said at a news conference on September 28, 2015.
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 Alfred McEwen of the University of Arizona at Tucson, 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 Martian life. The researchers 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. Water could be used for drinking and for creating oxygen and rocket fuel. NASA's goal is to send humans there in the 2030s.
The evidence of flowing water consists largely of dark, narrow streaks (条痕) on the surface that tend to appear and grow during 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 (源头) of the water is a mystery. Scientists noted it could be melting ice. It could be an underground aquifer, 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.
【2017届高考北师大版英语二轮复习单元限时规范练:必修4 Unit 10《money》(含解析)】相关文章:
★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (40)
★ (安徽专用)2014届高考英语一轮复习方案 作业手册(10)模块4 《Unit 10 Money》(含解析) 北师大版必修1
★ 北京市2014高考英语一轮复习 练习手册(19)必修4 Unit 4 Body language(含解析)新人教版
★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (51)
★ 北京市2014高考英语一轮复习 练习手册(40)选修8 Unit 5 Meeting your ancestors(含解析)新人教版
★ 2017高考四川省广安市英语阅读理解一轮系列训练:8(含解析)
★ 【课堂新坐标】2017届高考英语(通用版)二轮复习短文改错专题训练:考法3 行文逻辑错误(含解析)
★ 2014年牛津译林版高中英语总复习(第1轮)同步练习 M11《Unit 4 The next step》Word版含解析
★ 【三维设计】2017届高考英语(江苏专用)二轮复习课件:必修4 Unit 3《Tomorrow’s world》
★ (全国通用)2014届高考英语一轮单元复习 限时强化训练十二
最新
2017-04-24
2017-04-24
2017-04-24
2017-04-24
2017-04-21
2017-04-21