火星岩石中發現氮元素

U.S. space researchers say they have found more evidence that the planet Mars could have once been able to support life.

美國太空研究人員說，他們發現更多證據顯示火星可能曾經存在能夠維持生命的環境。

NASA scientists said Tuesday the Curiosity Mars rover found nitrates in Martian rocks. Nitrates are compounds that contain nitrogen, an element essential for life.

美國航空航天局的科學家們星期二說，火星探測器“好奇號”在火星岩石中發現了硝酸鹽。硝酸鹽中含有氮，而氮是維持生命的必要元素。

But the scientists say there is no evidence the nitrogen came from living things and stress that the Martian surface cannot support any forms of life.

但科學家們說，沒有證據顯示火星上的氮來自生物，並強調火星表面不能維持任何形式的生命。

They believe the nitrates are ancient and probably came from meteorites or lightning strikes.

科學家們相信，火星上的硝酸鹽存在已久，很可能來自流星或閃電。

This is not the first sign that the planet may have at one time been habitable. Past discoveries show signs that fresh water once covered the Martian surface.

目前還沒有跡象顯示火星可能曾經適於居住。過去發現，火星表面曾被淡水覆蓋。