题型:阅读理解 题类: 难易度:困难
辽宁省重点高中协作校联考2024届高三下学期4月高考模拟考试英语试题
Deep below the ground, radioactive elements break up water molecules(分子), producing substances that can fuel subsurface life. This process, known as radiolysis(辐射分解),has supported bacteria in tiny cracks filled with water on Earth for millions to billions of years. Now a study published in Astrobiology shows that radiolysis may have supported life in the Martian subsurface.
Dust storms, rays in the universe and solar winds ruin the Red Planet's surface. But below, some life might find shelter. "The best survival habitat on Mars is the subsurface," said Jesse Tarnas, a planetary scientist at NASA, Examining the Martian underground could help scientists learn whether life existed there. And the best subsurface samples available today are Martian meteorites(陨石) that have crash-landed on Earth.
Tarnas and his colleague looked at the minerals on the Martian surface and how many radioactive elements there were, using satellite and rover data, They used computers to simulate(模拟) radiolysis to see how efficiently the process would have generated life-supporting hydrogen gas and other chemical substances. They reported that if water was present, radiolysis could have supported life for billions of years and perhaps still could today.
Scientists had previously studied Mars radiolysis, but this marked the first estimate using Martian rocks to see how habitable Mars underground might be. Tarnas and his colleagues also evaluated the potential richness of life in Martian underground.They found that up to a million bacteria could exist.in just one kilogram of rock, The most habitable seemed to be the southern highlands of Mars, which is the most ancient area on Mars, according to Tarnas.
"Underground life would require water and it remains unknown if groundwater exists on the planet," says Lujendra Ojha, a planetary scientist at Rutgers University. Determining whether the Martian, subsurface contains water. will be an important next step, but this investigation helps to motivate that search, Ojha says, "Where there is groundwater, there could be life."
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