Traffic Infraction, He Wrote

Probably the greatest thing about this country, aside from the fact that virtually any random bonerhead can become president, is the American system of justice

Pain & Suffering

As an American, you are very fortunate to live in a country (America) where you have many legal rights

Spacecraft design project: Low Earth orbit communications satellite

This is the final product of the spacecraft design project completed to fulfill the academic requirements of the Spacecraft Design and Integration 2 course (AE-4871) taught at the U.S. Naval Postgraduate School. The Spacecraft Design and Integration 2 course is intended to provide students detailed design experience in selection and design of both satellite system and subsystem components, and their location and integration into a final spacecraft configuration. The design team pursued a design to support a Low Earth Orbiting (LEO) communications system (GLOBALSTAR) currently under development by the Loral Cellular Systems Corporation. Each of the 14 team members was assigned both primary and secondary duties in program management or system design. Hardware selection, spacecraft component design, analysis, and integration were accomplished within the constraints imposed by the 11 week academic schedule and the available design facilities

A digital video system for observing and recording occultations

Stellar occultations by asteroids and outer solar system bodies can offer ground based observers with modest telescopes and camera equipment the opportunity to probe the shape, size, atmosphere and attendant moons or rings of these distant objects. The essential requirements of the camera and recording equipment are: good quantum efficiency and low noise, minimal dead time between images, good horological faithfulness of the image time stamps, robustness of the recording to unexpected failure, and low cost. We describe the Astronomical Digital Video occultation observing and recording System (ADVS) which attempts to fulfil these requirements and compare the system with other reported camera and recorder systems. Five systems have been built, deployed and tested over the past three years, and we report on three representative occultation observations: one being a 9 +/-1.5 second occultation of the trans-Neptunian object 28978 Ixion (mv=15.2) at 3 seconds per frame, one being a 1.51 +/-0.017 second occultation of Deimos, the 12~km diameter satellite of Mars, at 30 frames per second, and one being a 11.04 +/-0.4 second occultation, recorded at 7.5 frames per second, of the main belt asteroid, 361 Havnia, representing a low magnitude drop (Dmv = 0.4) occultation.Comment: 9 pages, 5 figures, 3 tables, accepted to Publications of the Astronomical Society of Australia (PASA

Model-Based System Engineering and Software System Safety Workshop

The G-48 System Safety Committee sponsored a Model-Based System Engineering (MBSE) and Software System Safety (SSS) workshop, hosted by A-P-T Research, Inc. (APT) in Huntsville, Alabama, on May 2-3, 2017. The idea of this workshop evolved at the 34th International System Safety Conference (ISSC) in Orlando, Florida, during presentations and a paper by Barry Hendrix, which noted that the MBSE needs to include more system safety and software system safety processes. An action recorded under urgent-need topics by International System Safety Society (ISSS) Fellow Dave West at the G-48 meeting in Orlando resulted in volunteers to host and coordinate the workshop. The MBSE SSS workshop consisted of a panel of seven subject matter experts. Approximately 40 attendees were present and more than 70 people viewed the workshop via a NASA live video streaming feed. The MBSE SSS panel consisted of Barry Hendrix, APT; Dr. Fayssal Safie, APT; Dr. Donna Havrisik, Government Agency System Engineering; Josh McNeil, AMRDEC Software Engineering Directorate (SED); David Arterburn, University of Alabama Huntsville; Joe Hale, NASA; and Paul Gill, NASA. Many attendees were from local Redstone Arsenal agencies, such as AMCOM, PEO Missiles & Space, and the Missile Defense Agency. Several contractors from companies within Cummings Research Park also attended. Special out-of-town guests included Peggy Rogers, U.S. Navy Software System Safety Technical Review Panel (SSTRP); Bob McAlister, U.S. Air Force; and Lynece Pfledderer, Lockheed Martin (LM), along with five other LM attendees from Texas, Florida and Connecticut

Verifying timestamps of occultation observation systems

We describe an image timestamp verification system to determine the exposure timing characteristics and continuity of images made by an imaging camera and recorder, with reference to Coordinated Universal Time (UTC). The original use was to verify the timestamps of stellar occultation recording systems, but the system is applicable to lunar flashes, planetary transits, sprite recording, or any area where reliable timestamps are required. The system offers good temporal resolution (down to 2 msec, referred to UTC) and provides exposure duration and interframe dead time information. The system uses inexpensive, off-the- shelf components, requires minimal assembly and requires no high-voltage components or connections. We also describe an application to load FITS (and other format) image files, which can decode the verification image timestamp. Source code, wiring diagrams and built applications are provided to aid the construction and use of the device.Comment: 10 pages, 7 figures, accepted to Publications of the Astronomical Society of Australia (PASA

Measuring lateral heat flux across a thermohaline front: A model and observational test

We develop and test a method to observationally estimate lateral intrusive heat flux across a front. The model combines that of Joyce (1977), in which lateral cross-frontal advection by intrusions creates vertical temperature gradients, and Osborn and Cox (1972) in which vertical mixing of those gradients creates thermal microstructure that is dissipated by molecular conduction of heat. Observations of thermal microstructure dissipation χT are then used to estimate the production by intrusions, and hence the lateral heat flux and diffusivity. This method does not depend on the precise mechanism(s) of mixing, or on the dynamical mechanisms driving the frontal intrusions. It relies on several assumptions: (1) lateral cross-frontal advection produces diapycnal temperature gradients that are mixed locally, (2) thermal variance is dissipated locally and not exported, (3) intrusion scales are larger than turbulence scales, and (4) isotropy of temperature microstructure is assumed in order to estimate χT.The method is tested using microstructure observations in Meddy Sharon, where the erosion rate and associated lateral heat flux are known from successive mesoscale hydrographic observations (Hebert et al., 1990). An expression is developed for the production (lateral heat flux times lateral temperature gradient, expected to equal χT) in a front of steady shape that is eroding (detraining) at a steady rate; the production is proportional to the erosion speed and the square of the cross-frontal temperature contrast, both of which are well-known from observations. The qualitative structure and integrated value of the dissipation agree well with model assumptions and predictions: thermal variance produced by lateral intrusive heat flux is dissipated locally, dissipation in intrusive regions dominates total dissipation, and the total dissipation agrees with the observed erosion rate, all of which suggests that microstructure observations can be used to estimate intrusive heat flux. A direct comparison was made between lateral heat flux estimated from mesoscale Meddy structure plus the known rate of erosion, and lateral flux based on microscale temperature dissipation, with excellent agreement in the frontal zone and poorer agreement where lateral temperature gradient is too small to accurately measure

Fusion of Diverse Performance Inertial Sensors for Improved Attitude Estimation Within a Stabilisation Platform for Electro-optic Systems

Within line of sight pointing and stabilisation of EO (Electro-optic) systems operating under motion disturbances it is desirable to measure the inertial orientation of different parts of the system, not just the line of sight - this would allow additional information to be added to the control loop. To implement this a framework to fuse the multiple inertial sensors of the EO system is considered, with an example implemented. The fusion of higher performance sensors located at the line of sight is implemented within the proposed framework, to improve the performance of the estimate at the location of the lower performance sensor. The fusion framework makes use of cascaded Multiplicative Extended Kalman Filter that estimate the multiplicative error of the quaternion orientation estimate