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Characterizing The Surface Composition Of Mercury

September 18, 2012 Leave a comment

The MESSENGER spacecraft, which has been orbiting Mercury since March 2011, has been revealing new information about the surface chemistry and geological history of the innermost planet in the solar system. Weider et al. recently analyzed 205 measurements of the surface composition from MESSENGER’s X-ray spectrometer, focusing on the large expanse of smooth volcanic plains at high northern latitudes and surrounding areas that are higher in crater density and therefore older than the northern plains.

In general, the measurements show that Mercury’s surface composition is very different from that of other planets in the solar system. It is dominated by minerals high in magnesium and enriched in sulfur.

Full Story: http://www.agu.org/news/press/jhighlight_archives/2012/2012-09-17.shtml#one

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MESSENGER Marks 8th Anniversary Of Launch


The MESSENGER spacecraft launched eight years ago today — on August 3, 2004 — embarking on a six-and-a-half year journey to become the first spacecraft to orbit Mercury. The spacecraft’s 4.9-billion mile (7.9-billion kilometer) cruise to history included 15 trips around the Sun, a flyby of Earth, two flybys of Venus, and three flybys of Mercury.

MESSENGER made history on January 14, 2008, when it flew over a portion of Mercury that had never before been seen at close range. In this first of three flybys of the planet, the probe’s cameras took 1,213 images and other sophisticated instruments made the first spacecraft measurements of the planet and its environment since Mariner 10’s third and final flyby on March 16, 1975.

The mission’s penultimate accomplishment — entering orbit about Mercury — was celebrated on March 17, 2011, by a crowd of hundreds gathered at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The event was covered live, and the webcast is still available online at http://messenger.jhuapl.edu/mer_orbit.html.

Full Story: http://messenger.jhuapl.edu/news_room/details.php?id=225

AGU Journal Highlights


The following highlights summarize research papers that have been recently published in Geophysical Research Letters (GRL), Journal of Geophysical Research-Space Physics (JGR-A), and Journal of Geophysical Research-Solid Earth (JGR-B).

In this release:

2. New images support proposal for water ice near Mercury’s south pole
Two decades ago, radio telescope observations showed radar-bright features in Mercury’s polar regions. The radar characteristics are similar to those of the icy satellites of Jupiter and at the south polar ice cap on Mars.

4. Wind may have driven avalanches on Martian dunes
In the sand dunes in the north polar sand sea of Mars, sand avalanches that appear as wedge-shaped alcoves can be seen above fan-shaped deposits. The avalanches, which are typically several meters across, are currently actively forming, with new alcoves showing up in recent images taken in consecutive Mars years.

7. Charged nanograins in the plume of Saturn’s moon Enceladus
Enceladus, which orbits Saturn in the planet’s E ring, is one of the few geologically active moons in the outer solar system. It emits a large plume that contains water-ice dust grains.

Full Story: http://www.agu.org/news/press/jhighlight_archives/2012/2012-05-31.shtml

MESSENGER Spacecraft Reveals New Insights on Planet Mercury

March 22, 2012 Leave a comment

Thanks to the MESSENGER spacecraft, and a mission that took more than 10 years to complete, scientists now have a good picture of the solar system’s innermost planet.

On March 17, MESSENGER (MErcury Surface, Space Environment, GEochemistry, and Ranging) completed its one-year primary mission, orbiting Mercury, capturing nearly 100,000 images, and recording data that reveals new information about the planet’s core, topography, and the mysterious radar bright material in the permanently shadowed areas near the poles. The findings are presented in two papers published online in Science Express.

“Mercury is the last unexplored planet,” said UC Santa Barbara physics professor emeritus Stanton Peale, who devised the procedure used for detecting whether or not Mercury had a liquid core. The way Mercury was formed, he said, may show some constraints on the formation of the solar system.

For one thing, Mercury’s core is larger than expected –– almost 85 percent of the planetary radius. The Earth’s core, in contrast, is just over half of the planet’s radius. Additionally, Mercury appears to have a more complex core than Earth’s –– a solid iron sulfide layer that is now part of the mantle, which encases a liquid core, which may float on a solid inner core.

Full Story: http://www.ia.ucsb.edu/pa/display.aspx?pkey=2677

Mercury Transits Yield Precise Solar Radius

March 21, 2012 Leave a comment

Image Credit: NASA

Image Credit: NASA

A group of scientists from Hawaii, Brazil and California has measured the diameter of the Sun with unprecedented accuracy by using a spacecraft to time the transits of the planet Mercury across the face of the Sun in 2003 and 2006.

They measured the Sun’s radius as 696,342 km (432,687 miles) with an uncertainty of only 65 km (40 miles). This was achieved by using the solar telescope aboard a NASA satellite, thereby bypassing the blurring caused by Earth’s atmosphere that occurs when observations are made from the ground.

The measurements of the Sun’s size were made by University of Hawaii Institute for Astronomy scientists Drs. Marcelo Emilio (visiting from Ponta Grossa, Brazil), Jeff Kuhn and Isabelle Scholl in collaboration with Dr. Rock Bush of Stanford University. They used the Michelson Doppler Imager (MDI) aboard NASA’s Solar and Heliospheric Observatory (SOHO) to make the measurements.

“Transits of Mercury occur 12-13 times per century, so observations like this allow us to refine our understanding of the Sun’s inner structure, and the connections between the Sun’s output and Earth’s climate,” said Kuhn.

Full Story: http://www.ifa.hawaii.edu/info/press-releases/solar_radius/

Lutetia Is Rare Survivor from Birth of Earth

November 15, 2011 Leave a comment

Credit:  ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

New observations indicate that the asteroid Lutetia is a leftover fragment of the same original material that formed the Earth, Venus and Mercury. Astronomers have combined data from ESA’s Rosetta spacecraft, ESO’s New Technology Telescope, and NASA telescopes. They found that the properties of the asteroid closely match those of a rare kind of meteorites found on Earth and thought to have formed in the inner parts of the Solar System. Lutetia must, at some point, have moved out to its current location in the main asteroid belt between Mars and Jupiter.

A team of astronomers from French and North American universities have studied the unusual asteroid Lutetia in detail at a very wide range of wavelengths [1] to deduce its composition. Data from the OSIRIS camera on ESA’s Rosetta spacecraft [2], ESO’s New Technology Telescope (NTT) at the La Silla Observatory in Chile, and NASA’s Infrared Telescope Facility in Hawaii and Spitzer Space Telescope were combined to create the most complete spectrum of an asteroid ever assembled [3].

This spectrum of Lutetia was then compared with that of meteorites found on Earth that have been extensively studied in the laboratory. Only one type of meteorite — enstatite chondrites— was found to have properties that matched Lutetia over the full range of colours.

Full Story: http://www.eso.org/public/news/eso1144/

MESSENGER Results After 6 Months in Mercury Orbit

October 7, 2011 Leave a comment

MESSENGER scientists will highlight the latest results on Mercury from MESSENGER observations obtained during the first six months (the first Mercury solar day) in orbit. These findings will be presented October 5 in 30 papers and posters as part of a special session of the joint meeting of the European Planetary Science Congress and the Division for Planetary Sciences of the American Astronomical Society in Nantes, Frances.

Scientists will also look ahead to MESSENGER observations still to come and to the dual-spacecraft BepiColombo mission of the European Space Agency and the Japan Aerospace Exploration Agency’s later this decade.

“This is the first major scientific meeting at which MESSENGER orbital observations are being presented to the scientific community,” says MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. “As the first spacecraft to orbit our solar system’s innermost planet, MESSENGER continues to reveal new surprises every week. It is timely to sum up what we’ve learned so far and to seek feedback from our international colleagues across planetary science on our interpretations to date.”

Full Story: http://www.europlanet-eu.org/outreach/index.php?option=com_content&task=view&id=356&Itemid=41