This week we have some more comment summaries from the Astrobiology for Astronomers Workshop from Caltech and a look inside a lava tube and strange illusion seeming to show multiple suns. Also it is time to head back to Pasadena for the Ninth International Mars Conference. See all of you Martians there!
So after the Mars Conference the next AAS conference will be in Hawaii on Jan 4-8, 2020. I, as a an affiliate member and have discounted entry fee, do normally attend the AAS meetings and had looked forward to attending the winter meeting. But, with the meeting being held in Hawaii, I wonder if while in Hawaii I would want to be sequestered in a hotel conference center. Hmm, I'm not sure I can get Resident Astronomer Peggy to go along while I sit in a conference room, so as much as we want to get back to Hawaii, is this really the way to do it or not? You can check out the details of the meeting at: https://aas.org/meetings/aas235.
Anyway, we still have time to plan for that, and while we decide we received this photo from OCA Science Nerd and Theatre Impresario, Scott, of this Resident Astronomer inside of a lava tube on Rapa Nui. Lava tubes offer some big advantages to future explorers who arrive on the Moon or on Mars. The lava tubes can provide protection from the solar radiation and extreme sunlight temperature variations. This photo shows me emerging from deeper within the lava tube, just past a skylight in the tube. Thanks for that photo, Scott!
|Resident Astronomer George explores Rapa Nui lava tube with skylight above (Source: OCA Scott Graham)|
Ok, back to the present time, while out on a tour of the observatory grounds with Resident Astronomer Peggy and Astronomer Assistants, Danny and Ruby, we spied a strange combination of lights in the morning sky. Hmm, that looks like the moon or the moon and the sun, or something else? Well, it is actually the sun that shows up as the round disk, but what are the other bright disk looking images? Hmm, can the sun really just break through at various points in the clouds or what? The bright circle of light, to the right of the sun, sure looks like a real object, but, really how does that happen? Anybody out there that can fill us in on what we are really seeing?
|Early morning (7:26AM) sun with several imposters? (Source: Palmia Observatory)|
Ok, enough of that particular mystery and now back to some additional comments to the last sessions of the Astrobiology for Astronomers Workshop. I enjoyed hearing from Professor Ken Nielson, retiring next year from USC, presented a big picture view of life and biosignatures. After spending two days in Pasadena, attending the workshop in person, this slide and following slides are from the streaming online opportunity where I now attend from my cozy arm chair in my office!
|What is life or what does it do? (Source: Ken Nielson, USC, at Astrobiology for Astronomers Workshop)|
Of these key features of life on planets, we need to keep in mind how life is a process that maintains the planets atmosphere in disequilibria. as summarized by Josh Krissansen-Totan, U of Washington. Life is a process that can take the Gibbs free energy from the sun and maintain order and increasing complexity, even in light of the 2nd law of thermodynamics, because if degrades the low entropy light even faster than would other natural processes. The disequilibria creates biosignatures that we can search for and hopefully identify on exoplanets.
|Life is a disequilibrium process (Source: Josh Krissansen-Totton, U of Washington)|
Professor Ken Nielson continues and describes how these biosignatures might be detected.
It is interesting to see some of the impacts of life on the disequilibria introduced by life as it shows up in the proportion of elements as measured in natural settings and comparing that with the proportions found in living organisms. So we see that the chemical properties of carbon, phosphorus and nitrogen and a few other metals are selectively used in biological material.
|Life sequesters elements in distinctive ratios (Source: Ken Nielson, USC, at Astrobiology for Astronomers Workshop)|
Now, while the biologists and chemists and geologists identify possible biosignatures it is still up to the astronomers to actually look at exoplanet and search for observational evidence. To do that, we will need telescopes with even bigger apertures. This slide shows how in order to come close to finding these observable biosignatures will require large diameter telescopes in order to meet the required signal to noise criteria. So if it turns out that you need to double the S/N ratio, then you can achieve this by either doubling the size of the telescope aperture or by increasing the observing time by four times. Other issues like atmospheric seeing degradations will require even more improvements in adaptive optics.
|Imaging or resolving exoplanet atmospheric biosignatures requires large telescopes (Source: Jared Males, U of Arizona)|
During the question and answer period following many of the presentations, the interdisciplinary nature of identifying biosignatures became very apparent. The discussion often proceeded from a biologist asking a question that only a chemist could answer or from an astronomer that a geologist had to answer and other combinations of interdisciplinary nature. After the workshop, I found that I had to return to the 1200 page classic, "The Molecular Biology of the Cell" to help fill in some of the gaps in my understanding of the discussions. If you are interested in biosignatures, reviewing a copy of this class textbook is a good way to get into more of the details. Beware though, the book is heavy into biology and chemistry, which is often tough going for the astrophysicist wannabe!
|Very good textbook for understanding cellular biochemistry (Source: Molecular Biology of the Cell)|
So, I pulled just two figures out of the book that sort of exemplifies how all of Earth based life is the result of electron flow between various arrangements of biological molecules and even before life began the precursors from geochemistry also relied on the flow of electrons between various mineral combinations that enabled extraction of free energy to generate complexity.
Inside the mitochondria, the electron transport chain takes advantage of the free energy available to carry out the processes of life. Instead of combining the hydrogen and oxygen directly, which would release way too much energy, as an explosion, the mitochondria recover the energy in several smaller steps, each step taking just enough energy to accomplish the biological tasks at hand, and finally delivering the electrons to the end product of combining them with oxygen. Biologists follow the electrons, but remember that the protons are always part of the reaction too as everything eventually remains electrically neutral.
|Photosynthesis leads to the Great Oxidation Event (Source: Molecular Biology of the Cell)|
So, these two figures just begin to get into the whole complicated reactions and molecular structures involved in biological processes. All aspects of these reactions leave some imprint and change the atmosphere or oceans or land and it is these biosignatures that scientists are looking for on exoplanets. Remember too that the search for biosignatures must be widened to include other forms of possible energy extraction schemes that could differ from those used here in this one and only example of life in the universe.
Until next time,
Resident Astronomer George
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