Free Astronomy Magazine November-December 2020

7 NOVEMBER-DECEMBER 2020 ASTROCHEMISTRY neer missions to land probes during the 1970’s and early 1980’s, the conditions on Venus can be brutal, with a mean sur- face temperature of 460 °C. As one moves higher in altitude, the temperature and pressure decrease to where some at- mospheric zones might feel quite pleasant. That said, only the heartiest microbe or prop- erly suited human would find the zone safe even for short periods. The Venusian atmos- phere is reactive to many small molecules of biological interest − including phosphine. The 96.5% carbon dioxide content drives the “runaway green- house effect” that causes the extreme surface temperatures. Sulfuric acid clouds obscure the Venusian surface, mak- ing radar the source of our mapping from orbit of the near-entirely of the planet. Beyond the 3.5% additional nitrogen con- tribution, all other gases are measured in parts-per-million (ppm) or billion (ppb). The 20 ppb-level phosphine detection was accomplished with the James Clerk Max- well Telescope, located high above water vapor at the Mauna Kea Observatory in Hawaii, and was confirmed using the Ata- cama Large Millimeter/submillimeter Array (ALMA), itself located high in the arid Ata- cama Desert in northern Chile. During the press briefing, you could sense the scientists trying to reign in the rampant speculation of viewers to focus on how the detection of phosphine is of consequence because we do not have an explanation for how such concentrations could exist in the Venusian atmosphere given what we know V enusian land- scapes pho- tographed by the landers of the Venera 13 and 14 missions in March 1982. [Roscosmos]