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At least 307 records · Page 17

Optimizing Aerobot Exploration of Venus

Venus Flyer Robot (VFR) is an aerobot; an autonomous balloon probe designed for remote exploration of Earth's sister planet in 2003. VFR's simple navigation and control system permits travel to virtually any location on Venus, but it can survive for only a limited duration in the harsh Venusian environment. To help address this limitation, we develop: (1) a global circulation model that captures the most important characteristics of the Venusian atmosphere; (2) a simple aerobot model that captures thermal restrictions faced by VFR at Venus; and (3) one exact and two heuristic algorithms that, using abstractions (1) and (2), construct routes making the best use of VFR's limited lifetime. We demonstrate this modeling by planning several small example missions and a prototypical mission that explores numerous interesting sites recently documented in the plane tary geology literature.

SPACE EXPLORATION↗

High accuracy autonomous navigation using the global positioning system (GPS)

The application of global positioning system (GPS) technology to the improvement of the accuracy and economy of spacecraft navigation, is reported. High-accuracy autonomous navigation algorithms are currently being qualified in conjunction with the GPS attitude determination flyer (GADFLY) experiment for the small satellite technology initiative Lewis spacecraft. Preflight performance assessments indicated that these algorithms are able to provide a real time total position accuracy of better than 10 m and a velocity accuracy of better than 0.01 m/s, with selective availability at typical levels. It is expected that the position accuracy will be increased to 2 m if corrections are provided by the GPS wide area augmentation system.

Truong, Son H.↗

Relative navigation for spacecraft formation flying

The Goddard Space Flight Center Guidance, Navigation, and Control Center (GNCC) is currently developing and implementing advanced satellite systems to provide autonomous control of formation flyers. The initial formation maintenance capability will be flight-demonstrated on the Earth-Orbiter-1 (EO-1) satellite, which is planned under the National Aeronautics and Space Administration New Millennium Program to be a coflight with the Landsat-7 (L-7) satellite. Formation flying imposes relative navigation accuracy requirements in addition to the orbit accuracy requirements for the individual satellites. In the case of EO-1 and L-7, the two satellites are in nearly coplanar orbits, with a small difference in the longitude of the ascending node to compensate for the Earth's rotation. The GNCC has performed trajectory error analysis for the relative navigation of the EO-1/L-7 formation, as well as for a more advanced tracking configuration using cross-link satellite communications. This paper discusses the orbit determination and prediction accuracy achievable for EO-1 and L-7 under various tracking and orbit determination scenarios and discusses the expected relative separation errors in their formation flying configuration.

Hartman, Kate R.↗

Relative Navigation for Spacecraft Formation Flying

The Goddard Space Flight Center Guidance, Navigation, and Control Center (GNCC) is currently developing and implementing advanced satellite systems to provide autonomous control of formation flyers. The initial formation maintenance capability will be flight-demonstrated on the Earth-Orbiter-1 (EO-l) satellite, which is planned under the National Aeronautics and Space Administration New Millennium Program to be a coflight with the Landsat-7 (L-7) satellite. Formation flying imposes relative navigation accuracy requirements in addition to the orbit accuracy requirements for the individual satellites. In the case of EO-1 and L-7, the two satellites are in nearly coplanar orbits, with a small difference in the longitude of the ascending node to compensate for the Earth's rotation. The GNCC has performed trajectory error analysis for the relative navigation of the EO-1/L-7 formation, as well as for a more advanced tracking configuration using cross- link satellite communications. This paper discusses the orbit determination and prediction accuracy achievable for EO-1 and L-7 under various tracking and orbit determination scenarios and discusses the expected relative separation errors in their formation flying configuration.

Hartman, Kate R.↗

17th International Microgravity Measurements Group Meeting

The Seventeenth International Microgravity Measurements Group (MGMG) meeting was held 24-26 March 1998 at the Ohio Aerospace Institute (OAI) in Brook Park, Ohio. This meeting focused on the transition of microgravity science research from the Shuttle, Mir, and free flyers to the International Space Station. The MGMG series of meetings are conducted by the Principal Investigator Microgravity Services project of the Microgravity Science Division at the NASA Lewis Research Center. The MGMG meetings provide a forum for the exchange of information and ideas about the microgravity environment and microgravity acceleration research in the Microgravity Research Program. The meeting had participation from investigators in all areas of microgravity research. The attendees included representatives from: NASA centers; National Space Development Agency of Japan; European Space Agency; Daimler Benz Aerospace AG; Deutsches Zentrum fuer Luft- und Raumfahrt; Centre National d'Etudes Spatiales; Canadian Space Agency, national research institutions; Universities in U.S., Italy, Germany, and Russia; and commercial companies in the U.S. and Russia. Several agencies presented summaries of the measurement, analysis, and characterization of the microgravity environment of the Shuttle, Mir, and sounding rockets over the past fifteen years. This extensive effort has laid a foundation for pursuing a similar course during future microgravity science experiment operations on the ISS. Future activities of microgravity environment characterization were discussed by several agencies who plan to operate on the ISS.

DeLombard, Richard↗

Planning Experiments for a Microgravity Environment

Prior to performing science experiments in a microgravity environment, scientists must understand and appreciate a variety of issues related to that environment. The microgravity conditions required for optimum performance of the experiment will help define an appropriate carrier, drop facility, sounding rocket, free-flyer, or manned orbiting spacecraft. Within a given carrier, such as the International Space Station, experiment sensitivity to vibrations and quasi-steady accelerations should also influence the location and orientation of the experiment apparatus; the flight attitude of the carrier (if selectable); and the scheduling of experiment operations in conjunction with other activities. If acceptable microgravity conditions are not expected from available carriers or experiment scheduling cannot avoid disruptive activities, then a vibration isolation system should be considered. In order to best interpret the experimental results, appropriate accelerometer data must be collected contemporaneously with the experimental data. All of this requires a good understanding of experiment sensitivity to the microgravity environment.

Rogers, Melissa J. B.↗

Practice Oriented Master's in Optics

The development of an interdisciplinary Masters Program with a concentration in Optics and Photonics Technology has been is described. This program was developed under the U.S. Manufacturing Education and Training Activity of the Technology Reinvestment Project. This development was a collaboration between the University of Alabama in Huntsville (UAH), Alabama A&M University, Northwest Shoals Community College, the NASA Marshall Space Flight Center (MSFC), the U.S. Army Missile Command, Oak Ridge National Laboratory (ORNL), Advanced Optical Systems Inc., Dynetics, Inc., Hughes Danbury Optical Systems, Inc., Nichols Research and Speedring Inc. These organizations as well as the National Institute for Standards and Technology and SCI, Inc. have been participating fully in the design, development and implementation of this program. This goal of the program is to produce highly trained graduates who can also solve practical problems. To this end, the program includes an on-site practicum at a manufacturing location. The broad curriculum of this program emphasizes the fundamentals of optics, optical systems manufacturing and testing, and the principles of design and manufacturing to cost for commercial products. The Master's of Science (MS) in Physics and Master's of Science in Engineering (MSE) in Electrical Engineering Degrees with concentration in Optics and Photonics Technology are offered by the respective UAH academic departments with support from and in consultation with a Steering Committee composed of representatives from each of the participating organizations, and a student representative from UAH. The origins of the programs are described. The curricula of the programs is described. The course outlines of the new courses which were developed for the new curriculum are included. Also included are samples of on-site practicums which the students have been involved in. Also included as attachments are samples of the advertisements, which includes flyers, and the program description given to prospective students. The expenditures in the development and information about the cost sharing among the participating organizations is also included. Finally a listing membership of the steering committee is attached.

Dimmock, John O.↗

STS-95 Post Flight Presentation

The STS-95 flight crew, Cmdr. Curtis L. Brown, Pilot Steven W. Lindsey, Mission Specialists Scott E. Parazynski, Stephen K. Robinson, and Pedro Duque, and Payload Specialists Chiaki Mukai and John H. Glenn present a video mission over-view of their space flight. Images include prelaunch activities such as eating the traditional breakfast, crew suit-up, and the ride out to the launch pad. Also, included are various panoramic views of the shuttle on the pad. The crew can be seen being readied in the "whiteroom" for their mission. After the closing of the hatch and arm retraction, launch activities are shown including countdown, engine ignition, launch, and the separation of the Solid Rocket Boosters. The primary objectives, which include the conducting of a variety of science experiments in the pressurized SPACEHAB module, the deployment and retrieval of the Spartan free-flyer payload, and operations with the HST Orbiting Systems Test (HOST) and the International Extreme Ultraviolet Hitchhiker (IEH) payloads are discussed in both the video and still photo presentation.

Source record↗

STS-95 Mission Highlights Resources Tape

The STS-95 flight crew, Commander Curtis L. Brown, Pilot Steven W. Lindsey, Mission Specialists Scott E. Parazynski, Stephen K. Robinson, and Pedro Duque, and Payload Specialists Chiaki Mukai and John H. Glenn present a video overview of their space flight. They are seen performing pre-launch activities such as eating the traditional breakfast, crew suit-up, and the ride out to the launch pad. Also, included are various panoramic views of the shuttle on the pad. The crew is readied in the 'white room' for their mission. After the closing of the hatch and arm retraction, launch activities are shown including countdown, engine ignition, launch, and the separation of the Solid Rocket Boosters. Once on-orbit the primary objectives include conducting a variety of science experiments in the pressurized SPACEHAB module, the deployment and retrieval of the Spartan free-flyer payload, and operations with the Hubble Space Telescope (HST) Orbiting Systems Test (HOST) and the International Extreme Ultraviolet Hitchhiker (IEH) payloads being carried in the payload bay. Throughout the presentation, the astronauts take turns narrating particular aspects of the mission with which they were involved.

Source record↗

Medical Operation KC-135 Familiarization Flight

As new personnel join the Medical Operations Branch, it is critical that they understand the effects of microgravity on medical procedures, hardware, and supplies. The familiarization flight provided new personnel with a better understanding of the effects of microgravity on (1) medical procedures, (2) patient and rescuer restraint, (3) medical fluids, and (4) medical training for space flight. The flight process also provided experience in flight proposal preparation, flight test plan preparation and execution, and final report preparation. In addition, first time flyers gained insight on their performance level in microgravity for future flights.

Dawson, Chris↗

Video Based Sensor for Tracking 3-Dimensional Targets

Video-Based Sensor for Tracking 3-Dimensional Targets The National Aeronautics and Space Administration's (NASAs) Marshall Space Flight Center (MSFC) has been developing and testing video-based sensors for automated spacecraft guidance for several years, and the next generation of video sensor will have tracking rates up to 100 Hz and will be able to track multiple reflectors and targets. The Video Guidance Sensor (VGS) developed over the past several years has performed well in testing and met the objective of being used as the terminal guidance sensor for an automated rendezvous and capture system. The first VGS was successfully tested in closed-loop 3-degree-of-freedom (3- DOF) tests in 1989 and then in 6-DOF open-loop tests in 1992 and closed-loop tests in 1993-4. Development and testing continued, and in 1995 approval was given to test the VGS in an experiment on the Space Shuttle. The VGS flew in 1997 and in 1998, performing well for both flights. During the development and testing before, during, and after the flight experiments, numerous areas for improvement were found. The VGS was developed with a sensor head and an electronics box, connected by cables. The VGS was used in conjunction with a target that had wavelength-filtered retro-reflectors in a specific pattern, The sensor head contained the laser diodes, video camera, and heaters and coolers. The electronics box contained a frame grabber, image processor, the electronics to control the components in the sensor head, the communications electronics, and the power supply. The system works by sequentially firing two different wavelengths of laser diodes at the target and processing the two images. Since the target only reflects one wavelength, it shows up well in one image and not at all in the other. Because the target's dimensions are known, the relative positions and attitudes of the target and the sensor can be computed from the spots reflected from the target. The system was designed to work from I meter out to I 10 meters. The VGS was mounted on the Space Shuttle while its target was mounted on the Spartan free-flyer carried on the same Shuttle flight. The VGS tracked the Spartan at ranges up to 170m, and the VGS range data very closely matched the range data from the Hand-Held Laser- Rangefinder used by the astronauts on board the Shuttle. While the VGS was designed primarily as a terminal guidance sensor for an automated spacecraft, it could be applied to other uses. It could be used as an alignment aid for an operator of a remote system (giving position and attitude feedback data, as well as a camera view of the target), as a feedback system for a robotic arm, or for automated vehicle guidance. The next generation VGS, with its higher tracking rates, smaller size, and lower power could be used in more places than the original VGS, and by using LED's instead of laser diodes, the system would be eye-safe at any range. Other possible uses include tracking 3-dimensional objects with retro-reflectors mounted at various locations or motion analysis by placing several retro-reflectors on the moving object and tracking them at high speeds. There are few sensors capable of performing tasks similar to those the VGS can perform, and the next generation VGS will be even more capable than the original. Some of this work is previously presented in the papers.

Howard, R. T.↗

Autonomous Relative Navigation for Formation-Flying Satellites Using GPS

The Goddard Space Flight Center is currently developing advanced spacecraft systems to provide autonomous navigation and control of formation flyers. This paper discusses autonomous relative navigation performance for a formation of four eccentric, medium-altitude Earth-orbiting satellites using Global Positioning System (GPS) Standard Positioning Service (SPS) and "GPS-like " intersatellite measurements. The performance of several candidate relative navigation approaches is evaluated. These analyses indicate that an autonomous relative navigation position accuracy of 1meter root-mean-square can be achieved by differencing high-accuracy filtered solutions if only measurements from common GPS space vehicles are used in the independently estimated solutions.

Gramling, Cheryl↗

NASA Master Teacher Re-Certification Program

Edward Waters College is submitting a final report covering the grant period from January 1999 - April 30, 2000. The Teacher re-certification program at Edward Waters College created a high quality professional development opportunity for middle and high school science teachers which will contribute to the improvement of science education and the use of innovation technologies in the classroom for years to come. The following goals and objectives were met and exceeded during the grant period. 1) A focused and relevant educational technology curriculum based on National Science Education Standard and state-of-the art educational resources that are accepted as one of the qualifications for re-certification in the scientific discipline in Duval County, Florida. 2) The program goal was to recertify 40 middle and high school science teachers over a two- year period. This goal was met and exceeded the projected number by recertifying over 80 middle and high school science and math teachers over a two-year period. 3) Teachers that were recertified were given an opportunity to public information that they developed on EWC's Web page or develop a web page of their own. Area schools were made aware of this information through various forms of communication with the teachers in Duval County School District, i.e., flyers sent from EWC to participants, school newspapers, word of mouth, etc. 4) A multimedia technology resource lab is available at EWC for use as a "Learning Lab" for class field trips by Duval County teachers.

Okari-Brooks, Emma↗

Free-Flying Magnetometer Data System

The Free-Flying Magnetometer (FFM) is an autonomous "sensorcraft" developed at the Jet Propulsion Laboratory (JPL) for the Enstrophy sounding rocket mission. This mission was a collaborative project between the University of New Hampshire, Cornell University and JPL. The science goal of the mission was the study of current filamentation phenomena in the northern auroral region through multipoint measurements of magnetic field. The technical objective of the mission was the proof of concept of the JPL FFM design and the demonstration of an in-situ multipoint measurement technique employing many free-flying spacecraft. Four FFMs were successfully deployed from a sounding rocket launched from Poker Flats, Alaska on February 11, 1999. These hockey-puck-sized (80 mm diameter, 38 mm. height, 250 gram mass) free flyers each carry a miniature 3-axis flux-gate magnetometer that output +/- 2 V signals corresponding to a +/- 60,000 nT measurement range for each axis. The FFM uses a synchronized four-channel Sigma(Delta) Analog-to-Digital Converter (ADC) having a dynamic range of +/- 2.5V and converting at a rate of 279 samples/second/channel. Three channels are used to digitize the magnetometer signals to 17-bit (1.144 nT/bit) resolution. The fourth ADC channel is multiplexed for system monitoring of four temperature sensors and two battery voltages. The FFM also contains two sun sensors, a laser diode which emits a fan-shaped beam, a miniature S-band transmitter for direct communication to the ground station antennas, an ultra-stable Temperature Compensated Crystal Oscillator (TCXO) clock, an integrated data subsystem implemented in a Field-Programmable Gate Array (FPGA), a 4 Mbit Static Random Access Memory (SRAM) for data storage and Lithium Thionyl Chloride batteries for power. Communicating commands to the FFM prior to deployment is achieved with an infrared (IR) link. The FFM IR receiver responds to 9-bit pulse coded signals that are generated by an IR Light Emitting Diode (LED) in the payload for turning FFM power on or off and placing the FFM in a test mode or flight mode. The IR links are also used to synchronize (zero) the clocks onboard all the FFMs through a reset pulse originating from the payload GPS receiver that is issued when the FFMs are in flight mode. The FPGA based data subsystem manages continuous data collection from the four ADC channels and sun sensors, formatting and storing the data to SRAM, and controlling downlink transmission. The transmitter is powered only after a 2547 frame SRAM buffer has been filled (approx. 5 minutes of data). The data is Viterbi encoded and sent to the S-band transmitter via a First-In-First-Out (FIFO) buffer who's output is clocked at 100 bits/second. After the 26-second transmission, the transmitter is turned off to reduce noise coupling to the sensitive magnetometer. The data subsystem control consists of a master state machine that performs data flow management and is interfaced through a prioritized interrupt scheme to state machines that service the ADC, sun sensors and transmitter FIFO. Continuous data collection prevents the missing of data during transmission and provides implicit time tagging of the data acquired by the ADC because of synchronization with the TCXO clock.

Blaes, B.↗

The NASA ASTP Combined-Cycle Propulsion Database Project

The National Aeronautics and Space Administration (NASA) communicated its long-term R&D goals for aeronautics and space transportation technologies in its 1997-98 annual progress report (Reference 1). Under "Pillar 3, Goal 9" a 25-year-horizon set of objectives has been stated for the Generation 3 Reusable Launch Vehicle ("Gen 3 RLV") class of space transportation systems. An initiative referred to as "Spaceliner 100" is being conducted to identify technology roadmaps in support of these objectives. Responsibility for running "Spaceliner 100" technology development and demonstration activities have been assigned to NASA's agency-wide Advanced Space Transportation Program (ASTP) office located at the Marshall Space Flight Center. A key technology area in which advances will be required in order to meet these objectives is propulsion. In 1996, in order to expand their focus beyond "allrocket" propulsion systems and technologies (see Appendix A for further discussion), ASTP initiated technology development and demonstration work on combined-cycle airbreathing/rocket propulsion systems (ARTT Contracts NAS8-40890 through 40894). Combined-cycle propulsion (CCP) activities (see Appendix B for definitions) have been pursued in the U.S. for over four decades, resulting in a large documented knowledge base on this subject (see Reference 2). In the fall of 1999 the Combined-Cycle Propulsion Database (CCPD) project was established with the primary purpose of collecting and consolidating CCP related technical information in support of the ASTP's ongoing technology development and demonstration program. Science Applications International Corporation (SAIC) was selected to perform the initial development of the Database under its existing support contract with MSFC (Contract NAS8-99060) because of the company's unique combination of capabilities in database development, information technology (IT) and CCP knowledge. The CCPD is summarized in the descriptive 2-page flyer appended to this paper as Appendix C. The purpose of this paper is to provide the reader with an understanding of the objectives of the CCPD and relate the progress that has been made toward meeting those objectives.

Hyde, Eric H.↗

Planned Axial Reorientation Investigation on Sloshsat

This paper details the design and logic of an experimental investigation to study axial reorientation in low gravity. The Sloshsat free-flyer is described. The planned axial reorientation experiments and test matrixes are presented. Existing analytical tools are discussed. Estimates for settling range from 64 to 1127 seconds. The planned experiments are modelled using computational fluid dynamics. These models show promise in reducing settling estimates and demonstrate the ability of pulsed high thrust settling to emulate lower thrust continuous firing.

Chato, David J.↗

Models for Liquid Impact Onboard Sloshsat FLEVO

Orbital experiments on the behavior of liquid in spacecraft are planned. The Sloshsat free-flyer is described. Preparation of the experiments, and later evaluation, are supported by models of varying complexity. The characteristics of the models are discussed. Particular attention is given to the momentum transfer between the liquid and the spacecraft, in connection with the liquid impact that may occur at the end of a reorientation maneuver of the spacecraft.

Vreeburg, Jan P. B.↗

The Infrared Telescope in Space Mission

The NASA/Japanese Space Agency Infrared Telescope in Space (IRTS) mission was one of seven experiments on the first Space Flyer Unit (SFU-1). This satellite was launched on a Japanese H-2 expendable launch vehicle from Tanegashima Space Center on March 18, 1995 and was retrieved by the NASA space shuttle the following January for refurbishment and reuse. The IRTS itself consisted of a super-fluid liquid helium-cooled telescope with four infrared focal plane science instruments that operated simultaneously. During its one-month lifetime before the liquid helium was exhausted the IRTS mapped 7% of the sky. These data are now being released to the general astronomical community through IPAC at the California Institute of Technology.

Roellig, Thomas L.↗