* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Solar System -> Mercury
Post Info
TOPIC: Mercury
Blobrana


L

Posts: 131433
Date:
RE: Mercury
Permalink  
 

The International Astronomical Union (IAU) have approved new names for features discovered on the planet Mercury. These new named features were discovered on the images taken by the  MESSENGER spaceprobe during its Mercury flyby in January 2008.
Rules for naming exist for the majority of the features on planets, the moons, and the asteroids. The Mercury cliffs are named after the boats of  famous explorers.  
Cliffs discovered by MESSENGER (rupes,  Latin  for cliffs) have been called Beagle Rupes, after the name of the boat on which the naturalist Charles Darwin sailed around the world.

Craters: Apollodorus, Atget, Cunningham, Eminescu, Kertész, Neruda, Raditladi, Sander, Sveinsdóttir, Xiao Zhao
Rupes: Beagle Rupes
Fossae: Pantheon Fossae
Read more


__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

 Last week, the MESSENGER team learned that the impact crater seen in the middle of this Narrow Angle Camera (NAC) image has been officially named Eminescu. The crater was named in honor of Mihai Eminescu, an accomplished and influential poet who is still considered the national poet of Romania. The MESSENGER team proposed the name to the International Astronomical Union (IAU), the authority that officially names surface features on planetary bodies.
Read more

__________________
Blobrana


L

Posts: 131433
Date:
Mozart crater
Permalink  
 

The Messenger spacecraft took this image of Mozart crater on January 14th during the spacecraft's first flyby of Mercury. Crater Mozart was discovered by Mariner 10 in the 1970s when the spacecraft visited Mercury.

Mozart
Expand (554kb, 1024 x 768)
Credit NASA

The new image of the crater reveals strange dark markings on the crater floor and dark rays crossing across the crater's rims. These subtle features were missed by Mariner 10.
Spectral data gathered by Messenger may reveal the composition of the crater. It is currently a mystery as to what the dark material is composed of; but it is probably similar to the dark halos found around other craters in nearby Caloris Basin.
Craters on Mercury are named after people who have made contributions to the arts.

__________________
Blobrana


L

Posts: 131433
Date:
RE: Mercury
Permalink  
 

Simulation reveals possible cause of Mercury's distinctive features
Patterns of scalloped-edged cliffs or lobate scarps on Mercury's surface are thrust faults that are consistent with the planet shrinking and cooling with time. However, compression occurred in the planet's early history and Mariner 10 images revealed decades ago that lobate scarps are among the youngest' features on Mercury. Why don't we find more evidence of older compressive features?
Scott D. King, professor of geosciences at Virginia Tech, reports in Nature Geoscience this week that mantle convection - loss of heat from the mantle through the crust has also played a role in the formation of lobate scarps on Mercury.
The gravity and topographic data from the MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) mission will test his hypothesis. In the meantime, King has created numerical simulations of the three-dimensional nature of convection within Mercury's silicate mantle. The computations were done using the Virginia Tech geoscience department's High-Performance Earth Simulation System, a high-speed, high-capacity 768-core Dell computing cluster.
Scientists have offered a number of explanations for global contraction on Mercury, such as cooling and core formation, tidal effects due to gravitation interactions with the Sun, impacts, and mantle convection.

"The idea that contraction due to cooling is the cause of these features has been around for a long time and makes a lot of sense. But the apparent pattern and the orientation of these features is puzzling. I can't really rule out the idea that this is just an artifact of the one hemisphere we have seen and the one camera/sun angle that we have pictures from. But the orientation of these features seems to require something additional, which I think is mantle convection" - Scott D. King

King noted that the upwellings from mantle convection on Mercury takes the form of long, linear rolls in distinctive clusters and directionality, rather than a random pattern associated with upthrusts from global compression acting alone.

"The pattern of convection I see in my Mercurian convection models is different from Venus, Mars, and Earth because the mantle is so much thinner - or the iron core is so much larger relatively speaking. On Venus, Earth, and Mars, the hot material coalesces into cylindrical plumes, not linear sheets. That could influence the tectonics at the surface and the convection within the iron core, which is most likely what is responsible for Mercury's magnetic field. The timing and orientation of these features are controlled by convection and not global contraction. Because the model suggests that mantle convection is still active today, gravity and topography data from the Messenger mission may be able to confirm the model" - Scott D. King.

King adds that the scarps almost certainly stopped deforming several billion years ago.

"The planet has cooled so much and the lithosphere is so thick that even if mantle convection still exists today, it will not modify the surface further. I think that if we want to figure out how the Earth got to be the way it is, we need to understand how the other planets got to be the way they are too."

Source: Virginia Tech

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

The MESSENGER spacecraft has detected a puzzling geological feature that scientists on Wednesday labelled "The Spider" and found evidence of past volcanic activity on Mercury. "The Spider" is made up of more than 100 narrow, flat-floored troughs radiating from a central point, like the legs of a spider.

spider
This Narrow Angle Camera (MDIS) image shows the feature nicknamed `the spider` found near the centre of the Caloris basin on January 14, 2008.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

The recent flyby of Mercury by NASA's MESSENGER spacecraft has given scientists an entirely new look at a planet once thought to have characteristics similar to those of Earth's moon. Researchers are amazed by the wealth of images and data that show a unique world with a diversity of geological processes and a very different magnetosphere from the one discovered and sampled more than 30 years ago.
Unlike the moon, the spacecraft showed that Mercury has huge cliffs with structures snaking up hundreds of miles across the planet's face. These cliffs preserve a record of patterns of fault activity from early in the planet's history. The spacecraft also revealed impact craters that appear very different from lunar craters.
Instruments provided a topographic profile of craters and other geological features on the night side of Mercury. The spacecraft also discovered a unique feature that scientists dubbed "The Spider." This formation never has been seen on Mercury before and nothing like it has been observed on the moon. It lies in the middle of a large impact crater called the Caloris basin and consists of more than 100 narrow, flat-floored troughs radiating from a complex central region.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: Mercurian impact ejecta: Meterorites and mantle
Authors: B. Gladman, J. Coffey

We have examined the fate of impact ejecta liberated from the surface of Mercury due to impacts by comets or asteroids, in order to study (1) meteorite transfer to Earth, and (2) re-accumulation of an expelled mantle in giant-impact scenarios seeking to explain Mercury's large core. In the context of meteorite transfer, we note that Mercury's impact ejecta leave the planet's surface much faster (on average) than other planet's in the Solar System because it is the only planet where impact speeds routinely range from 5-20 times the planet's escape speed. Thus, a large fraction of mercurian ejecta may reach heliocentric orbit with speeds sufficiently high for Earth-crossing orbits to exist immediately after impact, resulting in larger fractions of the ejecta reaching Earth as meteorites. We calculate the delivery rate to Earth on a time scale of 30 Myr and show that several percent of the high-speed ejecta reach Earth (a factor of -3 less than typical launches from Mars); this is one to two orders of magnitude more efficient than previous estimates. Similar quantities of material reach Venus.
These calculations also yield measurements of the re-accretion time scale of material ejected from Mercury in a putative giant impact (assuming gravity is dominant). For mercurian ejecta escaping the gravitational reach of the planet with excess speeds equal to Mercury's escape speed, about one third of ejecta re-accretes in as little as 2 Myr. Thus collisional stripping of a silicate proto-mercurian mantle can only work effectively if the liberated mantle material remains in small enough particles that radiation forces can drag them into the Sun on time scale of a few million years, or Mercury would simply re-accrete the material.

Read more (640kb, PDF)

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

As MESSENGER approached Mercury on January 14, 2008, the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) snapped this image of the crater Matisse in the southern hemisphere. Named for the French artist Henri Matisse, the Matisse crater was imaged during the Mariner 10 mission and is about 210 kilometres in diameter.

Matisse
Expand (322kb, 1024 x 1024)
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

On Mercury, craters are named for people, now deceased, who have made contributions to the humanities, such as artists, musicians, painters, and authors. The International Astronomical Union (IAU) oversees the official process of naming new craters and other new features discovered on bodies throughout the solar system. Scientists studying and mapping unnamed features can suggest names for consideration by the IAU.

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

see caption

New terrain on Mercury revealed by MESSENGER's cameras during the Jan. 14, 2008, flyby. Caloris Basin is circled.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

MESSENGER's Narrow Angle Camera (NAC) on the Mercury Dual Imaging System (MDIS) acquired this view of Mercurys surface illuminated obliquely from the right by the Sun. The unnamed crater (52 kilometres in diameter) in the centre of the image displays a telephone-shaped collapse feature on its floor. Such a collapse feature could reflect past volcanic activity at and just below the surface of this particular crater. MESSENGER team members are examining closely the more than 1200 images returned from this flyby for other surface features that can provide clues to the geological history of the innermost planet.

MERmESS_2
Expand (53kb, 560 x 442)
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The crater is located in the southern hemisphere of Mercury, on the side that was not viewed by Mariner 10 during any of its three flybys (1974-1975). This scene was imaged while MESSENGER was departing from Mercury from a distance of about 19,300 kilometres, about 1 hour after the spacecraft's closest encounter with Mercury. The image is of a region approximately 236 kilometres across, and craters as small as 1.6 kilometres can be seen.

__________________
«First  <  1 … 7 8 9 10 11  >  Last»  | Page of 11  sorted by
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Solar System -> Mercury


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard