Telemetry Fault-Detection Algorithms: Applications for Spacecraft Monitoring and Space Environment Sensing

Telemetry Fault-Detection Algorithms: Applications for Spacecraft Monitoring and Space Environment Sensing Carlton, Ashley; Morgan, Rachel; Lohmeyer, Whitney; Cahoy, Kerri Algorithms have been developed that identify unusual behavior in satellite health telemetry. Telemetry from solid-state power amplifiers and amplifier thermistors from 32 geostationary Earth orbit communications satellites from 1991 to 2015 are examined. Transient event detection and change-point event detection techniques that use a sliding window-based median are used, statistically evaluating the telemetry stream compared to the local norm. This approach allows application of the algorithms to any spacecraft platform because there is no reliance in the algorithms on satellite- or component-specific parameters, and it does not require a priori knowledge about the data distribution. Individual telemetry data streams are analyzed with the event detection algorithms, resulting in a compiled list of unusual events for each satellite. This approach identifies up to six events of up to six events that affect 51 of 53 telemetry streams at once, indicative of a spacecraft system-level event. In two satellites, the same top event date (4 December 2008) occurs over more than 10 years of telemetry from both satellites. Of the five spacecraft with known maneuvers, the algorithms identify the maneuvers in all cases. Event dates are compared to known operational activities, space weather events, and available anomaly lists to assess the use of event detection algorithms for spacecraft monitoring and sensing of the space environment.

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Design of the Deformable Mirror Demonstration CubeSat (DeMi)

Design of the Deformable Mirror Demonstration CubeSat (DeMi) Douglas, Ewan; Allan, Gregory; Barnes, Derek; Figura, Joseph S.; Haughwout, Christian A.; Gubner, Jennifer N.; Knoedler, Alex A.; LeClair, Sarah; Murphy, Thomas J; Nikolaos, Skouloudis; Merk, John; Opperman, Roedolph A.; Cahoy, Kerri L. The Deformable Mirror Demonstration Mission (DeMi) was recently selected by DARPA to demonstrate in-space operation of a wavefront sensor and Microelectromechanical system (MEMS) deformable mirror (DM) payload on a 6U CubeSat. Space telescopes designed to make high-contrast observations using internal coronagraphs for direct characterization of exoplanets require the use of high-actuator density deformable mirrors. These DMs can correct image plane aberrations and speckles caused by imperfections, thermal distortions, and diffraction in the telescope and optics that would otherwise corrupt the wavefront and allow leaking starlight to contaminate coronagraphic images. DeMi is provide on-orbit demonstration and performance characterization of a MEMS deformable mirror and closed loop wavefront sensing. The DeMi payload has two operational modes, one mode that images an internal light source and another mode which uses an external aperture to images stars. Both the internal and external modes include image plane and pupil plane wavefront sensing. The objectives of the internal measurement of the 140-actuator MEMS DM actuator displacement are characterization of the mirror performance and demonstration of closed-loop correction of aberrations in the optical path. Using the external aperture to observe stars of magnitude 2 or brighter, assuming 3-axis stability with less than 0.1 degree of attitude knowledge and jitter below 10 arcsec RMSE, per observation, DeMi will also demonstrate closed loop wavefront control on an astrophysical target. We present an updated payload design, results from simulations and laboratory optical prototyping, as well as present our design for accommodating high-voltage multichannel drive electronics for the DM on a CubeSat.

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Using the Galileo Solid-State Imaging Instrument as a Sensor of Jovian Energetic Electrons

Using the Galileo Solid-State Imaging Instrument as a Sensor of Jovian Energetic Electrons Carlton, Ashley; de Soria-Santacruz Pich, Maria; Kim, Wousik; Jun, Insoo; Cahoy, Kerri We quantitatively describe the Jovian energetic electron environment using the Solid State Imager (SSI) on the Galileo spacecraft. We post-process raw SSI images by removing the target object and dark current to obtain frames only with the radiation contribution. The camera settings (gain state, filter, etc.) are used to compute the energy deposited in each pixel, which corresponds to the intensity of the observed radiation hits (the actual measurements are expressed with the digital number (DN), from which the energy deposited can be computed). Histograms of the number of pixels versus energy deposited by incident particles from processed SSI images are compared with the results from 3D Monte Carlo transport simulations of the SSI using Geant4. We use Geant4 to simulate the response of the SSI instrument to mono-energetic electron environments from 1 to 100 MeV. We fit the modeled instrument response to the SSI data using a linear combination of the simulated mono-energetic histograms to match the SSI observations. We then estimate the spectra of the energetic electron environment at Jupiter, or we estimate the integral flux when there is lower confidence in the spectra fits. We validate the SSI results by comparing the environment predictions to the observations from the Energetic Particle Detector (EPD) on the Galileo spacecraft, examining the electron differential fluxes from 10’s of keV to 11 MeV. For higher energies (up to 31.0 MeV), we compare our findings with the NASA GIRE model, which is based on measurements from the Pioneer spacecraft. This approach could be applied to other sets of imaging data in energetic electron environments, such as from star trackers in geostationary Earth orbits.

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Sensory Motor Conflict Theory for Motion Sickness: Oman letter to Reason

Sensory Motor Conflict Theory for Motion Sickness: Oman letter to Reason Oman, Charles M. CM Oman (MIT) letter to JT Reason (U. Manchester) describing Sensory Motor Conflict Theory for motion sickness, as initially presented at NASA Vestibular Motion Sickness Workshop at Johnson Space Center November, 1978, and later elaborated in Oman, C. M. (1982). "A heuristic mathematical model for the dynamics of sensory conflict and motion sickness." Acta Otolaryngologica (Stockholm) 94(S392): 4-44.

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Analysis of aero-elastic forces in labyrinth seals and the design of an experimental facility to measure them

Analysis of aero-elastic forces in labyrinth seals and the design of an experimental facility to measure them Millsaps, Knox Taylor Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics.; Bibliography: leaves 134-138.

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Market share model for a multi-airport system

Market share model for a multi-airport system Cohas, François Because capacity at existing airports was limited and/or because the cost of congestion was becoming unacceptable, several large cities around the world have had to build a second or third major commercial airport to keep up with the demand for air transportation. Such groups of competing airports are called multi-airport systems (M.A.S.) There is extensive historical evidence suggesting that multi-airport systems have often been poorly understood, resulting in disastrous investments such as the construction of airports that remained underused for very long periods of time. The purpose of this paper is to provide a better understanding of the ways M.A.S.s function. First, we consider qualitative characteristics of multi-airport systems, showing the importance of market forces. Then, we build an airport market share model that captures the dynamics of the market, where airlines and air passengers select an airport on the basis of a broad range of factors. Case studies are carried out for several origin-destination markets out of three large metropolitan areas: New York, Washington-Baltimore, and the San Francisco Bay Area. The results show that an airport market share can be well approximated by using few explanatory variables: frequency of service and average fare at the designated airport, and average fare at competing airports. In spite of the relative simplicity of our statistical model, we obtain a good fit between observed and predicted market shares. The explanatory variables are statistically significant and the estimated elasticities (direct price, frequency, and cross-price) are consistent with intuition. We conclude by highlighting the limitations of the model and by suggesting some implications concerning the construction of new airports in metropolitan areas and the potential for regional airports to alleviate the congestion problems at large metropolitan airports. Cover title; June 1993; Includes bibliographical references (pages 149-152)

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Analysis of aircraft fleets of U.S. major airlines since deregulation

Analysis of aircraft fleets of U.S. major airlines since deregulation Ferrer José The purpose of this thesis is to relate the U.S. Major airlines changing use of aircraft to aviation policy and technology since deregulation of the U.S. airline industry enacted in 1978. First, a study of the airline fleet mix was carried out in order to understand how airlines have composed their fleets in the past and how they are preparing for the future. Airlines have responded very favorably to any changes in aircraft characteristics that have the potential to lower operational costs, such as the introduction of two-crew member cockpits and the acquisition of twin-engined aircraft whenever possible. Airline fleets are primarily made up of low capacity/short range aircraft, which is an indication of airlines concentrating in domestic markets where frequency of service is critical. The shift towards the usage of more fuel efficient and quieter aircraft engines is evident. How the airlines actually operated their aircraft fleets in both domestic and international markets was also examined. The analysis focused on relating aircraft characteristics with the aircraft operation data published by the United States Department of Transportation. It was found that these airlines have concentrated their operations mostly in the domestic arena, representing 84.6% of total aircraft miles flown at the beginning of deregulation in 1978 and only decreasing to 84.1 % by 1990. There has been an increase of 70% in the total number of miles flown. The cause for this growth can be attributed to numerous airline mergers, and the expansion to the international arena in search of new markets. In addition, airlines are flying their aircraft further. Traffic results indicate that aircraft may have been scheduled more cycles per day and that air traffic congestion has been increasing since deregulation. Cover title; Vita; Includes bibliographical references

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Tradespace Investigation of a Telescope Architecture for Next-generation Space Astronomy and Exploration

Tradespace Investigation of a Telescope Architecture for Next-generation Space Astronomy and Exploration Cataldo, Giuseppe; Chodas, Mark; Dave, Pratik; Dixit, Atray; Hall, Sherrie; Harris, Robert; Hayhurst, Dustin; Hicks, Fernando; Jewison, Christopher; Josan-Drinceanu, Ioana; Karlow, Brandon; McCarthy, Bryan; Owens, Andrew; Peters, Eric; Shaw, Margaret; Sternberg, David; Voelbel, Kathleen; Wu, Marcus Humanity’s endeavor to further its scientific understanding of the celestial heavens has led to the creation and evolution of increasingly powerful and complex space telescopes. Space telescopes provide a view of the solar system, galaxy, and universe unobstructed by Earth’s atmosphere and have profoundly changed the way people view space. In an effort to further advance space telescope capability and achieve the accompanying scientific understanding, the Massachusetts Institute of Technology (MIT), specifically, course 16.89 Space Systems Engineering, explored the tradespace of architectural enumerations encompassed within the design of an ultraviolet-optical-infrared (UVOIR) space telescope located at Sun-Earth Lagrangian Point Two (SE-L2). SE-L2 presents several advantages as an operating location for a UVOIR telescope such as a thermally stable environment and an orbit that allows the telescope to maintain a constant orientation with respect to all of the primary sources of heat and light. The main disadvantages associated with SE-L2 are caused by its relatively large distance from Earth, which marginalizes the effectiveness of real-time telerobotics because of latency and increases the cost of communications, launch, and servicing. Course 16.89 believes that, for this UVOIR application, the strengths of this operating location outweigh its weaknesses and therefore decided to explore the family of opportunities associated with SE-L2. This course used appropriate performance and system metrics to quantify the effectiveness of the aforementioned architectures and create a Pareto front of viable architectures. Evaluating the designs along the Pareto front allowed the course to characterize and group architectures and present these group-types to stakeholders for the selection of an optimal space telescope according to stakeholder requirements and resources. This course also developed sensitivity analysis, which allowed for a greater understanding of how architectural decisions affect the performance of the satellite. Segmentation, modularity, assembly, autonomy, and servicing were key aspects of this multidimensional analysis given the 16.8-meter class size and location of the telescope. Within the respective operating environment and for a spacecraft of similar characteristics, this model will allow stakeholders to predict the long-term operational effectiveness of different space telescope architectures and capture the synergistic effects of combining various architectural decisions into a spacecraft design. The following sections step through the aforesaid analysis and design efforts conducted in 16.89 beginning with Section III, which explicitly performs the stakeholder analysis and articulates the requirements of the mission. Section IV gives an overview of past designs and expands upon the architecture enumerations pertinent to this project, while Section V presents the methods and metrics by which those architectures will be evaluated and the system metrics which will be balanced and optimized in the creation of this space telescope. Section VI will present the model validation of this project and Section VII will discuss the results and analyses of the project. Finally, Section VIII will explore the future work opportunities of this project, while Section IX will present the conclusions and recommendations drawn from this project.



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