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AbGradCon Ho!

My abstract on “Warming Early Mars with NO2″ has been accepted for a talk at this summer’s Astrobiology Graduate Conference! I’ll discuss a possible mechanism by which early Mars (3 billion years ago) could have sustained above-freezing temperatures as well as liquid water with a carbon dioxide/water vapor/nitrogen dioxide greenhouse effect. We are currently putting the finishing touches on our manuscript before submitting it to Earth & Planetary Science Letters in a week or so.

The organizers of AbGradCon09 have done a great job of putting together an excellent conference, including a field trip to Mt. St. Helens. Additionally, the conference will be broadcast live on Second Life, so if you can’t travel to Seattle you can still participate!

The Milky Way is old enough that a slightly more advanced civilization than us could conceivably have colonized the galaxy several times over by now. Known as the Fermi Paradox, the absence of extraterrestrial observations is often taken to imply either the rarity of life or the impossibility of interstellar travel.

In a paper published in the February issue of the Journal of the British Interplanetary Society titled “The Sustainability Solution to the Fermi Paradox”, we challenge this conclusion with the possibility that exponential growth is an unsustainable development. That is, even if an extraterrestrial civilization has colonized the galaxy, it would have done so through rapid unsustainable growth and collapsed upon reaching a physical resource limit. Not enough time has yet passed for a sustainable growth civilization to colonize the galaxy, so there is still promise in the search for extraterrestrial life. Furthermore, though the absence of extraterrestrial civilization does not imply the unsustainability of exponential growth, it does increase the probability that humanity should transition to sustainable development in order to prevent its collapse. A more detailed writeup is available on the Lifeboat Foundation blog.

In other news, NASA’s Kepler Mission successfully launched yesterday evening! Over the next three years, Kepler will observe 100,000 stars in a patch of the Milky Way in search of Earth sized planets. This is the first mission with the capability of detecting Earth at a distance, so with any luck we’ll soon have a better idea of just how common small rocky planets are in the galaxy.

My MS paper, “A Revised, Hazy Methane Greenhouse for the Archean Earth”, just appeared in the journal Astrobiology! You can view a PDF of the article on my research page.

We argue that the warm, ice-free climate of the early Earth (2.8 billion years ago) was maintained by a water vapor/carbon dioxide/methane/ethane atmospheric greenhouse effect that offset the ~20% reduction in solar luminosity from the faint young sun. Furthermore, a stabilizing feedback between life and the climate system may have resulted in a thin stratospheric organic haze that maintained above-freezing temperatures and shielded ultraviolet radiation. An excellent write-up of our work is available at The Planetologist.

I’ve given this talk several times over the past couple years, most recently on the Forum for Astrobiology Research (which should eventually be available as a podcast), and it feels good to finally see the paper come out.