A group of prominent american scientists, under protection of the National Research Council, considers viable the existence of alternating life (with small or, great biochemical differences) u, others variants non-based on metabolisms or structures bound to Carbon, biodisolvents (similar to water) or systems similar to earth molecular found buildings ; ideas and definitions suggested years back, by other scientists (life, is all semiopened material system, able to accumulate energy of the surroundings, to store it, to modify it, generating self-replicates of its structure with capacity or not, of random variability). The committee that advises first to look for early earth life forms in deserts, subsoil of marine bottoms), of our own planet, adds in: “The Limits of Organic Life in Planetary Systems”, published yesterday by the National Research Council: 1) Planets and moons exist, with water or, other biosolvents sign tracks: Hydrogen fluoride (H2F, although little), liquid NH3 or, formalin (able to dissolve substances to the interior of an organism). The NH3 or the CH4, has predisposition to act well in cold planets, feeding organisms with little energy of activation. The probe Huygens who visited Titan (2005), found CH4 bathing its surface, as well as mixtures of H2O-NH3 pouring from its interior. It matters not to hope to find similar life to ours. In as much the existence of great number of abundant active water geysers in Enceladus exists, this moon can lodge life. 2) Although our earth DNA uses Phosphorus (P), in their structure, the possibility exists of replacing it, with Arsenic :As (Adenosine tri-arsenite, instead ATP). 3) Although organic life is potentially easiest to build in the universe, the N (abundant in certain planets), can replace the C.
4) Single, non-metals (H, B, C, N, O, S, Si, P, S.As), can form long chains of great solidity, despite, to be later hidrolized. 5) By its smallness and great capacity of connection the H, is seen as an essential element in any form of exobiológic life. 6) Where S abounds, it can replace to O. 7) The C can be replaced by (Silicon: Si), that has 4 points for different connections, although by their greater size these unions will not be so stable. In prebiótic atmospheres nevertheless the emergency of SiH4 is possible. In silicon structures, the H can be replaced by carbon groups or alquilos, in cold. Unlike CO2, the SiO2 is a solid and not a gas which will complicate the metabolism. The SiO2 can form long chains adaptable warm up environments being possible to connect to these HC or FC. One does not hope that Si-Si structures exhibit great variety or manage to conform great chains and rings. The book exposes also the discrepancies of Dr. Michael Meyer, who thinks that astrobiólogists must be limit their search to forms of life based on C (abundant element in the Universe). 7) Although our earth DNA consists of 4 compound chemistries (nucleótides), some experiments in synthetic biology have managed to create structures with 6 or but nucleótides able to lodge genetic information and potentially to bear darwinian evolutions. 8) Certain chemical studies, that demonstrate that an organism can use alternating forms of energy (sodium hidroxide or, hydrochlorate acid), sustain the thesis of the possible existence of organisms with metabolisms non-based on C. 9) Most scientists, assumes that in early stages, life based on RNA existed, of a single chain. The present DNA could have eliminated these forms of life, by competition. Today, could exist life forms based on RNA in the subsurface of marine oceans or in extreme areas, says Dr. John A. Baross. 10) The scientists are urged to build new biodetectors able to locate life accurately (components of light, C, H, Or, C, P, As, S and organic Carbon). It would be tragic not to find life in planets, because astronauts will not be able to recognize it.