Our search for life beyond Earth is still in its infancy. We\u2019re focused on Mars and, to a lesser extent, ocean moons like Jupiter\u2019s Europa and Saturn\u2019s Enceladus. Should we extend our search to cover more unlikely places like molecular clouds?<\/p>\n
<\/p>\n The idea that life could survive on other worlds like Mars or Europa gained vigour in the last few decades. Scientists found Earth life persisting in some extreme environments: hydrothermal vents, Antarctic pack ice, alkaline lakes, and even inside nuclear reactors. <\/p>\n Parallel to these discoveries, astronomers found life\u2019s chemical building blocks in space. They\u2019ve found amino acids inside meteorites, organic chemistry in the interstellar medium (ISM,) and polycyclic aromatic hydrocarbons (PAHs) in molecular clouds. <\/p>\n The discovery of extremophiles and life\u2019s building block in space suggests we should widen the scope of our search for life. Should molecular clouds be one of our targets? <\/p>\n Molecular clouds are massive clouds of gas and dust out of which stars form. They\u2019re called molecular clouds because they\u2019re mostly molecular hydrogen, though they can contain many different compounds. Though the clouds are filamentary in nature, they do form clumps of greater density that sometimes become stars. <\/p>\n Could life exist in such a tenuous environment? One researcher thinks the question is worth exploring. In a paper titled \u201cPossibilities for Methanogenic and Acetogenic Life in a Molecular Cloud,\u201d Chinese researcher Lei Feng examines the idea that life began in space as methanogens or acetogens, bacteria that produce methane and acetic acid as byproducts. These could be the precursors to Earth\u2019s life, according to Feng. <\/p>\n \u201cIf methanogenic life exists in the presolar nebula, then it may be the ancestor of Earth\u2019s life, and there are already some tentative evidences by several molecular biology studies,\u201d Feng writes. (English is clearly not Feng\u2019s first language, but it\u2019s easy to see what he\u2019s getting at.) <\/p>\n Feng\u2019s exploration rests on the idea of panspermia. Panspermia is the idea that life exists throughout the Universe and was spread around by asteroids, comets, even space dust and minor planets. The history of life on Earth suggests that panspermia could\u2019ve played a role, but we just don\u2019t know. The idea was entirely speculative until scientists started finding life\u2019s building blocks in space. <\/p>\n The main problem with life in molecular clouds concerns the temperature. It can be as low as 10 Kelvin or -263 Celsius. That\u2019s extremely cold, even for Earth\u2019s extremophiles. There\u2019s also no solid surface, but that might not be enough to prohibit life. <\/p>\n A key factor in life, as far as we understand it, is that cells need liquid to go about their metabolic business. Without water, cell membranes would lack structure, so there\u2019d be no way to keep the inside parts in and the outside stuff out. But does the liquid have to be water? Could it be liquid hydrogen? Methane? We don\u2019t know.<\/p>\n \u201cHydrogen molecules maintain a liquid state between 13.99 K and 20.27 K, and it happens to be the typical temperature of molecular clouds,\u201d Feng writes. \u201cIf we suppose that life in molecular clouds has a cell-like membrane structure and the hydrogen molecules (the main component of molecular clouds) Feng explains that liquid hydrogen in molecular cloud life (MCL) could play the same role that water plays in Earth life. \u201cA liquid hydrogen state is an ideal place for biochemical reactions similar to the water environment of cells on Earth,\u201d he states.<\/p>\n Life needs energy, too, and Earth life is almost entirely based on sunlight. Molecular clouds can be cold, dark places. How would Feng\u2019s MCL acquire energy?<\/p>\n \u201cHow does molecular cloud life obtain enough energy? Previously, the author proposed cosmic-ray-driven bioenergetics powered by the ionization of hydrogen molecules,\u201d Feng writes, referring to his previous paper on the same subject. There may be other possibilities. <\/p>\n Life and reproduction require energy transformation. Earth life relies on respiration. The respiration can be either aerobic or anaerobic, meaning it either uses oxygen or another electron acceptor. <\/p>\n Methanogenic bacteria were some of Earth\u2019s first life, and they produce methane as a byproduct in hypoxic (low oxygen) conditions. In the process, they generate free energy needed for life. Scientists have wondered if methanogens could live on Saturn\u2019s moon Titan. Could it be surviving in molecular clouds?<\/p>\n \u201cMethanogens could live on Titan, then can they live in molecular clouds? Here we will discuss such probability and calculate the releases of free energy for methanogenic life in the environment of molecular clouds,\u201d Feng writes.<\/p>\n According to Feng, the calculations show that methanogenesis in molecular clouds can produce enough free energy to fuel life. \u201cFrom the calculations, we found that the reaction of carbon monoxide, carbon These activities could even produce biosignatures, according to the author. \u201cThe consumption of carbon compounds by life activities may affect the distribution of organic molecules. It might be a possible trace signal of molecular cloud life,\u201d he writes.<\/p>\n Feng\u2019s hypothesis is that life could\u2019ve begun in molecular clouds and spread to Earth and elsewhere. He says that methanogenic and acetogenic life could be the ancestors of Earth\u2019s LUCA, the Last Universal Common Ancestor. LUCA is the common ancestral cell from which life\u2019s three domains, Bacteria, the Archaea, and the Eukarya, originated.<\/p>\n It never pays to discard an idea too hastily. There\u2019s a lot we don\u2019t know about Life, the Universe, and Everything. Can we afford to rule Feng\u2019s idea out? Unfortunately for Feng, his work lacks the participation of other researchers, which can be a signal that something\u2019s not quite right. Some single-author papers have made important contributions to science, mostly in the past. But they\u2019re becoming increasingly rare. <\/p>\n Feng\u2019s hypothesis is an interesting, outside-the-box idea. Outside-the-box thinking doesn\u2019t always lead directly to a new understanding, but it can spur new pathways of thinking. However, Feng\u2019s work runs into some roadblocks. Molecular clouds only last about 100 million years. Is that enough time? Also, LUCA is still just a hypothetical organism. <\/p>\n For now, Feng\u2019s paper is in pre-print, meaning it hasn\u2019t undergone peer review and hasn\u2019t been accepted for publication anywhere. It\u2019s hard to say what the wider scientific community will have to say about it.<\/p>\n Once it\u2019s published, we\u2019ll find out. <\/p>\n![\"\"](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2010\/11\/panspermia_big1.jpg\")
enriched therein, the hydrogen pressure is also enlarged, and hydrogen could maintain a liquid state in molecular cloud life.\u201d<\/p>\n![\"This](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2022\/02\/hubble_cha1_mosiac-1024x821.jpg\")
![\"Some](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2021\/11\/titan-1024x1024.jpg\")
dioxide or acetylene with hydrogen molecules releases sufficient Gibbs free energy to ensure the survival of molecular cloud life,\u201d Feng explains. <\/p>\nLike this:<\/h3>\n