Scientists debate 'signs of life' on exoplanet K2-18b

One of humanity's oldest questions is: Are we alone in the universe? Illustration of planet K2-18b based on scientific data, published on September 11, 2023 - Photo: REUTERS

On April 17, Reuters News Agency published an interesting news: scientists from the University of Cambridge said that when using data from NASA's James Webb Space Telescope (JWST), they discovered traces of two chemical compounds, dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere of the exoplanet K2-18b.

On Earth, DMS is mainly produced by microorganisms, such as phytoplankton in the oceans, so it is considered a potential sign of life.

Controversial discovery

K2-18b also made headlines when it became the first exoplanet in its star's "habitable" zone where scientists detected carbon-containing organic molecules.

Astrophysicist Nikku Madhusudhan, who led the study, said the planet could be a "Hycean world" (a combination of hydrogen and ocean), with an ocean that could harbor life.

However, he also cautioned: "We need to be skeptical of our own results, because only by repeatedly testing them can we be confident in the finding."

Not long after, many scientists also expressed doubts about the research team's conclusions.

"The observations from JWST provide no real evidence that biosignatures like DMS or DMDS exist. If it were another planet, such a low signal level would be considered a non-detection at all," said Dr. Ryan MacDonald, an astrophysicist at the University of Michigan.

He also said that an independent research team was unable to reproduce similar results when it reanalyzed JWST data in 2023.

Professor Sara Seager (Massachusetts Institute of Technology), who was Mr Madhusudhan's research adviser, warned: "The current euphoria is outpacing the scientific evidence."

She said independent scientific groups currently have very different interpretations of the nature of the planet: some think it's a Hycean world, others think it's a molten magma ocean, an extremely harsh environment, and one even calls it a "mini Neptune."

'Signs of alien life' may be noise or error

NASA scientists say the discovery of a single biological signature cannot be considered evidence of life, and additional studies and similar lines of evidence are needed to draw a conclusion - Photo: NASA

According to scientists at the SETI Institute - an organization specializing in the research of extraterrestrial life and intelligence: "The chemical signal obtained is very vague, possibly just the result of noise or systematic error".

In addition, they also emphasize that there are abiotic sources that can produce compounds such as DMS, although rare and unstable, but cannot be ruled out.

Dr. Edward Schwieterman, an expert in exoplanet biology at the University of California Riverside, agrees: "The planetary context is the most important thing. If there are really those molecules in the atmosphere, we have to find other non-biological ways to explain them before we can say they are signs of life."

NASA also stated that the discovery of a single biological sign cannot be considered evidence of life, and that additional studies and similar lines of evidence are needed before a conclusion can be drawn.

Although there is still much controversy, scientists still recognize this as an important step forward in the journey to find life outside Earth. It helps guide further research and identify points that need to be clarified.

The search for life beyond Earth is one of humanity's greatest and most profound goals. But any claim of life out there needs to be thoroughly studied by the entire scientific community before it can be confirmed.

Read more Back to Topics

Back to topic

MINH HAI

Source: https://tuoitre.vn/khoa-hoc-tranh-cai-ve-dau-hieu-su-song-tren-ngoai-hanh-tinh-k2-18b-20250425155525456.htm