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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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Recently-Formed Impact Crater
Title
Recently-Formed Impact Crater
Title
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Original Caption Released with Image:
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Scientists using the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft have discovered a crater that appears to have formed on Mars in the past 20 or so Earth years, and have used it and several other similar craters to estimate the present cratering rate on Mars.
One of the basic tenets of planetary geology is that impact craters have accumulated on planetary surfaces at roughly a constant rate since the early history of the solar system. This appears to have been the case for small craters on the surface of the Moon, as shown by measurements of the length of time that lunar rocks created by small impacts have been exposed to cosmic rays, as determined by laboratory measurements of samples returned to Earth by the Apollo astronauts. This principle should permit the number of craters found on a planetary surface to be used to determine the age of that surface, if the rate at which new craters form is known.
Scientists have previously estimated the cratering rate of Mars by scaling the lunar cratering rate based on the proximity of Mars to the asteroid belt, and by performing calculations based on orbital mechanics. Another way to establish the cratering rate of Mars would be to use long-term observations, say, from orbiting spacecraft, to actually locate new craters.
The new crater is located on the southern rim of the summit crater, or caldera, of the intermediate-sized martian volcano, Ulysses Patera. The site was imaged by the Viking 2 orbiter in 1976 (left, an enlarged portion of the image) and in narrow-angle views by the Mars Orbiter Camera in 1999 (center) and 2005 (right). The new crater, about 25 meters (82 feet) across, is marked by a distinct dark, rayed pattern of ejected material, or ejecta, which is seen to have faded somewhat between 1999 and 2005.
Ulysses Patera, a volcanic shield about 100 kilometers (62 miles) in diameter volcanic shield, located near 2.5 degrees north latitude, 121.3 degrees west longitude, is one of the Tharsis volcanoes and is partly buried by younger lava flows. The summit caldera is about 55 kilometers (34 miles) in diameter.
The amount that the crater's rays faded between 1999 and 2005 can be used to help estimate how many years ago the crater formed. The actual contrast between the ejecta and the undisturbed volcano summit materials is actually much less than it appears to be in these processed images, and the amount of fading is also much less. Images of disturbed surfaces from various parts of Mars, such as dust devil tracks, dark slope streaks and rover tracks, indicate that disturbed surfaces on Mars are dark and that they lighten with time. Using these other examples to estimate how dark the ejecta from the Ulysses crater was originally, and how much it has faded in six years, suggests the crater formed in the early to mid 1980s.
The rate at which dark surfaces lighten on Mars is not uniform over the whole planet, but scientists using the Mars Orbiter Camera have found a
Original_Caption_Rel eased_with_Image
Scientists using the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft have discovered a crater that appears to have formed on Mars in the past 20 or so Earth years, and have used it and several other similar craters to estimate the present cratering rate on Mars.
One of the basic tenets of planetary geology is that impact craters have accumulated on planetary surfaces at roughly a constant rate since the early history of the solar system. This appears to have been the case for small craters on the surface of the Moon, as shown by measurements of the length of time that lunar rocks created by small impacts have been exposed to cosmic rays, as determined by laboratory measurements of samples returned to Earth by the Apollo astronauts. This principle should permit the number of craters found on a planetary surface to be used to determine the age of that surface, if the rate at which new craters form is known.
Scientists have previously estimated the cratering rate of Mars by scaling the lunar cratering rate based on the proximity of Mars to the asteroid belt, and by performing calculations based on orbital mechanics. Another way to establish the cratering rate of Mars would be to use long-term observations, say, from orbiting spacecraft, to actually locate new craters.
The new crater is located on the southern rim of the summit crater, or caldera, of the intermediate-sized martian volcano, Ulysses Patera. The site was imaged by the Viking 2 orbiter in 1976 (left, an enlarged portion of the image) and in narrow-angle views by the Mars Orbiter Camera in 1999 (center) and 2005 (right). The new crater, about 25 meters (82 feet) across, is marked by a distinct dark, rayed pattern of ejected material, or ejecta, which is seen to have faded somewhat between 1999 and 2005.
Ulysses Patera, a volcanic shield about 100 kilometers (62 miles) in diameter volcanic shield, located near 2.5 degrees north latitude, 121.3 degrees west longitude, is one of the Tharsis volcanoes and is partly buried by younger lava flows. The summit caldera is about 55 kilometers (34 miles) in diameter.
The amount that the crater's rays faded between 1999 and 2005 can be used to help estimate how many years ago the crater formed. The actual contrast between the ejecta and the undisturbed volcano summit materials is actually much less than it appears to be in these processed images, and the amount of fading is also much less. Images of disturbed surfaces from various parts of Mars, such as dust devil tracks, dark slope streaks and rover tracks, indicate that disturbed surfaces on Mars are dark and that they lighten with time. Using these other examples to estimate how dark the ejecta from the Ulysses crater was originally, and how much it has faded in six years, suggests the crater formed in the early to mid 1980s.
The rate at which dark surfaces lighten on Mars is not uniform over the whole planet, but scientists using the Mars Orbiter Camera have found a
Original Caption Released with Image
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Original Caption Released with Image:
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number of other craters with dark ejecta that have faded during the Mars Global Surveyor mission. The scientists estimate that these craters probably formed within the past 100 years. Although the sample is very small (the Mars Orbiter Camera narrow angle camera has imaged barely 4 percent of Mars), it appears that the recent cratering rate for craters on Mars 25 to 100 meters (82 to 328 feet) in diameter is about 0.000000003 to 0.000000006 craters per square kilometer (0.39 square mile) per Earth year, which is about five times lower than previous estimates.
The site of the new crater is shown in wider context in a comparison of the 1976 Viking image with wide-angle views taken by the Mars Orbiter Camera in 1999 and 2005 (figure 2), and in even wider context in a regional mosaic of Viking images (figure 3).
The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington.
Original_Caption_Rel eased_with_Image
number of other craters with dark ejecta that have faded during the Mars Global Surveyor mission. The scientists estimate that these craters probably formed within the past 100 years. Although the sample is very small (the Mars Orbiter Camera narrow angle camera has imaged barely 4 percent of Mars), it appears that the recent cratering rate for craters on Mars 25 to 100 meters (82 to 328 feet) in diameter is about 0.000000003 to 0.000000006 craters per square kilometer (0.39 square mile) per Earth year, which is about five times lower than previous estimates.
The site of the new crater is shown in wider context in a comparison of the 1976 Viking image with wide-angle views taken by the Mars Orbiter Camera in 1999 and 2005 (figure 2), and in even wider context in a regional mosaic of Viking images (figure 3).
The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington.
Original Caption Released with Image
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Image Credit:
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NASA/JPL/MSSS
Image_Credit
NASA/JPL/MSSS
Image Credit
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Produced By:
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Malin Space Science Systems
Produced_By
Malin Space Science Systems
Produced By
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Mission:
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Mars Global Surveyor (MGS)
Mission
Mars Global Surveyor (MGS)
Mission
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Spacecraft:
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Mars Global Surveyor Orbiter
Spacecraft
Mars Global Surveyor Orbiter
Spacecraft
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Target Name:
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Mars
Target_Name
Mars
Target Name
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Is a satellite of:
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Sol (our sun)
Is_a_satellite_of
Sol (our sun)
Is a satellite of
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Instrument:
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Mars Orbiter Camera
Instrument
Mars Orbiter Camera
Instrument
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Product Size:
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2531 samples x 1529 lines
Product_Size
2531 samples x 1529 lines
Product Size
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Producer ID:
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MOC2-1221
Producer_ID
MOC2-1221
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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Earth
facet_what
Earth
facet_what
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facet_what:
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Mars
facet_what
Mars
facet_what
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facet_what:
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Viking
facet_what
Viking
facet_what
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facet_what:
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Surveyor
facet_what
Surveyor
facet_what
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facet_what:
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Viking 2 Orbiter
facet_what
Viking 2 Orbiter
facet_what
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facet_what:
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Ulysses
facet_what
Ulysses
facet_what
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facet_what:
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Mars Global Surveyor Orbiter (MGS)
facet_what
Mars Global Surveyor Orbiter (MGS)
facet_what
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facet_what:
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Mars Orbiter Camera (MOC)
facet_what
Mars Orbiter Camera (MOC)
facet_what
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facet_where:
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Mars
facet_where
Mars
facet_where
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facet_where:
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California
facet_where
California
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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Jet Propulsion Laboratory (JPL)
facet_where
Jet Propulsion Laboratory (JPL)
facet_where
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facet_when:
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1976
facet_when
1976
facet_when
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facet_when:
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1999
facet_when
1999
facet_when
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facet_when_year:
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1999
facet_when_year
1999
facet_when_year
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facet_when_year:
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1976
facet_when_year
1976
facet_when_year
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Image #:
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PIA04292
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UID:
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SPD-PHOTJ-PIA04292
UID
SPD-PHOTJ-PIA04292
UID
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orignial url:
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orignial_url
orignial url
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