Alien Rainbow: Astrobiology Gets a New Spectrum of Life Signatures

An international collaboration by scientists has created a catalogue of signatures of life that astrobiologists could use to hunt for signs of habitation throughout the cosmos.

The signatures all come from simple organisms found on Earth that could have analogues elsewhere in space.

Lisa Kaltenegger from Cornell University’s Institute for Pale Blue Dots said, “This database gives us the first glimpse at what diverse worlds out there could look like. We looked at a broad set of life forms, including some from the most extreme parts of Earth.”

The NASA Ames Research Center was heavily involved in the project, which has been described in a paper entitled “Surface Biosignatures of Exo-Earths: Remote Detection of Extraterrestrial Life.”

If any of the organisms included in the database were dominant on another world, their pigmentations in the atmosphere could be used to identify those worlds as having life, as well as to identify what kind of life it might be.

As it is explained in the paper, “Much of the history of life on Earth has been dominated by microbial life. It is likely that life on exoplanets evolves through single-celled stages prior to multicellular creatures. Here, we present the first database for a diverse range of life — including extremophiles (organisms living in extreme conditions) found in the most inhospitable environments on Earth — for such surface features in preparation for the next generation of telescopes that will search for a wide variety of life on exoplanets.”

The amazing array of life signatures that could be remote-detected on exoplanets spans 137 cellular organisms and can be found here: http://biosignatures.astro.cornell.edu

It is hoped that the catalogue of organisms, which includes extremophiles from some of Earth’s harshest environments, could be useful in the search for extraterrestrial life, and that it could help to answer the question that has been with humanity since we first gazed at the stars and wondered, “Are we alone?” Image credit and original press release: https://cornell.box.com/exoearths

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Stolen Oceans: Mars Lost its Water to Space

A new paper published by the journal Science has mapped out just how much water Mars lost from its early atmosphere.

About half of the red planet's northern hemisphere would have been cloaked in an ocean around 4 billion years ago, according to Geronimo Villanueva from NASA’s Goddard Space Flight Center. Lead author of the paper, Villanueva stated in a press release for ESO:

“Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space. With this work, we can better understand the history of water on Mars.” 

Two different forms of water were studied using ESO's imaginatively named Very Large Telescope and a number of other instruments: our familiar water (H₂O) and semi-heavy water (HDO). By examining the ratio between these two types of water over a period of 6 Earth years, the team was able to calculate exactly how much water may have been lost from Mars' surface.

The conclusion? About the same amount that's in the Earth's Arctic Ocean.

Second author on the paper, Michael Mumma, said, “With Mars losing that much water, the planet was very likely wet for a longer period of time than previously thought, suggesting the planet might have been habitable for longer.”

Indeed, the lost ocean on Mars would have covered more of the red planet's surface (19%) than our own Atlantic Ocean does of Earth's (17%).

The finding underlines just how far modern astronomical technology has come. Co-author Ulli Kaeufl illustrated this, saying, "I am again overwhelmed by how much power there is in remote sensing on other planets using astronomical telescopes: we found an ancient ocean more than 100 million kilometres away!"

The study has major implications for astrobiologists; a more habitable ancient Mars means that there is an increased likelihood that we will find evidence of life on our neighbouring planet.

By Jon Fern
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Image: artswallpapers.net