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Collection:
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NASA Planetary Photo Journal Collection
Collection
NASA Planetary Photo Journal Collection
Collection
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Title:
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NIMS Observes Melkart Crater on Ganymede
Title
NIMS Observes Melkart Crater on Ganymede
Title
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Original Caption Released with Image:
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The top figure is an image of the crater Melkart on Ganymede, at a wavelength of 0.85 microns, taken by the Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft, The crater is illuminated by the Sun from the left. The finest detail that can be seen is approximately 30 km in size. What is most obvious, and of great interest, are the two concentric ring structures and the central dome. The walls of these rings are in shadow on the left, and are in sunlight on the right. To understand how these rings and central dome are thought to form, consider a pebble dropped into a pond. Ripples spread out from the center, oscillating up and down. The rings and dome forming Melkart are a snapshot of these ripples in the ice of Ganymede, possibly caused by the impact of a comet or asteroid. Similar features on the Moon are only associated with much larger craters as the stronger Moon rock behaves this way only with large impacts. NIMS can obtain images at many different wavelengths from 0.7 to 5.2 microns. The spectrum shows the amount of reflected light as a function of wavelength from the crater floor of Melkart. Several distinct absorption features, caused by water ice, are evident at 1.5 and 2.0 microns. Beyond 3.0 microns the intensity increases again as the longer wavelengths are more sensitive to Ganymede's thermal radiation. The shape of the absorption features suggest that the ice is mixed with hydrated minerals. These relatively dark minerals probably cause the variations in ice brightness seen at visible wavelengths. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa…galileo.
Original_Caption_Rel eased_with_Image
The top figure is an image of the crater Melkart on Ganymede, at a wavelength of 0.85 microns, taken by the Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft, The crater is illuminated by the Sun from the left. The finest detail that can be seen is approximately 30 km in size. What is most obvious, and of great interest, are the two concentric ring structures and the central dome. The walls of these rings are in shadow on the left, and are in sunlight on the right. To understand how these rings and central dome are thought to form, consider a pebble dropped into a pond. Ripples spread out from the center, oscillating up and down. The rings and dome forming Melkart are a snapshot of these ripples in the ice of Ganymede, possibly caused by the impact of a comet or asteroid. Similar features on the Moon are only associated with much larger craters as the stronger Moon rock behaves this way only with large impacts. NIMS can obtain images at many different wavelengths from 0.7 to 5.2 microns. The spectrum shows the amount of reflected light as a function of wavelength from the crater floor of Melkart. Several distinct absorption features, caused by water ice, are evident at 1.5 and 2.0 microns. Beyond 3.0 microns the intensity increases again as the longer wavelengths are more sensitive to Ganymede's thermal radiation. The shape of the absorption features suggest that the ice is mixed with hydrated minerals. These relatively dark minerals probably cause the variations in ice brightness seen at visible wavelengths. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa…galileo. Original Caption Released with Image
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Addition Date:
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1998-03-26
Addition_Date
1998-03-26
Addition Date
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Produced By:
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JPL
Produced_By
JPL
Produced By
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Mission:
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Galileo
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Spacecraft:
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Galileo Orbiter
Spacecraft
Galileo Orbiter
Spacecraft
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Target Name:
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Ganymede
Target_Name
Ganymede
Target Name
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Is a satellite of:
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Jupiter
Is_a_satellite_of
Jupiter
Is a satellite of
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Instrument:
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Near Infrared Mapping Spectrometer
Instrument
Near Infrared Mapping Spectrometer
Instrument
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Product Size:
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445 samples x 525 lines
Product_Size
445 samples x 525 lines
Product Size
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Primary Data Set:
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Galileo EDRs
Primary_Data_Set
Galileo EDRs
Primary Data Set
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Producer ID:
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P49172A
MRPS82762
Producer_ID
P49172A
MRPS82762
Producer ID
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facet_what:
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Sun
facet_what
Sun
facet_what
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facet_what:
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Crater
facet_what
Crater
facet_what
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facet_what:
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Moon
facet_what
Moon
facet_what
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facet_what:
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Jupiter
facet_what
Jupiter
facet_what
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facet_what:
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Galileo
facet_what
Galileo
facet_what
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facet_what:
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Galileo Orbiter
facet_what
Galileo Orbiter
facet_what
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facet_what:
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Spectrometer
facet_what
Spectrometer
facet_what
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facet_what:
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Ganymede
facet_what
Ganymede
facet_what
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facet_what:
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Snapshot
facet_what
Snapshot
facet_what
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facet_what:
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Near Infrared Mapping Spectrometer (NIMS)
facet_what
Near Infrared Mapping Spectrometer (NIMS)
facet_what
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facet_what:
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Ganymede (Jupiter Moon)
facet_what
Ganymede (Jupiter Moon)
facet_what
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facet_where:
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Jet Propulsion Laboratory
facet_where
Jet Propulsion Laboratory
facet_where
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facet_where:
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Jupiter
facet_where
Jupiter
facet_where
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facet_where:
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Washington
facet_where
Washington
facet_where
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facet_where:
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Ganymede
facet_where
Ganymede
facet_where
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facet_where:
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Jet Propulsion Laboratory (JPL)
facet_where
Jet Propulsion Laboratory (JPL)
facet_where
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Image #:
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PIA00878
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UID:
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SPD-PHOTJ-PIA00878
UID
SPD-PHOTJ-PIA00878
UID
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orignial url:
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orignial_url
orignial url
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