Role of Biology in Discovering Life on Exoplanets.

“Mankind Was Born on Earth. It Was Never Meant to Die Here.” [1]

For a long time now, humans have been searching to answer the two timeless questions: Where have we come from? Are we alone?

An exploration that started more as a curiosity to discover extraterrestrial life is slowly becoming more of a necessity for the survival of humankind. “If greenhouse gas emissions continue unabated, land temperatures will rise so substantially that large areas of Earth will become inhabitable.” [2] With the rise in population and reduction of inhabitable land, the necessity for finding another Earth increases vastly.

Astrobiology is the key to solve these issues. “It is an interdisciplinary scientific field that studies the origins, early evolution, distribution, and future of life in the universe. In addition, astrobiology considers the question of whether extraterrestrial life exists, and if it does, how humans can detect it.” [3]

The major Biology fields that come under astrobiology are molecular biology, biophysics, biochemistry, and biotechnology, encompassing the combination of the other three fields and integrating technology. The research primarily focuses on the origin of organic compounds, carbon-water-rock combination, planetary habitability, abiogenesis on Earth, research on biosignatures for life detection, and studies on the potential for life adaption to challenges on Earth and in outer space.

PLANETARY HABITABILITY

For a planet to be habitable, it is necessary that the planet lies in a ‘Habitable Zone.’

Though life may potentially exist in a different form around the universe to explore its existence, we first need to try finding life similar to that found on Earth. To do so, the factors of interest are those that have sustained multicellular life on Earth and not the ones that sustained unicellular life.

Habitable Zone is the distance from a star where water can exist in the liquid form. These zones have the potential to host life. “In its astrobiology roadmap, NASA has defined the principal habitability criteria as “extended regions of liquid water, conditions favorable for the assembly of complex organic molecules, and energy sources to sustain metabolism. “[4]

The discovery of extremophiles, organisms that can survive in extreme conditions, by biologists broadened the possibility of the existence of extraterrestrial habitats. Research on their existence, environments, and evolutionary pathways can help identify the evolution of life in the universe elsewhere.

ABIOGENESIS AND BIOCHEMISTRY

Abiogenesis is an evolutionary process by which life came into existence from non-living matter, such as simple organic and inorganic compounds. Most of the details of the process are still unknown, and scientists are still researching the multiprocess that leads to the formation of the cell. The primary aim of the study is to gain information on how the pre-life chemical reactions gave rise to life. If we can dig out the ‘How?’ of the question, it could be of great help in synthesizing life on habitable planets using the non-living matter present on them.

“The NASA states that it is necessary to identify interactions, intermediary structures and functions, energy sources, and environmental factors that contributed to the diversity, selection, and replication of evolvable macromolecular systems. Emphasis to map the advent of polymers that could replicate, store genetic information, and exhibit properties subject to selection was a critical step in the emergence of prebiotic chemical evolution.”[6]

According to a study by Carl Zimmer, the chemical condition for RNA production on Mars may have been better than those on Earth, attracting the research work for finding life on Mars.

Biochemistry is the study of chemical processes related to living organisms. It primarily deals with the interactions of macromolecules and their functions. It is concentrated in the fields of structural biology, enzymology, and metabolism. In addition, the study of extremophiles is conducted using biochemistry itself.

Biochemistry gives a fair idea of biosignatures of life; on a broad level, a planet with oxygen alongside methane indicates life’s presence. Life requires various molecular structures made up of simple building blocks. For a long time, there has been no clue how these building blocks developed on the early Earth surface. But in recent research, it has been found that “ shining ultraviolet light on hydrogen cyanide in water, along with a negatively charged ion such as bisulfite, leads to simple sugars. In certain environments, with the right conditions, hydrogen cyanide and a negatively charged ion can lead to the formation of many of life’s building blocks selectively and at large concentration.” [7] With such discoveries, Biochemistry serves a significant role in astrobiology.

BIOTECHNOLOGY

Most of the research conducted in astrobiology requires advanced biotechnological tools; without these, such remarkable exploration has never been possible. Along with that, upgrading the research around life on exoplanets in the future requires building a permanent presence of the astronauts on ISS and making long-duration missions possible. To facilitate that, NASA has been trying to develop new ways to manufacture medicines, build habitats, and more in space itself using biotechnology. The research focuses on

1. “get microorganisms to produce vital nutrients like those usually found in vegetables.” [8] which would eventually help in supplying the food and nutrients for multiple years at once.

2. “ to simplify the process of turning the plant into medicine (i.e., how to make it compact and portable).” [8] which would help develop medicines in space itself, helping astronauts survive and remain healthy for longer missions, making it more comfortable to work and thus speeding up the research. “One of the medicine is developed by genetically altering lettuce to produce parathyroid hormone. This hormone is an approved drug for treating osteoporosis, a common condition where bones become weak and brittle.” [8]

3. “prototyping technologies that could “grow” habitats on the Moon, Mars, and beyond out of life — specifically, fungi and the unseen underground threads that make up the main part of the fungus. With the right conditions, they can be coaxed into making new structures — like to the building blocks for a planetary home.” [8] this would help in the development of habitat on a surface other than Earth without harming the external environment

4. “using microorganisms to feed on waste processing their preferred form of nourishment generates products that can serve as raw materials used to make essential supplies like nutrients, medicines, plastic, and fuel.” [8] which would eventually help in the reuse of waste material and thus avoiding the need to bring it back to Earth

Along with all this, projects are running to differentiate between the habitable exoplanets and non-habitable exoplanets by studying the components of the wavelength of light collected from them. There are numerous applications of biotechnology supporting the biology aspects and the fundamental research on the discovery of life on exoplanets.

CONCLUSION

The above image lists the potentially habitable exoplanets found till 2020. However, there is yet a lot to explore. Still, it’s just a matter of a few hundred years after which there seems to be a strong possibility of discovery and confirmation of life on exoplanets, which would eventually boost the research to develop technology to create a habitat there and extend the existence of humankind in this universe. Biology has a significant contribution towards these explorations, and this is the role that biology plays in the discovery of life on other planets.

REFERENCES

1. Dialogue from the movie “Interstellar (2014).”

2. https://earthsky.org/earth/global-warming-areas-of-earth-too-hot-for-people/

3. “About Astrobiology.” NASA Astrobiology Institute. NASA. 21 January 2008. Archived from the original on 11 October 2008. Retrieved 20 October 2008.

4. ^ Kaufman, Marc. “A History of Astrobiology.” NASA. Retrieved 14 February 2019.

5. “Goal 1: Understand the nature and distribution of habitable environments in the Universe”. Astrobiology: Roadmap. NASA. Archived from the original on 17 January 2011. Retrieved 11 August 2007

6. “NASA Astrobiology Strategy” (PDF). NASA. 2015. Archived from the original (PDF) on 22 December 2016. Retrieved 24 September 2017.

7. https://theconversation.com/exoplanets-how-we-used-chemistry-to-identify-the-worlds-most-likely-to-host-life-100897

8. https://gameon.nasa.gov/2020/01/30/how-is-biotechnology-preparing-us-to-live-on-the-moon-and-mars/

BIBLIOGRAPHY

1. Dialogue from the movie “Interstellar (2014).”

2. https://earthsky.org/earth/global-warming-areas-of-earth-too-hot-for-people/

3. “About Astrobiology.” NASA Astrobiology Institute. NASA. 21 January 2008. Archived from the original on 11 October 2008. Retrieved 20 October 2008.

4. ^ Kaufman, Marc. “A History of Astrobiology.” NASA. Retrieved 14 February 2019.

5. “Goal 1: Understand the nature and distribution of habitable environments in the Universe”. Astrobiology: Roadmap. NASA. Archived from the original on 17 January 2011. Retrieved 11 August 2007

6. “NASA Astrobiology Strategy” (PDF). NASA. 2015. Archived from the original (PDF) on 22 December 2016. Retrieved 24 September 2017.

7. https://theconversation.com/exoplanets-how-we-used-chemistry-to-identify-the-worlds-most-likely-to-host-life-100897

8. https://gameon.nasa.gov/2020/01/30/how-is-biotechnology-preparing-us-to-live-on-the-moon-and-mars/

9. https://www.genengnews.com/insights/biotechnology-instruments-being-used-to-detect-alien-life/

10. https://www.scientificamerican.com/article/new-biomarkers-honed-help-search-for-life-earthlike-exoplanets/

11. https://exoplanets.nasa.gov/search-for-life/habitable-zone/

12. https://www.lpi.usra.edu/education/explore/our_place/hab_ref_table.pdf

13. https://en.wikipedia.org/wiki/Planetary_habitability

14. https://en.wikipedia.org/wiki/Extremophile

15. https://en.wikipedia.org/wiki/Abiogenesis

https://en.wikipedia.org/wiki/Astrobiology

UG Student, Birla Institute of Technology and Science, Pilani