Posted on 07/03/2008 6:26:32 PM PDT by buccaneer81
First surprise from mission to Mercury: signs of water Thursday, July 3, 2008 8:43 PM By Kevin Mayhood THE COLUMBUS DISPATCH Mercury facts
Diameter: 3,032 miles
Magnetic field: only rocky planet other than Earth with an active magnetic field
Density: densest planet in solar system; 5.3 times denser than water
Distance from sun: average of 36 million miles
Distance from Earth: 50 million to 200 million miles Messenger facts
Distance Messenger will travel: 4.9 billion miles as the spacecraft circles the sun 14 times before slowing enough to enter Mercury's orbit
Size: 56 inches tall, 73 inches wide and 50 inches deep. Its sunshield is 8-foot by 6-foot and holds two, 20-foot solar panels
Weight: 1,120 pounds plus 2,411 pounds of rocket propellant
Instruments: include wide and narrow image cameras; gamma ray and neutron spectrometer; X-ray spectrometer; energetic particle and plasma spectrometer; atmospheric and surface composition spectrometer; laser altimeter; magnetometer
Last spacecraft sent to explore Mercury: Mariner 10 flew by in 1974 and 1975.
Source: NASA Water is escaping from Mercury's surface, which is pocked with ancient volcanoes and huge impact craters.
NASA got its most detailed look ever at the planet when its Messenger spacecraft traveled 14,000 miles along the equator during a recent 10-minute flyby.
Scientists reported their findings yesterday in 11 papers published in a special section of the journal Nature.
Messenger — short for the Mercury Surface, Space Environment, Geochemistry and Ranging mission — blasted off Aug. 3, 2004. The goal of the $446 million mission is to learn how Mercury has evolved.
The last NASA mission to the planet was during the mid-1970s.
"Mercury is the least understood terrestrial planet," said Steven A. Hauck, a geology professor at Case Western Reserve University and a Messenger scientist.
The planet speeds around the sun in 88 days, yet turns so slowly that sunset to sunset lasts 176 days. The sunny side can reach 800 degrees Fahrenheit and the dark side 300 below.
Mercury is the smallest and densest rocky planet in our solar system and might be 60 percent iron — twice that of Earth's makeup — NASA says. New readings show the surface is iron-poor, indicating a core thick with the metal.
George Gloeckler, a research scientist at the University of Michigan who is studying particles from the surface and thin atmosphere, said the flyby "was so fast, we weren't sure we'd see anything."
But about a dozen elements and compounds, including potassium, carbon, calcium and sulfur, were detected.
The most surprising?
"We found water-group molecules. Where do they come from?" Gloeckler said.
There are a few theories. Hydrogen spewed from the sun might strike oxygen on the surface of Mercury and form water, said Thomas Zurbuchen, a professor of aerospace engineering and space science at the University of Michigan.
Or asteroids that struck the surface in the past might have brought water to the planet.
The scientists found highly charged forms of elements and compounds not seen elsewhere in the solar system. Zurbuchen said Mercury's magnetic field might accelerate electrons within the field that collide with ions from the planet, knocking off an electron or two and increasing the charge.
New photographs show volcanoes and asteroid strikes that formed much of the surface. They also reveal deep cracks that are created as the planet cools and contracts.
The last images of Mercury were made by the Mariner 10 flybys in 1974 and 1975.
"The surface appears to be very old — older than the Earth's," said Hauck, who is studying the planet's topography.
Messenger is scheduled to fly past Mercury on Oct. 6 and again on Sept. 29 next year, then enter Mercury's orbit on March 18, 2011.
"Hopefully, everything will continue to keep working," Gloeckler said. "We will see how things change with time and under different solar conditions and hopefully be able to solve many of the puzzles of the planet."
Ping!
How does Mercury come to have a magnetic field without an atmosphere?
It has an iron core, which produces its magnetic field.
I have heard that old yarn. It doesn’t add up. Some physicist was asked a century ago what produces earth’s mag field and he said, iron core and nobody has thought to investigate what is actually going on. Everybody just accepted the nursery tale and away we go.
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