Lockheed Martin (Australia)

The Atmospheric Imaging Assembly (AIA) provides multiple simultaneous high-resolution full-disk images of the corona and transition region up to 0.5 R ⊙ above the solar limb with 1.5-arcsec spatial resolution and 12-second temporal resolution. The AIA consists of four telescopes that employ normal-incidence, multilayer-coated optics to provide narrow-band imaging of seven extreme ultraviolet (EUV) band passes centered on specific lines: Fe xviii (94 Å), Fe viii, xxi (131 Å), Fe ix (171 Å), Fe xii, xxiv (193 Å), Fe xiv (211 Å), He ii (304 Å), and Fe xvi (335 Å). One telescope observes C iv (near 1600 Å) and the nearby continuum (1700 Å) and has a filter that observes in the visible to enable coalignment with images from other telescopes. The temperature diagnostics of the EUV emissions cover the range from 6×104 K to 2×107 K. The AIA was launched as a part of NASA’s Solar Dynamics Observatory (SDO) mission on 11 February 2010. AIA will advance our understanding of the mechanisms of solar variability and of how the Sun’s energy is stored and released into the heliosphere and geospace.

The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) is an array of four normal-incidence reflecting telescopes that image the Sun in ten EUV and UV wavelength channels. We present the initial photometric calibration of AIA, based on preflight measurements of the response of the telescope components. The estimated accuracy is of order 25%, which is consistent with the results of comparisons with full-disk irradiance measurements and spectral models. We also describe the characterization of the instrument performance, including image resolution, alignment, camera-system gain, flat-fielding, and data compression.

The Interstellar Boundary Explorer (IBEX) is a small explorer mission that launched on 19 October 2008 with the sole, focused science objective to discover the global interaction between the solar wind and the interstellar medium. IBEX is designed to achieve this objective by answering four fundamental science questions: (1) What is the global strength and structure of the termination shock, (2) How are energetic protons accelerated at the termination shock, (3) What are the global properties of the solar wind flow beyond the termination shock and in the heliotail, and (4) How does the interstellar flow interact with the heliosphere beyond the heliopause? The answers to these questions rely on energy-resolved images of energetic neutral atoms (ENAs), which originate beyond the termination shock, in the inner heliosheath. To make these exploratory ENA observations IBEX carries two ultra-high sensitivity ENA cameras on a simple spinning spacecraft. IBEX’s very high apogee Earth orbit was achieved using a new and significantly enhanced method for launching small satellites; this orbit allows viewing of the outer heliosphere from beyond the Earth’s relatively bright magnetospheric ENA emissions. The combination of full-sky imaging and energy spectral measurements of ENAs over the range from ∼10 eV to 6 keV provides the critical information to allow us to achieve our science objective and understand this global interaction for the first time. The IBEX mission was developed to provide the first global views of the Sun’s interstellar boundaries, unveiling the physics of the heliosphere’s interstellar interaction, providing a deeper understanding of the heliosphere and thereby astrospheres throughout the galaxy, and creating the opportunity to make even greater unanticipated discoveries.

International audience

The immense volume of data generated by the suite of instruments on the Solar Dynamics Observatory (SDO) requires new tools for efficient identifying and accessing data that is most relevant for research. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.

In Fall 2008 NASA selected a large international consortium to produce a comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of the Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field images from the Helioseismic and Magnetic Imager (HMI). We produce robust, very efficient, professionally coded software modules that can keep up with the SDO data stream and detect, trace, and analyze numerous phenomena, including flares, sigmoids, filaments, coronal dimmings, polarity inversion lines, sunspots, X-ray bright points, active regions, coronal holes, EIT waves, coronal mass ejections (CMEs), coronal oscillations, and jets. We also track the emergence and evolution of magnetic elements down to the smallest detectable features and will provide at least four full-disk, nonlinear, force-free magnetic field extrapolations per day. The detection of CMEs and filaments is accomplished with Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO) and ground-based Hα data, respectively. A completely new software element is a trainable feature-detection module based on a generalized image-classification algorithm. Such a trainable module can be used to find features that have not yet been discovered (as, for example, sigmoids were in the pre-Yohkoh era). Our codes will produce entries in the Heliophysics Events Knowledgebase (HEK) as well as produce complete catalogs for results that are too numerous for inclusion in the HEK, such as the X-ray bright-point metadata. This will permit users to locate data on individual events as well as carry out statistical studies on large numbers of events, using the interface provided by the Virtual Solar Observatory. The operations concept for our computer vision system is that the data will be analyzed in near real time as soon as they arrive at the SDO Joint Science Operations Center and have undergone basic processing. This will allow the system to produce timely space-weather alerts and to guide the selection and production of quicklook images and movies, in addition to its prime mission of enabling solar science. We briefly describe the complex and unique data-processing pipeline, consisting of the hardware and control software required to handle the SDO data stream and accommodate the computer-vision modules, which has been set up at the Lockheed-Martin Space Astrophysics Laboratory (LMSAL), with an identical copy at the Smithsonian Astrophysical Observatory (SAO).

In order for a virtual environment to be effective as a training tool, it is not enough to concentrate on the fidelity of the renderings and the accuracy of the simulated behaviors. The environment should help trainees develop an understanding of the task and should provide guidance and assistance as needed. This paper describes a system for developing virtual environments in which pedagogical capabilities are incorporated into autonomous agents that interact with trainees and simulations of objects in the environment. These pedagogical agents can monitor trainee progress and provide guidance and assistance. This paper describes the architectural features of the environment and of the agents that accomplish the instructional objectives within the virtual environment. It also discusses how agent-based instruction is combined with other methods of delivering instruction.

Observations obtained at the Swedish Solar Observatory, La Palma, using the Lockheed tunable lter, have been used to measure properties of active region faculae, including contrast from disk center to near the limb. The data consist of coregistered digital photometric images of the line-of-sight magnetic eld and of the continuum intensity.

We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light, image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described.

The three-dimensional (3D) modeling of coronal loops and filaments requires algorithms that automatically trace curvilinear features in solar EUV or soft X-ray images. We compare five existing algorithms that have been developed and customized to trace curvilinear features in solar images: i) the oriented-connectivity method (OCM), which is an extension of the Strous pixel-labeling algorithm (developed by Lee, Newman, and Gary); ii) the dynamic aperture-based loop-segmentation method (developed by Lee, Newman, and Gary); iii) unbiased detection of curvilinear structures (developed by Steger, Raghupathy, and Smith); iv) the oriented-direction method (developed by Aschwanden); and v) ridge detection by automated scaling (developed by Inhester). We test the five existing numerical codes with a TRACE image that shows a bipolar active region and contains over 100 discernable loops. We evaluate the performance of the five codes by comparing the cumulative distribution of loop lengths, the median and maximum loop length, the completeness or detection efficiency, the accuracy, and flux sensitivity. These algorithms are useful for the reconstruction of the 3D geometry of coronal loops from stereoscopic observations with the STEREO spacecraft, or for quantitative comparisons of observed EUV loop geometries with (nonlinear force-free) magnetic field extrapolation models.

Heliophysics is a developing scientific discipline integrating studies of the Sun's variability, the surrounding heliosphere, and climatic environments. Over the past few centuries, our understanding of how the Sun drives space weather and climate on the Earth and other planets has advanced at an ever-increasing rate. This volume, the first in this series of three heliophysics texts, integrates such diverse topics for the first time as a coherent intellectual discipline. It emphasises the physical processes coupling the Sun and Earth, allowing insights into the interaction of the solar wind and radiation with the Earth's magnetic field, atmosphere and climate system. It provides a core resource for advanced undergraduates and graduates, and also constitutes a foundational reference for researchers in heliophysics, astrophysics, plasma physics, space physics, solar physics, aeronomy, space weather, planetary science and climate science. Additional online resources, including lecture presentations and other teaching materials, are accessible at www.cambridge.org/9780521110617.

A generally applicable and computationally efficient description of random irradiance fluctuations induced by single scattering from distributed low-order turbulence (LOT) phase fluctuations is developed for Gaussian beams in the weak scintillation regime. The LOT solution describes irradiance statistics resulting from coarse beam irradiance fluctuations such as beam wander and beam breathing and will generally underestimate the true scintillation owing to the neglect of higher orders. For a subset of beam and turbulence settings that naturally result in non-log-normal irradiance behavior in the weak regime, the LOT solution closely approaches the exact solution and accurately describes the irradiance statistics for any point on the observation plane. For the same settings, beam-wave scintillation theory derived from the Rytov perturbation method yields inaccurate predictions owing to an inherent confinement to log-normal behavior. Examples that naturally exhibit non-log-normal irradiance behavior include focused beams on horizontal paths and collimated beams on ground-to-space paths. The complementary nature of the two scintillation theories (LOT and Rytov) enables a hybrid combination that yields accurate and convenient scintillation predictions for any case exhibiting weak scintillation regardless of irradiance behavior. Comparison of hybrid model predictions with wave optics simulation data reveals excellent agreement.

We introduce an iterative procedure for design of adaptive <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">KL</i> -variate linear beamformers that are structured as the Kronecker product of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> -variate (transmit) and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> -variate (receive) beamformers. We focus on MIMO radar applications for scenarios where only joint transmit and receive adaptive beamforming can efficiently mitigate multi-mode propagated backscatter interference. This is because the direction-of-departure (DoD) on one interference mode, and the direction-of-arrival (DoA) on the other, coincide with those of a target, respectively. We introduce a Markov model for the adaptive iterative routine, specify its convergence condition, and derive final (stable) signal-to-interference-plus-noise ratio (SINR) performance characteristics. Simulation results demonstrate high accuracy of the analytical derivations. In addition, we demonstrate, that for the considered class of multiple-input multiple-output (MIMO) radar interference scenarios, the diagonally loaded sample matrix inversion (SMI) algorithm provides additional performance improvement and convergence rate for this iterative adaptive Kronecker beamformer.

In over-the-horizon radar (OTHR) the need to preferentially select propagation mode arises when one or more modes are perturbed by ionospheric disturbances. Due to mixed-mode propagation and range-elevation coupling, such control is only implementable using noncausal beamforming via MIMO radar architectures. We introduce three key principles that govern mode-selective multiple-input multiple-output (MIMO) OTHR design. Numerical examples illustrate the high potential efficiency of mode-selective MIMO OTHR, while field trials support the introduced main principles.

The problem of a point target detection masked by clutter distributed over range and Doppler, including the range and Doppler of the target, is considered for a multimode propagation scenario commonly encountered in quasimonostatic HF over-the-horizon radars (OTHR). Here, a clutter signal spread in Doppler frequency due to propagation via a disturbed ionospheric layer competes with a target and narrowband clutter returns propagating via a stable ionospheric layer with the same group delay (radar range). Mitigation over all ranges of spread clutter propagating via a ¿mixed mode¿ path with indistinguishable direction-of-arrival (DoA) relative to the target requires (potentially adaptive) transmit beamforming to exploit the direction-of-departure (DoD) difference, which varies as a function of radar range. This range-dependent beamforming can be implemented only via the use of multiple-input multiple-output radar technology. In this paper, we explore the fundamental limitations that exist for the maximal dimension of the area in range-Doppler space occupied by spread clutter and the required properties (cardinality) of the orthogonal waveform set for efficient spread clutter mitigation.

Earth Observation data acquired by the Landsat missions are of immense value to the global community and constitute the world’s longest continuous civilian Earth Observation program. However, because of the costs of data storage infrastructure these data have traditionally been stored in raw form on tape storage infrastructures which introduces a data retrieval and processing overhead that limits the efficiency of use of this data. As a consequence these data have become ‘dark data’ with only limited use in a piece-meal and labor intensive manner. The Unlocking the Landsat Archive project was set up in 2011 to address this issue and to help realize the true value and potential of these data. The key outcome of the project was the migration of the raw Landsat data that was housed in tape archives at Geoscience Australia to High Performance Data facilities hosted by the National Computational Infrastructure (a super computer facility located at the Australian National University). Once this migration was completed the data were calibrated to produce a living and accessible archive of sensor and scene independent data products derived from Landsat-5 and Landsat-7 data for the period 1998–2012. The calibrated data were organized into High Performance Data structures, underpinned by ISO/OGC standards and web services, which have opened up a vast range of opportunities to efficiently apply these data to applications across multiple scientific domains.

Abstract Complex, cyber‐physical systems must be founded on a digital blueprint that provides the most accurate representation of the system by federating information from engineering models across multiple enterprise repositories. This blueprint would serve as the digital surrogate of the system and evolve as the actual system matures across its lifecycle, from conception and design to production and operations. This paper presents a graph‐based approach for realizing the digital blueprint, which we refer to as the Total System Model. The paper is divided into five parts. Part 1 provides an introduction to use cases for model‐based systems engineering. Part 2 introduces graph concepts for the Total System Model. Part 3 provides a demonstration of the graph‐based approach using Syndeia software as a representative application. Part 4 provides a summary of this paper, and Part 5 lays out potential directions for future work.

A novel spacecraft architecture, known as Disturbance–Free Payload (DFP), has been presented and successfully demonstrated experimentally. In this architecture, the payload and the spacecraft are separate bodies that fly in close-proximity formation and interact through non-contact sensors and actuators to achieve precision payload control and isolation from spacecraft disturbances. Vibration isolation is provided down to zero frequency and isolation performance is not limited by sensor characteristics. A thorough set of tests has been conducted using a two-dimensional testbed to determine the level of broadband isolation achieved using this concept. Test configuration modifications and hardware upgrades have resulted in an improvement over prior test results. These recently completed tests demonstrate, in the laboratory, measurement of broadband (0.1-100 Hz) isolation of over 64 dB (a factor of 1700). This measurement far exceeds any space-based vibration isolation experiments and would only improve in a quieter background, such as space. I. Introduction ew advancements in the area of vibration isolation for space applications have been few and far between. Demonstrations of new concepts are equally rare. To meet the stringent pointing and control requirements of future space-based systems, developments in the area of vibration isolation need to be made and demonstrations to validate the concepts are necessary to make them flight worthy. A novel concept, known as Disturbance-Free Payload 1 (DFP), was introduced by Pedreiro 2 . This architecture provides unprecedented control and motion stability for space borne systems. An experimental apparatus was built and used to demonstrate the DFP concept in two dimensions (Ref. 3). The experiment emulates a payload and spacecraft which are mechanically decoupled and contains sensors and actuators for real-time control implementation and performance assessment. The testbed was used to demonstrate operational capabilities, such as pointing, vibration isolation, slew, and momentum dump, and to assess performance. Results from initial tests showed isolation performance in excess of 50 dB. However, these preliminary performance assessment results were limited by sensor noise and actuator capability. Improvements to testing procedures and hardware have resulted in measurements of over 64 dB broadband isolation performance (0.1 Hz-100 Hz), which is well beyond the state-ofthe-art.

This paper presents a new sensor concept designed to provide maritime domain awareness over large ocean areas. The Mode-Selective OTHR introduced herein achieves significant detection and tracking capability against maritime vessels relative to traditional OTHR designs because it is designed specifically to reject disturbed ionospheric propagation modes and operate only using low distortion propagation modes. The architecture of the radar is such that this rejection occurs for both the transmitter-to-surveillance-footprint and the footprint return-to-receiver propagation paths. This is achieved using recently discovered techniques for non-causal adaptive and range dependent transmit beamforming and two-dimensional apertures for both transmission and reception. It also includes new methods for using planar transmit arrays operating with extreme steer angle.