理工类相同项单选集试卷（八）.doc

试卷第 PAGE 1 页共 NUMPAGES 3 页 理工类相同项单选集试卷 姓名:_____________ 年级:____________ 学号:______________ 题型 选择题 填空题 解答题 判断题 计算题 附加题 总分 得分 评卷人 得分 1、Image Martian Dust Particles NASA’s Phoenix Mars Lander has taken its first ever picture of a single particle of rusty Martian dust with one of its microscopes. The dust particles of dust were shown at a higher magnification than anything outside of Earth that has been imaged before. The rounded particle measured only about one micrometer, or one millionth of a meter, across. “Taking this image required the highest resolution microscope operated off Earth and a specially designed device to hold the Martian dust,” said Tom Pike, a Phoenix science team member from Imperial College London. “We always knew it was going to be technically very challenging to image particles this small.” The device that imaged the dust speck is called an atomic force microscope, which maps the shape of particles in three dimensions by scanning them with a sharp tip at the end of a spring. The atomic force microscope can detail the shapes of particles as small as about 100 nanometers. And this won’t be the last dust particle that Phoenix will image. “After this first success, we’re now working on building up a portrait gallery of the dust on Mars,” Pike said. Dust exists everywhere on Mars, coating the surface and giving it its rusty red color. Dust particles also color the Martian sky pink and feed storms that regularly envelope the planet. The ultrafine dust is the medium that actively links gases in the Martian atmosphere to processes in Martian soil, so it is critically important to understanding Mars’ environment, the researchers said. The $ 420-million Phoenix mission is analyzing the dust and subsurface ice layers of Mars’ arctic regions to look for signs of potential past habitability. The particle seen in the atomic force microscope image was part of a sample scooped by the robotic arm from the “Snow White” trench and de