SETI Institute Weekly Colloquium - Upcoming Speakers
Abstract: The discovery of the Higgs boson at the CERN Large Hadron Collider poses new challenges to our understanding of basic quantum physics. Unless other new physics intervenes, we appear to live in a universe that is slightly unstable and will eventually decay catastrophically. Supersymmetry can stabilize the vacuum, but so far searches for superpartner particles at the LHC have come up empty. New ideas jettison supersymmetry, and instead connect the Higgs boson to dark matter.
Abstract: A primary goal of the Kepler mission is to determine the frequency of Earth-sized planets in the habitable zones of other stars. M dwarfs, stars that are smaller and cooler than the Sun, comprise more than 70% of the stars in our galaxy. Finding that Earth-sized planets around M dwarfs are common, therefore, has big implications for determining the frequency of other Earths.
In April 2014 we announced the discovery of Kepler-186f, the first definitive Earth-sized planet found to orbit in the habitable zone of a star other than our Sun. We will discuss our methods of combining ground-based observations with transit modeling to confirm this system, and will present our theoretical studies on the formation and habitability of this planet. We will also present updates on several promising multi-planet systems that have Earth-sized, and possibly sub-Earth-sized, candidates in the habitable zones of cool low-mass stars in the Kepler field-of-view.
At the Mars Phoenix landing site and in much of the martian northern plains, there is ice-cemented ground beneath a layer of dry permafrost. Unlike most permafrost on Earth, though, this ice is not liquid at anytime of year. However, in past epochs at higher obliquity the surface conditions during summer may have resulted in warmer conditions and possible melting. This situation indicates that the ice-cemented ground in the north polar plains is likely to be the most recently habitable place on Mars as near-surface ice likely provided adequate water activity ~5 Myr ago. The possibility of life on Mars is important both for Mars science (Science Mission Directorate (SMD) and Mars Exploration Program Analysis Group (MEPAG) goals and objectives) as well as preparation for human exploration (Human Exploration and Operations Mission Directorate (HEOMD) and Strategic Knowledge Gaps (SKGs) pertaining to biohazards and planetary protection).
The high elevation Dry Valleys of Antarctica provide the best analog on Earth of martian ground ice. These locations are the only places on Earth where ice-cemented ground is found beneath dry permafrost. The Dry Valleys are a hyper-arid polar desert environment and in locations above 1500 m elevation, such as University Valley, air temperatures do not exceed 0°C. Thus, similarly to Mars, liquid water is largely absent here and instead the hydrologic cycle is dominated by frozen ice and vapor phase processes such as sublimation. These conditions make the high elevation Dry Valleys a key Mars analog location where periglacial processes and geomorphic features can be studied in situ.
This talk will focus on studies of University Valley as a Mars analog for periglacial morphology and ice stability. We will discuss observations revealing a unique trend as the depth to ice-cemented ground varies linearly from near zero at the head of the valley to over 80 cm deep 1.5 km away at the valley mouth. This setting provides a natural gradient in physical permafrost properties, water vapor transport, and ice stability. We will also discuss geomorphic ramifications of this ground ice distribution as polygon size is shown to increase down the length of the valley and is correlated with increasing ice depth. Since polygons are long-lived landforms and observed characteristics indicate no major fluctuations in the ice-table depth during their development, the University Valley polygons have likely developed for at least 104 years to achieve their present mature-stage morphology, and the ice-table depth has been stable for a similar length of time. In addition, we will discuss geomorphic features (e.g., rock weathering and erosion, thermal contraction, sublimation till) as possible diagnostics for subsurface ice type. Finally, we will review a landing site selection study encompassing this information gleaned from the Antarctic terrestrial analog studies plus Mars spacecraft data analysis to identify candidate landing sites for a future mission to search for life on Mars.
Abstract: Philosophers have long considered the possibility that we live in an artificial or simulated reality. Dr. Beane will give a short overview of some of the simulation arguments/scenarios that he personally finds most compelling.
Dr. Beane will then attempt to frame the simulation argument in the context of science. In particular, he will discuss recent work which suggests various observational tests of the hypothesis that we are currently living in a simulated universe. These include studies of the cosmic microwave background, high-energy cosmic rays, and high-precision terrestrial experiments.
How did the universe begin ? This is one of the deepest mysteries in science. I will describe the BICEP program, a series of South Pole-based experiments aiming to answer this question by studying the polarization of cosmic microwave background radiation. This whole enterprise is an amazing combination of big ideas (inflation, general relativity, and quantum gravity) and cutting edge technology (superconductors, quantum electronics, microwave engineering, and advanced materials). In March 2014, the second experiment of the series BICEP2 has announced a detection of degree-scale B-mode polarization that is consistent with having an inflationary origin. I will describe what this measurement means and how we are going to follow up on it.
Abstract: Recurring Slope Lineae (RSL) are narrow (0.5 to 5 m) dark albedo features that incrementally lengthen down steep slopes and reoccur each year. RSL are well correlated with temperature, as they lengthen as temperature increases and fade as temperature decreases. RSL have been observed within a latitude band from 37°N to 52°S, but tend to cluster in the southern mid-latitudes (SML) in and around Valles Marineris and Chryse Planitia.
In this talk, Dr. Stillman will demonstrate how observations from the ~25 cm/pixel High Resolution Imaging Science Experiment (Hi-Rise) onboard Mars Reconnaissance Orbiter and surface temperature data acquired by three orbital instruments suggest that RSL are caused by subsurface liquid water flows.
The West Antarctic Ice Sheet contains the ice equivalent of 5 meters of sea level and is slowly adding to the rise of global ocean levels. It is now thought that the ice sheet is undergoing irreversible marine ice sheet collapse. The primary cause is bottom melting of coastal ice shelves in the Amundsen Sea sector driven by oceanic and/or atmospheric factors. In addition, the air temperature over the ice sheet interior has risen substantially over the past 50 years at a rate comparable to that recorded on the adjacent Antarctic Peninsula. There are many tropical and high latitude influences at play governing the atmospheric and oceanic behavior in this part of the world. The talk will lay out what is happening to West Antarctica at present and what may happen in the future as worldwide temperatures continue to increase.
It has been proposed that in Gale Crater, where the Curiosity rover landed in August 2012, lakes developed to various depths after the large central mound (informally referred to as Mt. Sharp) had evolved to a form close to its current topography. Using a combination of CTX and HiRISE imagery and CTX, HiRISE and HRSC topography, we have documented a sequence of rising and falling lake levels, thereby providing a possible relative timeline of the hydrologic events within Gale crater. Assuming that the entrance canyon deposits (the canyon which the Curiosity rover will ascend once it reaches Mt. Sharp) records a back-stepping sequence of fans and deltas, then a corresponding hydrologic sequence is suggested. After the formation of a gilbert-type delta exiting an 84-km long incised valley (Farah Vallis) that drains 270,000 km2 to the south of Gale, and a corresponding lake with an average depth of 700 meters, the inflow of water from Farah Vallis fell or ceased. The lake level dropped considerably, to an elevation at least below the entrance canyon deposits. At a later time, local precipitation drove gully erosion of the Gale rim, and amplified by renewed Farah Vallis runoff, caused a rising lake level that produced deltas on the western rim of Gale and the entrance canyon deposits on Mt. Sharp. This hydrologic system shut down sufficiently abruptly that the deltas did not cut down as the lake evaporated. The time gap between these two lake forming events, perhaps driven by different hydrologic systems, is not yet established. Fan deposition around Gale crater, including the Peace Vallis fan near the rover’s landing site, likely occurred after these large lakes disappeared. This has implications for understanding regional paleo-climates on Mars after the Noachian, as well as providing context for the geology and sedimentology along the Curiosity rover traverse.
Abstract: Since its launch in 2009, NASA's Kepler Mission has transformed our knowledge of exoplanetary system demographics. Kepler's primary mission goal-- to quantify the occurrence rate of habitable zone Earth-size planets around Sun-like stars-- has a clear connection to astrobiology. However, in addition to its planet-finding capabilities, the Kepler data may also be used to study other questions of astrobiological interest. In this talk, I will discuss my work on two such ongoing projects: the quantification of the stellar flare rate, which influences planetary habitability through its influence on atmospheric photochemistry and escape; and the detection of anomalous stellar variability as a form of signal-agnostic optical SETI. Both of these lines of research employ machine learning techniques, making them applicable to the current and future large datasets that now dominate the astronomical landscape.
Abstract: Hydrothermal fields on the prebiotic Earth are candidate environments for biogenesis. We propose a model in which molecular systems driven by cycles of hydration and dehydration in such sites undergo chemical evolution and selection in a dehydrated surface phase followed by encapsulation and combinatorial selection in a hydrated phase. This model is partly supported by recent science, and lies partly in the realm of speculation including a hypothesized pathway for the parallel evolution of the functional machinery of life. Complex models like this present challenges for science in the 21st century and we will describe a new technology to enable the simulation of such models.