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The Planet Mercury
The elusive planet Mercury has defied scientific explanation and understanding due to its location near the sun. Mariner 10 in the 1970's took the first images of Mercury. Data from Mariner also suggested that Mercury has a magnetic field.
These findings gave NASA a reason to return to planet Mercury for further study of the Mariner 10 findings. Creating the Messenger mission satellite that began orbiting Mercury in March of 2011.
Mercury, like that of the Earth, is a magnetic dipole. A large part of its composition is Iron. Mercury was named for the messenger God in Greek Mythology. It also shares several elements not uncommon to Earth, such as, Calcium, Sodium, Sulpher, Magnesium, and Iron. It's Magnetic field is stronger than once thought and it does have a very thin exosphere that does, by chemical reaction, replenish itself through ionization. There is also evidence that this reaction is due to probable Ionized oxygen (O+) which could account for the regeneration of Mercurys exosphere.
In March 2011 NASA's Messenger went into orbit around the planet Mercury. The mission agenda was to answer six key questions about the planet.
1. Why is Mercury so dense?
2. What is the geologic history of Mercury?
3. What is the nature of Mercury's magnetic field?
4. What is the structure of Mercury's core?
5. What are the unusual reflective materials seen at Mercury's poles?
6. What volitiles are important at Mercury's exosphere?
Mercurys metal to rock ratio is higher than in any other planet in our solar system. Making it the densest planet as well as the smallest planet leading to scientific debate about its formation. Planetary impact has been suggested for why the core ratio is larger than the crust on Mercury.
NASA's measurements of Mercury's core density is 5.3g C3 which is higher than Earth's 4.0g. Mercury's core volume is @ 42% of the planets mass compared to Earths core volume of 16%. The gravity measurements on Mercury are the same as conditions on planet Mars.
Mercury does have a magnetic field like that of earth on a much smaller scale but strong enough to deflect the solar wind and plasma away from Mercurys surface much like that of the Earths magnetic field. The findings suggest that Mercurys core does have a liquid outer layer surrounding the solid iron core in able for the planet to generate a magnetic field. Evidence shows that Mercury has not cooled as previously thought but is still cooling and maintains an active core.
The answers to the nature of Mercurys magnetic field will have to wait for better understanding of Mercurys core.
Where the energy comes from to produce the active core is only speculation and is not yet fully understood. We know Mercury has an active liquid layer around its iron core we just can't explain why. Question #5 has a partial answer yet remains incomplete at this time. The real question is where does the energy to produce an active core come from. Accounting for the energy released in ionization of volitile elements is not enough to account for this energy. Further studies and tests will need to continue to find the answer.
Nearly two years on NASA's Messenger mission has discovered that "The high abundance of volitile elements, sulphur and potassium in Mercury's surface suggests that Mercury did not experience extreme heating during its formation and early evolution."
This finding was unexpected by leading planetary scientists studying Mercurys formation. The new findings suggest that Mercury must have formed in colder temperatures and not a heated environment in order to maintain these volitile elements in Mercurys surface. If a heating event had formed Mercury as we know it today there would be no volitile elements detected due to there low melting points. Sulpher and postassium would have evaporated from the surface in an extreme heating event during formation.
This finding seems to rule out the giant impact theory, the stripping away of the planets outer portion of Mercury's rocky outer mantle, and undo the idea that the planets outer portion could have been evaporated by an especially hot phase of the early sun. In conclusion, NASA scientists previous model of the formation of Mercury cannot be supported as previously thought. NASA has ruled against a high temperature origin for Mercury leaving question #2 open for further debate.
Another unexpected find was water ice present in the continuously shaded hollows at the poles of Mercury. This find was not expected due to Mercury's extreme hot and cold temperature fluxuation. Never the less, water ice has been confirmed at Mercury's poles. That answers question 5.
The volitile elements detected in Mercury's exoshpere are hydrogen, helium, oxygen, sodium, potassium, calcium, and magnesium. Which for now answers question #6.
The composition of planet Mercury collected from the Messenger satellite finds its chemical composition to be,
to be continued...