnetosphere system and revealed a less active system than was seen during the first Mariner 10 flyby.
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Atmosphere
The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) found Sodium and Hydrogen tails that extend out 15,000 miles.
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Caloris Basin
Caloris basin is bigger and more complex than we thought: Mariner 10 saw less than ¼ of this basin that is one of the largest in the solar system. The estimated diameter has increased to 1550 km.
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Caloris Basin
Craters inside the basin include bright ray craters, a multi-ring basin, bright floored craters and dark halo craters. The surface on the interior is lighter color than that on the outside, indicating a difference in composition.
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Spider Radial Grabens
Radial graben “Spider” near center of Caloris basin is unique on Mercury, unseen on Moon or Mars