Life Beyond Earth: The Search for Habitable Worlds in the Universe

Life Beyond Earth: The Search for Habitable Worlds in the Universe

Athena Coustenis, Thérèse Encrenaz

Language: English

Pages: 296


Format: PDF / Kindle (mobi) / ePub

What is life and where can it exist? What searches are being made to identify conditions for life on other worlds? If extraterrestrial inhabited worlds are found, how can we explore them? In this book, two leading astrophysicists provide an engaging account of where we stand in our quest for habitable environments, in the Solar System and beyond. Starting from basic concepts, the narrative builds scientifically, including more in-depth material as boxed additions to the main text. The authors recount fascinating recent discoveries from space missions and observations using ground-based telescopes, of possible life-related artefacts in Martian meteorites, extrasolar planets, and subsurface oceans on Europa, Titan and Enceladus. They also provide a forward look to future missions. This is an exciting, informative read for anyone interested in the search for habitable and inhabited planets, and an excellent primer for students in astrobiology, habitability, planetary science and astronomy.

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P t a n d c o n d i t i o n s o f l i f e 45 But the chirality concept is still an excellent tool for distinguishing between a biological and a non-biological origin of some species. Enzymes made up of all d-amino acids function just as well as those made up of only l-amino acids, but the two enzymes react with the opposite stereoisomeric substrates (reactants that are identical in atomic constitution and bonding, but different in the threedimensional spatial arrangement of their atoms). There.

Adverse effects such as damaging tidal forces and solar flares. Even if life originated on such a planet, it would evolve differently from Earth, as the atmosphere and in some cases magnetospheres would experience extreme long-term stellar radiation and plasma exposures. Thus, a combination of stellar and geophysical conditions can prohibit the existence of life on planets within the HZ. Space weather, in particular stellar radiation and stellar variation, can significantly affect the ability of.

Question is whether favourable conditions persist long enough to allow for life to develop and evolve after it gets started, the question for the Class III and Class IV habitats is more whether life could start at all, as we shall see in Chapter 4. Nevertheless, icy moons in the Solar System and exoplanets may host the right ingredients for developing (today or in the past) lifefriendly conditions, so the interest in an astrobiological investigation of these planetary objects is enormous. Since.

History (with flooding by this water being responsible for the valley networks; Figure 3.13), while the presence of sulfates was associated with the temporary catastrophic flow of water in the more recent past, responsible for the outflow channels mentioned above. These results led to new insights in the quest for past forms of life: they have been and 102 t e r r e s t r i a l p l a n e t s a n d t h e i r d i v e r g i n g e v o l u t i o n s WATER MAP 2001 Mars Odyssey Gamma Ray Spectrometer.

Were interpreted as theoretical nanobacteria and fossilized forms of living organisms. However, no cellular life of this size has ever been observed on Earth; it was also pointed out that nanobacteria might be too small to contain RNA. Another comment was that the biomorphs observed in the meteorite might not originate from Mars, but might be the result of terrestrial contamination. In addition, amino acids and polycyclic aromatic hydrocarbons (PAHs) have been also found in the meteorite.

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