The new Mars crater spans half the length of a
football field in this photo from the Mars Reconnaissance Orbiter’s
sharpest-sighted camera, the High Resolution Imaging Science
Experiment.
Image Credit:
NASA/JPL-Caltech/University of
Arizona
Feature Link:
Researchers have discovered on
the Red Planet the largest fresh meteor-impact crater ever firmly documented
with before-and-after images. The images were captured by NASA's Mars
Reconnaissance Orbiter (MRO).
The crater spans half the length of a football field and first appeared in
March 2012. The impact that created it likely was preceded by an explosion in
the Martian sky caused by intense friction between an incoming asteroid and the
planet's atmosphere. This series of events can be likened to the meteor blast
that shattered windows in Chelyabinsk, Russia, last year. The air burst and
ground impact darkened an area of the Martian surface about 5 miles (8
kilometers) across.
Scientists using NASA's Mars Reconnaissance Orbiter
found a fresh meteor-impact crater, and by golly it's big. It's the largest ever
located anywhere by using before-and-after pictures.
The darkened spot appears in images taken by the orbiter's weather-monitoring
camera, the Mars Color Imager (MARCI). Images of the site from MARCI and from
the two telescopic cameras on MRO are at:
Since the orbiter began its systematic observation of Mars in 2006, scientist
Bruce Cantor has examined MARCI's daily global coverage, looking for evidence of
dust storms and other observable weather events in the images. Cantor is this
camera's deputy principal investigator at Malin Space Science Systems, the San
Diego company that built and operates MARCI and the orbiter's telescopic Context
Camera (CTX). Through his careful review of the images, he helps operators of
NASA's solar-powered Mars rover, Opportunity, plan for weather events that may
diminish the rover's energy. He also posts weekly Mars weather reports.
About two months ago, Cantor noticed an inconspicuous dark dot near the
equator in one of the images.
"It wasn't what I was looking for," Cantor said. "I was doing my usual
weather monitoring and something caught my eye. It looked usual, with rays
emanating from a central spot."
This April 6, 2014, image from the High Resolution
Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter
shows numerous landslides in the vicinity of where an impact crater was
excavated in March 2012.
Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Feature Link:
These two images taken one day apart by the MARCI
weather camera on NASA's Mars Reconnaissance Orbiter reveal when an asteroid
impact made the scar seen in the right-hand image. The left image was taken
during Martian afternoon on March 27, 2012; the right one on the afternoon of
March 28, 2012.
Image Credit: NASA/JPL-Caltech/MSSS
Feature Link:
He began examining earlier
images, skipping back a month or more at a time. The images revealed that the
dark spot was present a year ago, but not five years ago. He homed in further,
checking images from about 40 different dates, and pinned down the date the
impact event occurred; the spot was not there up through March 27, 2012, and
then appeared before the daily imaging on March 28, 2012.
Once the dark spot was verified as new, it was targeted last month by CTX and
the orbiter's sharpest-sighted camera, the High Resolution Imaging Science
Experiment (HiRISE). Of the approximately 400 fresh crater-causing impacts on
Mars that have been documented with before-and-after images, this is the only
one discovered using a MARCI image, rather than an image from a
higher-resolution camera.
CTX has imaged nearly the entire surface of Mars at least once during the
orbiter's seven-plus years of observations. It had photographed the site of this
newly-discovered crater in January 2012, prior to the impact. Two craters appear
in the April 2014 CTX image that were not present in the earlier one,
confirming the dark spot revealed by MARCI is related to a new impact
crater.
HiRISE reveals more than a dozen smaller craters near the two larger ones
seen in the CTX image, possibly created by chunks of the exploding asteroid or
secondary impacts of material ejected from the main craters during impact. It
also reveals many landslides that darkened slopes in the 5-mile surrounding
area. A second HiRISE image in May 2014 added three-dimensional information.
"The biggest crater is unusual, quite shallow compared to other fresh craters
we have observed," said HiRISE Principal Investigator Alfred McEwen of the
University of Arizona, Tucson.
The largest crater is slightly elongated and spans 159 by 143 feet (48.5 by
43.5 meters).
McEwen estimates the impact object measured about 10 to 18 feet (3 to 5
meters) long, which is less than a third the estimated length of the asteroid
that hit Earth's atmosphere near Chelyabinsk. Because Mars has much less
atmosphere than Earth, space rocks of comparable size are more likely to
penetrate to the surface of Mars and cause larger craters.
"Studies of fresh impact craters on Mars yield valuable information about
impact rates and about subsurface material exposed by the excavations," said
Leslie Tamppari, deputy project scientist for the Mars Reconnaissance Orbiter
mission at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "The
combination of HiRISE and CTX has found and examined many of them, and now
MARCI's daily coverage has given great precision about when a significant impact
occurred."
NASA is developing concepts for its asteroid initiative to redirect a
near-Earth asteroid -- possibly about the size of the rock that hit Mars on
March 27 or 28, 2012 -- but much closer to Earth's distance from the sun. The
project would involve a solar-powered spacecraft capturing a small asteroid or
removing a piece of a larger asteroid, and redirecting it into a stable orbit
around Earth's moon.
Astronauts will travel to the asteroid aboard NASA's Orion spacecraft,
launched on the agency's Space Launch System rocket, to rendezvous with the
captured asteroid. Once there, they would collect samples to return to Earth for
study. This experience in human spaceflight beyond low-Earth orbit will help
NASA test new systems and capabilities needed to send astronauts to Mars in the
2030s.
Malin Space Science Systems, San Diego, built and operates MARCI and CTX. The
University of Arizona, Tucson, operates HiRISE, which was built by Ball
Aerospace & Technologies Corp. of Boulder, Colorado. JPL, a division of the
California Institute of Technology, Pasadena, manages the Mars Reconnaissance
Orbiter Project for NASA's Science Mission Directorate, Washington. Lockheed
Martin Space Systems, Denver, built the spacecraft and collaborates with JPL to
operate it.
For more information about the Mars Reconnaissance Orbiter and its findings,
visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
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