Biological products in atmosphere may find alien life: Study says

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Representational Image
Representational Image

New Delhi : In a new study, scientists say that biological products in the atmospheres keep the potential to detect alien life in habitable planets outside our solar system.

Experts say these atmospheric fingerprints of life, called biosignatures, can be studied using next-generation telescopes that measure the composition of gases surrounding planets that are light years away. The statement has been mentioned as per the research published in Astrophysical Journal Letters. 

Conversly, biosignatures based on single measurements of atmospheric gases could be confusing.

Now, scientists at the University of California, Riverside (UCR) in the US are working on the first quantitative framework for dynamic biosignatures based on seasonal changes in the Earth’s atmosphere. 

As Earth revolves around the Sun, its designated axis for different regions receives more rays at different times of the year. 

The most visible signs of this phenomenon can be understood by studying the changes in the weather and length of the days. The kind of change has great impact in atmospheric composition.

 “Atmospheric seasonality is a promising biosignature because it is biologically modulated on Earth and is likely to occur on other inhabited worlds,” said Stephanie Olson from the University of California, Riverside (UCR).

“Inferring life based on seasonality would not require a detailed understanding of alien biochemistry because it arises as a biological response to seasonal changes in the environment, rather than as a consequence of a specific biological activity that might be unique to the Earth,” said Olson.

Further, extremely elliptical orbits could yield seasonality on extrasolar planets, or exoplanets, expanding the range of possible targets. 

Researchers gauged the opportunities and pitfalls associated with characterising the seasonal formation and destruction of oxygen, carbon dioxide, methane, and their detection using an imaging technique called spectroscopy. 

They modelled fluctuations of atmospheric oxygen on a life-bearing planet with low oxygen content, like that of Earth billions of years ago. 

The team found that ozone (O3), which is produced in the atmosphere through reactions involving oxygen gas (O2) produced by life, would be a more easily measurable marker for the seasonal variability in oxygen than O2 itself on weakly oxygenated planets.

“It’s really important that we accurately model these kinds of scenarios now, so the space and ground-based telescopes of the future can be designed to identify the most promising biosignatures,” said Edward Schwieterman, a NASA Postdoctoral Program fellow at UCR.

“In the case of ozone, we would need telescopes to include ultraviolet capabilities to easily detect it,” said Schwieterman.

He mentioned that the challenges in searching for life is the uncertainty of data collected from so far away. False positive which includes non-biological processes masquerade as life and false negative which talks about life on a planet produces few or no bio-signatures.

“Both oxygen and methane are promising biosignatures, but there are ways they can be produced without life,” Schwieterman said.