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Miniature Robotic Spacecraft for Inspecting Other Spacecraft

A report discusses the Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam) — a compact robotic spacecraft intended to be released from a larger spacecraft for exterior visual inspection of the larger spacecraft. The Mini AERCam is a successor to the AERCam Sprint — a prior miniature robotic inspection spacecraft that was demonstrated in a space-shuttle flight experiment in 1997. The prototype of the Mini AERCam is a demonstration unit having approximately the form and function of a flight system. The Mini AERCam is approximately spherical with a diameter of about 7.5 in. (»19 cm) and a weight of about 10 lb (»4.5 kg), yet it has significant additional capabilities, relative to the 14-in. (36-cm), 35-lb (16-kg) AERCam Sprint. The Mini AERCam includes miniaturized avionics, instrumentation, communications, navigation, imaging, power, and propulsion subsystems, including two digital video cameras and a high-resolution still camera. The Mini AERCam is designed for either remote piloting or supervised autonomous operations, including station keeping and point-to-point maneuvering. The prototype has been tested on an air-bearing table and in a hardware-in-the-loop orbital simulation of the dynamics of maneuvering in proximity to the International Space Station.

Posted in: Briefs, TSP

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Solar Array Panels With Dust-Removal Capability

Inexpensive, low-power piezoelectric buzzers would be built in. It has been proposed to incorporate piezoelectric vibrational actuators into the structural supports of solar photovoltaic panels, for the purpose of occasionally inducing vibrations in the panels in order to loosen accumulated dust. Provided that the panels were tilted, the loosened dust would slide off under its own weight. Originally aimed at preventing obscuration of photovoltaic cells by dust accumulating in the Martian environment, the proposal may also offer an option for the design of solar photovoltaic panels for unattended operation at remote locations on Earth.

Posted in: Briefs, TSP

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NASA's Growing Commitment: The Space Garden

Astronauts cannot live on dehydrated ice cream alone. Like everyone else, they need their vegetables. Enter VEGGIE, the Deployable Vegetable System, currently under development by Orbital Technologies Corporation (ORBITEC). VEGGIE is the latest in a long line of vegetable production units ORBITEC is currently working on, with NASA assistance, to grow salad crops to supplement prepackaged foods during long stays in space.

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Blade-Pitch Control for Quieting Tilt-Rotor Aircraft

Actively induced harmonic blade-pitch oscillations reduce BVI noise. A method of reducing the noise generated by a tilt-rotor aircraft during descent involves active control of the blade pitch of the rotors. This method is related to prior such noise- reduction methods, of a type denoted generally as higher-harmonic control (HHC), in which the blade pitch is made to oscillate at a harmonic of the frequency of rotation of the rotor.

Posted in: Briefs, TSP

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Farm Equipment Manufacturer Shortens Design Cycle With Analysis Software

The design of new tilling machinery is accelerated using finite element analysis software. Humans have been using tools to make farming easier since the dawn of civilization. Since the turn of the 20th century, the growing use of mechanized power to till and sow fields has enabled farmers to realize incredible efficiency gains in the production of low-cost, safe, and nutritious foods and other crops, such as fibers. Today, bigger machines require less manpower to plant the crops that feed and clothe a swelling world population.

Posted in: Machinery & Automation, Briefs

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Attitude Control for a Solar-Sail Spacecraft

A report describes the personal radiation protection system (PRPS), which has been invented for use on the International Space Station and other spacecraft. The PRPS comprises walls that can be erected inside spacecraft, where and when needed, to reduce the amount of radiation to which personnel are exposed. The basic structural modules of the PRPS are pairs of 1-in. (2.54-cm)-thick plates of high-density polyethylene equipped with fasteners. The plates of each module are assembled with a lap joint. The modules are denoted bricks. A report discusses the attitude-control system of a proposed spacecraft that would derive at least part of its propulsion from a solar sail. The spacecraft would include a bus module containing three or more reaction wheels, a boom attached at one end to the bus module and attached at its other end to a two-degree-of-freedom (DOF) gimbal at the nominal center of mass of a sail module. Each DOF of the gimbal could be independently locked against rotation or allowed to rotate freely. By using the reaction wheels to rotate the bus when at least one gimbal DOF was in the free state, the center of mass (CM) of the spacecraft could be shifted relative to the center of pressure (CP) on the solar sail. The resulting offset between the CM and CP would result in a solar torque, which could be used to change the attitude of the spacecraft. The report discusses numerous aspects of the dynamics and kinematics of the spacecraft, along with the relationships between these aspects and the designs of such attitude-control-system components as sensors, motors, brakes, clutches, and gimbals.

Posted in: Briefs, TSP

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Nanoscale Materials Make for Large-Scale Applications

Since its dawning days, NASA has been at the forefront of developing and improving materials for aerospace applications. In particular, NASA requires dramatic advancements in material properties to enhance the performance, robustness, and reliability of its launch vehicles, spacecraft, and the International Space Station. Such advancements over the years include noise-abatement materials, fire-resistant fibers, heat-absorbing insulation, and light-but-strong moldable composites.

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