MESSENGER: First Images from Mercury Orbit (more)

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MESSENGER: First Images from Mercury Orbit (more)

Post by bystander » Wed Mar 30, 2011 3:44 am

First Image Ever Obtained from Mercury Orbit
NASA JHU-APL CIW | MESSENGER | 2011 Mar 29
Early this morning, at 5:20 am EDT, MESSENGER captured this historic image of Mercury. This image is the first ever obtained from a spacecraft in orbit about the Solar System's innermost planet. Over the subsequent six hours, MESSENGER acquired an additional 363 images before downlinking some of the data to Earth. The MESSENGER team is currently looking over the newly returned data, which are still continuing to come down. Tomorrow, March 30, at 2 pm EDT, attend the NASA media telecon to view more images from MESSENGER's first look at Mercury from orbit.

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. Compare this image to the planned image footprint to see the region of newly imaged terrain, south of Debussy. Over the next three days, MESSENGER will acquire 1185 additional images in support of MDIS commissioning-phase activities. The year-long primary science phase of the mission will begin on April 4, and the orbital observation plan calls for MDIS to acquire more than 75,000 images in support of MESSENGER's science goals.

On March 17, 2011 (March 18, 2011, UTC), MESSENGER became the first spacecraft to orbit the planet Mercury. The mission is currently in its commissioning phase, during which spacecraft and instrument performance are verified through a series of specially designed checkout activities. In the course of the one-year primary mission, the spacecraft's seven scientific instruments and radio science investigation will unravel the history and evolution of the Solar System's innermost planet.

Visit the Why Mercury? section of this website to learn more about the science questions that the MESSENGER mission has set out to answer.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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Re: MESSENGER: First Image from Mercury Orbit

Post by Sam » Wed Mar 30, 2011 4:04 am

Congratulations to NASA and everyone involved!
And what an honor for Claude Debussy!
"No avian society ever develops space travel because it's impossible to focus on calculus when you could be outside flying." -Randall Munroe

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Re: MESSENGER: First Image from Mercury Orbit

Post by bystander » Wed Mar 30, 2011 8:08 pm

NASA JHU-APL CIW | MESSENGER | 2011 Mar 30

From Orbit, Looking toward Mercury's Horizon
MESSENGER acquired this image of Mercury's horizon as the spacecraft was moving northward along the first orbit during which MDIS was turned on. Bright rays from [url=Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]Hokusai[/url] can be seen running north to south in the image. MDIS frequently acquired images that contained Mercury's horizon during the mission's three Mercury flybys. (Visit these links to see examples of horizon images from Mercury flyby 1, Mercury flyby 2, and [url=Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington]Mercury flyby 3[/url].) However, now that MESSENGER is in orbit about Mercury, views of Mercury's horizon in the images will be much less common. The field of view for MDIS will generally be filled with Mercury's surface as the instrument maps out the planet's geology in high resolution, stereo, and color. Occasionally, in order to obtain images of a certain portion of Mercury's surface, the horizon will also be visible.
First Color Image of Mercury from Orbit
The first image acquired by MESSENGER from orbit around Mercury was actually part of an eight-image sequence, for which images were acquired through eight of the WAC’s eleven filters. Here we see a color version of that first imaged terrain; in this view the images obtained through the filters with central wavelengths of 1000 nm, 750 nm, and 430 nm are displayed in red, green, and blue, respectively. One of MESSENGER’s measurement objectives is to create an eight-color global base map at a resolution of 1 km/pixel (0.6 miles/pixel) to help understand the variations of composition across Mercury’s surface.
An Annotated Guide to the First Orbital Image
This historic first orbital image of Mercury was acquired 37 years to the day after Mariner 10’s historic first flyby of the innermost planet. Labels have been added to indicate several craters that were named based on Mariner 10 images, as well as Debussy, Matabei, and Berkel, which were named based on MESSENGER flyby images. The surface contained in the white lines is terrain previously unseen by spacecraft, and the star indicates the location of the south pole.
MESSENGER’s Wide-Angle Camera
The wide-angle camera (WAC) is not a typical color camera. It can image in 11 colors, ranging from 430 to 1020 nm wavelength (visible through near-infrared). It does this with a filter wheel: the 11 narrow-band filters (plus one clear filter) are mounted onto a wheel that can be rotated to allow the camera to capture an image through each filter. In this image the 1000 nm, 750 nm, and 430 nm filters are displayed in red, green, and blue, respectively. Several craters appear to have excavated compositionally distinct low-reflectance (brown-blue in this color scheme) material, and the bright rays of Hokusai crater to the north cross the image. During MESSENGER’s orbital operations, we will typically use just eight of the WAC's filters. This decision was made to reduce the amount of data that must be stored on the spacecraft’s solid-state recorder before the information can be downlinked. It’s also quicker than cycling through all 11 filters – the spacecraft is moving rapidly over the surface, and there isn't much time to image the same spot on the surface 11 times over before moving to the next area of interest. The sets of color images will help us learn about the variation in composition from place to place on the planet. For example, some minerals such as olivine and pyroxene often absorb more light at longer wavelengths than at shorter ones, so we’ll be looking for their signatures in the reflectance spectra derived from each eight-color set. WAC images will be used in coordination with the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), a hyperspectral instrument that provides reflectance information at many more wavelengths, but only for one spot on the surface at a time.
A First Look at Terrain Near Mercury's North Pole
This WAC image showing a never-before-imaged area of Mercury’s surface was taken from an altitude of ~450 km (280 miles) above the planet during the spacecraft’s first orbit with the camera in operation. The area is covered in secondary craters made by an impact outside of the field of view. Some of the secondary craters are oriented in chain-like formations.

This image was taken during MESSENGER’s closest approach to the sunlit portion of the surface during this orbit, just before crossing over the terminator. The oblique illumination by the Sun causes the long shadows and accentuates topography. The highly elliptical orbit of MESSENGER brings the spacecraft down to a periapsis (MESSENGER’s closest approach to Mercury) altitude of ~200 km (125 miles) and out to an apoapsis (MESSENGER’s farthest distance from Mercury) altitude of ~15,000 km (9300 miles).
Exploring the Rays of Debussy
Bright rays, consisting of impact ejecta and secondary craters, spread across this NAC image and radiate from Debussy crater, located at the top. The image, acquired yesterday during the first orbit for which MDIS was imaging, shows just a small portion of Debussy's large system of rays in greater detail than ever previously seen. Images acquired during MESSENGER's second Mercury flyby showed that Debussy's rays extend for hundreds of kilometers across Mercury's surface. Debussy crater was named in March 2010, in honor of the French composer Claude Debussy (1862-1918).
Smooth Plains in Mercury's North
As the MESSENGER spacecraft passed low over Mercury's north polar region, MDIS used its pivot to capture this image, showing terrain that had not been previously seen by spacecraft. The newly imaged surface is located in Mercury's north polar region, to the north of the bright, rayed crater Hokusai. Looking from the bottom of the image toward the top is looking southward, just as MDIS was doing when this image was acquired.

This newly seen terrain shows craters with long shadows, as expected at this high northern latitude. Understanding the interiors of the craters in Mercury's polar regions and any ices they may contain is one of the main science goals of the MESSENGER mission. The long shadows also accentuate the topography of the surface, which includes a number of ridges that resemble those seen on the expansive smooth plains imaged during Mercury flyby 3.
Simply Beautiful
The crater near the bottom of this image is a beautiful example of a relatively small, simple, fresh impact feature on Mercury. It illustrates the textbook characteristics of a crater in its size range. The crater is nearly bowl-shaped, with just a small flat area in the center of its floor. The walls and rim are sharp and do not appear to have suffered the collapse and terracing that modify larger craters. The bright ejecta and rays are symmetrically distributed around the crater, indicating that the body that struck Mercury to form the crater approached on a path that was not highly inclined from the vertical.
First NAC Image Obtained in Mercury Orbit
This is the first image of Mercury taken from orbit with MESSENGER’s Narrow Angle Camera (NAC). MESSENGER’s camera system, the Mercury Dual Imaging System (MDIS), has two cameras: the Narrow Angle Camera and the Wide Angle Camera (WAC). Comparison of this image with MESSENGER’s first WAC image of the same region shows the substantial difference between the fields of view of the two cameras. At 1.5°, the field of view of the NAC is seven times smaller than the 10.5° field of view of the WAC.

This image was taken using MDIS’s pivot. MDIS is mounted on a pivoting platform and is the only instrument in MESSENGER’s payload capable of movement independent of the spacecraft. The other instruments are fixed in place, and most point down the spacecraft’s boresight at all times, relying solely on the guidance and control system for pointing. The 90° range of motion of the pivot gives MDIS a much-needed extra degree of freedom, allowing MDIS to image the planet’s surface at times when spacecraft geometry would normally prevent it from doing so. The pivot also gives MDIS additional imaging opportunities by allowing it to view more of the surface than that at which the boresight-aligned instruments are pointed at any given time.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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Re: MESSENGER: First Images from Mercury Orbit

Post by bystander » Thu Mar 31, 2011 11:01 pm

NASA JHU-APL CIW | MESSENGER | 2011 Mar 31

Revisiting Boccaccio
Giovanni Boccaccio was a 14th century Italian poet and novelist. The 142-km-diameter crater at the top of this MESSENGER NAC image was named for Boccaccio after Mariner 10 imaged the region during its second Mercury flyby in 1974. This MESSENGER NAC image reveals the crater under different lighting conditions than at the time of the Mariner 10 flyby. Boccaccio has a prominent central peak, which was formed by uplift from beneath the surficial material at the point of impact.
Debussy Makes a Good Impression
This image shows Debussy crater, named for the impressionist-era French composer Claude Debussy. The impact crater's rim is 80 km in diameter, and the bright crater rays extend for hundreds of kilometers. The object that impacted the surface to form this crater was probably between 4 and 8 km in diameter.

This image was taken with MESSENGER’s Wide Angle Camera (WAC) using the 997-nm filter, one of the 12 filters available for use with the WAC. The WAC is a refracting telescope with a focal length of 78 mm, a field of view of 10.5°, and a collecting area (entrance pupil aperture) of 48 mm2. The detector located on the focal plane is a 1024 × 1024 pixel (1 megapixel) CCD. The filters, which reside on a rotating wheel, range in wavelength from 430 nm to 1040 nm (visible through near-infrared) and include a broadband filter for optical navigation imaging of stars.
Dark Material on Mercury
As the MESSENGER spacecraft moved northward during the first orbit for which images were acquired, the WAC captured this image. The bright rays from Hokusai can be seen extending across this image, but also clearly visible near the center of this image is a small patch of material that is considerably darker than the surrounding terrain. Other locations with dark material have been spotted across Mercury's surface, including the floor of Hemingway crater, as a halo surrounding Derain, as rays from Matabei, and near some craters in Caloris basin. What is this dark material? Likely it is due to a dark type of rock on Mercury's surface, but there is not currently enough information to identify the type of rock. However, with MESSENGER now in orbit, that situation will soon change, as MESSENGER's orbital science campaign will provide unprecedented chemical information about the rock types on Mercury's surface.
Mercury's Colorful Limb
As in this monochrome view of Mercury, the bright rays of Hokusai crater can be seen crossing the surface from north to south. This color image, with the central wavelengths of 1000 nm, 750 nm, and 430 nm displayed in red, green, and blue, respectively, also highlights some of the subtle color variations observed on Mercury. Spectral variations can be due to differences in particle size, duration of time exposed on surface, or composition. The MESSENGER team is working hard to unravel the complicated story contained in these beautiful color images.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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Re: MESSENGER: First Images from Mercury Orbit (more)

Post by bystander » Fri Apr 01, 2011 8:14 pm

NASA JHU-APL CIW | MESSENGER | 2011 Apr 01

Hello, Hodgkins!
The rayed crater near the bottom of this image is Hodgkins, named in July 2009 in honor of the New Zealand painter Frances Hodgkins (1869-1947). In this image, north is approximately toward the upper right corner. Hodgkins has an asymmetric pattern of rays, which provides information about the impact event that formed the crater. Hodgkins' asymmetric rays were formed when an object, traveling in either a northeastern or southwestern direction, struck Mercury at a low angle to the surface. Compare the rays of Hodgkins to the rays of Qi Baishi and Hovnatanian, and read more about low-angle impacts. Visit this image of Bek to learn more about how rays form and how they fade with time.
Two Kinds of Small Craters
This image covers an area of ridged plains to the east of the rim of Hokusai crater on Mercury. The crater's bright rays and ejecta cross the location. The image has higher spatial resolution and a more favorable viewing angle than the coverage of Hokusai from MESSENGER's second flyby and is just one of many images of this impact crater and its environs being collected as part of commissioning activities during MESSENGER's first orbits around Mercury. Here we see chains of small secondary craters that were formed by chunks of debris thrown out of Hokusai during its formation, surrounded by more diffuse high-reflectance rays. A very small, very bright, very fresh (young) primary impact crater and its ejecta blanket light up the top-middle part of the image. North is approximately to the top in this image.
WAC versus NAC
This pair of images illustrates the differences between the footprints of the WAC and the NAC, the two cameras that make up the Mercury Dual Imaging System (MDIS). The image on the left is a WAC image that includes several bright craters. Their bright ejecta patterns indicate that the craters are relatively young. The image on the right is a NAC image taken within the footprint of the WAC image, revealing a complex crater with a central peak (marked by the X). The WAC field of view is approximately seven times wider than that of the NAC. The WAC can image the planet through 11 different color filters. The NAC provides the highest-resolution views of Mercury’s surface.
We've Got the NAC of It
This image of a number of unnamed craters was taken with MESSENGER’s Narrow Angle Camera (NAC), one of the two cameras that make up the Mercury Dual Imaging System (MDIS). The NAC is an off-axis reflector telescope with a focal length of 550 mm, a field of view of 1.5°, and a collecting area of 462 mm2. The detector located on the focal plane is a 1024 × 1024 pixel (1 megapixel) CCD. The NAC takes monochromatic images using a single medium-band filter, unlike the Wide Angle Camera, or WAC, which can view the planet through one of 11 different spectral filters or a broadband filter.

This image was taken using MDIS’s pivot. MDIS is mounted on a pivoting platform and is the only instrument in MESSENGER’s payload capable of movement independent of the spacecraft. The other instruments are fixed in place, and most point down the spacecraft’s boresight at all times, relying solely on the guidance and control system for pointing. The 90° range of motion of the pivot gives MDIS a much-needed extra degree of freedom, allowing MDIS to image the planet’s surface at times when spacecraft geometry would normally prevent it from doing so. The pivot also gives MDIS additional imaging opportunities by allowing it to view more of the surface than just that at which the boresight-aligned instruments are pointed at any given time.
WAC's Changing Footprint
The surface footprint of MESSENGER’s Wide Angle Camera (WAC) changes markedly as the spacecraft moves along its highly elliptical orbit. Here we see an image that includes Mercury's south pole and terminator, viewed from an altitude of ~10,240 km (6363 miles). Approximately half of this image includes portions of Mercury’s surface that are not illuminated by the Sun. Compare the extent of this image to those taken from altitudes of ~450 km (280 miles) and ~14,895 km (9255 miles).
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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Re: MESSENGER: First Images from Mercury Orbit (more)

Post by bystander » Thu Apr 07, 2011 12:21 pm

NASA JHU-APL CIW | MESSENGER | 2011 Apr 04-05

Prime Real Estate | 2011 Apr 04
Image
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Mercury's prime meridian, or 0° longitude, crosses through the left side of this image. The prime meridian was defined as the longitude where the Sun was directly overhead as Mercury passed through its first perihelion in the year 1950. The area was first seen by a spacecraft during MESSENGER's second Mercury flyby and is located to the northwest of the impact crater Derain. The image here has been placed into a map projection with north to the top. The original image was binned on the spacecraft from its original 1024 × 1024 pixel size to 512 × 512. This type of image compression helps to reduce the amount of data that must be downlinked across interplanetary space from MESSENGER to the Deep Space Network on Earth.
A View of Camoes in Mercury's South Polar Region | 2011 Apr 04
Image
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MESSENGER's near-polar orbit about Mercury, in contrast to the mission's three equatorial flybys of the planet, enables MDIS to view Mercury's polar regions for the first time. This image, located in Mercury's south polar region, shows the crater Camoes near the center of the image. A scarp crosses the floor and wall of Camoes, in a pattern similar to that seen at Thakur crater. Camoes takes its name from the Portuguese poet Luiz Vas de Camoes (c. 1524-1580). The crater extending out of the upper left corner of the image is Okyo, named for the Japanese painter Maruyama Okyo (1733-1795).
Polar Express | 2011 Apr 04
Image
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These three images are of Mercury's far-northern "Arctic" region, skirting the 80° N latitude circle, and bring us a glimpse of territory not previously imaged by spacecraft. MESSENGER engineering, instrument, operations, and science teams are checking the performance of the spacecraft and science instruments in the challenging environment in orbit around the planet closest to the Sun. These images and others collected during this "commissioning period" afford an opportunity to test our ability to mosaic overlapping images. These three images were binned on the spacecraft from their original 1024 × 1024 pixel size to 256 × 256. This type of image compression helps to reduce the amount of data that must be downlinked across interplanetary space from MESSENGER to the Deep Space Network on Earth. The images here are not map projected but have been rotated so that north is approximately toward the top.
Equator to Pole (almost) | 2011 Apr 05
Image
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The upper right corner of this image lies at 1° N, just above Mercury's equator, whereas the lower center-left portion is at about 83° S, just 7° from Mercury's south pole. Unusual impact craters Berkel and Derain are seen in the upper right, and the extensive bright ejecta and rays of Debussy dominate much of the middle of the view. The image is not map projected but has north approximately toward the top.
New Territory | 2011 Apr 05
Image
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This image is remarkable for several reasons. First, it was obtained on the first day that the MESSENGER Wide-Angle Camera was operated following the spacecraft's entry into orbit around Mercury. Second, it shows a portion of the surface that has never before been seen by spacecraft (neither by Mariner 10 nor MESSENGER during any of its three flybys). The area of the surface in the image is northeast of Hokusai, a prominent rayed impact crater that was detected in Earth-based radar images before it was imaged by MESSENGER during the second flyby. This image was binned on the spacecraft from its original 1024 × 1024 pixel size to 256 × 256. This type of image compression helps to reduce the amount of data that must be downlinked across interplanetary space from MESSENGER to the Deep Space Network on Earth. The image here has been placed into a map projection with north to the top.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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Re: MESSENGER: First Images from Mercury Orbit (more)

Post by neufer » Thu Apr 07, 2011 6:41 pm

bystander wrote:
Image
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MESSENGER's near-polar orbit about Mercury, in contrast to the mission's three equatorial flybys of the planet, enables MDIS to view Mercury's polar regions for the first time. This image, located in Mercury's south polar region, shows the crater Camoes near the center of the image. A scarp crosses the floor and wall of Camoes, in a pattern similar to that seen at Thakur crater. Camoes takes its name from the Portuguese poet Luiz Vas de Camoes (c. 1524-1580). The crater extending out of the upper left corner of the image is Okyo, named for the Japanese painter Maruyama Okyo (1733-1795).
Art Neuendorffer