也許二氧化硫比磷化氫更可以解釋金星上神秘的大氣特征

也許二氧化硫比磷化氫更可以解釋金星上神秘的大氣特征

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，報(bào)道了一個(gè)謹(jǐn)慎但令人興奮的結(jié)果。金星的云層中似乎有大量的磷化氫。磷化氫主要是由生物體產(chǎn)生的，這當(dāng)然引起了人們的討論。在良好的科學(xué)實(shí)踐中，其他科學(xué)家也參與進(jìn)來測(cè)試這個(gè)發(fā)現(xiàn)是否正確。人們提出了一些問題，也發(fā)現(xiàn)了一些數(shù)據(jù)上的問題，讓這個(gè)謎團(tuán)沖出了迷霧。

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is accepted for publication in The Astrophysical Journal and is currently available as a pre-print, which means it has not yet been peer-reviewed.

現(xiàn)在，一個(gè)不同的團(tuán)隊(duì)提出了解決這個(gè)問題的證據(jù)。根本就不是磷化氫。它是最像但不那么刺激的二氧化硫。這一新的設(shè)想將在《天體物理學(xué)雜志》上發(fā)表，目前是預(yù)印本，這意味著它還沒有經(jīng)過同行評(píng)審。

"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."

“不是在金星的云層中發(fā)現(xiàn)了磷，數(shù)據(jù)與另一種假設(shè)一致:他們檢測(cè)到了二氧化硫，”合著者維多利亞·梅多斯，華盛頓大學(xué)的天文學(xué)教授在新聞發(fā)布會(huì)上說。“二氧化硫是金星大氣中第三常見的化合物，它不被認(rèn)為是生命的跡象。”

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.

通過觀察特定頻率的電磁輻射發(fā)射，可以發(fā)現(xiàn)外層空間的化學(xué)物質(zhì)。這些信號(hào)有時(shí)會(huì)讓人感到困惑，因?yàn)槲覀兊膬x器并不完美，這就是為什么觀測(cè)之后會(huì)有其他儀器來尋找更多的證據(jù)來證實(shí)檢測(cè)結(jié)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.

讓我們回到第一次探測(cè)到這個(gè)信號(hào)的時(shí)候。早在2017年，最初的研究團(tuán)隊(duì)就使用了詹姆斯·克拉克·麥克斯韋望遠(yuǎn)鏡(JCMT)，發(fā)現(xiàn)了金星云層中發(fā)出的一種特定的無線電波。有兩個(gè)分子符合這個(gè)特征。膦和二氧化硫。該團(tuán)隊(duì)決定使用阿塔卡馬大型毫米/亞毫米陣列(ALMA)來區(qū)分這兩者。在那個(gè)數(shù)據(jù)集(我們現(xiàn)在知道有其他問題)中，他們發(fā)現(xiàn)二氧化硫不夠多，因此他們得出結(jié)論，磷化氫可能是原始信號(hào)的來源。

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.

新工作采用了一種不同的方法。他們模擬了金星的大氣層，并用它來解釋這兩個(gè)望遠(yuǎn)鏡的數(shù)據(jù)中看到的和沒有看到的東西。他們的模型表明，信號(hào)不是來自金星云層，而是來自云層上方80公里(50英里)的中間層。磷化氫不太可能在這里生存。

"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."

“中間層的磷化氫比金星云層中的磷化氫更脆弱，”梅多斯解釋說。“如果JCMT的信號(hào)來自中間層的磷化氫，那么考慮到信號(hào)的強(qiáng)度和這種化合物在那個(gè)高度的亞秒壽命，磷化氫被輸送到中間層的速度必須是地球通過光合作用輸送到大氣中的氧氣速度的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.

另一個(gè)重要發(fā)現(xiàn)是，他們認(rèn)為ALMA的數(shù)據(jù)很可能低估了金星大氣中二氧化硫的含量，從而產(chǎn)生了大量JMCT信號(hào)可能來自磷化氫的錯(cuò)誤印象。

"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年觀測(cè)時(shí)的天線配置有一個(gè)不良的副作用:來自金星大氣中幾乎無處不在的氣體(比如二氧化硫)發(fā)出的信號(hào)比分布在較小范圍內(nèi)的氣體發(fā)出的信號(hào)更弱，”噴氣推進(jìn)實(shí)驗(yàn)室的研究人員、共同作者亞歷克斯·埃金斯補(bǔ)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.

最初的團(tuán)隊(duì)目前正在重新檢查整個(gè)數(shù)據(jù)集，我們期待看到他們的分析結(jié)果。