Physical Sciences

Imaging Space System Architectures Using a Granular Medium as a Primary Concentrator

Higher-resolution optics provide improved hyperspectral imaging for ocean and land monitoring, as well as exoplanet detection.

Typically, the cost of a space observatory is driven by the size and mass of the primary aperture. Generally, a monolithic aperture is much heavier and complex to fabricate (hence, more costly) than an aperture of the same size but composed of much smaller units. Formation flying technology, as applied to swarm systems in space, is an emerging discipline.

Posted in: Briefs, TSP, Imaging, Physical Sciences, Architecture, Imaging and visualization

Image Processing Method To Determine Dust Optical Density

Image processing techniques for determining dust optical density in Apollo videos have been developed. The software generates histograms, and calculates the mean and standard deviation, which are then used to match dusty and clear images for the purpose of estimating an effective optical density. A dust thickness model, based on the tilt of the camera and increasing thickness of the dust layer towards the top of the image, is used to account for the distance light travels through dust.

Posted in: Briefs, TSP, Physical Sciences, Imaging and visualization, Optics, Particulate matter (PM)

Vibration and Thermal Cycling Apparatus for Cryogenic Tanks

Key design characteristics can be reliably and repeatedly tested together or separately as required by the design requirements.

Understanding thermal and mechanical behaviors and their inter-dependencies of complex tank systems is crucial to making proper design decisions. Low-maintenance, high-performance systems are becoming more important as global energy demands and efficiency requirements increase.

Posted in: Briefs, TSP, Physical Sciences, Design processes, Vibration

Integrated Rate Isolation Sensor

Sensor allows for fault detection and isolation using only two IMUs.

Some vehicles use an internal measurement unit (IMU) system to determine the speed, acceleration, orientation, position, and/or direction of movement of the vehicle. Vehicles used for high-availability or life-critical systems may employ a fault-tolerant IMU design. Typically, such vehicles use three or more IMUs to detect the failure of an IMU and isolate the failing IMU from the other functional IMUs. A fault-tolerant system having multiple IMUs pays an associated mass, power, and volume penalty for each additional IMU. The mass/power/volume (M/P/V) of a fault-tolerant IMU system is the M/P/V of an individual IMU multiplied by the number of IMUs employed to do fault tolerance. Furthermore, each additional IMU adds to the cost of a fault-tolerant system.

Posted in: Briefs, Physical Sciences, Sensors and actuators

Mercury-Cadmium-Telluride Focal Plane Array for Warm Alignment of Imaging Spectroscopy Systems

This array minimizes the need to cold-cycle instrumentation, reducing cost and time for integration and testing.

A new technique allows a mercury-cadmium-telluride (MCT) focal plane array (FPA) to operate at room temperature. These results were obtained through experimentation by varying the integration time, frame rate, and bias levels to optimize the output when warm.

Posted in: Briefs, Physical Sciences, Imaging and visualization, Test equipment and instrumentation, Test procedures

Enhanced Auditory Alert Systems

Spatial modulation is used to improve the detectability of an alert signal.

Auditory warning systems for human interfaces are often designed around criteria that depend primarily upon signal loudness. It is well understood from the auditory literature that, by making an alert signal substantially louder than the measured background noise level, one can insure that an alert signal will be detectable. Such auditory alert systems have been used in the aviation industry for a number of years in order to raise the awareness of the crew for terrain proximity, for example. However, if an alert signal amplitude is too loud, the alert signal may produce a “startle effect” that hinders performance in some high-stress situations.

Posted in: Briefs, TSP, Physical Sciences, Human machine interface (HMI)

Carbon Monoxide Silicate Reduction System

This system generates high oxygen yields from lunar soil and can be used for the production of ferrosilicon and high-grade silicon metal.

Oxygen produced from lunar resources is a very desirable product to greatly reduce the mass lifted from the Earth’s surface in support of exploration activities. The ability to obtain high yields of oxygen from undifferentiated lunar soils enables planning for near-term piloted missions to the Moon. One technology tested for the production of lunar oxygen has been hydrogen reduction of lunar soils. Oxygen yields from hydrogen reduction are generally between one and four percent of un-beneficiated lunar soil.

Posted in: Briefs, TSP, Physical Sciences, Carbon monoxide

Real-Time Minimization of Tracking Error for Aircraft Systems

Direct adaptive control looks at errors and decides if and when corrections are needed.

In many cases when an aircraft/spacecraft vehicle encounters a failure (such as a jammed control or loss of a part), there are still enough redundant actuation mechanisms to safely maneuver the vehicle. However, most pilots/autonomous systems are unable to adapt to the altered configuration and learn to control the damaged aircraft in the very short time available for safe operation. Fortunately, the flight computer may have the necessary information as well as bandwidth available to learn the new dynamics and determine mechanisms to control the vehicle quickly. The flight computer needs an intelligent controller that flies the vehicle with the baseline controller during normal conditions, and adapts the design when the vehicle suffers damage. Using information about the vehicle from all the available sensors, the system determines whether the vehicle is damaged. Direct adaptive control (DAC) looks directly at the errors, and updates the control law accordingly. This technology looks not just at the tracking error, but rather its characteristics over time to determine whether the controller needs to be adapted or left alone. This is typically fast and meets the timing considerations for aircraft/spacecraft system implementation.

Posted in: Briefs, TSP, Data Acquisition, Physical Sciences, Flight control systems, Safety critical systems, Sensors and actuators

Lunar Organic Waste Reformer

Possible applications also include conversion of terrestrial organic wastes into fuel for power generation or into feedstock for chemical manufacture.

The Lunar Organic Waste Reformer (LOWR) is a novel technology to convert organic wastes from human space exploration outposts into useful propellant constituents. The LOWR meets NASA’s Trash to Supply Gas (TtSG) objective under the Advanced Exploration Systems Logistics Reduction and Repurposing project by integrating steam reformation, methanation, and electrolysis to convert organic waste into methane and oxygen products. At reformer temperatures above 700 °C, oxygenated steam reacts with organic matter to produce a gas mixture largely composed of hydrogen, carbon monoxide, and carbon dioxide. After condensing and removing excess water, the reformer exhaust gases are fed to a catalytic Sabatier reactor where they are combined with supplemental hydrogen at 350 to 500 °C to produce methane and water. The methane product can be liquefied for storage.

Posted in: Briefs, Physical Sciences, Waste management

Digital Laser Frequency Stabilization via Cavity Locking Employing Low-Frequency Direct Modulation

Direct modulation reduces complexity, volume, and mass.

This project’s goal was to simplify laser frequency stabilization. A simpler system will have many benefits, including reduction of power consumption, complexity, volume, mass, and risk of failure. To implement the Pound-Drever-Hall (PDH) technique requires both RF modulation and demodulation electronics, including an electro-optic modulator, a photoreceiver of sufficient bandwidth to detect the RF modulation fields, demodulation electronics of sufficient bandwidth, and an RF function generator. For a space mission, this equipment can be costly and power-hungry, in addition to the difficulty of being rated to operate in the harsh space environment.

Posted in: Briefs, TSP, Physical Sciences, Electronic equipment, Spacecraft

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