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Title: The effects of the target material properties and layering on the crater chronology: the case of Raditladi and Rachmaninoff basins on Mercury
Authors: S. Marchi (1), M. Massironi (2), G. Cremonese (3), E. Martellato (4), L. Giacomini (2), L. Prockter (5) ((1) Observatoire de la Cote d'Azur, (2) Padova University, (3) INAF, (4) CISAS, (5) APL, Johns Hopkins University)

In this paper we present a crater age determination of several terrains associated with the Raditladi and Rachmaninoff basins. These basins were discovered during the first and third MESSENGER flybys of Mercury, respectively. One of the most interesting features of both basins is their relatively fresh appearance. The young age of both basins is confirmed by our analysis on the basis of age determination via crater chronology. The derived Rachmaninoff and Raditladi basin model ages are about 3.6 Ga and 1.1 Ga, respectively. Moreover, we also constrain the age of the smooth plains within the basins' floors. This analysis shows that Mercury had volcanic activity until recent time, possibly to about 1 Ga or less. We find that some of the crater size-frequency distributions investigated suggest the presence of a layered target. Therefore, within this work we address the importance of considering terrain parameters, as geo-mechanical properties and layering, into the process of age determination. We also comment on the likelihood of the availability of impactors able to form basins with the sizes of Rachmaninoff and Raditladi in relatively recent times.

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Mercury south pole
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The MESSENGER orbiter acquired this image of Mercurys south pole on the 4th May, 2011. 

mercurySouthpole1b.jpg

 

 

This WAC image shows the south pole at the center, 0° longitude at the top, and 90° E longitude to the right. The image extends to -70° latitude in all directions.

Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -85.02°
Center Longitude: 261.0° E
Resolution: 1500 meters/pixel
Scale: The diameter of this polar projection is 1,700 kilometres

Expand (271kb, 1280 x 1280)
Credit NASA/JPL

 



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Title: On the first determination of Mercury's perihelion advance
Authors: Diana Rodica Constantin

The first determination of the perihelion advance of Mercury's orbit was obtained by Leverrier from the analysis of the transit contacts of the planet on the solar disk. He obtained for the advance the value \delta \pi ' = 38".3/century, considering that the value \delta e', namely the correction of the variation of the planet's orbit eccentricity, is negligible. In this paper \delta \pi ' and \delta e' are calculated by the least squares method, on the basis of the meridian observations used by Leverrier. Thus, we obtain for advance the value \delta \pi ' = 42".8/century, which is close to the one given in the theory of general relativity. The same, we obtained the value \delta e' = -0".044/year, which is lower in absolute value than Leverrier's estimation \delta e' = -0".0806/year.

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First Color Image of Mercury from Orbit
2011-03-30
First NAC Image Obtained in Mercury Orbit
2011-03-30
Simply Beautiful
2011-03-30
Smooth Plains in Mercury's North
2011-03-30
From Orbit, Looking toward Mercury's Horizon
2011-03-30
MESSENGERs Wide-Angle Camera
2011-03-30
A First Look at Terrain Near Mercury's North Pole
2011-03-30
Exploring the Rays of Debussy
2011-03-30
An Annotated Guide to the First Orbital Image
2011-03-30


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First Ever Image From Orbit Of Mercury

Following insertion into Mercury's orbit on March 17, Messenger has finally sent home the first images ever recorded from within the orbit of our innermost planet.
Currently, Messenger is the commissioning phase of the mission and is testing out its various equipment and instruments. In a few days, it will begin its year-long primary mission which will answer questions about the formation and composition of the smallest and innermost planet in our solar system.

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Debussyb.jpg
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Credit NASA/JPL

The dominant rayed crater in the upper portion of the image is Debussy. The smaller crater Matabei with its unusual dark rays is visible to the west of Debussy. The bottom portion of this image is near Mercury's south pole and includes a region of Mercury's surface not previously seen by spacecraft.

Source NASA



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MESSENGER Sends Back First Image of Mercury from Orbit

MESSENGER has delivered its first image since entering orbit about Mercury on March 17. It was taken today at 5:20 am EDT by the Mercury Dual Imaging System as the spacecraft sailed high above Mercury's south pole, and provides a glimpse of portions of Mercury's surface not previously seen by spacecraft. The image was acquired as part of the orbital commissioning phase of the MESSENGER mission. Continuous global mapping of Mercury will begin on April 4.

Debussyb.jpg
Expand (190kb, 1024 x 1024)
Credit NASA/JPL
An image of Debussy crater, near the southern pole of Mercury, the first image from Mercury orbit ever captured by a space probe.

Date acquired: March 29, 2011
Image Mission Elapsed Time (MET): 209877871
Image ID: 65056
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -62.1°
Center Longitude: 18.4° E
Resolution: 2.7 kilometres/pixel
Scale: Debussy has a diameter of 80 kilometres



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First Orbital Image Planned for March 29

MERCURY1.jpg

The graphic shown here outlines in yellow the planned footprint for the first image to be acquired from a spacecraft orbiting Mercury. The image will be obtained as MESSENGER is high above Mercury's south pole and will include a portion of Mercury's surface not previously seen by spacecraft.
This first planned image is scheduled to be taken on March 29, 2011, 7:40 UTC, or 3:40 am EDT. Over the subsequent six hours, MESSENGER will acquire 364 images in total before beginning to downlink the data to Earth.



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MESSENGER in Orbit around Mercury
For the first time, Earth has a regular orbiting eye-in-the-sky spying on the solar system's smallest and strangest planet, Mercury. NASA's spacecraft called Messenger successfully veered into a pinpoint orbit Thursday night after a 6˝-year trip and 7.9 billion kilometres and tricky manoeuvring to fend off the gravitational pull of the sun.
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Mercury has never been orbited by a spacecraft before. That will change this month

The old joke goes that the only thing worse than finding a worm in an apple is finding half a worm. Planetary scientists had a similar feeling on March 29, 1974, when the Mariner 10 space probe flew by Mercury and gave humanity its first good look at this tiny inferno of a world. It discovered, among other features, one of the largest impact basins in the solar system, later named Caloris. Yet its pictures captured only half the basin; the other half remained cloaked in darkness. In fact, between this visit and the second and third flybys later in 1974 and in 1975, Mariner 10 imaged less than half the planets surface.
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