- Weekly Seminar - Manish Mehta
- Special Seminar - Thomas Schildknecht
- Weekly Seminar - Andrew Ault
- Weekly Seminar - Claire Newman
Weekly Seminar - Manish Mehta
September 15, 2016 - 3:30 pm
Title: "Launch Vehicle Base Flows"
Abstract: Lack of understanding of launch vehicle base flows have led to a series of catastrophic rocket explosions from the 1960s to modern day. Inadequate predictions of base heating and flow physics have led to the failures of many government and private launch vehicles during ascent (e.g. Polaris, Atlas, N-1, Prospector, etc.). Hot rocket plume-induced base flows can lead to thermal breakdown of multiple components within the vehicle base such as the propulsion systems, gimbal actuators, avionics and structural hardware. Thermal protection systems (TPS) are used to protect these components from high heating environments, and their design can be compromised and lead to mission failure due to inadequate predictions. Overly conservative TPS design, which can weigh ~2,000 lbs per inch for a typical launch vehicle, can lead to a significant reduction in payload mass. As a result, accurate base environment estimates and TPS designs are critical for human spaceflight missions.
This seminar will discuss the gas dynamics for multi-rocket engine launch vehicle base flows during lift-off to main-engine cut-off (MECO) and the technical challenges with predictions of such complex flows. The seminar will also present NASA heritage and innovative methods to accurately estimate base heating environments specifically for the deep-space heavy-lift rocket, the Space Launch System, which is currently being built.
Special Seminar - Thomas Schildknecht
September 16, 2016 - 1:30 pm
Title: "Space Debris Research at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald"
Abstract: The proliferation of space debris and the increased probability of collisions and interference raise concerns about the long-term sustainability of space activities, particularly in the low-Earth orbit and geostationary orbit environments. During recent years governments, space agencies and civilian research organizations increased their efforts to build space object catalogues and to investigate the space debris population in different orbit regions. Understanding the nature and the sources of debris is a prerequisite to provide the scientific foundation for a sustainable use of near-Earth space.
This presentation will describe current space debris research activities to detect and characterize space debris at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald. In particular optical techniques to detect track and characterize space objects including small-size debris will be presented and illustrated with examples from the long-standing observation programs of the Astronomical Institute of the University of Bern (AIUB).close
Weekly Seminar - Andrew Ault
September 22, 2016 - 3:30 pm
Title: Catching the Freshwater Wave: Lake Spray Aerosol Production, Size, and Chemical Composition in the Lab and Field
Abstract: Aerosol production from wave breaking on freshwater lakes, such as the Laurentian Great Lakes, is poorly understood in comparison to sea spray aerosol (SSA). Herein, lake spray aerosol (LSA) is defined as aerosol generated from freshwater through bubble bursting, analogous to SSA from seawater. LSA have the potential to impact regional climate and health, but their composition has not been reported. LSA number concentration, size, and chemical composition were measured on the southeastern corner of Lake Michigan during an event with wave heights up to 3.1 m (July 6 – 8th, 2015). Single particle microscopy and mass spectrometry analysis of field and lab-generated samples show that LSA particles are primarily calcium (carbonate), with lower concentrations of other inorganic ions and organic material. These measurements were coupled with results from an LSA generator used to isolate the properties of LSA from background particles. These studies of LSA are needed as models, at present, utilize SSA parametrizations for freshwater systems. As LSA can be generated and act as CCN, IN or eject toxic materials from harmful algal blooms, an improved understanding of LSA physicochemical properties is needed to determine the impacts on climate and health in the Great Lakes region.close
Weekly Seminar - Claire Newman
September 29, 2016 - 3:30 pm
Title: "The Winds of Mars"
Abstract: From Dr. Newman: "I will talk about the history of our discovery of the importance of wind in producing the martian surface we see today, and will also talk about the past, present, and future of Mars wind observations. Combining orbital and surface observations and atmospheric models, I will describe the general large-scale and small-scale pattern of winds and discuss how wind affects everything from dust storms and albedo variations to sand dunes and topography. I will also present results from the Curiosity rover, which recently made the first observations of winds in an active dune field on another planet."