中文导读：美国国家航天航空局在地球以外发现生命，航天局会继续在太阳系搜寻生命迹象。科学家称搜寻设备越来越先进，他们强调了开普勒望远镜的作用，称该工具对外星球的知识扩展起关键性作用。该望远镜还会帮助科学家了解外星球是否含有水蒸汽和二氧化碳。外星球位于太阳系外。一个地球大小的外星球运行轨道被叫做“适居区”，该区域可以为外星球提供液态水，液态水对生命至关重要。在航天局开会讨论期间回答了公众的问题，有人问是否会对公众公开在地球外发现生命，航天局回答会公开。
NASA scientists say they are closer than ever to finding life beyond Earth.
Several leading NASA scientists spoke to a gathering July 14th at NASA headquarters in Washington, D.C. The scientists discussed the space agency’s plan to find life in outer space.
NASA continues to look for life in the solar system. That search is centered mostly on Mars and the icy moons of Jupiter and Saturn. But the scientists mainly discussed the search for life outside the solar system.
NASA Administrator Charles Bolden opened the talk. He said it is not probable that humans are alone in what he calls “the limitless vastness of the universe."
The scientists spoke about improvements in search equipment. They noted the Kepler Space Telescope. They said the tool had been critical in expanding knowledge about exoplanets.
An exoplanet is a planet that orbits a star outside the solar system. Keplerhas discovered most of the 5,000 possible exoplanets, of which almost two thousand have been confirmed.
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An Earth-size exoplanet orbits what is called, the “habitable zone” of a star. The habitable zone is an area which could support liquid water on theexoplanet. Liquid water is considered essential for life as we know it.
Kepler research has led scientists to believe that there may be billions of planets in the galaxy.
Sara Seager is a professor of planetary science and physics at the Massachusetts Institute of Technology in Cambridge, Massachusetts. She says space scientists think it is “very likely that every single star in the MilkyWay galaxy has at least one planet.”
Another major step toward discovery is the planned launch of three new telescopes. Officials expect to deploy the equipment starting in 2017.
These telescopes will help scientists to learn if an exoplanet has atmospheric water vapor or carbon dioxide.
Ms. Seager says these three telescopes will give scientists the ability to find life on other planets. But she adds they will also need luck. It is a very big universe.
During the discussion, the group of scientists took questions from the public. One person asked if the United States government would tell the public of a discovery of life outside of Earth.
NASA's chief scientist Ellen Stofan answered, “Of course we would.”
I’m Anna Matteo.
