There are many vital issues which are impacting our daily lives and will continue to haunt us as long as we live on this planet of ours. These issues range from food supply availability, drought, coastal zone erosion, volcanoes, hurricanes, terrorism, global warming, earthquakes, water resources, air quality, public health, and agriculture production. Such societal needs are directly linked to our geometric population growth, and abundance of automobiles, industrial emissions, industrial waste and extensive fishing of our oceans and elimination of our ecology. The questions which require serious thoughts, research, coordination, and resources to understand, plan and strike a sensible balance in our daily lives and the above issues are tough to deal with. However, with the advent of remote sensing technologies, tremendous progress has been made in applying space-based and airborne data and products in solving real societal problems. Several of these problems, such as coastal zone erosion, air quality, severe weather, water availability and quality, public health, fires, land slides and others are intricately related; and in the long run can have serious consequences if not properly addressed by scientists, regulatory bodies and policy makers. Although it is a much involved and tangled web to unravel, nevertheless we have an excellent start in understanding some of the phenomena and hopefully can mitigate some of the severe effects by advancing our scientific knowledge. This paper briefly discusses the applications of remote sensing data from Terra, Aqua, and other NASA satellites how to deal with such complex problems; it provides an excellent start.

NASA has recently re-confirmed their interest in autonomous systems as an enabling technology for future missions. In order for autonomous missions to be possible, highly-capable relative sensor systems are needed to determine an object’s distance, direction, and orientation. This is true whether the mission is autonomous in-space assembly, rendezvous and docking, or rover surface navigation. Advanced Optical Systems, Inc. has developed a wide-angle laser range and bearing finder (RBF) for autonomous space missions. The laser RBF has a number of features that make it well-suited for autonomous missions. It has an operating range of 10 m to 5 km, with a 5° field of view. Its wide field of view removes the need for scanning systems such as gimbals, eliminating moving parts and making the sensor simpler and space qualification easier. Its range accuracy is 1% or better; its bearing accuracy, 0.1°. It is designed to operate either as a stand-alone sensor or in tandem with a sensor that returns range, bearing, and orientation at close ranges, such as NASA’s Advanced Video Guidance Sensor. We have assembled the initial prototype and are currently testing it. We will discuss the laser RBF’s design and specifications.

Interacting with computer technology while wearing a space suit is difficult at best. We present a sensor that can interpret body gestures in 3-Dimensions. Having the depth dimension allows simple thresholding to isolate the hands as well as use their positioning and orientation as input controls to digital devices such as computers and/or robotic devices. Structured light pattern projection is a well known method of accurately extracting 3-Dimensional information of a scene. Traditional structured light methods require several different patterns to recover the depth, without ambiguity and albedo sensitivity, and are corrupted by object motion during the projection/capture process. The authors have developed a methodology for combining multiple patterns into a single composite pattern by using 2-Dimensional spatial modulation techniques. A single composite pattern projection does not require synchronization with the camera so the data acquisition rate is only limited by the video rate. We have incorporated dynamic programming to greatly improve the resolution of the scan. Other applications include machine vision, remote controlled robotic interfacing in space, advanced cockpit controls and computer interfacing for the disabled. We will present performance analysis, experimental results and video examples.

With the loss of the Space Shuttle Columbia, there has been intense focus at NASA on being able to detect and characterize damage that may have been sustained by the orbiter during the launch phase. To help perform this task, the Neptec Laser Camera System (LCS) has been selected as one of the sensors to be mounted at the end of a boom extension to the Shuttle Robotic Manipulator System (SRMS). A key factor in NASA’s selection of the LCS was its successful performance during flight STS-105 as a Detailed Test Objective (DTO). The LCS is based on a patented designed which has been exclusively licensed to Neptec for space applications. The boom will be used to position the sensor package to inspect critical areas of the Shuttle’s Thermal Protection System (TPS). The operational scenarios under which the LCS will be used have required solutions to problems not often encountered in 3D sensing systems. For example, under many of the operational scenarios, the scanner will encounter both commanded and uncommanded motion during the acquisition of data. In addition, various ongoing studies are refining the definition of what constitutes a critical breach of the TPS. Each type of damage presents new challenges for robust detection. This paper explores these challenges with a focus on the operational solutions which address them.

The tragic loss of the Space Shuttle Columbia and crew in 2003 has resulted in a requirement to inspect the Shuttle Thermal Protection System (TPS) on-orbit so that the crew may remain at the International Space Station (ISS) in the event of damage that might pose an unacceptable risk to their safe return. An instrumented inspection boom manipulated and operated from the Shuttle’s Canadarm will provide an interim solution for the initial flights. However, a longer term solution has been planned that will permit the required inspection to be performed from within the ISS through the ISS windows. This plan involves the Shuttle performing a pitching maneuver to expose the underside for inspection purposes as it approaches the ISS prior to docking. The central approach in this plan is for the ISS crew to photograph the Shuttle TPS through the ISS windows using high-definition cameras. As an augmentation to this plan, the ISS-based Shuttle Inspection Lidar, or I-SIL, is a proposed lidar instrument that will generate a 3D topographic surface of the Shuttle underside to enable rapid identification and volumetric analysis of tile damage to generate safety and repair data. This paper presents the mission requirements and derived requirements for I-SIL, analyzes specific details of the inspection requirements, and discusses various phases of operating scenarios. The conclusion of the paper outlines the current status of the proposed technology.

Structured light projection is one of the most accurate non-contact methods for scanning surface topologies. The field of view of such a scan may range from millimeters to several meters. One of the most precise and robust methods of structured light is Phase Measuring Profilometry. This method utilizes a sinusoidal pattern that is laterally shifted across a surface. An image is captured at uniform intervals and the “phase” is recovered for each pixel position by correlating across the shifted patterns. In general, the more pattern shifts and the higher the spatial frequency, the more accurate the depth measurement becomes, at each pixel location. However, with a high frequency, ambiguity errors can occur, so a dual frequency approach is commonly used where a low frequency pattern is used for non-ambiguous depth, followed by high frequency pattern. The low frequency result is used to unwrap the high frequency to yield a non-ambiguous and precise phase. If the high frequency is too high, then ambiguity errors will occur. The solution is a multi-frequency method. We present experimental results for several variations of the multi-frequency approach yielding accuracies of 0.127mm standard deviation in depth with 0.92mm pixel spacing. With consumer camera mega pixel technology this equates to a 0.127mm deviation over a field of view of 2 to 3 meters. To achieve this level of accuracy also requires calibration for radial and perspective distortions. Applications for this technology include non-contact surface measurement and robotic and computer vision.

Servicing satellites on-orbit requires ability to rendezvous and dock by an unmanned spacecraft with no or minimum human input. Novel imaging sensors and computer vision technologies are required to detect a target spacecraft at a distance of several kilometers and to guide the approaching spacecraft to contact. Current optical systems operate at much shorter distances, provide only bearing and range towards the target, or rely on visual targets. Emergence of novel LIDAR technologies and computer vision algorithms will lead to a new generation of rendezvous and docking systems in the near future. Such systems will be capable of autonomously detecting a target satellite at a distance of a few kilometers, estimating its bearing, range and relative orientation under virtually any illumination, and in any satellite pose. At MDA Space Missions we have developed a proof-of-concept vision system that uses a scanning LIDAR to estimate pose of a known satellite. First, the vision system detects a target satellite, and estimates its bearing and range. Next, the system estimates the full pose of the satellite using a 3D model. Finally, the system tracks satellite pose with high accuracy and update rate. Estimated pose provides information where the docking port is located even if the port is not visible and enables selecting more efficient flight trajectory. The proof-of-concept vision system has been integrated with a commercial time-of-flight LIDAR and tested using a moving scaled satellite replica in the MDA Vision Testbed.

SALLI is a conceptual instrument design that will efficiently acquire altimetric data for a planetary body or asteroid from orbit while maintaining a minimum power demand. SALLI scans its measurements off-nadir using a novel circular scanning technique that simultaneously permits a large instrument aperture using a motion-bandwidth efficient scanning mechanism. By combining spacecraft ephemeris data with SALLI’s measurement set, a complete digital elevation map of a planet or similar body can be generated in less time and using less spacecraft power than similar scanning and multi-beam instruments designed for the same purpose. SALLI was originally designed to generate measurement data to produce a topographical map of the lunar surface from a polar-orbiting host spacecraft; however, its benefits extend to a variety of other mapping missions of planets or asteroids.

The Spaceborne Scanning Lidar System (SSLS) system is a space qualified scanning lidar system developed by MDA, Space Missions (MD Robotics) and Optech. It is scheduled to be launched in 2005 as part of a one year on-orbit demonstration of space technologies associated with spacecraft autonomous rendezvous and proximity operations. The SSLS was designed to meet specific performance requirements under all lighting conditions during its one-year mission. Prior to delivery to the customer, the SSLS completed a successful proto-flight testing program that demonstrated SSLS capability to perform its intended mission in its target space environment. The SSLS is a product of a successful fusion of proven terrestrial lidar technologies with space proven hardware and software designs. The SSLS product was developed, qualified and delivered to a customer within an extremely demanding schedule. This paper describes the requirements, design constraints and architecture of the SSLS. The paper includes scan results which demonstrate its performance and capabilities at short and long ranges.

We have developed a concept design for a large (~10k × 10k) CMOS imaging array whose elements are grouped in small subarrays with N pixels in each. The subarrays are code-division multiplexed using the Hadamard Transform (HT) based encoding. The Hadamard code improves the signal-to-noise (SNR) ratio to the reference of the read-out amplifier noise by a factor of N^1/2. This way of grouping pixels reduces the number of hybridization bumps by N. A single chip layout has been designed and the architecture of the imager has been developed to accommodate the HT based multiplexing into the existing CMOS technology. The imager architecture allows for a trade-off between the speed and the sensitivity. The envisioned imager would operate at a speed >100 fps with the pixel noise < 20 e^-. The power dissipation would be ~ 100 pW/pixel. The combination of the large format, high speed, high sensitivity and low power dissipation are very attractive for space applications.

Custom-designed charge-coupled devices (CCD) for Gas and Aerosols Monitoring Sensorcraft instrument were developed. These custom-designed CCD devices are linear arrays with pixel format of 512x1 elements and pixel size of 10x200 μm². These devices were characterized at NASA Langley Research Center to achieve a full well capacity as high as 6,000,000 e^-. This met the aircraft flight mission requirements in terms of signal-to-noise performance and maximum dynamic range. Characterization and analysis of the electrical and optical properties of the CCDs were carried out at room temperature. This includes measurements of photon transfer curves, gain coefficient histograms, read noise, and spectral response. Test results obtained on these devices successfully demonstrated the objectives of the aircraft flight mission. In this paper, we describe the characterization results and also discuss their applications to future mission.

Phase-only spatial light modulators provide active pattern projection. Unlike incoherent techniques, the pattern energy is inversely proportional to the total pattern area. If the patterns consist of spots or regions of light energy, it is possible to achieve a high signal-to-noise ratio within these regions. A 3DV Systems’ Zmini range finder works with fast switching of the illumination source to form the “light wall” and fast gating of the reflected image entering the camera. Zmini operates by using a high speed shutter to temporally clip the energy field going to one camera chip while allowing the full pulsed energy to go to a second camera chip. The second chip captures the albedo which is effectively pixelwise divided out of the shuttered chip, leaving values that are proportional to depth. Thus, video rate time of flight depth information is attained. By combining these two technologies, we can extend the operating range of the Zmini shuttered depth finder significantly. In this paper, we present a feasibility report on the range property of the Zmini. The spatial light modulator under investigation is a 512 × 512 element, phase-only, liquid crystal device recently produced by Boulder Non-linear Systems Incorporated.

The design of the diode-pumped gain medium is critical to the successful deployment of lasers in space-based missions. We have developed a number of diode-pumped, conductively cooled zigzag slab designs for this application. These designs include both one-sided and two-side pumped and cooled designs. In one of the one-sided pumped and cooled amplifier designs we optimized the efficiency by maximizing the overlap between the extracting beam and the diode pumps at the total internal reflection (TIR) surface, a so-called “pump on bounce” approach. With this approach we achieved an electrical to optical efficiency from the amplifier of over 11% with an output beam M² of approximately 3. By reducing the size of the extracting beam to reduce diffraction effects in the slab the beam quality could be improved to an M² of 1.5 but the amplifier electrical to optical efficiency dropped to 6.7%. The other one-sided approach we have investigated is a near Brewster angle slab that incorporates beam propagation parallel to the slab axis and achieves good efficiency by a high overall volume fill factor. In a high beam quality oscillator (M² = 1.2) we achieved over 6% electrical to optical efficiency with a Brewster angle head design. Modeling of the thermal effects in both approaches has been performed and will be reported on. The final design approach we have investigated is based on two-sided pumping and cooling. Both modeling and preliminary experimental results indicate that this approach will allow scaling to higher average powers while still maintaining beam qualities and extraction efficiencies at least as good as those obtained with the one-sided pumped and cooled approaches. From the results of these tests and analyses, we have developed a design for a space-qualifiable 1 J, 100 Hz laser operating at 1064 nm.

The tragic loss of Space Shuttle Columbia threw the future of Hubble Space Telescope (HST) in doubt. The Columbia Accident Investigation Board report led NASA to the realization that astronauts must have someplace to go on orbit if the Shuttle is damaged, a requirement that cannot be met for a manned HST mission. Yet missions to HST are required, since HST was designed to be serviced periodically. To address this problem, NASA is developing a robotic servicing mission to Hubble. On-orbit rendezvous and docking under tele-robotic or fully autonomous control involves a number of challenges that have not been fully resolved. One key challenge is how to bring two craft together in precise alignment to each other without an experienced astronaut on board. For this to be possible, sensors are needed to report relative distance, bearing, and orientation. At Advanced Optical Systems (AOS), we have applied our ULTOR digital correlation system to the Hubble repair mission. The ULTOR system operates at approximately 10 Hertz and can accurately determine the relative distance, bearing, and orientation needed for semi- or fully-autonomous docking to HST. The system can operate using the HST berthing target or other features, including the HST itself. It is small and light enough to be placed on the servicing craft, thus avoiding orbit-to-ground communication latency issues. We will discuss the results of our testing with computer-generated imagery of the HST and with any hardware-in-the-loop simulations.

Optical sparse-aperture telescopes represent a promising new technology to increase the effective diameter of an optical system while reducing its weight and stowable size. The sub-apertures of a sparse-aperture system are phased to synthesize a telescope system that has a larger effective aperture than any of the independent sub-apertures. Sparse-apertures have mostly been modeled to date using a "gray-world" approximation where the input is a grayscale image. The gray-world model makes use of a "polychromatic" optical transfer function (OTF) where the spectral OTFs are averaged to form a single OTF. This OTF is then convolved with the grayscale image to create the resultant sparse-aperture image. The model proposed here uses a spectral image-cube as the input to create a panchromatic or multispectral result. These outputs better approximate an actual system because there is a higher spectral fidelity present than a gray-world model. Unlike its Cassegrain counterpart that has a well behaved OTF, the majority of sparse-aperture OTFs have very oscillatory and attenuated natures. When a spectral sparse-aperture model is used, spectral artifacts become apparent when the phasing errors increase beyond a certain threshold. This threshold can be based in part on the type of phasing error (i.e. piston, tip/tilt, and the amount present in each sub-aperture), as well as the collection conditions, including configuration, signal-to-noise ratio (SNR), and fill factor. This research addresses whether integrating a restored multispectral sparse-aperture image into a panchromatic image will decrease the amount of spectral artifacts present. The restored panchromatic image created from integrating multispectral images is compared to a conventional panchromatic sparse-aperture image. Conclusions are drawn through image quality analysis and the change in spectral artifacts.

In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable optical magnification with no macroscopic moving parts. Changing the effective focal length and magnification of an imaging system can be accomplished by adeptly positioning two or more active optics in the optical design and appropriately adjusting the optical power of those elements. In this application, the active optics (e.g. liquid crystal spatial light modulators or deformable mirrors) serve as variable focal-length lenses. Unfortunately, the range over which currently available devices can operate (i.e. their dynamic range) is relatively small. Therefore, the key to this concept is to create large changes in the effective focal length of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses.

Micromachined deformable membrane mirrors (MDMMs) are currently being integrated into or proposed for numerous space-based imaging applications, including systems that utilize phase diversity, foveated imaging, and active or adaptive optical zoom. In stark contrast to applications that require only a few waves of optical stroke, such as atmospheric turbulence correction, these applications often require that the mirrors operate over much larger dynamic ranges. In order to obtain near diffraction-limited performance, these mirrors must be capable of producing wavefronts with accurate figures to within a quarter-wave (P-V). Recent experimental results will be discussed, in which MDMMs produced focal lengths as low as 2.5m with near diffraction-limited performance.

Micro-Electro-Mechanical Systems or MEMS are becoming increasingly important in several optical applications. In particular, devices composed of an array of active micro-optics can be used for wavefront correction, optical switching, and generic digital light control. Whatever the application, it is important for anyone seeking to employ this technology to use computer modeling to predict the performance of the subsystem that incorporates optical MEMS. In this paper we will show how commercially available software can be used to model these systems using several approaches.

Adaptive optics techniques have been proved in both laboratory and field tests to the satisfaction especially of the astronomical and surveillance communities. Such success have sparked interests in other fields, however, to increase efficiency and lower costs new technologies have to be brought to fruition. MEMs are becoming a very important player in this arena. In this paper we describe a portable adaptive optics (AO) system that has been tested in both laboratory and field experiments. Results of these tests will be discussed. Capabilities and shortcomings of this technology will be discussed. A look at future applications and trends will be given.

This paper describes a systematic shape tuning procedure of adaptive structures for MEMS actuator applications. Due to fabrication process variations, MEMS devices can have different shapes with varied deflections. Such shape variations should be corrected for specific applications. As a result, it is necessary to establish a shape tuning procedure. Finite element modeling and optimization approach were used to minimize the shape variations. The procedure integrated Python programming, ABAQUS, and optimization algorithm for engineering applications. It used the powerful Python scripts programming, the vast library of ABAQUS functions, and a robust preexisting optimization algorithm, NLPQL, which provides more efficient, flexible, and systematic tools for optimization problems. Optimization was used in the adaptive structural designs and the shape tuning procedure after the assembly. Using this approach, three bimorph, gold-on-polysilicon, samples with different initial shapes were studied for shape tuning. The shape was characterized by maximum tip deflection resulting from thermo-mechanical deformations. The standard deviation of the shape variations was reduced from 1.21 to 0.05 μm after tuning. This reduction was verified by experimental data. Another case with ten devices was studied to confirm the effectiveness of the procedure. The standard deviation of the deflections was reduced from 0.81 to 0.02 μm after tuning. These results demonstrated the effectiveness of the optimum procedure for shape tuning. This general-purpose systematic methodology can be applied to adaptive structures for a variety of aerospace applications.

Micro Electro-Mechanical Systems (MEMS) based capacitive pressure sensors are typically fabricated using silicon micromachining techniques. In this paper, novel Liquid Crystal Polymer (LCP) based capacitive pressure sensors, fabricated using printed circuit processing techniques, are reported. LCP exhibits good dimensional stability, material flexibility, high chemical resistance, and extremely low moisture absorption, which make it suitable for MEMS applications. Each sensor consists of an LCP substrate, an LCP spacer layer with circular holes, and top LCP layer. The portion of the top LCP layer located above the circular hole of the spacer layer serves as the circular diaphragm of the pressure sensor. A typical pressure sensor with a diaphragm radius of 1.6 mm provides a net capacitance change of 0.18 pF for an applied pressure in the range of 0-70 kPa. Hundreds of such sensors can be batch fabricated cost effectively using existing flexible printed circuit technology.

This paper reports a MEMS-based electrostatically tunable microstrip patch antenna fabricated using printed circuit processing techniques. The microstrip patch is patterned on the top side of the flexible kapton polyimide film, which is suspended above the fixed ground plane using a spacer. The air gap between the microstrip patch and the ground plane is decreased by applying a DC bias voltage between the patch and the ground plane. A decrease in air gap increases the effective permittivity of the antenna resulting in a downward shift in the resonant frequency. The microstrip patch is excited by a slot in the ground plane, which is inductively coupled by a coplanar waveguide (CPW) feed line. A 6 mm x 6 mm microstrip patch antenna tunable from 18.34 GHz at 0 V to 17.95 GHz at 268 V (with a tuning range of 390 MHz) is discussed.

There is an urgent need for biosensors that are able to detect and quantify the presence of a small amount of biological threat agents in a real-time manner. The magnetostrictive microcantilever (MSMC) as the biosensor platform is reported in this paper. The resonance behavior and the sensitivity of MSMC as sensor platform were characterized and compared to the theoretical calculation. The stability and the performance of the MSMC in liquid are studied. The feasibility of MSMC as a high performance biosensor platform is demonstrated by detecting yeast cells in real-time manner used MSMC based-biosensor. Compare to current microcantilevers, the MSMCs have following advantages: 1) remote/wireless driving and sensing; 2) easy to fabricate. More importantly, the MSMC exhibits very high quality merit factor (Q value).

Thin-film MEMS are essential to realization of intelligent integrated microsystems. Of critical importance in such microsystems is the determination and control of mechanical properties in the thin films used for construction of the MEMS, which can be the decisive factor in the realization and subsequent performance, reliability, and long-term stability of the system. In future microsystems the need to fabricate MEMS on temperature sensitive, non-standard substrates will be of particular importance. In this work, mechanical properties of low-temperature (50-300°C) plasma-enhanced chemical vapour deposited silicon nitride thin films have been investigated using depth sensing indentation. Young’s modulus, E, and hardness, H, values obtained for the examined film/substrate bilayers were found to vary asymptotically from the thin film properties for shallow indents to the substrate properties for deep indents. A simple empirical formulation is shown to relate E and H obtained for the film/substrate bilayers to corresponding material properties of the constituent materials via a power-law relation. The temperature of the deposition process was found to strongly influence the thin film mechanical properties. Values of E ~ 150-160GPa and H ~ 14-15GPa were observed for depositions above 225°C. Decreasing the deposition temperature initially caused a moderate and linear decrease in E and H parameters, which was followed by an abrupt decrease in E and H once the deposition temperature was lowered below 100°C, such that E ~ 50GPa and H ~ 3.5GPa at a deposition temperature of 50°C.

This paper describes the Militarily Critical Technologies Program (MCTP) sponsored by the Office of the Director, Defense Research and Engineering (DDR&E). It outlines the unique Technology Working Group (TWG) process developed for use at the Institute for Defense Analyses (IDA) to support this program. It outlines the approach used to determine militarily critical technologies as well as how worldwide technology capability assessments are incorporated into the review process. This paper outlines the MCTP parameters associated with Space Sensors and identifies how both military and commercial applications have an input into the process. The membership of the TWGs is broad based including government, industry and academia technical experts in their respective fields.

Historically diamond machining has been applied to infrared applications because of the more forgiving requirements for figure and finish. These machines were typically configured as lathes or flycutters, enabling them to produce flats and rotationally symmetric surfaces including off-axis aspheres that were within their “swing” capacity. Recent technology improvements in machine position resolution, motion control, diamond tool quality, and fixturing techniques have allowed both visible and UV optics to be successfully produced. Furthermore, additional axes of control have further extended capabilities to include free-form components such as segments of very large “parents”, bi-aspheres, aspheric cylinders, as well as phase plates. Proprietary configurations now allow production of lens arrays, image slicers, gratings, corner cube arrays, as well as prismatic structures. Advances in post-processing reduce diffractive effects and allow the direct figuring of aluminum. This paper will present the results of these new technologies and processes as applied to space borne components and systems.

Proximity operations between orbital vehicles require precise knowledge of relative navigation states. Retro-reflectors may be used by proximity operations navigation sensors as part of the navigation sensor system, to indicate the position of fixed points on one of the vehicles so that relative state data may be calculated. Use of corner cube retro-reflectors in an orbital navigation sensor required detailed ray-tracing analysis to define the expected return signal levels, signal/noise ratios, and predicted error effects due to reflector geometry and optical characteristics. Conventional corner cube reflector images would have displayed image artifacts due to corner cube bevels, interfering with software interpretation of sensor image data. This design avoided software errors due to bevel effects. Special optical design features were required to permit use of multiple target sets, enabling successful tracking over a 1 to 200 meter effective range. We have used this mounting scheme to create corner cube targets for use with the Advanced Video Guidance Sensor (AVGS) on the Orbital Express mission. We discuss our design, the finite-element analysis done on the design, and the results of sensor performance testing with the targets.