Free Astronomy Magazine January-February 2021

31 JANUARY-FEBRUARY 2021 ASTRO PUBLISHING Since then, several teams of re- searchers have had the opportunity to analyze those rock samples. Recently, one of the teams, com- posed of Kring, Martin Whitehouse (Swedish Museum of Natural His- tory) and Martin Schmieder (Neu- Ulm University, Germany), has taken the decisive potential step towards confirming the impact- origin hypothesis. The three re- searchers discovered in the rock samples tiny spherules of pyrite (FeS 2 ), just 10 microns in diameter, produced by a microbial ecosystem that proliferated in the streams of water laden with chemical com- pounds that crossed the rocky ravines. The presence of these mi- croscopic sulfur formations, called framboids (due to their vague re- semblance to raspberries, fram- boises in French), can be associated with the activity of organisms that transform sulfate ions (SO 4 2- ) into sulfide (S 2- ), drawing from the process the energy necessary for their survival. It seems that the porous structure of the Chicxulub crater may have offered a habitat, if not actually given rise, to colonies of ther- mophilic organisms capable of transforming to their advantage sulfur compounds transported by water within a hydrothermal sys- tem. From the stratification of sed- iments containing the signatures of those chemical processes, the re- searchers were able to estimate that the organisms’ activity per- sisted for at least 2.5 million years after the impact. This important discovery, pub- lished in Astrobiology at the end of October, suggests that the aster- oidal impacts that occurred be- tween the late Hadean and the upper Archean may have created the ideal environmental conditions for the birth and initial evolution of life on our planet. S ection of the Chicxu- lub core with the hydrothermal minerals dachiardite (bright or- ange) and analcime (colorless and transpar- ent). The minerals par- tially fill cavities in the rock that were niches for microbial ecosys- tems. [David A. Kring, USRA’s Lunar and Planetary Institute] !