Part of a stereographic projection of Mercury’s north pole
Talk about northern exposure! This is a section of a much larger image, released today by the MESSENGER team, showing the heavily-cratered north pole of Mercury as seen by the MESSENGER spacecraft’s Mercury Dual Imaging System (MDIS) instrument.
See the full-size image below:
Many MDIS images were averaged together to create a mosaic of Mercury’s polar region, which this stereographic projection is centered on. MESSENGER is at its lowest altitude as it passes over Mercury’s northern hemisphere — about 200 kilometers (124 miles), which is just a little over half the altitude of the ISS.
The largest centrally-peaked crater near the center is Prokofiev, named after a 20th-century Russian composer. Approximately 110 km (68 mi.) in diameter, its permanently-shadowed interior is home to radar-bright deposits that are thought to contain water ice.
Even though Mercury is almost three times closer to the Sun than Earth is and hosts searing daytime temperatures of 425ºC (800ºF), there’s virtually no atmosphere to hold or transmit that heat. Nighttime temperatures can reach as low as -185ºC (-300ºF), and since a day on Mercury is 176 Earth days long it gets very cold for quite a long time!
Also, because Mercury’s axis of rotation isn’t tilted like Earth’s, low elevation areas near the poles receive literally no sunlight. Unless vaporized by a meteorite impact any ice gathered inside these deep craters would remain permanently frozen.
Here’s an orthographic projection of the image above, showing what the scene would look like on Mercury — that is, if it was ever fully lit by the Sun, which it isn’t.
Many of the craters on Mercury’s north pole have recently been named after famous artists, authors and composers, such as Kandinsky, Stieglitz, Goethe, and even one named after J.R.R. Tolkien. You can see an annotated image showing the names of Mercury’s north polar craters here.
On November 29, NASA will host a news conference at 2 p.m. EST to reveal new observations from MESSENGER, the first spacecraft to orbit Mercury. The news conference will be carried live on NASA Television and the agency’s website… you can tune in on NASA TV here.
Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
The southern portion of Mercury’s Vivaldi basin and outlying rugged terrain
Named for the 17th-century Venetian composer, the southern half of Mercury’s Vivaldi basin is seen in this image acquired on August 26 by NASA’s MESSENGER spacecraft. The 213-km (132-mile) -wide crater’s smooth floor is contrasted by the incredibly rugged terrain beyond its outermost ring — a result of the ejected material that was flung out from the impact site and emphasized by the low angle of illumination.
The floor of the crater remained relatively smooth due to molten material that erupted in the wake of the impact event, flooding the basin.
Recent findings from the MESSENGER mission have revealed variations in Mercury’s surface composition due to volcanism that occurred at different times, as well as a surprising concentration of elements like magnesium and sulfur — much more so than any of the other terrestrial planets.
In results to be published in the Journal of Geophysical Research, scientists report that Mercury’s volcanic smooth plains differ in composition from older surrounding terrains. The older terrain has higher ratios of magnesium to silicon, sulfur to silicon, and calcium to silicon, but lower ratios of aluminum to silicon, suggesting that the smooth plains material erupted from a magma source that was chemically different from the source of the material in the older regions, according to Shoshana Weider of the Carnegie Institution of Washington, the lead author on the paper.
Mercury’s surface was also found to be high in magnesium and sulfur-enriched minerals.
“None of the other terrestrial planets have such high levels of sulfur. We are seeing about ten times the amount of sulfur than on Earth and Mars,” Weider said. “In terms of magnesium, we do have some materials on Earth that are high in magnesium. They tend to be ancient volcanic rocks that formed from very hot lavas. So this composition on Mercury tells us that eruptions of high-temperature lavas might have formed these high-magnesium materials.”
The data was gathered with MESSENGER’s X-Ray Spectrometer (XRS) — one of two instruments designed to measure the abundances of many key elements in the top 2mm of Mercury’s crust. XRS detects emissions from elements in the 1-10 kiloelectron-volt (keV) range – specifically, magnesium, aluminum, silicon, sulfur, calcium, titanium, and iron.
Inset image: A global mosaic of Mercury from MESSENGER (2011). Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Here’s a little something to please fans of space, art and fantasy alike (and those who enjoy all three): on August 6 the International Astronomical Union approved names for 9 craters on Mercury, one of which is named for J.R.R. Tolkien, revered author of The Hobbit and The Lord of the Rings (among other seminal fantasy works.)
The crater Tolkien is approximately 30 miles (48 km) in diameter. All 9 newly-named craters are located in Mercury’s north polar region and exhibit radar evidence of water ice hidden in their shadowy pocketses.
IAU procedure for craters on Mercury has them named after “deceased artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field and have been recognized as art historically significant figures for more than 50 years.” Find out who all 9 new craters are named for after the jump:
Egonu, for Uzo Egonu (1931-1996), a Nigerian-born painter who at 13 was sent to England to study art, first at a private school in Norfolk and later at the Camberwell School of Arts and Crafts. Exile, alienation, and the pain of displaced peoples were recurrent themes in his work.
Gaudí, after Antoni Gaudí (1852-1926), a Spanish architect whose work concentrated largely on the Catalan capital of Barcelona. He was very skilled with ceramics, stained glass, wrought-iron forging, and carpentry and integrated these crafts into his architecture.
Kandinsky, for Wassily Kandinsky (1866-1944), a Russian painter and art theorist credited with painting the first purely abstract works.
Petronius, for Titus Petronius (c. AD 27-66), a Roman courtier during the reign of Nero. He is generally believed to be the author of the Satyricon, a satirical novel believed to have been written during the Neronian era.
Prokofiev, for Sergei Prokofiev (1891-1953), a Russian composer, pianist, and conductor who is considered one of the major composers of the 20th century. His best-known works include the ballet Romeo and Juliet — from which “Dance of the Knights” is taken — and Peter and the Wolf.
Tolkien, for John Ronald Reuel (J. R. R.) Tolkien (1892-1973), an English writer, poet, philologist, and university professor, best known as the author of the classic fantasy novels The Hobbit and The Lord of the Rings.
Tryggvadóttir, for Nina Tryggvadóttir (1913-1968), one of Iceland’s most important abstract expressionist artists and one of very few Icelandic female artists of her generation. She primarily worked in painting, but she also created collages, stained glass work, and mosaics.
Qiu Ying, for Shifu Qiu Ying (1494-1552), a Chinese painter who specialized in the gongbi brush technique, a careful realist method in Chinese painting. He is regarded as one of the Four Great Masters of the Ming Dynasty.
Yoshikawa, for Eiji Yoshikawa (1892-1962), a Japanese historical novelist best known for his revisions of older classics including The Tale of the Heike, Tale of Genji, Outlaws of the Marsh, and Romance of the Three Kingdoms.
“These designations expand the opportunities to recognize the contributions to the arts by the most creative individuals from many cultures and eras. The names of those individuals are now linked in perpetuity to the innermost planet.”
– Sean Solomon, MESSENGER Principal Investigator
The craters were imaged by NASA’s MESSENGER spacecraft, currently in extended mission around Mercury. Learn more about the preciousss MESSENGER mission here. (Gollum! Gollum!)
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Although composited from expanded wavelengths of light, this wide-angle image from NASA’s MESSENGER spacecraft shows the amazing variation of colors and tones to be found on Mercury’s Sun-scoured surface.
This scene lies between Mercury’s Moody and Amaral craters, spanning an area of about 1200 km (745 miles). The patch of dark blue Low Reflectance Material (LRM) in the upper left of the image and the bright rayed crater on the right make this a diverse view of Mercury’s surface. Note the curious small, dark crater just below the bright rayed crater on the right.
Dark LRM material is thought to indicate the presence of a mineral called ilmenite, which is composed of iron and titanium and has been revealed through volcanic, cratering and erosion processes.
Did you know that until MESSENGER arrived in 2008 half of Mercury had never been seen? And that although Mercury is the closest planet to the Sun there may still be water ice on its surface? Learn more about these and other fascinating facts about Mercury here.
Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
As the world turns its gaze outward in anticipation of the arrival of Mars Science Laboratory — with its hair-raising “seven minutes of terror” landing — let’s take a moment to look back inward, where MESSENGER is still faithfully orbiting the first rock from the Sun, Mercury, and sending back images that could only have been imagined just a few years ago.
The image above shows the graben-gouged terrain around Balanchine crater, within Mercury’s vast Caloris Basin impact crater. Named for the co-founder of the New York City Ballet, Balanchine crater is 41 km (25.5 miles) in diameter and filled with the curious erosion features known as hollows. Graben — basically sunken troughs in the surface — are the result of extensional forces that have pulled sections of the planet’s upper crust apart.
This image shows the peak-ring structure located within the much larger crater Rustaveli, which is 180 km (112 miles) in diameter. One of the more recently-named craters (the IAU convention for new features on Mercury has them titled after renowned artists, writers and composers from history) Rustaveli is named for a 12th-century Georgian poet who wrote the epic “The Knight in the Panther’s Skin”. The crater that now bears his namesake is located on Mercury’s northern hemisphere.
These two craters — also located within Caloris Basin — don’t yet have names but are no less interesting. Their overlapping positions works like an optical illusion, making the newer,sharper-edged crater on the right seem to almost float above the surface. The false-color of the image highlights the difference in surface composition of the two craters, which are both about 40 km (24 miles) wide. (The Caloris Basin in which they reside, however, is one of the largest known impact sites in our solar system, measuring at 1550 km — 963 miles — across!)
Now we zoom out for a wider view of our solar system’s second-densest planet (Earth is the first) and take a look at an image that’s night and day — literally! This is Mercury’s terminator, the twilit dividing line between night and day. More than just making a pretty picture, data on this transition is valuable to scientists as some atmospheric phenomena can only be observed at the terminator, such as the interaction between surface dust and charged particles from the Sun (which, at less than half the distance to the Sun than we are, Mercury is constantly bathed in.)
And now to zoom back in, we get a good look at an unnamed central-peaked crater about 85 km (52 miles) across in an oblique view that highlights the hollows and depressions within its floor. Acquired as part of what’s called a “targeted observation”, high-resolution images like this (79 meters/pixel) allow scientists to closely investigate specific features — but sadly there’s just not enough mission time to image all of Mercury at this level of detail.
On March 17, 2011 (March 18, 2011, UTC), MESSENGER became the first spacecraft ever to orbit Mercury. The mission has provided the first data from Mercury since Mariner 10, over 30 years ago. After over 1,000 orbits, 98 percent of Mercury is now imaged in detail, allowing us to know more about our solar system’s innermost world than ever before.
Keep up with MESSENGER updates (and the latest images) on the mission website here.
Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This collection of craters, shaped not unlike the iconic head of a certain cartoon mouse, was imaged by NASA’s MESSENGER spacecraft on June 3, 2012.
All together now: C-R-A, T-E-R… M-O-U-S-Eeeeee…
Acquired as part of MESSENGER’s extended mission to map Mercury’s surface in higher detail, the image above isn’t map-projected; that is, it’s not aligned with north as up. In reality the large crater that makes up Mickey’s “head” is north of the two “ears”.
Still, this is one big mouse head — the large crater in the center has a diameter of approximately 105 km (65 miles)!
Read more about this and see many other images of the first rock from the Sun on the MESSENGER mission site here.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Warhol crater, one of 23 recently named craters on Mercury
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As pop art icon Andy Warhol said, “In the future everyone will be famous for fifteen minutes,” and so here’s an image of the crater on Mercury that now bears his name, set up in the style of one of his multicolored silkscreens.
Warhol is one of 23 craters on Mercury to be recently approved for names by the International Astronomical Union (IAU), joining other notable artists, authors and musicians like Gustav Holst, Rene Magritte and Dr. Seuss who now have craters named in their honor on the first rock from the Sun.
95 km (59 miles) in diameter, Warhol crater features a large, elongated central peak, stepped walls and many of the curious erosions known as hollows.
The original image, seen at top left, was acquired by NASA’s MESSENGER spacecraft on October 21, 2011, using its Wide-Angle Camera Mercury Dual Imaging System (MDIS) instrument.
With the new list of 23 named craters, there are now 76 officially (and artistically) titled craters on Mercury since MESSENGER’s first pass of the planet in January 2008.
See the original release by the MESSENGER mission team here.
“I’m bored with that line. I never use it anymore. My new line is “In 15 minutes everybody will be famous.”
– Andy Warhol (1928 – 1987)
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
MESSENGER image of Mercury, acquired with its Wide Angle Camera on March 21, 2012.
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The subtle yet surprisingly varied colors of Mercury are revealed in the latest images from NASA’s MESSENGER spacecraft, now in its extended mission and second year in orbit.
The image above, a composite of Wide Angle Camera images acquired in 996, 748 and 433 nanometers for red, green and blue, shows a semi-lit limb of Mercury with the bright rayed crater Debussy visible at left. (The image has been rotated 180 degrees from the original, and color saturation was boosted by 25%.)
Named for the French composer Claude Debussy of “Claire de Lune” fame, the crater itself is approximately 50 miles (80 km) wide. It was first detected by ground-based radar telescopes in 1969 as a bright spot.
Now, 43 years later, we have a spacecraft in orbit sending back images like this. Amazing.
The various colors seen across Mercury are due to different mineral compositions of the geologic regions. The exact compositions are not yet known, and the current puzzle that researchers are trying to solve with MESSENGER is to figure out what materials make up Mercury’s complex, multi-hued surface. That will also give a clue as to what’s inside the planet and how it evolved… as well as how it is currently evolving today.
The image below is from MESSENGER’s Visual and Infrared Spectrograph (VIRS) and shows a map of Mercury’s surface, with RGB colors corresponding to different mineralogical compositions.
Sinusoidal equal area projection map of Mercury from MESSENGER's VIRS instrument.
Younger surface materials that are brighter at visible wavelengths and less affected by space weathering show up in reds, yellows and greens. Materials that may have relatively higher iron contents show up in blue.
These are Mercury’s “other colors”… maybe not what we would see with our own eyes, but beautiful nonetheless to planetary scientists!
See the above image on the MESSENGER website here.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Until relatively recently, Mercury was one of the most poorly understood planets in the inner solar system. The MESSENGER mission to Mercury, is changing all of the that. New results from the Mercury Laser Altimeter (MLA) and gravity measurements are showing us that the planet closest to our sun is thin skinned and wrinkled, which is very different from what we originally thought.
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was launched back in 2004. It took a long time getting to its destination, completing 3 flybys of Mercury before finally entering orbit a little over a year ago. Currently, the spacecraft is in a highly eccentric polar orbit, approaching the planet much closer in the north than in the south. This allows the northern hemisphere to be probed and imaged at enviably high resolutions, but leaves the southern hemisphere poorly understood.
Even so, the data returned from MESSENGER is showing us some quite unanticipated findings. Two papers from the MESSENGER team, published in today’s issue of Science, are showing some surprising results from the laser altimeter and gravity experiments.
Using NASA’s Deep Space Network, Earth-based radio tracking of MESSENGER has allowed minute changes in the spacecraft’s orbit to be monitored and recorded. From this, Dr. Maria Zuber of MIT and her team calculated a model of Mercury’s gravity. Meanwhile, the on-board laser altimeter has provided invaluable topographic information. Combined together, these data have allowed the MESSENGER team to glean a great deal of information about the planet’s interior workings.
One of the most striking findings is that the iron-rich core of Mercury is very large. A combination of measurements and models suggest that the core has both a solid interior portion and a liquid outer portion. And while it is not certain how much of the core is solid and how much is liquid, it is clear that the total core has a radius of about 2030 km. This is a huge core, representing 83% of Mercury’s 2440 km radius!
The internal structure of Mercury is very different from that of the Earth. The core is a much larger part of the whole planet in Mercury and it also has a solid iron-sulfur cover. As a result, the mantle and crust on Mercury are much thinner than on the Earth. Credit: Case Western Reserve University
Furthermore, these calculations suggest that the layer above the core is much denser than previously expected. Results from MESSENGER’s X-Ray spectrometer indicate that the crust, and by extension the mantle, are too low in iron to explain this high density. Dr. Zuber’s team think that the only way to explain this discrepancy is by the presence of a solid iron-sulfur layer just above the core. Such a layer could be anywhere from 20 to 200 km thick, leaving only a very thin crust and mantle at the top. This kind of interior structure is completely different from what was originally suggested for Mercury, and it is nothing like what we have seen in the other planets!
This striking fact may help explain some unexpected altimeter results, which show that Mercury’s topography has less variation than other planets. The total difference between the highest and lowest elevations on Mercury is only 9.85 km. Meanwhile, the Moon has a total difference of 19.9 km between its highest and lowest points, and on Mars this difference is 30 km. Dr. Zuber and her team speculate that the presence of the core so close to the surface could keep the mantle hot, allowing topographic features to relax. In such a scenario, the lithosphere under tall impact-formed mountains would sink down into a mushy mantle that cannot support their weight. Conversely, the thin lithosphere under impact basins would rebound upwards, taking part of the mobile mantle with it.
In fact, the gravity data shows evidence of exactly this kind of process, in the form of “mascons”. These mass concentrations form when large imacts make the local crust very thin, allowing denser mantle material to rise closer to the surface as the lithosphere rebounds from the impact event. Mascons are well known from studies on the Moon and Mars, and now MESSENGER’s gravity data has revealed three such mascons on Mercury, located in the Caloris, Sobkou, and Budh basins.
The elliptical polar orbit of the MESSENGER spacecraft means that measurements at the North Pole of Mercury are much better than those at the South Pole, or even at the equator. This is evident in the better spatial resolution that can be seen at the high latitudes in this elevation map of the northern hemisphere. Major impact structures are identified by black circles. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Interestingly enough, the mascons in Sobkou and Budh basins are not immediately obvious. They only show up when the effects of a regional topographic high are adjusted for. This topographic feature is a large quasi-linear rise that extends over half the circumference of Mercury in the mid-latitudes. The rise even passes through the northern part Caloris basin (which is large enough that its mascon is not overwhelmed by the rise). Studies of this rise by the MESSENGER team suggest that it is relatively young, having formed well after the formation of the basins, after the volcanic flooding of their interiors and exteriors, and even after some of the later impact craters that cover the flooded surfaces.
Dr. Zuber and her team also identified another young topographically elevated region, the Northern Rise, located in the lowlands surrounding the North Pole. They speculate that these young rises represent a buckling of the lithosphere, which happened when the planet’s interior cooled and contracted. This interpretation is supported by the presence of lobate scarps and ridges that can be seen around the planet, and which represent faulting of the crust when it was compressed.
So, it seems that Mercury is unlike the other planets of the Solar System. It appears to have a disproportionately large core that is covered by a thin skin of mantle and lithosphere. Furthermore, this skin seems to have wrinkled like a raisin’s when the huge core of the planet shrunk as it cooled.
Sources
Gravity Field and Internal Structure of Mercury from MESSENGER, Smith et al., Science V336 (6078), 214-217, April 13 2012, DOI:10.1126/science.1218809
Topography of the Northern Hemisphere of Mercury from MESSENGER Laser Altimetry, Zuber et al., Science V336 (6078), 217-220, April 13 2012, DOI:10.1126/science.1218805
Named after the 17th-century metaphysical poet, Mercury’s Donne crater was captured in this image by NASA’s MESSENGER spacecraft. The 53-mile (83-km) -wide crater features a large, rounded central peak and numerous lobate scarps lining its floor.
Lobate scarps are found all across Mercury. Visible above as arc-shaped ridges, they are most likely thrust faults resulting from surface compression and contraction.
Donne’s central peak has been well-eroded by impacts into a softly rolling mound. Central peaks are common features of larger craters, thought to be formed when the excavation of material during an impact springs the crater floor upwards — a process called “isostatic rebound”.
This image was acquired by MESSENGER’s Narrow-Angle Camera (NAC) on August 2, 2011.
On March 17 MESSENGER successfully wrapped up a year-long campaign to perform the first complete reconnaissance of the geochemistry, geophysics, geologic history, atmosphere, magnetosphere, and plasma environment of Mercury. The following day, March 18, marked the official start of its extended phase designed to build upon those discoveries.
“Six plus years of cruise operations, capped by a year of nearly flawless orbital operations, with an additional year of scientific return ahead in the harsh environment at 0.3 astronomical units (27,886,766 miles) from the Sun,” said MESSENGER Mission Systems Engineer Eric Finnegan at JHU/APL. All this “achieved with a 1,000 kg satellite, designed, built, and launched in less than four years for a total mission cost of less than $450 million.”
Well “Donne”, MESSENGER!
Read more about the MESSENGER mission’s extension here.
Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
This scene lies between Mercury’s Moody and Amaral craters, spanning an area of about 1200 km (745 miles). The patch of dark blue Low Reflectance Material (LRM) in the upper left of the image and the bright rayed crater on the right make this a diverse view of Mercury’s surface. Note the curious small, dark crater just below the bright rayed crater on the right.
