2. 职称英语
  3. NASA’s new Mars probe, a $ 2. 5 billion, nuclear-powered rover the size of a

NASA’s new Mars probe, a $ 2. 5 billion, nuclear-powered rover the size of a

游客2025-03-30  11
问题    NASA’s new Mars probe, a $ 2. 5 billion, nuclear-powered rover the size of a small car, is at the Florida launch site being prepared for its nine-month journey to the red planet, with one key issue still unresolved — where to land.
   The Mars Science Laboratory, nicknamed Curiosity, will delve deeper than any previous science mission to answer the age-old question about whether there is life beyond Earth. The goal of the project is to determine if the region where Curiosity lands has or ever had the right conditions to support microbial life.
   Scientists spent years poring over pictures and analyzing chemical data collected by a fleet of robotic spacecraft circling Mars before narrowing down the options to four finalists; Eberswalde Crater, Mawrth Vallis, Holden Crater and Gale Crater.
   " Each site has things that make it good and things that make it not quite so good," said planetary scientist Matt Golombek. " It’s kind of hard to select because it boils down to which kind of science is important to you, and that’s almost personal.
   The rover will touch down within a 12. 4-by-15. 5 mile targeted area, a relatively small patch of real estate for interplanetary travel. Being able to make a precision touchdown hasn’t made things easy for scientists tapped to choose Curiosity’s landing spot. In the past, lots of scientifically interesting sites were eliminated because of concerns the spacecraft wouldn’t be able to make a safe landing.
   Eberswalde Crater stands out among the four contenders because of a single, stunning geologic feature -— a delta, believed to be a buildup of sediment left by flowing water.
   " If you want a site that probably has the highest chance of preserving organics and biosignatures that might have existed, this is the place," Golombek said. " It’s just a spectacular example where water came and built up a sediment. "
   The attractive Eberswalde site, however, has a serious drawback as well. If its deposits turn out to be nothing more than clay-dusted rocks, the mission would be largely a bust.
   The next candidate site, Mawrth Vallis, is an open book of Martian history, with exposed valley walls that date back about 3.7 billion years, nearly as old as the planet itself. Its clays, known as phyllosilicates, form in the presence of water, believed to be a necessary ingredient for life. Mawrth’s short-coming is that scientists don’t understand how it formed. Water that once flowed in the valley could have been far too acidic for life to flourish. [br] What is true about Eberswalde Crater?
选项 A、The delta shows that life might have existed there.
B、Clay-dusted rocks characterize the deposits there.
C、The sediment must have resulted from acidic water.
D、Having water makes it the best choice for the mission.
答案 A
解析 本题是正误判断题，考查第六段至第九段中提到的一些信息，可以用“找错、排除”的方法确定最佳选项。
转载请注明原文地址:http://tihaiku.com/zcyy/4019681.html
相关试题推荐
随机试题
最新回复(0)