αναμένεται να ξεκινήσει σήμερα το Perseverance rover, σε μια αποστολή αναζήτησης
σημαδιών ζωής στον Άρη.
συνοδεύεται επίσης από το Ingenuity, το πρώτο διαπλανητικό ελικόπτερο. Οι
προσπάθειες να ξεκινήσει το πρώτο ελικόπτερο στον Άρη υπάρχουν ήδη στο YouTube…
θα χρησιμοποιήσει μια εξελιγμένη σειρά επιστημονικών οργάνων για να εξετάσει το
κλίμα και την σύσταση του πλανήτη.
θα δει και θα σαρώσει τον ορίζοντα, θα ακούσει τον πλανήτη με μικρόφωνα στην επιφάνεια
για πρώτη φορά, θα τον νιώσει καθώς θα πάρει δείγματα “κρυμμένης μνήμης”, ίσως
ακόμη και να τον δοκιμάσει», είπε ο Thomas Zurbuchen της NASA.
να συγκεντρώσει ενδείξεις, ότι μπορεί να υπάρχουν ή να υπήρχαν κάποτε ζωντανοί οργανισμοί
στον Άρη – ΠΕΡΙΣΣΟΤΕΡΑ περί ΕΞΩΓΗΙΝΗΣ ΖΩΗΣ, ΕΔΩ. Αλλά επειδή δεν έχει την δυνατότητα να στείλει δείγματα στην Γη, θα
πρέπει να περιμένουμε μια αποστολή του 2026, για να συλλέξουμε τα ευρήματά του…
Όλα αυτά, ενώ ένας αστροφυσικός διερευνά την πιθανότητα ζωής κάτω από την επιφάνεια του Άρη… Μια νέα μελέτη, από τον αστροφυσικό και ερευνητή στο Κέντρο Διαστημικής Επιστήμης στο NYU Abu Dhabi, Dimitra Atri, βρίσκει ότι συνθήκες κάτω από την επιφάνεια, θα μπορούσαν, ενδεχομένως, να υποστηρίξουν ζωή – ΠΗΓΗ: Dimitra Atri «Investigating the biological potential of galactic cosmic ray–induced radiation–driven chemical disequilibrium in the Martian subsurface environment», στο Scientific Reports, vol. 10, αrticle
number: 11646 (2020), 28 July 2020. ΑΡΧΕΙΟΝ ΠΟΛΙΤΙΣΜΟΥ, 29.7.2020.
on ancient Mars, raising the question of the possibility of life in such an
environment. Subsequently, with the erosion of the Martian atmosphere resulting
in drastic changes in its climate, surface water disappeared, shrinking
habitable spaces on the planet, with only a limited amount of water remaining
near the surface in form of brines and water–ice deposits. Life, if it ever
existed, would have had to adapt to harsh modern conditions, which includes low
temperatures and surface pressure, and high radiation dose. Presently, there is
no evidence of any biological activity on the planet’s surface, however, the
subsurface environment, which is yet to be explored, is less harsh, has traces
of water in form of water–ice and brines, and undergoes radiation-driven redox
chemistry. I hypothesize that Galactic Cosmic Ray (GCR)-induced
radiation-driven chemical disequilibrium can be used for metabolic energy by
extant life, and host organisms using mechanisms seen in similar chemical and
radiation environments on Earth. I propose a GCR-induced radiolytic zone, and
discuss the prospects of finding such life with Rosalind Franklin rover of the
ExoMars mission.
Viking 2 (1976–1980), was tasked with detecting possible biosignatures on the
Martian surface. Although the mission generated excitement initially, it failed
to detect any biological activity from samples collected from the surface.
Although, recently upon reexamination of results from the Label Release
experiment it has been argued that the possibility of extant life cannot be
ruled out based on Viking results1. With our current understanding of the
planet, a high level of radiation dose prohibits the survival of any stable
ecosystem on the planet’s surface. Based on studies of geological features over
the years, it is generally believed that Mars had abundant liquid water, and
habitable conditions could have existed during the early to middle Noachian
(4.1 to 3.7 billion years ago). Dramatic climate change resulted in drying of
water bodies, and eventually shrinking of habitable spaces available on the
planet. On present day Mars, there is evidence of only trace amounts of water
in the form of brines, polar caps, hydrated minerals, and large deposits of
water ice in the shallow subsurface environment2. The chemical environment also
seems hostile to life. Oxidant species and perchlorates have been detected on
the surface, and if heat activated, have the capability to destroy potential
biomolecules and chemical biosignatures.
probed, measurements from surface rovers, and satellite observations have
provided reliable data to characterize it. Satellite observations of exposed
water ice provides evidence of the existence of water below the surface. Ice
deposits occur at a depth as shallow as 1 m below the surface, extending down
to several kilometers in depth. The Martian surface is bombarded by Galactic
Cosmic Rays (GCRs), which are energetic charged particles and are able to penetrate
a few meters below the surface3. Theoretical modeling of radiation propagation
informs us about the energy deposition rate below the surface. As
discussed later, this continuous supply of energy leads to the formation of a
number of chemical species, some of which may be potentially useful for
metabolic chemistry. This is an additional source of energy along with
radionuclides present in the Martian regolith.
Based on the results of radiation chemistry experiments, and
observations of interstellar ices and comets, it is highly likely that
prebiotic molecules are present below the surface. The degradation of potential
subsurface organic molecules, resulting from GCR penetration occurs on
timescales of millions of years. This degradation effect is therefore
negligible if an active ecosystem currently exists on Mars, since microbes have
much smaller cell turnover times. Although, we do not understand how chemistry
transforms itself into biology, we do understand basic properties of life, and
minimum physicochemical environmental conditions required for life as we know
it. The main aim of the manuscript is to estimate the likelihood of
extremophile survivability in the Martian subsurface environment, which is
planned to be explored with Rosalind Franklin rover of the ExoMars mission6.
One of the objectives of the ExoMars mission is to search for biomarkers; find
evidence of present or extinct life on the planet6. In this manuscript, I
investigate the plausibility of radiation-induced chemical disequilibrium as a
source of metabolic energy for potential Martian biota. In the following
section, I will investigate how the Martian subsurface environment can be
suitable for life, and whether it can be detected with Rosalind Franklin
(ExoMars) rover.…