Readers who know of Centauri Dreams' fascination with 'deep time' will not be surprised that I am working on a side project involving past, not future time. Specifically, a study of the Eocene, that remarkable period beginning some 55 million years ago during which the ancestors of most modern mammals -- including the higher primates, such as apes, monkeys and man - appeared. And if the Eocene, 2/3 of the way back to the age of the dinosaurs, seems like a long reach from interstellar travel, ponder this: the more we learn about how life adapts to changing planetary environments, the better we'll be able to carry out the hunt for life around other stars. On that score, it's interesting to see that a team supported in part by NASA's Exobiology program has determined that Earth's continents were in place soon after the planet formed. The Earth was not, in other words, a purely ocean world in that era, or a barren, inhospitable place like the Moon. Analyzing the occurrence of a rare...

"We may never find other life away from Earth, but we have already made aliens on this planet and we will continue to do so at an increasing pace," says Peter Ward, author of Life As We Do Not Know It: The NASA Search for (and Synthesis of) Alien Life (Viking, 2005). "In the last five years we've come to realize that we can make microbial life in a lot more ways than Mother Earth did." Aliens on this planet? Ward is talking about laboratory work here on Earth that has modified life as we commonly understand it. That includes creating microbes with at least one amino acid beyond the 20 found in the DNA of native Earth life. Genetic modification also constitutes, in Ward's view, the creation of an alien lifeform, as does modifying a lifeform to reduce its complexity. Ward, a paleontologist who studies these matters within the University of Washington's astrobiology program, is perhaps best known to Centauri Dreams readers as the co-author (with Donald Brownlee) of Rare Earth: Why...

Yesterday we looked at Milan ?irkovi?'s paper “The Temporal Aspect of the Drake Equation and SETI" (Astrobiology Vol. 4 No. 2, pp. 225-231), and pondered whether there might not be a 'communications window' -- an interval for any society between when it reaches the technological capacity for interstellar communication and the point when it becomes a 'supercivilization' unlikely to use conventional SETI methods to contact us or anyone else. If so, that 'window' would have a profound effect on how many civilizations we might be able to contact via SETI, and would thus change our answers to the Drake Equation. But there are other kinds of assumptions built into the equation that may be problematic. ?irkovi? notes that the equation assumes a more or less uniform physical and chemical history of our galaxy, but uniformitarianism doesn't work well in astrophysics or cosmology (think of the Steady State theory -- uniformitarian -- vs. the Big Bang, which introduced the concept of epochs...

The famous Drake Equation was developed as a way to estimate how many technological civilizations might exist and thereby be targets for SETI research. Conceived in 1961 as astronomer Frank Drake worked at the National Radio Astronomy Observatory (Green Bank, WV), the equation exists in a variety of forms depending on which authors you consult (see, for example, this SETI Institute discussion of the equation). But all variants draw on the same idea: to study extraterrestrial civilizations, you must consider such factors as: the mean rate of star formation in the Galaxy; the fraction of stars that can support life; the fraction of stars that have planetary systems; the number of planets per system with conditions suitable for life; the number of planets where life does originate and evolve; the fraction of planets where intelligent life forms develop; the fraction of planets where intelligent life develops technology; and a final, crucial measure: the mean lifetime of a technological...

To make life happen you need organic molecules that contain nitrogen. Now new work at NASA's Ames Research Center, to be reported in the October 10 issue of the Astrophysical Journal, reveals that organic molecules found throughout the galaxy do, in fact, contain nitrogen. "Our work shows a class of compounds that is critical to biochemistry is prevalent throughout the universe," said Douglas Hudgins, an astronomer at NASA Ames and principal author of the study. The studies combined laboratory experiments and computer simulations. We already knew, thanks to the Spitzer Space Telescope, that complex organic molecules called polycyclic aromatic hydrocarbons (PAHs) are all but ubiquitous. Learning that PAHs contain nitrogen implies that the building blocks of life are seeded everywhere in the universe. From a NASA Ames news release, quoting astrochemist and team member Louis Allamandola: "Chlorophyll, the substance that enables photosynthesis in plants, is a good example of this class...

If you're looking for a terrestrial analogue to one part of the Martian environment, you could do worse than the ice vents inside a frozen volcano on the Norwegian island of Svalbard. There, in a one million year old volcano called Sverrefjell, a team of researchers has found a community of microbes both living and fossilized. Ice-filled volcanic vents are believed to occur on Mars and may well be a potential habitat for life on the planet. Behind the Svalbard investigations is AMASE, the Arctic Mars Analog Svalbard Expedition, which is designing devices and techniques that may one day be used by automated landers to search for life on Mars. And thus far the findings are promising. The team has been able to perform its tests while maintaining scrupulous sterility, a key factor in ensuring that 'life' detections on another planet aren't simply the result of Earthly microorganisms being introduced into the local ecology. Examining 780-million year old sedinmentary rocks, the team also...

The search for extraterrestrial intelligence (SETI) has seen a great deal of publicity, from television programs interviewing involved scientists to blockbuster movies like Contact. But the idea that there might be signs of extraterrestrial life closer to home has received relatively short shrift. Nonetheless, SETA (the search for extraterrestrial artifacts) has spawned interesting work, from Gregory Matloff's examinations of anomalous Kuiper Belt objects to Robert Freitas' surveys of 'halo orbits' around the Lagrangian points. So far both kinds of search -- SETI and SETA -- have come up short, but a few curious things have been observed on each side. One interesting SETA investigation involved an object called 1991 VG, which made a close approach to Earth in 1991 (thanks to Adam Crowl for bringing this one to my attention). Discovered by Jim Scotti using the University of Arizona's Spacewatch telescope (normally used to detect small asteroids near the Earth), 1991 VG seemed to be...

Space artist Jon Lomberg, whose work illustrated yesterday's entry on the white dwarf star GD 362, wrote recently with a comment on Centauri Dreams' September 8 story on Titan. The story discussed new theories on Titan as an abode for life, citing a presentation at the recent Division of Planetary Sciences meeting in Cambridge and quoting Southwest Research Institute scientist David Grinspoon on the possibilities inherent in Titan's abundant hydrocarbons and acetylene, which might help power a metabolism. Titan, of course, is a very cold place, which would seem to inhibit the needed chemistry. But Lomberg points out a way around the problem: "Consider the organic superconductor dimethyltetra-thiofulvalene tetracyano-quinodimethane. Discovered in the 1970s, this was the first organic superconductor found, and it remains superconductive at [relatively] high temperatures. More have been discovered since. When Carl Sagan and I were working on my Encyclopedia Galactica series of...

It's hard to imagine water lasting for long on today's Martian surface. But a team at NASA's Ames Research Center has been studying gully sites that seem to indicate water outflows from what could be a subsurface aquifer. Indeed, the team's computer simulations show that if liquid water did emerge from underground, it could create gullies about 500 meters long. "Our model indicates that these fluvially-carved gullies were formed in the low temperature and low pressure conditions of present-day Mars by the action of relatively pure liquid water," said Jennifer Heldmann, principal author of the Ames study. Take a look at the photograph, which shows the channel and debris apron of recent Martian gullies. The scale of the bar in the photo is 1 kilometer. If we are looking at the work of recent surface water, then it surely existed in a challenging environment. Given the temperature and air pressure at the surface, exposed Martian water should either boil or freeze almost immediately. But...