Biochemical activities leave "fingerprints" in the Earth's atmosphere. As a result of isotope-dependent effects in photosynthesis, respiration, and other biochemical activities, a fingerprint is assigned to the dominant oxygen isotope (16O) compared to higher oxygen-18 (18O) is the concentration. In previous studies, in atmospheric layers below 60 km 18O abundance has been determined, but values above remain uncertain. Now, Helmut Wiesemeyer of the Max Planck Institute for Radio Astronomy in Germany and his colleagues have succeeded. For example, to investigate how changes in the composition of the lower atmospheric layers affect the upper layers on a global scale. 18Using it can shed light on important issues in atmospheric physics.
Often the isotopic composition is determined by measuring air samples collected by suborbital rockets or weather balloons. These instruments allow scientists to explore atmospheric layers up to 60 kilometers high. To increase this altitude (to about 200 km in this case), the scientists used a sensitive spectroscopy technique that detects the presence of isotopes in the atmosphere through the transmission of light from space.
Wiesemeyer and colleagues investigated infrared light emitted from the Moon using detectors at the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA), which ceased operations in September 2022. Because the light is absorbed by the oxygen isotopes, the scientists saw two different narrow "bottoms" in the spectrum. At altitudes between 50 and 200 km, scientists 16Her 18They calculated the forms of the isotope-bound bottoms to determine its ratio to O.
According to Wiesemeyer, new definitions of the boundary between the atmosphere of a life-supporting planet and outer space may result from isotope ratio studies of the upper atmosphere. This threshold is accepted by aviation experts where air entrainment stops. However, he suggests that altitude where a planet's biological activity ceases to dominate its isotopic compositions may be a more viable option for astrobiologists.
Source: physics.aps.org/articles/v16/s19
Günceleme: 02/02/2023 23:45
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