America's space agency is nearing completion of a vehicle that will search for evidence of past life on Mars. It is too cold and dry for life to exist on the surface of Mars today. But scientists hope the rover will find evidence of life that once lived on the planet.
The rover will make the trip to the red planet later this year, and start preparing for NASA's mission to send humans into deep space.
NASA recently showed off its Mars 2020 rover. It has four wheels and is about the size of a car. The rover will be sent to Florida's Kennedy Space Center in three parts. It will be put together there. The vehicle's official name will be chosen soon.
Launch is set for July. The following February, the rover will land in the 250-meter-deep Jezero Crater – a dry lake bed that is bigger than New York's Manhattan. Billions of years ago, it was a deep lake, but as the climate changed there, it dried up. Scientists believe that the crater holds many sediments in great condition—some may be 3.5 billion years old. They hope the rover will find fossils—remains of plants or animals that once lived on Mars.
"The trick, though, is that we're looking for trace levels of chemicals from billions of years ago on Mars," Mars 2020 deputy project manager Matt Wallace told Reuters. The rover will collect up to 30 samples, or small amounts, of soil. NASA plans to have them picked up and returned to Earth by a future spacecraft.
Mars 2020 research will also be very important for future human missions to the red planet. It is carrying equipment that can turn carbon dioxide, which is everywhere on Mars, into oxygen for breathing.
If successful, Mars 2020 will mark NASA's fifth Martian rover to carry out a soft landing. Important lessons were learned from the most recent Curiosity rover, which landed on the planet's surface in 2012. It continues to move and work on the Martian surface southeast of the Jezero Crater.
The former Soviet Union is the only other country to land a rover on Mars. But it did not deploy. China and Japan have attempted to send orbiters around Mars. India and Europe's space agency have successfully sent an orbiter to the planet.
I'm Anne Ball.
1.the red planet 火星
Scientists already suspect the red planet has water.
2.carry out 实施
I myself will firmly carry out this plan.
3.search for 搜寻
His confronting me forced me to search for the answers.
4.looking for 寻找
We've been looking for you.
5.It will be put together there.
put together 放在一起；组装
He is trying to put a team together for next season.
We got to work on putting the book together.
6."The trick, though, is that we're looking for trace levels of chemicals from billions of years ago on Mars.
billions of years ago 数十亿年前
Billions of years ago the universe was too hot for life to exist.
Billions of years ago, they say, something very large hit the earth.
美国航空航天局即将完成搜寻火星过去生命迹象的航天器的准备工作 。如今火星表面太冷、太干燥，不适合生命存活 。但是科学家们希望探测器能够发现曾经火星上生命存活的证据 。
美国航空航天局最近展示了“火星2020任务”的探测器 。该探测器有四个轮子，大小与一辆汽车差不多 。探测器将分三部分被送往佛罗里达州的肯尼迪航天中心 。它将在那里进行组装 。探测器的正式名称将很快选定 。
发射时间定于7月 。今年2月，探测器将在250米深的Jezero陨石坑着陆，这是一个干涸的湖床，比纽约的曼哈顿还大 。数十亿年前，这是一个很深的湖泊，但随着气候变化，湖泊干涸了 。科学家们认为，这个陨石坑里有许多保存完好的沉积物，其中一些可能长达35亿年 。他们希望探测器能发现火星上曾经生活过的动植物的化石 。
“关键在于，我们正在寻找数十亿年前火星上的微量化学物质，”火星2020项目副经理马特·华莱士告诉路透社 。探测器将收集30个样本，或少量土壤 。美国航空航天局计划用未来的宇宙飞船将它们接回地球 。
“火星2020年”项目的研究对未来人类前往火星的任务也至关重要 。其携带的设备能将火星上弥漫的二氧化碳转化为可供呼吸的氧气 。
如果成功，“火星2020”将标志着美国宇航局的第五个火星探测器实现软着陆 。2012年，最新的“好奇号”探测器在火星表面着陆为此提供了宝贵的经验 。它会继续在Jezero陨石坑东南的火星表面移动和工作 。
前苏联是唯一一个将探测器送上火星的国家 。但它没有得到有效利用 。中国和日本已经尝试发射绕火星轨道飞行器 。印度和欧洲航天局已经成功地向火星发射了一颗人造卫星 。