也许二氧化硫比磷化氢更可以解释金星上神秘的大气特征

也许二氧化硫比磷化氢更可以解释金星上神秘的大气特征

Last September, a cautious but exciting result was reported. Venus appears to have an abundance of phosphine in its clouds. Phosphine is mostly produced by living organisms so that certainly got people talking. In good science praxis, other scientists got involved to test if the finding was correct. Questions were asked and some problems with the data were found, leaving the mystery wide open.

去年9月，报道了一个谨慎但令人兴奋的结果。金星的云层中似乎有大量的磷化氢。磷化氢主要是由生物体产生的，这当然引起了人们的讨论。在良好的科学实践中，其他科学家也参与进来测试这个发现是否正确。人们提出了一些问题，也发现了一些数据上的问题，让这个谜团冲出了迷雾。

Now a different team has put forward evidence to solve this. It was never phosphine at all. It was the most-like but less-exciting sulfur dioxide. The new scenario is accepted for publication in The Astrophysical Journal and is currently available as a pre-print, which means it has not yet been peer-reviewed.

现在，一个不同的团队提出了解决这个问题的证据。根本就不是磷化氢。它是最像但不那么刺激的二氧化硫。这一新的设想将在《天体物理学杂志》上发表，目前是预印本，这意味着它还没有经过同行评审。

"Instead of phosphine in the clouds of Venus, the data are consistent with an alternative hypothesis: They were detecting sulfur dioxide," co-author Victoria Meadows, a UW professor of astronomy stated in the press release. "Sulfur dioxide is the third-most-common chemical compound in Venus' atmosphere, and it is not considered a sign of life."

“不是在金星的云层中发现了磷，数据与另一种假设一致:他们检测到了二氧化硫，”合著者维多利亚·梅多斯，华盛顿大学的天文学教授在新闻发布会上说。“二氧化硫是金星大气中第三常见的化合物，它不被认为是生命的迹象。”

Dr Alfredo Carpineti

Chemicals in outer space are discovered by looking at the emission of electromagnetic radiation at particular frequencies. These signatures can sometimes get confusing because our instruments are not perfect and this is why observations are followed up with other instruments to find more evidence to confirm detection.

通过观察特定频率的电磁辐射发射，可以发现外层空间的化学物质。这些信号有时会让人感到困惑，因为我们的仪器并不完美，这就是为什么观测之后会有其他仪器来寻找更多的证据来证实检测结果。

Let’s take a step back to the first detection of this signal. Back in 2017, the original research team used the James Clerk Maxwell Telescope (JCMT) and discovered a particular radio wave emission from the clouds of Venus. There were two molecules that would fit that signature. Phosphine and sulfur dioxide. The team decided to use the Atacama Large Millimeter/submillimeter Array (ALMA) to distinguish between the two. In that dataset (which we now know had other issues) they found that sulfur dioxide was not abundant enough, so they concluded that phosphine was likely the source of the original signal.

让我们回到第一次探测到这个信号的时候。早在2017年，最初的研究团队就使用了詹姆斯·克拉克·麦克斯韦望远镜(JCMT)，发现了金星云层中发出的一种特定的无线电波。有两个分子符合这个特征。膦和二氧化硫。该团队决定使用阿塔卡马大型毫米/亚毫米阵列(ALMA)来区分这两者。在那个数据集(我们现在知道有其他问题)中，他们发现二氧化硫不够多，因此他们得出结论，磷化氢可能是原始信号的来源。

The new work took a different approach. They modeled the atmosphere of Venus and used that to interpret what was seen and not seen in the data from the two telescopes. Their model indicates that the signals are not coming from the clouds of Venus but from 80 kilometers (50 miles) above them, in the mesosphere. Not a place where phosphine is likely to survive.

新工作采用了一种不同的方法。他们模拟了金星的大气层，并用它来解释这两个望远镜的数据中看到的和没有看到的东西。他们的模型表明，信号不是来自金星云层，而是来自云层上方80公里(50英里)的中间层。磷化氢不太可能在这里生存。

"Phosphine in the mesosphere is even more fragile than phosphine in Venus' clouds," explained Meadows. "If the JCMT signal were from phosphine in the mesosphere, then to account for the strength of the signal and the compound's sub-second lifetime at that altitude, phosphine would have to be delivered to the mesosphere at about 100 times the rate that oxygen is pumped into Earth's atmosphere by photosynthesis."

“中间层的磷化氢比金星云层中的磷化氢更脆弱，”梅多斯解释说。“如果JCMT的信号来自中间层的磷化氢，那么考虑到信号的强度和这种化合物在那个高度的亚秒寿命，磷化氢被输送到中间层的速度必须是地球通过光合作用输送到大气中的氧气速度的100倍。”

The other major find is that they think that the ALMA data most likely underestimated the amount of sulfur dioxide present in the Venus atmosphere, giving the false impression that the bulk of the JMCT signal was likely coming from phosphine.

另一个重要发现是，他们认为ALMA的数据很可能低估了金星大气中二氧化硫的含量，从而产生了大量JMCT信号可能来自磷化氢的错误印象。

"The antenna configuration of ALMA at the time of the 2019 observations has an undesirable side effect: The signals from gases that can be found nearly everywhere in Venus' atmosphere—like sulfur dioxide—give off weaker signals than gases distributed over a smaller scale," added co-author Alex Akins, a researcher at the Jet Propulsion Laboratory.

“ALMA在2019年观测时的天线配置有一个不良的副作用:来自金星大气中几乎无处不在的气体(比如二氧化硫)发出的信号比分布在较小范围内的气体发出的信号更弱，”喷气推进实验室的研究人员、共同作者亚历克斯·埃金斯补充道。

The original team is currently re-examining the whole data set, and we look forward to seeing what their analysis comes up with.

最初的团队目前正在重新检查整个数据集，我们期待看到他们的分析结果。