Mercury: Mariner to MESSENGER and beyond

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Mercury Mariner to MESSENGER and beyond

• Dr. Ann L. Sprague
• Lunar and Planetary Laboratory
• The University of Arizona
• Participating Scientist MESSENGER Mission to
  Mercury

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Fleet footed MESSENGERWinged MESSENGER
RCA Building Façade, New York City, NY
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Mercury closest planet to the Sun and most
elliptical orbit
0.31 to 0.43 AU
e 0.21
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Image courtesy of our own Rik Hill
What does Mercury look like in the sky from your
backyard in Tucson?
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Mercury, marked with white line, visible at
sunrise from Tucson. Image courtesy of our own
Bob McMillan.
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This is a tough one Mercury spins three times
for every two revolutions about the Sun It has
same two longitudes (one or the other) under
the Sun at perihelion. This makes for
crazy temperatures on the surface!
Caused by gravitational interaction
between lemon shaped planetary figure and the
Sun
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Greatest temperature extremes of any planet in
our solar system
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Mitchell and de Pater (1997) Microwave
observations of Mercury,
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2 spacecraft to Mercury

1. Mariner 10
2. MESSENGER

Too fast
Slow Down
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Mariner 10 incoming Imagery mosaic 2 filters
in the ultra violet and 1 yellow filter 300 nm
(0.3 µm) to 400 nm (0.4 µm) and yellow to 550
nm (0.55 µm )
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Mariner 10 Out going Imagery
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Mariner 10 imaged less than half of Mercurys
surface
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How Mercury compares to its magnetic field
How Earth compares to its magnetic field
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It is thought that there must be a molten layer
of the planetary core to generate a magnetic
Field (like that at Earth) Ground-based observa
tions have found evidence for this by
measuring wobbles in Mercurys Motions.
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How the cores of the terrestrial planets compare
to the thickness of their rocky layers
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Discovery Scarp discovered by Mariner 10 imaging
Global shrinkage
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How scarps are formed
all three of these types of faults are found on
Mercury
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Atmospheric Discoveriesby poly chronometer on
Mariner 10our own Lyle Broadfoot, PI(my first
mentor at LPL)

• Hydrogen (H)
• Helium (He)
• Oxygen (O) upper limit and detection ??

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Ground-Based Observations

• 1976 to present
• Not much until new technology in telescopes and
  instruments
• Sensitive detectors
• Computer data analysis
• Relatively inexpensive telescopes and imaging
  systems for amateur astronomers

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For exosphere no collisions between
atoms collisions with surface
Keck I and Keck II on Mauna Kea
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For spectroscopic measurements of Mercurys
surface 13,895 ft ( 4630 m) altitude
NASA Infrared telescope on Mauna Kea
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Surface composition measurements using the Mid
infrared spectral region (4 14
micrometers) Compare to Ultra violet 0.1 to
.4 micrometers Visible .4 to .7
micrometers Near Infrared .7 to 3 micrometers
1 micrometer 1.0-6 m 1µm
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Ground based imagery by talented amateur
astronomers
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From Palomar Telescope with rapid imaging and
co-adding and registration (allignment)
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Ground based radar reflectivity imaging
Bright red is high Radar reflectivity
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Atmospheric Measurements

• Sodium (Na)
• Potassium (K)

Kitt Peak McMath Pierce Telescope
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MESSENGER NASA DISCOVERY MISSION
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1st MESSENGER Fly by of Mercury January 14, 2008

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MESSENGER out bound image, true color
Credit, APL MESSENGER
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Credit, APL MESSENGER
Caloris Basin on one of the hot longitudes
centered 30 degrees N
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Very bright light colored material in
craters In Caloris Basin
Credit APL MESSENGER
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Also dark rimmed craters
Credit APL MESSENGER
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The Spider in Caloris Basin
Credit, APL MESSENGER
Rising magma, uplift, volcanism
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Atmosphere measurements will be made by MASCS
throughout the mission

• Hydrogen (H)
• Sodium (Na)
• Calcium (Ca)
• Potassium (K)
• Magnesium (Mg) ?
• Oxygen (O) ?
• Sulfur (S) ?
• Silicon (Si) ?
• Others??

The Fast Ion Partical detector (FIPS) has
already discovered many unexpected ions in
Mercurys near environment
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Mercurys Na tail Streaming 40,000 km in the
anti-Sun direction
Radiation pressure Sunlight pressure
Ground-based with relatively simple Instrumentati
on Boston University group
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Ground-based from Kitt Peak McMath
Pierce Telescope Potter et al. 2006
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Mercurys neutral sodium atmospheric tail
Credit, APL MESSENGER
MESSENGER MASCS instrument during 1st fly by
January 14, 2008
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Surface Spectroscopy Mercury Atmospheric and
Surface Composition Spectrograph (MASCS)

• Measures light reflecting from the surface
• Measures wavelengths from 400 nm to 1400 nm
• visible (400 to 700 nm)
• near-infrared (700 to 1400 nm)

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Surface Spectroscopy with MASCS UV, VIS, NIR 250
nm to 1400 nm 0.25 µm to 1.4 µm
Credit APL MESSENGER
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A lot of new tectonic features seen in ery high
resolution images 200 m per pixel
Credit APL MESSENGER
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2 more fly bys October 6, 2008 September 29,
2009 Orbit insertion March 18,
2011 http//messenger.jhuapl.edu/soc/index.html
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European Space Agency (ESA) and Japan
(JAXA) Bepi Colombo Mission to Mercury Launch
2012