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At least 271 records · Page 15

Rapid Development of the Seeker Free-Flying Inspector Guidance, Navigation, and Control System

Seeker is an automated extravehicular free-flying inspector CubeSat designed and built in-house at the Johnson Space Center (JSC). As a Class 1E project funded by the International Space Station (ISS) Program, Seeker had a stream-lined process to flight certification, but the vehicle had to be designed, developed, tested, and delivered within approximately one year after authority to proceed (ATP) and within a $1.8 million budget. These constraints necessitated an expedited Guidance, Navigation, and Control (GNC) development schedule. Development began with a navigation sensor trade study using Linear Covariance (LinCov) analysis and a rapid sensor down-selection process, resulting in the use of commercial off-the-shelf (COTS) sensors which could be procured quickly and subjected to in-house environmental testing to qualify them for flight. A neural network was used to enable a COTS camera to provide bearing measure-ments for visual navigation. The GNC flight software (FSW) algorithms utilized lean development practices and leveraged the Core Flight Software (CFS) architecture to rapidly develop the GNC system, tune the system parameters, and verify performance in simulation. This pace was anchored by several Hardware-Software Integration (HSI) milestones, which forced the Seeker GNC team to develop the interfaces both between hardware and software and between the GNC domains early in the project and to enable a timely delivery.

Sullivan, Jake↗

BioSentinel: To the Moon or Beyond?

BioSentinel, an Artemis-1 secondary spacecraft, will carry a biology experiment into deep space for the first time in 50 years. A 6U CubeSat form factor was utilized for the spacecraft and included technologies newly developed or adapted for operations beyond Earth orbit. This is the maiden deep-space voyage for the radio, propulsion system, electrical power system, and BioSensor payload. The spacecraft carries onboard budding yeast, Saccharomyces cerevisiae, as an analog to human cells to test the biological response to deep space radiation. Flying a secondary payload beyond LEO comes with unique challenges with respect to trajectory uncertainty and mission operations planning. BioSentinel does not carry propulsion for trajectory maneuvers, so plans for Comms and Power need to be developed for all trajectories. The nominal plan is a lunar flyby followed by an insertion into Heliocentric orbit. However, some possible scenarios include lunar eclipses that could severely impact the power budget during that phase of the mission, while others could result in a “Retrograde” hyperbola at swingby resulting in the spacecraft traveling inward toward Earth or even towards a collision with the lunar surface. BioSentinel’s final trajectory will not be known until after launch and deployment so possible scenarios need to be planned for ahead of time. This paper discusses the operational scenarios that were planned for as well as the actual execution of the mission operations including: command pass scheduling with the Deep Space Network, selecting bandwidth limits, medium gain antenna versus low gain antenna usage, and conserving power prior to a lunar eclipse. Note: Artemis-1 is planned to launch in the Spring of 2022

BioSentinel↗

A Status of U-Class Earth Science Instruments at JPL

With advancements in CubeSat technologies and low-cost launch opportunities, CubeSats could play a role in meeting NASA’s key Earth science measurement objectives, especially in extreme weather and ecosystem processes. In this paper, we discuss the development of “science grade” hyperspectral imager, microwave spectrometer, IR sounder, and Ka-band radar instruments at JPL. They are scheduled to launch in early to late 2018 while the hyperspectral imager is being developed for airborne flights and for space in the future. The limitations in power, mass, and volume imposed by the CubeSat platform required the identification of new technologies in order to miniaturize instruments into a specific form factor. In conclusion, we will summarize strategies to implement small and low-cost instruments and suggest an architecture for enabling a constellation of U-class instruments.

Hyon, Jason J.↗

Passive Thermal Coating Observatory Operating in Low-Earth Orbit (PATCOOL) – Cubesat Design to Test Passive Thermal Coatings in Space

The PATCOOL is a NASA sponsored, University of Florida developed 3U Cu-beSat meant to investigate the feasibility of using a cryogenic selective surface coating as a new, more efficient way of passively cooling components in space. Initial tests on the ground demonstrate that this coating should provide a much higher reflectance of the Sun’s irradiant power than any existing coating, while still providing far-infrared power emission. The ultimate validation of this tech-nology requires on-orbit testing. PATCOOL hosts a 4-sample housing, with the samples shaped as thin cylinders (coin-like). Two samples are coated with state-of-the-art material, while the other pair uses the new coating to be evaluated. The temperatures of all samples during the mission (minimum 72 hours of data col-lection) are measured via thermistors. The samples are connected via thin Kevlar strings to the housing, to minimize heat transfer. The housing is designed to shield the samples from Earth’s thermal radiation, and the CubeSat is attitude stabilized and controlled via a gravity gradient boom, magnetorquers and a reaction wheel set. Thermal Desktop simulations show PATCOOL’s ability to thermally isolate the samples from heat exchanges other than with Sun and deep space, thanks to its thermal design and the chosen attitude profile.

Ojeda, Carlos↗

Infrastructure and Process Improvements After LADEE

The purpose of the Lunar Atmosphere Dust Environment Explorer (LADEE) mission was to measure the density, composition and time variability of the lunar dust environment. The successful mission launched Sept 7, 2013 and was de-orbited and impacted the moon's surface on April 17, 2014. The spacecraft had 3 primary science instruments, the Lunar Dust Experiment, Neutral Mass Spectrometer, and the Ultra Violet Spectrometer. The mission also had a Laser Communications payload that set a record download rate of 622 Mbps (megabits per second) from the moon orbit. The goal is to use the LADEE software base for upcoming smallsat missions. The onboard flight software for the mission was developed using a Model-Based Software methodology and agile software development practices. High level models were developed in Simulink, autocoded to C and layered on Core Flight Executive and Core Flight Software, VxWorks and required board support packages. Software package versions were frozen several years ago, and need to be brought to modern standards for future spacecraft missions. We are evaluating alternate Real Time Operating Systems and avionics architectures that comply with CubeSat form-factor and power limitations. In addition, the tool chain for the software development process has been improved. We will discuss the rationale, trades and implementation for the upgrade path after the LADEE mission.

Software Maintenance↗

Development of a Universal Small-Satellite Payload for On-Orbit Characterization and Evaluation of Novel Radiation-Shielding Materials

There is a need for novel lightweight radiation shielding materials for small satellites operating in LEO and beyond. Current commonly used shielding materials include aluminum and polyethylene, though often no additional shielding than that provided by structure is used due to mass and dimensional constraints. New materials are being developed which may offer advantages over these current solutions. These materials include novel lightweight composites impregnated with metallic nanoparticles, chitin-derived bioplastics, and aerogel-family materials. A compact CubeSat experiment payload that allows the simultaneous testing of numerus potential shielding materials would be useful to enable material comparison and efficacy validation. An effort currently underway seeks to develop such a miniaturized modularized payload, which will enable the testing of materials in 1U CubeSat form factor modules, with each module hosting four scintillator radiation detectors arrayed behind four sample material windows exposed to space. The first proposed mission will utilize a 2U payload volume to host two test quartets enabling eight materials to be tested. Such a test platform can potentially be used as a hosted payload on a variety of spacecraft to test additional materials in the future

Luke Idziak↗

RainCube, a Ka-band Precipitation Radar in a 6U CubeSat

RainCube (Radar in a CubeSat) is a 6U CubeSat mission between the Jet Propulsion Laboratory (JPL) and Tyvak Nano-Satellite Systems (Tyvak). The objective of the mission is to develop, launch, and operate a 35.75 GHz nadirpointing precipitation profiling radar payload to validate a new architecture for Ka-band radars and an ultra-compact deployable Ka-band antenna design in the space environment. RainCube will also demonstrate the feasibility of a radar payload on a CubeSat platform. The radar payload is the evolution of two previous JPL research and development technologies – the miniaturized Ka-band atmospheric radar (miniKaAR) and the 0.5m diameter Ka-band parabolic deployable antenna (KaPDA). JPL has contracted Tyvak to develop the spacecraft bus, integrate the payload, and operate the spacecraft. RainCube is currently in integration and test with an expected ready-for-delivery in September 2017.

Williams, Austin↗

NASA Facts: Edison Demonstration of Spacecraft Networks (EDSN) Mission

NASA's Edison Demonstration of Smallsat Networks (EDSN) mission will launch and deploy a swarm of 8 cubesats into a loose formation approximately 500 km above Earth. EDSN will develop technology to send multiple, advanced, yet affordable nanosatellites into space with cross-link communications to enable a wide array of scientific, commercial, and academic research. Other goals of the mission include lowering the cost and shortening the development time for future small spacecraft.

Ord, Stephen↗

Applications of Fracture Mechanics to Quantitative Accelerated Life Testing of Plastic Encapsulated Microelectronics

Accelerated testing must address the failure mechanisms active within the devices undergoing tests in order to assess lifetimes in a meaningful way. The assumption of constant temperature, thermally activated lifetime, based upon the Arrhenius assumptions, does not always provide the necessary understanding to interpret accelerated tests in microelectronics. Plastic encapsulants, dielectric polymers, and underfill materials are subject to delamination and cracking with thermal cycling. Crack propagation during use environment exposure, drives the potential for failure of microelectronic devices and is therefore a necessary focal point in qualification and life testing. This paper reviews the available research in the application of fracture mechanics to this class of problems in microelectronics including relevant test data. In addition, useful acceleration factor models are derived for polymer crack propagation based on principles of linear elastic fracture mechanics. Further, a simple approach to estimating the minimum temperature cycling ranges, necessary to propagate a crack, is also presented. Finally, a methodology of applying acceleration factors to develop testing plans is shown, with an example in spaceflight for a cubesat in low Earth orbit. Overall, this is a paper that shows a useful and appropriate process for creating physics of failure based life testing for delamination and cracking failures in microelectronic polymers in a temperature cycling environment.

Accelerated testing↗

Automating Maneuvers: Considerations for Collision Avoidance

As more space operators implement large constellations of spacecraft, automating orbit maintenance maneuvers becomes a key feature of their operations concept to ensure that the workload is manageable. However, the practice of performing a maneuver without sharing the plan with other nearby spacecraft causes a risk that two spacecraft will collide, not only destroying the spacecraft involved, but creating debris that will affect all other spacecraft using that orbit regime. In order to share the maneuver plan, a predicted ephemeris file containing the maneuver must be sent to a central authority to screen against predicted trajectories of all other on-orbit objects to determine where and when close approaches will occur that may need to be mitigated. Currently the screening authority used by US operators is the 19th Space Defense Squadron; screenings are performed once every 8 hours, meaning that spacecraft using automated maneuvering need to allow 16 hours to share their maneuver plan via the screening process in advance of maneuver execution in case one screening is missed and the next needs to be used. In an effort to speed up the screening process to benefit spacecraft using automated maneuvering, a prototype system for performing near-real-time screenings has been developed in support of the NASA Starling mission, a constellation of four cubesats that fly at the same altitude as the SpaceX Starlink constellation. Both of these constellations perform automated maneuvering, so without screening the planned maneuvers before execution, the two constellations would risk a collision. This paper describes the traditional conjunction assessment (CA) process, the prototype real-time CA screening capability, plans for the experiment to test the prototype, and next steps.

conjunction assessment↗

Automating Maneuvers: Considerations for Collision Avoidance

As more space operators implement large constellations of spacecraft, automating orbit maintenance maneuvers becomes a key feature of their operations concept to ensure that the workload is manageable. However, the practice of performing a maneuver without sharing the plan with other nearby spacecraft causes a risk that two spacecraft will collide, not only destroying the spacecraft involved, but creating debris that will affect all other spacecraft using that orbit regime. In order to share the maneuver plan, a predicted ephemeris file containing the maneuver must be sent to a central authority to screen against predicted trajectories of all other on-orbit objects to determine where and when close approaches will occur that may need to be mitigated. Currently the screening authority used by US operators is the 19th Space Defense Squadron; screenings are performed once every 8 hours, meaning that spacecraft using automated maneuvering need to allow 16 hours to share their maneuver plan via the screening process in advance of maneuver execution in case one screening is missed and the next needs to be used. In an effort to speed up the screening process to benefit spacecraft using automated maneuvering, a prototype system for performing near-real-time screenings has been developed in support of the NASA Starling mission, a constellation of four cubesats that fly at the same altitude as the SpaceX Starlink constellation. Both of these constellations perform automated maneuvering, so without screening the planned maneuvers before execution, the two constellations would risk a collision. This paper describes the traditional conjunction assessment (CA) process, the prototype real-time CA screening capability, plans for the experiment to test the prototype, and next steps.

conjunction assessment↗

Hydrogen Peroxide-Water-Ethanol-Monopropellant Blend for CubeSat Propulsion

Monopropellant propulsion that provides high performance and low hazards compared to state-of-art hydrazine are being investigated under NASA, DOD and commercially sponsored green propellant research and development programs. This NASAeffort looks at phosphate stabilized 50% hydrogen peroxide/water –ethanol blends to evaluate their stability and combustion behavior in submillimeter diameter microtube combustion apparatus for cubesat propulsion applications. Exploratory 7-day stabilitytests find no pressure rise in a sealed test tube environment at room temperature indicating at least short term stability of the mixture. Temperature rise during combustion testing in resistively heated nickel microtube apparatus shows that micro-combustion is achieved in the tube. Propellant density is approximately 1.2 g/cm3compared to 1.0 g/cm3for hydrazine. Theoretical specific impulse of the stoichiometric blend is 219 s at a chamber pressure of 20 psia and an area ratio of 30:1. Density-specific impulseof this blendis263 swhile hydrazine is only about 215-220 sin small reaction control system thrusters. This provides about 20-22% more density-specific impulse for the cubesat compared to hydrazine. The theoreticalcombustion temperature is2168°F, whichis thermally compatible with stainless steel materials of constructionand the nickel catalystused in the tests. Combustion test results are given for stoichiometric, as well as fuel-leanand fuel-richpropellant formulations. Thesetests focus on thermally and catalytically supported combustionin the microtube, whichrequires a microtube preheat temperature of about 900°F and sufficient residence time to achieve combustion that is stable and anchored in the tubewithout blowing through the tube unreacted. Thrust class is expected to be in the 10 mN range based on flow rate and estimated specific impulse.Power requirements are generally below 25 Wto heat the tube. Steady state combustion testing is typically conducted for 3 minutes and shows littledegradation of the hardware over multiple test cyclesindicating thatthere is little catalyst degradation over time and littlecatalyst deactivation due tothe phosphate stabilizer inthe hydrogen peroxide.

Monopropellant↗

Electric Sail Tether Deployment System for CubeSats

An Electric Sail (E-Sail) propulsion system consists of long, thin tethers - positively-charged wires extending radially and symmetrically outward from a spacecraft. Tethers must be biased using a high-voltage power supply to ensure that the solar wind produces thrust. While the E-Sail concept shows great promise for flying heliopause missions with higher characteristic acceleration than solar sails, there are significant technical challenges related to deploying and controlling multiple tethers. A typical full-scale design involves a hub and spoke arrangement of 10 to 100 tethers, each 20 km long. In the last 20 years, there have been multiple space mission failures due to tether deployment and control issues, and most configurations involved a single tether. This paper describes an effort to develop and test a simple yet robust single-tether deployment system for a two-6U CubeSat configuration. The project included the following: a) Tether dynamic modeling/simulation b) E-Sail single-tether prototype development and testing c) Space environmental effects testing to identify best materials for further development. These three areas of investigation were needed to provide technical rationale for an E-Sail flight demonstration mission that is expected to be proposed for the 2022 time frame. The project team used an “agile” engineering approach in which E-Sail single-tether prototype designs were iteratively developed and tested to solve problems and identify design improvements. The agile approach was ideal for this low Technology Readiness Level (TRL) project because tether deployer development involved many unknowns in prototype development that could only be discovered through iterative cycles of construction and testing. Extensive modeling and simulation were accomplished for three types of tether deployment: a) Stage 1: propulsive separation with one 6U fixed b) Stage 2: propulsive spin-up with one 6U fixed c) Stage 3: propulsive spin-up with both 6Us free Simulation results were valuable for understanding the propulsive and braking forces needed for controlled tether deployment. This paper describes the evolution, insights, and test/ performance data related to the resultant single-tether two-6U E-Sail test article which has been demonstrated in a test laboratory. The development effort suggests near-term work needed to achieve a useful flight demonstration, and provides ideas for how multiple-tether deployment systems might evolve going forward. A planned next-generation E-Sail prototype will include autonomous propulsive tether deployment while monitoring tether tension, location on the floor, distance between tether ends, acceleration, velocity, and propellant used.

Tinker, Michael↗

Recent Advances in High Altitude Pseudosatellites (HAPS) and Potential Roles in Future Earth Observing Systems

In August 2001 the NASA Environmental Research Aircraft and Sensor Technology (ERAST) Program flew the Helios aircraft to an altitude of nearly 100,000ft, demonstrating a new type of remote sensing platform. Nearly 20 years later the earth science community has unmet observational requirements to loiter over regions of interest for days or weeks as well as to follow airmasses to study chemistry and dynamics in concert with spaceborne observations. Recent advances in materials science and engineering have enabled improved battery power density, solar panel efficiency, and light yet strong structural materials required to effectively operate high-altitude (50-70k ft altitude) Pseudo-Satellites (HAPS) for 30+ days. The rapid commercialization of small unmanned aircraft has also contributed to the maturation of HAPS by making avionics, GPS, and other sub-systems smaller and less expensive. HAPS payloads provide high-resolution data that complement geostationary and polar orbiting satellites, while also enabling in-situ sampling of atmospheric chemistry and dynamics. Recent commercial interest in HAPS for 4G/5G and WIFI has funded development of a new generation of aircraft available to the science community. Here I report on a project under the NASA Airborne Science Program to test and demonstrate earth observations from a prototype aircraft being developed under a NASA Small Business Innovative Research Phase II. This aircraft will demonstrate the ability for a solar electric aircraft to deliver a 2u cubesat-based passive optical imaging satellite to 70,000ft for 30 or more days. Discussion will include the anticipated maturation timeline for HAPS, development and operational challenges, and examples of mission concepts that might contribute to future earth observing systems.

Helios aircraft↗

Deployment mechanisms for high packing efficiency One-MEter Reflectarray Antenna (OMERA)

While the capabilities of CubeSats have greatly increased in the past years, large, deployable high frequency apertures remain a limitation. The goal of this work is to develop a large 1 meter antenna operating at 35.75 GHz for RADAR applications. A reflectarray design was selected, as the flat panels are compatible with the CubeSat form factor. A center-fed, Cassegrain configuration was selected for the feed, to minimize deployed height. The flat panel configuration and Cassegrain feed allowed the entire 1 meter antenna to be compatible with a 6U bus, leaving a little under 4U of volume for remaining instrument and spacecraft components. Several iterations of the design have been built and tested, with an RF test of a fully deployed assembly being completed most recently. Prior to constructing the flight model, another iteration will need to be built and tested. The goal is to have the antenna flight ready before 2020.

Cwik, Tom↗

Deployment Mechanisms for High Packing Efficiency OneMeter Reflectarray Antenna (OMERA)

While the capabilities of CubeSats have greatly increased in the past years, large, deployable high frequency apertures remain a limitation. The goal of this work was to develop a large 1 meter antenna operating at 35.75 Ghz for RADAR applications. A reflectarray design was selected, as the flat panels were compatible with the CubeSat form factor. A center-fed, Cassegrain configuration was selected for the feed, to minimize deployed height. The flat panel configuration and Cassegrain feed allowed the entire 1 meter antenna to be compatible with a 6U bus, leaving a little under 4U of volume for remaining instrument and spacecraft components. Several iterations of the design have been built and tested, with an RF test of a fully deployed assembly being completed most recently. The goal is to have the antenna flight ready before 2020.

Cwik, Tom↗

Hydrogen Peroxide-Water-Ethanol Monopropellant Blend for CubeSat Propulsion

Monopropellant propulsion that provides high performance and low hazards compared to state-of-art hydrazine are being investigated under NASA, DOD and commercially sponsored green propellant research and development programs. This NASA effort looks at phosphate stabilized 50% hydrogen peroxide/water –ethanol blends to evaluate their stability and combustion behavior in submillimeter diameter microtube combustion apparatus for cubesat propulsion applications. Exploratory 7-day stability tests find no pressure rise in a sealed test tube environment at room temperature indicating at least short term stability of the mixture. Temperature rise during combustion testing in resistively heated nickel microtube apparatus shows that micro-combustion is achieved in the tube. Propellant density is approximately 1.2 g/cu.cm compared to 1.0 g/cu.cm for hydrazine. Theoretical specific impulse of the stoichiometric blend is 219 s at a chamber pressure of 20 psia and an area ratio of 30:1. Density-specific impulse of this blend is 263 s while hydrazine is only about 215-220 s in small reaction control system thrusters. This provides about 20-22% more density-specific impulse for the cube sat compared to hydrazine. The the oretical combustion temperature is 2168°F, which is thermally compatible with stainless steel materials of construction and the nickel catalyst used in the tests. Combustion test results are given for stoichiometric, as well as fuel-lean and fuel-rich propellant formulations. These tests focus on thermally and catalytically supported combustion in the microtube, which requires a microtube preheat temperature of about 900°F and sufficient residence time to achieve combustion that is stable and anchored in the tube without blowing through the tube unreacted. Thrust class is expected to be in the 10 m N range based on flow rate and estimated specific impulse. Power requirements are generally below 25 W to heat the tube. Steady state combustion testing is typically conducted for 3 minutes and shows little degradation of the hardware over multiple test cycles indicating that there is little catalyst degradation over time and little catalyst deactivation due to the phosphate stabilizer in the hydrogen peroxide.

Monopropellant↗

Fast Paced, Low Cost Projects at MSFC

What does an orbiting microsatellite, a robotic lander and a ruggedized camera and telescope have in common? They are all fast paced, low cost projects managed by Marshall Space Flight Center (MSFC) teamed with successful industry partners. MSFC has long been synonymous with human space flight large propulsion programs, engineering acumen and risk intolerance. However, there is a growing portfolio/product line within MSFC that focuses on these smaller, fast paced projects. While launching anything into space is expensive, using a managed risk posture, holding to schedule and keeping costs low by stopping at egood enough f were key elements to their success. Risk is defined as the possibility of loss or failure per Merriam Webster. The National Aeronautics and Space Administration (NASA) defines risk using procedural requirement 8705.4 and establishes eclasses f to discern the acceptable risk per a project. It states a Class D risk has a medium to significant risk of not achieving mission success. MSFC, along with industry partners, has created a niche in Class D efforts. How did the big, cautious MSFC succeed on these projects that embodied the antithesis of its heritage in human space flight? A key factor toward these successful projects was innovative industry partners such as Dynetics Corporation, University of Alabama in Huntsville (UAHuntsville), Johns Hopkins Applied Physics Laboratory (JHU APL), Teledyne Brown Engineering (TBE), Von Braun Center for Science and Innovation (VCSI), SAIC, and Jacobs. Fast Affordable Satellite Technology (FastSat HSV01) is a low earth orbit microsatellite that houses six instruments with the primary scientific objective of earth observation and technology demonstration. The team was comprised of Dynetics, UAHuntsvile, SAIC, Goddard Space Flight Center (GSFC) and VCSI with the United States Air Force Space Test Program as the customer. The team completed design, development, manufacturing, environmental test and integration in one year. FastSat HSV01 also deployed a Poly Picosatellite Orbital Deployer (PPOD) for a separate nano ]satellite class spacecraft (Cubesat: Nano Sail Demonstration) in partnership with Ames Research Center. The Robotic lunar lander is a MSFC JHU APL partnership that led to the development of a flexible architecture for landers to support robotic missions to a wide range of lunar and asteroid destinations. The team started with the goal of meeting NASA agency directives that led to the creation of a test bed focusing on GN&C and software to demonstrate the descent and landing on any airless body for the final 30 to 60 meters. The team created a complex technology demonstration as well as Guidance Control and Navigation (GN&C) algorithms providing autonomous control of the lander. The team uses a green propellant of 90% hydrogen peroxide and has completed 18 successful test flights. The International Space Station (ISS) SERVIR Environmental Research and Visualization System (ISERV) is a technology demonstration payload to assist the SERVIR project with environmental monitoring for disaster relief and humanitarian efforts. The ISERV project was a partnership with TBE. The ISERV payload consists of a commercial off the shelf camera, telescope, and MSFC developed power distribution box and interfaces on ISS with the Window Observational Research Facility in the US Lab. MSFC has identified three key areas that enabled the low cost mission success to include culture, partnering, and cost/schedule control. This paper will briefly discuss these three Class D efforts, FastSat HSV-01, the Robotic Lunar Lander and the ISERV camera system, the lessons learned, their successes and challenges.

Watson-Morgan, Lisa↗