[ti:N星和彩票A's Mars 2020 to Prepare for Humans into Deep Space] [by:www.51星和彩票.com] [00:00.00]更多听力请访问51VOA.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 N星和彩票A's mission to send humans into deep space. [00:43.16]N星和彩票A 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]N星和彩票A 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 N星和彩票A'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51VOA.COM