Study Of Lunar Constellations For Situational Awareness And Surveillance

Lunar constellations providing the capabilities of situational awareness and surveillance for future mission operators are analyzed in this study. The use of specialty orbits, such as sun-synchronous and frozen orbits, are analyzed to determine the applicability of these unique orbits. Additionally, altitude and inclination trades are performed to determine the degree to which mission objectives are achieved through ranges of these orbital parameters. Using the analyzed orbits, constellations of varying patterns are developed and surface coverage figures of merit are used to evaluate them. The research concludes with calculation of the yearly cross-track and in-track stationkeeping costs of a representative constellation. This stationkeeping is necessary for preservation of the designed coverage statistics

On-Orbit Performance of the BCT XB-1 Spacecraft and GN&C Components

Blue Canyon Technologies (BCT) currently has a variety of hardware operating in space with multiple missions launched in 2016. The deployment of the Miniature X-ray Solar Spectrometer (MinXSS) 3U CubeSat from ISS on May 16, 2016 was the first mission to operate the high accuracy pointing, complete GN&C subsystem XACT. The first on-orbit operation of the BCT XB-1 spacecraft bus occurred with the launch of the APL Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) 3U Cubesat on November 11, 2016. Finally, the NASA Cyclone Global Navigation Satellite System (CYGNSS) constellation of eight microsatellites was deployed from an Orbital ATK Pegasus XL rocket on December 15, 2016 and each spacecraft has a BCT Nano Star Tracker and three p015 reaction wheels. This paper reviews on-orbit performance of these components and systems. Detailed analysis of on-orbit telemetry is used to assess performance, with an emphasis on pointing accuracy but also including momentum control, safe mode operations, and other aspects. The results indicate a variety of solutions, ranging from high performing GN&C components to a complete spacecraft bus, capable of providing high-accuracy pointing for small satellites

Small Projects Rapid Integration and Test Environment (SPRITE): Application for Increasing Robutness

Over the past few years interest in the development and use of small satellites has rapidly gained momentum with universities, commercial, and government organizations. In a few years we may see networked clusters of dozens or even hundreds of small, cheap, easily replaceable satellites working together in place of the large, expensive and difficult-to-replace satellites now in orbit. Standards based satellite buses and deployment mechanisms, such as the CubeSat and Poly Pico-satellite Orbital Deployer (P-POD), have stimulated growth in this area. The use of small satellites is also proving to be a cost effective capability in many areas traditionally dominated by large satellites, though many challenges remain. Currently many of these small satellites undergo very little testing prior to flight. As these small satellites move from technology demonstration and student projects toward more complex operational assets, it is expected that the standards for verification and validation will increase

The B-dot Earth Average Magnetic Field

The average Earth's magnetic field is solved with complex mathematical models based on mean square integral. Depending on the selection of the Earth magnetic model, the average Earth's magnetic field can have different solutions. This paper presents a simple technique that takes advantage of the damping effects of the b-dot controller and is not dependent of the Earth magnetic model; but it is dependent on the magnetic torquers of the satellite which is not taken into consideration in the known mathematical models. Also the solution of this new technique can be implemented so easily that the flight software can be updated during flight, and the control system can have current gains for the magnetic torquers. Finally, this technique is verified and validated using flight data from a satellite that it has been in orbit for three years

Small Project Rapid Integration and Test Environment (SPRITE) An Innovation Space for Small Projects Design, Development, Integration, and Test

Over the past few years interest in the development and use of small satellites has rapidly gained momentum with universities, commercial, and government organizations. In a few years we may see networked clusters of dozens or even hundreds of small, cheap, easily replaceable satellites working together in place of the large, expensive and difficult-to-replace satellites now in orbit. Standards based satellite buses and deployment mechanisms, such as the CubeSat and Poly Pico-satellite Orbital Deployer (P-POD), have stimulated growth in this area. The use of small satellites is also proving to be a cost effective capability in many areas traditionally dominated by large satellites, though many challenges remain. Currently many of these small satellites undergo very little testing prior to flight. As these small satellites move from technology demonstration and student projects toward more complex operational assets, it is expected that the standards for verification and validation will increase

Lifetime Lubricant Use among a Nationally Representative Sample of Lesbian- and Bisexual-Identified Women in the United States

Introduction The diversity in self-identified lesbian and bisexual women's sexual interactions necessitates better understanding of how and when they integrate personal lubricant into different experiences. However, little is known about lesbian and bisexual women's lifetime lubricant use, particularly at the population level. Aims The aim of this study was to examine the prevalence and characteristics of lubricant use among adult lesbian and bisexual women in the United States. Methods Data were drawn from a subset of lesbian and bisexual participants who participated in the 2012 National Survey of Sexual Health and Behavior, an online questionnaire administered to a nationally representative probability sample of U.S. adults ages 18 and older. Main Outcome Measures We examined socio-demographic characteristics, recent and lifetime lubricant use, lubricant use in associated with specific sexual behaviors and condom use, frequency of use, motivations for use, as well as perception of lubricant when used. Results A majority of lesbian- (60.1%) and bisexual-identified (77.1%) women reported ever using lubricant; 25.7% of lesbian women and 32.7% of bisexual women used it in the last 30 days. Across most age groups, lubricant was commonly used during partnered sexual play, partnered sexual intercourse, or when a vibrator/dildo was used. Lesbian and bisexual women reported using lubricants to increase arousal/sexual pleasure/desire, to make sex more fun, or to increase physical comfort during sex. Conclusions Lubricant use is identified as a part of lesbian and bisexual women's sexual experience across the life span, as a part of both solo and partnered experiences. As part of evolving sexual health assessments, clinicians and health educators may find value in integrating lubricant-focused conversation with their lesbian and bisexual patients and clients, particularly

Identifying Rural Salience in the 2020 Whippoorwill Book Award Winners

About the winners of the 2020 Whipporwill Award

Pushing the Limits of Cubesat Attitude Control: A Ground Demonstration

A cubesat attitude control system (ACS) was designed at the NASA Marshall Space Flight Center (MSFC) to provide sub-degree pointing capabilities using low cost, COTS attitude sensors, COTS miniature reaction wheels, and a developmental micro-propulsion system. The ACS sensors and actuators were integrated onto a 3D-printed plastic 3U cubesat breadboard (10 cm x 10 cm x 30 cm) with a custom designed instrument board and typical cubesat COTS hardware for the electrical, power, and data handling and processing systems. In addition to the cubesat development, a low-cost air bearing was designed and 3D printed in order to float the cubesat in the test environment. Systems integration and verification were performed at the MSFC Small Projects Rapid Integration & Test Environment laboratory. Using a combination of both the miniature reaction wheels and the micro-propulsion system, the open and closed loop control capabilities of the ACS were tested in the Flight Robotics Laboratory. The testing demonstrated the desired sub-degree pointing capability of the ACS and also revealed the challenges of creating a relevant environment for development testi

The 2023 Whippoorwill Award: The 2023 Whippoorwill Award: Complex Representations of Rural Identities and Places

Announcing the 2023 Whippoorwill Award winners