今日のテキスト NASA: FLOWING WATER ON MARS

Scientists have one more reason to believe the basic conditions to sustain life may exist on Mars. Researchers at the U.S. space agency say they've observed signs of water flowing on the planet's surface.
NASA scientists analyzed data gathered by the Mars Reconnaissance Orbiter. They focused on dark streaks that appear on some parts of the red planet when temperatures are warmer. The streaks disappear when it's cooler. The orbiter used infrared rays to analyze the chemical composition of lines that appear to flow downhill. The scientists believe the dark streaks were made by liquid water containing salt compounds.

(Jim Green / NASA Director of Planetary Science)
"Today, we are revolutionizing our understanding of this planet. Mars is not the dry, arid planet that we thought of in the past."

U.S. researchers have determined that the planet once had a large volume of water, enough for lakes and rivers. Green says further study could help scientists determine whether there is life on Mars now.