Now this sounds interesting… NASA will hold a news conference on December 2 at 11:00 am PT (2:00 pm ET) to discuss an “astrobiology discovery” that will “impact the search for evidence of extraterrestrial life.” Details are embargoed until the time of the conference, so what this entails exactly isn’t known yet. It will be held at NASA headquarters in Washington, broadcast live on NASA Television and streamed on the NASA website. Let the speculation begin…
Addendum (November 30):
From the discussions going on, it appears that the news conference probably has something to do with shadow biospheres, the search for truly alien forms of primitive life that co-exist with us here on Earth but based on biochemistry different from all other known life forms, specifically arsenic instead of phosphorous, for example. Such confirmation would make the search for extraterrestrial “life as we don’t know it” much more plausible and perhaps easier to find. From this update:
“Astrobiologists are aware that extraterrestrial life might differ from known life, and considerable thought has been given to possible signatures associated with weird forms of life on other planets. So far, however, very little attention has been paid to the possibility that our own planet might also host communities of weird life. If life arises readily in Earth-like conditions, as many astrobiologists contend, then it may well have formed many times on Earth itself, which raises the question whether one or more shadow biospheres have existed in the past or still exist today. In this paper, we discuss possible signatures of weird life and outline some simple strategies for seeking evidence of a shadow biosphere.”
“All known life requires phosphorus (P) in the form of inorganic phosphate (PO43- or Pi) and phosphate-containing organic molecules. Piserves as the backbone of the nucleic acids that constitute genetic material and as the major repository of chemical energy for metabolism in polyphosphate bonds. Arsenic (As) lies directly below P on the periodic table and so the two elements share many chemical properties, although their chemistries are sufficiently dissimilar that As cannot directly replace P in modern biochemistry. Arsenic is toxic because As and P are similar enough that organisms attempt this substitution. We hypothesize that ancient biochemical systems, analogous to but distinct from those known today, could have utilized arsenate in the equivalent biological role as phosphate. Organisms utilizing such ‘weird life’ biochemical pathways may have supported a ‘shadow biosphere’ at the time of the origin and early evolution of life on Earth or on other planets. Such organisms may even persist on Earth today, undetected, in unusual niches.”
Some of the listed speakers have been involved in this kind of research, including how it may apply to exotic environments such as on Titan (possible methane-based life, as discussed previously) as well as Mars, etc. See also this update today here. Is this what will be announced? We’ll see Thursday, but it would seem to fit with the speakers’ backgrounds as well as the description given, of a discovery that will impact the search for extraterrestrial life. There has been a lot of speculation today that some kind of such life has already been found in one of these places, but that would appear to be very premature, given a look at the actual available information, in context.