[math-fun] Life on Mars? Latest grist
WDS>1. The Curiosity rover detected time-varying methane concentration in Mars atmosphere, changing by factor>10 over a several-month period. They claim the usual "background" level is about 0.7+-0.25 parts per billion, but it has gone as high as 7.2+-2.1 ppb at least locally near Curiosity (these are 95% confidence intervals). Earth based telescope observations have been claimed to see Mars-wide changes in methane, spiking as high as 60 ppb. To put this in perspective, the total amount of methane (at background level) in the whole Mars atmosphere, is about 200 metric tons. Meanwhile the total amount in the Earth's atmosphere at any time is about 500,000,000 metric tons. 2. Also, it found chlorobenzene in a mudstone rock sample (something like dried clay). Chlorobenzene is the most abundant organic found in that sample (as well as the most complex; several chloro-alkanes were also found) with concentrations between 150 and 300 parts per billion. Chlorobenzene does not occur naturally on Earth but is present in pollution. <WDS Presumably there are microorganisms in the harshest terrestrial deserts. Could Curiosity detect these? I'm guessing the methane is primordial. It's looking really glum for life on Mars. --rwg
Life on Mars?: I have a book (~ "Bacterial Metabolism") originally published in the 1930s, that details an amazing range of (Earth) bacterial energy sources. Bacteria can get by with a gamut of electron donors and acceptors: nitrate, ammonia, sulfides, sulfates, sulfites, hydrogen, ferrous -> ferric and back, and some other metal ions. There was even one disproportionation reaction, where the energy was derived from changing two atoms in an intermediate oxidation state into one higher and one lower. This was mainly soil bacteria; the book predates the discovery of black smokers on the ocean bottom. The human immune system apparently generates Br2 molecules to attack invaders, so its possible that bacteria exist that do similar amazing stunts. For Martian rocket fuel, maybe CO + O2? At least the ingredient CO2 is readily available. Re Matching: I think medical student internships are handled with a matching program where students and hospitals indicate preferences, and a computer does the assignments. This has been around for years, so there might be a body of experience to draw upon. Rich -------- Quoting Hilarie Orman <ho@alum.mit.edu>:
Date: Fri, 19 Dec 2014 10:14:31 -0800 From: Bill Gosper <billgosper@gmail.com> Subject: [math-fun] Life on Mars? Latest grist ...
It's looking really glum for life on Mars.
--rwg
Earth, too.
Hilarie
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