Since this is a particularly interdisciplinary workshop, we've asked our speakers to recommend papers that will be useful for further exploration.
This is a link to a NASA press release describing a special collection on Exoplanet Biosignatures published in June 2018 in Astrobiology by NASA's Nexus for Exoplanet System Science.
Annual Review from 2006.
On the coevolution of the Earth's interior and surface environment, and the latest summary on the extent of dry landmasses through Earth history.
On the modes of mantle convection through Earth history, i.e., the onset of plate tectonics and its subsequent evolution.
There will be two hands-on sessions during the 2019 Sagan Workshop and they will be introduced on Tuesday afternoon. Participants in the hands on sessions will be split into small groups to complete projects. You will have time to work on these projects Thursday afternoon and they will be presented on Friday afternoon.
Please use this link to sign up for one of the hands-on sessions; note that you can only participate in one. There is also a limit on the number of participants in each session (60 in ExoPlex, 100 in ExoEarth Finder). Starting on Wednesday, you will be able to sign up for specific group projects in your chosen hands-on session.
Read this document to learn what you'll need to be ready for the Hands-On Sessions.
Read these instructions for what you'll need during the Hands-on Sessions including how to log in to the AWS instances and a list of useful commands.
The myriad of exoplanet discoveries and technological advances over the last decades have brought the possibility of finding truly Earth-like planet around other stars within reach. However, the challenges involved in identifying such planets from interstellar distances remain formidable. For one thing, the Earth at a distance of 10 parsecs is about 2 magnitudes fainter than the faintest sources in the Hubble Ultra Deep Field. The spectra will be of very faint, unresolved points of light. Those data can contain a wealth of information, but it is important be aware of the potential pitfalls when interpreting relatively low-quality data in a situation where many basic parameters of the planets are unknown.
To that end, you will be provided with a set of simulated exoplanet reflection spectra containing both statistical noise and instrumental effects, such as might be obtained with a high-contrast coronagraph coupled to a large space telescope. The range of planets will span a subset of the currently known exoplanet types. You will be provided only with the information about each planet that we can expect to know in advance of (or nearly simultaneously with) acquisition of the spectra.
Your job will be to approach the data with an open mind, attempt to classify the planets, and identify potentially habitable ones for follow-up observations. While doing this, you will also investigate the data quality and instrumental requirements needed to properly identify habitable (or inhabited) exoplanets. The data will be provided as text files of wavelength, flux, and error. A Jupyter python notebook will allow you to plot the spectra and link to a database of gaseous molecular absorption features. No complex analysis will be required; this project primarily calls upon your ability to sort, classify, and judge.
This PDF version of the Jupyter notebook will give you some idea of what this hands on session is about. It will be explained in more detail during the presentation by Aki Roberge on Wednesday afternoon.
There will be 10 different groups in this hand-on session; each group will analyze four simulated exoplanet spectra.
These 4 documents describe the ExoPlex group projects in detail.
The interior of a planet plays an important role in a planet's habitability. For example, melting of material allows for the degassing of climate-stabilizing gasses, heat flow from the core aids in the creation of a magnetic field, and bulk composition may change the availability of bio-essential elements by changing the mineralogy of surface rocks. The number of observables available for inferring the composition of an individual exoplanet, however, is extremely limited. Optimistically, we will be able to determine a planet's mass, radius, orbital properties and atmospheric composition.
Mass and radius together provide our best observables for inferring exoplanetary structure and composition due to the trade-off between these variables and their bulk density. Those planets with large radii and low mass must be made of lower density materials (e.g. water) compared to those with having large mass and small radii more indicative of rock and iron. More likely, rocky planets contain all of these materials in some proportion, and so we must turn to mass-radius models to begin to sort out their potential compositions.
In this hands-on session we will use the ExoPlex mass-radius-composition calculator to explore the observational consequences of varying planet composition. We will explore how bulk planet composition affects mantle mineralogy, as well as the effects of surface water on the planetary density. Some potential team topics include: quantifying the effects of the oxidation state of Fe on mass and radius, quantifying the amount of water needed to best-fit the TRAPPIST-1 planets, examining the role of Mg/Si on mantle mineralogy and the consequences on mass and radius.
PyMOL will be used to visualize two of the nanomachines that made substantial contributions to early metabolism on earth. Ferredoxins are iron sulfur cluster containing electron transfer proteins that mediate a wide variety of electron transfer reactions across the tree of life. Hydrogenases are more complex and they utilize a string of iron sulfur clusters to act as a wire to shuttle electrons to and from the catalytic center for splitting hydrogen gas or to reduce water to form hydrogen. We will use PyMOL to explore the protein environment around these clusters and the path electrons take to and from the hydrogenase catalytic center.
If you would like to install the software on your own computer to customize some of the visualizations, you can download and install PyMOL with these instructions. Installation is not required for the PyMOL demonstration during the workshop.
(last updated August 5th, 2019 10:50:50)