This PDF file contains the front matter associated with SPIE Proceedings Volume 8385, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

We are reporting on a single frequency pulsed fiber laser based on extremely narrow band volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass. The performance of Yb-doped fiber laser was studied in both passive and active Q-switch schemes. It is shown stable operation in both single TEM00 transverse mode and single longitudinal mode regimes. It generates pulses of 40 - 200 ns duration at a repetition rate of 10 - 100 Hz in active and 17-250 KHz in passive Q-switch configurations with a pulse energy of ~50 μJ, limited by the onset of stimulated Brillouin scattering that leads to fiber fracture.

We review some of our recent results on frequency upconversion. Frequency upconversion of laser pulses at 10.26 μm to those at 1.187 μm was measured in the presence of Nd:YAG laser pulses based on difference-frequency generation in a 10-mm-long GaSe crystal. The highest power conversion efficiency for the parametric conversion was determined to be 20.9%, corresponding to the photon conversion efficiency of 2.42%. This value is two orders of magnitude higher than the highest value reported on GaSe in the literature. The saturation of the output power at 1.187 μm as the input power at 10.26 μm was increased, due to the back conversion, i.e. 1.187 μm + 10.26 μm → 1.064 μm, was clearly evidenced. Besides the midinfrared region, we have also investigated frequency upconversion of the input signals at 1.27 μm and 1.57 μm in the presence of the pump beam at 1.064 μm in bulk periodically-poled LiNbO₃ (PPLN) crystals. The quantum efficiencies of 11.2% and 13.2% have been achieved at these two input wavelengths. The detections of low-level photons at these two wavelengths are important to the NASA Active Sensing of CO₂ Emissions over Nights, Days, and Seasons (ASCENDS) mission.

The innovative, high transmission band-pass filter technology presented here for the mid infrared (IR), terahertz (THz) and submillimeter ranges can tolerate cryogenic temperatures (down to 4K and below), are radiation-hard, vacuum-compatible and vibration-tolerant making them launch-capable and durable for potential space applications. In addition, Lake Shore band-pass filters (BPF) are light weight, as they employ no heavy substrates, nor have any vibronic bands due to polymer support layers. The filters are less than 2 mm thick (mostly the mounting frame) which allows insertion into tight spaces and standard filter wheels. The thin, light weight, vacuum compatible design can be incorporated into almost any detector setup. Filters are available for quick delivery in 29 standard center wavelengths (CWL) with 4 standard diameter sizes, up to 40mm inner diameter (ID).

Broadband focal plane array sensors, operating in the 0.25 to 2.5 μm wavelength range, are an enabling technology for several imaging applications including atmospheric greenhouse gas monitoring. Currently, hyper-spectral imagers use separate image sensors for different spectral sub-bands, for example GaN for UV, Si for visible, and InGaAs for IR, thus requiring expensive component-level integration. Our approach is to manufacture a single image sensor with 0.25 to 2.5 μm spectral range using GaAs substrates, which are commercially available in diameters as large as 6 inches. The key challenges, namely achieving high UV efficiency, low dark current, and high speed operation, are addressed separately in a lattice-matched GaAs UV-to-Visible photodiode and a lattice-mismatched InGaAs NIR-to-SWIR photodiode. The method for monolithically combining the two structures into a single UV-to-SWIR photodiode / photodiode array is also presented.

Resonant cavity quantum efficiency enhancement for near-infrared (NIR) detection in silicon detectors has been extensively reported over the last several years. Cavity thickness uniformity has been achieved mainly by using silicon on insulator (SOI) as starting material. Though this approach yields excellent response uniformity, it lacks the flexibility of controlling the tuning wavelength and it is not suitable for processing in standard silicon CMOS technology. Silicon Geiger avalanche Photodiode (GPD) technology with its single-photon sensitivity and nanosecond integration time has seen accelerated development worldwide due to increased availability and lower cost of silicon processing. However, the technology of fabricating large GPD arrays is being developed at a slower pace, mainly due to the need to customize the readout circuitry (ROIC) to the application (counting, ranging or timing). We are developing the technology to fabricate single-photon, silicon GPD arrays in standard CMOS assembled in flip-chip with dedicated ROIC arrays and add resonant cavity enhancement (RC-GPD) to enhance their response to NIR photons. For manufacturability, processing cost, and process flexibility reasons, we implement the resonant cavity process at the end of the GPD+ROIC array fabrication. We have reviewed at the SPIE DSS 2011 conference the silicon RC-GPD array technology developed at aPeak and have pointed to the design and technological challenges to achieve uniform quantum efficiency response in NIR over large GPD arrays. In this paper, we present the progress on tuning the resonant cavity over large RC-GPD arrays as well as the functional validation of 32x32pixel ROICs designed to operate with such arrays. We also present the radiation hardness data of the silicon GPD array technology (legacy technology used for RC-GPD fabrication) to proton and neutron irradiation.

The growth of the small satellite market and launch opportunities for these satellites is creating a new niche for earth observations that contrasts with the long mission durations, high costs, and long development times associated with traditional space-based earth observations. Low-cost, short-lived missions made possible by this new approach provide an experimental platform for testing new sensor technologies that may transition to larger, more long-lived platforms. The low costs and short lifetimes also increase acceptable risk to sensors, enabling large decreases in cost using commercial off-the-shelf (COTS) parts and allowing early-career scientists and engineers to gain experience with these projects. We are building a low-cost long-wave infrared spectral sensor, funded by the NASA Experimental Project to Stimulate Competitive Research program (EPSCoR), to demonstrate ways in which a university's scientific and instrument development programs can fit into this niche. The sensor is a low-mass, power-efficient thermal hyperspectral imager with electronics contained in a pressure vessel to enable use of COTS electronics and will be compatible with small satellite platforms. The sensor, called Thermal Hyperspectral Imager (THI), is based on a Sagnac interferometer and uses an uncooled 320x256 microbolometer array. The sensor will collect calibrated radiance data at long-wave infrared (LWIR, 8-14 microns) wavelengths in 230 meter pixels with 20 wavenumber spectral resolution from a 400 km orbit. We are currently in the laboratory and airborne testing stage in order to demonstrate the spectro-radiometric quality of data that the instrument provides.

We are currently constructing FalconSAT-7 for launch in late 2013. The low-Earth, 3U CubeSat solar telescope incorporates a 0.2m deployable membrane photon sieve with over 2.5 billion holes. The aim of the experiment is to demonstrate diffraction limited imaging of a collapsible, diffractive primary over a narrow bandwidth. As well as being simpler to manufacture and deploy than curved, polished surfaces, the sheets do not have to be optically flat, greatly reducing many engineering issues. As such, the technology is particularly promising as a means to achieve extremely large optical primaries from compact, lightweight packages.

A concept of a compact device for analyzing key isotopic composition in surface materials without sample preparation is presented. This design is based on an advanced modification of Laser Induced Breakdown Spectroscopy (LIBS). First, we developed Laser Ablation Molecular Isotopic Spectrometry (LAMIS) that involves measuring isotope-resolved molecular emission, which exhibits significantly larger isotopic spectral shifts than those in atomic transitions. Second, we used laser ablation to vaporize the sample materials into a plume in which absorption spectra can be measured using a tunable diode laser. The intrinsically high spectral resolution of the diode lasers facilitates measurements of isotopic ratios. The absorption sensitivity can be boosted using cavity enhanced spectroscopy. Temporal behavior of species in a laser ablation plasma from solid samples with various isotopic composition was studied. Detection of key isotopes associated with signs of life (carbon, nitrogen, hydrogen) as well as strontium and boron in laser ablation plume was demonstrated; boron isotopes were quantified. Isotope-resolved spectra of many other molecular species were simulated. The experimental results demonstrate sensitivity to ⁸⁶Sr, ⁸⁷Sr, and ⁸⁸Sr with spectrally resolved measurements for each of them. It is possible to measure strontium isotopes in rocks on Mars for radiogenic age determination. Requirements for spectral resolution of the optical measurement system can be significantly relaxed when the isotopic abundance ratio is determined using chemometric analysis of spectra.

Even the longest geosatellite, at 40 m, subtends only 0.2 arcsec (1 microradian). Determining structure and orientation with 10 cm resolution requires a 90 m telescope at visual wavelengths, or an interferometer. We de- scribe the application of optical interferometry to observations of complex extended targets such as geosatellites, and discuss some of its challenges. We brie y describe our Navy Optical Interferometer (NOI) group's eorts toward interferometric observations of geosatellites, including the rst interferometric detection of a geosatellite. The NOI observes in 16 spectral channels (550{850 nm) using up to six 12-cm apertures, with baselines (separa- tions between apertures) of 16 to 79 m. We detected the geosatellite DirecTV-9S during glint seasons in March 2008 and March 2009, using a single 16 m baseline (resolution 1:6 m). Fringes on a longer baseline were too weak because the large-scale structure was over-resolved. The fringe strengths are consistent with a combination of two size scales, 1:3 m and & 3:5 m. Our near term NOI work is directed toward observing geosatellites with three or more 10 to 15 m baselines, using closure phase measurements to remove atmospheric turbulence eects and coherent data averaging to increase the SNR. Beyond the two- to three-year time frame, we plan to install larger apertures (1.4 and 1.8 m), allowing observations outside glint season, and to develop baseline bootstrap- ping, building long baselines from chains of short baselines, to avoid over-resolution while increasing maximum resolution. Our ultimate goal is to develop the design parameters for dedicated satellite imaging interferometry.

We present a new active, non-invasive, non-desctructive, in situ spectroscopic method that enable a better understanding of the spatial distribution of microbes, organics, and water on natural surfaces that could support life-detection, organic stability assessment, and in-situ resource utilization missions on planetary bodies. Analytical and spectroscopic methods that have been employed to attempt to address these types of questions provide detection over a limited spatial area, provide either significant false positives/false negatives, or are limited to either morphological or chemical information. Furthermore, apart from the spectroscopic analyses, the methods are limited to invasive treatments that alter the samples or remove critical spatial context. Active spectroscopic methods such Raman and or LIBS have been employed as a means to approach these questions however, traditional Raman scatting is an extremely weak phenomenon and LIBS provides looses information regarding chemical structure. As an alternative, we present the use of deep UV native fluorescence, Raman spectroscopy and hyperspectral imaging from proximity (1-10 cm) to standoff (1-5m). Deep UV native fluorescence, coupled to resonance Raman spectroscopy, can provide a solution that has a means to map large areas with sensitivities to organics, that are expected to be present from meteoritic infall, biosignatures indicating extant or extinct life, and detect the presence of water for in-situ resource utilization. The methodology and the data presented will demonstrate the ability to detect and differentiate organics a natural surface - relevant to Mars and other planetary surfaces, and also elucidate the distribution to enable an understanding of their provenance.

The Multi Mission Bus Demonstrator (MBD) is a successful demonstration of agile program management and system engineering in a high risk technology application where utilizing and implementing new, untraditional development strategies were necessary. MBD produced two fully functioning spacecraft for a military/DOD application in a record breaking time frame and at dramatically reduced costs. This paper discloses the adaptation and application of concepts developed in agile software engineering to hardware product and system development for critical military applications. This challenging spacecraft did not use existing key technology (heritage hardware) and created a large paradigm shift from traditional spacecraft development. The insertion of new technologies and methods in space hardware has long been a problem due to long build times, the desire to use heritage hardware, and lack of effective process. The role of momentum in the innovative process can be exploited to tackle ongoing technology disruptions and allowing risk interactions to be mitigated in a disciplined manner. Examples of how these concepts were used during the MBD program will be delineated. Maintaining project momentum was essential to assess the constant non recurring technological challenges which needed to be retired rapidly from the engineering risk liens. Development never slowed due to tactical assessment of the hardware with the adoption of the SCRUM technique. We adapted this concept as a representation of mitigation of technical risk while allowing for design freeze later in the program's development cycle. By using Agile Systems Engineering and Management techniques which enabled decisive action, the product development momentum effectively was used to produce two novel space vehicles in a fraction of time with dramatically reduced cost.

Leveraging low cost launch carriers for small satellites with the functionality required for DoD and intelligence missions realizes a hidden potential capability. The Multi-Mission Bus Demonstration (MBD) is a Johns Hopkins University Applied Physics Laboratory (JHU/APL) program to demonstrate military operational relevance in a 3U CubeSat form factor. The MBD spacecraft caters to mission versatility and responsive launch capabilities with a standardized bus and interchangeable payload interface design. MBD embraced the challenge of building two space vehicles on an extremely aggressive timeline and demanding budget, causing the development team to evaluate every step of the process to maximize efforts with minimal manpower and cost. MBD is providing a classified DoD payload capability that is truly operationally relevant and may revolutionize the mission area. As a single instrument or payload satellite, also called a SensorSat, MBD is a spacecraft of realizable ISR benefits including effective remote sensing, simplified engineering design and program requirements, and reduced time to launch, all yielding an appealing cost per unit. The SensorSat has potential to detect sufficient information that will act as a complementary component to tactical commanders in heightening battlefield awareness. Recent advancements in technology has put capabilities such as precision navigation, communication intelligence, signal intelligence, tactical warning, environmental intelligence, and a wide variety of ground imaging, at the tip of culmination in a small, economical package. This paper reviews the high functionality of the MBD spacecraft in the miniaturized footprint of 10 cm by 10 cm by 30cm which allows the mission to leverage inexpensive launch opportunities.

The understanding of how humans process information, determine salience, and combine seemingly unrelated information is essential to automated processing of large amounts of information that is partially relevant, or of unknown relevance. Recent neurological science research in human perception, and in information science regarding contextbased modeling, provides us with a theoretical basis for using a bottom-up approach for automating the management of large amounts of information in ways directly useful for human operators. However, integration of human intelligence into a game theoretic framework for dynamic and adaptive decision support needs a perception and cognition model. For the purpose of cognitive modeling, we present a brain-computer-interface (BCI) based humanoid robot system to acquire brainwaves during human mental activities of imagining a humanoid robot-walking behavior. We use the neural signals to investigate relationships between complex humanoid robot behaviors and human mental activities for developing the perception and cognition model. The BCI system consists of a data acquisition unit with an electroencephalograph (EEG), a humanoid robot, and a charge couple CCD camera. An EEG electrode cup acquires brainwaves from the skin surface on scalp. The humanoid robot has 20 degrees of freedom (DOFs); 12 DOFs located on hips, knees, and ankles for humanoid robot walking, 6 DOFs on shoulders and arms for arms motion, and 2 DOFs for head yaw and pitch motion. The CCD camera takes video clips of the human subject's hand postures to identify mental activities that are correlated to the robot-walking behaviors. We use the neural signals to investigate relationships between complex humanoid robot behaviors and human mental activities for developing the perception and cognition model.

The use of a space manipulator (robot) for capturing a tumbling object is a risky and challenging task, mainly because when the manipulator onboard a servicing satellite (base satellite) intercepts with an external object for capture, the resulting impulse will be transferred along the mechanical arm down to the servicing satellite causing disturbance to the attitude of the satellite. Such disturbance may destabilize the servicing satellite if the captured object is tumbling and the physical contact between the robot end-effector and the object is not controlled properly. Certainly, the risk may be mitigated with a force or impedance control capability of the manipulator. However, the implementation of force or impedance control usually requires the robot to have a joint torque sensing and control capability which is a very expensive requirement for a space manipulator. To date, there has never been a really flown space manipulator having a joint torque control capability. Further, even a force or impedance control capability becomes available, much development is still needed before safe capture of a tumbling object can be confidently tried in a real mission. This paper presents an optimal control strategy for a space manipulator to have minimal impact to the base satellite during a capturing operation. The idea is to first predict an optimal future time and motion state for capturing and then control the manipulator to reach the determined motion state such that, when the tip of the robot maneuvers to and intercepts with the tumbling object, a minimal attitude disturbance to the servicing satellite will occur. The proposed control strategy can be implemented regardless whether the manipulator has a joint torque control capability or not. Since the control acts before a physical contact happens, it will not affect but actually augment any existing force or impedance control capability of the manipulator. The proposed method is demonstrated using a simulation example.

One of the major challenges for lunar exploration missions is how to achieve dynamic and robust routing. To reduce the development cost, it is desirable to leverage existing technologies, such as routing in mobile ad hoc networks (MANETs) and delay tolerant networks (DTN). However, these technologies are developed for the Earth environment and hence need further investigation for the lunar environment. To support robust access and dynamic mission operations, we propose a DataBus-based Hybrid Routing (DBHR) approach that combines MANET reactive routing protocol (such as AODV) and DTN-based bundle delivery. Our DBHR approach is designed for a tiered architecture where remote nodes communicate with upper-tier gateways through data carriers (DataBus) using short-range radio interfaces. Our scheme explores the (non)availability of the end-to-end path between two peers using MANET routing and provides diverse route options based upon different parameters. This interaction between hop-by-hop DTN technologies and end-to-end MANET protocol will result in a reliable and robust routing protocol for orbit access and improve the overall communication capabilities. To evaluate its performance, we implemented our proposed scheme on commercial-off-theshelf (COTS) routers with the custom OpenWRT and tailored IBR-DTN bundle protocol distribution. The on-demand service request and grant mechanisms are also developed in our implementation to allow certain DTN nodes to reserve the future access opportunities. Finally, we demonstrate the achieved capabilities and performance gains through experiments on a hardware test bed that consists of several COTS routers with our implementation.

In this paper, software tools for analyzing the communications capabilities of Radio Frequency (RF) ISLs are developed, and validated. The software tools are extremely flexible and can be used for analyzing any freespace RF ISL. The tools explore trade-offs in the communications capability by varying the requirements, parameters, and components of the communications system. Three GUIs are developed. The first GUI can use parameters from any satellite constellation geometry to calculate the operating range of the ISLs including inter-plane ranges between satellites within the same orbit plane as well as ranges between orbital planes within satellite constellation. The second GUI can work with any type of satellite whether it is GEO or LEO and solves for an unknown parameter of the communications system when all other parameters are given. The third GUI extends the analysis capability by plotting the trade-off between two parameters over a specified range of data. These plots analysis of the trade- off parameters for ISLs can indicate the crucial parameters which have the largest effect on system design and allows smooth and efficient design for ISLs.

Real-time cyberspace situational awareness is critical for securing and protecting today's enterprise networks from various cyber threats. When a security incident occurs, network administrators and security analysts need to know what exactly has happened in the network, why it happened, and what actions or countermeasures should be taken to quickly mitigate the potential impacts. In this paper, we propose an integrated cyberspace situational awareness system for efficient cyber attack detection, analysis and mitigation in large-scale enterprise networks. Essentially, a cyberspace common operational picture will be developed, which is a multi-layer graphical model and can efficiently capture and represent the statuses, relationships, and interdependencies of various entities and elements within and among different levels of a network. Once shared among authorized users, this cyberspace common operational picture can provide an integrated view of the logical, physical, and cyber domains, and a unique visualization of disparate data sets to support decision makers. In addition, advanced analyses, such as Bayesian Network analysis, will be explored to address the information uncertainty, dynamic and complex cyber attack detection, and optimal impact mitigation issues. All the developed technologies will be further integrated into an automatic software toolkit to achieve near real-time cyberspace situational awareness and impact mitigation in large-scale computer networks.

Cyber attacks are increasing in frequency, impact, and complexity, which demonstrate extensive network vulnerabilities with the potential for serious damage. Defending against cyber attacks calls for the distributed collaborative monitoring, detection, and mitigation. To this end, we develop a network sensor-based defense framework, with the aim of handling network security awareness, mitigation, and prediction. We implement the prototypical system and show its effectiveness on detecting known attacks, such as port-scanning and distributed denial-of-service (DDoS). Based on this framework, we also implement the statistical-based detection and sequential testing-based detection techniques and compare their respective detection performance. The future implementation of defensive algorithms can be provisioned in our proposed framework for combating cyber attacks.

In this paper, we consider a cognitive radio based space communication system in a game-theoretical framework, where players dynamically interact through wireless channels to utilize the wideband spectrum for their objectives. The performance indices include data rate, covertness, jamming, and anti-jamming; each of which relate to an effective signal-nose-ratio (SNR). The game players have different intents and asymmetric and hierarchical information about the frequency spectrum which are modeled as three different types of players: primary users, secondary users, and hostile active jammers. We consider the informational asymmetry in two situations: (1) different information sets for friendly users and jammers and (2) even among the friendly sensors; some sensors may only have partial or little information about others due to jammed observations. Such an asymmetric information pattern naturally partitions the sensors into leaders and followers. In our hierarchical anti-jammer approach, a two level approach includes a pursuit-evasion game and a Stackelberg game. At the higher-level, a non-cooperative pursuit-evasion game is constructed to model the interactions between jammer and primary users in the frequency-location domains. At the lower level, primary and secondary users play a dynamic Stackelberg game in the presence of jammers. Theoretical game solutions are provided to demonstrate the proposed proactive jamming mitigation strategy.

In this paper a basic cognitive jamming/anti-jamming problem is studied in the context of space communication. The scenario involves a pair of transmitter and receiver, and a cognitive jammer. The cognitive jammer is assumed to have powerful spectrum sensing capability that allows it to detect data transmission from the transmitter to the receiver over the communication channels. Accordingly the jammer uses a "detect and jam" strategy; while the transmitter-receiver side uses the direct frequency hopping spread spectrum approach to mitigate the jamming impact. The basic jamming/anti-jamming problem is formulated as a two-side zero sum game between the jammer and the transmitterreceiver sides. For spectrum sensing, it is assumed that the jammer uses the energy detection in a sliding window fashion, namely, sliding window energy detection. As a conservative strategy of the transmitter-receiver side, Maxmin solutions to the jamming/anti-jamming game are obtained under various conditions. The impacts of factors such as signal propagation delay, channel bandwidth, and jammer/receiver side signal noise ratio on the game results are discussed. The results show the potential threats of cognitive jammers and provide important information for the configuration of jamming resistant space communication networks.

We present a high fidelity cognitive radio (CR) network emulation platform for wireless system tests, measure- ments, and validation. This versatile platform provides the configurable functionalities to control and repeat realistic physical channel effects in integrated space, air, and ground networks. We combine the advantages of scalable simulation environment with reliable hardware performance for high fidelity and repeatable evaluation of heterogeneous CR networks. This approach extends CR design only at device (software-defined-radio) or lower-level protocol (dynamic spectrum access) level to end-to-end cognitive networking, and facilitates low-cost deployment, development, and experimentation of new wireless network protocols and applications on frequency- agile programmable radios. Going beyond the channel emulator paradigm for point-to-point communications, we can support simultaneous transmissions by network-level emulation that allows realistic physical-layer inter- actions between diverse user classes, including secondary users, primary users, and adversarial jammers in CR networks. In particular, we can replay field tests in a lab environment with real radios perceiving and learning the dynamic environment thereby adapting for end-to-end goals over distributed spectrum coordination channels that replace the common control channel as a single point of failure. CR networks offer several dimensions of tunable actions including channel, power, rate, and route selection. The proposed network evaluation platform is fully programmable and can reliably evaluate the necessary cross-layer design solutions with configurable op- timization space by leveraging the hardware experiments to represent the realistic effects of physical channel, topology, mobility, and jamming on spectrum agility, situational awareness, and network resiliency. We also provide the flexibility to scale up the test environment by introducing virtual radios and establishing seamless signal-level interactions with real radios. This holistic wireless evaluation approach supports a large-scale, het- erogeneous, and dynamic CR network architecture and allows developing cross-layer network protocols under high fidelity, repeatable, and scalable wireless test scenarios suitable for heterogeneous space, air, and ground networks.

This paper presents an emitter localization technique based on the fusion of Direction of Arrival (DOA) measurements obtained from two miniature unmanned aerial systems (UAS) and the terrain map of the interested area. The system's objective is to localize an emitter distributed in an area with 2000m radius in real time and the localization error is less than 100m with 95% confidence. In the system, each UAS is equipped with a three-element smart antenna for scanning the desired frequency band, calculating the received signal's spectrum signature and estimating the emitter's elevation and azimuth DOA. The received signal's DOA, spectrum signature, UAS position, and the time that the signal is received (calculated with respected to the pulse per second (PPS) signal of global positioning system (GPS)) are transmitted to the ground control station. At the ground control station, the DOA coming from the two UAS are aligned using the received signal's spectrum signature and time stamp, and then fused with the UAS position and terrain map to localize the emitter. This paper is focused on the localization scheme including the DOA estimation and emitter localization based on data fusion. The simulation conducted shows that azimuth DOA error (about 1.5°) is much smaller than elevation DOA error (about 5°), and the achieved localization error is less than 100m in most cases when the UAS and the emitter are located in an area with radius of 2000m.

GEOScan is a grassroots effort, proposed as globally networked orbiting observation facility utilizing the main Iridium NEXT 66-satellite constellation. This will create a revolutionary new capability of massively dense, global geoscience observations and targets elusive questions that scientists have not previously been able to answer, and will not answer, until simultaneous global measurements are made. This effort is enabled by Iridium as part of its Hosted Payload Program. By developing a common sensor suite the logistical and cost barriers for transmitting massive amounts of data from 66 satellites configured in 6 orbital planes with 11 evenly spaced slots per plane is removed. Each sensor suite of GEOScan's networked orbital observation facility consists of 6 system sensors: a Radiometer to measure Earth's total outgoing radiation; a GPS Compact Total Electron Content Sensor to image Earth's plasma environment and gravity field; a MicroCam Multispectral Imager to measure global cloud cover, vegetation, land use, and bright aurora, and also take the first uniform instantaneous image of the Earth; a Radiation Belt Mapping System (dosimeters) to measure energetic electron and proton distributions; a Compact Earth Observing Spectrometer to measure aerosol-atmospheric composition and vegetation; and MEMS Accelerometers to deduce non-conservative forces aiding gravity and neutral drag studies. Our analysis shows that the instrument suites evaluated in a constellation configuration onboard the Iridium NEXT satellites are poised to provide major breakthroughs in Earth and geospace science. GEOScan commercial-of-the-shelf instruments provide low-cost space situational awareness and intelligence, surveillance, and reconnaissance opportunities.

This paper provides an overview of the satellite based Sapphire Payload developed by COM DEV to be used for observing Resident Space Objects (RSOs) from low earth orbit by the Canadian Department of National Defence. The data from this operational mission will be provided to the US Space Surveillance Network as an international contribution to assist with RSO precision positional determination. The payload consists of two modules; an all reflective visible-band telescope housed with a low noise preamplifier/focal plane, and an electronics module that contains primary and redundant electronics. The telescope forms a low distortion image on two CCDs adjacent to each other in the focal plane, creating a primary image and a redundant image that are offset spatially. This combination of high-efficiency low-noise CCDs with well-proven high-throughput optics provides a very sensitive system with low risk and cost. Stray light is well controlled to allow for observations of very faint objects within the vicinity of the bright Earth limb. Thermally induced aberrations are minimized through the use of an all aluminum construction and the strategic use of thermal coatings. The payload will acquire a series of images for each target and perform onboard image pre-processing to minimize the downlink requirements. Internal calibration sources will be used periodically to check for health of the payload and to identify, and possibly correct, any pixels with an aberrant response. This paper also provides a summary of the testing that was performed and the results achieved.

Earth impactors (EIs) pose a significant threat. Upon EI detection, a response mission is required. The proposed architecture is suitable for responding to 75% of EIs. For rapid response, the reconnaissance and the tactical nuclear intervener craft are launched in close succession. The extended response timeframe allows collected data analysis before launching an intervener craft to slowly shift the EI's orbit. A small spacecraft equipped with a radio science package, visual camera, multi-spectral imager, LIDAR and, optionally, a radar tomography sensor will be used for reconnaissance. Sensor tasking and control will be autonomous based on controller-supplied objectives.

Multiple hypothesis tracking methods are under development for space surveillance and one challenge is the accurate and timely orbit initiation from sets of uncorrelated optical observations. This paper develops gating methods for correlation of optical observations in space surveillance. A pair gate based on the concept of an admissible region is introduced. By implementing a hierarchy from fast, but coarse, to more expensive, but accurate gates, the number of hypotheses to be considered for initial orbit determination is reduced considerably. Simulation results demonstrate the effectiveness of the gating procedure, address gate parameter determination, and study the accuracy of initial orbits.

Tens of thousands of debris are expected in the near future in the most critical Low Earth Orbit regimes, hence representing a serious threat for European space assets. In the frame of the Space Situational Awareness (SSA) Preliminary Programme of the European Space Agency, the design of a ground-based phased array radar - aimed at debris detection and tracking - has been proposed. The sensor will provide regularly new measurements of objects' orbital parameters to the cataloguing centre. Track-while-Scan survey has been proposed for efficiently covering a wide volume of the sky, whereas Active Tracking tasks might be engaged in order to improve the tracking performance on specific targets. Concepts for combining Survey/Tracking tasks and managing the radar resources are analysed in this paper against the requirements dictated by SSA collision warning services.

All space instruments contain mechanisms or moving mechanical assemblies that must move (sliding, rolling, rotating, or spinning) and their successful operation is usually mission-critical. Generally, mechanisms are not redundant and therefore represent potential single point failure modes. Several space missions have suffered anomalies or failures due to problems in applying space mechanisms technology. Mechanisms require a specific qualification through a dedicated test campaign. This paper covers the design, development, testing, production, and in-flight experience of the PICARD/SODISM mechanisms. PICARD is a space mission dedicated to the study of the Sun. The PICARD Satellite was successfully launched, on June 15, 2010 on a DNEPR launcher from Dombarovskiy Cosmodrome, near Yasny (Russia). SODISM (SOlar Diameter Imager and Surface Mapper) is a 11 cm Ritchey-Chretien imaging telescope, taking solar images at five wavelengths. SODISM uses several mechanisms (a system to unlock the door at the entrance of the instrument, a system to open/closed the door using a stepper motor, two filters wheels using a stepper motor, and a mechanical shutter). For the fine pointing, SODISM uses three piezoelectric devices acting on the primary mirror of the telescope. The success of the mission depends on the robustness of the mechanisms used and their life.

Acquiring optical images of space objects is one of the most important goals of space-based optical surveillance systems. However, it's actually difficult to obtain enough high resolution optical images for space object recognition, attitude measurement and situational awareness. To solve this problem, the imaging model of space-based optical camera and the imaging characteristics of space objects are analyzed in this paper, and a novel method of image simulation is proposed. The high resolution images of space objects simulated by our method are visually similar to the actual imaging results and may provide data support for further research on space technology.

The increase in the number of satellites and space debris in low Earth orbit (LEO) makes tracking these objects and avoiding collisions a major endeavor. A particularly important issue is the determination of the altitude of these objects, which in many cases is not known with a precision better than 1 km. Here we present the idea of using simultaneous observations by 2 optical telescopes, separated by a few hundred km, to refine the altitude measurement of these objects to a precision of 10 m. We discuss the requirements for such a system, like aperture, timing precision, and the precision to which one needs to know the positions of the telescopes and background stars.