Tech Briefs

Software for Collaborative Use of Large Interactive Displays

The MERBoard Collaborative Workspace, which is currently being deployed to support the Mars Exploration Rover (MER) Missions, is the first instantiation of a new computing architecture designed to support collaborative and group computing using computing devices situated in NASA mission operations rooms. It is a software system for generation of large-screen interactive displays by multiple users. The architecture provides a platform and applications programming interface (API) for the development of collaborative applications for NASA mission operations. The standard deployment configuration provides an integrated whiteboard, Web browser, remote viewing and control for collaboration over distance, and personal and group storage spaces that provide ubiquitous access and sharing of data. Customization for specific domains is provided through plug-ins. For the MER mission, plug-ins include a flow-charting tool for strategic rover operations and mission planning, 3D visualization of the Martian terrain, a data navigator to navigate the mission database, and situational awareness tools. The MERBoard software is designed to run on large plasma displays with touch-screen overlays, thus providing an immersive and interactive environment for teams to view, annotate, and share data. The MERBoard overcomes the obstacles to communication, retention, and collaborative modification of information in diverse forms that can include text, data (including images) from scientific instruments, handwritten notes, hand drawings, and computer graphics. The MERBoard provides a unifying interface for the integration of heterogeneous applications, and provides those applications with a consistent model for saving and retrieving data. All applications may be viewed and controlled from any location that has a MERBoard. A personal client provides integration of a user’s personal computing environment with the MERBoard environment.

Posted in: Software, Briefs

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FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers

Advantages include tailorability of electronic properties and low power demands. A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, high-speed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits.

Posted in: Semiconductors & ICs, Briefs, TSP

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Theodolite Ring Lights

These lights facilitate the use of spherical tooling balls as position references. Theodolite ring lights have been invented to ease a difficulty encountered in the well-established opticalmetrology practice of using highly reflective spherical tooling balls as position references. As described in more detail below, a theodolite ring light is attached to a theodolite or telescope and used to generate a visible target on a tooling ball.

Posted in: Physical Sciences, Briefs

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Stable Satellite Orbits for Global Coverage of the Moon

A document proposes a constellation of spacecraft to be placed in orbit around the Moon to provide navigation and communication services with global coverage required for exploration of the Moon. There would be six spacecraft in inclined elliptical orbits: three in each of two orthogonal orbital planes, suggestive of a linked-chain configuration. The orbits have been chosen to (1) provide 99.999-percent global coverage for ten years and (2) to be stable under perturbation by Earth gravitation and solar-radiation pressure, so that no deterministic firing of thrusters would be needed to maintain the orbits. However, a minor amount of orbit control might be needed to correct for such unmodeled effects as outgassing of the spacecraft.

Posted in: Mechanical Components, Briefs

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On Release of Microbe-Laden Particles From Mars Landers

A paper presents a study in which rates of release of small particles from Mars lander spacecraft into the Martian atmosphere were estimated from first principles. Because such particles can consist of, or be laden with, terrestrial microbes, the study was undertaken to understand their potential for biological contamination of Mars. The study included taking account of forces and energies involved in adhesion of particles and of three mechanisms of dislodgement of particles from the surface of a Mars lander: wind shear, wind-driven impingement of suspended dust, and impingement of wind-driven local saltating sand particles. Wind shear was determined to be effective in dislodging only particles larger than about 10 microns and would probably be of limited interest because such large particles could be removed by preflight cleaning of the spacecraft and their number on the launched spacecraft would thus be relatively small. Dislodgement by wind-driven dust was found to be characterized by an adhesion half-life of the order of 10,000 years — judged to be too long to be of concern. Dislodgement by saltating sand particles, including skirts of dust devils, was found to be of potential importance, depending on the sizes of the spacecraft-attached particles and characteristics of both Mars sand-particle and spacecraft surfaces.

Posted in: Mechanical Components, Briefs, TSP

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Platform for Testing Robotic Vehicles on Simulated Terrain

Slope, ground material, and obstacles can be varied. The variable terrain tilt platform (VTTP) is a means of providing simulated terrain for mobility testing of engineering models of the Mars Exploration Rovers. The VTTP could also be used for testing the ability of other robotic land vehicles (and small vehicles in general) to move across terrain under diverse conditions of slope and surface texture, and in the presence of obstacles of various sizes and shapes.

Posted in: Mechanical Components, Briefs, TSP

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Low-Cost Propellant Launch From a Tethered Balloon

A document presents a concept for relatively inexpensive delivery of propellant to a large fuel depot in low orbit around the Earth, for use in rockets destined for higher orbits, the Moon, and for remote planets. The propellant is expected to be at least 85 percent of the mass needed in low Earth orbit to support the NASA Exploration Vision. The concept calls for the use of many small (≈10 ton) spin-stabilized, multistage, solid-fuel rockets to each deliver ≈250 kg of propellant. Each rocket would be winched up to a balloon tethered above most of the atmospheric mass (optimal altitude 26 ±2 km). There, the rocket would be aimed slightly above the horizon, spun, dropped, and fired at a time chosen so that the rocket would arrive in orbit near the depot. Small thrusters on the payload (powered, for example, by boil-off gasses from cryogenic propellants that make up the payload) would precess the spinning rocket, using data from a low-cost inertial sensor to correct for small aerodynamic and solid rocket nozzle misalignment torques on the spinning rocket; would manage the angle of attack and the final orbit insertion burn; and would be fired on command from the depot in response to observations of the trajectory of the payload so as to make small corrections to bring the payload into a rendezvous orbit and despin it for capture by the depot. The system is low-cost because the small rockets can be mass-produced using the same techniques as those to produce automobiles and low-cost munitions, and one or more can be launched from a U.S. territory on the equator (Baker or Jarvis Islands in the mid-Pacific) to the fuel depot on each orbit (every 90 minutes, e.g., any multiple of 6,000 per year).

Posted in: Mechanics, Mechanical Components, Briefs, TSP

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