NASA probe shoots 3D images of potato-shaped moon Phobos
The heavily cratered Phobos, which is 13.7 miles (22-kilometer) in diameter, is thought by scientists to be an asteroid previously captured by the gravitational pull of the planet Mars.
It is the larger and closer of Mars’ two moons (with the other one named Deimos). As the closest moon to any planet, Phobos is only 5,823 miles (9,377 kilometers) from the surface of Mars.
The tiny moon of Mars was photographed twice by HiRISE on March 23, 2008, while the MRO spacecraft was only 4,290 miles (6,800 kilometers) and 3,600 miles (5,800 kilometers) from the surface of Phobos.
The images are in three-dimensions because the camera has the ability to take images at three different wavelengths of visible light and infrared light and is able to take images at slightly different angles. These images were then combined by NASA scientists.
In the two images, the large impact crater Stickney dominates the scenery. The crater is approximately 5.6 miles (9 kilometers) in diameter, which covers nearly 41% of the diameter of Phobos.
The two images show Stickney to be bluer in color than its surrounding surface. Scientists think that the blue color indicates that the material inside the crater is younger than the surrounding material; thus, something impacted Phobos to make the crater.
Nathan Bridges, a member of the HiRISE team, stated, "Based on analogy with material on our own Moon, the bluer colour could mean that the material is fresher, or hasn't been exposed to space as long as the rest of Phobos's surface has.” [New Scientist (subscription required): “'Doomed' Mars moon imaged in stunning detail”]
In addition, streaks of color are seen along the sides of Stickney (along with other craters), which indicates to scientists that material has slid down sometime in its past.
Scientists think that many of the pockmarks on the surface of Phobos came when meteorites hit Mars and were flung out and hit the moon.
The two Mars Phobos images appear on the April 8, 2008 press release of NASA.
What about future missions to Phobos? Please read on.
The Russian Federation Space Agency (RSA), the China National Space Agency (CNSA), and the Finnish Meteorological Institute (Finland) are planning a joint robotic orbiter-lander sample return mission to Mars and Phobos.
The mission is now scheduled to be launched in October 2009, enter Martian orbit in September 2010, and be returned to Earth in 2012. The mission is called Phobos-Grunt.
The Chinese Yinghuo-1 would separate from Phobos-Grunt and both probes would go into orbit about Mars. Two Finnish MetNet landers would be sent off to survey the surface of Phobos and, later, returned to Earth with collected sample materials from Phobos.
The United Kingdom is also planning a sample return mission to Phobos, which is in the early planning stage.
The United States may be considering a landing on Phobos at some indeterminate time in the future. Being a much smaller body than Mars, Phobos contains less gravity than Mars and, thus, would be easier to land a spacecraft on its surface. In addition, scientists believe that material from Mars probably exists on the surface of Phobos as the result of meteorite impacts on the Martian surface that ended up on the moon.
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William Atkins completed educational degrees in science (bachelor’s in physics and mathematics) from Illinois State University (Normal, United States) and business (master’s in entrepreneurship and bachelor’s in industrial relations) from Western Illinois University