SETI Institute Weekly Colloquium
At the Microsoft Campus in Mountain view
1065 La Avenida St, Mountain View CA
FREE and open to the public. Tuesdays, noon to 1pm
(1) saving civilization on Earth from the worst ravages of climate change by scaled-up 2F-MSBRs;
(2) using the fission fragments of related nuclear fission reactions for ion-propulsion that produces rockets two to three orders of magnitude faster than achievable with chemical rockets, making possible, perhaps, a first generation of starships.
Two key technologies are revolutionizing the way humans conduct spaceflight, namely, the miniaturization of satellites (e.g., micro- and nano-satellites) and the distribution of payload tasks among multiple coordinated units (e.g., spacecraft formation-flying, on- orbit servicing/robotics, fractionation, swarms). The combination of these techniques promises breakthroughs in space science (e.g., through imaging of earth-like planets, characterization of gravitational waves), remote sensing (e.g., through synthetic aperture radar interferometry, gravimetry), and exploration (e.g., on-orbit servicing, assembly of large structures).
Irrespective of the specific application, future formation-flying missions require a high level of autonomy to maintain and reconfigure the relative motion of the participating vehicles within the prescribed accuracy and range of operations. Since these requirements cannot be generally met by state-of-the-art spaceborne technology, the goal of current research is to pave the way for the autonomous Guidance, Navigation, & Control (GN&C) of the participating space vehicles.
After an introduction of the author’s contributions to the most recent satellite formation- flying missions in low earth orbit (TanDEM-X and PRISMA), this presentation will address the astrodynamics and GN&C algorithms which are under developments to enable a new class of formation-flying instruments. A novel low-cost mission concept developed by the author is introduced, the so-called miniaturized Distributed Occulter/Telescope (mDOT). mDOT consists of two small formation-flying satellites precisely positioned in high elliptical orbit to directly image exozodiacal dust and exoplanets. Finally, the high-fidelity virtual reality and physical testbed under development at Stanford for the verification of the formation-flying sensors and navigation algorithms will be described.
In 1960 two seminal papers in SETI were published, providing two visions for SETI. Giuseppe Cocconi and Philip Morrison’s proposed detecting deliberate radio signals ("communication SETI"), while Freeman Dyson ("artifact SETI"), proposed detecting the inevitable effects of massive energy supplies and artifacts on their surroundings. While communication SETI has now had several career-long practitioners, artifact SETI has, until recently, not been a vibrant field of study.
The launch of the Kepler and WISE satellites have greatly renewed interest in the field, however, and the recent Breakthrough Listen Initiative has provided new motivation for finding good targets for communication SETI. Dr. Wright will discuss the progress of the Ĝ Search for Extraterrestrial Civilizations with Large Energy Supplies, including its justification and motivation, waste heat search strategy and first results, and the framework for a search for megastructures via transit light curves. The last of these led to the identification of KIC 8462852 (a.k.a. "Tabby's Star") as a candidate ETI host. This star, discovered by Boyajian and the Zooniverse Planet Hunters, exhibits several apparently unique and so-far unexplained photometric properties, and continues to confound natural explanation.
The SETI Institute REU students Class of 2016 will summarise their summer projects in exciting 3 minute lightning talks!
The coldest known exoplanets are still much hotter than the gas giant planets in our own Solar System. Pushing to colder temperatures requires observing in the thermal infrared (3-5 microns) where self-luminous gas-giants peak in brightness.
Dr. Skemer will present observational studies characterizing the atmospheres of the coldest exoplanets and the coldest brown dwarf. These observations include a planet whose metallicity is higher than its host star, and a 250 K brown dwarf which shows signs of water clouds. Additionally, he will describe a new instrument that can obtain spectroscopy of directly imaged planets from 3-5 microns.
Dwarf galaxies tend to form stars inefficiently. Yet, blue compact dwarf (BCD) galaxies are a subset of dwarf galaxies that have intense and concentrated star formation (compared to typical dwarf galaxies). BCDs are thought to require a large disturbance to trigger their burst of star formation. A common theory is that the enhanced star formation in a BCD is the result of an interaction with another galaxy or a dwarf-dwarf galaxy merger. However, many BCDs are relatively isolated from other galaxies, making an interaction or a merger a less likely starburst trigger.
As part of the atomic hydrogen dwarf galaxy survey, LITTLE THINGS*, Dr. Ashley has studied the gaseous properties of six BCDs. Atomic hydrogen data allow us to explore the velocity fields and morphologies of the gas in BCDs, which may contain signatures of star formation triggers, such as gas consumption, a past merger, and interaction with previously undetected companions. If BCDs have formed through gas consumption or dwarf-dwarf mergers, then they would be useful analogs for galaxy formation in the early universe. Also, learning which large disturbance has triggered the burst of star formation in BCDs could be useful for understanding and modeling how/whether BCDs evolve into/from other types of dwarf galaxies.
In the last few years we have found that Mars' south polar cap has as much carbon-dioxide as Mars' current atmosphere. This raises numerous questions about how this massive deposit formed and what Mars was like when it was in the atmosphere. Using a combination of methods including spacecraft imagery, radar, and modeling we can start to answer some of these questions. Carver Bierson will discuss evidence that these deposits may have formed over several cycles of Mars atmosphere collapsing onto the surface and then sublimating back into the atmosphere.