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search.filters.applied.f.advisor: Lightsey, E. Glenn × End date: 2020 × Start date: 2020 ×

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Now showing 1 - 7 of 7
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Payload System Design of a CubeSat Distributed Telescope

2020-12-10 , Thatavarthi, Rohan

The Virtual Super-Resolution Optics with Reconfigurable Swarms (VISORS) mission is a novel CubeSat formation distributed telescope mission that aims to investigate the underlying energy release mechanisms in the solar corona. VISORS is a mission that was initially conceived in the National Science Foundation (NSF) CubeSat Innovations Ideas Lab workshop held in 2019. The mission will observe the corona in extreme ultra-violet (EUV) at an angular resolution of less than 0.2 arcseconds using two 6U CubeSats that align and fly 40 meters apart to form a distributed telescope. Achieving such a mission requires key technologies in the fields of diffractive optics, inter-satellite communication, CubeSat propulsion, and relative navigation. The development of any single one of these technologies is novel but all of them working in conjunction truly enables the VISORS mission. The consolidation of these technologies into the Cubesat form factor poses a mechanical and systems design challenge. This paper focuses on the preliminary payload design of the VISORS CubeSats, the challenges inherent with combining the key technologies into a 6U form factor, and the key next steps to mature the payload design. Working in conjunction with 10 different universities and a projected launch in late 2023, the VISORS mission will demonstrate the capabilities of CubeSats to perform high precision coronal imagery and will pave the path forward for future CubeSat swarm missions.

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Development of a Cubesat-Scale Green Monopropellant Propulsion System for NASA’s Lunar Flashlight Mission

2020-07-29 , Huggins, Grayson

NASA’s Lunar Flashlight is a low-cost 6U CubeSat whose mission is to search for ice and mineral deposits inside of the scattered craters at Moon’s southern pole. To conduct its primary science mission, Lunar Flashlight must be placed in a stable lunar polar orbit which requires utilization of an on-board propulsion system. However, to this date most CubeSats have been propelled by cold-gas or electric propulsion systems that have proven to scale well, but are not efficient or impulsive enough to conduct large Δ𝑉 maneuvers such as orbit insertions. To this end, the Lunar Flashlight mission has chosen to utilize a custom-designed green monopropellant propulsion system developed by the Georgia Institute of Technology under the sponsorship and guidance of NASA’s Marshall Spaceflight Center and Jet Propulsion Laboratory. The developed system is capable of providing more than the required propulsive capability for full mission success while fitting inside of a 2.5U volume and weighing less than six kilograms. The system is developed for use with the AF-M315E green monopropellant that provides higher specific impulse compared to traditional hydrazine while also being safer to handle. If successful, the presented propulsion system will enable Lunar Flashlight to be the first CubeSat to reach the Moon, the first to conduct an orbit insertion, and will be the second-ever spaceflight demonstration of the AF-M315E propellant.

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Design of the Attitude Estimation Algorithms for the GT-1 CubeSat

2020-05-01 , Guecha-Ahumada, Nelson G.

GT-1 is the first of four 1U CubeSats under development by the Georgia Institute of Technology’s Space Systems Design Laboratory (SSDL). Its main objective is to prove the feasibility of an inexpensive spacecraft bus designed and fabricated by students in just over a year. Given the mass, volume and cost constraints; the sensor suite is limited to low-cost Commercial-Off-The-Shelf (COTS) components such as Coarse Sun Sensors, a Magnetometer, an Inertial Measurement Unit (IMU), and a Global Positioning System (GPS) receiver. A 6-Degree-of-Freedom (6-DOF) simulation of GT-1 was created to develop sensor models and estimation algorithms. Two static attitude determination methods, TRIAD and Davenport’s Q Method were developed and evaluated using the 6-DOF simulation. In addition, an Extended Kalman Filter (EKF) was developed using the same simulation environment to provide a sequential attitude estimation framework capable of propagating the attitude dynamics and correcting the attitude estimate. This document acts as a survey of reliable attitude estimation techniques and algorithms that can be implemented on an elementary mission profile based on a modest sensor suite

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Manufacturing, Integration, and Testing of the Green Monopropellant Propulsion System for NASA’s Lunar Flashlight Mission

2020-12 , Talaski, Ali

NASA’s Lunar Flashlight is a 6U CubeSat that will be investigating the Lunar South Pole for water-ice. Propelling the spacecraft is a 2.5U green monopropellant propulsion system developed by the Georgia Tech Space Systems Design Laboratory in partnership with the NASA Marshall Spaceflight Center and NASA Jet Propulsion Laboratory. Lunar Flashlight will be the first interplanetary CubeSat to use green propulsion, and will be the first CubeSat to place itself into orbit around another planetary body. Utilizing a mix of traditional and additive manufacturing techniques to manufacture the propulsion system presented unique challenges for the project. In addition, the integration of precision flight hardware has required rapid design changes to parts to ensure that the system fits together as intended. However, as a pathfinder mission for future small satellite propulsion systems, the Lunar Flashlight Propulsion System will establish flight heritage of various components, including additively manufactured hardware, microfluidic components, custom-designed electronics, and unique cleanliness specifications.

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Vertical Entry Robot for Navigating Europa (VERNE)

2020-05-01 , Szot, Phillip

The goal of the Vertical Entry Robotic Navigation of Europa (VERNE) mission is to explore the ice shelves and water reservoirs of Europa in support of the search for signs of life. Europa is widely regarded as one of the best candidates in the solar system for finding past or present signs of life. As new technologies are matured over the coming decades, this type of mission becomes possible. It is the goal of this mission concept study to establish a vehicle and mission architecture that maximizes the likelihood of overall mission success from landing to end-of-life. This study will highlight modern day technologies that will enable the mission to be completed as well as highlight technology gaps that need to be filled before this type of mission will be fully possible. This mission concept study is being performed for the Subsurface Access Mechanism for Europa (SESAME) program [5]. Under the terms of this concept study, VERNE will already have been provided with the necessary support to proceed from launch to landing on Europa. Once landed, the probe will travel toward the under-ice water reservoirs, conducting life finding science and geochemistry measurements both along the way and at the ice-ocean interface. This is highlighted in the Mission CONOPS Diagram shown in Figure 1. This mission will be the first of its kind, so novel architecture and new subsystem designs are a necessity.

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Simulation and Dynamic Modeling of a Thermomechanical Ice Probe

2020-12-01 , Daniel, Nathan L.

Ice-penetrating probes are useful tools for research on Earth, particularly for studying liquid water underneath or surrounded by ice. In recent decades, interest has grown in the use of ice probes for exploring the subsurface oceans thought to exist on some of the Solar System’s icy worlds. While much work has been done on the thermal power requirements of such probes, little modeling work has been published on hybrid thermomechanical drilling probes. In this paper, a method is developed for simulating the descent trajectory of a hybrid thermomechanical probe through the ice shell of Jupiter’s moon Europa. This method com bines independent calculations of the velocity contributions from drilling and melting and a strategy for determining the conditions required for melting. Trajectories and descent time estimates are given for a range of different assumptions. Finally, the problem of melt probe attitude stability is briefly discussed and initial modeling efforts are presented.

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CubeSat Slosh Dynamics and Its Effect on Precision Attitude Control for the VISORS Distributed Spacecraft Telescope Mission

2020-05-01 , Carter, Christopher A.

The VIrtual Super Optics Reconfigurable Swarm (VISORS) mission is a CubeSat distributed telescope mission which aims to take high angular resolution images of the sun using multiple spacecraft in sub 100m proximity operations. This requires high accuracy attitude and relative position control on small time scales. To achieve the required relative position accuracy, the spacecraft in the swarm must frequently use thrusters to provide impulsive corrections. This paper examines the effect that these maneuvers have on the CubeSat attitude control system by examining the relative magnitudes of each force acting on the system and choosing applicable analytic methods to predict the fundamental characteristics of the response. These characteristics were used to inform an analogous mechanical model for the slosh motion, which was used to determine the time-varying response of the spacecraft control system while considering slosh disturbances. By simulating typical maneuvers, the spacecraft’s sensitivity to slosh disturbances was determined, providing operational constraints and initial validation of the mission’s precise pointing requirements.

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