Mechanical & Fluid Systems

Hydraulic Pressure Distribution System

This mechanism enhances the performance of mechanically impeding elements in an on-command operational exoskeleton.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Human operation in space over long time periods causes bone and muscle deterioration, so there is a need for countermeasures in the form of physical exercises consisting of working against controlled resistivity. Generally, there are three types of exercise machines that are used by space crews to maintain their fitness: the Crew Exercise Vibration Isolation System (CEVIS), the Treadmill Vibration Isolation System/Second ISS Treadmill (TVIS/T2), and the Advanced Resistive Exercise Device (ARED). These machines have the limitations of very large mass (some weigh about a ton), large operational volumes, cumbersome design, and the need to compensate the generated vibrations and large shifting of the center of mass. They also require interrupting the astronauts’ duties to perform the exercises, as well as requiring periodic costly maintenance. The disclosed de vice provides key elements to enabling the design and operation of compact exercise machines that overcome many of the disadvantages of the current exercise machines found on space vehicles/stations.

Posted in: Briefs, Mechanical Components, Automation, Downsizing, Medical, health, and wellness, Personnel, Lightweighting

Dust Tolerant Connectors

The ruggedized housing for electrical or fluid connectors is designed to withstand harsh environments and rough handling.

John F. Kennedy Space Center, Florida

NASA’s Kennedy Space Center has developed a novel ruggedized housing for an electrical or fluid umbilical connector that prevents intrusion of dust, sand, dirt, mud, and moisture during field use under harsh conditions. The technology consists of a pair of hand-sized protective umbilical interface housings, each containing a connector with an integrated end cap. When the end cap covers the connector, the connector is protected. Each housing has a unique lever assembly connected to the end cap that, when squeezed, flips the end cap up to expose the connector. When in the up position, the two end caps face each other. To mate the connectors, the levers on both housings are squeezed, raising the end caps, and the two umbilicals are joined and twisted to couple them. Once the connectors are mated, the levers on both housings are released. This simultaneously seals both the umbilicals and the end caps. When dealing with cryogenic connectors, a purge can be applied to the housings to prevent icing when the connectors are demated.

Posted in: Briefs, Fluid Handling, Mechanical Components, Automation, Connectors and terminals, Connectors and terminals, Humidity, Particulate matter (PM), Seals and gaskets, Icing and ice detection

Systems, Methods, and Apparatus of a Low-Conductance Silicon Micro-Leak for Mass Spectrometer Inlet

Goddard Space Flight Center, Greenbelt, Maryland

Mass spectrometers on atmospheric entry probes require a method for introducing gas from high-pressure ambient regions to the vacuum of the mass spectrometer interior.

Posted in: Briefs, Mechanical Components, Automation, Spectroscopy, Spectroscopy, Gases, Valves, Test equipment and instrumentation

In-Situ Load System for Calibrating and Validating Aerodynamic Properties of Scaled Aircraft in Ground-Based Aerospace Testing Applications

This portfolio of technologies can be used in wind-tunnel force balance applications, and robotics applications such as rovers or prosthetic shoulder joints.

Langley Research Center, Hampton, Virginia

NASA’s Langley Research Center has developed three techniques and systems to calibrate and validate wind-tunnel force balances and other multi-component force transducers. The first is the Single Vector Calibration System (SVS), which uses a single deadweight for calibration and has been in active use at NASA for over 15 years. The second system is the In-Situ Load System (ILS). The ILS is based on the same fundamental concept as the SVS, but is designed for in-situ verification just prior to testing. Building off of the SVS and ILS, the third system is the Variable Acceleration Force Calibration System (VACS), which shares the single-vector force application concept, but generates those forces differently by keeping the mass constant and varying the acceleration. These techniques and systems provide for less complex and less labor-intensive calibration and verification of multi-component force transducers.

Posted in: Briefs, Mechanical Components, Automation, Calibration, Scale models, Wind tunnel tests, Aerodynamics

Release of a Stuck Solar Array or Antenna

Several options are examined that may also be useful in remotely controlled terrestrial environments.

Goddard Space Flight Center, Greenbelt, Maryland

Satellite launches experience approximately one deployment failure every two years. These failures include a solar array or antenna that fails to deploy because it is stuck due to a mechanism failure, or is snagged by a cable or thermal blanket. Knowledge of the exact circumstances of the deployable failure is limited. Ground commanding of the spacecraft is conducted in an attempt to free the stuck deployable.

Posted in: Briefs, Mechanical Components, Automation, Failure analysis, Antennas, Antennas, Robotics, Satellites

High-Heat-Flux-Capable Boundary Layer Vortex Generator and Boundary Layer Transition Device

Lyndon B. Johnson Space Center, Houston, Texas

Afixed geometry device has been developed to promote boundary layer transition and generation of streamwise vorticity, and is capable of withstanding entry heating environments for the Space Shuttle Orbiter. Designed to have a total height above the surface of the same order as the local boundary layer thickness, this device is approximately 0.25 in. (≈0.6 cm) tall and 4 in. (≈10 cm) long for the Orbiter entry application. Because temperature exposure is a key design factor for entry systems, the geometry has been optimized to establish peak heating rates and peak surface temperatures that are close to being spatially consistent on the protuberance. A relatively thin cross-section of 0.4 in. (≈1 cm) provides significant thermal radiation relief via conduction through the aft surface of the geometry. Sufficient mechanical strength to satisfy launch, ascent, entry, and landing conditions has been maintained in the design.

Posted in: Briefs, Mechanical Components, Automation, Thermal management, Thermal management, Aerodynamics, Entry, descent, and landing

GEMINI Stability Control for Reducing Pointing Jitter in CubeSats and Smallsats

Pointing jitter is significantly reduced by using two reaction wheels per axis, passive vibration isolators, and differential speed control.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Because of the cost-effectiveness of flying smallsats compared to large flagship spacecraft, there is increasing interest in boosting their capabilities for supporting precision science payloads and sophisticated instrumentation. Unfortunately, a major current drawback with using smallsats is their inability to hold the pointing line-of-sight steady without jittering. Line-of-sight jitter degrades observations made by cameras and other imaging-type instruments, and fundamentally limits the quality of science that can be obtained.

Posted in: Briefs, Mechanical Components, Automation, Stability control, Imaging, Imaging and visualization, Imaging, Imaging and visualization, Vibration, Vibration, Test equipment and instrumentation, Satellites

Piezoelectric-Actuated Rotary Ultrasonic Motor

This motor can be used where rotary actuation is required, particularly in cryogenic and high-temperature applications.

NASA’s Jet Propulsion Laboratory, Pasadena, California

This actuator was developed out of a need for a cryogenic actuator that can operate effectively in spite of the thermal mismatch involved with construction materials that have different expansion coefficients. Also, there is a need for a cryogenic motor that can drive infrared systems and produce minimal thermal energy that can interfere with their operation.

Posted in: Briefs, Mechanical Components, Mechanics, Automation, Sensors and actuators, Sensors and actuators, Thermal management, Thermal management, Materials properties

How to Prevent Step Losses with Stepper Motors

While stepper motors are an excellent solution for many applications, a key concern is step losses. However, in most instances step losses can be prevented or corrected. It is important to remember that a stepper motor does not operate like a DC motor. This white paper from MICROMO engineers provides guidance to determine step losses or non-operation across a variety of applications.

Posted in: White Papers, White Papers, Mechanical Components, Mechanics, Medical, Motion Control, Motors & Drives

Launch Tie-Down and Release Mechanism for CubeSat Spacecraft

This hardware configuration takes up an extremely small volume inside the CubeSat bus.

NASA’s Jet Propulsion Laboratory, Pasadena, California

As CubeSats take on increased functionality, including larger solar arrays for increased power demands and large antennas for science and communications needs, the requirements for launch tie-down and release mechanisms are evolving. In the past, some large CubeSat-deployable structures (solar arrays) relied on the confining walls of the CubeSat canister to act as the restraint mechanism. However, this practice is largely eliminated now, with most CubeSat specifications requiring a minimum amount of dwell time (after the CubeSat has been ejected from its parent canister) before the deployable structure can be released and deployed on orbit. Thus, a reliable restraint and release mechanism that does not depend on the geometry of the canister walls must be implemented.

Posted in: Briefs, Mechanical Components, Antennas, Antennas, Packaging, Launch vehicles, Satellites

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