题型：阅读理解 题类：常考题 难易度：普通
2016届江西省新余市第一中学高三下学期高三模拟考试英语试卷
The streams are about 12 to 15 feet wide and 300 feet or more long, scientists said. "What we're dealing with is wet soil, thin layers of wet soil, not standing water," said Aifred McEwen of the University of Arizona at Tueson! the principal scientist for the Mars Reconnaissance Orbiter's high-resolution imaging experiment,
Because liquid water is essential to life, the findings could have major implications for the possibility of Martianlife, There searchers said further exploration is needed to determine whether microscopic life exists on the planet.
The presence of liquid water could also make life easier for astronauts visiting or living on Mars. Watercould be used for drinking and for creating oxygen and rocket fuel. NASA's goal is to send humans there inthe 2030s.
The evidence of flowing water consistslargely of dark, narrow streaks(条痕) on the surface that tend to appear and growd uring the warmest Martian months and fade the rest of the year.
Mars is extremely cold even in summer,and the streaks are in places where the temperature is as low as minus 10 degrees Fahrenheit. But salt can lower the freezing point of water and melt ice.
The source of the water is a mystery. Scientists noted it could be melting ice. It could be an underground a quifer, which is rock or sand that can hold water. It is possibly water vapor from the thin Martian atmosphere, Or it may be a combination Michael Meyer, lead scientistfor NASA's Mars exploration program, said the only definitive way for now to determine whether there's life on Mars is to collect rocks and soil foranalysis on Earth - something a U.S. lander set for lift-off in 2020 will do.
To the Editors: I am surprised to read that Dr. Strojnik ("Direct Detection of Exoplanets," September-October2023) states that we have not yet and cannot directly image exoplanets (外部行星). This is incorrect. NASA/IPAC has a list at exoplanetarchive.ipac.caltech.edu/does/imaging.html. One example is an image of 51 Eridani b. The planet is 2.6 times as massive as Jupiter and has the same radius (半径). Gerard Kriss Space Telescope Science Institute |
Dr. Gerard: I am pleased that my article brought a response. The phrase "planet detection" arouses in people's imaginations beautiful images of planets that are creative artistic representations of novel worlds. But a blur of brightness is not an image. Exoplanet researchers routinely call videos such as the one below of 51 Eridani b "direct images" because the planet's light has been separated from that of its star. "Directly imaged" is the standard language of exoplanet astronomy. But to an optical (光学的) scientist such as myself, there is a strong distinction between direct detection (the planet's light separated from the light of its star) and direct imaging (a proven picture of the exoplanet). From an optical researcher's perspective, a single bright spot simply is not an image. Indeed, even the word "direct" in direct detection is debatable from an optical researcher's point of view. The detection of the light of the exoplanet requires significant processing, adding multiple images and removing starlight based on theoretical models of the source signal. But the interpretation of a bright spot as a planet is only possible upon visual inspection and optimistic thinking. As an optical scientist, I cannot look at a single spot and call it an image of exoplanets. A trajectory (轨迹), or a series of bright points, is not an image of a planet, although it very likely represents something that nowadays is described as an exoplanet. Marija Strojnik |
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