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 μm) portions of the electromagnetic spectrum and is made freely available on this website. 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 μm) 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.

Citing this biosignature catalogue: Hegde S., Paulino-Lima I. G., Kent R., Kaltenegger L., & Rothschild L., Surface biosignatures of exo-Earths: Remote detection of extraterrestrial life, Proceedings of the National Academy of Sciences of the United States of America (PNAS). March 2015, 112 (13) 3886-3891.

Online link to the article: Surface biosignatures of exo-Earths: Remote detection of extraterrestrial life.

Contact Information: Dr Siddharth Hegde; Email: sidworld at gmail dot com, shegde at astro.cornell.edu

Sample name	Description-files	Spectral-Plots	Data-files
Agrococcus sp._KM349956	Description	Spectral Plot	Data file
Alphaproteobacteria_KM349946	Description	Spectral Plot	Data file
Amphidinium carterae	Description	Spectral Plot	Data file
Anabaena sp. str. PCC 7120	Description	Spectral Plot	Data file
Anabaena sp. str. PCC 7120 with green fluorescent protein	Description	Spectral Plot	Data file
Arthrobacter sp._KM349883	Description	Spectral Plot	Data file
Arthrobacter sp._KM349893	Description	Spectral Plot	Data file
Arthrobacter sp._KM349898	Description	Spectral Plot	Data file
Arthrobacter sp._KM349916	Description	Spectral Plot	Data file
Arthrobacter sp._KM349918	Description	Spectral Plot	Data file
Arthrobacter sp._KM349919	Description	Spectral Plot	Data file
Arthrobacter sp._KM349921	Description	Spectral Plot	Data file
Arthrobacter sp._KM349924	Description	Spectral Plot	Data file
Arthrobacter sp._KM349938	Description	Spectral Plot	Data file
Arthrobacter sp._KM349939	Description	Spectral Plot	Data file
Arthrobacter sp._KM349943	Description	Spectral Plot	Data file
Arthrobacter sp._KM349958	Description	Spectral Plot	Data file
Azospirillum sp._KM349895	Description	Spectral Plot	Data file
Bacillales_KM349901	Description	Spectral Plot	Data file
Bacillales_KM349923	Description	Spectral Plot	Data file
Bacillales_KM349934	Description	Spectral Plot	Data file
Bacillales_KM349937	Description	Spectral Plot	Data file
Bacillales_KM349940	Description	Spectral Plot	Data file
Bacillus sp._KM349861	Description	Spectral Plot	Data file
Bacillus sp._KM349863	Description	Spectral Plot	Data file
Bacillus sp._KM349864	Description	Spectral Plot	Data file
Bacillus sp._KM349865	Description	Spectral Plot	Data file
Bacillus sp._KM349866	Description	Spectral Plot	Data file
Bacillus sp._KM349867	Description	Spectral Plot	Data file
Bacillus sp._KM349868	Description	Spectral Plot	Data file
Bacillus sp._KM349869	Description	Spectral Plot	Data file
Bacillus sp._KM349870	Description	Spectral Plot	Data file
Bacillus sp._KM349871	Description	Spectral Plot	Data file
Bacillus sp._KM349872	Description	Spectral Plot	Data file
Bacillus sp._KM349873	Description	Spectral Plot	Data file
Bacillus sp._KM349874	Description	Spectral Plot	Data file
Bacillus sp._KM349875	Description	Spectral Plot	Data file
Bacillus sp._KM349876	Description	Spectral Plot	Data file
Bacillus sp._KM349877	Description	Spectral Plot	Data file
Bacillus sp._KM349878	Description	Spectral Plot	Data file
Bacillus sp._KM349887	Description	Spectral Plot	Data file
Bacillus sp._KM349899	Description	Spectral Plot	Data file
Bacillus sp._KM349902	Description	Spectral Plot	Data file
Bacillus sp._KM349906	Description	Spectral Plot	Data file
Bacillus sp._KM349911	Description	Spectral Plot	Data file
Bacillus sp._KM349913	Description	Spectral Plot	Data file
Bacillus sp._KM349915	Description	Spectral Plot	Data file
Bacillus sp._KM349927	Description	Spectral Plot	Data file
Bacillus sp._KM349928	Description	Spectral Plot	Data file
Bacillus sp._KM349929	Description	Spectral Plot	Data file
Bacillus sp._KM349930	Description	Spectral Plot	Data file
Bacillus sp._KM349931	Description	Spectral Plot	Data file
Bacillus sp._KM349941	Description	Spectral Plot	Data file
Bacillus subtilis 168 plus chromogenic protein	Description	Spectral Plot	Data file
bacterium _KM349936	Description	Spectral Plot	Data file
bacterium _KM349950	Description	Spectral Plot	Data file
Basidiomycota sp._KM349879	Description	Spectral Plot	Data file
Betaproteobacteria_KM349948	Description	Spectral Plot	Data file
Calothrix parietina	Description	Spectral Plot	Data file
Cellulomonas sp._KM349959	Description	Spectral Plot	Data file
Chaetoceros gracilis	Description	Spectral Plot	Data file
Chaetoceros sp.	Description	Spectral Plot	Data file
Chlorella protothecoides	Description	Spectral Plot	Data file
Chlorellaceae_KM349944	Description	Spectral Plot	Data file
Chroococcidiopsis sp.	Description	Spectral Plot	Data file
Cryptomonas ovata	Description	Spectral Plot	Data file
Cyanidium caldarium	Description	Spectral Plot	Data file
Cyanophora biloba	Description	Spectral Plot	Data file
Cylindrotheca fusiformis	Description	Spectral Plot	Data file
Cytophagaceae_KM349914	Description	Spectral Plot	Data file
Deinococcus radiodurans	Description	Spectral Plot	Data file
Dermocarpa violacea	Description	Spectral Plot	Data file
Dunaliella salina	Description	Spectral Plot	Data file
Dunaliella sp.	Description	Spectral Plot	Data file
Ectocarpus siliculosus	Description	Spectral Plot	Data file
Ectothiorhodospira sp. str. BSL-9	Description	Spectral Plot	Data file
Escherichia coli	Description	Spectral Plot	Data file
Euglena gracilis var. saccharophila	Description	Spectral Plot	Data file
Firmicutes_KM349903	Description	Spectral Plot	Data file
Flavobacterium sp._KM349957	Description	Spectral Plot	Data file
Geodermatophilaceae_KM349892	Description	Spectral Plot	Data file
Geodermatophilus sp._KM349882	Description	Spectral Plot	Data file
Gloeocapsa sp.	Description	Spectral Plot	Data file
Haematococcus droebakensis	Description	Spectral Plot	Data file
Halorubrum chaoviator str. Halo-G*T_AM048786	Description	Spectral Plot	Data file
Hydrogenophaga sp._KM349947	Description	Spectral Plot	Data file
Hydrogenophaga sp._KM349962	Description	Spectral Plot	Data file
Hymenobacter sp._KM349884	Description	Spectral Plot	Data file
Isochrysis galbana	Description	Spectral Plot	Data file
Kocuria sp._KM349888	Description	Spectral Plot	Data file
Kocuria sp._KM349891	Description	Spectral Plot	Data file
Kocuria sp._KM349896	Description	Spectral Plot	Data file
Kocuria sp._KM349900	Description	Spectral Plot	Data file
Kocuria sp._KM349907	Description	Spectral Plot	Data file
Kocuria sp._KM349908	Description	Spectral Plot	Data file
Kocuria sp._KM349909	Description	Spectral Plot	Data file
Kocuria sp._KM349917	Description	Spectral Plot	Data file
Kocuria sp._KM349920	Description	Spectral Plot	Data file
Kocuria sp._KM349926	Description	Spectral Plot	Data file
Kocuria sp._KM349935	Description	Spectral Plot	Data file
Kocuria sp._KM349964	Description	Spectral Plot	Data file
Lyngbya purpurem	Description	Spectral Plot	Data file
Methylobacterium sp._KM349880	Description	Spectral Plot	Data file
Methylobacterium sp._KM349881	Description	Spectral Plot	Data file
Methylobacterium sp._KM349885	Description	Spectral Plot	Data file
Microbacterium sp._KM349942	Description	Spectral Plot	Data file
Micrococcaceae_KM349922	Description	Spectral Plot	Data file
Nannochloropsis oculata	Description	Spectral Plot	Data file
Nocardioides sp._KM349960	Description	Spectral Plot	Data file
Oocystis minuta	Description	Spectral Plot	Data file
Paracoccus sp._KM349912	Description	Spectral Plot	Data file
Pedobacter sp._KM349886	Description	Spectral Plot	Data file
Phormidium inundatum	Description	Spectral Plot	Data file
Phormidium sp.	Description	Spectral Plot	Data file
Planococcaceae_KM349897	Description	Spectral Plot	Data file
Planococcaceae_KM349910	Description	Spectral Plot	Data file
Planococcaceae_KM349932	Description	Spectral Plot	Data file
Planococcaceae_KM349933	Description	Spectral Plot	Data file
Planococcaceae_KM349955	Description	Spectral Plot	Data file
Planomicrobium sp._KM349904	Description	Spectral Plot	Data file
Pontibacter sp._KM349890	Description	Spectral Plot	Data file
Pontibacter sp._KM349894	Description	Spectral Plot	Data file
Porphyridium purpureum	Description	Spectral Plot	Data file
Prorocentrum micans	Description	Spectral Plot	Data file
Ramlibacter sp._KM349961	Description	Spectral Plot	Data file
Rhodococcus sp._KM349949	Description	Spectral Plot	Data file
Rhodosorus marinus	Description	Spectral Plot	Data file
Spirulina platensis	Description	Spectral Plot	Data file
Sporidiobolales_KM349951	Description	Spectral Plot	Data file
Sporidiobolales_KM349953	Description	Spectral Plot	Data file
Sporidiobolales_KM349954	Description	Spectral Plot	Data file
Sporosarcina sp._KM349905	Description	Spectral Plot	Data file
Streptomyces sp._KM349862	Description	Spectral Plot	Data file
Streptomyces sp._KM349965	Description	Spectral Plot	Data file
Synechococcus leopoliensis	Description	Spectral Plot	Data file
Synechococcus sp.	Description	Spectral Plot	Data file
Synechococcus sp. with reduced phycocyanin	Description	Spectral Plot	Data file