Can someone please explain what paragraph is telling me? \"Exoplanet discovery h
ID: 58644 • Letter: C
Question
Can someone please explain what paragraph is telling me?
"Exoplanet discovery has made remarkable progress, with the first rocky planets having been detected in the central star’s liquid water habitable zone. The remote sensing techniques used to characterize such planets for potential habitability and life rely solely on our understanding of life on Earth. The vegetation red edge from terrestrial land plants is often used as a direct signature of life, but it occupies only a small niche in the environmental parameter space that binds life on present-day Earth and has been widespread for only about 460 My. To more fully exploit the diversity of the one example of life known, we measured the spectral characteristics of 137 microorganisms containing a range of pigments, including ones isolated from Earth’s most extreme environments. Our database covers the visible and near-infrared to the short-wavelength infrared (0.35–2.5 m) portions of the electromagnetic spectrum and is made freely available from biosignatures. astro.cornell.edu. Our results show how the reflectance properties are dominated by the absorption of light by pigments in the visible portion and by strong absorptions by the cellular water of hydration in the infrared (up to 2.5 m) portion of the spectrum. Our spectral library provides a broader and more realistic guide based on Earth life for the search for surface features of extraterrestrial life. The library, when used as inputs for modeling disk-integrated spectra of exoplanets, in preparation for the next generation of space- and ground-based instruments, will increase the chances of detecting life."
Explanation / Answer
Previous studies have shown that how spectral properties of land plants (because of pigmentation) can be used as biosignaturse to explore life on other planets or exoplanets. However, there is a limition to this biosignature because of the fact that land plants occupy a small niche in the environmental parameter space. According to the theory of evolution life evolved fom simple molecules and the first living forms were unicellular organisms known as prokaryotes. Interestingly, microbes are very diverse not only in number but also in pigmentation.The authors in this paper have exploited the spectral properties of diverse microbes (microbes living in extreme and non-extreme conditions; ranging from earths surface to upper atmosphere) in spectral range of 0.35 to 2.5 m (near infrared region of spectum) as a biosignature to find life on exoplanets. This region has strong absorption owing to the presence of water vapor in the atmosphere (which is marker of life). The reflection spectra of microbes in the near-infrared (up to 2.5 m) portion are thought to have absorption features unique to life owing to their water of hydration and biomolecular components. It was observed that within this range the microbes could be diversely characterized, primarily owing to pigmentation. Moreover, the absorption features of microorganisms owing to their water of hydration are seen to occur near 0.95, 1.15, 1.45, and 1.92 m. This implies that all carbon-based organisms irrespective of their functionality or hardiness will look quite similar in the infrared portion of the reflectance spectrum. This feature in the infrared up to 2.5 m may be a unique biosignature of life on potentially habitable planets. The authors here have assembled a digital spectral library containing 137 microorganisms to support imaging photometric and spectroscopic studies for potential habitability of rocky extrasolar planets in the habitable zone of the central star.