Life under a black sun

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(a) Projection system for interaction of a Lambertian radiator with the black hole. The arrows represent radiation from the cold surface at temperature Tc directed to the black hole. The remaining surface at temperature TH interacts by radiation (not shown) with the hot sky. (b) Scheme of the thermodynamic system: the planet covered with the light concentration systems shown in (a) accepts high-energy photons (long arrows) from space and sends low-energy photons (short arrows) to the black hole.

Life is dependent on the income of energy with low entropy and the disposal of energy with high entropy. On Earth, the low-entropy energy is provided by solar radiation and the high-entropy energy is disposed of as infrared radiation emitted into cold space. Here, we turn the situation around and imagine the cosmic background radiation as the low-entropy source of energy for a planet orbiting a black hole into which the high-entropy energy is expelled. We estimate the power that can be produced by thermodynamic processes on such a planet, with a particular interest in planets orbiting a fast rotating Kerr black hole as in the science fiction movie Interstellar. We also briefly discuss a reverse Dyson sphere absorbing cosmic background radiation from the outside and dumping waste energy to a black hole inside.
read more at http://aapt.scitation.org/doi/full/10.1119/1.4966905

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Eavesdropping on aliens

A small band in the sky has been identified in which extraterrestrial astronomers have good chances of discovering Earth

Narrow band: the image illustrates the transit zone, in which distant observers could see the Earth pass in front of the Sun. © Axel Quetz (MPIA) / Axel Mellinger, Central Michigan University

Narrow band: the image illustrates the transit zone, in which distant observers could see the Earth pass in front of the Sun.
© Axel Quetz (MPIA) / Axel Mellinger, Central Michigan University

Are we alone in the universe? To answer this question, astronomers have been using a variety of methods in the past decades to search for habitable planets and for the signals from extraterrestrial observers – to date, with no success. Maybe the search strategy has not been optimized until now, say researchers from the Max Planck Institute for Solar System Research in Göttingen and from McMaster University in Canada. They suggest that future searches focus on that part of the sky in which potential distant observers of the planetary system can notice the yearly transit of the Earth in front of the Sun. Continue reading Eavesdropping on aliens

Life ‘not as we know it’ possible on Saturn’s moon Titan

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States of acrylonitrile. (A) Azotosome. Interlocking nitrogen and hydrogen atoms reinforce the structure. (B) Solid. Adjacent nitrogen atoms create some unfavorable repulsion. (C) Micelle. Adjacent nitrogen atoms make this highly unfavorable. (D) Azotosome vesicle of diameter 90 Å, the size of a small virus particle.

Liquid water is a requirement for life on Earth. But in other, much colder worlds, life might exist beyond the bounds of water-based chemistry.

Taking a simultaneously imaginative and rigidly scientific view, Cornell chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world – specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells that metabolize, reproduce and do everything life on Earth does.

Their theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, is published in Science Advances, Feb. 27. The work is led by chemical molecular dynamics expert Paulette Clancy, the Samuel W. and Diane M. Bodman Professor of Chemical and Biomolecular Engineering, with first author James Stevenson, a graduate student in chemical engineering. The paper’s co-author is Jonathan Lunine, the David C. Duncan Professor in the Physical Sciences in the College of Arts and Sciences’ Department of Astronomy.

Membrane alternatives in worlds without oxygen: Creation of an azotosome“, , ,

Lunine is an expert on Saturn’s moons and an interdisciplinary scientist on the Cassini-Huygens mission that discovered methane-ethane seas on Titan. Intrigued by the possibilities of methane-based life on Titan, and armed with a grant from the Templeton Foundation to study non-aqueous life, Lunine sought assistance about a year ago from Cornell faculty with expertise in chemical modeling. Clancy, who had never met Lunine, offered to help. Continue reading Life ‘not as we know it’ possible on Saturn’s moon Titan

Where’s the Martian water? Evidence in meteorites on Earth indicates a Mars water reservoir

This illustration depicts Martian water reservoirs. Recent research provides evidence for the existence of a third reservoir that is intermediate in isotopic composition between the Red Planet’s mantle and its current atmosphere. These results support the hypothesis that a buried cryosphere accounts for a large part of the initial water budget of Mars. Image Credit: NASA

This illustration depicts Martian water reservoirs. Recent research provides evidence for the existence of a third reservoir that is intermediate in isotopic composition between the Red Planet’s mantle and its current atmosphere. These results support the hypothesis that a buried cryosphere accounts for a large part of the initial water budget of Mars.
Image Credit: NASA

NASA and an international team of planetary scientists have found evidence in meteorites on Earth that indicates Mars has a distinct and global reservoir of water or ice near its surface.
Though controversy still surrounds the origin, abundance and history of water on Mars, this discovery helps resolve the question of where the “missing Martian water” may have gone. Scientists continue to study the planet’s historical record, trying to understand the apparent shift from an early wet and warm climate to today’s dry and cool surface conditions.
The reservoir’s existence also may be a key to understanding climate history and the potential for life on Mars. The team’s findings are reported in the journal Earth and Planetary Science Letters. Continue reading Where’s the Martian water? Evidence in meteorites on Earth indicates a Mars water reservoir