Perseverance pronašao tragove u drevnom koritu rijeke
NASA je objavila da je rover Perseverance prošle godine zabilježio potencijalne biosignale u starom, suvom koritu rijeke na Marsu. Uzorci iz kamena nazvanog Cheyava Falls pokazuju strukturu koja upućuje na moguć mogući biološki porijeklo, ali je potrebno dodatno istraživanje prije konačnih zaključaka.
Rover je naišao na taj kamen u julu 2024. dok je istraživao stjenoviti izdanak Bright Angel formacije na rubu drevne riječne doline. Perseverance je detektovao slojeve gline i mulja, materijale koji su na Zemlji izvrsni u očuvanju prošlih mikroba, što pojačava interes za potencijalne biosignale na Marsu.
"The identification of a potential biosignature on the Red Planet is a groundbreaking discovery, and one that will advance our understanding of Mars," "closest we have ever come to discovering life on Mars."
Na kamenu su uočene šarene, "leopard spots" mrlje koje su sadržavale greigite (gvožđe-sulfid) i vivianite (hidratovani gvožđe-fosfat), minerale koji na Zemlji često nastaju u prisustvu razlažuće organske materije i mikroba. "The combination of chemical compounds we found in the Bright Angel formation could have been a rich source of energy for microbial metabolisms,"
Međutim, istraživači upozoravaju da nije moguće isključiti abiotske reakcije koje bi mogle proizvesti slične mineralne tragove. "But just because we saw all these compelling chemical signatures in the data didn’t mean we had a potential biosignature," "We needed to analyze what that data could mean." "These reactions appear to have taken place shortly after the mud was deposited on the lake bottom," "On Earth, reactions like these, which combine organic matter and chemical compounds in mud to form new minerals like vivianite and greigite, are often driven by the activity of microbes."
Otkriće u Bright Angel formaciji moglo bi da znači da je Mars bio pogodniji za život duže nego što se ranije mislilo, ali naučna zajednica traži čvrste dokaze i recenziju. "Astrobiological claims, particularly those related to the potential discovery of past extraterrestrial life, require extraordinary evidence," "Getting such a significant finding as a potential biosignature on Mars into a peer-reviewed publication is a crucial step in the scientific process because it ensures the rigor, validity, and significance of our results," "And while abiotic explanations for what we see at Bright Angel are less likely given the paper’s findings, we cannot rule them out." "there are chemical processes that can cause similar reactions in the absence of biology," "completely on the basis of rover data alone."
