Are we humans alone in space? Scientists have been working on this question for a long time. And recently, new discoveries offer more hope that some form of life existed on Mars in the past, and perhaps is still there at present.
According to a new report in the book Science, the Mars Explorer Curiosity has found more methane (甲烷) in the Martian air. It might suggest the possibility of life.
During the last 20 months, Curiosity has found methane many times, and four of them, it tested at a level 10 times higher than usual. “It’s a great increase,” said Christopher Webster, the lead scientist.
This new finding has made a big change. In September 2013, Curiosity found almost no sign of methane on Mars. Just weeks later, however, the explorer picked up the gas.
Methane is also found in Earth’s air, and comes from animal and plant life, as well as from the environment itself. If there’s methane in Mars’ air, where is it coming from? Scientists aren’t sure.
“There are many possible sources, such as actions between water and rock,” guessed Sushil, a scientist of the Curiosity team.
But the scientists have left the possibility open that microbes (微生物) could be the methane’s source. Also, for the first time, Curiosity found other organisms (有机物) in the rocks of Mars. Organisms are thought to be the basis to form life. Scientists aren’t sure where these organisms come from. They could either have formed on Mars or landed on Mars by meteorites (陨石).
For the next three years, Curiosity will keep looking for more organisms in rocks and exploring Mars.
【小题1】Where did Curiosity recently find methane?| A．In the Martian air. | B．In the air on Earth. | C．In rocks on Mars. | D．In the water on Mars. |
| A．methane is a sign of life | B．astronauts sent to Mars have seen signs of life |
| C．the Mars Explorer has taken some photos of animals | D．the environment on Mars is similar to that on Earth |
| A．rocks | B．meteorites | C．methane | D．organisms |
| A．scientists are sure to have found life on Mars | B．methane is the basis to form life |
| C．there is more to learn about Mars | D．there are no rocks and water on Mars |
