NASA Scientists have discovered a molecule in Titan’s atmosphere that has never been found in any other atmosphere. In fact, many chemists may have hardly heard of it or don’t know how to pronounce it: cyclopropenyl or C3H2. Scientists say that this simple carbon-based molecule may be a precursor to more complex compounds that may form or provide possible life on Titan.
The researchers found that C3H2 By using a large millimeter/submillimeter array called Atacama located in northern Chile (Alma). They noticed C3H2It is made of carbon and hydrogen and screened by a series of unique light signals collected by a telescope; these reveal the chemical composition of energy emitted or absorbed by molecules in Titan’s atmosphere.
“When I realized I was looking at cyclopropenyl, my first thought was,’Well, this is really unexpected,” NASA’s Goddard Space Flight in Greenbelt, Maryland Conor Nixon, a planetary scientist at the center, said he led the ALMA search.His team’s findings were published on October 15, 2020 Acta Astronomy.
Although scientists discovered C3H2 In the pockets of the entire galaxy, it was a surprise to find it in the atmosphere. That’s because cyclopropenyl can easily contact with it and form other molecules of different species to react. So far, astronomers have discovered that C3H2 Only in the gas and dust clouds floating between star systems, in other words, areas that are too cold and too diffuse cannot promote many chemical reactions.
But a dense atmosphere like Titan is a nest of chemical activity. This is one of the main reasons scientists are interested in the moon, which is the destination of NASA’s upcoming dragonfly mission.Nixon’s team was able to identify small amounts of carbon3H2 The reason for being in Titan may be because they are looking at the upper layer of the moon’s atmosphere, where there is less other gas3H2 Interact with it. Scientists still don’t know why cyclopropene appears in Titan’s atmosphere, but no other atmosphere. Nixon said: “Titanium is unique in our solar system.” “It turns out that it is a treasure trove of new molecules.”
biggest SaturnTitan (Titan) is 62 satellites, in some respects the most similar to the earth we have discovered, this is a fascinating world. Unlike any other satellite in the solar system (there are more than 200), Titan’s atmosphere is four times denser than the earth’s atmosphere, plus clouds, rain, lakes and rivers, and even salty water.
Titan’s atmosphere is mainly composed of nitrogen, just like Earth’s, with a little methane. When methane and nitrogen molecules decompose under the strong light of the sun, their constituent atoms release a complex network of organic chemistry, which attracts scientists and makes the moon the top of NASA’s list of most important targets for the present or past living in the solar system in.
Rosaly Lopes, a senior research scientist and Titan expert at NASA’s Jet Propulsion Laboratory, said: “We are trying to determine whether Titan is suitable for living.”Joint police) In Pasadena, California. “So we want to know which compounds in the atmosphere reach the ground, and then whether that substance can reach the ocean below through the ice shell, because we think the ocean is where the habitable conditions are.
The types of molecules that may be on the surface of Titan may be the same as the types of molecules that form the basis of life on Earth. Scientists suspect that early in its history, between 380 and 2.5 billion years ago, when methane filled the earth’s air instead of oxygen, the situation here might be similar to today’s Titan.
NASA Goddard astrobiologist Melissa Trainer said: “We think Titan is a real laboratory. When we live here, we can see chemistry similar to the ancient earth. Matter.” The trainer is the deputy chief researcher of the Dragonfly mission and the person in charge of the instrument on the Dragonfly rotorcraft, which will analyze the composition of Titan’s surface.
“We will look for molecules larger than C3H2,” Trainer said, “but we need to understand what is happening in the atmosphere to understand the chemical reactions that cause complex organic molecules to form and descend to the surface.
Dragonfly is a NASA mission to explore the chemistry and habitability of Titan, Saturn’s largest moon.Image source: NASA’s Goddard Space Flight Center/Johns Hopkins University Applied Physics Laboratory
To date, cyclopropene is the only other “cyclic” or closed ring molecule found besides Titan’s atmosphere. Although C3H2 It is unknown to use it in modern biological reactions. Loop-closed molecules like this are important because they form the backbone of ribonucleobase. DNA, A complex chemical structure with the genetic code of life, and Ribonucleic acid, Is another important part of life function. “Their cyclic nature opens up this additional branch of chemistry, allowing you to build these biologically important molecules,” said Goddard Astrobiologist Alexander Tyron. He and Nixon searched for carbon atoms.3H2.
Scientists such as Thelen and Nixon are using large and highly sensitive Earth telescopes to find the simplest life-related carbon molecules that can be found in Titan’s atmosphere. Benzene is considered to be the smallest unit of complex, cyclic hydrocarbon molecules found in the atmosphere of any planet. But now, C3H2, Half of the benzene carbon atom seems to have replaced it.
Nixon’s team used the ALMA Observatory to observe at Titan in 2016. They were surprised to find a strange chemical fingerprint, which Nixon identified as a cyclopropenyl by searching a database of all known molecular light characteristics.
To reconfirm that the researchers are actually observing this unusual compound, Nixon carefully studied the research papers published in NASA Data Analysis. Cassini The spacecraft carried out 127 flights over the Titan between 2004 and 2017. He wanted to see if an instrument on the spacecraft could sniff out the chemicals around Saturn and Titan, and whether it could confirm his new results. (The instrument-called a mass spectrometer-collects hints of many mysterious molecules on Titan that scientists are still trying to identify.) Indeed, the Cassini has found evidence of a charged form of the same molecule C.3H3+.
Given that this is a rare discovery, scientists are trying to learn more about cyclopropene and how it interacts with gases in Titan’s atmosphere.
JPL planetary scientist Michael Malaska said: “This is a very strange small molecule, so it won’t be like what you learned in high school chemistry or even undergraduate chemistry.” The profession of learning it. “On Earth, this will not be what you are going to encounter.”
But, Marasca said, a molecule like C was found3H2 It’s very important to see the Titan’s panorama: “Every small part you can discover can help you put everything that happened into one huge puzzle.”
Reference: Conor A. Nixon, Alexander E. Thelen, Martin A. Cordiner, Zbigniew Kisiel, Steven B. Charnley, Edward M. Molter, Joseph Serigano, Patrick GJ Irwin, Nicholas A. “Using ALMA on Titan for Propylene Based detection”. Tienbi and Guan Yizhen (October 15, 2020), Acta Astronomy.
DOI: 10.3847 / 1538-3881 / abb679