February 09, 2015
If you’re a Sigma Xi member who paid annual dues or you’re a life member, you already have access to the Society’s new online community, The Lab: Members to Members. It is a space for discussions with other members about science and engineering. You can login to community.sigmaxi.org by using the email address associated with your membership and creating a password. We invite you to join the conversations!
Below are a few posts from a recent discussion about exoplanets.
From: A Sigma Xi Member
Subject: Exoplanets
Recently the existence of a number of exoplanets has been discovered. Some of those are in the life habitable region of their stars ... I suppose the SETI [Search for Extraterrestrial Intelligence] project is trying to listen for intelligent signals from these planets? The SETI projects looks for signals in the radio and microwave regions of the electromagnetic spectrum. If there are intelligent exos, will they communicate with signals that radiate into space? ... How can we communicate with beings several hundred light-years from us?
From: A Sigma Xi Member
Subject: RE: Exoplanets
Good questions. It is unlikely that our electromagnetic leakage will be detected by alien civilizations. It would require a huge antenna pointed in our direction. On the other hand, for a few billion $$ we could construct a solar powered laser array that would be able to send messages to the nearest stars (Gliese catalog). We have never tried communication, just listening. If all races in the galaxy take that approach we will remain incommunicado.
From: A Sigma Xi Member
Subject: RE: Exoplanets
Someone recently hypothesized that Mars evolved into a habitable planet before Earth, evolved life, and seeded Earth through meteorites blasted off the Martian surface. The recent discovery of Martian meteoritic material with organic materials, almost certainly not terrestrial contamination, supports that speculation as does the recent Curiosity rover detection of spikes of atmospheric methane in Gale Crater, possibly generated by methanogens.
From: A Sigma Xi Member
Subject: RE: Exoplanets
Simulation experiments on the biochemical evolution of life suggests that carbon compounds were among the first to show up, but the processes that winnowed them down to 20 alpha amino acids and single stereo-isomers took a long time. Relevant selective forces are difficult to imagine. These experiments also show that proto-biochemical evolution probably ran backwards, i.e. proteins pre-dated RNA which ran the show before DNA. Recent manipulations of prokaryotic nucleic acids suggest that additional, synthetic nucleotides may code for different aa’s but I don’t know much about them. That may mean that extra-earthly life forms that are nucleic-acid-based may have very different RNAs if not DNAs. Point: carbon compounds in Martian meteorites are to be expected and do not necessarily predict Martian organisms, though they probably contributed to whatever life may have evolved there. Water is important here, but elsewhere? Any methane-based life would be very different from what we’ve got. Will we be able to recognize it? Autocatalysis is key, and simulation experiments suggest that proteins-only can do it—slowly and with relatively low probabilities. Absent competition, that might be enough.
This article was originally published in the March-April issue of Sigma Xi Today.
American Scientist's January-February issue featured NASA's New Horizons' trip past Pluto.