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The Secret Lives of Galaxies
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| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
…
| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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The Secret Lives of Galaxies
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| Title |
The Secret Lives of Galaxies Unveiled in Deep Survey |
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Hubble Yields Direct Proof o
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| Title |
Hubble Yields Direct Proof of Stellar Sorting in a Globular Cluster |
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Hubble Yields Direct Proof o
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| Title |
Hubble Yields Direct Proof of Stellar Sorting in a Globular Cluster |
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Hubble Yields Direct Proof o
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| Title |
Hubble Yields Direct Proof of Stellar Sorting in a Globular Cluster |
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Mars Odyssey Science Cover I
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| Title |
Mars Odyssey Science Cover Image |
| Abstract |
This still was created to for the cover of the journal Science (5 July 2002 issue). It shows epithermal neutron data represented by the colors overlayed on Mars topography. The blue colors represent high concentrations of hydrogen, indicating the strong possibility that water ice exists in those regions. The vertical exaggeration is 5x normal and the shading exaggeration is 50x normal. |
| Completed |
2002-06-19 |
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Reull Vallis Source Region
PIA03840
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Reull Vallis Source Region |
| Original Caption Released with Image |
(Released 1 July 2002) The jumbled, chaotic terrain in this THEMIS image may represent a source region for the Reull Vallis, one of the larger channel systems in the southern hemisphere of Mars. Such regions of chaos are thought to form by the catastrophic release of groundwater. If this was the case, then the water would have flowed down gradient to the south and may have contributed to the formation of the Reull Vallis. The top of the image shows two short segments of channels that are interrupted by the chaos, demonstrating that there was a channel system in place before the ground foundered to produce the chaos. One of the more intriguing features seen among the jumbled blocks are narrow ledges that vaguely resemble bath tub rings in the way they conform to the topography. Two good examples are seen running roughly left-right across the image about a fourth of the way down. At first they appear to be layers protruding from the cliff faces, but upon closer inspection a more ledge-like character is evident. Note how they appear different between the south-facing and north facing cliffs. The occurrence of one of these features on the south-facing interior rim of the largest crater in the image but nowhere else around the rim argues against the idea that the ledges are due to a layer of rock cropping out throughout the landscape. Instead, they appear more like the edges of a layer of sediment that drapes the topography. It is possible that the sediment is mixed with ice and is best preserved in the shadowed portions of the terrain. There is no easy explanation for these unusual features. They represent one more Martian enigma. |
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Reull Vallis Source Region
PIA03840
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Reull Vallis Source Region |
| Original Caption Released with Image |
(Released 1 July 2002) The jumbled, chaotic terrain in this THEMIS image may represent a source region for the Reull Vallis, one of the larger channel systems in the southern hemisphere of Mars. Such regions of chaos are thought to form by the catastrophic release of groundwater. If this was the case, then the water would have flowed down gradient to the south and may have contributed to the formation of the Reull Vallis. The top of the image shows two short segments of channels that are interrupted by the chaos, demonstrating that there was a channel system in place before the ground foundered to produce the chaos. One of the more intriguing features seen among the jumbled blocks are narrow ledges that vaguely resemble bath tub rings in the way they conform to the topography. Two good examples are seen running roughly left-right across the image about a fourth of the way down. At first they appear to be layers protruding from the cliff faces, but upon closer inspection a more ledge-like character is evident. Note how they appear different between the south-facing and north facing cliffs. The occurrence of one of these features on the south-facing interior rim of the largest crater in the image but nowhere else around the rim argues against the idea that the ledges are due to a layer of rock cropping out throughout the landscape. Instead, they appear more like the edges of a layer of sediment that drapes the topography. It is possible that the sediment is mixed with ice and is best preserved in the shadowed portions of the terrain. There is no easy explanation for these unusual features. They represent one more Martian enigma. |
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Amazonis Planitia
PIA03843
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Amazonis Planitia |
| Original Caption Released with Image |
(Released 5 July 2002) This is an image of a crater within part of Amazonis Planitia, located at 22.9N, 152.5W. This image features a number of common features exhibited by Martian craters. The crater is sufficiently large to exhibit a central peak that is seen in the upper right hand corner if the image. Also apparent is the slump blocks on the inside of the crater walls. When the crater was first formed, the crater walls were unstable and subsequently formed a series of landslides over time that formed the hummocky terrain just inside the present crater wall. While these cratering features are common to craters formed on other planetary bodies, such as the moon, the ejecta blanket surrounding the crater displays a morphology that is more unique to Mars. The lobate morphology implies that the ejecta blanket was emplaced in an almost fluid fashion rather than the traditional ballistic ejecta emplacement. This crater morphology occurs on Mars where water ice is suspected to be present just beneath the surface. The impact that created the crater would have enough energy to melt large amounts of water that could form the mud or debris flows that characterize the ejecta morphology that is seen in this image. |
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Amazonis Planitia
PIA03843
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Amazonis Planitia |
| Original Caption Released with Image |
(Released 5 July 2002) This is an image of a crater within part of Amazonis Planitia, located at 22.9N, 152.5W. This image features a number of common features exhibited by Martian craters. The crater is sufficiently large to exhibit a central peak that is seen in the upper right hand corner if the image. Also apparent is the slump blocks on the inside of the crater walls. When the crater was first formed, the crater walls were unstable and subsequently formed a series of landslides over time that formed the hummocky terrain just inside the present crater wall. While these cratering features are common to craters formed on other planetary bodies, such as the moon, the ejecta blanket surrounding the crater displays a morphology that is more unique to Mars. The lobate morphology implies that the ejecta blanket was emplaced in an almost fluid fashion rather than the traditional ballistic ejecta emplacement. This crater morphology occurs on Mars where water ice is suspected to be present just beneath the surface. The impact that created the crater would have enough energy to melt large amounts of water that could form the mud or debris flows that characterize the ejecta morphology that is seen in this image. |
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Hephaestus Fossae
PIA03842
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Hephaestus Fossae |
| Original Caption Released with Image |
(Released 3 July 2002) Off the western flank of Elysium are the Hephaestus Fossae, including linear arrangements of small, round pits. These features are commonly called "pit chains" and most likely represent the collapse of lava tubes. Lava tubes allow molten rock to move long distances underground. When the lava drains out it leaves unsupported tunnels, which can collapse and form pits. These particular pit chains are unusual because they change direction abruptly. In the lower portion of the image, pits have collapsed at the bends and allow us to observe the sharp, nearly right angle corners. These direction changes are most likely due to some sort of structural control during the emplacement of the lava tubes. There is an extraordinarily high concentration of small, degraded craters on the plains surface. The size range of these craters is fairly consistent and they all appear to be of similar age. It is unlikely that these were caused by primary impacts (impacts of meteors onto the surface) because both the size and timing distributions of primary impactors vary tremendously. However, the craters in the image could have been created from secondary impacts. Secondaries are impacts of material that is excavated during a large cratering event nearby or from the disintegration of a primary meteor in the atmosphere into many smaller parts that rain onto the surface. In contrast to these older, small craters, there is a relatively young crater in the center of the image. A hummocky ejecta blanket is visible around the crater and has covered some of the smaller craters on the plain around it. The edges of the crater are sharp, formed by rocky material in the crater rim. This material is visible as the layer of rough, grooved material at the top of the inside walls. Small dust avalanches have left dark streaks down the inside walls of the crater. |
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Hephaestus Fossae
PIA03842
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Hephaestus Fossae |
| Original Caption Released with Image |
(Released 3 July 2002) Off the western flank of Elysium are the Hephaestus Fossae, including linear arrangements of small, round pits. These features are commonly called "pit chains" and most likely represent the collapse of lava tubes. Lava tubes allow molten rock to move long distances underground. When the lava drains out it leaves unsupported tunnels, which can collapse and form pits. These particular pit chains are unusual because they change direction abruptly. In the lower portion of the image, pits have collapsed at the bends and allow us to observe the sharp, nearly right angle corners. These direction changes are most likely due to some sort of structural control during the emplacement of the lava tubes. There is an extraordinarily high concentration of small, degraded craters on the plains surface. The size range of these craters is fairly consistent and they all appear to be of similar age. It is unlikely that these were caused by primary impacts (impacts of meteors onto the surface) because both the size and timing distributions of primary impactors vary tremendously. However, the craters in the image could have been created from secondary impacts. Secondaries are impacts of material that is excavated during a large cratering event nearby or from the disintegration of a primary meteor in the atmosphere into many smaller parts that rain onto the surface. In contrast to these older, small craters, there is a relatively young crater in the center of the image. A hummocky ejecta blanket is visible around the crater and has covered some of the smaller craters on the plain around it. The edges of the crater are sharp, formed by rocky material in the crater rim. This material is visible as the layer of rough, grooved material at the top of the inside walls. Small dust avalanches have left dark streaks down the inside walls of the crater. |
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Deuteronilus Mensae
PIA03844
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Deuteronilus Mensae |
| Original Caption Released with Image |
(Released 8 July 2002) This THEMIS visible image shows several "fretted" channels within Deuteronilus Mensae in the northern plains of Mars. These linear troughs appear to have been extensively modified by surficial processes. Their floors contain knobby or "scabby" materials that have been modified to produce a pitted, knobby surface. This type of surface is common in the northern highlands of Mars, and its location and pitted texture has been suggested to indicate that these materials once contained ice that has since been removed to form the pits (devolatization). Many of the sloping surfaces in this region image have unusual deposits of material that occur preferentially on the cold, north-facing slopes. These deposits are seen frequently at mid-northern and southern latitudes, and have a distinct, rounded boundary that typically occurs at approximately the same distance below the ridge crest. It has been suggested that these deposits once draped the entire surface and have since been removed from all but the north-facing slopes. In some regions these deposits have ridges that parallel the cliff, suggestive of downslope movement and compression, possibly aided by ice. In some areas these slope deposits are darker than the material on the floor of the channel, and appear to sit on top of the pitted channel-floor materials. This relationship indicates that the slope materials have slightly different properties, leading to their darker tone, and are younger (and thus on top of) the channel floors. The presence of water ice in the surface in this area is a likely possibility to account for many of the features observed. This ice may still be present near the surface and this region may still be undergoing modification today. |
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Deuteronilus Mensae
PIA03844
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Deuteronilus Mensae |
| Original Caption Released with Image |
(Released 8 July 2002) This THEMIS visible image shows several "fretted" channels within Deuteronilus Mensae in the northern plains of Mars. These linear troughs appear to have been extensively modified by surficial processes. Their floors contain knobby or "scabby" materials that have been modified to produce a pitted, knobby surface. This type of surface is common in the northern highlands of Mars, and its location and pitted texture has been suggested to indicate that these materials once contained ice that has since been removed to form the pits (devolatization). Many of the sloping surfaces in this region image have unusual deposits of material that occur preferentially on the cold, north-facing slopes. These deposits are seen frequently at mid-northern and southern latitudes, and have a distinct, rounded boundary that typically occurs at approximately the same distance below the ridge crest. It has been suggested that these deposits once draped the entire surface and have since been removed from all but the north-facing slopes. In some regions these deposits have ridges that parallel the cliff, suggestive of downslope movement and compression, possibly aided by ice. In some areas these slope deposits are darker than the material on the floor of the channel, and appear to sit on top of the pitted channel-floor materials. This relationship indicates that the slope materials have slightly different properties, leading to their darker tone, and are younger (and thus on top of) the channel floors. The presence of water ice in the surface in this area is a likely possibility to account for many of the features observed. This ice may still be present near the surface and this region may still be undergoing modification today. |
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Ismenia Fossae
PIA03841
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Ismenia Fossae |
| Original Caption Released with Image |
(Released 2 July 2002) This THEMIS image is in a region of Mars' northern hemisphere called Ismenia Fossae. Most of the landforms in this image are the degraded remains of impact crater rim and ejecta from an unnamed crater (75 km diameter) just north of this scene (refer to the context image). The terminus of this ejecta blanket can be seen in the lower third of the image. The hills and other topographic highs of this landscape appear to be mantled. This mantling layer has itself been modified to produce a pitted, knobby surface in places. The presence of water ice in the mantling material is a likely possibility. Also visible in this image are some small degraded craters located primarily in the upper half of this scene. |
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Ismenia Fossae
PIA03841
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Ismenia Fossae |
| Original Caption Released with Image |
(Released 2 July 2002) This THEMIS image is in a region of Mars' northern hemisphere called Ismenia Fossae. Most of the landforms in this image are the degraded remains of impact crater rim and ejecta from an unnamed crater (75 km diameter) just north of this scene (refer to the context image). The terminus of this ejecta blanket can be seen in the lower third of the image. The hills and other topographic highs of this landscape appear to be mantled. This mantling layer has itself been modified to produce a pitted, knobby surface in places. The presence of water ice in the mantling material is a likely possibility. Also visible in this image are some small degraded craters located primarily in the upper half of this scene. |
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