surface of mercury

amazed

Tuesday January 15, 2008
NASA probe zips above surface of planet Mercury
By Will Dunham


WASHINGTON (Reuters) - A car-sized NASA probe zoomed about 203 km above the rocky, crater-scarred surface of Mercury on Monday, becoming the first spacecraft since 1975 to fly past the closest planet to the sun.

The U.S. space agency's MESSENGER probe traveled at about 25,700 kph as it passed over Mercury on a mission designed to resolve some of the mysteries about the solar system's innermost planet, officials said.

An Indian school boy watches the planet Mercury passing by the sun. (REUTERS/Jayanta Shaw/Files)

"So far, things look pretty good. The spacecraft was on the course we wanted it to be on," Michael Paul, a mission engineer, said in a telephone interview.

It flew roughly along the equator and at a slightly higher altitude than originally planned, but the change had no negative effects, Paul said. He said the probe was briefly out of contact as it passed behind Mercury but communications were quickly re-established.




In addition to Monday's rendezvous, MESSENGER is scheduled to pass Mercury again this October and in September 2009, using the pull of the planet's gravity to guide it into position to begin a planned yearlong orbit of the planet in March 2011.

Mark Robinson of Arizona State University, a member of the mission's science team, said the closest approach was on the planet's "night side" -- the one facing away from the sun.

The probe is due on Tuesday to begin transmitting back to Earth data it collected during the fly-by, Paul said. NASA said it hopes to have the first scientific results available for the public later this month.

The probe's equipment is gathering data on the mineral and chemical composition of Mercury's surface, its magnetic field, its surface topography and its interactions with the solar wind, according to scientists working on the project.

By the time the mission is completed, scientists also hope to get answers on why Mercury is so dense, its geological history, the structure of its iron-rich core and other issues.

TEMPERATURE SWINGS

MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging. Launched in 2004, it already has flown past Venus twice and Earth once en route to Mercury.

"This was fantastic," Paul said. "We were closer to the surface of Mercury than the International Space Station is to the Earth."

The only previous times Mercury was visited by a spacecraft were in 1974 and 1975 when NASA's Mariner 10 flew past it three times and mapped about 45 percent of its surface.

With Pluto now considered a dwarf planet, Mercury is the solar system's smallest planet, with a diameter of 4,880 km, about a third that of Earth.

Robinson said the probe's seven scientific instruments were turned on, although some may not be fully utilized until it goes into orbit three years from now.

A surface feature of great interest to scientists is the Caloris basin, an impact crater about 1,300 km in diameter, one of the biggest such craters in our solar system. It likely was caused when an asteroid hit the planet long ago.

By studying material in the crater, scientists hope to learn about the subsurface of the planet.

Mercury experiences the largest swing in surface temperatures in our solar system. When its surface faces the sun, temperatures hit about 800 degrees Fahrenheit, but when its faces away from the sun they can plummet to minus-300 Fahrenheit .




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naen

NASA Probe Shows Mercury More Dynamic Than Thought
October 29, 2008 (AP)

Earth's first nearly full look at Mercury reveals that the tiny lifeless planet took a far greater role in shaping itself than was thought, with volcanoes spewing "mysterious dark blue material."

New images from NASA's Messenger space probe should help settle a decades-old debate about what caused parts of Mercury to be somewhat smoother than it should be. NASA released photos Wednesday, from Messenger's fly-by earlier this month, that gave the answer: Lots of volcanic activity, far more than signs from an earlier probe.

Astronomers used to dismiss Mercury, the planet closest to the sun, as mere "dead rock," little more than a target for cosmic collisions that shaped it, said MIT planetary scientist Maria Zuber.

"Now, it's looking a lot more interesting," said Zuber, who has experiments on the Messenger probe. "It's an awful lot of volcanic material."

New images of filled-in craters

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After the Messenger made the closest approach ever to Mercury, skimming just 124 miles above the surface, the Mercury Dual Imaging System (MDIS) captured some of of the highest-resolution color images ever obtained of the planet. The MDIS uses 11 narrow-band spectral filters covering visible and near-infrared wavelengths. The specific colors of the filters help discriminate among the common minerals. Using a combination of three images, Mercury, as might be seen by the human eye, left, shows only slight color differences. However, Mercury's color image, right, using methods with 11 filters, reveals exaggerated color trends.


By taking pictures in a focused range of 11 color bands, the Messenger is able to capture enhanced color differences on Mercury's surface, providing insight into the composition and the geologic processes that caused these color differences. The bright orange material (left arrow) just below the Lermontov crater is most likely the after-effect of many volcanic eruptions in Mercury's violent past. The wispy blue linear fragments are rays of distant impact craters, while the mysterious dark-blue features unevenly covering Mercury's surface seem to be highly concentrated in a small area (right arrow). The previous slide is a close-up image of the region in the white box.


This wide-angle camera image was acquired nine minutes and 14 seconds after the Messenger's closest approach to Mercury on its second flyby, when the spacecraft was moving at 3.8 miles per second. This portion of Mercury's surface was previously imaged under different lighting conditions by Mariner 10, but this new image mosaic is the highest-resolution color imaging ever acquired of any portion of Mercury's surface. The largest impact feature at the top of the image is about 83 miles in diameter and is named Polygnotus, after a Greek painter from the fifth century B.C.


About 58 minutes before the Messenger's closest approach to Mercury Oct. 6, 2008, this close-up image of a portion of Mercury's surface was captured -- imaged by spacecraft for the first time during this flyby. The features in the foreground (near the right side of the image) are close to the terminator, which is the line between the sunlit day side and dark night side of the planet. This makes shadows long and prominent. Two very long scarps, or cliffs, are visible in this region, and the scarps appear to crosscut each other. The easternmost scarp also cuts through a crater, showing that it formed after the impact that created the crater.

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NASA's Messenger spacecraft captured this view of Mercury's rugged, cratered landscape as illuminated by the sun on Jan. 14, 2008. It shows a region 300 miles across, including craters less than a mile wide.


Machaut is the name of a crater, approximately 60 miles in diameter, first seen under high-sun conditions by Mariner 10 in the 1970s. The crater is named for the medieval French poet and composer Guillaume de Machaut. This image shows a new view of Machaut taken during the Messenger's second flyby of Mercury Oct. 6, 2008. The slanting rays of the sun cast shadows that reveal numerous small craters and intricate features. The largest crater within Machaut appears to have been inundated by lava flows similar to those that have filled most of the floor of the larger feature. The adjacent, slightly smaller crater was formed at a later time and excavated material below the lava-formed surface.


Recently named after the 12th century Chinese artist, the Xiao Zhao crater on the central left side of this image is small in comparison with many other craters on Mercury. The fresh, bright rays, which were created during the impact that formed the crater, indicate that Xiao Zhao is a relatively young crater on Mercury's surface.


This image of Mercury passing in front of the sun was captured Nov. 8 by the Solar Optical Telescope.

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This full-resolution image suggests the different compositions and nature of regions on Mercury's surface. As seen here, smooth young plains cover the lower topography on the left. Dark and relatively blue material was ejected from the 165 mile-diameter crater on the lower right, covering the older, smooth plains. A small crater then formed and rose through the blue material to reveal more smooth plains beneath. The total width of the scene is 385 miles.


An image of the planet Mercury captured during a January 2008 flyby by the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft. The image shows that volcanoes were involved in the formation of the planet's plains.


Mercury, the closest planet to the sun, remains the most mysterious of the solar system's inner planets. The only spacecraft to explore Mercury close-up was Mariner 10, which executed three flybys of Mercury in 1974 and 1975, surveying approximately 45 percent of its surface. Its highest resolution photographs recorded features approximately a mile across. A reprocessing of the Mariner 10 data has resulted in this dramatic mosaic.


Astronomer Phil Jones recorded this detailed image of the sun. Left of center, the tiny disk of Mercury seems to be imitating a small sunspot that looks a little too round. (panasnya rupa dia)