Abstract: Multi-spectral methods and systems for the day and night remote sensing (detection, identification, and quantification) of greenhouse gas emission sources from space are provided. The sensor system includes a telescope assembly that passively collects light from an observation area and directs that light through spectral, optical filters and to a sensor array having a plurality of rows and columns of pixels. Different groups of sensor array pixel rows are aligned to receive light that has passed through different optical filters. The filters have passbands corresponding to the reflective and emissive bands of gases of interest, as well as associated reflective and emissive reference bands, and broadband spectral bands. A set of image data frames is obtained as the field of view of the sensor system moves over an observation area and an aggregate image showing locations of detected gas emissions is generated using the collected data.

Abstract: Chemical propellant storage and supply systems and methods for use on spacecraft are provided. The systems and methods include a fluid pump for moving chemical propellant within the system at selected pressures. This can include operating the fluid pump to supply propellant to a thruster system at a selected pressure. A fuel tank can be refilled by connecting a propellant resupply source to the system, and operating the fluid pump to move propellant from the propellant resupply source to the fuel tank. In a system with multiple fuel tanks, the fluid pump can be operated to move propellant from a donor fuel tank to a recipient fuel tank. The chemical propellant can be stored in one or more fuel tanks at a relatively low pressure. In addition, the chemical propellant is not pressurized by a gaseous pressurant while it is stored in the fuel tank.

Abstract: Multi-spectral methods and systems for the day and night remote sensing (detection, identification, and quantification) of greenhouse gas emission sources from space are provided. The sensor system includes a telescope assembly that passively collects light from an observation area and directs that light through spectral, optical filters and to a sensor array having a plurality of rows and columns of pixels. Different groups of sensor array pixel rows are aligned to receive light that has passed through different optical filters. The filters have passbands corresponding to the reflective and emissive bands of gases of interest, as well as associated reflective and emissive reference bands, and broadband spectral bands. A set of image data frames is obtained as the field of view of the sensor system moves over an observation area and an aggregate image showing locations of detected gas emissions is generated using the collected data.

Abstract: Attestation of an electronic device provides assurances that the device is trustworthy and operating as intended or, at least, within acceptable parameters. Methods and systems are provided herein wherein a device under test (DUT) is subject to tests, the results of which are provided to a trust verifier (TV) to indicate whether the DUT passed or failed. To protect the integrity of the test from being discovered by malware, the test logic is developed “off board” and only machine code is provided to the DUT. Similarly, memory values and other data of the DUT are not revealed to the TV, which is only provided with test results.

Abstract: A system for communication is provided. The system includes an emitter transmitting a first code of a first wavelength. The system includes a filter or variable waveplate receiving the first code. The system includes a receiver sensor receiving the filtered first code. The system includes the emitter transmitting a second code of a second wavelength. The system includes the variable waveplate or other filter receiving the second signal. The system includes the receiver sensor receiving the filtered second code. The first and second codes may be used for communication, synchronizing the emitter, and other purposes.

Abstract: Spacecraft propulsion systems and methods featuring a first storage tank containing a metallic propellant and a second storage tank containing a non-metallic propellant are provided. A selected one of the metallic propellant and the non-metallic propellant is supplied to an electric propulsion thruster, depending on an operational mode of the spacecraft. The metallic propellant is stored at a relatively high density, while the non-metallic propellant is stored at a lower density than the metallic propellant. Moreover, the non-metallic propellant is preferably utilized to produce thrust through the electric propulsion thruster during operational maneuvers, while the metallic propellant is reserved for producing thrust through the electric propulsion thruster during end-of-life, such as deorbiting, maneuvers.

Abstract: A spacecraft sunshade is provided. The sunshade includes a surface that is maintained in a sun facing orientation. Adjustments to a position of the sunshade are made in a plane that is transverse to a line of sight to the sun, in order to block sunlight from being directly incident on an instrument associated with the spacecraft. The sunshade can include photovoltaic elements on the sun-facing surface of the sunshade. In addition, the sunshade can be formed from an opaque material, and further from a material that absorbs heat from the sun and reradiate that heat to the instrument. The sunshade can perform stray light blocking, electrical power generation, and radiational heating functions.

Abstract: Imaging systems and methods that enable multiple detectors to be used to capture multiple component images that can be fused to create a composite image of a scene, without introducing gaps in that composite image in areas corresponding to the boundaries of the detectors, are provided. The system includes imaging optics, such as a telescope, that at least in part define an optical path extending between an exit pupil and a focal plane. Field segmentation optics are located within the optical path, to create multiple, partially overlapping component images. At least one detector is provided to produce an image signal representing each of the component images. A composite image is then formed by registering and fusing the component images.

Abstract: Systems and methods for configuring, packaging, and deploying spacecraft are provided. More particularly, spacecraft are configured with statically mounted instruments. An end of the spacecraft to which the instruments are mounted is relatively distant from a spacecraft bus, and has a narrow width relative to the spacecraft bus. During launch multiple overlapping and interleaved spacecraft are disposed radially about a longitudinal axis of the launch vehicle.

Abstract: Star tracker systems and methods are provided. The star tracker incorporates deep learning processes in combination with relatively low cost hardware components to provide moderate (e.g. ˜1 arc second attitude uncertainty) accuracy. The neural network implementing the deep learning processes can include a Hinton's capsule network or a coordinate convolution layer to maintain spatial relationships between features in images encompassing a plurality of features. The hardware components can be configured to collect a blurred or defocused image in which point sources of light appear as blurs, and in which the blurs create points of intersection. Alternatively or in addition, a blurred or defocused image can be created using processes implemented as part of application programming. The processing of collected images by a neural network to provide an attitude determination can include analyzing a plurality of blurs and blur intersections across an entire frame of image data.

Abstract: Optical image sensor systems and process for simultaneously tracking multiple stationary or moving objects to provide attitude and geolocation information are provided. The objects are detected and tracked within subframe areas defined within a field of view of the image sensor system. Multiple objects within the field of view can be detected and tracked using parallel processing streams. Processing subframe areas can include applying precomputed detector data to image data. Image data within each subframe area obtained from a series of image frames is aggregated to enable the centroid of an object within a particular subframe to be located. Information from an inertial measurement unit can be applied to maintain a stationary object, such as a star, at the center of a respective subframe. Ephemeris data can be applied in combination with the information from the IMU to track a resident space object traversing a known trajectory.

Abstract: A Lidar system is provided. The Lidar system includes a laser emitter transmitting a first signal of a first wavelength. The Lidar system includes a filter receiving the first signal. The Lidar system includes a first dichroic filter switch filtering the first signal received by the variable waveplate or other filter. The Lidar system includes a receiver sensor receiving the filtered first signal. The Lidar system includes the laser emitter transmitting a second signal of a second wavelength. The Lidar system includes the variable waveplate or other filter receiving the second signal. The Lidar system includes the first dichroic filter switch filtering the second signal. The Lidar system includes the receiver sensor receiving the filtered second signal. A processor determines a distance of a target based on the received filtered first and second signals.

Abstract: Systems and methods for obtaining images of a lunar surface and cislunar space using a hybrid telescope are provided. One hybrid telescope is carried by each of two spacecraft. Each spacecraft is in an elliptical orbit about the Moon. The periapsides of the spacecraft orbits are 180° apart from one another. In addition, the spacecraft can be phased 180° apart from one another to enable an offset in access times of each telescope to the cislunar and surface domains respectively. The image sensors associated with the telescopes can include a staring mode for collecting images from cislunar space, and a scanning mode for collecting images from the lunar surface.

Abstract: Systems and methods for measuring relative velocities of platforms are provided. More particularly, light of a single wavelength is directed from a primary platform to a secondary platform as a probe signal. A shift in the frequency of the probe signal caused by a different relative velocity of the platforms is measured. The measurement is performed by using a heterodyne signal produced by mixing the return signal with light at a plurality of different, evenly spaced frequencies, provided from a local oscillator in the form of a frequency comb generator. This configuration enables precise measurements of relative velocity over wide range of velocities.

Abstract: Sensor systems and methods that provide an output in the form of a rate at which light is received by unit pixels within a sensor array are provided. Each unit pixel includes a photodetector that generates an electrical charge in response to receiving light, a charge accumulation area, and a comparator. Once the amount of charge in the accumulation area has reached some threshold amount, a counter is incremented. After the counter has been incremented a selected number of times, an output signal is generated, and the time at which the output signal is generated is marked or recorded. Different unit pixels receiving light at different rates therefore generate output signals at different times.

Abstract: Systems and methods for providing a broadband antenna are provided. The antenna can include a current sheet array having a plurality of elements. Each of the elements includes dipole arms. The dipole arms can be configured as first and second dipole arm pairs for transmitting or receiving signals of different polarizations. Capacitive structures are provided between adjacent branch portions of the dipole arms. The capacitive structures extend from a first side of a substrate on which the dipole arms are located towards a second side of the substrate.

Abstract: Radiometer systems and methods that mitigate flicker (1/f) noise are provided. A microwave radiometer system with accuracy impacted by 1/f noise comprises active components which, between measurements, are powered off and on. By powering the active components off and on, 1/f noise is mitigated. Disclosed systems and methods include performing a first measurement with a sensor of a radiometer, after performing the first measurement, switching power to one or more active components of the radiometer off, the active components comprising one or more of an amplifier, a square law detector, and an A/D converter, after switching the power to the one or more active components off, switching the power to the one or more active components on, and after switching the power to the one or more active components on, performing a second measurement with the sensor.

Abstract: Image sensor systems and methods that mitigate the effects of electronic image sensor persistence are provided. The mitigation of persistence is achieved by flooding the pixels of the image sensor with light, saturating all of the pixels, prior to the collection of desired image data. Moreover, after saturating the pixels, but prior to collecting the desired image, the image sensor is reset and operated to take an image of a black scene. Due to persistence from the prior saturation step, the image of the black scene appears as a gray image. The image sensor is then optionally reset and is again saturated. After another reset operation, a desired image is obtained. The gray image is then subtracted from the desired image, to substantially correct for the effects of persistence in that image.

Abstract: Systems and methods for measuring displacements at the picometer level are provided. A system can include a Michelson interferometer having a fixed arm and a measurement arm. As the length of the measurement arm changes, the output supplied to the interferometer from a variable wavelength light source is changed until the intensity of the resulting inference pattern is maximized. The wavelength of the light at the point the interference pattern is maximized is then measured by mixing light from the light source with the output from a frequency comb generator. The resulting frequency measurement is then converted to a length measurement.

Abstract: Antenna test systems and methods are disclosed. An antenna test system as disclosed herein can include an X-Y isolation structure that defines a plurality of unit cells, a plurality of coupling elements, with at least one coupling element within each unit cell, and a Z isolation structure. The size and general configuration of the unit cells are selected to allow the individual antenna elements of an array antenna to be placed within a unit cell. Each unit cell thus isolates an antenna element. The disclosed methods include passing energy between antenna elements and corresponding unit cells to characterize the performance of the antenna. An antenna test system as disclosed herein enables the costs associated with testing phased array antenna systems, including but not limited to antennas used in 5G communication systems, to be reduced as compared to prior techniques.