[ti:NASA's Mars 2020 to Prepare for Humans into Deep Space][by:shang05.com][00:00.00]更多听力请访问shang05.com[00:00.04]America's space agency is nearing completion of a vehicle[00:05.96]that will search for evidence of past life on Mars.[00:11.92]It is too cold and dry for life to exist on the surface of Mars today.[00:20.00]But scientists hope the rover will find evidence of life that once lived on the planet.[00:29.00]The rover will make the trip to the red planet later this year,[00:34.16]and start preparing for NASA's mission to send humans into deep space.[00:43.16]NASA recently showed off its Mars 2020 rover.[00:49.56]It has four wheels and is about the size of a car.[00:55.92]The rover will be sent to Florida's Kennedy Space Center in three parts.[01:03.44]It will be put together there.[01:05.84]The vehicle's official name will be chosen soon.[01:11.08]Launch is set for July.[01:13.92]The following February, the rover will land in the 250-meter-deep Jezero Crater[01:24.76]– a dry lake bed that is bigger than New York's Manhattan.[01:30.84]Billions of years ago, it was a deep lake, but as the climate changed there, it dried up.[01:41.36]Scientists believe that the crater holds many sediments in great condition[01:49.36]—some may be 3.5 billion years old.[01:55.16]They hope the rover will find fossils—remains of plants or animals that once lived on Mars.[02:06.36]"The trick, though, is that we're looking for trace levels of chemicals from[02:14.44]billions of years ago on Mars," Mars 2020 deputy project manager Matt Wallace told Reuters.[02:26.04]The rover will collect up to 30 samples, or small amounts, of soil.[02:35.16]NASA plans to have them picked up and returned to Earth by a future spacecraft.[02:45.08]Mars 2020 research will also be very important for future human missions to the red planet.[02:54.08]It is carrying equipment that can turn carbon dioxide,[03:00.32]which is everywhere on Mars, into oxygen for breathing.[03:08.08]If successful, Mars 2020 will mark NASA's fifth Martian rover to carry out a soft landing.[03:19.60]Important lessons were learned from the most recent Curiosity rover,[03:26.28]which landed on the planet's surface in 2012.[03:31.32]It continues to move and work on the Martian surface southeast of the Jezero Crater.[03:42.52]The former Soviet Union is the only other country to land a rover on Mars.[03:50.92]But it did not deploy.[03:53.80]China and Japan have attempted to send orbiters around Mars.[04:00.48]India and Europe's space agency have successfully sent an orbiter to the planet.[04:09.80]I'm Anne Ball. 更多听力请访问shang05.com