Mechanical & Fluid Systems

TLC is a computer program that determines corrections for radiotelescopepointing errors associated with tilts and elastic deformations. These errors occur because for rotation in azimuth, a radiotelescope is mounted on wheels that move on a circular track that deviates from perfect...

A report proposes the development of two different mechanisms that would prevent inadvertent startup of reactors in nuclear-fission-based propulsion and power systems in future spacecraft. The purpose of this development is to contribute to safety by ensuring that radioactivity is kept to...

Two reports summarize progress thus far in the continuing development of a spacecraft nuclear reactor, some or all of the fuel rods of which would not be loaded until the spacecraft was in orbit. (Keeping the fuel rods out of the reactor core before and during launch is intended to...

Structural dynamics are often an important consideration when evaluating system characteristics. A concern related to structural dynamics is the analysis of flutter for a flight vehicle. The instability associated with flutter can be quite sensitive to the structural dynamics; therefore, analysis of...

Improved designs have been conceived for lightweight tubes that can withstand the large (as much as 8 or 9 volume percent) freeze/thaw expansions and contractions of typical heat-transfer fluids like water and ammonia. Intended originally for radiators for rejecting waste heat from spacecraft, these...

A report describes an improved micromachined vaporizing-liquid microthruster (VLM), now under development as a prototype of thrusters for microspacecraft. This thruster is of the resistojet type: the energy for vaporization and expansion of a propellant liquid is provided through...

A report proposes a technique for onboard updating of the orbital period of an aerobraking spacecraft in order to estimate the time of the next periapsis. The time of periapsis is nearly centered in the middle of the drag pass, and provides a convenient reference time for events in the...

A report presents the mathematical basis of a method of controlling multiple spacecraft flying in formation, subject to control constraints. The spacecraft are assumed to be equipped with relative-position-sensing, relative-velocity-sensing, and communication infrastructure, and with...

A thermoelectric contact cooler/ freezer is designed to utilize thermal conduction to rapidly freeze blood and urine samples in test tubes and syringes. This apparatus is dependable, wastes little energy, contains no moving parts other than a fan, can operate in a wide temperature range and in any orientation...

A report proposes a miniature electrothermal spacecraft engine. The engine would include a chamber with an inside length of ≈1.5 cm and inside diameter of ≈0.25 cm, with a dielectric (ideally diamond) sidewall lining, a metal-coated expansion nozzle at one end, and a metal electrode at the other end. A...

A report describes an emerging class of miniature, highly capable, relatively inexpensive satellites that could be launched rapidly by nontraditional methods. Of particular interest is a subclass of proposed launch-on-demand microsatellites for inspecting and servicing other satellites (targets)...

A report describes the system for controlling the radial position and tilt of a spacecraftlike habitat for humans in NASA's Space Flight Environmental Simulator (SFES) — a 16-m-diameter centrifuge used previously to evaluate effects of hypergravitational acceleration on animals....

A report proposes the development of modular propulsion clusters (MPCs) — small, self-contained propulsion systems that would be standardized, mass-produced, and readily installed on a variety of miniature future spacecraft. The MPCs would be inexpensive, "turn-key" alternatives to expensive conventional...

A report presents a survey of the design engineering and scientific literature on airlocks and on planetary-exploration vehicles ("rovers"), from the perspective of evaluating existing and potential design concepts for airlocks for pressurized rovers. The airlocks are the key to designing a pressurized rover that...

A solar-powered vapor-compression refrigeration system developed for Johnson Space Center operates without batteries. The design of this system will make the cost of solar-powered refrigeration systems competitive and enable the use of such systems in long-distance spaceflights, military field...

The Advanced Life Support Automated Remote Manipulator (ALSARM) is a three-degree-of-freedom robotic system that positions an array of sensors inside a closed-system hydroponic chamber used in research on the production of biomass and the use of hydroponic subsystems of life-support...

Johnson Space Center has been leading the development of a high-power, electrothermal plasma rocket — the variable- specific-impulse magnetoplasma rocket (VASIMR) — that is capable of exhaust modulation at constant power. An electrodeless design enables the rocket to operate at power densities much...

A report describes Martian landing balls, which are under development for use in delivering scientific payloads to Mars. Martian landing balls are related to other soft-landing devices that resemble beach balls and that have been described in several previous NASA Tech Briefs articles. They are also related to the Zorb...