A new study indicates that last year James Webb was unable to find signs of life on planet K2-18b. However, scientists urge not to get upset about this, because this does not mean that we are alone in the universe.
Message about signs of life on K2-18b
Recent reports that NASA’s James Webb Space Telescope has detected signs of life on the distant planet K2-18b have understandably caused excitement. However, a new study casts doubt on this conclusion, and also sets a limit on the sensitivity of the instrument to gases of biogenic origin.
A study by scientists from University College Riverside, published in The Astrophysical Journal Letters, may disappoint enthusiasts of extraterrestrial life, but does not exclude the possibility of its discovery in the near future.
In 2023, there were tantalizing reports of the presence of biosignature gas in the atmosphere of planet K2-18b, which showed several signs indicating the possibility of life.
Earth-like exoplanets
Many exoplanets, that is, planets orbiting other stars, are not easy to compare with Earth. Their temperatures, atmospheres and climatic conditions do not allow us to imagine Earth-type life on them. However, K2-18b is somewhat different.
“This planet gets almost the same amount of solar radiation as Earth. And if atmosphere is removed as a factor, K2-18b has a temperature close to Earth’s, which is also an ideal situation in which to find life,” says UCR project researcher and author of the article Shang-Min Tsai. The atmosphere of this world consists mainly of hydrogen, unlike ours based on nitrogen. However, there is an assumption that K2-18b has aquatic oceans similar to those on Earth.
Last year, a team from Cambridge, using JWST, discovered methane and carbon dioxide in the atmosphere of K2-18b — other elements that may indicate signs of life.
Signs of life on planet K2-18b
“What was icing on the cake, in terms of the search for life, is that last year these researchers reported a tentative detection of dimethyl sulfide, or DMS, in the atmosphere of that planet, which is produced by ocean phytoplankton on Earth,” Tsai said.
Since the telescope’s data were inconclusive, the researchers wanted to understand whether enough dimethyl sulfide could accumulate to be detected on K2-18b, which is about 120 light-years from Earth. As on any other planet at this distance, it is impossible to obtain physical samples of atmospheric chemicals.
Telescope capabilities
Based on computer models that take into account the physics and chemistry of dimethyl sulfide, as well as a hydrogen-based atmosphere, the researchers found that it was unlikely that the data indicated the presence of this gas. “The signal strongly overlaps with methane, and we think that picking out DMS from methane is beyond this instrument’s capability,” Tsai said.
However, the researchers believe that dimethyl sulfide can accumulate to levels that can be detected. For this to happen, plankton or another life form must produce 20 times more DMS than is present on Earth.
Detecting life on exoplanets is a difficult task, given their distance from Earth. To find the DMS, the Webb Telescope will need an instrument capable of better detecting infrared waves in the atmosphere than the one used last year. Fortunately, the telescope will use such an instrument later this year, which will allow us to definitively find out whether dimethyl sulfide exists on K2-18b.
According to phys.org
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