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Graduate STEM Fellow Profile

Jessica Alvarenga

Project Title: IMPACT LA: Improving Minority Partnerships and Access through CISE-related Teaching
Thesis: Kalman Filtering for a Large Monolithic Segmented Telescope Testbed
College/University: California State University, Los Angeles
Research Advisor: Dr. Helen Ryaciotaki-Boussalis
Degree Sought: Masters in Electrical Engineering
Department: Electrical Engineering / NASA URC SPACE Center
Research Focus: Control Algorithms for Large Scale Dynamic Systems
Teaching Partner(s): Adriana Trejo Sanchez

Description of Research

With the increasing need to see further into space than can be achieved by current technology, such as the Hubble Telescope, it becomes necessary to increase the size of the primary mirror of a space telescope. However, there are several problems when increasing the size of the primary mirror. As mirror size increases, manufacturing a precise paraboloid mirror becomes more difficult. The size of a single monolithic primary mirror is restricted by the size and weight limitations of the current space launch vehicles. Future missions, such as the James Webb Space Telescope (JWST) will employ a segmented primary mirror to overcome these difficulties.
The NASA URC Space Center team has developed a telescope testbed which emulates a Cassegrain telescope of 2.4 meter focal length with performance comparable to actual space-borne systems. It consists of a primary mirror made from seven hexagonal panels (6 peripheral and one center stationary), a secondary mirror and lightweight flexible truss structure. Each peripheral panel is controlled by three linear electromagnetic actuators. Four edge position sensors are used per panel are used to provide relative displacement and angle. The secondary mirror, a six-sided pyramidal mirror, is used to reflect the light from the primary mirror to the focal plane.
A large scale system, such as the telescope testbed, requires reliable methods of real time state estimation for system monitoring, fault detection and isolation, tracking of system and component degradation, and prediction. Given that a space-based telescope such as the JWST will not be serviceable once in space, it is critical for such a system to maintain performance requirements in the presence of disturbances and noise. The Kalman Filter algorithm allows for state estimation of a process or system in the presence of disturbances and noise. The filter is a recursive numerical method which requires knowledge of the previous states and current measurements. The current research will improve upon the established method of state estimation and fault detection by development and incorporation of a Kalman Filter algorithm directly applicable to the SPACE testbed.

Example of how my research is integrated into my GK-12 experience

Much of my research involves very complex ideas and math as well as an appreciation of space exploration and aerospace. Very few of the students I have had the pleasure of working with have had very little, if any exposure to these topics. In introducing my research to the students, I felt it was first important for them to build an appreciation for why such research needs to be performed. By using scaffolding, I have worked backwards to bring top level ideas into the classroom and then build up to more detailed concepts. For AP Statistics, I introduced the students to the James Webb Space Telescope’s predecessor, the Hubble Space Telescope, and had the students design a sampling plan to create a guess at the frequency of various galaxy types in the universe. The idea of satellites and telescopes was introduced to Pre-calculus using a GPS activity and Google Earth, to show applications and benefits to having such technology. With each activity, I introduce conceptual how that applies to my research specifically.

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