火星上的傍晚时分 NASA发射的火星探测器Opportunity最近拍摄了一幅火星一个陨石坑边缘的照片。 该探测器是由2003年7月7日发射。于2004年1月25日着陆于火星表面。 该探测器设计寿命是三个月。但由于火星上的风可以给它的太阳能板清理积尘，从而使得它的寿命大幅度延长。至今，这个探测器工作良好。它已在火星上工作了8年整。 这个探测器是今年三月9日火星上的下午4点半到5点之间，用不同的滤色片拍摄，最后合成在一起的一幅照片。 
照片前方的陡峭部分是Endeavour Crater的边缘。上半部是该陨石坑内的地形。 在照片上可见，火星上的天空是淡红色的。该探测器的太阳能板在照片上清晰可见。其中的缝隙积满了火星上红色的尘土。太阳能板被火星上的风吹得很干净，这是它能超常服役的根本原因。 
这是Opportunity探测器在前几年拍摄的Victoria Crater 边缘照片。照片上的岩石清晰的分层结构，这是火星在地质历史上曾存在液态水的有力证据。 下面是NASA网站上介绍该照片的文字。最后是该照片的外链地址。 Opportunity's Selfie NASA's Mars Rover Opportunity catches its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars.
The rover used the panoramic camera (Pancam) between about 4:30 and 5:00 p.m. local Mars time to record images taken through different filters and combined into this mosaic view.
Most of the component images were recorded during the 2,888th Martian day, or sol, of Opportunity's work on Mars (March 9, 2012). At that time, Opportunity was spending low-solar-energy weeks of the Martian winter at the Greeley Haven outcrop on the Cape York segment of Endeavour's western rim. In order to give the mosaic a rectangular aspect, some small parts of the edges of the mosaic and sky were filled in with parts of an image acquired earlier as part of a 360-degree panorama from the same location.
Opportunity has been studying the western rim of Endeavour Crater since arriving there in August 2011. This crater spans 14 miles (22 kilometers) in diameter, or about the same area as the city of Seattle. This is more than 20 times wider than Victoria Crater, the largest impact crater that Opportunity had previously examined. The interior basin of Endeavour is in the upper half of this view.
The mosaic combines about a dozen images taken through Pancam filters centered on wavelengths of 753 nanometers (near infrared), 535 nanometers (green) and 432 nanometers (violet). The view is presented in false color to make some differences between materials easier to see, such as the dark sandy ripples and dunes on the crater's distant floor.
Image credit: NASA/JPL-Caltech/Cornell/Arizona State Univ. http://www.nasa.gov/images/content/652371main_mars_iotd_full_full.jpg |
