Scientists are seeking to find out what is producing the slow release of methane gas on Mars.
科学家们正在寻找火星上缓慢释放甲烷气体的原因。
Methane often results from biological processes. On Earth, most of the gas comes from living creatures. For this reason, the American space agency NASA has been investigating methane levels on Mars in a search for signs of current or past life. So far, no evidence has been found.
甲烷通常来自生物过程。在地球上，大部分气体来自生物。出于这个原因，美国宇航局NASA一直在调查火星上的甲烷水平，以寻找当前或过去生命的迹象。到目前为止，还没有找到任何证据。
But a new study is providing fresh details about methane on Mars. NASA’s Curiosity explorer, or rover, has repeatedly measured methane levels on the Martian surface. The rover arrived on Mars in 2012 and has been exploring areas around Gale Crater. This area is believed to have contained a lake at one time and has also shown other evidence of flowing water in the past.
但一项新研究提供了有关火星甲烷的新细节。美国宇航局的好奇号探测器或漫游者多次测量了火星表面的甲烷水平。该火星车于 2012 年抵达火星，一直在探索盖尔陨石坑周围的区域。据信该地区曾经有一个湖泊，并且过去还显示出其他流水的证据。
NASA says Gale Crater is the only place where methane has been discovered. Even a spacecraft sent to collect data on the Martian atmosphere has not identified the presence of methane. That spacecraft, the ExoMars Trace Gas Orbiter, is operated by the European Space Agency.
美国宇航局表示，盖尔陨石坑是唯一发现甲烷的地方。即使是派去收集火星大气数据的航天器也没有发现甲烷的存在。该航天器名为 ExoMars 痕量气体轨道飞行器，由欧洲航天局运营。
In addition to only being discovered, or detected, around Gale Crater, the observations of methane happen only at night, NASA researchers recently reported . Levels also go up and down during different seasons and at times, rise sharply for short periods.
美国宇航局研究人员最近报告说，除了仅在盖尔陨石坑周围发现或探测到甲烷之外，甲烷的观测也只发生在夜间。水平也会在不同季节上下波动，有时会在短时间内急剧上升。
The mysterious methane releases leave scientists considering “a lot of plot twists ,” said Curiosity project leader Ashwin Vasavada. But a NASA research group recently proposed a possible explanation for how the gas behaves on Mars.
好奇号项目负责人阿什温·瓦萨瓦达 (Ashwin Vasavada) 表示，神秘的甲烷释放让科学家们思考“许多情节曲折”。但美国宇航局的一个研究小组最近对火星上的气体行为提出了一个可能的解释。
The researchers theorize that all detected methane could be trapped, or sealed, underneath hardened pieces of salt in Martian regolith. Regolith describes soil that contains rock and dust that sits on or below the surface.
研究人员推测，所有检测到的甲烷都可能被捕获或密封在火星风化层的硬化盐块下面。风化层描述的是含有岩石和灰尘的土壤，位于地表之上或之下。
The scientists say increases in temperature might explain the differences in gas release. During certain seasons or times of day warmer temperatures could weaken the seal on the methane, causing gas to be released.
科学家们表示，温度升高可能可以解释气体释放的差异。在某些季节或一天中的某些时间，气温升高可能会削弱甲烷的密封性，导致气体释放。
NASA said the research was led by Alexander Pavlov, a planetary scientist at the agency’s Goddard Space Flight Center in Maryland. He said small amounts of methane could also be released when the regolith seal is broken by weight from above, for example, when the Curiosity rover drives over the area.
美国宇航局表示，这项研究是由该机构马里兰州戈达德太空飞行中心的行星科学家亚历山大·巴甫洛夫领导的。他说，当风化层密封被上方的重量破坏时，例如当好奇号火星车驶过该地区时，也可能释放少量甲烷。
Pavlov said this theory could help explain why methane levels have only been discovered in the Gale Crater area. It is the only place on Mars where NASA’s Curiosity rover is currently active.
巴甫洛夫说，这一理论可以帮助解释为什么只在盖尔陨石坑地区发现了甲烷水平。这是美国宇航局好奇号火星车目前在火星上唯一活跃的地方。
NASA has another rover working on Mars, Perseverance. But it has been exploring the Jezero Crater area on another part of the planet. Jezero Crater is also believed to have contained large water bodies in the distant past. But Perseverance is not equipped with a methane-detecting instrument.
美国宇航局还有另一辆火星车“毅力号”正在火星上工作。但它一直在探索地球另一部分的杰泽罗陨石坑地区。据信，杰泽罗陨石坑在遥远的过去也曾存在过大型水体。但毅力号并未配备甲烷检测仪器。
Pavlov noted that the latest theory came from his memories of an unrelated experiment carried out in 2017. The experiment involved growing microorganisms in a simulated Martian environment that included frozen soil that contained salt.
巴甫洛夫指出，最新的理论来自他对 2017 年进行的一项无关实验的记忆。该实验涉及在模拟火星环境中培养微生物，其中包括含盐的冻土。
During that experiment, researchers observed that the collection of soil on top formed an icy, salty crust . Changes in conditions caused the ice to melt, turning the solid material into a gas and leaving the salt behind.
在那次实验中，研究人员观察到，顶部的土壤聚集形成了冰冷、含盐的外壳。条件的变化导致冰融化，将固体物质变成气体并留下盐。
Pavlov’s team tested five samples of frozen soil containing different kinds of salt material commonly found on Mars. A new set of Earth-based experiments was carried out in which the frozen material was exposed to different temperatures and air pressures inside an environment at Goddard that was designed to be like Mars.
巴甫洛夫的团队测试了五个冻土样本，其中含有火星上常见的不同种类的盐物质。进行了一系列新的地球实验，将冷冻材料暴露在戈达德的一个类似火星环境的不同温度和气压下。
The team was able to repeatedly copy the salt sealing process in Mars-like conditions during laboratory testing. The researchers said they plan to keep carrying out experiments under different conditions and using salt minerals to confirm their theory.
在实验室测试期间，该团队能够在类似火星的条件下重复复制盐密封过程。研究人员表示，他们计划继续在不同条件下进行实验，并利用盐矿物质来证实他们的理论。
But the researchers noted that to carry out more detailed methane investigations, they will likely need a whole new generation of sensitive instruments. These would be designed to measure methane continuously from many places on Mars.
但研究人员指出，为了进行更详细的甲烷研究，他们可能需要全新一代的敏感仪器。这些将被设计用于从火星上的许多地方连续测量甲烷。