火星上的傍晚時分

NASA發射的火星探測器Opportunity最近拍攝了一幅火星一個隕石坑邊緣的照片。

該探測器是由2003年7月7日發射。於2004年1月25日着陸於火星表面。

該探測器設計壽命是三個月。但由於火星上的風可以給它的太陽能板清理積塵，從而使得它的壽命大幅度延長。至今，這個探測器工作良好。它已在火星上工作了8年整。

這個探測器是今年三月9日火星上的下午4點半到5點之間，用不同的濾色片拍攝，最後合成在一起的一幅照片。

照片前方的陡峭部分是Endeavour Crater的邊緣。上半部是該隕石坑內的地形。

在照片上可見，火星上的天空是淡紅色的。該探測器的太陽能板在照片上清晰可見。其中的縫隙積滿了火星上紅色的塵土。太陽能板被火星上的風吹得很乾淨，這是它能超常服役的根本原因。

這是Opportunity探測器在前幾年拍攝的Victoria Crater 邊緣照片。照片上的岩石清晰的分層結構，這是火星在地質歷史上曾存在液態水的有力證據。

下面是NASA網站上介紹該照片的文字。最後是該照片的外鏈地址。

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