鏈接：https://www.bilibili.com/video/BV1Kh411q7KW

Martian（火星的，火星人） Crust（地殼） Could Sustain（維持） Life through Radiation（輻射）

Meteorites（隕石）?reveal that so?long as groundwater is present, the Martian subsurface（地表下層） is habitable

Meteor 流星?? Meteoroid 流星體

habitable ：可居住的? inhabitable 可居住的 uninhabitable 不可居住的

Deep below the ground, radioactive elements disintegrate（分解v.） water molecules（分子）, producing ingredients that can fuel subterranean（地下的） life. This process, known as radiolysis（輻射分解）, has sustained bacteria in isolated,water-filled cracks（裂縫） and rock pores（氣孔） on Earth for millions to billions of years.Now a study published in?Astrobiology（天體生物學(xué)）?contends（提出涨醋，主張） that radiolysis could have powered microbial（微生物的） life in the Martian subsurface.

integrate ：整合? mediintegrate 地中海的

pore溯警、porous多孔的喳挑、porosity滲透性

microbe微生物

Dust storms（沙塵暴）, cosmic?rays（宇宙射線） and solar winds ravage（摧毀） the Red Planet’s surface. But belowground（地下的）, some life might find refuge（避難處）. “The environment with the best chance of（...機(jī)會） habitability on Mars is the subsurface,”says Jesse Tarnas, a planetary scientist at NASA’s Jet Propulsion Laboratory（噴氣式推進(jìn)實(shí)驗(yàn)室） and the new study’s lead author（第一作者）. Examining the Martian underground could help scientists learn whether life could have survived there—and the best subsurface samples available today are Martian meteorites（隕石） that have crash-landed（緊急降落） on Earth.

cosmonaut 蘇聯(lián)宇航員

take refuge 找避難處

co-author 聯(lián)合作者

Tarnas and his colleagues evaluated the grain sizes（粒徑）,mineral make up and radioactive element abundance（含量） in Martian meteorites and estimated the Martian crust’s porosity（滲透性） using satellite and rover（火星車）?data. They plugged these attributes（特性） into a computer model that simulated（模擬） radiolysis to see how efficiently the process would have generated hydrogen gas and sulfates（硫酸鹽）:chemical ingredients that can power the metabolism（新陳代謝） of underground bacteria. The researchers report that if water was present, radiolysis in the Martian subsurface could have sustained microbial communities（群落） for billions of years—andperhaps still could today.

plug into ...把...接入...

Scientists have previously studied Mars radiolysis,but this marks the first estimate using Martian rocks to quantify（量化） the planet’s subsurface habitability. Tarnas and his colleagues also evaluated the potential richness of life in the Martian underground and found that as many as a millionmicrobes could exist in a kilogram of rock. (Geobiologists（地球生物學(xué)家） have found comparable（相當(dāng)?shù)模?/b> densities in Earth’s subsurface.)

The most habitable meteorite samples analyzed appearedto be made of a rock type called regolith（風(fēng)化層） breccia（角礫巖）. “These are thought to come from the southern highlands of Mars, which is the most ancient terrain（地勢） on Mars,” Tarnas says.

Underground life, as described by this research, would require water—and it remains unknown if groundwater exists on the planet, says Lujendra Ojha, a planetary scientist at Rutgers University, who was not involved in the study. Determining（查明） whether the Martian crust contains waterwill be an important next step, but this investigation helps to motivate that search, Ojha says: “Where there is groundwater, there could be life.”