Hidden Territory on Mercury Revealed

SpaceWarper sent me an alert for the recent information about the MESSENGER spacecraft third flyby of Mercury.

I must admit that I have not been following the mission closely.
http://messenger.jhuapl.edu/index.php

My bad, as there are some interesting results and the spacecraft isn't even in orbit yet.
- LRK -
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http://science.nasa.gov/headlines/y2009/03nov_hiddenterritory.htm?list1335507
Hidden Territory on Mercury Revealed
11/03/2009

Nov. 3, 2009: The MESSENGER spacecraft's third flyby of the planet Mercury has given scientists, for the first time, an almost complete view of the planet's surface and revealed some dramatic changes in Mercury's comet-like tail.

"The new images remind us that Mercury continues to hold surprises," says Sean Solomon, principal investigator for the mission and director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington.

The probe flew by Mercury on Sept. 29th, executing a critical gravity assist maneuver designed to help MESSENGER enter Mercury-orbit in 2011. Despite shutting down temporarily because of a power system switchover during a solar eclipse, the spacecraft's cameras and instruments revealed 6 percent of the planet's surface never before seen at close range, including this picturesque region pocked by impact craters and molded by volcanic activity:
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IRON AND TITANIUM SURFACE

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http://www.csmonitor.com/2009/1104/p02s10-usgn.html
NASA's Messenger probe reveals new clues about Mercury

Mercury, the oddest of the rocky planets, has been little understood by scientists. But on a swing by the planet, NASA's Messenger sent back intriguing data about Mercury's surface minerals and volcanic activity.

NASA's Mercury mission spacecraft, Messenger, is revolutionizing humanity's view of the first rock from the sun. And its primary science mission hasn't even started yet.

During its third and final flyby of Mercury, NASA's Messenger has found minerals on the planet's surface that current models say shouldn't be there in such abundance. And it appears that the planet was volcanically active – explosively so – for far longer than current ideas about its geological history suggest.

The flyby took place Sept. 29. Mission scientists unveiled highlights from the flyby during a press briefing Tuesday afternoon.
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Many images and much information.
- LRK -

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http://messenger.jhuapl.edu/news_room/presscon_multi6.html
MESSENGER Teleconference Multimedia Page

Presenter #1
Sean Solomon, MESSENGER Principal Investigator, The Carnegie Institution of Washington, Washington, D.C.

A MESSENGER color observation of Mercury obtained as the spacecraft approached the planet for its third and final flyby on 29 September 2009. The 1000, 700, and 430 nm filters were combined in red, green, and blue to create this color image (approximately 5 km/pixel resolution), the last that will be acquired until MESSENGER goes into orbit around Mercury in March of 2011. Only 6% of Mercury's surface in this image had not been viewed previously by spacecraft, and most of the measurements made by MESSENGER's other instruments during this flyby were made prior to closest approach. The observations nonetheless revealed fresh surprises.

Presenter #2
Ronald J. Vervack, Jr., MESSENGER Participating Scientist, The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Illustration of the major source and loss processes that generate and maintain Mercury’s exosphere. The panels on the left summarize the three primary sources of exospheric material. Photon-stimulated desorption occurs when solar photons excite surface-bound atoms or molecules, releasing them to the exosphere. Sunlight also heats the surface, causing atoms and molecules to evaporate. These are both low-energy processes, so most of the released material reaches only low altitudes and usually returns to the surface. Ion sputtering occurs when ions from the solar wind or Mercury’s magnetosphere impact the surface, “knocking off” atoms and molecules. Meteoroid vaporization occurs when incoming meteoroids, generally small dust particles, impact Mercury’s surface at high speeds, causing the surface material to vaporize. Both ion sputtering and meteoroid vaporization are high-energy processes, and the released material can reach high altitudes. All material in the exosphere is accelerated in the anti-sunward direction by radiation pressure; atoms and molecules at sufficiently high altitudes for this force to overcome the gravitational influence of the planet enter Mercury’s neutral tail. Neutral constituents in the tail either escape the Mercury system or are ionized by solar radiation. The ionized material can also escape along open magnetic field lines, but some of the ions are returned to the surface by Mercury’s magnetosphere.
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Presenter #3
David J. Lawrence, MESSENGER Participating Scientist,
The Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

Schematic view of Mercury’s interior showing its large, iron-rich core, which constitutes at least ~60% of the planet’s mass.
Observations from Earth and by MESSENGER at visible and near-infrared wavelengths have shown that Mercury’s surface has a very low concentration of iron (Fe) in silicate minerals, leading to the common view that Mercury’s surface and crust are generally low in iron. A puzzle for investigations of Mercury’s formation and evolution is how a planet with such a large Fe-rich core could form with such an Fe-poor surface?
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Presenter #4
Brett Denevi, MESSENGER Imaging Team member and Postdoctoral Researcher, Arizona State University, Tempe, Ariz.

Combined image coverage map of Mercury after Mariner 10 and MESSENGER’s first two flybys of Mercury. Although 90% of Mercury’s surface had been imaged after MESSENGER’s second flyby, there was a gap in longitudinal coverage centered at about 60° E.

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[Note: your really want to go to the reference link to see all the images and information I left out. - LRK -]
http://messenger.jhuapl.edu/news_room/presscon_multi6.html

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Why Mercury - First Rock from the Sun.
- LRK -

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http://messenger.jhuapl.edu/why_mercury/index.html
Mercury: The Key to Terrestrial Planet Evolution

Mercury, Venus, Earth, and Mars are terrestrial (rocky) planets. Among these, Mercury is an extreme: the smallest, the densest (after correcting for self-compression), the one with the oldest surface, the one with the largest daily variations in surface temperature, and the least explored. Understanding this "end member" among the terrestrial planets is crucial to developing a better understanding of how the planets in our Solar System formed and evolved. To develop this understanding, the MESSENGER mission, spacecraft, and science instruments are focused on answering six key outstanding questions that will allow us to understand Mercury as a planet. For additional, detailed information about the driving science questions of the MESSENGER mission, check out some of the articles given on the MESSENGER publication list.
http://messenger.jhuapl.edu/the_mission/publications.html
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Read more about the mission.
- LRK -

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http://messenger.jhuapl.edu/the_mission/index.html
The Mission

To become the first spacecraft to orbit Mercury, MESSENGER must follow a path through the inner solar system, including one flyby of Earth, two flybys of Venus, and three flybys of Mercury. This impressive journey is returning the first new spacecraft data from Mercury since the Mariner 10 mission over 30 years ago. Here you can find details about that journey, the MESSENGER spacecraft, and the instrument payload.
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Thanks for looking up with me.

Larry Kellogg

Web Site: http://lkellogg.vttoth.com/LarryRussellKellogg/
BlogSpot: http://kelloggserialreports.blogspot.com/
Newsletter: https://news.altair.com/mailman/listinfo/lunar-update
Twitter: http://twitter.com/lrkellogg
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WHAT THE MIND CAN CONCEIVE, AND BELIEVE, IT WILL ACHIEVE - LRK

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