NASA MESSENGER Prepares For Impact On Mercury
NASA's MESSENGER spacecraft is beaming back some final, incredible photos as it prepares to smash into the planet's surface -- a hard landing for the first spacecraft to orbit Mercury.
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The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), mission is a NASA-sponsored scientific investigation of the planet Mercury and represents the agency's first space mission designed to orbit the planet closest to the Sun.
Launched on Aug. 3, 2004, MESSENGER entered orbit around Mercury on March 18, 2011 to begin a year-long study of its target planet, and is now on its second extended mission.
That mission will end when it collides into Mercury at a speed of more than 8,750 miles per hour sometime on Thursday, April 30, as the spacecraft runs out of propellant and the force of solar gravity causes it to impact the surface of the planet.
The Mercury Atmosphere and Surface Composition Spectrometer (MASCS) instrument aboard the spacecraft was designed to study both the exosphere and surface of the planet Mercury. In the mission's more than four years of orbital operations, Messenger acquired more than 250,000 images and other extensive data sets.
In a briefing at NASA headquarters earlier this month, the mission's scientists and engineers ticked off the top science findings and technological innovations from the mission, such as having provided compelling support for the hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters.
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"MESSENGER had to survive heating from the Sun, heating from the dayside of Mercury, and the harsh radiation environment in the inner heliosphere, and the clearest demonstration that our innovative engineers were up to the task has been the spacecraft's longevity in one of the toughest neighborhoods in our Solar System," MESSENGER principal investigator Sean Solomon, director of Columbia University's Lamont-Doherty Earth Observatory, said in a statement. "Moreover, all of the instruments that we selected nearly two decades ago have proven their worth and have yielded an amazing series of discoveries about the innermost planet."
In honor of MESSENGER's spectacular successes and the mission's equally spectacular denouement, we've assembled a selection of images highlighting the fascinating findings beamed back to planet earth.
This photo was taken in October 2013 with the spacecraft's Wide Angle Camera (WAC) and shows the planet's asteroid battered surface. Near the center of the image rests an impact crater 75 miles across, which is surrounded by chains of secondary craters. In 2012, NASA confirmed that images from MESSENGER had detected craters at the north pole containing water ice.
While it's hard to study solar flares from back here on Earth, the MESSENGER mission gave NASA scientists a front-row seat in detecting what they consist of. MESSENGER didn't snap this shot -- that credit goes to a solar telescope on the agency's Solar Terrestrial Relations Observatory (STEREO) spacecraft. MESSENGER's proximity to the sun let it detect solar neutrons that are created in solar flares, helping scientists better understand the flares' makeup.
On the mission's first flyby in 2008, MESSENGER snapped this portrait of the planet not previously seen by spacecraft. While color differences on the planet are subtle, they reveal important information about the nature of the Mercury's surface material. For instance, the numerous bright spots with a bluish tinge are relatively recent impact craters.
MESSENGER's Mercury Laser Altimeter (MLA) instrument was deployed to map the topography of Mercury's northern hemisphere in great detail. The lowest regions are shown in purple and the highest regions are shown in red, with a difference of about six miles between the two. The low-lying craters near the north pole host radar-bright materials, thought to be water ice.
As measured by the MLA instrument, and surface-mapped by the MDIS instrument, this recent image shows the terrain around the center portion of Carnegie Rupes, a large tectonic landform that cuts through Duccio crater. These landforms occur on Mercury in response to interior planetary cooling, which results in the overall shrinking of the planet.
This orthographic projection -- a means of representing a three-dimensional object in two dimensions -- provides a look at the planet's northern polar region. The yellow regions in many of the craters mark locations that show evidence of water ice. MESSENGER also provided images from within the permanently shaded interiors of some of the craters.
This close-up view of the Stevenson Crater, also known as Crater X, is defined by the prominent diagonal secondary crater chains caused by ejecta, caused by two impacts located outside of the field of view. The massive crater is 83 miles in diameter. This photo shows just 50 miles of the crater's floor.
You're forgiven for not recognizing where we live, especially from 61 million miles away, but those two overexposed points of light -- each less than a pixel in size -- are the earth and the moon, as taken by MESSENGER in 2013. The image was captured on the same day that images of the earth from an even greater distance (nearly 900 million miles, if you're counting) were taken by the Cassini spacecraft near the Saturn system.
You're forgiven for not recognizing where we live, especially from 61 million miles away, but those two overexposed points of light -- each less than a pixel in size -- are the earth and the moon, as taken by MESSENGER in 2013. The image was captured on the same day that images of the earth from an even greater distance (nearly 900 million miles, if you're counting) were taken by the Cassini spacecraft near the Saturn system.
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