Page 34 - september 2023

Ultimately, the presence of Phosphorus can
limit the primary production by marine life, Final Thoughts
thus making it the "limiting nutrient." Examining
whether the phosphorus cycle exists on every In summary, examining phosphorus as
planet may be impossible. However, the conclusion a factor in exoplanet habitability shows
that we can draw from here is that depending promise. The presence of phosphorus
upon the phosphorus present on the top surface alters exoplanet environments, providing
of a planet (soil, weathering rocks, etc.), it can be insights into their geology and potential
classified as potentially habitable, while the habitability. Phosphine gas, a potential
others can be rejected. biosignature, could provide hint at
extraterrestrial life. However, challenges
Recent studies show that ocean weathering- include distant phosphorus detection
instead of surface weathering- may also provide and limited data. Future research
sufficient concentration of Phosphorus in the should weigh specialised equipment
oceans in the waterworlds under certain condi- development costs, time, and required
tions. One may wonder what a waterworld is. expertise. This assessment will
Simply put, Waterworld is a planet with oceans- determine if the benefits of using
either surface or subsurface- covering a significant phosphorus as a constraint outweigh
portion of its lithosphere. Earth is also a water- the downsides. Advancements in this
world. field promise to deepen our knowledge
of exoplanets and the search for life
We can't detect liquid water on an exoplanet, beyond Earth.
so we use water vapour as an indicator. Before,
scientists believed waterworlds whose entire
surface is covered by oceans could not have
phosphorus and thus are not fit for life. However, sphere that indicates the presence of life on a celestial
new studies suggest otherwise. Researchers body- for example, water, carbon dioxide, methane
now believe that waterworlds can also have and others. No abiotic false positives on terrestrial
unique mechanisms to recycle phos- planets have been found for phosphine.
phorus and provide enough usable It can also be detected at no extra cost
phosphorus to sustain life. This has because its spectra lie in the same wave-
made us revisit the waterworlds. length as other critical atmospheric
molecules and biosignature gases.
Another importance of Phosphorus This makes phosphine an excellent
is that one of its compounds- Shreyan Deo biosignature gas. With the help of the
Phosphine (PH3)- is a biosignature gas Student, 12A latest technology of the James Webb
in an anoxic environment. A biosigna- DPS Telescope, detecting phosphine gas will
ture gas is a specific gas in an atmo- Vasant Kunj become easier.

References
NASA Exoplanet Exploration. Exoplanet Exploration: Planets Beyond our Solar System. Retrieved February 25, 2023, from https://exoplanets.nasa.gov/
Filippelli, G. M. (2002). The Global Phosphorus Cycle. https://www.researchgate.net/publication/236628350_The_Global_Phosphorus_Cycle
Filippelli, G. M. (2022). Phosphorus and Life on a Water World. https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2021GL097346
Grenfell, J. L. (2017). A Review of Exoplanetary Biosignatures. https://arxiv.org/pdf/1710.03976.pdf
Karl, D. M. (2000, July 6). Phosphorus, the staff of life. Macmillan Magazines Ltd. https://www.nature.com/articles/35017686.pdf
Seager, S. (2013). Exoplanet Habitability. http://www.chriscunnings.com/uploads/2/0/7/7/20773630/qualifications_of_habitability.pdf
Sousa-Silva, C., et al. (2020). Phosphine as a Biosignature Gas in Exoplanet Atmospheres. https://www.liebertpub.com/doi/pdf/10.1089/ast.2018.1954

32 xÉ<Ç =cÉxÉ flrEcj -2023