Methane Mystery on Mars: Could It Mean Life?
火星甲烷之谜：它意味着有生命存在吗？
The United States space agency, NASA, says its Mars exploration vehicle recently recorded a high level of methane gas on the planet. The discovery is exciting because the presence of methane gas could support the case for life on Mars.
美国太空机构NASA（美国国家航空和宇宙航行局）表示其火星探测器近期显示在这个星球上的甲烷气体浓度很高。这个发现令人很兴奋，因为甲烷气体的存在可以为火星上有生命存在提供支持性的依据。
NASA’s Curiosity vehicle recently recorded the largest level of methane ever measured during its seven-year Mars mission.
NASA的好奇号火星车近期显示出其七年火星任务期间测得的最高甲烷浓度。
Methane has no color or smell. A special instrument on Curiosity’s Mars Science Laboratory recorded the increased gas level. The device, called a laser spectrometer, measures levels of chemical elements and gases in the Martian atmosphere. In addition to methane, the instrument can record levels of water and carbon dioxide.
甲烷是一种无色无味的气体。好奇号火星科学实验室的一个特殊的仪器显示气体浓度的增加。这个叫做激光分光计的设备用于检测火星大气中化学元素和气体的浓度。除了甲烷之外，这个仪器也记录水和二氧化碳的浓度。
Nearly all the methane gas found in Earth’s atmosphere is produced by biological activity. It usually comes from animal and plant life. But it can also be formed by geological processes, such as interactions between rocks and water.
地球大气中发现的所有甲烷气体几乎都由生物活动产生。它通常来自有生命的动物和植物。但是它也可以由岩石和水之间的相互作用等地质过程形成。
NASA said the increased methane was measured to be about 21 parts per billion by volume (ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.
NASA表示测量到甲烷增加的浓度约为按体积计算的十亿分之二十一（21ppbv）。1ppbv的意思是如果你取火星气体中一个单位体积的气体，那么这个单位体积气体中十亿分之一为甲烷。
It was not the first time Curiosity has found methane gas in the Martian atmosphere. About a year ago, NASA announced that Curiosity had discovered sharp seasonal increases in the gas.
这并不是好奇号首次在火星大气中检测到甲烷气体。大约一年前，NASA宣布好奇号气体中存在剧烈的季节性增加。
This time, NASA said the measured methane gas level was clearly larger than any others observed in the past. NASA officials even temporarily stopped Curiosity’s other activities to investigate further.
这次，NASA表示测量到的甲烷气体浓度比过去任何时候观察到的浓度明显要高很多。NASA官员表示甚至暂停了好奇号的其他活动来进行进一步调查。
“It's exciting because microbial life is an important source of methane on Earth,” NASA said in a statement announcing the discovery.
“这令人很激动因为微生物是地球上甲烷气体的重要来源，”NASA在宣布这个发现的声明中表示。
However, Curiosity’s team carried out a follow-up methane experiment that showed a sharp drop in levels of the gas. The second examination found the level was less than one part per billion by volume. That number was “close to the background levels Curiosity sees all the time,” NASA said.
然而，好奇号团队进行了后续的甲烷实验，实验显示其在气体中含量急剧下降。第二次检验显示其浓度降低了1ppbv。NASA表示那个数值跟好奇号一直以来检测到的本底水平很接近。
The rise and fall of the methane gas levels left NASA scientists with more questions than answers. The scientists are continuing to study possible causes for the sudden increase.
甲烷气体浓度时高时低让NASA产生了更多迷惑而非更多的解答。科学家正在继续研究浓度突然上升的可能起因。
"The methane mystery continues," said Ashwin Vasavada, Curiosity's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere."
“甲烷之谜继续存在，”阿什温·瓦萨瓦达称。他是位于加利福尼亚帕萨迪娜的NASA喷气推进实验室好奇号项目的科学家。“我们的积极性比以前更加高昂来保持测量并集中我们的智慧去弄清楚甲烷在火星大气中的行为。”
Curiosity does not have instruments that can exactly identify whether the source of the methane is biological or geological. One leading theory is that methane is being released from underground areas created by possible life forms that disappeared long ago.
好奇号没有仪器能确切地鉴定甲烷的来源是来自生物还是地质活动。一个重要的理论是甲烷可能是由很久以前消失的生命形式产生并从地表下释放出来的。
Even though Mars has no active volcanoes, scientists believe it is also possible that methane is being produced by reactions involving carbon materials and water.
即使火星没有活火山，科学家认为甲烷也可能由碳材料和水等物质相互作用而产生的。
A clearer understanding of methane levels over time “could help scientists determine where they're located on Mars,” NASA said. Scientists hope this understanding will come as Curiosity continues to collect methane data in its search for possible life.
慢慢地对甲烷浓度有更清楚的认识“能帮助科学家确定它们在火星上的位置，”NASA表示。科学家希望随着好奇号在寻求可能存在的生命迹象中继续搜集甲烷数据来了解这个现象。
I’m Bryan Lynn.
布赖恩·林恩为您报道。
Methane Mystery on Mars: Could It Mean Life?
The United States space agency, NASA, says its Mars exploration vehicle recently recorded a high level of methane gas on the planet. The discovery is exciting because the presence of methane gas could support the case for life on Mars.
NASA’s Curiosity vehicle recently recorded the largest level of methane ever measured during its seven-year Mars mission.
Methane has no color or smell. A special instrument on Curiosity’s Mars Science Laboratory recorded the increased gas level. The device, called a laser spectrometer, measures levels of chemical elements and gases in the Martian atmosphere. In addition to methane, the instrument can record levels of water and carbon dioxide.
Nearly all the methane gas found in Earth’s atmosphere is produced by biological activity. It usually comes from animal and plant life. But it can also be formed by geological processes, such as interactions between rocks and water.
NASA said the increased methane was measured to be about 21 parts per billion by volume (ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the volume of air is methane.
It was not the first time Curiosity has found methane gas in the Martian atmosphere. About a year ago, NASA announced that Curiosity had discovered sharp seasonal increases in the gas.
This time, NASA said the measured methane gas level was clearly larger than any others observed in the past. NASA officials even temporarily stopped Curiosity’s other activities to investigate further.
“It's exciting because microbial life is an important source of methane on Earth,” NASA said in a statement announcing the discovery.
However, Curiosity’s team carried out a follow-up methane experiment that showed a sharp drop in levels of the gas. The second examination found the level was less than one part per billion by volume. That number was “close to the background levels Curiosity sees all the time,” NASA said.
The rise and fall of the methane gas levels left NASA scientists with more questions than answers. The scientists are continuing to study possible causes for the sudden increase.
"The methane mystery continues," said Ashwin Vasavada, Curiosity's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're more motivated than ever to keep measuring and put our brains together to figure out how methane behaves in the Martian atmosphere."
Curiosity does not have instruments that can exactly identify whether the source of the methane is biological or geological. One leading theory is that methane is being released from underground areas created by possible life forms that disappeared long ago.
Even though Mars has no active volcanoes, scientists believe it is also possible that methane is being produced by reactions involving carbon materials and water.
A clearer understanding of methane levels over time “could help scientists determine where they're located on Mars,” NASA said. Scientists hope this understanding will come as Curiosity continues to collect methane data in its search for possible life.
I’m Bryan Lynn.
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Words in This Story
mission – n. an important task, usually involving travel somewhere
geological – adj. relating to the study of rocks, soil and the physical structure of the Earth
volume – n. the number of amount of something
microbial – adj. relating to microbes (very small living things)
motivate – v. to cause someone to behave in a particular way
determine – v. to control or influence directly
locate – v. find or discover the exact position of something
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