life-on-venus-the-significance-of-the-discovery-of-phosphine-gas-th

Context: An announcement by an international team of astronomers about the discovery of phosphine gas in the atmosphere of Venus recently triggered global excitement about the possibility of the presence of lifeforms on the neighbouring planet. 

  • Apart from being produced in industrial processes, phosphine, a colourless but smelly gas, is known to be made only by some species of bacteria that survive in the absence of oxygen.

Analysis

  • Venus, the hottest planet in the solar system, has not enjoyed as much recent attention as Mars, as far as space missions are concerned. 
  • With surface temperatures of above 460° Celsius that can melt even a metal like lead, and a heavy atmosphere of carbon dioxide, the planet was considered hostile to life.
  • This despite its being similar in size to the Earth and rocky, so much so that it is often called the Earth’s “sister planet”. 
  • There was some excitement when the European Space Agency’s mission, Venus Express, found signs of ozone, made of three oxygen atoms and considered a biomarker, in the upper atmosphere of Venus, in 2011. 
  • But the recent discovery of traces of another biomarker phosphine— which on Earth is associated with living organisms, in its atmosphere has just given the search for extraterrestrial life a shot in the arm. 
  • Phosphine, a compound of one phosphorous atom and three hydrogen atoms, is a flammable gas that on Earth occurs from the breakdown of organic matter by some microbes. 
  • Phosphine is known to be produced only through biological process, and not through any naturally occurring chemical process. 
  • There are some other ways in which this chemical might be produced, for example, in the underbelly of volcanoes or meteorite activity, but that would have shown in much lower concentrations. 
  • Scientists say it is more significant, for example, than the discovery of water on the Moon or Mars. 
  • Water is only circumstantially related to life. It is not produced by life. Phosphine is produced by biological processes. In this way, it is bigger than evidence for water.
  • Writing in Nature Astronomy, the team stressed that the presence of phosphine alone did not prove the presence of life on Venus.
  • In an atmosphere rich in carbon dioxide, it is likely to get destroyed soon. 
  • However, the researchers estimate that phosphine forms about 20 parts per billion of Venus’s atmosphere. 
  • Phosphine was first identified in Venus’s atmosphere in 2017, using the James Clerk Maxwell Telescope in Hawaii. 
  • Further study and precise observations using the Atacama Large Millimeter/sub-millimeter Array facility in Chile confirmed the suspicions of the researchers in 2019. 
  • This can now only be taken further by making in situ measurements in the atmosphere of Venus. This poses its own challenges. 
  • Apart from the high surface temperature and dense atmosphere, the presence of sulphuric acid in the atmosphere of Venus makes it a highly corrosive environment. 
  • Perhaps flying at a height and sending down drones or balloons would be more feasible than a landing. 
  • Missions to Venus have been planned by NASA and ISRO (Shukrayaan). 
  • While NASA’s mission is slated for launch next year, ISRO is looking at 2023 right now.