by Greg Mayer
Matthew recently asked if there is life on Gliese 581g— a newly discovered Earth-like (in some ways) planet (I’m tempted to say “class M planet“). There’s also the question of if there is life in the Solar System (Earth doesn’t count)– on Europa, or Mars, or Enceladus, say. On the same trip that I got to see the Hall of Human Origins at the USNM, I also visited the Smithsonian’s Air and Space Museum, and got to see the candidate planets and moons up close and personal. There I saw the exhibit “Beyond: Visions of Our Solar System“, a series of exquisite photographs compiled by Michael Benson.
Compiled from the photographic results of what is now several decades of interplanetary probes and Earth satellites, the exhibit includes images of all the planets, the Sun, many moons, and a number of asteroids (a catalogue, with images, is available on Benson’s website, as is a wonderful set of wide angle views of the exhibit hall). The exhibit is, in a word, magnificent. The large format prints, placed on the walls without intervening cases, allows the visitor to examine every detail of the photos.
The detail and high resolution turn the planets from objects of astronomy– moving points of light– to objects of geology, and even hydrology– out wash plains and hills, volcanoes and glaciers. They’re not quite objects of biology yet. We, or our machines, will have to investigate on the surface more closely to see if that’s the case. Here are a few more of the over 100 images.
I can recommend this exhibit without reservation. It will be at Air & Space till next May. A companion volume of exquisite photos, Beyond: Visions of the Interplanetary Probes (Abrams, New York, 2003) is available. (The exhibit contains newer photos, as well as ones from the book, some as recent as 2009.)
Google Mars exists. Google Gliese 581g soon?
Currently I’m betting my money on Titan, it tests okay on the 3 predictions compatible with a reducing metabolism: imbalance of methane at the surface, imbalance of acetylene at the surface, and a carbon isotope ratio deviating from the solar system norm. (It has also a scarcity of surface ethane, but I gather it is thought to be found in the methane seas.) The atmospheric imbalances are claimed to be _really_ difficult to explain without some methane scavenger at the surface. And what would be a good catalyst at those temperatures if not an adapted biological one, I wonder? (Say, by way of free radicals.)
Enceladus may be the nest best bet. Likely an old liquid water reservoir, seemingly with access to organics and minerals, and perhaps not too bad pH.
Mars isn’t looking too god IMO. Methane release is located in volcanic areas (two areas) or buried ice areas (one area), so are best and easiest predicted by ongoing and earlier volcanism. Also, today’s methanogenes have a late metabolism by way of an aerobic methanophile one according to some phylogenetic work, so I dunno how feasible ancestral methanogenic metabolism is. Which leaves methane from decomposing organics as alternative to the more likely volcanism.
Europa places last in the series for me, as it may have a really acidic and later oxygenated sea (surface production!) with not much of either organics or nutrients.
How does metabolism affect the ratio of carbon isotopes? That’s purely a nuclear process.
Why not?
Oh yeah… the Tea Party… nevermind 🙁