[新闻] “卡西尼”传回土卫八照片 将揭开两面之谜 [酷图]

美国喷气推进实验室的科学家15日报告说，绕土星运行的“卡西尼”号飞船传回了土卫八的新照片，他们期待这些照片能为解开土卫八的“两面”之谜提供线索。

　　土卫八直径为1436公里，大约是月球的三分之一。它一个半球黑暗无光，另一个半球非常明亮。科学家还不能确定覆盖土卫八黑暗半球的物质的来源，一种理论是，这些物质是土星的小卫星土卫九喷射过来的；还有一种说法是，这些物质来自于土卫八内部。

　　土卫八的这些照片是“卡西尼”号于3日在距土卫八约300万公里处拍摄的。“卡西尼”号飞船发射升空近7年、在太空遨游35亿公里后于6月30日进入绕土星轨道，成为绕土星运行的第一个人造飞行物。从7月5日到12日，太阳处于“卡西尼”号和地球之间，“卡西尼”号只做了非常有限的科学研究工作。

　　“卡西尼”号探测计划耗资33亿美元，由美国、欧洲和意大利宇航局联合实施。(记者 曲俊雅)

Saturn's Two-Face Moon
07.15.04  


The moon with the split personality, Iapetus, presents a puzzling appearance. One hemisphere of the moon is very dark, while the other is very bright. Whether the moon is being coated by foreign material or being resurfaced by material from within is not yet known.

Iapetus' diameter is about one third that of our own moon at 1,436 kilometers (892 miles). The latest image was taken in visible light with the Cassini spacecraft narrow angle camera on July 3, 2004, from a distance of 3 million kilometers (1.8 million miles) from Iapetus (pronounced eye-APP-eh-tuss).

The brightness variations in this image are not due to shadowing, they are real. The face of Iapetus visible was observed at a Sun-Iapetus-spacecraft, or phase, angle of about 10 degrees. The image scale is 18 kilometers (11 miles) per pixel. The image was magnified by a factor of two to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Credit: NASA/JPL/Space Science Institute


 
　　来源： 新华网  2004-07-16 16:32

奇怪的家伙

The icy, cratered surface of Saturn's moon Dione shows more than just its sunlit side in these two processed versions of the same image.

The view at left, with only mild enhancement, shows a romantic crescent with large craters visible. The contrast in the version at the right has been greatly enhanced to show the side of Dione lit faintly by reflected light from Saturn. A similar phenomenon can be seen from Earth, when the Moon?s dark side is visible due to "earthshine." The crater at the top of the image appears to have a sunlit central peak in the enhanced view -- a common characteristic of craters on Dione as seen in Voyager images. Slight variations in brightness on the moon?s dark side hint at the bright curved linear streaks, seen by Voyager. These streaks are thought to be deposits of water ice.

The image was taken with the Cassini spacecraft narrow angle camera on July 2, 2004, from a distance of about 1.4 million kilometers (860,000 thousand miles) from Dione, at a Sun-Dione-spacecraft, or phase angle of about 119 degrees. The image scale is 8 kilometers (5 miles) per pixel. Dione's diameter is 1,118 kilometers (695 miles) across. The images have been magnified by a factor of two to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Crescent Rhea
07.20.04

The first artificial satellite in the Saturn system, the Cassini spacecraft, returned images of the natural moons following a successful insertion into orbit. This is an unmagnified view of the moon Rhea.

With a diameter of 1,528 kilometers (950 miles) across, Rhea is Saturn's second largest moon. The Voyager spacecraft found that like Dione, Rhea has one of its hemispheres covered with bright, wispy streaks which may be water frost.

This view shows a heavily cratered surface, and thus it is most likely ancient. Many of the craters visible here have central peaks. Cassini soon will look for clues to help unlock the moon's geologic history. The spacecraft is slated to fly by Rhea at a distance of only 500 kilometers (311 miles) on Nov. 26, 2005.

The image was taken in visible light with the Cassini spacecraft narrow angle camera on July 2, 2004, from a distance of about 990,000 kilometers (615,000 miles) from Rhea and at a Sun-Rhea-spacecraft, or phase angle of about 109 degrees. The image scale is 6 kilometers (4 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Like a half-full moon, cratered Tethys hangs before the Cassini spacecraft in this narrow angle camera view taken on July 3, 2004.

Voyager images showed a large fracture on Tethys about 750 kilometers (470 miles) long (not seen in this view). Cassini will investigate this and other features on Tethys during two planned flybys, the first occurring on September 24, 2005. Tethys is 1,060 kilometers (659 miles) across.

The image was taken in visible light from a distance of 1.7 million kilometers (1 million miles) from Tethys and at a Sun-Tethys-spacecraft, or phase angle of about 97 degrees. The image scale is 10 kilometers (6 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

Icy Enceladus
07.23.04  



Saturn's brilliant jewel, water-ice-covered Enceladus, is the most reflective body in the solar system.

Reflecting greater than 90 percent of the incidental sunlight, this moon was the source of much surprise during the Voyager era. Enceladus (pronounced "en-SELL-uh-duss"), exhibits both smooth and lightly cratered terrains that are crisscrossed here and there by linear, groove-like features. It also has characteristics similar to those of Jupiter's moons, Ganymede and Europa, making it one of Saturn's most enigmatic moons.

Cassini will investigate its rich geologic record in a series of four planned close flybys. The first flyby is scheduled for Feb. 17, 2005.

The image was taken in visible light with the Cassini spacecraft narrow angle camera on July 3, 2004, from a distance of 1.6 million kilometers (990,000 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase angle of about 103 degrees. The image scale is 10 kilometers (6 miles) per pixel. Enceladus is roughly 499 kilometers (310 miles) across. The image has not been magnified.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.