SEARCH · Search NASA

Results for “formation flying spacecraft”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20

All sources NASA NTRS DOE OSTI

NASA NTRS2013

Sequential Probability Ratio Test for Spacecraft Collision Avoidance Maneuver Decisions

A document discusses sequential probability ratio tests that explicitly allow decision-makers to incorporate false alarm and missed detection risks, and are potentially less sensitive to modeling errors than a procedure that relies solely on a probability of collision threshold. Recent work on constrained Kalman filtering has suggested an approach to formulating such a test for collision avoidance maneuver decisions: a filter bank with two norm-inequality-constrained epoch-state extended Kalman filters. One filter models the null hypotheses that the miss distance is inside the combined hard body radius at the predicted time of closest approach, and one filter models the alternative hypothesis. The epoch-state filter developed for this method explicitly accounts for any process noise present in the system. The method appears to work well using a realistic example based on an upcoming, highly elliptical orbit formation flying mission.

Carpenter, J. Russell↗

NASA NTRS2014

Magnetospheric Multiscale Science Mission Profile and Operations

The Magnetospheric Multiscale (MMS) mission and operations are designed to provide the maximum reconnection science. The mission phases are chosen to investigate reconnection at the dayside magnetopause and in the magnetotail. At the dayside, the MMS orbits are chosen to maximize encounters with the magnetopause in regions where the probability of encountering the reconnection diffusion region is high. In the magnetotail, the orbits are chosen to maximize encounters with the neutral sheet, where reconnection is known to occur episodically. Although this targeting is limited by engineering constraints such as total available fuel, high science return orbits exist for launch dates over most of the year. The tetrahedral spacecraft formation has variable spacing to determine the optimum separations for the reconnection regions at the magnetopause and in the magnetotail. In the specific science regions of interest, the spacecraft are operated in a fast survey mode with continuous acquisition of burst mode data. Later, burst mode triggers and a ground-based scientist in the loop are used to determine the highest quality data to downlink for analysis. This operations scheme maximizes the science return for the mission.

Mission Design↗

NASA NTRS2012

Navigation of the Twin GRAIL Spacecraft into Science Formation at the Moon

On February 29, 2012 the twin NASA Gravity Recovery And Interior Laboratory (GRAIL) spacecraft, Ebb and flow, achieved precise synchronized formation for collecting highly sensitive lunar gravity data. This was accomplished after performing a total of 27 propulsive maneuvers between the two spacecraft (13 on Ebb, 14 on Flow) over six months. Each 300 kg GRAIL spacecraft independently flew a 3.8-month, low-energy trajectory to reach the Moon after separation from the launch vehicle on September 10, 2011. The space craft were captured into 11.5 hr co- planar polar orbits after performing Lunar Orbit Insertion (LOI) maneuvers on New Years Eve (Dec 31, 2011) and New Years Day (Jan 1, 2012), respectively for Ebb, and Flow. Once captured, each spacecraft performed clusters of period reduction maneuvers to bring their orbit periods down to just less than 2 hrs. Finally, the orbiters we replaced into science formation by performing five strategic maneuvers (2 on Ebb, 3 on Flow). These maneuvers ensured 3 months of orbit life time with mean altitudes of 55 km and separations of 82-217 km by targeting the orbits' eccentricity vectors to specific locations. This paper will discuss the navigation strategy and performance of the twin GRAIL spacecraft from the September 10, 2011 launch through the end of the Prime Mission Science Phase in June 2012.

lunar gravity↗

NASA NTRS1994

Reaction and Protection of Electrical Wire Insulators in Atomic-oxygen Environments

Atomic-oxygen erosion on spacecraft in low Earth orbit is an issue which is becoming increasingly important because of the growing number of spacecraft that will fly in the orbits which have high concentrations of atomic oxygen. In this investigation, the atomic-oxygen durability of three types of electrical wire insulation (carbon-based, fluoropolymer, and polysiloxane elastomer) were evaluated. These insulation materials were exposed to thermal-energy atomic oxygen, which was obtained by RF excitation of air at a pressure of 11-20 Pa. The effects of atomic-oxygen exposure on insulation materials indicate that all carbon-based materials erode at about the same rate as polyamide Kapton and, therefore, are not atomic-oxygen durable. However, the durability of fluoropolymers needs to be evaluated on a case by case basis because the erosion rates of fluoropolymers vary widely. For example, experimental data suggest the formation of atomic fluorine during atomic-oxygen amorphous-fluorocarbon reactions. Dimethyl polysiloxanes (silicone) do not lose mass during atomic-oxygen exposure, but develop silica surfaces which are under tension and frequently crack as a result of loss of methyl groups. However, if the silicone sample surfaces were properly pretreated to provide a certain roughness, atomic oxygen exposure resulted in a sturdy, non-cracked atomic-oxygen durable SiO2 layer. Since the surface does not crack during such silicone-atomic oxygen reaction, the crack-induced contamination by silicone can be reduced or completely stopped. Therefore, with proper pretreatment, silicone can be either a wire insulation material or a coating on wire insulation materials to provide atomic-oxygen durability.

Hung, Ching-Cheh↗

NASA NTRS2000

Semi-Major Axis Knowledge and GPS Orbit Determination

In recent years spacecraft designers have increasingly sought to use onboard Global Positioning System receivers for orbit determination. The superb positioning accuracy of GPS has tended to focus more attention on the system's capability to determine the spacecraft's location at a particular epoch than on accurate orbit determination, per se. The determination of orbit plane orientation and orbit shape to acceptable levels is less challenging than the determination of orbital period or semi-major axis. It is necessary to address semi-major axis mission requirements and the GPS receiver capability for orbital maneuver targeting and other operations that require trajectory prediction. Failure to determine semi-major axis accurately can result in a solution that may not be usable for targeting the execution of orbit adjustment and rendezvous maneuvers. Simple formulas, charts, and rules of thumb relating position, velocity, and semi-major axis are useful in design and analysis of GPS receivers for near circular orbit operations, including rendezvous and formation flying missions. Space Shuttle flights of a number of different GPS receivers, including a mix of unfiltered and filtered solution data and Standard and Precise Positioning Service modes, have been accomplished. These results indicate that semi-major axis is often not determined very accurately, due to a poor velocity solution and a lack of proper filtering to provide good radial and speed error correlation.

Carpenter, J. Russell↗

NASA NTRS2000

Semi-Major Axis Knowledge and GPS Orbit Determination

In recent years spacecraft designers have increasingly sought to use onboard Global Positioning System receivers for orbit determination. The superb positioning accuracy of GPS has tended to focus more attention on the system's capability to determine the spacecraft's location at a particular epoch than on accurate orbit determination, per se. The determination of orbit plane orientation and orbit shape to acceptable levels is less challenging than the determination of orbital period or semi-major axis. It is necessary to address semi-major axis mission requirements and the GPS receiver capability for orbital maneuver targeting and other operations that require trajectory prediction. Failure to determine semi-major axis accurately can result in a solution that may not be usable for targeting the execution of orbit adjustment and rendezvous maneuvers. Simple formulas, charts, and rules of thumb relating position, velocity, and semi-major axis are useful in design and analysis of GPS receivers for near circular orbit operations, including rendezvous and formation flying missions. Space Shuttle flights of a number of different GPS receivers, including a mix of unfiltered and filtered solution data and Standard and Precise Positioning, Service modes, have been accomplished. These results indicate that semi-major axis is often not determined very accurately, due to a poor velocity solution and a lack of proper filtering to provide good radial and speed error correlation.

Carpenter, J. Russell↗

NASA NTRS2018

Oceanus: A High Science Return Uranus Orbiter with a Low-Cost Instrument Suite

Ice-giant-sized planets are the most common type of observed exoplanet, yet the two ice giants in our own solar system (Uranus and Neptune) are the least explored class of planet, having only been observed through ground-based observations and a single flyby each by Voyager 2 approximately 30 years ago. These single flybys were unable to characterize the spatial and temporal variability in ice giant magnetospheres, some of the most odd and intriguing magnetospheres in the solar system. They also offered only limited constraints on the internal structure of ice giants; understanding the internal structure of a planet is important for understanding its formation and evolution. The most recent planetary science Decadal Survey by the U.S. National Academy of Sciences, ''Vision and Voyages for Planetary Science in the Decade 2013-2022,'' identified the ice giant Uranus as the third highest priority for a Flagship mission in the decade 2013-2022. However, in the event that NASA or another space agency is unable to fly a Flagship-class mission to an ice giant in the next decade, this paper presents a mission concept for a focused, lower cost Uranus orbiter called OCEANUS (Origins and Composition of the Exoplanet Analog Uranus System). OCEANUS would increase our understanding of the interior structure of Uranus, its magnetosphere, and how its magnetic field is generated. These goals could be achieved with just a magnetometer and the spacecraft's radio system. This study shows that several of the objectives outlined by the Decadal Survey, including one of the two identified as highest priority, are within reach for a New-Frontiers-class mission.

Elder, C. M.↗

NASA NTRS2006

Non Radiation Hardened Microprocessors in Spaced Based Remote Sensing Systems

The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission is a comprehensive suite of active and passive sensors including a 20Hz 230mj Nd:YAG lidar, a visible wavelength Earth-looking camera and an imaging infrared radiometer. CALIPSO flies in formation with the Earth Observing System Post-Meridian (EOS PM) train, provides continuous, near-simultaneous measurements and is a planned 3 year mission. CALIPSO was launched into a 98 degree sun synchronous Earth orbit in April of 2006 to study clouds and aerosols and acquires over 5 gigabytes of data every 24 hours. The ground track of one CALIPSO orbit as well as high and low intensity South Atlantic Anomaly outlines is shown. CALIPSO passes through the SAA several times each day. Spaced based remote sensing systems that include multiple instruments and/or instruments such as lidar generate large volumes of data and require robust real-time hardware and software mechanisms and high throughput processors. Due to onboard storage restrictions and telemetry downlink limitations these systems must pre-process and reduce the data before sending it to the ground. This onboard processing and realtime requirement load may mean that newer more powerful processors are needed even though acceptable radiation-hardened versions have not yet been released. CALIPSO's single board computer payload controller processor is actually a set of four (4) voting non-radiation hardened COTS Power PC 603r's built on a single width VME card by General Dynamics Advanced Information Systems (GDAIS). Significant radiation concerns for CALIPSO and other Low Earth Orbit (LEO) satellites include the South Atlantic Anomaly (SAA), the north and south poles and strong solar events. Over much of South America and extending into the South Atlantic Ocean the Van Allen radiation belts dip to just 200-800km and spacecraft entering this area are subjected to high energy protons and experience higher than normal Single Event Upset (SEU) and Single Event Latch-up (SEL) rates. Although less significant, spacecraft flying in the area around the poles experience similar upsets. Finally, powerful solar proton events in the range of 10MeV/10pfu to 100MeV/1pfu as are forecasted and tracked by NOAA's Space Environment Center in Colorado can result in Single Event Upset (SEU), Single Event Latch-up (SEL) and permanent failures such as Single Event Gate Rupture (SEGR) in some technologies. (Galactic Cosmic Rays (GCRs) are another source, especially for gate rupture) CALIPSO mitigates common radiation concerns in its data handling through the use of redundant processors, radiation-hardened Application Specific Integrated Circuits (ASIC), hardware-based Error Detection and Correction (EDAC), processor and memory scrubbing, redundant boot code and mirrored files. After presenting a system overview this paper will expand on each of these strategies. Where applicable, related on-orbit data collected since the CALIPSO initial boot on May 4, 2006 will be noted.

Decoursey, Robert J.↗

NASA NTRS2006

NASA Tech Briefs, September 2006

Topics covered include: Improving Thermomechanical Properties of SiC/SiC Composites; Aerogel/Particle Composites for Thermoelectric Devices; Patches for Repairing Ceramics and Ceramic- Matrix Composites; Lower-Conductivity Ceramic Materials for Thermal-Barrier Coatings; An Alternative for Emergency Preemption of Traffic Lights; Vehicle Transponder for Preemption of Traffic Lights; Automated Announcements of Approaching Emergency Vehicles; Intersection Monitor for Traffic-Light-Preemption System; Full-Duplex Digital Communication on a Single Laser Beam; Stabilizing Microwave Frequency of a Photonic Oscillator; Microwave Oscillators Based on Nonlinear WGM Resonators; Pointing Reference Scheme for Free-Space Optical Communications Systems; High-Level Performance Modeling of SAR Systems; Spectral Analysis Tool 6.2 for Windows; Multi-Platform Avionics Simulator; Silicon-Based Optical Modulator with Ferroelectric Layer; Multiplexing Transducers Based on Tunnel-Diode Oscillators; Scheduling with Automated Resolution of Conflicts; Symbolic Constraint Maintenance Grid; Discerning Trends in Performance Across Multiple Events; Magnetic Field Solver; Computing for Aiming a Spaceborne Bistatic- Radar Transmitter; 4-Vinyl-1,3-Dioxolane-2-One as an Additive for Li-Ion Cells; Probabilistic Prediction of Lifetimes of Ceramic Parts; STRANAL-PMC Version 2.0; Micromechanics and Piezo Enhancements of HyperSizer; Single-Phase Rare-Earth Oxide/Aluminum Oxide Glasses; Tilt/Tip/Piston Manipulator with Base-Mounted Actuators; Measurement of Model Noise in a Hard-Wall Wind Tunnel; Loci-STREAM Version 0.9; The Synergistic Engineering Environment; Reconfigurable Software for Controlling Formation Flying; More About the Tetrahedral Unstructured Software System; Computing Flows Using Chimera and Unstructured Grids; Avoiding Obstructions in Aiming a High-Gain Antenna; Analyzing Aeroelastic Stability of a Tilt-Rotor Aircraft; Tracking Positions and Attitudes of Mars Rovers; Stochastic Evolutionary Algorithms for Planning Robot Paths; Compressible Flow Toolbox; Rapid Aeroelastic Analysis of Blade Flutter in Turbomachines; General Flow-Solver Code for Turbomachinery Applications; Code for Multiblock CFD and Heat-Transfer Computations; Rotating-Pump Design Code; Covering a Crucible with Metal Containing Channels; Repairing Fractured Bones by Use of Bioabsorbable Composites; Kalman Filter for Calibrating a Telescope Focal Plane; Electronic Absolute Cartesian Autocollimator; Fiber-Optic Gratings for Lidar Measurements of Water Vapor; Simulating Responses of Gravitational-Wave Instrumentation; SOFTC: A Software Correlator for VLBI; Progress in Computational Simulation of Earthquakes; Database of Properties of Meteors; Computing Spacecraft Solar-Cell Damage by Charged Particles; Thermal Model of a Current-Carrying Wire in a Vacuum; Program for Analyzing Flows in a Complex Network; Program Predicts Performance of Optical Parametric Oscillators; Processing TES Level-1B Data; Automated Camera Calibration; Tracking the Martian CO2 Polar Ice Caps in Infrared Images; Processing TES Level-2 Data; SmaggIce Version 1.8; Solving the Swath Segment Selection Problem; The Spatial Standard Observer; Less-Complex Method of Classifying MPSK; Improvement in Recursive Hierarchical Segmentation of Data; Using Heaps in Recursive Hierarchical Segmentation of Data; Tool for Statistical Analysis and Display of Landing Sites; Automated Assignment of Proposals to Reviewers; Array-Pattern-Match Compiler for Opportunistic Data Analysis; Pre-Processor for Compression of Multispectral Image Data; Compressing Image Data While Limiting the Effects of Data Losses; Flight Operations Analysis Tool; Improvement in Visual Target Tracking for a Mobile Robot; Software for Simulating Air Traffic; Automated Vectorization of Decision-Based Algorithms; Grayscale Optical Correlator Workbench; "One-Stop Shopping" for Ocean Remote-Sensing and Model Data; State Analysis Database Tool; Generating CAHV and CAHVOmages with Shadows in ROAMS; Improving UDP/IP Transmission Without Increasing Congestion; FORTRAN Versions of Reformulated HFGMC Codes; Program for Editing Spacecraft Command Sequences; Flight-Tested Prototype of BEAM Software; Mission Scenario Development Workbench; Marsviewer; Tool for Analysis and Reduction of Scientific Data; ASPEN Version 3.0; Secure Display of Space-Exploration Images; Digital Front End for Wide-Band VLBI Science Receiver; Multifunctional Tanks for Spacecraft; Lightweight, Segmented, Mostly Silicon Telescope Mirror; Assistant for Analyzing Tropical-Rain-Mapping Radar Data; and Anion-Intercalating Cathodes for High-Energy- Density Cells.

Source record↗

NASA NTRSDate not supplied

DiskSat: Demonstration Mission for a Two-Dimensional Satellite Architecture

The DiskSat is a quasi-two-dimensional satellite bus architecture designed for applications requiring high power, large apertures, and/or high maneuverability in a low-mass satellite. A representative DiskSat structure is a composite flat panel, one meter in diameter and 2.5 cm thick. The volume is almost 20 liters, equivalent to a hypothetical 20U CubeSat, while the structural mass is less than 3 kg. The surface area is large enough to host over 200 W of solar cells without deployable solar panels. For launch, multiple DiskSats are stacked in a fully enclosed container/deployer using a simple mechanical interface and are released individually in orbit. The Aerospace Corporation, with the support of the NASA Space Technology Mission Directorate (STMD), is preparing a flight of four DiskSats for launch in 2024 to demonstrate the feasibility of both the dispenser and the DiskSat bus. In addition, the flight is expected to demonstrate several features of the DiskSat including the unprecedented high power-to-mass ratio, the maneuverability of the bus using low-thrust electric propulsion, and the ability to fly continuously in a low-drag orientation, enabling operations in very low Earth orbits (VLEO). The DiskSats will be launched in and deployed from a dispenser that provides a containerized rideshare environment; the dispenser fully encloses the DiskSats during launch and then opens to dispense the satellites one at a time once in orbit. The dispenser is modular in design and expandable from the capacity of four DiskSats for this flight to as many as 20 DiskSats for future flights. NASA STMD seeks disruptive and innovative technologies that could help lead to the next-generation systems for future science and exploration missions. DiskSat is a potentially disruptive technology leading to new, enabling architectures using ever-more capable small spacecraft. Data generated from this flight will inform the drafting of a DiskSat standard intended to encourage easy and frequent access to space, in the same manner as the CubeSat standard. DiskSat is expected to become a standard format for rideshare-compatible, high-power, maneuverable, low-mass satellites for Earth-orbit, cis-lunar, and deep space applications.

Richard Welle↗

NASA NTRS2008

Flight-Like Ground Demonstrations of Precision Maneuvers for Spacecraft Formations

Synchronized formation rotations are a common maneuver for planned precision formations. In such a rotation, attitudes remain synchronized with relative positions, as if the spacecraft were embedded in a virtual rigid body. Further, since synchronized rotations are needed for science data collection, this maneuver requires the highest precision control of formation positions and attitudes. A recently completed, major technology milestone for the Terrestrial Planet Finder Interferometer is the high-fidelity, ground demonstration of precision synchronized formation rotations. These demonstrations were performed in the Formation Control Testbed (FCT), which is a flight-like, multi-robot formation testbed. The FCT is briefly introduced, and then the synchronized rotation demonstration results are presented. An initial error budget consisting of formation simulations is used to show the connection between ground performance and TPF-I flight performance.

formation flying↗

NASA NTRS2002

Optical metrology for Starlight Separated Spacecraft Stellar Interferometry Mission

We describe a high-precision inter-spacecraft metrology system designed for NASA 's StarLight mission, a space-based separated-spacecraft stellar interferometer. It consists of dual-target linear metrology, based on a heterodyne interferometer with carrier phase modulation, and angular metrology designed to sense the pointing of the laser beam and provides bearing information. The dual-target operation enables one metrology beam to sense displacement of two targets independently. We present the current design, breadboard implementation of the Metrology Subsystem in a stellar interferometer testbed and the present state of development of flight qualifiable subsystem components.

metrology stellar interferometry formation flying↗

NASA NTRS2004

L2 Earth Atmosphere Observatory: Formation Guidance, Metrology and Control Synthesis

The Earth Observatory Formation at L2, a Lagrange libration point, is a unique large aperture (25 m diameter) space telescope concept that will improve the knowledge and understanding of dynamic, chemical and radiative mechanisms that cause changes in the atmosphere, and can lead to the development of models and techniques to predict short and long-term climate changes. The results of this concept definition study show that the telescope concept is feasible, and can have technology readiness in the 2020 time frame. Further advanced development in several subsystems is needed, such as higher efficiency Xenon ion thrusters with throttling, and optical quality large membrane mirror with active shape control. It presents an analysis and solution of guidance, sensing, control, and propulsion problems for a formation of two spacecraft on the Sun-Earth line in the neighborhood of the Sun-Earth L2 point, that observes Earth s atmosphere during continuous solar occultation by the Earth. A system architecture is described for the observatory, and its components that include unique mission specific metrology. The formation must follow a powered trajectory with strictly limited fuel use to observe solar occultation. A configuration of ion thrusters and reaction wheels for translation and attitude control is designed along with algorithms for orbit following and formation control. Simulation results of the orbital and formation dynamics are presented that verify performance of the control systems.

Earth Atmosphere Observatory Formation↗

NASA NTRS2004

NASA Tech Briefs, July 2004

Topics: Optoelectronic Sensor System for Guidance in Docking; Hybrid Piezoelectric/Fiber-Optic Sensor Sheets; Multisensor Arrays for Greater Reliability and Accuracy; Integrated-Optic Oxygen Sensors; Ka-Band Autonomous Formation Flying Sensor; CMOS VLSI Active-Pixel Sensor for Tracking; Lightweight, Self-Deploying Foam Antenna Structures; Electrically Small Microstrip Quarter-Wave Monopole Antennas; A 2-to-28-MHz Phase-Locked Loop; Portable Electromyograph; Open-Source Software for Modeling of Nanoelectronic Devices; Software for Generating Strip Maps from SAR Data; Calibration Software for use with Jurassicprok; Software for Probabilistic Risk Reduction; Software Processes SAR Motion-Measurement Data; Improved Method of Purifying Carbon Nanotubes; Patterned Growth of Carbon Nanotubes or Nanofibers; Lightweight, Rack-Mountable Composite Cold Plate/Shelves; SiC-Based Miniature High-Temperature Cantilever Anemometer; Inlet Housing for a Partial-Admission Turbine; Lightweight Thermoformed Structural Components and Optics; Growing High-Quality InAs Quantum Dots for Infrared Lasers; Selected Papers on Protoplanetary Disks; Module for Oxygenating Water without Generating Bubbles; Coastal Research Imaging Spectrometer; Rapid Switching and Modulation by use of Coupled VCSELs; Laser-Induced-Fluorescence Photogrammetry and Videogrammetry; Laboratory Apparatus Generates Dual-Species Cold Atomic Beam; Laser Ablation of Materials for Propulsion of Spacecraft; Small Active Radiation Monitor; Hybrid Image-Plane/Stereo Manipulation; Partitioning a Gridded Rectangle into Smaller Rectangles; Digital Radar-Signal Processors Implemented in FPGAs; Part 1 of a Computational Study of a Drop-Laden Mixing Layer; and Some Improvements in Signal-Conditioning Circuits.

Source record↗

NASA NTRS2004

Dynamics of Earth orbiting formations

In this paper the equations of motion of a formation consisting of n spacecraft in Earth orbit are derived via Lagrange's equations. The equations of motion of the formation are developed with respect to both (1) a bound Keplerian reference orbit, and (2) a specific spacecraft in the formation. The major orbital perturbations acting on a formation in low Earth orbit are also included in the analysis. In contrast to the traditional approach based on the balance of linear momentum, the use of Lagrange's equations leads to a high-level matrix derivation of the formation equations of motion. The matrix form of the nonlinear motion equations is then linearized about a bound Keplerian reference orbit. Next, it is demonstrated that under the assumption of a circular reference orbit, the linearized equations of motion reduce to the well-known Hill-Clohessy-Wiltshire equations. The resulting linear and nonlinear dynamic equations lead to maximal physical insight into the structure of formation dynamics, and are ideally suited for use in the design and validation of formation guidance and control laws.

formation flying↗

NASA NTRS1981

Pioneer fly-by of Saturn and its rings

Results acquired by the imaging photopolarimeter on board Pioneer 11 during the spacecraft fly-by of Saturn and its rings on September 1, 1979 are reviewed. Analysis of the broadband photometry and polarimetry obtained of the Saturn atmosphere has been used to determine a cloud top height of 300 mb and a scale height of the aerosol distribution about 1/4 that of the ambient gas, and to point out differences between the forward scattering and belt and zone characteristics of the Saturn and Jupiter atmospheres. Images of Saturn's rings have been used to derive a profile of ring optical depth between 1.22 and 2.35 Saturn radii, and reveal new divisions and thin rings and azimuthal variations in the brightness of the A ring not observable from earth. Linear polarization observations of Titan in red and blue light reveal that the aerosols near the top of the atmosphere have radii less than about 0.09 micron and that the optical thickness of the small aerosol layer is about 0.6 above an effectively depolarizing surface, and indicate radii of 2845 + or - 25 km and 2880 + or - 22 km in red and blue light, respectively. Earth-based and spacecraft data are consistent with the formation of rings structures as a result of Poynting-Robertson drag and gravitational satellite resonances with the original ice and rock particles.

Gehrels, T.↗

NASA NTRS2015

CloudSat Anomaly and Return to the A-Train: Lessons Learned for Satellite Constellations

In April 2011, CloudSat suffered a severe battery anomaly, leaving the space-craft in emergency mode without the ability to command or maneuver the spacecraft. Before the team was able to recover spacecraft operability, CloudSat passed close to the Aqua satellite in the A-Train and then exited the A-Train. A new mode of operations, termed Daylight Only Operations (DO-Op) mode was developed to enable CloudSat to resume science operations in an orbit under the A-Train by November 2011, and in July 2012 CloudSat re-entered the A-Train. This paper describes challenges and lessons-learned during the anomaly, the exit from the A-Train and the return to the A-Train. These lessons-learned may ap-ply to other current and future satellite constellations in Earth orbit.

formation-flying↗

NASA NTRS2018

Technology Development in Support of Hyperspectral Infrared Atmospheric Sounding in a CubeSat

Hyperspectral infrared sounding in a CubeSat will provide a new dimension to the current suite of IR sounders by allowing measurements at multiple times of day and enabling formation flying of IR sounders for new data products such as Atmospheric Motion Vector (AMV) winds. This paper focuses on technology development during the CubeSat Infrared Atmospheric Sounder (CIRAS) project sponsored by the NASA Earth Science Technology Office (ESTO), and coincident studies by the NOAA Office of Projects, Planning, and Analysis (OPPA). The CIRAS approach incorporates key new instrument technologies developed at JPL’s Microdevices Lab (MDL) including a 2D array of High Operating Temperature Barrier Infrared Detector (HOT-BIRD) material, selected for its high uniformity, low cost, low noise and higher operating temperatures than traditional materials. The second key technology is an MWIR Grating Spectrometer (MGS) designed by Ball Aerospace with a JPL MDL slit and immersion grating to provide hyperspectral infrared imaging in a CubeSat volume. The third key technology is a blackbody calibration target fabricated with MDL’s black silicon to have very high emissivity in a flat plate construction. JPL has completed design and breadboard of the mechanical, electronic and thermal subsystems for CIRAS payload including a HOT-BIRD FPA, with filters in a dewar and a breadboard of the electronics and scan mirror assembly. Blue Canyon Technologies, developer of the CIRAS 6U CubeSat, completed the Final Design Review for the spacecraft.

Yee, Karl↗