Sample records for tumble rates rendezvousing

  1. Optical Survey of the Tumble Rates of Retired GEO Satellites

    NASA Astrophysics Data System (ADS)

    Binz, C.; Davis, M.; Kelm, B.; Moore, C.

    2014-09-01

    The Naval Research Lab (NRL) and the Defense Advanced Research Projects Agency (DARPA) have made significant progress toward robotic rendezvous and docking between spacecraft, however the long-term attitude motion evolution of uncontrolled resident space objects has never been well-characterized. This effort set out to identify the motion exhibited in retired satellites at or near geosynchronous orbit (GEO). Through analysis of the periodic structure of observed reflected light curves, estimated tumble rates were determined for several retired satellites, typically in a super-GEO disposal orbit. The NRL's 1-meter telescope at Midway Research Center was used to track and observe the objects while the sun-satellite-observer geometry was most favorable; typically over a one- to two-hour period, repeated multiple times over the course of weeks. By processing each image with calibration exposures, the relative apparent magnitude of the brightness of the object over time was determined. Several tools, including software developed internally, were used for frequency analysis of the brightness curves. Results show that observed satellites generally exhibit a tumble rate well below the notional bounding case of one degree per second. When harmonics are found to exist in the data, modeling and simulation of the optical characteristics of the satellite can help to resolve ambiguities. This process was validated on spacecraft for which an attitude history is known, and agreement was found.

  2. Angular velocity tracking for satellite rendezvous and docking

    Microsoft Academic Search

    Jianxun Liang; Ou Ma

    2011-01-01

    Autonomous satellite on-orbit servicing is a very challenging task when the satellite to be serviced is tumbling and has an unknown dynamics model. This paper addresses an adaptive control approach, which can be used to assist the control of a servicing satellite to rendezvous and dock with a tumbling satellite whose dynamics model is unknown. A proximity-rendezvous and docking operation

  3. Angular-velocity tracking with unknown dynamics for satellite rendezvous and docking

    Microsoft Academic Search

    Xiumin Diao; Jianxun Liang; Ou Ma

    2009-01-01

    Autonomous satellite on-orbit servicing is a very challenging task when the satellite to be serviced is tumbling and has an unknown dynamics model. This paper addresses an adaptive control approach which can be used to assist the control of a servicing satellite to rendezvous and dock with a tumbling satellite whose dynamics model is unknown. A proximity-rendezvous and docking operation

  4. Asteroid Rendezvous

    NASA Astrophysics Data System (ADS)

    Bell, Jim; Mitton, Jacqueline

    2002-08-01

    Foreword C. Shoemaker; 1. Eros and the asteroids J. Veverka; 2. A date with Eros R. Farquhar; 3. From launch to rendezvous S. Murchie; 4. Landscape of an asteroid L. Prockter and M. Robinson; 5. Form and substance P. Thomas and M. Zuber; 6. Ingredients of an asteroid J. Bell; 7. Shaped by history C. Chapman; 8. On course and picture perfect M. Bell and B. Owen; 9. Mission accomplished A. Cheng.

  5. Tumbling cards L. Mahadevan

    E-print Network

    Mahadevan, L.

    -on and slows down. If the inertial forces are large enough, the card continues past the broadside-on position vertical to horizontal and slow in the opposite case, there is also a net horizontal force on the card to the ground, periodi- cally oscillating from side to side, or tumble while drifting steadily to one side

  6. Wookie Rendezvous

    E-print Network

    Multiple Contributors

    1999-01-01

    of this zine or anyof its contents without the written permission of the editor, artists andauthors. All rights revert to originator upon publication. Wookiee Rendezvous ARTWORK Front Cover: "Local Hero" Dianne Smith Title Page: Nicola Pearce Han & Leia... Alia Solo's Bedside Manner 5 Han Judy Street EyesofaJedi 8 Boba Fett Alia EyesofaJedi 13 Luke Sandi Jones Eyes ofa Jedi 19 Han Alia First Impressions 29 Han Cheree Cargill Han's Kid 34 Han & Leia Judy Street - Han's Kid 47 Vader Z.P. Florian A...

  7. Optimal Rendezvous Path Planning to an Uncontrolled Tumbling Target

    E-print Network

    Dettweiler, Michael

    .chudej@uni-bayreuth.de). Abstract: As the number of uncontrollable objects in low earth orbit is rising, the thread of collisions the first artificial earth satellite Sputnik was launched in 1957, the number of earth surrounding ob- jects is increasing continuously. As a consequence of more satellites being brought into orbit without removing old

  8. QUENCHING TUMBLING MILL TUMBLES CASTINGS OVER EACH OTHER TO REMOVE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    QUENCHING TUMBLING MILL TUMBLES CASTINGS OVER EACH OTHER TO REMOVE RUNNERS AND SPRUES WHILE QUICKLY COOLING THEM WITH WATER IN THE MALLEABLE ANNEALING BUILDING. THIS PROCESS ENSURES CASTINGS FORM WHITE IRON PRIOR TO BEING ASSEMBLED. - Stockham Pipe & Fittings Company, Malleable Annealing Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  9. Rough and Tumble Play 101

    ERIC Educational Resources Information Center

    Carlson, Frances

    2009-01-01

    Many people fear that play-fighting or rough and tumble play is the same as real fighting. There is also a fear that this rough play will become real fighting if allowed to continue. Most of all, parents and teachers fear that during the course of rough and tumble play a child may be hurt. To provide for and allow children to play rough without…

  10. Space Shuttle Orbiter onboard rendezvous navigation

    NASA Astrophysics Data System (ADS)

    Little, M. J.

    Much of the work that the Space Shuttle will perform requires a capability to rendezvous with other orbiting objects. The formulation and design philosophy behind the Space Shuttle Orbiter rendezvous navigation system are the subjects of this paper. The current rendezvous navigation design incorporates a Kalman filter to estimate the relative position and velocity. The filter is augmented with state elements for the estimation of colored measurement noise and acceleration modeling errors. Several measurement types are available to the filter: a manual optical sighting device, an automatic optical tracking instrument, and a rendezvous radar which provides range and range rate measurements as well as the line of sight direction. The filter also includes a technique for detecting highly improbable measurements and excluding them from Kalman processing.

  11. Space Shuttle Orbiter onboard rendezvous navigation

    NASA Technical Reports Server (NTRS)

    Little, M. J.

    1982-01-01

    Much of the work that the Space Shuttle will perform requires a capability to rendezvous with other orbiting objects. The formulation and design philosophy behind the Space Shuttle Orbiter rendezvous navigation system are the subjects of this paper. The current rendezvous navigation design incorporates a Kalman filter to estimate the relative position and velocity. The filter is augmented with state elements for the estimation of colored measurement noise and acceleration modeling errors. Several measurement types are available to the filter: a manual optical sighting device, an automatic optical tracking instrument, and a rendezvous radar which provides range and range rate measurements as well as the line of sight direction. The filter also includes a technique for detecting highly improbable measurements and excluding them from Kalman processing.

  12. Comet rendezvous mission study

    NASA Technical Reports Server (NTRS)

    Friedlander, A. L.; Wells, W. C.

    1971-01-01

    Four periodic comets with perihelia between 1980 and 1986 (Encke, d'Arrest, Kipff, and Halley) are used as candidates for the comet rendezvous mission study. All these comet apparitions are especially favorable for rendezvous missions, because of early earth-based comet recovery, good opportunities to view their activity from earth, and reasonable launch vehicle and trajectory requirements for nominal payloads.

  13. CTV rendezvous techniques

    NASA Astrophysics Data System (ADS)

    Jennings, Jerry L.; Anderson, Robert L.

    The cargo transfer vehicle (CTV) requires the capability to perform automated rendezvous with Space Station Freedom (SSF) using onboard sensors and algorithms. The current approach to CTV rendezvous applies techniques developed during the orbital maneuvering vehicle (OMV) program which have been mechanized for automatic, onboard execution. The initial catch up sequence can be described as a passive rendezvous without explicit time of arrival control. The ultimate requirement for this rendezvous technique is to place the CTV on the SSF V-bar axis at some specified downrange distance. The launch vehicle will use yaw steering during orbit injection to achieve the proper phantom plane for nodal biasing. This presentation describes the primary components of the CTV rendezvous scheme.

  14. Tumbling of a rigid rod in a shear flow

    NASA Astrophysics Data System (ADS)

    van Leeuwen, J. M. J.; Blöte, H. W. J.

    2014-09-01

    The tumbling of a rigid rod in a shear flow is analyzed in the high viscosity limit. Following Burgers, the Master Equation is derived for the probability distribution of the orientation of the rod. The equation contains one dimensionless number, the Weissenberg number, which is the ratio of the shear rate and the orientational diffusion constant. The equation is solved for the stationary state distribution for arbitrary Weissenberg numbers, in particular for the limit of high Weissenberg numbers. The stationary state gives an interesting flow pattern for the orientation of the rod, showing the interplay between flow due to the driving shear force and diffusion due to the random thermal forces of the fluid. The average tumbling time and tumbling frequency is calculated as a function of the Weissenberg number. A simple crossover function is proposed which covers the whole regime from small to large Weissenberg numbers.

  15. Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Rendezvous Docking Simulator. The simulation demonstrated linear and gimbal motions of the capsule and a Gemini-Agena docking. [Entire movie available on DVD from CASI as Doc ID 20070030983. Contact help@sti.nasa.gov

  16. Comet rendezvous mission

    Microsoft Academic Search

    Tony Reichhardt

    1984-01-01

    A National Aeronautics and Space Administration (NASA) advisory team has selected a bright, short-period comet named Kopff as the target for a comet rendezvous\\/asteroid flyby mission to be launched in 1990. The rendezvous is the third in a series of ``core missions''-along with the Venus Radar Mapper and a Mars orbiter---to be proposed following recommendations by the agency's Solar System

  17. Calculation of tumbling boundaries of a generic wing-only airliner

    NASA Astrophysics Data System (ADS)

    Khrabrov, A.; Sidoryuk, M.

    2015-06-01

    The aerodynamic model of a generic wing-only airliner configuration is developed for a whole range of angles of attack (-180°. . . +180°), based on experimental data obtained in wind tunnels using static, and forced oscillations. Two different approaches for the tumbling boundaries calculation are used. In the first approach, the steady pitch autorotation is calculated. In the second approach, for various angles of attack, the minimum pitch rate disturbance is considered which can result in tumbling. The tumbling boundaries are calculated via the use of a continuation technique. The dependence of these boundaries on such parameters as flight altitude, aircraft center of gravity position, and total velocity is analyzed.

  18. The tumbling spin state of (99942) Apophis

    NASA Astrophysics Data System (ADS)

    Pravec, P.; Scheirich, P.; ?urech, J.; Pollock, J.; Kušnirák, P.; Hornoch, K.; Galád, A.; Vokrouhlický, D.; Harris, A. W.; Jehin, E.; Manfroid, J.; Opitom, C.; Gillon, M.; Colas, F.; Oey, J.; Vraštil, J.; Reichart, D.; Ivarsen, K.; Haislip, J.; LaCluyze, A.

    2014-05-01

    Our photometric observations of Asteroid (99942) Apophis from December 2012 to April 2013 revealed it to be in a state of non-principal axis rotation (tumbling). We constructed its spin and shape model and found that it is in a moderately excited Short Axis Mode (SAM) state with a ratio of the rotational kinetic energy to the basic spin state energy E/E0=1.024±0.013. (All quoted uncertainties correspond to 3?.) The greatest and intermediate principal moments of inertia are nearly the same with I2/I3=0.965-0.015+0.009, but the smallest principal moment of inertia is substantially lower with I1/I3=0.61-0.08+0.11; the asteroid’s dynamically equivalent ellipsoid is close to a prolate ellipsoid. The precession and rotation periods are P?=27.38±0.07 h and P?=263±6 h, respectively; the strongest observed lightcurve amplitude for the SAM case is in the 2nd harmonic of P1=P=30.56±0.01 h. The rotation is retrograde with the angular momentum vector’s ecliptic longitude and latitude of 250° and -75° (the uncertainty area is approximately an ellipse with the major and minor semiaxes of 27° and 14°, respectively). An implication of the retrograde rotation is a somewhat increased probability of the Apophis’ impact in 2068, but it is still very small with the risk level on the Palermo Scale remaining well below zero. Apophis is a member of the population of slowly tumbling asteroids. Applying the theory of asteroid nutational damping by Breiter et al. (Breiter, S., Ro?ek, A., Vokrouhlický, D. [2012]. Mon. Not. R. Astron. Soc. 427, 755-769), we found that slowly tumbling asteroids predominate in the spin rate-size range where their estimated damping times are greater than about 0.2 Gyr. The appearance that the PA/NPA rotators transition line seems to follow a line of constant damping time may be because there are two or more asteroid spin evolution mechanisms in play, or the factor of ?Q (the elastic modulus times the quality factor) is not constant but it may decrease with decreasing asteroid size, which would oppose the trend due to decreasing collisional age or excitation time.

  19. An extension of generalized Taylor dispersion in unbounded homogeneous shear flows to run-and-tumble chemotactic bacteria

    E-print Network

    Bearon, Rachel

    -and-tumble chemotactic bacteria R. N. Bearon School of Oceanography, Box 357940, University of Washington, Seattle of flow, the biased random walk of bacteria such as Escherichia coli is modeled by straight runs. In the well-studied situation of weak bias in tumble rate, bacteria disperse over a diffusive time scale

  20. Use of a laser navigation sensor for automatic rendezvous

    NASA Astrophysics Data System (ADS)

    Kachmar, Peter M.; Chu, William; Polutchko, Robert J.

    New mission requirements for earth, lunar, and Mars space programs require the development of an automatic rendezvous and docking system capability. Paramount to the development of this system is the capability to provide precise relative state knowledge in position, velocity, attitude, and attitude rate between the target and chaser vehicles. Use of a laser sensor in combination with an appropriately configured navigation filter can provide the desired navigation accuracy. This paper explores the filter configuration, design considerations, and subsequent performance of a laser sensor applied to an autonomous rendezvous and docking system. Shuttle rendezvous and docking are used to demonstrate the generic navigation system concepts.

  1. Rendezvous and docking

    Microsoft Academic Search

    W. David Woods

    \\u000a Getting off the Moon and returning to the relative safety of the command module was a feat that literally defined the mission\\u000a plan. NASA even named it lunar orbit rendezvous (LOR) in view of the important benefits the technique promised in overall weight savings, including that of the launch vehicle.\\u000a Yet, to many in NASA in the early 1960s, it

  2. Rendezvous BET Program

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1986-01-01

    Computes relative positions of two vehicles in concentric orbits. LRBET3 program best-estimate-of-trajectory (BET) calculation for postflight trajectory analysis of Shuttle orbital rendezvous maneuvers. LRBET3 produces estimated measurements for reconstructing relative positions of two vehicles. Kalman filter and smoothing filter applied to relative measurement input data to estimate state vector, reduce noise, and produce BET output. BET calculation minimizes variances of all trajectory estimation errors. LRBET3 written in FORTRAN IV for batch execution.

  3. Rendezvous radar for orbital vehicles

    Microsoft Academic Search

    John W. Locke; Larry D. Casey

    1992-01-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of

  4. Cooperative control of UAV rendezvous

    Microsoft Academic Search

    T. W. McLain; Phillip R. Chandler; Steven Rasmussen; Meir Pachter

    2001-01-01

    The cooperative control of timing and synchronization of tasks of multiple unmanned air vehicles (UAVs) represents a valuable capability for a wide range of potential multi-UAV missions. This research addresses the specific problem of cooperative rendezvous in which multiple UAVs are to arrive at their targets simultaneously. The development of a rendezvous manager state machine and a cooperative control decomposition

  5. Rendezvous and docking tracker

    NASA Technical Reports Server (NTRS)

    Ray, Art J.; Ross, Susan E.; Deming, Douglas R.

    1986-01-01

    A conceptual solid-state rendezvous and docking tracker (RDT) has been devised for generating range and attitude data for a docking vehicle relative to a target vehicle. Emphasis is placed on the approach of the Orbiter to a link with the Space Station. Three laser illuminators ring the optical axis of the lens a directed toward retroreflectors on the target vehicle. Each retroreflector is equipped with a bandpass filter for a designated illumination frequency. Data are collected sequentially over a 20 deg field of view as the range closes to 100-1000 m. A fourth ranging retroreflector 0.3 m from center is employed during close-in maneuvers. The system provides tracking data on motions with 6 deg of freedom, and furnishes 500 msec updates (to be enhanced to 100 msec) to the operator at a computer console.

  6. Rendezvous radar for orbital vehicles

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Casey, Larry D.

    1992-03-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of hi-rel electronics hardware for space is discussed.

  7. Near Earth asteroid rendezvous

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Spacecraft Design Course is the capstone design class for the M.S. in astronautics at the Naval Postgraduate School. The Fall 92 class designed a spacecraft for the Near Earth Asteroid Rendezvous Mission (NEAR). The NEAR mission uses a robotic spacecraft to conduct up-close reconnaissance of a near-earth asteroid. Such a mission will provide information on Solar System formation and possible space resources. The spacecraft is intended to complete a NEAR mission as a relatively low-budget program while striving to gather as much information about the target asteroid as possible. A complete mission analysis and detailed spacecraft design were completed. Mission analysis includes orbit comparison and selection, payload and telemetry requirements, spacecraft configuration, and launch vehicle selection. Spacecraft design includes all major subsystems: structure, electrical power, attitude control, propulsion, payload integration, and thermal control. The resulting spacecraft demonstrates the possibility to meet the NEAR mission requirements using existing technology, 'off-the-shelf' components, and a relatively low-cost launch vehicle.

  8. History of Space Shuttle Rendezvous

    NASA Technical Reports Server (NTRS)

    Goodman, John L.

    2011-01-01

    This technical history is intended to provide a technical audience with an introduction to the rendezvous and proximity operations history of the Space Shuttle Program. It details the programmatic constraints and technical challenges encountered during shuttle development in the 1970s and over thirty years of shuttle missions. An overview of rendezvous and proximity operations on many shuttle missions is provided, as well as how some shuttle rendezvous and proximity operations systems and flight techniques evolved to meet new programmatic objectives. This revised edition provides additional information on Mercury, Gemini, Apollo, Skylab, and Apollo/Soyuz. Some chapters on the Space Shuttle have been updated and expanded. Four special focus chapters have been added to provide more detailed information on shuttle rendezvous. A chapter on the STS-39 mission of April/May 1991 describes the most complex deploy/retrieve mission flown by the shuttle. Another chapter focuses on the Hubble Space Telescope servicing missions. A third chapter gives the reader a detailed look at the February 2010 STS-130 mission to the International Space Station. The fourth chapter answers the question why rendezvous was not completely automated on the Gemini, Apollo, and Space Shuttle vehicles.

  9. Space Shuttle Orbiter onboard rendezvous navigation

    Microsoft Academic Search

    M. J. Little

    1982-01-01

    Much of the work that the Space Shuttle will perform requires a capability to rendezvous with other orbiting objects. The formulation and design philosophy behind the Space Shuttle Orbiter rendezvous navigation system are the subjects of this paper. The current rendezvous navigation design incorporates a Kalman filter to estimate the relative position and velocity. The filter is augmented with state

  10. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Olds, Keith A.; Ohe, Thomas D.

    The rendezvous radar set (RRS) under development will be a key subsystem aboard NASA's new orbital maneuvering vehicle (OMV). The RRS is an X-band all solid-state, monopulse tracking, frequency-hopping, pulse-Doppler radar system. Targets of 1m2 are detected at ranges greater than 4.5 nautical miles, and larger targets are detected at up to 10 nautical miles. The target is then tracked in angle, range, and range rate to a distance of 35 feet from the OMV. In addition to performance and cost, the design drivers for the RRS development have included the minimization of power consumption, size, and weight.

  11. Optical Measurements of Tumbling Rocket Bodies

    NASA Technical Reports Server (NTRS)

    Read, J.; Cowardin, H.; Liou, J.-C.

    2012-01-01

    A component of interest in the active debris removal (ADR) effort in low Earth orbit is spent rocket upper stages. Proximity operations for such missions require an understanding of the tumbling characteristics of these targets. This research was conducted to assist in laying the ground work for realistic ADR mission planning. To better understand the tumbling characteristics of these spent upper stages, the NASA Orbital Debris Program Office has acquired over 400 recorded lightcurves using telescopes located in Colorado and New Mexico. This effort focuses on a population of over 250 Russian SL-8 and SL-16 spent upper stages. The oldest of these have been in orbit for 45 years, and some have exhibited unplanned orbit changes up to 22 years after launch. This paper describes the techniques of how this optical data was acquired and summarizes the optical signatures for this population of targets, including categorization, tumbling period, and investigations into specific targets in which the optical signature changed dramatically over different time periods. Results from period analysis performed on these lightcurves are summarized.

  12. Automated rendezvous and docking with video imagery

    NASA Technical Reports Server (NTRS)

    Rodgers, Mike; Kennedy, Larry Z.

    1991-01-01

    For rendezvous and docking, assessing and tracking relative orientation is necessary within a minimum approach distance. Special target light patterns have previously been considered for use with video sensors for ease of determining relative orientation. A generalization of those approaches is addressed. At certain ranges, the entire structure of the target vehicle constitutes an acceptable target; at closer ranges, substructures will suffice. Acting on the same principle as the human intelligence, these structures can be compared with a memory model to assess the relative orientation and range. Models for comparison are constructed from a CAD facet model and current imagery. This approach requires fast image handling, projection, and comparison techniques which rely on rapidly developing parallel processing technology. Relative orientation and range assessment consists of successful comparison of the perceived target aspect with a known aspect. Generating a known projection from a model within required times, say subsecond times, is only now approaching feasibility. With this capability, rates of comparison used by the human brain can be approached and arbitrary known structures can be compared in reasonable times. Future space programs will have access to powerful computation devices which far exceed even this capability. For example, the possibility will exist to assess unknown structures and then control rendezvous and docking, all at very fast rates. The first step which has the current utility, namely applying this to known structures, is taken.

  13. Hydra Rendezvous and Docking Sensor

    NASA Technical Reports Server (NTRS)

    Roe, Fred; Carrington, Connie

    2007-01-01

    The U.S. technology to support a CEV AR&D activity is mature and was developed by NASA and supporting industry during an extensive research and development program conducted during the 1990's and early 2000 time frame at the Marshall Space Flight Center. Development and demonstration of a rendezvous/docking sensor was identified early in the AR&D Program as the critical enabling technology that allows automated proxinity operations and docking. A first generation rendezvous/docking sensor, the Video Guidance Sensor (VGS) was developed and successfully flown on STS 87 and again on STS 95, proving the concept of a video-based sensor. Advances in both video and signal processing technologies and the lessons learned from the two successful flight experiments provided a baseline for the development of a new generation of video based rendezvous/docking sensor. The Advanced Video Guidance Sensor (AVGS) has greatly increased performance and additional capability for longer-range operation. A Demonstration Automatic Rendezvous Technology (DART) flight experiment was flown in April 2005 using AVGS as the primary proximity operations sensor. Because of the absence of a docking mechanism on the target satellite, this mission did not demonstrate the ability of the sensor to coltrold ocking. Mission results indicate that the rendezvous sensor operated successfully in "spot mode" (2 km acquisition of the target, bearing data only) but was never commanded to "acquire and track" the docking target. Parts obsolescence issues prevent the construction of current design AVGS units to support the NASA Exploration initiative. This flight proven AR&D technology is being modularized and upgraded with additional capabilities through the Hydra project at the Marshall Space Flight Center. Hydra brings a unique engineering approach and sensor architecture to the table, to solve the continuing issues of parts obsolescence and multiple sensor integration. This paper presents an approach to sensor hardware trades, to address the needs of future vehicles that may rendezvous and dock with the International Space Station (ISS). It will also discuss approaches for upgrading AVGS to address parts obsolescence, and concepts for modularizing the sensor to provide configuration flexibility for multiple vehicle applications. Options for complementary sensors to be integrated into the multi-head Hydra system will also be presented. Complementary sensor options include ULTOR, a digital image correlator system that could provide relative six-degree-of-freedom information independently from AVGS, and time-of-flight sensors, which determine the range between vehicles by timing pulses that travel from the sensor to the target and back. Common targets and integrated targets, suitable for use with the multi-sensor options in Hydra, will also be addressed.

  14. The Space Shuttle Ku-band rendezvous radar

    Microsoft Academic Search

    S. C. Iglehart

    1980-01-01

    The Space Shuttle Ku-band integrated radar\\/communications equipment incorporates a pulse-Doppler radar for acquisition and tracking of satellites during rendezvous. The radar can acquire augmented targets at 300 nm and passive targets at 12 nm under computer control. When track is established it provides range, range rate, angle, and angle rate outputs to the orbiter computers and to control panel readouts.

  15. Robot Acting on Moving Bodies (RAMBO): Interaction with Tumbling Objects

    E-print Network

    Ziavras, Sotirios G.

    N90-29022 Robot Acting on Moving Bodies (RAMBO): Interaction with Tumbling Objects Larry S. Davis or control those actions. We are developing a robot system (RAMBO) equipped with a camera, which, given a sequence of simple tasks, can perform these tasks on a tumbling object. RAMBO is given a complete geometric

  16. Robot Acting on Moving Bodies (RAMBO): Interaction with Tumbling Objects

    E-print Network

    DeMenthon, Daniel

    . Robot Acting on Moving Bodies (RAMBO): Interaction with Tumbling Objects Larry S. Davis, Daniel or control those actions. We are developing a robot system (RAMBO) equipped with a camera, which, given a sequence of simple tasks, can perform these tasks on a tumbling object. RAMBO is given a complete geometric

  17. STS-134 Re-Rendezvous Design History

    NASA Technical Reports Server (NTRS)

    Stuit, Timothy D.

    2011-01-01

    In preparation to provide the capability for the Orion spacecraft to rendezvous with the International Space Station (ISS), a new suite of relative navigation sensors are in development and will be tested on one of the final Space Shuttle missions to ISS. The National Aeronautics and Space Administration (NASA) commissioned a flight test of prototypes of the instruments on STS-134, in order to test their performance in the space environment during the nominal rendezvous and docking, as well as a re-rendezvous dedicated to testing the prototype sensors following the undocking of the Space Shuttle Orbiter at the end of the mission. Unlike the initial rendezvous and docking, the re-rendezvous profile would replicate the newly designed Orion coelliptic approach trajectory, something never before attempted with the Shuttle Orbiter. Therefore, there were a number of new parameters that needed to be conceived of, designed, and tested for this re-rendezvous to make the flight test successful. And all of this work had to be integrated with the normal operations of the ISS and Shuttle and had to conform to the constraints of the mission and vehicles. The result of this work is a separation and re-rendezvous trajectory design that will prove not only the design of the relative navigation sensors for the Orion vehicle, but also will serve as a proof of concept for the Orion rendezvous trajectory itself. This document presents the analysis and decision making process involved in attaining the final STS-134 re-rendezvous design.

  18. Tracking laser radar for rendezvous docking - A conceptual design

    NASA Astrophysics Data System (ADS)

    Anegawa, H.; Wakabayashi, Y.; Shimizu, M.; Nagai, M.; Yasugi, T.

    A conceptual design study of an optical rendezvous docking sensor using a semiconductor laser radar was carried out as part of research aimed at the development of the rendezvous and docking technology. The tone ranging method with four different frequencies was used to obtain a maximum range of several tens of kilometers and a ranging accuracy of 5 cm in the 1-km range. A range rate accuracy of 4 cm/s (1-20 km) using the subcarrier Doppler method, and of 1 cm/s (1km - 2 m) using the differential method was shown to be possible. A tracker laser radar was designed which is capable of measuring the LOS angle from the tracking angle with an accuracy of 0.1 deg. The relative attitude can be measured with a CCD image sensor with an accuracy of 0.6 to 0.2 deg; the maximum tracking rate is estimated at 1.8 deg/s.

  19. Rendezvous radar for Space Shuttle Orbiter vehicle

    Microsoft Academic Search

    W. F. McQuillan; A. W. Bologna; D. M. Calabrese

    1974-01-01

    To successfully complete many of the Space Shuttle Program proposed missions involving Orbiter rendezvous with orbiting satellites, some method of detecting and tracking remote targets is desirable. Several studies to establish the requirements for a rendezvous radar system indicated the feasibility of the concept. Extensive application of state of the art components is possible, and system parameters can be determined

  20. Shuttle rendezvous radar performance: evaluation and simulation

    Microsoft Academic Search

    J. W. Griffin; A. C. Lindberg; T. B. Ahn; P. L. Harton

    1989-01-01

    The authors describe the performance evaluation and simulation of the Ku-band shuttle rendezvous radar. Computer simulation, using the radar cross section for specific spacecraft, provided an estimate of rendezvous radar range performance for that spacecraft. The radar cross section model included smooth metallic surfaces, rough surfaces, and shadowing effects, as well as phase differences due to different path lengths to

  1. Automatic procedures generator for orbital rendezvous maneuver

    NASA Technical Reports Server (NTRS)

    Kohn, W.; Van Valkenburg, J. A.; Dunn, C. K.

    1985-01-01

    This paper describes the development of an expert system for defining and dynamically updating procedures for an orbital rendezvous maneuver. The product of the expert system is a procedure represented by a Moore automaton. The construction is recursive and driven by a simulation of the rendezvousing bodies.

  2. Tumbling, an Interactive Way to Move Forward

    NSDL National Science Digital Library

    Hiroko Sano (New York University School of Medicine; Howard Hughes Medical Institute and the Kimmel Center for Biology and Medicine of the Skirball Institute REV)

    2007-11-13

    The migration of Drosophila border cells has become a powerful model with which to genetically identify guidance cues that control the directed migration of a group of interconnected cells. During oogenesis, border cells delaminate from an epithelial layer and move collectively toward the oocyte. In vivo observation has been added to the impressive experimental toolkit available to study border cell migration. These studies reveal two previously unknown migratory behaviors: one in which cells within the border cell cluster constantly change their position, and another called "tumbling," by which the entire border cell cluster rotates forward. Unexpectedly, the same receptor tyrosine kinases control these different modes of migration through separate downstream pathways. An early mode is mediated by the actin regulatory proteins ELMO and Mbc and resembles cellular polarization during individual cell migration; whereas during a later phase, communication between cells, facilitated by mitogen-activated protein kinase and phospholipase C–?, organizes the polarity of the entire cluster.

  3. Shuttle rendezvous and proximity operations

    NASA Technical Reports Server (NTRS)

    Pearson, Don J.

    1990-01-01

    Shuttle rendezvous and proximity operations trajectory control techniques are reviewed and it is noted that they have been affected by many factors including Shuttle system design constraints such as limited forward RCS and single point radar failures. Crew training requirements and mission operations constraints such as large launch windows, flexibility, and contingency profile interrupts are also integral factors. The resulting trajectory control design primarily uses ground support for the launch and orbit adjust phases, standardized crew techniques utilizing onboard software for the relative navigation flight phase, and mission unique manual control for a flexible proximity operations phase.

  4. Tumbling in Turbulence: How much does particle shape effect particle motion?

    NASA Astrophysics Data System (ADS)

    Variano, E. A.; Andersson, H. I.; Zhao, L.; Byron, M.

    2014-12-01

    Natural particles suspended in surface water are often non-spherical. We explore the ways in which particle shape effects particle motion, focusing specifically on how particle rotation is divided into spinning and tumbling components. This, in turn, will effect particle collision, clustering, and settling rates. We focus on idealized axisymmetric particles shaped as rods, discs, and spheroids. They are chosen so as to explain the physics of aspherical-particle motion that will be relevant for natural particles such as plankton, sediment, or aggregates (e.g. oil-mineral aggregates, clay flocs, or bio-sediment aggregates held together by TEP). Our work begins with laboratory measurements of particle motion in a turbulence tank built to mimic the flow found in rivers, estuaries, and the ocean surface mixed layer. We then proceed to direct numerical simulation of particle-flow interactions in sheared turbulence similar to that which is found in the surface water of creeks and rivers. We find that shape has only a very weak effect on particle angular velocity, which is a quantity calculated with respect the global reference frame (i.e. east/north/up). If we analyze rotation in a particle's local frame (i.e. the particle's principle axes of rotation), then particle shape has a strong effect on rotation. In the local frame, rotation is described by two components: tumbling and spinning. We find that rod-shaped particles spin more than they tumble, and we find that disc-shaped particles tumble more than they spin. Such behavior is indicative of how particles respond the the directional influence of vortex tubes in turbulence, and such response has implications for particle motion other than rotation. Understanding particle alignment is relevant for predicting particle-particle collision rates, particle-wall collision rates, and the shear-driven breakup of aggregates. We discuss these briefly in the context of what can be concluded from the rotation data discussed above.

  5. A bead-spring model for running and tumbling of flagellated swimmers: detailed predictions compared to experimental data for E. coli.

    PubMed

    Kong, Miqiu; Wu, Yan; Li, Guangxian; Larson, Ronald G

    2015-02-28

    To study the swimming of the multi-flagellated bacterium Escherichia coli, we deploy a bead-spring hydrodynamic model (Watari and Larson 2010), whose body and flagellar geometry, motor torques, and motor reversals are adjusted to match the experimental observations of the Berg group (Turner et al. 2000; Darnton et al. 2007) during both running and tumbling of the bacterium. In this model, hydrodynamic interactions, which drive swimming, flagellar bundling, and unbundling during swimming and tumbling, are imposed by treating the beads as Stokeslets, imposing torques and counter-torques on the body and flagellum at the flexible joint connecting them to represent the action of motor, and using the Rotne-Prager tensor to model their hydrodynamic interactions with other beads. We explore the behavior of coarse-grained (60-bead) and refined (120-bead) versions of the model, and show that predictions of running speed, helical and body rotation rates, body wobble rates and angles, average tumbling angles, range of tumbling angles, and flagellar re-bundling times are in good agreement with experimental observations by Berg and coworkers. We find that variation in tumbling angle arises from variation in flagellar number and location on the bacterial body, variations in polymorphic transitions of the filaments, and especially from variations in the duration of the tumbling time, which is roughly linearly correlated with tumbling time up to tumbling angles of around 40-50° and more weakly thereafter. The accuracy of the model suggests its usefulness for future studies of swimming of other flagellated swimmers, for predictions of collective phenomena, and for tuning parameters of coarser-grained swimmer models to achieve greater realism. PMID:25591165

  6. Onboard navigation rendezvous expert system

    NASA Technical Reports Server (NTRS)

    Kocen, Michelle

    1991-01-01

    The Onboard Navigation rendezvous expert system is designed to aid the ground flight controller in monitoring the shuttle onboard navigation system. The system is designed to keep track of the navigation sensors and relative state vectors. In addition, the system also keeps an event log and fills out forms usually handled by the flight controller. This expert system is one of the few rendezvous specific systems being developed for the Mission Control Center. The expert system has been in development for six years. Through these years the system has seen hardware, software, and personnel changes. Initial development was done by the Information Systems Directorate (ISD) and Mission Operations Directorate (MOD) at Johnson Space Center. As of October 1, 1991 the system has been turned over to MOD. The system is completely developed except for some minor adjustments to the user interface. The rule base is in the verification stage with total certification of the system due to be completed by May 1992. Test cases for verification are obtained by saving data used for flight controller integrated simulations. The actual data comes from both the shuttle mission simulator and the Mission Control Center Computer. So far no actual flight data has been available. This paper covers all aspects of the system from the development history to the current hardware, software, and use of the system.

  7. Onboard navigation rendezvous expert system

    NASA Astrophysics Data System (ADS)

    Kocen, Michelle

    The Onboard Navigation rendezvous expert system is designed to aid the ground flight controller in monitoring the shuttle onboard navigation system. The system is designed to keep track of the navigation sensors and relative state vectors. In addition, the system also keeps an event log and fills out forms usually handled by the flight controller. This expert system is one of the few rendezvous specific systems being developed for the Mission Control Center. The expert system has been in development for six years. Through these years the system has seen hardware, software, and personnel changes. Initial development was done by the Information Systems Directorate (ISD) and Mission Operations Directorate (MOD) at Johnson Space Center. As of October 1, 1991 the system has been turned over to MOD. The system is completely developed except for some minor adjustments to the user interface. The rule base is in the verification stage with total certification of the system due to be completed by May 1992. Test cases for verification are obtained by saving data used for flight controller integrated simulations. The actual data comes from both the shuttle mission simulator and the Mission Control Center Computer. So far no actual flight data has been available. This paper covers all aspects of the system from the development history to the current hardware, software, and use of the system.

  8. Optical Signature Analysis of Tumbling Rocket Bodies via Laboratory Measurements

    NASA Astrophysics Data System (ADS)

    Cowardin, H.; Lederer, S.; Liou, J.-C.; Ojakangas, G.; Mulrooney, M.

    2012-09-01

    The NASA Orbital Debris Program Office has acquired telescopic lightcurve data on massive intact objects, specifically spent rocket bodies (R/Bs), to ascertain tumble rates in support of the Active Debris Removal (ADR) studies to help remediate the LEO environment. Tumble rates are needed to plan and develop proximity and docking operations for potential future ADR operations. To better characterize and model optical data acquired from ground-based telescopes, the Optical Measurements Center (OMC) at NASA/JSC emulates illumination conditions in space using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. The OMC employs a 75-W Xenon arc lamp as a solar simulator, an SBIG CCD camera with standard Johnson/Bessel filters, and a robotic arm to simulate an object's position and rotation. The OMC does not attempt to replicate the rotation rates, but focuses on ascertaining how an object is rotating as seen from multiple phase angles. The two targets studied are scaled (1:48) SL-8 Cosmos 3M second stages. The first target is painted in the standard Russian government "gray" scheme and the second target is white/orange as used for commercial missions. This paper summarizes results of the two scaled rocket bodies, each observed in three independent rotation states: (a) spin-stabilized rotation (about the long axis), (b) end-over-end rotation, and (c) a 10 degree wobble about the center of mass. The first two cases represent simple spin about either primary axis. The third - what we call "wobble" - represents maximum principal axis rotation, with an inertia tensor that is offset from the symmetry axes. By comparing the resultant phase and orientation-dependent laboratory signatures with actual lightcurves derived from telescopic observations of orbiting R/Bs, we intend to assess the intrinsic R/B rotation states. In the simplest case, simulated R/B behavior coincides with principal axis spin states, while more complex R/B motions can be constructed by combinations of OMC-derived optical signature that together form a rudimentary basis set. The signatures will be presented for specific phase angles for each rocket body and shown in conjunction with acquired optical data from multiple telescope sources. The results of the data show possible correlations between the laboratory data and telescopic data for the rotations states mentioned above (b) and (c), but with limited data the results were not definitive to differentiate between color schemes and rotations. The only rotation that did not correlate with the observed telescopic data was the spin-stabilized rotation.

  9. Credit PSR. This interior view shows the vacuum tumble dryer. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit PSR. This interior view shows the vacuum tumble dryer. The tumble dryer is lined with a water jacket to maintain temperature during the drying of ammonium perchlorate ("AP"); water enters and exits the dryer jacket through the pipe fittings along the horizontal center line of the dryer. The wall at the right is constructed to blow out in the event of an explosion - Jet Propulsion Laboratory Edwards Facility, Oxidizer Dryer Building, Edwards Air Force Base, Boron, Kern County, CA

  10. Control of tumbling in bacterial chemotaxis by divalent cation.

    PubMed Central

    Ordal, G W

    1976-01-01

    Chemotaxis is migration of organisms to higher concentrations of attractant or lower concentrations of repellent. Understanding the switch than controls whether the flagella rotate counterclockwise for swimming or clockwise for tumbling (thrashing about without making much forward progress) is central to understanding chemotaxis of peritrichous bacteria, since chemotaxis results from selective suppression of tumbles. Depletion of divalent cation by chelating agents in the presence of A23187, an ionophore that conveys divalent cation across membrane, causes incessant tumbling in Bacillus subtilis. Small additions of MgCl2 prevent this tumbling. In this tumbling condition, the bacteria which normally swim extensively when given attractant, do not respond even to 10 mM alanine, a strong attractant. MnCl2, by contrast to others potentiated by the ionophore. Permanent cations, including tetraphenylarsonium ion and triphenylmethylphosphonium ion, cause permanent swimming, even in the presence of A23187 and chelating agents. We propose that divalent cation, probably Mg2+ ion, binds to the switch to cause swimming and that, in the absence of divalent cation at the switch, the bacterium tumbles. PMID:816789

  11. Development of an autonomous video rendezvous and docking system, phase 3

    NASA Technical Reports Server (NTRS)

    Tietz, J. C.

    1984-01-01

    Field-of-view limitations proved troublesome. Higher resolution was required. Side thrusters were too weak. The strategy logic was improved and the Kalman filter was augmented to estimate target attitude and tumble rate. Two separate filters were used. The new filter estimates target attitude and angular momentum. The Newton-Raphson iteration improves image interpretation.

  12. In-orbit demonstration of rendezvous laser radar for unmanned autonomous rendezvous docking

    Microsoft Academic Search

    MASAAKI MOKUNO; ISAO KAWANO; TAKASHI SUZUKI

    2004-01-01

    The National Space Development Agency of Japan (NASDA) performed unmanned autonomous rendezvous docking (RVD) experiments using the Engineering Test Satellite VII (ETS-VII) in 1998 and 1999. In these experiments, a rendezvous laser radar (RVR) was used as the primary navigation sensor during the final approach phase (relative distances from 500 m to 2 m). The RVR functioned properly, and its

  13. Modeling E. coli Tumbles by Rotational Diffusion. Implications for Chemotaxis

    PubMed Central

    Saragosti, Jonathan; Silberzan, Pascal; Buguin, Axel

    2012-01-01

    The bacterium Escherichia coli in suspension in a liquid medium swims by a succession of runs and tumbles, effectively describing a random walk. The tumbles randomize incompletely, i.e. with a directional persistence, the orientation taken by the bacterium. Here, we model these tumbles by an active rotational diffusion process characterized by a diffusion coefficient and a diffusion time. In homogeneous media, this description accounts well for the experimental reorientations. In shallow gradients of nutrients, tumbles are still described by a unique rotational diffusion coefficient. Together with an increase in the run length, these tumbles significantly contribute to the net chemotactic drift via a modulation of their duration as a function of the direction of the preceding run. Finally, we discuss the limits of this model in propagating concentration waves characterized by steep gradients. In that case, the effective rotational diffusion coefficient itself varies with the direction of the preceding run. We propose that this effect is related to the number of flagella involved in the reorientation process. PMID:22530021

  14. Automated rendezvous and capture system development and simulation for NASA

    Microsoft Academic Search

    Fred D. Roe; Richard T. Howard; Leslie Murphy

    2004-01-01

    The United States does not have an Automated Rendezvous and Capture\\/Docking (AR&C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. This reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the

  15. Rendezvous radar requirements analysis for mission 3B

    Microsoft Academic Search

    W. L. Hutchison; A. K. Jones

    1975-01-01

    Data are presented verifying the compatibility of currently proposed rendezvous radar measurement accuracies with Mission 3B rendezvous requirements. In addition, data presented indicate a potential for increasing the acceptable time lag between termination of thrusting and availability of accurate measurement data. Additional investigation is recommended to define any acceptable time lag above the current proposed value. Finally, Mission 3B rendezvous

  16. Multiple Radios for Fast Rendezvous in Cognitive Radio Networks

    E-print Network

    Chu, Xiaowen

    , Xiaowen Chu, and Zhiyong Lin Abstract--Rendezvous is a fundamental operation in cognitive radio networks1 Multiple Radios for Fast Rendezvous in Cognitive Radio Networks Lu Yu, Hai Liu, Yiu-Wing Leung. The existing work on rendezvous implicitly assumes that each cognitive user is equipped with one radio (i

  17. Red blood cells and other non-spherical capsules in shear flow: oscillatory dynamics and the tank-treading-to-tumbling transition

    E-print Network

    J. M. Skotheim; T. W. Secomb

    2006-05-26

    We consider the motion of red blood cells and other non-spherical microcapsules dilutely suspended in a simple shear flow. Our analysis indicates that depending on the viscosity, membrane elasticity, geometry and shear rate, the particle exhibits either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behavior in which the two modes occur alternately. For red blood cells, we compute the complete phase diagram and identify a novel tank-treading-to-tumbling transition at low shear rates. Observations of such motions coupled with our theoretical framework may provide a sensitive means of assessing capsule properties.

  18. Rendezvous radar for the orbital maneuvering vehicle

    NASA Technical Reports Server (NTRS)

    Locke, John W.; Olds, Keith A.; Quaid, Thomas

    1991-01-01

    The Rendezvous Radar Set (RRS) was designed at Motorola's Strategic Electronics Division in Chandler, Arizona, to be a key subsystem aboard NASA's Orbital Maneuvering Vehicle (OMV). The unmanned OMV, which was under development at TRW's Federal Systems Division in Redondo Beach, California, was designed to supplement the Shuttle's satellite delivery, retrieval, and maneuvering activities. The RRS was to be used to locate and then provide the OMV with vectoring information to the target satellite (or Shuttle or Space Station) to aid the OMV in making a minimum fuel consumption approach and rendezvous. The OMV development program was halted by NASA in 1990 just as parts were being ordered for the RRS engineering model. The paper presented describes the RRS design and then discusses new technologies, either under development or planned for development at Motorola, that can be applied to radar or alternative sensor solutions for the Automated Rendezvous and Capture problem.

  19. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Olds, Keith A.; Quaid, Thomas

    The Rendezvous Radar Set (RRS) was designed at Motorola's Strategic Electronics Division in Chandler, Arizona, to be a key subsystem aboard NASA's Orbital Maneuvering Vehicle (OMV). The unmanned OMV, which was under development at TRW's Federal Systems Division in Redondo Beach, California, was designed to supplement the Shuttle's satellite delivery, retrieval, and maneuvering activities. The RRS was to be used to locate and then provide the OMV with vectoring information to the target satellite (or Shuttle or Space Station) to aid the OMV in making a minimum fuel consumption approach and rendezvous. The OMV development program was halted by NASA in 1990 just as parts were being ordered for the RRS engineering model. The paper presented describes the RRS design and then discusses new technologies, either under development or planned for development at Motorola, that can be applied to radar or alternative sensor solutions for the Automated Rendezvous and Capture problem.

  20. Electro-optical rendezvous and docking sensors

    NASA Technical Reports Server (NTRS)

    Tubbs, David J.; Kesler, Lynn O.; Sirko, Robert J.

    1991-01-01

    Electro-optical sensors provide unique and critical functionality for space missions requiring rendezvous, docking, and berthing. McDonnell Douglas is developing a complete rendezvous and docking system for both manned and unmanned missions. This paper examines our sensor development and the systems and missions which benefit from rendezvous and docking sensors. Simulation results quantifying system performance improvements in key areas are given, with associated sensor performance requirements. A brief review of NASA-funded development activities and the current performance of electro-optical sensors for space applications is given. We will also describe current activities at McDonnell Douglas for a fully functional demonstration to address specific NASA mission needs.

  1. Concept definition study for recovery of tumbling satellites. Volume 2: Supporting research and technology report

    NASA Technical Reports Server (NTRS)

    Cable, D. A.; Derocher, W. L., Jr.; Cathcart, J. A.; Keeley, M. G.; Madayev, L.; Nguyen, T. K.; Preese, J. R.

    1986-01-01

    A number of areas of research and laboratory experiments were identified which could lead to development of a cost efficient remote, disable satellite recovery system. Estimates were planned of disabled satellite motion. A concept is defined as a Tumbling Satellite Recovery kit which includes a modular system, composed of a number of subsystem mechanisms that can be readily integrated into varying combinations. This would enable the user to quickly configure a tailored remote, disabled satellite recovery kit to meet a broad spectrum of potential scenarios. The capability was determined of U.S. Earth based satellite tracking facilities to adequately determine the orientation and motion rates of disabled satellites.

  2. The real-time operations of the Space Shuttle Orbiter during rendezvous and proximity operations

    NASA Astrophysics Data System (ADS)

    Dougherty, Andrew; Meyer, Chris

    The Space Shuttle Orbiter is the only U.S. spacecraft in operation today that routinely performs an orbital rendezvous with another spacecraft. The trajectory planning and training of both flight crews and ground operations personnel required to achieve a 100 percent success rate is considerable. The preflight planning and training can be reduced through very simple design considerations of a new space vehicle.

  3. UNDER-ACTUATED CONTROLLABILITY FOR SPACECRAFT RENDEZVOUS

    E-print Network

    Virginia Tech

    UNDER-ACTUATED CONTROLLABILITY FOR SPACECRAFT RENDEZVOUS Andrew Rogers, Craig Woolsey, Robert Mc parameterizations of equations of motion . . . . . 5 iv #12;Andrew Rogers, Craig Woolsey, Robert McGwier 1 #12;The authors would like to thank Dr. Andrew Sinclair of Auburn Univer- sity for the helpful

  4. Laser space rendezvous and docking tradeoff

    Microsoft Academic Search

    S. Adelman; S. Levinson; P. Raber; F. Weindling

    1974-01-01

    A spaceborne laser radar (LADAR) was configured to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. The LADAR, configurated using existing pulsed CO2 laser technology and a 1980 system technology baseline, is well suited for the envisioned space tug missions. The performance of a family of candidate LADARS was analyzed. Tradeoff studies as a

  5. Rendezvous radar for the orbital maneuvering vehicle

    Microsoft Academic Search

    John W. Locke; Keith A. Olds; Thomas Quaid

    1991-01-01

    The Rendezvous Radar Set (RRS) was designed at Motorola's Strategic Electronics Division in Chandler, Arizona, to be a key subsystem aboard NASA's Orbital Maneuvering Vehicle (OMV). The unmanned OMV, which was under development at TRW's Federal Systems Division in Redondo Beach, California, was designed to supplement the Shuttle's satellite delivery, retrieval, and maneuvering activities. The RRS was to be used

  6. Soviet automated rendezvous and docking system overview

    Microsoft Academic Search

    Elaine M. Hinman; David M. Bushman

    1991-01-01

    The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing

  7. Link Rendezvous Protocol for Cognitive Radio Networks

    E-print Network

    Turgut, Damla

    architectures, individual radio nodes sense the local spectrum and choose operating frequencies and bandwidthsLink Rendezvous Protocol for Cognitive Radio Networks Brent Horine and Damla Turgut School and evolution I. INTRODUCTION Some cognitive radio (CR) applications require the ability to form networks

  8. Multiple NEO Rendezvous Using Solar Sail Propulsion

    NASA Technical Reports Server (NTRS)

    Johnson, Les; Alexander, Leslie; Fabisinski, Leo; Heaton, Andy; Miernik, Janie; Stough, Rob; Wright, Roosevelt; Young, Roy

    2012-01-01

    The NASA Marshall Space Flight Center (MSFC) Advanced Concepts Office performed an assessment of the feasibility of using a near-term solar sail propulsion system to enable a single spacecraft to perform serial rendezvous operations at multiple Near Earth Objects (NEOs) within six years of launch on a small-to-moderate launch vehicle. The study baselined the use of the sail technology demonstrated in the mid-2000 s by the NASA In-Space Propulsion Technology Project and is scheduled to be demonstrated in space by 2014 as part of the NASA Technology Demonstration Mission Program. The study ground rules required that the solar sail be the only new technology on the flight; all other spacecraft systems and instruments must have had previous space test and qualification. The resulting mission concept uses an 80-m X 80-m 3-axis stabilized solar sail launched by an Athena-II rocket in 2017 to rendezvous with 1999 AO10, Apophis and 2001 QJ142. In each rendezvous, the spacecraft will perform proximity operations for approximately 30 days. The spacecraft science payload is simple and lightweight; it will consist of only the multispectral imager flown on the Near Earth Asteroid Rendezvous (NEAR) mission to 433 Eros and 253 Mathilde. Most non-sail spacecraft systems are based on the Messenger mission spacecraft. This paper will describe the objectives of the proposed mission, the solar sail technology to be employed, the spacecraft system and subsystems, as well as the overall mission profile.

  9. Multiple NEO Rendezvous Using Solar Sails

    NASA Technical Reports Server (NTRS)

    Johnson, Les; Alexander, Leslie; Fabisinski, Leo; Heaton, Andy; Miernik, Janie; Stough, Rob; Wright, Roosevelt; Young, Roy

    2012-01-01

    Mission concept is to assess the feasibility of using solar sail propulsion to enable a robotic precursor that would survey multiple Near Earth Objects (NEOs) for potential future human visits. Single spacecraft will rendezvous with and image 3 NEOs within 6 years of launch

  10. Interstellar rendezvous missions employing fission propulsion systems

    Microsoft Academic Search

    Roger X. Lenard; Ronald J. Lipinski

    2000-01-01

    There has been a conventionally held nostrum that fission system specific power and energy content is insufficient to provide the requisite high accelerations and velocities to enable interstellar rendezvous missions within a reasonable fraction of a human lifetime. As a consequence, all forms of alternative mechanisms that are not yet, and may never be technologically feasible, have been proposed, including

  11. Designing the STS-134 Re-Rendezvous: A Preparation for Future Crewed Rendezvous Missions

    NASA Technical Reports Server (NTRS)

    Stuit, Timothy D.

    2011-01-01

    In preparation to provide the capability for the Orion spacecraft, also known as the Multi-Purpose Crew Vehicle (MPCV), to rendezvous with the International Space Station (ISS) and future spacecraft, a new suite of relative navigation sensors are in development and were tested on one of the final Space Shuttle missions to ISS. The National Aeronautics and Space Administration (NASA) commissioned a flight test of prototypes of the Orion relative navigation sensors on STS-134, in order to test their performance in the space environment during the nominal rendezvous and docking, as well as a re-rendezvous dedicated to testing the prototype sensors following the undocking of the Space Shuttle orbiter at the end of the mission. Unlike the rendezvous and docking at the beginning of the mission, the re-rendezvous profile replicates the newly designed Orion coelliptic approach trajectory, something never before attempted with the shuttle orbiter. Therefore, there were a number of new parameters that needed to be conceived of, designed, and tested for this rerendezvous to make the flight test successful. Additionally, all of this work had to be integrated with the normal operations of the ISS and shuttle and had to conform to the constraints of the mission and vehicles. The result of this work is a separation and rerendezvous trajectory design that would not only prove the design of the relative navigation sensors for the Orion vehicle, but also would serve as a proof of concept for the Orion rendezvous trajectory itself. This document presents the analysis and decision making process involved in attaining the final STS-134 re-rendezvous design.

  12. Laser space rendezvous and docking tradeoff

    NASA Technical Reports Server (NTRS)

    Adelman, S.; Levinson, S.; Raber, P.; Weindling, F.

    1974-01-01

    A spaceborne laser radar (LADAR) was configured to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. The LADAR, configurated using existing pulsed CO2 laser technology and a 1980 system technology baseline, is well suited for the envisioned space tug missions. The performance of a family of candidate LADARS was analyzed. Tradeoff studies as a function of size, weight, and power consumption were carried out for maximum ranges of 50, 100, 200, and 300 nautical miles. The investigation supports the original contention that a rendezvous and docking LADAR can be constructed to offer a cost effective and reliable solution to the envisioned space missions. In fact, the CO2 ladar system offers distinct advantages over other candidate systems.

  13. Tracking techniques for space shuttle rendezvous

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The space shuttle rendezvous radar has a requirement to track cooperative and non-cooperative targets. For this reason the Lunar Module (LM) Rendezvous Radar was modified to incorporate the capability of tracking a non-cooperative target. The modifications are discussed. All modifications except those relating to frequency diversity were completed, and system tests were performed to confirm proper performance in the non-cooperative mode. Frequency diversity was added to the radar and to the special test equipment, and then system tests were performed. This last set of tests included re-running the tests of the non-cooperative mode without frequency diversity, followed by tests with frequency diversity and tests of operation in the original cooperative mode.

  14. Radar Performance Improvement. Angle Tracking Modification to Fire Control Radar System for Space Shuttle Rendezvous

    NASA Technical Reports Server (NTRS)

    Little, G. R.

    1976-01-01

    The AN/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made by a Ku-Band noncoherent pulse radar.

  15. Rendezvous radar requirements analysis for mission 3B

    NASA Technical Reports Server (NTRS)

    Hutchison, W. L.; Jones, A. K.

    1975-01-01

    Data are presented verifying the compatibility of currently proposed rendezvous radar measurement accuracies with Mission 3B rendezvous requirements. In addition, data presented indicate a potential for increasing the acceptable time lag between termination of thrusting and availability of accurate measurement data. Additional investigation is recommended to define any acceptable time lag above the current proposed value. Finally, Mission 3B rendezvous performance is shown to be sensitive to variations in the relative downrange position dispersions at insertion. It is therefore recommended that insertion relative state dispersions used in studies of 3B rendezvous be reviewed when results of 3B ascent dispersion studies are available.

  16. Autonomous Rendezvous and Docking Conference, volume 1

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This document consists of the presentation submitted at the Autonomous Rendezvous and Docking (ARD) Conference. It contains three volumes: ARD hardware technology; ARD software technology; and ARD operations. The purpose of this conference is to identify the technologies required for an on orbit demonstration of the ARD, assess the maturity of these technologies, and provide the necessary insight for a quality assessment of the programmatic management, technical, schedule, and cost risks.

  17. Autonomous Rendezvous and Docking Conference, volume 3

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This document consists of the presentation submitted at the Autonomous Rendezvous and Docking (ARD) Conference. The document contains three volumes: ARD hardware technology; ARD software technology; and ARD operations. The purpose of this conference is to identify the technologies required for an on orbit demonstration of ARD, assess the maturity of these technologies, and provide the necessary insight for a quality assessment of programmatic management, technical, schedule, and cost risks.

  18. Rendezvous radar for the orbital maneuvering vehicle

    Microsoft Academic Search

    J. W. Locke; K. A. Olds; T. D. Ohe

    1990-01-01

    The rendezvous radar set (RRS) under development will be a key subsystem aboard NASA's new orbital maneuvering vehicle (OMV). The RRS is an X-band all solid-state, monopulse tracking, frequency-hopping, pulse-Doppler radar system. Targets of 1 m2 are detected at ranges greater than 4.5 nautical miles, and larger targets are detected at up to 10 nautical miles. The target is then

  19. Rendezvous radar for the orbital maneuvering vehicle

    Microsoft Academic Search

    John W. Locke; Keith A. Olds; Thomas D. Ohe

    1990-01-01

    The rendezvous radar set (RRS) under development will be a key subsystem aboard NASA's new orbital maneuvering vehicle (OMV). The RRS is an X-band all solid-state, monopulse tracking, frequency-hopping, pulse-Doppler radar system. Targets of 1m2 are detected at ranges greater than 4.5 nautical miles, and larger targets are detected at up to 10 nautical miles. The target is then tracked

  20. Multiple exposure of Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Multiple exposure of Rendezvous Docking Simulator. Francis B. Smith, described the simulator as follows: 'The rendezvous and docking operation of the Gemini spacecraft with the Agena and of the Apollo Command Module with the Lunar Excursion Module have been the subject of simulator studies for several years. [This figure] illustrates the Gemini-Agena rendezvous docking simulator at Langley. The Gemini spacecraft was supported in a gimbal system by an overhead crane and gantry arrangement which provided 6 degrees of freedom - roll, pitch, yaw, and translation in any direction - all controllable by the astronaut in the spacecraft. Here again the controls fed into a computer which in turn provided an input to the servos driving the spacecraft so that it responded to control motions in a manner which accurately simulated the Gemini spacecraft.' Published in Barton C. Hacker and James M. Grimwood, On the Shoulders of Titans: A History of Project Gemini, NASA SP-4203; Francis B. Smith, 'Simulators for Manned Space Research,' Paper presented at the 1966 IEEE International convention, March 21-25, 1966.

  1. Concept definition study for recovery of tumbling satellites. Volume 1: Executive summary, study results

    NASA Technical Reports Server (NTRS)

    Cable, D. A.; Derocher, W. L., Jr.; Cathcart, J. A.; Keeley, M. G.; Madayev, L.; Nguyen, T. K.; Preese, J. R.

    1986-01-01

    The first assessment is made of the design requirements and conceptual definition of a front end kit to be transported on the currently defined Orbital Maneuvering Vehicle (OMV) and the Space Transportation System Shuttle Orbiter, to conduct remote, teleoperated recovery of disabled and noncontrollable, tumbling satellites. Previous studies did not quantify the dynamic characteristics of a tumbling satellite, nor did they appear to address the full spectrum of Tumbling Satellite Recovery systems requirements. Both of these aspects are investigated with useful results.

  2. Deformation, orientation and bursting of microcapsules in simple shear flow: Wrinkling processes, tumbling and swinging motions

    NASA Astrophysics Data System (ADS)

    Unverfehrt, A.; Koleva, I.; Rehage, H.

    2015-04-01

    In a series of experiments we studied the deformation and orientation behaviour of microcapsules in simple shear flow. For a large number of capsules we observed folding processes which were induced by the bending resistance, by membrane pre-stresses or the mechanical asymmetry of the surrounding viscoelastic wall materials. Periodic oscillations of the inclination angle were detected for non-spherical particles. At low shear rates a tumbling motion occurred in which the capsule turned around its axis. A swinging mode at evaluated shear rates was accompanied by tank-treading motions, a rotation of the membrane around the capsule core. Between these two well-known motions we also observed an intermittent regime.

  3. Orbit determination of the Comet Rendezvous/Asteroid Flyby mission - Post-rendezvous phases

    NASA Technical Reports Server (NTRS)

    Miller, James K.; Wood, Lincoln J.; Weeks, Connie J.

    1989-01-01

    Orbit determination during the post-rendezvous phases of the Comet Rendezvous/Asteroid Flyby mission is described. The orbit determination process is discussed, with emphasis placed on optical imaging of landmarks and Doppler tracking. Rotational dynamics are introduced for the cometary nucleus. State estimation errors are given for spacecraft trajectory prediction and cometary nucleus attitude prediction. Estimation errors are also given for parameters that describe the cometary nucleus such as moments of inertia and gravity harmonics. The orbit determination performance in support of science observations while in orbit about the nucleus is described.

  4. Polishing and local planarization of plastic spherical capsules using tumble finishing

    NASA Astrophysics Data System (ADS)

    Suratwala, T. I.; Steele, W. A.; Feit, M. D.; Moreno, K.; Stadermann, M.; Fair, J.; Chen, K.; Nikroo, A.; Youngblood, K.; Wu, K.

    2012-11-01

    A new method (a variant of tumble finishing) for polishing and achieving local planarization on precision spherical, plastic capsules is described. Such capsules have niche applications, such as ablators used in high-peak-power laser targets for fusion energy research. The as-manufactured ablators contain many shallow domes (many 100's of nm high and a few 10's of ?m wide) on the outer surface which are undesirable due to contributions to instabilities during implosion. These capsules were polished (i.e., tumble finished) by rotating a cylindrical vial containing the capsule, many borosilicate glass or zirconia media, and an aqueous-based colloidal silica polishing slurry. During tumble finishing, the relative media/capsule motions cause multiple, random sliding spherical-spherical Hertzian contacts, resulting in material removal, and possibly plastic deformation, on the capsule. As a result, the domes were observed to locally planarize (i.e., converge to lower heights). Utilizing the correct kinematics (i.e., the characteristics of the media/capsule motions), as controlled by the vial rotation rate and the fill fraction of media and slurry, the high velocity downward circumferential media motions were avoided, preventing fracturing of the fragile capsules. Also, the resulting post-polished surface roughness on the capsule was found to scale with the initial media surface roughness. Hence, pre-polishing the media greatly reduced the roughness of the media and thus the roughness of the polished capsule. A material removal model is described based on the Preston model and spherical-spherical Hertzian contacts which shows reasonable agreement with measured average removal rates of 35 ± 15 nm/day and which serves as a valuable tool to scale the polishing behavior with changes in process variables. Narrow domes were observed to planarize more rapidly than wider domes. A local planarization convergence model is also described, based on the concept of workpiece-lap mismatch where the local pressure, and hence removal, varies with the gap at the interface contact. The calculated rate and shape evolution of various size isolated domes compares well with the experimental data.

  5. A modified Rendezvous ERCP technique in duodenal diverticulum

    PubMed Central

    Odabasi, Mehmet; Yildiz, Mehmet Kamil; Abuoglu, Haci Hasan; Eris, Cengiz; Ozkan, Erkan; Gunay, Emre; Aktekin, Ali; Muftuoglu, MA Tolga

    2013-01-01

    AIM: To postoperative endoscopic retrograde cholangiopancreatography (ERCP) failure, we describe a modified Rendezvous technique for an ERCP in patients operated on for common bile duct stone (CBDS) having a T-tube with retained CBDSs. METHODS: Five cases operated on for CBDSs and having retained stones with a T-tube were referred from other hospitals located in or around Istanbul city to the ERCP unit at the Haydarpasa Numune Education and Research Hospital. Under sedation anesthesia, a sterile guide-wire was inserted via the T-tube into the common bile duct (CBD) then to the papilla. A guide-wire was held by a loop snare and removed through the mouth. The guide-wire was inserted into the sphincterotome via the duodenoscope from the tip to the handle. The duodenoscope was inserted down to the duodenum with a sphincterotome and a guide-wire in the working channel. With the guidance of a guide-wire, the ERCP and sphincterotomy were successfully performed, the guide-wire was removed from the T-tube, the stones were removed and the CBD was reexamined for retained stones by contrast. RESULTS: An ERCP can be used either preoperatively or postoperatively. Although the success rate in an isolated ERCP treatment ranges from up to 87%-97%, 5%-10% of the patients require two or more ERCP treatments. If a secondary ERCP fails, the clinicians must be ready for a laparoscopic or open exploration. A duodenal diverticulum is one of the most common failures in an ERCP, especially in patients with an intradiverticular papilla. For this small group of patients, an antegrade cannulation via a T-tube can improve the success rate up to nearly 100%. CONCLUSION: The modified Rendezvous technique is a very easy method and increases the success of postoperative ERCP, especially in patients with large duodenal diverticula and with intradiverticular papilla. PMID:24255749

  6. New millennium ST6 autonomous rendezvous experiment (ARX)

    Microsoft Academic Search

    Richard P. Kornfeld; Robert L. Bunker; Gordy C. Cucullu; John C. Essmiller; Fred Y. Hadaegh; C. Christian Liebe; Curtis W. Padgett; Edward C. Wong

    2003-01-01

    This paper presents an overview of the new millennium Space Technology 6 (ST6) Autonomous Rendezvous Experiment (ARX) mission and system. ARX is to be hosted as a payload on a United States Air Force research spacecraft. Launch is currently planned for the fall of 2004. The objective of the ARX experiment is to demonstrate and characterize an autonomous rendezvous system

  7. GPS aided rendezvous and docking with a commercial space platform

    Microsoft Academic Search

    D. Oberg; C. Cook; P. Gulman; T. Taylor

    1992-01-01

    The OUTPOST platform is a commercial space platform constructed on a salvaged Space Shuttle External Tank which will provide low cost access to Low Earth Orbit operations after its launch in 1996. The platform will rendezvous with several types of vehicles during its operational life. A GPS-based rendezvous and docking system which will support all projected mission operations with established

  8. Multiple Radios for Effective Rendezvous in Cognitive Radio Networks

    E-print Network

    Chu, Xiaowen

    Multiple Radios for Effective Rendezvous in Cognitive Radio Networks Lu Yu1 , Hai Liu1 , Yiu in cognitive radio networks (CRNs) for establishing a communication link on a commonly-available channel, we investigate the rendezvous problem in CRNs where cognitive users are equipped with multiple radios

  9. Supervised autonomous rendezvous and docking system technology evaluation

    Microsoft Academic Search

    Neville I. Marzwell

    1991-01-01

    Technology for manned space flight is mature and has an extensive history of the use of man-in-the-loop rendezvous and docking, but there is no history of automated rendezvous and docking. Sensors exist that can operate in the space environment. The Shuttle radar can be used for ranges down to 30 meters, Japan and France are developing laser rangers, and considerable

  10. Tracking laser radar for rendezvous docking - A conceptual design

    Microsoft Academic Search

    H. Anegawa; Y. Wakabayashi; M. Shimizu; M. Nagai; T. Yasugi

    1989-01-01

    A conceptual design study of an optical rendezvous docking sensor using a semiconductor laser radar was carried out as part of research aimed at the development of the rendezvous and docking technology. The tone ranging method with four different frequencies was used to obtain a maximum range of several tens of kilometers and a ranging accuracy of 5 cm in

  11. Scanning laser radar system for rendezvous and docking in space

    Microsoft Academic Search

    Hirobumi Saito; Ichiro Nakatani; Keiken Ninomiya; Akira Furuya

    1987-01-01

    A scanning laser radar system for rendezvous and docking in space is being developed. This laser radar system will be utilized in an autonomous satellite retrieval experiment which is planned as one of the future missions to be conducted on Japanese Space Flyer Unit (SFU) in 1990s. Rendezvous and retrieval operation will be automatically performed by on-board instruments. The laser

  12. Relative navigation requirements for automatic rendezvous and capture systems

    Microsoft Academic Search

    Peter M. Kachmar; Robert J. Polutchko; William Chu; Moises Montez

    1991-01-01

    This paper will discuss in detail the relative navigation system requirements and sensor trade-offs for Automatic Rendezvous and Capture. Rendezvous navigation filter development will be discussed in the context of navigation performance requirements for a 'Phase One' AR&C system capability. Navigation system architectures and the resulting relative navigation performance for both cooperative and uncooperative target vehicles will be assessed. Relative

  13. Powered Safe Abort for Autonomous Rendezvous of Spacecraft

    E-print Network

    How, Jonathan P.

    Powered Safe Abort for Autonomous Rendezvous of Spacecraft Louis Breger and Jonathan P. How MIT-optimized rendezvous trajectories. These trajectories guarantee the existence of known powered abort trajectories the existence of known active safe abort trajectories for a large class of possible spacecraft anomalies

  14. Fault-Tolerant Rendezvous in Networks Jeremie Chalopin1

    E-print Network

    Boyer, Edmond

    Fault-Tolerant Rendezvous in Networks J´er´emie Chalopin1 , Yoann Dieudonn´e2 , Arnaud Labourel1 network maintenance task. In this paper we study a fault-tolerant version of the rendezvous problem´ebec, Canada Abstract. Two mobile agents, starting from different nodes of an un- known network, have to meet

  15. Tumbling flow in loop-scavenged two-stroke engines

    SciTech Connect

    Tsui, Y.Y.; Cheng, H.P. [National Chiao Tung Univ., Hsinchu (Taiwan, Province of China). Dept. of Mechanical Engineering

    1995-12-01

    A multidimensional calculation procedure is used to investigate the flow in loop-scavenged two-stroke engine with curved cylinder heads. Five different cylinder heads are considered. The curvature of cylinder head increases from case 1 to case 4. In case 5 the head curvature is further increased, but it is shaped in the radially outer region. Calculations reveal that a tumbling vortex forms after the exhaust port is closed and the vortex constantly dominates the flow structure in the cylinder throughout the compression period. With high head curvatures the vortex is well organized and occupies the entire cylinder volume in the late compression stage. Due to compression of the better organized tumbling vortex by the moving piston more energy cascades from mean flow to turbulence in the high curvature cases 3 and 4. As for case 5, the larger clearance in the bowl center region leads to lower shear stresses and, thus, the turbulence augmentation phenomenon is less prominent than that for cases 3 and 4.

  16. SIMONE: Interplanetary microsatellites for NEO rendezvous missions

    NASA Astrophysics Data System (ADS)

    Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

    2006-10-01

    The paper summarises a novel mission concept called SIMONE (smallsat intercept missions to objects near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of near Earth objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120 kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other on-board systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

  17. SIMONE: interplanetary microsatellites for NEO rendezvous missions

    NASA Astrophysics Data System (ADS)

    Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

    2003-11-01

    The paper summarises a novel mission concept called SIMONE (Smallsat Intercept Missions to Objects Near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of Near Earth Objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other onboard systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

  18. Rendezvous radar for the orbital maneuvering vehicle

    NASA Technical Reports Server (NTRS)

    Locke, John W.; Olds, Keith; Parks, Howard

    1991-01-01

    This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

  19. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Olds, Keith; Parks, Howard

    This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

  20. Simulation models for autonomous rendezvous and capture

    NASA Technical Reports Server (NTRS)

    Smith, Nick G.; Mckinnis, Jim A.; Early, Sid M.

    1991-01-01

    Autonomous rendezvous and capture (AR&C) is a critical space technology with significant application to a variety of missions. Martin Marietta Astronautics Group (MMAG) has been developing AR&C technical capability in support of several recent NASA contracts. The use of AR&C for the Mars Rover/Sample Return (MRSR) mission was studied through a contract with JSC. Incorporation of AR&C in the Space Transportation Vehicle (STV) lunar mission was studied through a contract with MSFC. The MMAG has also been developing AR&C simulation capability under independent research and development studies. Simulation development was driven by two goals: comprehensive software simulation of the autonomous rendezvous and capture mission from launch to final capture; and integration of the overall software and hardware simulation to support an AR&C flight demonstration. This presentation will highlight the AR&C software simulation tools and analyze results from their application to the STV lunar mission. Plans for an integrated software and hardware simulation will also be summarized.

  1. The comet rendezvous asteroid flyby mission

    NASA Technical Reports Server (NTRS)

    Morrison, David; Neugebauer, Marcia; Weissman, Paul R.

    1989-01-01

    The Comet Rendezvous Asteroid Flyby (CRAF) mission is designed to answer the many questions raised by the Halley missions by exploring a cometary nucleus in detail, following it around its orbit and studying its changing activity as it moves closer to and then away from the Sun. In addition, on its way to rendezvous with the comet, CRAF will fly by a large, primitive class main belt asteroid and will return valuable data for comparison with the comet results. The selected asteroid is 449 Hamburga with a diameter of 88 km and a surface composition of carbonaceous chondrite meteorites. The expected flyby date is January, 1998. The CRAF spacecraft will continue to make measurements in orbit around the cometary nucleus as they both move closer to the Sun, until the dust and gas hazard becomes unsafe. At that point the spacecraft will move in and out between 50 and 2,500 kilometers to study the inner coma and the cometary ionosphere, and to collect dust and gas samples for onboard analysis. Following perihelion, the spacecraft will make a 50,000 km excursion down the comet's tail, further investigating the solar wind interaction with the cometary atmosphere. The spacecraft will return to the vicinity of the nucleus about four months after perihelion to observe the changes that have taken place. If the spacecraft remains healthy and adequate fuel is still onboard, an extended mission to follow the comet nucleus out to aphelion is anticipated.

  2. Demonstration of Autonomous Rendezvous Technology (DART) Project Summary

    NASA Technical Reports Server (NTRS)

    Rumford, TImothy E.

    2003-01-01

    Since the 1960's, NASA has performed numerous rendezvous and docking missions. The common element of all US rendezvous and docking is that the spacecraft has always been piloted by astronauts. Only the Russian Space Program has developed and demonstrated an autonomous capability. The Demonstration of Autonomous Rendezvous Technology (DART) project currently funded under NASA's Space Launch Initiative (SLI) Cycle I, provides a key step in establishing an autonomous rendezvous capability for the United States. DART's objective is to demonstrate, in space, the hardware and software necessary for autonomous rendezvous. Orbital Sciences Corporation intends to integrate an Advanced Video Guidance Sensor and Autonomous Rendezvous and Proximity Operations algorithms into a Pegasus upper stage in order to demonstrate the capability to autonomously rendezvous with a target currently in orbit. The DART mission will occur in April 2004. The launch site will be Vandenburg AFB and the launch vehicle will be a Pegasus XL equipped with a Hydrazine Auxiliary Propulsion System 4th stage. All mission objectives will be completed within a 24 hour period. The paper provides a summary of mission objectives, mission overview and a discussion on the design features of the chase and target vehicles.

  3. Expert system isssues in automated, autonomous space vehicle rendezvous

    NASA Technical Reports Server (NTRS)

    Goodwin, Mary Ann; Bochsler, Daniel C.

    1987-01-01

    The problems involved in automated autonomous rendezvous are briefly reviewed, and the Rendezvous Expert (RENEX) expert system is discussed with reference to its goals, approach used, and knowledge structure and contents. RENEX has been developed to support streamlining operations for the Space Shuttle and Space Station program and to aid definition of mission requirements for the autonomous portions of rendezvous for the Mars Surface Sample Return and Comet Nucleus Sample return unmanned missions. The experience with REMEX to date and recommendations for further development are presented.

  4. Robot Acting on Moving Bodies (RAMBO): Interaction with tumbling objects

    NASA Technical Reports Server (NTRS)

    Davis, Larry S.; Dementhon, Daniel; Bestul, Thor; Ziavras, Sotirios; Srinivasan, H. V.; Siddalingaiah, Madhu; Harwood, David

    1989-01-01

    Interaction with tumbling objects will become more common as human activities in space expand. Attempting to interact with a large complex object translating and rotating in space, a human operator using only his visual and mental capacities may not be able to estimate the object motion, plan actions or control those actions. A robot system (RAMBO) equipped with a camera, which, given a sequence of simple tasks, can perform these tasks on a tumbling object, is being developed. RAMBO is given a complete geometric model of the object. A low level vision module extracts and groups characteristic features in images of the object. The positions of the object are determined in a sequence of images, and a motion estimate of the object is obtained. This motion estimate is used to plan trajectories of the robot tool to relative locations rearby the object sufficient for achieving the tasks. More specifically, low level vision uses parallel algorithms for image enhancement by symmetric nearest neighbor filtering, edge detection by local gradient operators, and corner extraction by sector filtering. The object pose estimation is a Hough transform method accumulating position hypotheses obtained by matching triples of image features (corners) to triples of model features. To maximize computing speed, the estimate of the position in space of a triple of features is obtained by decomposing its perspective view into a product of rotations and a scaled orthographic projection. This allows use of 2-D lookup tables at each stage of the decomposition. The position hypotheses for each possible match of model feature triples and image feature triples are calculated in parallel. Trajectory planning combines heuristic and dynamic programming techniques. Then trajectories are created using dynamic interpolations between initial and goal trajectories. All the parallel algorithms run on a Connection Machine CM-2 with 16K processors.

  5. Current status of laparoendoscopic rendezvous in the treatment of cholelithiasis with concomitant choledocholithiasis.

    PubMed

    Baloyiannis, Ioannis; Tzovaras, George

    2015-06-25

    The current evidence in favor of the laparoendoscopic rendezvous is promising and demonstrates the main advantages of this technique in regard to shorter hospital stay and selective cannulation of the common bile duct (CBD), avoiding thus the inadvertent cannulation of the pancreatic duct. In addition, in the rendezvous technique the contrast medium is not injected retrogradely as during the traditional endoscopic retrograde cholangiopancreatography (ERCP), when the medium accidentally could be injected under pressure into the pancreatic duct. The RV technique minimizes that risk. Both these main advantages of the RV technique over the classic ERCP, are related with a significant lower incidence of hyperamylasemia and post-ERCP pancreatitis, compared with the traditional two stage procedure. Choledocholithiasis is present in 10% to 15% of patients undergoing cholecystectomy. To date, the ideal management of CBD stones remains controversial. Prospective randomized trials have shown that laparoscopic management of the CBD stones, as a single stage procedure, is the most efficient and cost effective method of treatment. Laparoendoscopic rendezvous has been proposed as an alternative single stage approach. Several studies have shown the effective use of this technique in the treatment of CBD stones by improving patient compliance and clinical results including shorter hospital stay, higher success rate and less cost. The current evidence about the use of this technique presented in this review article is promising and demonstrates the main advantages of the procedure. PMID:26140098

  6. Current status of laparoendoscopic rendezvous in the treatment of cholelithiasis with concomitant choledocholithiasis

    PubMed Central

    Baloyiannis, Ioannis; Tzovaras, George

    2015-01-01

    The current evidence in favor of the laparoendoscopic rendezvous is promising and demonstrates the main advantages of this technique in regard to shorter hospital stay and selective cannulation of the common bile duct (CBD), avoiding thus the inadvertent cannulation of the pancreatic duct. In addition, in the rendezvous technique the contrast medium is not injected retrogradely as during the traditional endoscopic retrograde cholangiopancreatography (ERCP), when the medium accidentally could be injected under pressure into the pancreatic duct. The RV technique minimizes that risk. Both these main advantages of the RV technique over the classic ERCP, are related with a significant lower incidence of hyperamylasemia and post-ERCP pancreatitis, compared with the traditional two stage procedure. Choledocholithiasis is present in 10% to 15% of patients undergoing cholecystectomy. To date, the ideal management of CBD stones remains controversial. Prospective randomized trials have shown that laparoscopic management of the CBD stones, as a single stage procedure, is the most efficient and cost effective method of treatment. Laparoendoscopic rendezvous has been proposed as an alternative single stage approach. Several studies have shown the effective use of this technique in the treatment of CBD stones by improving patient compliance and clinical results including shorter hospital stay, higher success rate and less cost. The current evidence about the use of this technique presented in this review article is promising and demonstrates the main advantages of the procedure.

  7. Imaging Flash Lidar for Safe Landing on Solar System Bodies and Spacecraft Rendezvous and Docking

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Roback, Vincent E.; Bulyshev, Alexander E.; Brewster, Paul F.; Carrion, William A; Pierrottet, Diego F.; Hines, Glenn D.; Petway, Larry B.; Barnes, Bruce W.; Noe, Anna M.

    2015-01-01

    NASA has been pursuing flash lidar technology for autonomous, safe landing on solar system bodies and for automated rendezvous and docking. During the final stages of the landing from about 1 kilometer to 500 meters above the ground, the flash lidar can generate 3-Dimensional images of the terrain to identify hazardous features such as craters, rocks, and steep slopes. The onboard flight computer can then use the 3-D map of terrain to guide the vehicle to a safe location. As an automated rendezvous and docking sensor, the flash lidar can provide relative range, velocity, and bearing from an approaching spacecraft to another spacecraft or a space station. NASA Langley Research Center has developed and demonstrated a flash lidar sensor system capable of generating 16,000 pixels range images with 7 centimeters precision, at 20 Hertz frame rate, from a maximum slant range of 1800 m from the target area. This paper describes the lidar instrument and presents the results of recent flight tests onboard a rocket-propelled free-flyer vehicle (Morpheus) built by NASA Johnson Space Center. The flights were conducted at a simulated lunar terrain site, consisting of realistic hazard features and designated landing areas, built at NASA Kennedy Space Center specifically for this demonstration test. This paper also provides an overview of the plan for continued advancement of the flash lidar technology aimed at enhancing its performance to meet both landing and automated rendezvous and docking applications.

  8. Planning and scheduling proximity operations for autonomous orbital rendezvous

    E-print Network

    Guerra, Christopher J., 1978-

    2003-01-01

    This thesis develops a mixed integer programming formulation to solve the proximity operations scheduling problem for autonomous orbital rendezvous. The algorithm of this thesis allows the operator to specify planned modes, ...

  9. Apollo experience report: Lunar module landing radar and rendezvous radar

    NASA Technical Reports Server (NTRS)

    Rozas, P.; Cunningham, A. R.

    1972-01-01

    A developmental history of the Apollo lunar module landing and rendezvous radar subsystems is presented. The Apollo radar subsystems are discussed from initial concept planning to flight configuration testing. The major radar subsystem accomplishments and problems are discussed.

  10. STS-134: Rendezvous Pitch Maneuver - Duration: 4 minutes.

    NASA Video Gallery

    On May 18, 2011, space shuttle Endeavour performed the Rendezvous Pitch Maneuver, or "backflip." With Commander Mark Kelly at the helm, Endeavour rotated 360 degrees backward to enable Internationa...

  11. Mission summary: Halley flyby/Tempel-2 rendezvous

    NASA Technical Reports Server (NTRS)

    Atkins, K.

    1979-01-01

    A unique dual-comet flight opportunity exists in mid-1985 which includes flyby of the large and active comet Halley en route to rendezvous with second comet, Tempel-2. This mission will utilize ion propulsion at a modest performance level, based on proven technology. The Project is planned for FY81 start. Launch occurs in July 1985 via the Shuttle/IUS twin stage. Following IUS injection, the ion propulsion stage provides continuous thrust virtually throughout the 3-year flight until the Tempel-2 rendezvous in 1988. En route, a probe is deployed for encounter with Halley about 4 months after launch at a point 73 days before its perihelion. Rendezvous with Tempel-2 occurs about 60 days before the comet's perihelion during the summer of 1988 and continues for about 1 year. Earth will be in favorable relative positions for observing both the flyby and the rendezvous.

  12. Autonomous rendezvous and capture development infrastructure

    NASA Technical Reports Server (NTRS)

    Bryan, Thomas C.

    1991-01-01

    In the development of the technology for autonomous rendezvous and docking, key infrastructure capabilities must be used for effective and economical development. This need involves facility capabilities, both equipment and personnel, to devise, develop, qualify, and integrate ARD elements and subsystems into flight programs. One effective way of reducing technical risks in developing ARD technology is the use of the Low Earth Orbit test facility. Using a reusable free-flying testbed carried in the Shuttle, as a technology demonstration test flight, can be structured to include a variety of sensors, control schemes, and operational approaches. This testbed and flight demonstration concept will be used to illustrate how technologies and facilities at MSFC can be used to develop and prove an ARD system.

  13. Autonomous rendezvous and capture development infrastructure

    NASA Technical Reports Server (NTRS)

    Bryan, Thomas C.; Roe, Fred; Coker, Cindy; Nelson, Pam; Johnson, B.

    1991-01-01

    In the development of the technology for autonomous rendezvous and docking, key infrastructure capabilities must be used for effective and economical development. This involves facility capabilities, both equipment and personnel, to devise, develop, qualify, and integrate ARD elements and subsystems into flight programs. One effective way of reducing technical risks in developing ARD technology is the use of the ultimate test facility, using a Shuttle-based reusable free-flying testbed to perform a Technology Demonstration Test Flight which can be structured to include a variety of additional sensors, control schemes, and operational approaches. This conceptual testbed and flight demonstration will be used to illustrate how technologies and facilities at MSFC can be used to develop and prove an ARD system.

  14. Low Earth Orbit Rendezvous Strategy for Lunar Missions

    NASA Technical Reports Server (NTRS)

    Cates, Grant R.; Cirillo, William M.; Stromgren, Chel

    2006-01-01

    On January 14, 2004 President George W. Bush announced a new Vision for Space Exploration calling for NASA to return humans to the moon. In 2005 NASA decided to use a Low Earth Orbit (LEO) rendezvous strategy for the lunar missions. A Discrete Event Simulation (DES) based model of this strategy was constructed. Results of the model were then used for subsequent analysis to explore the ramifications of the LEO rendezvous strategy.

  15. Scanning laser radar system for rendezvous and docking in space

    NASA Astrophysics Data System (ADS)

    Saito, Hirobumi; Nakatani, Ichiro; Ninomiya, Keiken; Furuya, Akira

    1987-10-01

    A scanning laser radar system for rendezvous and docking in space is being developed. This laser radar system will be utilized in an autonomous satellite retrieval experiment which is planned as one of the future missions to be conducted on Japanese Space Flyer Unit (SFU) in 1990s. Rendezvous and retrieval operation will be automatically performed by on-board instruments. The laser radar system performs ranging, tracking, as well as attitude determination in short range.

  16. Automated Rendezvous and Capture System Development and Simulation for NASA

    NASA Technical Reports Server (NTRS)

    Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

    2004-01-01

    The United States does not have an Automated Rendezvous and Capture Docking (AR&C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. T h i s reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR&C) system for U.S. space vehicles. This A M C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized as the primary navigation sensor on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004. Realtime closed-loop simulations will be performed to validate the improved AR&C systems prior to flight.

  17. Automated rendezvous and capture system development and simulation for NASA

    NASA Astrophysics Data System (ADS)

    Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

    2004-09-01

    The United States does not have an Automated Rendezvous and Capture/Docking (AR&C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. This reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR&C) system for U.S. space vehicles. This AR&C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized as the primary navigation sensor on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004. Realtime closed-loop simulations will be performed to validate the improved AR&C systems prior to flight.

  18. Dynamics and control of escape and rescue from a tumbling spacecraft

    NASA Technical Reports Server (NTRS)

    Kaplan, M. H.

    1972-01-01

    The results of 18 months of investigations are reported. A movable mass control system to convert the tumbling motion of a spacecraft into simple spin was studied along with the optimization techniques for generating displacement profiles for a tumbling asymmetrical body. Equations of motion are discussed for two asymmetrical vehicles with flexible beams and one spacecraft with flexible solar arrays. The characteristics which allow reasonable safety and reliability in bailout are also discussed.

  19. Affect of Shape Abnormality in Foot and Toenail on Tumbling of Aged

    NASA Astrophysics Data System (ADS)

    Yamashita, Kazuhiko; Nomoto, Yohei; Umezawa, Jun; Miyagawa, Haruki; Kawasumi, Masashi; Koyama, Hironori; Saito, Masao

    There is the increasing concern of the society to prevent the tumbling of the aged. The study of the static, as well as dynamic aspects, such as the muscular strength of the lower-limb and the postural stability, should be developed, especially from the viewpoint of the aged. This paper focuses on the external observation of the foot and toenail, as being correlated to the physical functions of the lower-limb against tumbling. The lower-limb functions are evaluated in terms of the 10 m walking time, the toe-gap force and single-foot standing period. The correlation to the personal tumbling experiences is also examined. It is seen that the groups, which exhibit external abnormalities in the foot and the toenail, generally decline in the muscular strength and postural stability. They also have more frequent tumbling experiences and express in their concern of the danger of tumbling. It seems that those shapes abnormalities can indicate, to some extent, the tumbling danger of the aged.

  20. Automated Rendezvous and Capture System Development and Simulation for NASA

    NASA Technical Reports Server (NTRS)

    Roe, Fred D.; Howard, Richard T.; Murphy, Leslie

    2004-01-01

    The United States does not have an Automated Rendezvous and Capture/Docking (AR and C) capability and is reliant on manned control for rendezvous and docking of orbiting spacecraft. This reliance on the labor intensive manned interface for control of rendezvous and docking vehicles has a significant impact on the cost of the operation of the International Space Station (ISS) and precludes the use of any U.S. expendable launch capabilities for Space Station resupply. The Soviets have the capability to autonomously dock in space, but their system produces a hard docking with excessive force and contact velocity. Automated Rendezvous and Capture/Docking has been identified as a key enabling technology for the Space Launch Initiative (SLI) Program, DARPA Orbital Express and other DOD Programs. The development and implementation of an AR&C capability can significantly enhance system flexibility, improve safety, and lower the cost of maintaining, supplying, and operating the International Space Station. The Marshall Space Flight Center (MSFC) has conducted pioneering research in the development of an automated rendezvous and capture (or docking) (AR and C) system for U.S. space vehicles. This AR&C system was tested extensively using hardware-in-the-loop simulations in the Flight Robotics Laboratory, and a rendezvous sensor, the Video Guidance Sensor was developed and successfully flown on the Space Shuttle on flights STS-87 and STS-95, proving the concept of a video- based sensor. Further developments in sensor technology and vehicle and target configuration have lead to continued improvements and changes in AR&C system development and simulation. A new Advanced Video Guidance Sensor (AVGS) with target will be utilized on the Demonstration of Autonomous Rendezvous Technologies (DART) flight experiment in 2004.

  1. The ion drive program - Comet rendezvous issues for SEPS developers

    NASA Technical Reports Server (NTRS)

    Atkins, K. L.

    1979-01-01

    Preliminary steps have been taken in a joint high-priority project between NASA and the European Space Agency, whereby a Solar Electric Propulsion System (SEPS), using ion drive of a 25-30 kilowatt power level, will be utilized for the first time, as part of the Space Transportation System, in powering a probe to be deployed toward Halley's comet in 1985 and a separate spacecraft which will rendezvous with the Temple 2 comet in 1988 and study it for one year. Unlike ballistically-launched vehicles, an unprecedented long-term interaction between the SEPS, the primary source of power and attitude control, and the spacecraft, responsible for data handling (at a rate of 10-120 kilobits per second), and command and telecommunications to earth (requiring capabilities at both X- and S-band frequencies, for dual-frequency navigational tracking), is required, as mission phases alternate between powered flight and science data-taking. Different design sensitivities are presented graphically.

  2. A Monte-Carlo performance analysis of Kalman filter and targeting algorithms for autonomous orbital rendezvous

    E-print Network

    Vaughan, Andrew Thomas, 1979-

    2004-01-01

    Autonomous orbital rendezvous with an orbiting sample (OS) is seen as an enabling technology for a Mars Sample Return (MSR) mission, so several demonstrations have been planned. With CNES cooperation a proposed rendezvous ...

  3. Power-Aware Rendezvous with Shrinking Footprints Hassan Jaleel and Magnus Egerstedt

    E-print Network

    Egerstedt, Magnus

    Power-Aware Rendezvous with Shrinking Footprints Hassan Jaleel and Magnus Egerstedt Abstract, the footprint shrinks as well, and in this paper we propose a controller that solves the rendezvous problem

  4. Soviet automated rendezvous and docking system overview

    NASA Technical Reports Server (NTRS)

    Hinman, Elaine M.; Bushman, David M.

    1991-01-01

    The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing relative positions and attitudes. The active spacecraft has a transponder. From discussions with Soviet engineers, it seems the docking process can be controlled either from the ground or from the active (docking) spacecraft's onboard computer. The unmanned Progress resupply ships regularly dock with the current MIR Space Station. The Soyuz T spacecraft incorporated the IGLA system, and the later Soyuz TM and Progress M Series spacecraft incorporated the KURS. The MIR Complex has both systems installed. The rear port and the KVANT docking port have the IGLA system installed to support earlier Progress ships that use the IGLA. The first Soyuz TM docking occurred in May of 1986, while the first Progress M docked in September of 1989.

  5. Soviet automated rendezvous and docking system overview

    NASA Astrophysics Data System (ADS)

    Hinman, Elaine M.; Bushman, David M.

    The Soviets have been performing automated rendezvous and docking for many years. It has been a reliable mode of resupply and reboost. During the course of the Soviet space program, the autodocking system has evolved. The earlier IGLA system was replaced with the current KURS system. Both systems are radar-based. The variation in strength between antennas is used for computing relative positions and attitudes. The active spacecraft has a transponder. From discussions with Soviet engineers, it seems the docking process can be controlled either from the ground or from the active (docking) spacecraft's onboard computer. The unmanned Progress resupply ships regularly dock with the current MIR Space Station. The Soyuz T spacecraft incorporated the IGLA system, and the later Soyuz TM and Progress M Series spacecraft incorporated the KURS. The MIR Complex has both systems installed. The rear port and the KVANT docking port have the IGLA system installed to support earlier Progress ships that use the IGLA. The first Soyuz TM docking occurred in May of 1986, while the first Progress M docked in September of 1989.

  6. The comet rendezvous asteroid flyby mission

    NASA Technical Reports Server (NTRS)

    Weissman, Paul; Neugebauer, Marcia

    1992-01-01

    The Comet Rendezvous Asteroid Flyby (CRAF) mission was approved for a New Start by the United States Congress in 1989. CRAF will be developed in parallel with the Cassini (Saturn orbiter/Titan probe) mission. The two missions have been combined into a joint program because of the substantial cost savings (approximately $500 M, or greater than 25 percent) which can be realized by using a common spacecraft design, several identical science instruments, a single management team, and a joint ground operations and data handling system for the two missions. CRAF and Cassini will be the first users of the new Mariner Mark 2 spacecraft which has been designed to carry out the next generation of planetary missions to the outer planets and to small bodies. CRAF is a joint mission between the United States, Germany, and Italy. Each partner will provide both engineering hardware and science experiments. Cassini is a joint mission between the United States, Germany, Italy, and the European Space Agency (ESA), with ESA providing the Titan atmospheric entry probe, called Huygens.

  7. Interstellar rendezvous missions employing fission propulsion systems

    NASA Astrophysics Data System (ADS)

    Lenard, Roger X.; Lipinski, Ronald J.

    2000-01-01

    There has been a conventionally held nostrum that fission system specific power and energy content is insufficient to provide the requisite high accelerations and velocities to enable interstellar rendezvous missions within a reasonable fraction of a human lifetime. As a consequence, all forms of alternative mechanisms that are not yet, and may never be technologically feasible, have been proposed, including laser light sails, fusion and antimatter propulsion systems. In previous efforts, [Lenard and Lipinski, 1999] the authors developed an architecture that employs fission power to propel two different concepts: one, an unmanned probe, the other a crewed vehicle to Alpha Centauri within mission times of 47 to 60 years. The first portion of this paper discusses employing a variant of the ``Forward Resupply Runway'' utilizing fission systems to enable both high accelerations and high final velocities necessary for this type of travel. The authors argue that such an architecture, while expensive, is considerably less expensive and technologically risky than other technologically advanced concepts, and, further, provides the ability to explore near-Earth stellar systems out to distances of 8 light years or so. This enables the ability to establish independent human societies which can later expand the domain of human exploration in roughly eight light-year increments even presuming that no further physics or technology breakthroughs or advances occur. In the second portion of the paper, a technology requirement assessment is performed. The authors argue that reasonable to extensive extensions to known technology could enable this revolutionary capability. .

  8. WISE Observations of Rendezvous Mission Candidate Comets

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Bauer, J. M.; Fernandez, Y. R.; Mainzer, A. K.; Walker, R. G.; Meech, K. J.; Grav, T.; Weissman, P. R.; Kramer, E.; Stevenson, R.

    2012-10-01

    In 1992, Osip et al. wrote: "Several comet flyby and/or rendezvous missions are currently being planned, for which supporting groundbased data from previous apparitions should prove useful. Here, we discuss groundbased narrowband photometry obtained over the last 15 years for nine candidate comets, five of which have been observed on multiple apparitions -- we derive limits on the size of each cometary nucleus. In order to facilitate spacecraft mission planning, we also present molecular abundance ratios, note variations in cometary activity as a function of orbital position and between apparitions, and note the overall degree of dustiness. A detailed analysis of the characteristics of these nine viable mission candidates will provide necessary information for prioritizing targets for any future missions." In this work, we update Osip et al.'s 1992 work using recent photometric infrared observations of the best candidate comet spacecraft targets observed by WISE and other (IRAS, MSX, ISO, Spitzer) infrared space telescopes. The comets studied include 2P/Encke, 9P/Tempel 1, 10P Tempe1 2, 19P/Borrelly, 22P/Kopff, 67P/Churyumov-Gerasimenko, 81P/Wild, 103P/Hartley 2, 107P/Wilson-Harrington. We present imagery, photometry, and temporal trend data, and derived estimates of the dust mass, spatial distribution, albedo/emissivity, and PSD for each comet.

  9. Expert System Issues In Automated, Autonomous Space Vehicle Rendezvous

    NASA Astrophysics Data System (ADS)

    Goodwin, Mary Ann; Bochsler, Daniel C.

    1987-05-01

    The Rendezvous Expert (RENEX) program simulates autonomous rendezvous and proximity operations during spaceflight for selected active vehicles and target vehicles. Space Shuttle mission flight rules were used as the basis for developing the knowledge base for trajectory planning/replanning and monitoring. Emphasis was on so-called "day of rendezvous" activities. The RENEX expert system software simulates real-time system monitoring as well as trajectory planning and software control functions. Conventional software simulates the vehicle guidance, navigation, and control functions. RENEX was developed to support streamlining operations for the Space Shuttle and Space Station programs and to aid definition of mission requirements for the autonomous portions of rendezvous for the Mars Surface Sample Return and Comet Nucleus Sample Return unmanned missions. The goal was to develop expert system technology which could be applied to operational decision support systems and/or to automating appropriate vehicle operations. The expert system and the insight it has provided into the development and the use of expert systems to achieve greater automation of rendezvous operations is discussed.

  10. Spacecraft rendezvous operational considerations affecting vehicle systems design and configuration

    NASA Astrophysics Data System (ADS)

    Prust, Ellen E.

    One lesson learned from Orbiting Maneuvering Vehicle (OMV) program experience is that Design Reference Missions must include an appropriate balance of operations and performance inputs to effectively drive vehicle systems design and configuration. Rendezvous trajectory design is based on vehicle characteristics (e.g., mass, propellant tank size, and mission duration capability) and operational requirements, which have evolved through the Gemini, Apollo, and STS programs. Operational constraints affecting the rendezvous final approach are summarized. The two major objectives of operational rendezvous design are vehicle/crew safety and mission success. Operational requirements on the final approach which support these objectives include: tracking/targeting/communications; trajectory dispersion and navigation uncertainty handling; contingency protection; favorable sunlight conditions; acceptable relative state for proximity operations handover; and compliance with target vehicle constraints. A discussion of the ways each of these requirements may constrain the rendezvous trajectory follows. Although the constraints discussed apply to all rendezvous, the trajectory presented in 'Cargo Transfer Vehicle Preliminary Reference Definition' (MSFC, May 1991) was used as the basis for the comments below.

  11. Rendezvous and Proximity Operations of the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Goodman, John L.

    2005-01-01

    Space Shuttle rendezvous missions present unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations, and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading, and contamination concerns. These issues, along with limited reaction control system propellant in the Shuttle nose, drove a change from the legacy Gemini/Apollo coelliptic profile to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions, and crew exchange, assembly and replenishment flights to Mir and to the International Space Station drove further profile and piloting technique changes. These changes included new proximity operations, relative navigation sensors, and new computer generated piloting cues. However, the Shuttle's baseline rendezvous navigation system has not required modification to place the Shuttle at the proximity operations initiation point for all rendezvous missions flown.

  12. Development of control and autonomy algorithms for docking to complex tumbling satellites

    E-print Network

    Fejzi?, Amer

    2008-01-01

    The capability of automated rendezvous and docking is a key enabling technology for many government and commercial space programs. Future space systems will employ a high level of autonomy to acquire, repair, refuel, and ...

  13. MultiSensor Testing for Automated Rendezvous and Docking Sensor Testing at the Flight Robotics Lab

    Microsoft Academic Search

    Linda L. Brewster; Richard T. Howard; A. S. Johnston; C. Carrington; J. D. Mitchell; S. P. Cryan

    2008-01-01

    The exploration systems architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in low earth orbit (LEO) and in low lunar orbit (LLO). Uncrewed spacecraft must perform automated and\\/or autonomous rendezvous, proximity operations and docking operations (commonly known as AR&D). The crewed missions may also perform rendezvous and docking operations and may require different

  14. Navigation requirements for rendezvous with the satellites of Mars.

    NASA Technical Reports Server (NTRS)

    Satin, A. L.

    1972-01-01

    Navigation aspects of a rendezvous mission to Deimos (the outer satellite of Mars) were examined using a modified Viking Monte Carlo error analysis program. Rendezvous is initiated by two-impulse transfer from an observation orbit cotangent with the orbit of Deimos. Television sightings of the satellite against a star background will allow a 20 km closest approach radius (R99) 99% of the time. This is well within the 100 km range of the terminal rendezvous radar. An additional delta-V capability of about 100 m/sec (above the nominal) must be allocated to account for the statistical nature of the mission. This delta-V requirement was found to be very sensitive to the level of satellite ephemeris error and maneuver execution error. The R99 on the other hand, is sensitive to the in-orbit DSN error and the maneuver execution error.

  15. Endoscopic retrograde cholangiopancreatography with rendezvous cannulation reduces pancreatic injury

    PubMed Central

    Swahn, Fredrik; Regnér, Sara; Enochsson, Lars; Lundell, Lars; Permert, Johan; Nilsson, Magnus; Thorlacius, Henrik; Arnelo, Urban

    2013-01-01

    AIM: To examine whether rendezvous endoscopic retrograde cholangiopancreatography (ERCP) is associated with less pancreatic damage, measured as leakage of proenzymes, than conventional ERCP. METHODS: Patients (n = 122) with symptomatic gallstone disease, intact papilla and no ongoing inflammation, were prospectively enrolled in this case-control designed study. Eighty-one patients were subjected to laparoscopic cholecystectomy and if intraoperative cholangiography suggested common bile duct stones (CBDS), rendezvous ERCP was performed intraoperatively (n = 40). Patients with a negative cholangiogram constituted the control group (n = 41). Another 41 patients with CBDS, not subjected to surgery, underwent conventional ERCP. Pancreatic proenzymes, procarboxypeptidase B and trypsinogen-2 levels in plasma, were analysed at 0, 4, 8 and 24 h. The proenzymes were determined in-house with a double-antibody enzyme linked immunosorbent assay. Pancreatic amylase was measured by an enzymatic colourimetric modular analyser with the manufacturer’s reagents. All samples were blinded at analysis. RESULTS: Post ERCP pancreatitis (PEP) occurred in 3/41 (7%) of the patients cannulated with conventional ERCP and none in the rendezvous group. Increased serum levels indicating pancreatic leakage were significantly higher in the conventional ERCP group compared with the rendezvous ERCP group regarding pancreatic amylase levels in the 4- and 8-h samples (P = 0.0015; P = 0.03), procarboxypeptidase B in the 4- and 8-h samples (P < 0.0001; P < 0.0001) and trypsinogen-2 in the 24-hour samples (P = 0.03). No differences in these markers were observed in patients treated with rendezvous cannulation technique compared with patients that underwent cholecystectomy alone (control group). Post procedural concentrations of pancreatic amylase and procarboxypeptidase B were significantly correlated with pancreatic duct cannulation and opacification. CONCLUSION: Rendezvous ERCP reduces pancreatic enzyme leakage compared with conventional ERCP cannulation technique. Thus, laparo-endoscopic technique can be recommended with the ambition to minimise the risk for post ERCP pancreatitis. PMID:24106403

  16. Apollo-Lunar Orbital Rendezvous Technique

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Apollo-Lunar Orbital Rendezvous Technique. The film shows artists rendition of the spacecrafts, boosters, and flight of the Apollo lunar missions. The Apollo spacecraft will consist of three modules: the manned Command Module; the Service Module, which contains propulsion systems; and the Lunar Excursion Module (LEM) to carry astronauts to the moon and back to the Command and Service Modules. The spacecraft will be launched via a three-stage Saturn booster. The first stage will provide 7.5 million pounds of thrust from five F-1 engines for liftoff and initial powered flight. The second stage will develop 1 million pounds of thrust from five J-2 engines to boost the spacecraft almost into Earth orbit. Immediately after ignition of the second stage, the Launch Escape System will be jettisoned. A single J-2 engine in the S4B stage will provide 200,000 pounds of thrust to place the spacecraft in an earth parking orbit. It also will be used to propel the spacecraft into a translunar trajectory, then it will separate from the Apollo Modules. Onboard propulsion systems will be used to insert the spacecraft into lunar orbit. Two astronauts will enter the LEM, which will separate from the command and service modules. The LEM will go into elliptical orbit and prepare for landing. The LEM will lift off of the Moon's surface to return to the Command and Service Modules, and most likely be left in lunar orbit. After leaving the Moon's orbit, and shortly before entering Earth's orbit, the Service Module will be ejected. The Command Module will be oriented for reentry into the Earth's atmosphere. A drogue parachute will deploy at approximately 50,000 feet, followed by the main parachute system for touchdown. [Entire movie available on DVD from CASI as Doc ID 20070030988. Contact help@sti.nasa.gov

  17. Robust H? Control for Spacecraft Rendezvous with a Noncooperative Target

    PubMed Central

    Wu, Shu-Nan; Zhou, Wen-Ya; Tan, Shu-Jun; Wu, Guo-Qiang

    2013-01-01

    The robust H? control for spacecraft rendezvous with a noncooperative target is addressed in this paper. The relative motion of chaser and noncooperative target is firstly modeled as the uncertain system, which contains uncertain orbit parameter and mass. Then the H? performance and finite time performance are proposed, and a robust H? controller is developed to drive the chaser to rendezvous with the non-cooperative target in the presence of control input saturation, measurement error, and thrust error. The linear matrix inequality technology is used to derive the sufficient condition of the proposed controller. An illustrative example is finally provided to demonstrate the effectiveness of the controller. PMID:24027446

  18. A Study on Rendezvous Docking Control of the HOPE

    NASA Astrophysics Data System (ADS)

    Hashizume, Yuji; Imado, Fumiaki; Murota, Akira

    A study on rendezvous docking control of the HOPE is presented. The HOPE is the Japanese version of unmanned space shuttle, which requires the automatic rendezvous docking guidance algorithm. In this paper, the thruster combination algorithm is implemented by using linear programming (LP) method for minimum fuel consumption. The automatic guidance algorithms for three approaching phases are developed. The numerical simulation by these algorithms showed good result. The thruster combination algorithm by LP, the determination algorithm of the thruster firing timing by C-W-Hill’s equation, and the technique for implementing the simulation are explained in detail.

  19. Automatic rendezvous and capture system development in a manned environment

    NASA Astrophysics Data System (ADS)

    Kachmar, Peter M.; Jackson, William L.

    This paper presents the development of a 'Phase One' AR&C system capability as a logical outgrowth of Rendezvous and Proximity Operations (R&PO) system development for manned space programs. The continuity of the approach to R&PO across the Apollo, Skylab, Apollo-Soyuz, and Shuttle programs is traced and lessons learned which are applicable to AR&C discussed. Use of the Shuttle as a test bed for Automatic Rendezvous and Capture capabilities and technology demonstrations is discussed. A status of the current Phase One System design and brief overview of its capabilities is presented.

  20. Laser space rendezvous and docking system study continuation

    NASA Technical Reports Server (NTRS)

    Adelman, S.; Heynau, H.; Levinson, S.; Weindling, F.

    1977-01-01

    Investigations were made of a configuration for a spaceborne laser radar (ladar) to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. An analysis was completed of laser phase locking techniques, while experimental verification was made of pulse repetition frequency and resonant scanning control loops. Data measurements on a satellite mock-up were also made. The investigation supports the original contention that a rendezvous and docking ladar can be configured to offer a cost effective and reliable solution to envisioned space missions.

  1. Electron paramagnetic resonance studies of slowly tumbling vanadyl spin probes in nematic liquid crystals

    NASA Technical Reports Server (NTRS)

    Bruno, G. V.; Harrington, J. K.; Eastman, M. P.

    1978-01-01

    An analysis of EPR line shapes by the method of Polnaszek, Bruno, and Freed is made for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals. The use of typical vanadyl complexes as spin probes for nematic liquid crystals is shown to simplify the theoretical analysis and the subsequent interpretation. Rotational correlation times tau and orientational ordering parameters S sub Z where slow tumbling effects are expected to be observed in vanadyl EPR spectra are indicated in a plot. Analysis of the inertial effects on the probe reorientation, which are induced by slowly fluctuating torque components of the local solvent structure, yield quantitative values for tau and S sub Z. The weakly ordered probe VOAA is in the slow tumbling region and displays these inertial effects throughout the nematic range of BEPC and Phase V. VOAA exhibits different reorientation behavior near the isotropic-nematic transition temperature than that displayed far below this transition temperature.

  2. Effect of Different Tumbling Marination Treatments on the Quality Characteristics of Prepared Pork Chops

    PubMed Central

    Gao, Tian; Li, Jiaolong; Zhang, Lin; Jiang, Yun; Ma, Ruixue; Song, Lei; Gao, Feng; Zhou, Guanghong

    2015-01-01

    The effect of different tumbling marination treatments (control group, CG; conventional static marination, SM; vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) on the quality characteristics of prepared pork chops was investigated under simulated commercial conditions. The CT treatment increased (p<0.05) the pH value, b* value, product yield, tenderness, overall flavor, sensory juiciness and overall acceptability in comparison to other treatments for prepared boneless pork chops. The CT treatment decreased (p<0.05) cooking loss, shear force value, hardness, gumminess and chewiness compared with other treatments. In addition, CT treatment effectively improved springiness and sensory color more than other treatments. However, IT treatment achieved the numerically highest (p<0.05) L* and a* values. These results suggested that CT treatment obtained the best quality characteristics of prepared pork chops and should be adopted as the optimal commercial processing method for this prepared boneless pork chops. PMID:25557823

  3. Operator Monitoring and Support System for Rendezvous and Docking

    Microsoft Academic Search

    Wigbert Fehse; Guillermo Ortega

    Rendezvous and docking operations of unmanned supply vehicles, e.g. presently Progress within the Russian Mir Space Station scenario, and later within the International Space Station scenario the Russian Progress, the European ATV and the Japanese HTV, are automatic but not fully autonomous. Safety of crew, vehicle security of the target station and mission success assurance require monitoring and interaction capabilities

  4. Performance of Concurrent Rendezvous Systems with Complex Pipeline Structures

    E-print Network

    Woodside, C. Murray

    Performance of Concurrent Rendezvous Systems with Complex Pipeline Structures Real February 11, 1998 Abstract The term ``complex pipeline'' describes a set of tasks which process incoming data in a sequence, like a pipeline, but have various kinds of parallel execution steps coupled

  5. Total solar irradiance fluctuation effects on sailcraft-Mars rendezvous

    Microsoft Academic Search

    Giovanni Vulpetti

    2011-01-01

    This paper is the second one of a research line whereupon the variations of the total solar irradiance are explicitly included in a large high-precision computer code for sailcraft trajectory optimization. Sailcraft-Mars rendezvous has been chosen for studying such effects. It turns out that irradiance-fluctuation perturbations are large in this trajectory type.

  6. Test Results for the Automated Rendezvous and Capture System

    NASA Technical Reports Server (NTRS)

    Cruzen, Craig; Dabney, Richard; Lomas, James

    1999-01-01

    The Automated Rendezvous and Capture (AR&C) system was designed and tested at NASA's Marshall Space Flight Center (MSFC) to demonstrate technologies and mission strategies for automated rendezvous and docking of spacecraft in Earth orbit, The system incorporates some of the latest innovations in Global Positioning, System space navigation, laser sensor technologies and automated mission sequencing algorithms. The system's initial design and integration was completed in 1998 and has undergone testing at MSFC. This paper describes the major components of the AR&C system and presents results from the official system tests performed in MSFC's Flight Robotics Laboratory with digital simulations and hardware in the loop tests. The results show that the AR&C system can safely and reliably perform automated rendezvous and docking missions in the absence of system failures with 100 percent success. When system failures are included, the system uses its automated collision avoidance maneuver logic to recover in a safe manner. The primary objective of the AR&C project is to prove that by designing a safe and robust automated system, mission operations cost can be reduced by decreasing the personnel required for mission design, preflight planning and training required for crewed rendezvous and docking missions.

  7. Multiple NEO Rendezvous, Reconnaissance and In Situ Exploration

    NASA Astrophysics Data System (ADS)

    Klaus, K.; Elsperman, M. S.; Smith, D. B.; Cook, T. S.

    2011-03-01

    We propose a two spacecraft rendezvous with multiple NEOs. A two spacecraft mission mimics architecture for human explorers to use a mother ship to get from Earth to the NEO and a small body lander for in situ investigation on or close to the NEO.

  8. Optimal analytic rendezvous using Clohessy-Wiltshire equations

    NASA Technical Reports Server (NTRS)

    Jezewski, D. J.; Donaldson, J. D.

    1978-01-01

    The optimal solution time that minimizes the sum of the two applied impulses necessary to rendezvous is obtained analytically for the Clohessy-Wiltshire equations with a linear gravity model assumption. A plume impingement inequality constraint on the solution is examined, and an optimal policy is developed. Numerical tests are conducted to verify the analysis and to illustrate the optimal solution algorithm.

  9. Rendezvous radar modification and evaluation. [for space shuttles

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The purpose of this effort was to continue the implementation and evaluation of the changes necessary to add the non-cooperative mode capability with frequency diversity and a doppler filter bank to the Apollo Rendezvous Radar while retaining the cooperative mode capability.

  10. Spectrum Sharing with Rotating Radar: Implications for Cognitive Radio Rendezvous

    E-print Network

    Buehrer, R. Michael

    Spectrum Sharing with Rotating Radar: Implications for Cognitive Radio Rendezvous Jeffrey D. Poston in time & frequency. Even prior work specifically on sharing with radar systems typically proposes switching to another frequency upon detection of radar activity. An opportunity exists for a more

  11. The Space Shuttle rendezvous radar target acquisition performance computer simulation

    Microsoft Academic Search

    H. G. Magnusson

    1982-01-01

    A Monte Carlo computer simulation model was developed to estimate the target acquisition performance of the Space Shuttle Ku-Band Rendezvous Radar. The philosophy behind the development of the simulation was to achieve a high fidelity model of the acquisition process while maintaining reasonable computing speed so that a large number of representative acquisition situations could be tested. This paper provides

  12. KU-Band rendezvous radar performance computer simulation model

    Microsoft Academic Search

    J. W. Griffin

    1980-01-01

    The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation\\/radar simulation

  13. Ku-Band rendezvous radar performance computer simulation model

    Microsoft Academic Search

    H. G. Magnusson; M. F. Goff

    1984-01-01

    All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total

  14. Stereo-based tracking system for automated rendezvous and capture

    Microsoft Academic Search

    Alan T. Smith; Timothy E. Fisher

    1993-01-01

    In the past, NASA tracking systems which provided range and bearing to targets have primarily been radar based. Advanced projects such as unmanned missions to the moon and Mars need automated rendezvous and capture (AR&C) to reduce operating costs and improve mission reliability. In the Tracking Techniques Branch at Johnson Space Center we are investigating the feasibility of a stereo

  15. Autonomous rendezvous and feature detection system using TV imagery

    NASA Technical Reports Server (NTRS)

    Rice, R. B., Jr.

    1977-01-01

    Algorithms and equations are used for conversion of standard television imaging system information into directly usable spatial and dimensional information. System allows utilization of spacecraft imagery system as sensor in application to operations such as deriving spacecraft steering signal, tracking, autonomous rendezvous and docking and ranging.

  16. PERFORMANCE EVALUATION OF RENDEZVOUS USING MODEL PREDICTIVE CONTROL

    E-print Network

    How, Jonathan P.

    of spacecraft rendezvous. This demonstrates two key features of the new MPC method. Firstly, its abil- ity suffers. The new formulation extends previous work [2, 22] in which a variable horizon was used to achieve How ABSTRACT A new form of Model Predictive Control (MPC) is presented. It is shown to guarantee

  17. Let's Rendezvous: Application of Location-Aware Computing

    E-print Network

    Toronto, University of

    Let's Rendezvous: Application of Location-Aware Computing David Dearman EDGE Lab Faculty of Computer Science Dalhousie University, Canada dearman@cs.dal.ca POSITION STATEMENT Our current project will be available at the time of the `Applications of Location-Aware Computing' workshop. BIOGRAPHY David Dearman

  18. Angles-only navigation for autonomous orbital rendezvous

    Microsoft Academic Search

    David C. Woffinden

    2008-01-01

    The proposed thesis of this dissertation has both a practical element and theoretical component which aim to answer key questions related to the use of angles-only navigation for autonomous orbital rendezvous. The first and fundamental principle to this work argues that an angles-only navigation filter can determine the relative position and orientation (pose) between two spacecraft to perform the necessary

  19. Long range sensor for rendezvous and docking missions

    NASA Astrophysics Data System (ADS)

    Losquadro, G.

    1987-11-01

    Configuration, characteristics, and performance of a long range sensor operating with spread spectrum modulation and using a lobe switching sensor, for bearing measurements, installed on the chaser for rendezvous and docking are presented. The target is considered to have a transponder that can be transparent or a demod/remod repeater. The high accuracy required of the sensor imposes stringent equipment tolerances.

  20. Design and fabrication of an autonomous rendezvous and docking sensor using off-the-shelf hardware

    NASA Technical Reports Server (NTRS)

    Grimm, Gary E.; Bryan, Thomas C.; Howard, Richard T.; Book, Michael L.

    1991-01-01

    NASA Marshall Space Flight Center (MSFC) has developed and tested an engineering model of an automated rendezvous and docking sensor system composed of a video camera ringed with laser diodes at two wavelengths and a standard remote manipulator system target that has been modified with retro-reflective tape and 830 and 780 mm optical filters. TRW has provided additional engineering analysis, design, and manufacturing support, resulting in a robust, low cost, automated rendezvous and docking sensor design. We have addressed the issue of space qualification using off-the-shelf hardware components. We have also addressed the performance problems of increased signal to noise ratio, increased range, increased frame rate, graceful degradation through component redundancy, and improved range calibration. Next year, we will build a breadboard of this sensor. The phenomenology of the background scene of a target vehicle as viewed against earth and space backgrounds under various lighting conditions will be simulated using the TRW Dynamic Scene Generator Facility (DSGF). Solar illumination angles of the target vehicle and candidate docking target ranging from eclipse to full sun will be explored. The sensor will be transportable for testing at the MSFC Flight Robotics Laboratory (EB24) using the Dynamic Overhead Telerobotic Simulator (DOTS).

  1. Effects of soy sauce on physicochemical and textural properties of tumbled chicken breast.

    PubMed

    Kim, H W; Hwang, K E; Song, D H; Kim, Y J; Lim, Y B; Choi, J H; Choi, Y S; Kim, H Y; Kim, C J

    2014-03-01

    The objective of this study was to evaluate the effects of soy sauce on the physicochemical and textural properties of tumbled chicken breasts. Chicken breasts marinated with distilled water (Con), 4% NaCl solution, 4% NaCl and lactic acid solution (pH 4.9), and soy sauce solution (4% salt concentration and pH 4.9) were vacuum tumbled at 3°C for 60 min. The chicken breast marinated with soy sauce solution showed lower lightness and higher redness and yellowness due to the color of the soy sauce. The acidic marinades led to a decrease in pH value of tumbled chicken breast. The acidic marinades increased collagen solubility of sample compared with 4% NaCl solution, resulting in decreased shear force. Water-holding capacity, marination and cooking yields, and solubility of myofibrillar proteins were mainly affected by the presence of salt in the marinade, rather than by pH alternation. Our results suggested that soy sauce marination can improve the tenderness of tumbled chicken breast. PMID:24604862

  2. Level of decontamination after washing textiles at 60°C or 70°C followed by tumble drying

    PubMed Central

    Tano, Eva; Melhus, Åsa

    2014-01-01

    Background Several major outbreaks in healthcare facilities have occurred with the emergence of multi-resistant bacteria. A possible route for dissemination is the hospital textiles and inadequate laundering of them. The aim of this study was to develop an easy-to-use method for simulating the laundering process of hospital textiles, and thereafter apply the method when evaluating the decontaminating efficacy of two different washing temperatures. Methods The laundering process, including tumble drying, took place at two professional laundries. Enterococcus faecium was used as bioindicator. Results The results showed that a lowering of the washing temperature from 70°C to 60°C did not affect the decontamination efficacy; the washing cycle alone reduced the number of bacteria with 3–5 log10 CFU, whereas the following tumble drying reduced the bacterial numbers with another 3–4 log10 CFU, yielding the same final result independent of washing temperature. Without tumble drying, there was an obvious risk of adding non-fermenting gram-negative bacteria to the fabric. These bacteria originated from the washing cycle. Conclusion A simple method to simulate hospital laundering was developed. To save energy, it is possible to use a washing temperature of 60°C, but the washing cycle should be followed by tumble drying, and the whole laundering process needs to be monitored to maintain sufficient textile hygiene. PMID:25413829

  3. Preschool Teachers' Perceptions of Rough and Tumble Play vs. Aggression in Preschool-Aged Boys

    ERIC Educational Resources Information Center

    DiCarlo, Cynthia F.; Baumgartner, Jennifer; Ota, Carrie; Jenkins, Charlene

    2015-01-01

    Rough and tumble play has been found to be positive for physical, social and cognitive development; it is often erroneously misinterpreted as aggression and generally stopped by preschool teachers. The current study sought to examine the relationship between teacher training and education and judgements about aggression in children. Ninety-four…

  4. Is Father-Child Rough-and-Tumble Play Associated with Attachment or Activation Relationships?

    ERIC Educational Resources Information Center

    Paquette, Daniel; Dumont, Caroline

    2013-01-01

    The activation relationship theory, primarily focused on parental stimulation of risk-taking along with parental control during exploration, predicts that boys will be activated more than girls by their fathers. This theory may explain why fathers engage in rough-and-tumble play (RTP) with children more frequently than mothers, especially with…

  5. GYMNASTICS LESSONS Whether you want to learn how to tumble, get some exercise, or

    E-print Network

    Beex, A. A. "Louis"

    GYMNASTICS LESSONS Whether you want to learn how to tumble, get some exercise, or just have fun will be practiced with females and all men's events will be practiced with males. PRIVATE LESSONS Designed lessons offer an excellent opportunity to explore your potential. These classes may be taken in addition

  6. Enchanted rendezvous: John C. Houbolt and the genesis of the lunar-orbit rendezvous concept

    NASA Technical Reports Server (NTRS)

    Hansen, James R.

    1995-01-01

    This is the fourth publication of the 'Monographs in Aerospace History' series, prepared by the NASA History Office. These publications are intended to be tightly focused in terms of subject, relatively short in length, and reproduced to allow timely and broad dissemination to researchers in aerospace history. This publication details the arguments of John C. Houbolt, an engineer at the Langley Research Center in Hampton, Virginia, in his 1961-1962 campaign to support the lunar-orbit rendezvous (LOR). The LOR was eventually selected during Project Apollo as the method of flying to the Moon, landing on the surface, and returning to Earth. The LOR opted to send the entire lunar spacecraft up in one launch, enter into the lunar orbit, and dispatch a small lander to the lunar surface. It was the simplest of the various methods, both in terms of development and operational costs, but it was risky. There was no room for error or the crew could not get home; and the more difficult maneuvers had to be done when the spacecraft was committed to a circumlunar flight. Houbolt was one of the most vocal people supporting the LOR.

  7. Effect of Different Tumbling Marination Methods and Time on the Water Status and Protein Properties of Prepared Pork Chops.

    PubMed

    Gao, Tian; Li, Jiaolong; Zhang, Lin; Jiang, Yun; Yin, Maowen; Liu, Yang; Gao, Feng; Zhou, Guanghong

    2015-07-01

    The combined effect of tumbling marination methods (vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) and effective tumbling time (4, 6, 8, and 10 h) on the water status and protein properties of prepared pork chops was investigated. Results showed that regardless of tumbling time, CT method significantly decreased the muscle fiber diameter (MD) and significantly increased the total moisture content, product yield, salt soluble proteins (SSP) solubility, immobilized water component (p<0.05) compared with IT method. With the effective tumbling time increased from 4 h to 10 h, the fat content and the MD were significantly decreased (p<0.05), whereas the SSP solubility of prepared pork chops increased firstly and then decreased. Besides, an interactive effect between CT method and effective tumbling time was also observed for the chemical composition and proportion of immobilized water (p<0.05). These results demonstrated that CT method of 8 h was the most beneficial for improving the muscle structure and water distribution status, increasing the water-binding capacity and accelerating the marinade efficiency of pork chops; and thus, it should be chosen as the most optimal treatment method for the processing production of prepared pork chops. PMID:26104408

  8. Effect of Different Tumbling Marination Methods and Time on the Water Status and Protein Properties of Prepared Pork Chops

    PubMed Central

    Gao, Tian; Li, Jiaolong; Zhang, Lin; Jiang, Yun; Yin, Maowen; Liu, Yang; Gao, Feng; Zhou, Guanghong

    2015-01-01

    The combined effect of tumbling marination methods (vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) and effective tumbling time (4, 6, 8, and 10 h) on the water status and protein properties of prepared pork chops was investigated. Results showed that regardless of tumbling time, CT method significantly decreased the muscle fiber diameter (MD) and significantly increased the total moisture content, product yield, salt soluble proteins (SSP) solubility, immobilized water component (p<0.05) compared with IT method. With the effective tumbling time increased from 4 h to 10 h, the fat content and the MD were significantly decreased (p<0.05), whereas the SSP solubility of prepared pork chops increased firstly and then decreased. Besides, an interactive effect between CT method and effective tumbling time was also observed for the chemical composition and proportion of immobilized water (p<0.05). These results demonstrated that CT method of 8 h was the most beneficial for improving the muscle structure and water distribution status, increasing the water-binding capacity and accelerating the marinade efficiency of pork chops; and thus, it should be chosen as the most optimal treatment method for the processing production of prepared pork chops. PMID:26104408

  9. Mission options for rendezvous with the most accessible Near-Earth Asteroid - 1989 ML

    NASA Technical Reports Server (NTRS)

    Mcadams, Jim V.

    1992-01-01

    The recent discovery of the Amor-class 1989 ML, the most accessible known asteroid for minimum-energy rendezvous missions, has expedited the search for frequent, low-cost Near-Earth Asteroid rendezvous and round-trip missions. This paper identifies trajectory characteristics and assesses mass performance for low Delta V ballistic rendezvous opportunities to 1989 ML during the period 1996-2010. This asteroid also offers occasional unique extended mission opportunities, such as the lowest known Delta V requirement for any asteroid sample return mission as well as pre-rendezvous asteroid flyby and post-rendezvous comet flyby opportunities requiring less than 5.25 km/sec total Delta V. This paper also briefly comments concerning mission opportunities for asteroid 1991 JW, which recently replaced other known asteroids as the most accessible Near-Earth Asteroid for fast rendezvous and round-trip missions.

  10. Automated rendezvous and docking sensor testing at the flight robotics laboratory

    Microsoft Academic Search

    Richard T. Howard; Marlin L. Williamson; Albert S. Johnston; Linda L. Brewster; Jennifer D. Mitchell; Scott P. Cryan; David Strack; Kevin Key

    2007-01-01

    The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and\\/or autonomous rendezvous, proximity operations and docking operations (commonly known as Automated Rendezvous and Docking, (AR&D).) The crewed versions of the spacecraft may also perform AR&D,

  11. AUTONOMOUS AND ROBUST RENDEZVOUS GUIDANCE ON ELLIPTICAL ORBIT SUBJECT TO J 2 PERTURBATION

    Microsoft Academic Search

    Emmanuel GOGIBUS; Hervé CHARBONNEL; Patrick DELPY

    Until recently, the developed guidance algorithms for rendezvous were only able to deal with targets placed on circular or quasi-circular o rbits. This is typically the case of the far rendezvous automatic on-board guidance of ATV (vehicle developed under ESA responsibility, with Astrium Space Transportation as prime contract or, that successfully performed an AR&D (Automated Rendezvous and Docking) in April

  12. Automated Rendezvous and Docking Sensor Testing at the Flight Robotics Laboratory

    Microsoft Academic Search

    J. D. Mitchell; S. P. Cryan; D. Strack; L. L. Brewster; M. J. Williamson; R. T. Howard; A. S. Johnston

    2007-01-01

    The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and\\/or autonomous rendezvous, proximity operations and docking operations (commonly known as Automated Rendezvous and Docking, AR&D). The crewed versions may also perform AR&D, possibly with a

  13. Genetic algorithm based fuzzy control of spacecraft autonomous rendezvous

    NASA Technical Reports Server (NTRS)

    Karr, C. L.; Freeman, L. M.; Meredith, D. L.

    1990-01-01

    The U.S. Bureau of Mines is currently investigating ways to combine the control capabilities of fuzzy logic with the learning capabilities of genetic algorithms. Fuzzy logic allows for the uncertainty inherent in most control problems to be incorporated into conventional expert systems. Although fuzzy logic based expert systems have been used successfully for controlling a number of physical systems, the selection of acceptable fuzzy membership functions has generally been a subjective decision. High performance fuzzy membership functions for a fuzzy logic controller that manipulates a mathematical model simulating the autonomous rendezvous of spacecraft are learned using a genetic algorithm, a search technique based on the mechanics of natural genetics. The membership functions learned by the genetic algorithm provide for a more efficient fuzzy logic controller than membership functions selected by the authors for the rendezvous problem. Thus, genetic algorithms are potentially an effective and structured approach for learning fuzzy membership functions.

  14. Rendezvous and Proximity Operations of the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Goodman, John L.

    2005-01-01

    Space Shuttle rendezous missions presented unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading and contamination concerns. These issues, along with limited forward reaction control system propellant, drove a change from the Gemimi/Apollo coelliptic profile heritage to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions and crew exchange, assembly and replinishment flights to Mir and to the International Space Station drove further profile and piloting technique changes, including new relative navigation sensors and new computer generated piloting cues.

  15. Apollo experience report: Evolution of the rendezvous-maneuver plan for the lunar-landing missions

    NASA Technical Reports Server (NTRS)

    Alexander, J. D.; Becker, R. W.

    1973-01-01

    The evolution of the nominal rendezvous-maneuver plan for the lunar landing missions is presented along with a summary of the significant development for the lunar module abort and rescue plan. A general discussion of the rendezvous dispersion analysis that was conducted in support of both the nominal and contingency rendezvous planning is included. Emphasis is placed on the technical developments from the early 1960's through the Apollo 15 mission (July to August 1971), but pertinent organizational factors also are discussed briefly. Recommendations for rendezvous planning for future programs relative to Apollo experience also are included.

  16. Using advanced industrial robotics for spacecraft Rendezvous and Docking simulation

    Microsoft Academic Search

    Toralf Boge; Ou Ma

    2011-01-01

    One of the most challenging and risky missions for spacecraft is to perform Rendezvous and Docking (RvD) autonomously in space. To ensure a safe and reliable operation, such a mission must be carefully designed and thoroughly verified before a real space mission can be launched. This paper describes a new, robotics-based, hardware-in-the-loop RvD simulation facility which uses two industrial robots

  17. Deep Interior: Multiple-Rendezvous Prospecting of NEOs

    Microsoft Academic Search

    R. Y. Kakuda; E. Asphaug; M. J. S. Belton; S. Gulkis; W. F. Huebner

    2000-01-01

    This is an international multiple-rendezvous mission designed to prospect the deep interior and subsurface geophysical properties of diverse near-Earth objects, using reflection radar tomography, imaging, gravity, and explosions. What we learn will greatly influence future missions and guide strategies for the diversion, disruption, or utilization of potentially hazardous objects. Deep Interior. Low-frequency radar to determine internal variations of complex permittivity

  18. The Near-Earth Asteroid Rendezvous Laser Altimeter

    Microsoft Academic Search

    T. D. Cole; M. T. Boies; A. S. El-Dinary; A. Cheng; M. T. Zuber; D. E. Smith

    1997-01-01

    In 1999 after a 3-year transit, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft will enter a low-altitude orbit around the asteroid, 433 Eros. Onboard the spacecraft, five facility instruments will operate continuously during the planned one-year orbit at Eros. One of these instruments, the NEAR Laser Rangefinder (NLR), will provide sufficiently high resolution and accurate topographical profiles that when combined with

  19. Cognitive Vision for Autonomous Satellite Rendezvous and Docking

    Microsoft Academic Search

    Faisal Qureshi; Demetri Terzopoulos; Piotr Jasiobedzki

    2005-01-01

    We present a cognitively-controlled vision system that com- bines low-level object recognition and tracking with high-level symbolic reasoning for the purpose of solving difficult space robotics problems—satellite rendezvous and docking. The rea- soning module, which encodes a model of the environment, performs deliberation to 1) guide the vision system in a task- directed manner, 2) activate vision modules depending on

  20. Relative navigation requirements for automatic rendezvous and capture systems

    NASA Technical Reports Server (NTRS)

    Kachmar, Peter M.; Polutchko, Robert J.; Chu, William; Montez, Moises

    1991-01-01

    This paper will discuss in detail the relative navigation system requirements and sensor trade-offs for Automatic Rendezvous and Capture. Rendezvous navigation filter development will be discussed in the context of navigation performance requirements for a 'Phase One' AR&C system capability. Navigation system architectures and the resulting relative navigation performance for both cooperative and uncooperative target vehicles will be assessed. Relative navigation performance using rendezvous radar, star tracker, radiometric, laser and GPS navigation sensors during appropriate phases of the trajectory will be presented. The effect of relative navigation performance on the Integrated AR&C system performance will be addressed. Linear covariance and deterministic simulation results will be used. Evaluation of relative navigation and IGN&C system performance for several representative relative approach profiles will be presented in order to demonstrate the full range of system capabilities. A summary of the sensor requirements and recommendations for AR&C system capabilities for several programs requiring AR&C will be presented.

  1. Supervised autonomous rendezvous and docking system technology evaluation

    NASA Astrophysics Data System (ADS)

    Marzwell, Neville I.

    Technology for manned space flight is mature and has an extensive history of the use of man-in-the-loop rendezvous and docking, but there is no history of automated rendezvous and docking. Sensors exist that can operate in the space environment. The Shuttle radar can be used for ranges down to 30 meters, Japan and France are developing laser rangers, and considerable work is going on in the U.S. However, there is a need to validate a flight qualified sensor for the range of 30 meters to contact. The number of targets and illumination patterns should be minimized to reduce operation constraints with one or more sensors integrated into a robust system for autonomous operation. To achieve system redundancy, it is worthwhile to follow a parallel development of qualifying and extending the range of the 0-12 meter MSFC sensor and to simultaneously qualify the 0-30(+) meter JPL laser ranging system as an additional sensor with overlapping capabilities. Such an approach offers a redundant sensor suite for autonomous rendezvous and docking. The development should include the optimization of integrated sensory systems, packaging, mission envelopes, and computer image processing to mimic brain perception and real-time response. The benefits of the Global Positioning System in providing real-time positioning data of high accuracy must be incorporated into the design. The use of GPS-derived attitude data should be investigated further and validated.

  2. Relative navigation requirements for automatic rendezvous and capture systems

    NASA Astrophysics Data System (ADS)

    Kachmar, Peter M.; Polutchko, Robert J.; Chu, William; Montez, Moises

    This paper will discuss in detail the relative navigation system requirements and sensor trade-offs for Automatic Rendezvous and Capture. Rendezvous navigation filter development will be discussed in the context of navigation performance requirements for a 'Phase One' AR&C system capability. Navigation system architectures and the resulting relative navigation performance for both cooperative and uncooperative target vehicles will be assessed. Relative navigation performance using rendezvous radar, star tracker, radiometric, laser and GPS navigation sensors during appropriate phases of the trajectory will be presented. The effect of relative navigation performance on the Integrated AR&C system performance will be addressed. Linear covariance and deterministic simulation results will be used. Evaluation of relative navigation and IGN&C system performance for several representative relative approach profiles will be presented in order to demonstrate the full range of system capabilities. A summary of the sensor requirements and recommendations for AR&C system capabilities for several programs requiring AR&C will be presented.

  3. Supervised autonomous rendezvous and docking system technology evaluation

    NASA Technical Reports Server (NTRS)

    Marzwell, Neville I.

    1991-01-01

    Technology for manned space flight is mature and has an extensive history of the use of man-in-the-loop rendezvous and docking, but there is no history of automated rendezvous and docking. Sensors exist that can operate in the space environment. The Shuttle radar can be used for ranges down to 30 meters, Japan and France are developing laser rangers, and considerable work is going on in the U.S. However, there is a need to validate a flight qualified sensor for the range of 30 meters to contact. The number of targets and illumination patterns should be minimized to reduce operation constraints with one or more sensors integrated into a robust system for autonomous operation. To achieve system redundancy, it is worthwhile to follow a parallel development of qualifying and extending the range of the 0-12 meter MSFC sensor and to simultaneously qualify the 0-30(+) meter JPL laser ranging system as an additional sensor with overlapping capabilities. Such an approach offers a redundant sensor suite for autonomous rendezvous and docking. The development should include the optimization of integrated sensory systems, packaging, mission envelopes, and computer image processing to mimic brain perception and real-time response. The benefits of the Global Positioning System in providing real-time positioning data of high accuracy must be incorporated into the design. The use of GPS-derived attitude data should be investigated further and validated.

  4. Fast solar sail rendezvous mission to near Earth asteroids

    NASA Astrophysics Data System (ADS)

    Zeng, Xiangyuan; Gong, Shengping; Li, Junfeng

    2014-12-01

    The concept of fast solar sail rendezvous missions to near Earth asteroids is presented by considering the hyperbolic launch excess velocity as a design parameter. After introducing an initial constraint on the hyperbolic excess velocity, a time optimal control framework is derived and solved by using an indirect method. The coplanar circular orbit rendezvous scenario is investigated first to evaluate the variational trend of the transfer time with respect to different hyperbolic excess velocities and solar sail characteristic accelerations. The influence of the asteroid orbital inclination and eccentricity on the transfer time is studied in a parametric way. The optimal direction and magnitude of the hyperbolic excess velocity are identified via numerical simulations. The found results for coplanar circular scenarios are compared in terms of fuel consumption to the corresponding bi-impulsive transfer of the same flight time, but without using a solar sail. The fuel consumption tradeoff between the required hyperbolic excess velocity and the achievable flight time is discussed. The required total launch mass for a particular solar sail is derived in analytical form. A practical mission application is proposed to rendezvous with the asteroid 99942 Apophis by using a solar sail in combination with the provided hyperbolic excess velocity.

  5. Trajectory Control of Rendezvous with Maneuver Target Spacecraft

    NASA Technical Reports Server (NTRS)

    Zhou, Zhinqiang

    2012-01-01

    In this paper, a nonlinear trajectory control algorithm of rendezvous with maneuvering target spacecraft is presented. The disturbance forces on the chaser and target spacecraft and the thrust forces on the chaser spacecraft are considered in the analysis. The control algorithm developed in this paper uses the relative distance and relative velocity between the target and chaser spacecraft as the inputs. A general formula of reference relative trajectory of the chaser spacecraft to the target spacecraft is developed and applied to four different proximity maneuvers, which are in-track circling, cross-track circling, in-track spiral rendezvous and cross-track spiral rendezvous. The closed-loop differential equations of the proximity relative motion with the control algorithm are derived. It is proven in the paper that the tracking errors between the commanded relative trajectory and the actual relative trajectory are bounded within a constant region determined by the control gains. The prediction of the tracking errors is obtained. Design examples are provided to show the implementation of the control algorithm. The simulation results show that the actual relative trajectory tracks the commanded relative trajectory tightly. The predicted tracking errors match those calculated in the simulation results. The control algorithm developed in this paper can also be applied to interception of maneuver target spacecraft and relative trajectory control of spacecraft formation flying.

  6. Squaring, Parity Breaking, and S Tumbling of Vesicles under Shear Flow

    NASA Astrophysics Data System (ADS)

    Farutin, Alexander; Misbah, Chaouqi

    2012-12-01

    The numerical study of 3D vesicles with a reduced volume equal to that of human red blood cells leads to the discovery of three types of dynamics: (i) squaring motion, in which the angle between the direction of the longest distance and the flow velocity undergoes discontinuous jumps over time, (ii) spontaneous parity breaking of the shape leading to cross-streamline migration, and (iii) S tumbling where the vesicle tumbles, exhibiting a pronounced S-like shape with a waisted morphology in the center. We report on the phase diagram within a wide range of relevant parameters. Our estimates reveal that healthy and pathological red blood cells are also prone to these types of motion, which may affect blood microcirculation and impact oxygen transport.

  7. Beef quality of different portions of the biceps femoris muscle in cattle improved by tumbling with brine.

    PubMed

    Silva, A A; Delgado, E F; Lobo, A R; Mourão, G B; Contreras-Castillo, C J

    2015-05-01

    The effect of tumbling with brines on different portions of the biceps femoris muscle was evaluated for the quality of beef from cattle older than 30 mo. Six biceps femoris muscles were divided into portions: origin (OP), insertion 1(IP1), and insertion 2 (IP2). The portions were sliced into steaks and were treated with no tumbling (control), tumbling with brine (BR), and tumbling with brine and hydrolyzed soy protein (BR+HSP). The steaks were vacuum packaged and stored for 1 and 12 d and then analyzed for pH, yield, color, cooking loss, and shear force. The control steaks from the OP had higher ( < 0.05) pH and shear force values and lower ( < 0.05) L* values than the control steaks from IP2. The pH and a* and b* values increased ( < 0.05) and the L* values and cooking loss decreased ( < 0.05) when the steaks were tumbled with BR and BR+HSP. Overall, substantial variation was found for the variables among the different portions of the biceps femoris muscle. Based on the lower lightness (low exudation) and greater yellow and red intensity (less oxidation) of the meat, the tumbling with brines improved the meat quality. However, the hydrolyzed soy protein incorporated into the brine did not increase the effect compared with using the brine alone for most of the variables. PMID:26020350

  8. Adaptive motion estimation of a tumbling satellite using laser-vision data with unknown noise characteristics

    Microsoft Academic Search

    Farhad Aghili; Kourosh Parsa

    2007-01-01

    A noise-adaptive variant of the Kalman filter is presented for the motion estimation and prediction of a free-falling tumbling satellite as seen from a satellite in a neighboring orbit. A complete dynamics model, including aspects of orbital mechanics, is incorporated for accurate estimation. Moreover, a discrete-time model of the entire system which includes the state-transition matrix and the covariance of

  9. Integrated GPS\\/INS navigation system design for autonomous spacecraft rendezvous

    Microsoft Academic Search

    David Edward Gaylor

    2003-01-01

    The goal of the NASA Space Launch Initiative (SLI) program is to advance the technologies for the next generation reusable launch vehicle (RLV). The SLI program has identified automated rendezvous and docking as an area requiring further research and development. Currently, the Space Shuttle uses a partially manual system for rendezvous, but a fully automated system could be safer and

  10. Multiple Agents RendezVous In a Ring in Spite of a Black Hole

    E-print Network

    Flocchini, Paola

    Multiple Agents RendezVous In a Ring in Spite of a Black Hole Stefan Dobrev1 , Paola Flocchini1 there is a black hole: a stationary process located at a node that destroys any incoming agent without leaving any trace. The presence of the black hole makes it clearly impossible for all agents to rendezvous. So

  11. Effects of Location-Aware Computing On Rendezvous David Dearman, Kirstie Hawkey, and Kori M. Inkpen

    E-print Network

    Hawkey, Kirstie

    Effects of Location-Aware Computing On Rendezvous Behaviour David Dearman, Kirstie Hawkey, and Kori, Canada, B3H 1W5 {dearman, hawkey, inkpen}@cs.dal.ca Abstract. This paper presents a field study. The results are then presented in a narrative form with discussion of the rendezvous #12;2 David Dearman

  12. The computation of optimal rendezvous trajectories using the sequential gradient-restoration algorithm

    Microsoft Academic Search

    2006-01-01

    In recent years, there has been a growing demand for the autonomous rendezvous and docking capability of a spacecraft. Current guidance methods in existence are based on the human control of the chaser spacecraft and are not suitable nor sufficient for an autonomous vehicle. The optimal solution of the rendezvous problem investigated in this thesis consists of finding an allowable

  13. Use of Framelets for Efficient Transmitter-Receiver Rendezvous in Wireless Sensor Networks

    E-print Network

    Roedig, Utz

    Use of Framelets for Efficient Transmitter-Receiver Rendezvous in Wireless Sensor Networks Andre transmitter and receiver. Since communication can only take place when the receiver's radio is active of framelets - small, fixed sized frames - to achieve transmitter-receiver rendezvous and contrasts

  14. A framework for Lyapunov certificates for multi-vehicle rendezvous problems

    Microsoft Academic Search

    Abhishek Tiwari; Jimmy Fung; John M. Carson III; Bhattacharya Richard; R. M. Murray

    2004-01-01

    In this paper, we present a dynamical systems representation for multi-agent rendezvous on the phase plane. We restrict our attention to two agents, each with scalar dynamics. The problem of rendezvous is cast as a stabilization problem, with a set of constraints on the trajectories of the agents, defined on the phase plane. We also describe a method to generate

  15. Importance of chain tumbling and finite extension on the start-up and relaxation behavior of transient networks

    NASA Astrophysics Data System (ADS)

    Sing, Michelle; Wang, Zhen-Gang; McKinley, Gareth; Olsen, Bradley

    2015-03-01

    Associative polymer networks are ubiquitous in tissue and biomedical engineering. However, the particular molecular attributes that contribute to the macroscopic behavior like shear thinning, self-healing, and yield stress are less well known. Here we incorporate chemical kinetics in the the Smoluchowski Equation capable of modeling the full network chain end-to-end distance distribution while tracking the fraction of looped, bridged, and dangling chains in the gel. In steady shear, we see the development of non-monotonic flow instabilities when the rate of chain association and dissociation are slower than the rate of chain relaxation. These instabilities arise due to a combination of chain finite extensibility and tumbling. During start-up of steady shear, the combination of these two phenomena also results in stress overshoots followed by multiple damped oscillations toward steady-state. The timescale of chain relaxation after the cessation of shear is dominated by the chain kinetics of association and dissociation as a function of the fraction of dangling chains present at any time post-shear. Institute for Soldier Nanotechnologies, Department of Defense National Defense Science and Engineering Fellowship Program.

  16. Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation

    NASA Technical Reports Server (NTRS)

    Miller, J. K.; Antreasian, P. J.; Georgini, J.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.

    1995-01-01

    Navigation of the orbit phase of the Near Earth steroid Rendezvous (NEAR) mission will re,quire determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was known about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light curve data provided a rough estimate of Eros shape and a fairly good estimate of the pole, prime meridian and spin rate. However, the determination of the NEAR spacecraft orbit requires a high precision model of Eros's physical parameters and the ground based data provides only marginal a priori information. Eros is the principal source of perturbations of the spacecraft's trajectory and the principal source of data for determining the orbit. The initial orbit determination strategy is therefore concerned with developing a precise model of Eros. The original plan for Eros orbital operations was to execute a series of rendezvous burns beginning on December 20,1998 and insert into a close Eros orbit in January 1999. As a result of an unplanned termination of the rendezvous burn on December 20, 1998, the NEAR spacecraft continued on its high velocity approach trajectory and passed within 3900 km of Eros on December 23, 1998. The planned rendezvous burn was delayed until January 3, 1999 which resulted in the spacecraft being placed on a trajectory that slowly returns to Eros with a subsequent delay of close Eros orbital operations until February 2001. The flyby of Eros provided a brief glimpse and allowed for a crude estimate of the pole, prime meridian and mass of Eros. More importantly for navigation, orbit determination software was executed in the landmark tracking mode to determine the spacecraft orbit and a preliminary shape and landmark data base has been obtained. The flyby also provided an opportunity to test orbit determination operational procedures that will be used in February of 2001. The initial attitude and spin rate of Eros, as well as estimates of reference landmark locations, are obtained from images of the asteroid. These initial estimates are used as a priori values for a more precise refinement of these parameters by the orbit determination software which combines optical measurements with Doppler tracking data to obtain solutions for the required parameters. As the spacecraft is maneuvered; closer to the asteroid, estimates of spacecraft state, asteroid attitude, solar pressure, landmark locations and Eros physical parameters including mass, moments of inertia and gravity harmonics are determined with increasing precision. The determination of the elements of the inertia tensor of the asteroid is critical to spacecraft orbit determination and prediction of the asteroid attitude. The moments of inertia about the principal axes are also of scientific interest since they provide some insight into the internal mass distribution. Determination of the principal axes moments of inertia will depend on observing free precession in the asteroid's attitude dynamics. Gravity harmonics are in themselves of interest to science. When compared with the asteroid shape, some insight may be obtained into Eros' internal structure. The location of the center of mass derived from the first degree harmonic coefficients give a direct indication of overall mass distribution. The second degree harmonic coefficients relate to the radial distribution of mass. Higher degree harmonics may be compared with surface features to gain additional insight into mass distribution. In this paper, estimates of Eros physical parameters obtained from the December 23,1998 flyby will be presented. This new knowledge will be applied to simplification of Eros orbital operations in February of 2001. The resulting revision to the orbit determination strategy will also be discussed.

  17. Rendezvous and proximity operations sensor candidates

    Microsoft Academic Search

    B. Kunkel; Ph. Hartl; W. Fehse

    1985-01-01

    As part of an ESA study, RVD and proximity operations on autonomous smart sensors for guidance between spacecraft are discussed. Measurement parameters for the sensors include range, range resolution, and range rate between 20 km and 0.1 m, and angular and lateral relative position between 20 km and 0.1 m. Sensors examined include a PRN Ku-band microwave range and attitude

  18. The effects of low salt concentrations on the mechanism of adhesion between two pieces of pork semimembranosus muscle following tumbling and cooking.

    PubMed

    Bombrun, Laure; Gatellier, Philippe; Carlier, Martine; Kondjoyan, Alain

    2014-01-01

    The aim of this research was to gain deeper insight into the effect of salt content on the adhesion between pieces of semimembranosus pork muscle bound by a tumbling exudate gel. Hydrophobic site number, free thiol and carbonyl content were measured in tumbling exudate and meat protein to evaluate the protein-protein interactions involved in the adhesion process. Proteins were far more oxidized in exudate than in meat, and under our experimental conditions, salt content increased protein bonding in the exudate but not in the meat. Breaking stress increased between non-salted meat and 0.8%-salted meat but did not depend on the protein physicochemical properties of the tumbling exudate. Modifying the meat surface by tumbling alone, tumbling and salting, or scarification had no effect on breaking stress. It is suggested that the break between the meat pieces occurred between the tumbling exudate and the meat surface due to weaker chemical bonds at this location. PMID:23896131

  19. Reference equations of motion for automatic rendezvous and capture

    NASA Technical Reports Server (NTRS)

    Henderson, David M.

    1992-01-01

    The analysis presented in this paper defines the reference coordinate frames, equations of motion, and control parameters necessary to model the relative motion and attitude of spacecraft in close proximity with another space system during the Automatic Rendezvous and Capture phase of an on-orbit operation. The relative docking port target position vector and the attitude control matrix are defined based upon an arbitrary spacecraft design. These translation and rotation control parameters could be used to drive the error signal input to the vehicle flight control system. Measurements for these control parameters would become the bases for an autopilot or feedback control system (FCS) design for a specific spacecraft.

  20. Longitudinal Trim and Tumble Characteristics of a 0.057-Scale Model of the Chance Vought XF7U-1 Airplane, TED NO. NACA DE311

    NASA Technical Reports Server (NTRS)

    Bryant, Robert L.

    1948-01-01

    Based on results of longitudinal trim and tumble tests of a 0.057-scale model of the Chance Vought XF7U-1 airplane, the following conclusions regarding the trim and tumble characteristics of the airplane have been drawn: 1. The airplane will not trim at any unusual or uncontrolled angles of attack. 2. The airplane will not tumble with the center of gravity located forward of 24 percent of the mean aerodynamic chord. When the center of gravity is located at 24 percent of the mean aerodynamic chord and slats are extended and elevators are deflected full up, the airplane may tumble if given an external positive pitching moment. 3. The tumbling motion obtained will be readily terminated by deflecting the elevators full down so as to oppose the rotation. 4. The accelerations encountered during an established tumble may be dangerous to the pilot and, therefore, action should be taken to terminate a tumble immediately upon its inception. 5. Simultaneous opening of two wing-tip parachutes having diameters of 4 feet or larger and having drag coefficients of approximately 0.7 will effectively terminate the tumble. 6. Model results indicate that the pilot will not be struck by the airplane if it becomes necessary to leave the airplane during a tumble. The pilot may require aid from an ejection-seat arrangement.

  1. Shuttle rendezvous radar performance evaluation and simulation

    NASA Astrophysics Data System (ADS)

    Griffin, John W.; Lindberg, Andrew C.; Ahn, Thomas B.; Harton, Paul L.

    The US Space Shuttle's Ku-band system was specifically designed for communications and tracking functions which are required during on-orbit operations with other spacecraft. Operating modes permit search and acquisition to be accomplished by computer designation or under manual control by the astronaut. Ku-band system data channels drive on-board dedicated displays and are incorporated into state vector updates by Shuttle guidance and navigation computers. Radar-cross-section estimates were used in computer simulations to predict the range at which radar detection and acquisition can be expected. Validity of the simulationi model and the radar design and performance were verified by flight tests on the White Sands test range. It is concluded that results of the testing established confidence in the capability of the system to provide the relative position and rate information which is needed for Shuttle work involving other spacecraft.

  2. Shuttle rendezvous radar performance evaluation and simulation

    NASA Technical Reports Server (NTRS)

    Griffin, John W.; Lindberg, Andrew C.; Ahn, Thomas B.; Harton, Paul L.

    1988-01-01

    The US Space Shuttle's Ku-band system was specifically designed for communications and tracking functions which are required during on-orbit operations with other spacecraft. Operating modes permit search and acquisition to be accomplished by computer designation or under manual control by the astronaut. Ku-band system data channels drive on-board dedicated displays and are incorporated into state vector updates by Shuttle guidance and navigation computers. Radar-cross-section estimates were used in computer simulations to predict the range at which radar detection and acquisition can be expected. Validity of the simulationi model and the radar design and performance were verified by flight tests on the White Sands test range. It is concluded that results of the testing established confidence in the capability of the system to provide the relative position and rate information which is needed for Shuttle work involving other spacecraft.

  3. Rough-and-Tumble Play and the Regulation of Aggression: An Observational Study of Father–Child Play Dyads

    PubMed Central

    Flanders, Joseph L.; Leo, Vanessa; Paquette, Daniel; Pihl, Robert O.; Séguin, Jean R.

    2012-01-01

    Rough-and-tumble play (RTP) is a common form of play between fathers and children. It has been suggested that RTP can contribute to the development of selfregulation. This study addressed the hypothesis that the frequency of father–child RTP is related to the frequency of physically aggressive behavior in early childhood. This relationship was expected to be moderated by the dominance relationship between father and son during play. Eighty-five children between the ages of 2 and 6 years were videotaped during a free-play session with their fathers in their homes and questionnaire data was collected about father–child RTP frequency during the past year. The play dyads were rated for the degree to which the father dominated play interactions. A significant statistical interaction revealed that RTP frequency was associated with higher levels of physical aggression in children whose fathers were less dominant. These results indicate that RTP is indeed related to physical aggression, though this relationship is moderated by the degree to which the father is a dominant playmate. PMID:19431190

  4. Autonomous control procedures for shuttle rendezvous proximity operations

    NASA Technical Reports Server (NTRS)

    Lea, Robert N.; Mitchell, Eric V.; Goodwin, Mary Ann

    1987-01-01

    The results are presented of a study which uses fuzzy sets to model a Space Shuttle pilot's reasoning and actions while performing rendezvous proximity operation maneuvers. In this model fuzzy sets are used to simulate smooth and continuous actions as would be expected from an experienced pilot and to simulate common sense reasoning in the decision process. The present model assumes visual information available to the Shuttle pilot from the Shuttle Crew Optical Alignment Sighting (COAS) device and the overhead window and rendezvous radar sensor information available to him from an onboard display. This model will be used in a flight analysis simulator to perform studies requiring a large number of runs, each of which currently needs an engineer in the loop to supply the piloting decisions. This work has much broader implications in control of robots such as the Flight Telerobotic Servicer, in automated pilot control and attitude control, and in advisory and evaluation functions that could be used for flight data monitoring or for testing of various rule sets in flight preparation.

  5. An autonomous rendezvous and docking system using cruise missile technologies

    NASA Technical Reports Server (NTRS)

    Jones, Ruel Edwin

    1991-01-01

    In November 1990 the Autonomous Rendezvous & Docking (AR&D) system was first demonstrated for members of NASA's Strategic Avionics Technology Working Group. This simulation utilized prototype hardware from the Cruise Missile and Advanced Centaur Avionics systems. The object was to show that all the accuracy, reliability and operational requirements established for a space craft to dock with Space Station Freedom could be met by the proposed system. The rapid prototyping capabilities of the Advanced Avionics Systems Development Laboratory were used to evaluate the proposed system in a real time, hardware in the loop simulation of the rendezvous and docking reference mission. The simulation permits manual, supervised automatic and fully autonomous operations to be evaluated. It is also being upgraded to be able to test an Autonomous Approach and Landing (AA&L) system. The AA&L and AR&D systems are very similar. Both use inertial guidance and control systems supplemented by GPS. Both use an Image Processing System (IPS), for target recognition and tracking. The IPS includes a general purpose multiprocessor computer and a selected suite of sensors that will provide the required relative position and orientation data. Graphic displays can also be generated by the computer, providing the astronaut / operator with real-time guidance and navigation data with enhanced video or sensor imagery.

  6. Compressing an Elliptic Vortex: Transition to Turbulence by Tumble Breakdown

    NASA Technical Reports Server (NTRS)

    Godeferd, Fabien S.; Mansour, Nagi N.; Cambon, Claude

    1996-01-01

    Stability of the elliptic vortex attracted interest in the past decade. Cambon (1982), and Cambon, Teissedre and Jeandel (1985) have studied the stability of such flows with spatially uniform velocity gradient, and have provided RDT solutions for a wide range of the parameter S/Omega (where the strain rate S and the vorticity 2 Omega define the velocity gradient matrix). The range studied included those of hyperbolic streamlines (strain dominated, S/Omega is greater than 1), linear streamlines (simple shear, S/Omega = 1), and elliptical streamlines (vorticity dominated, S/Omega is less than 1). The latter class has more recently attracted interest and several studies appeared (Pierrehumbert 1986, Bayly 1986, Craik and Criminale 1986). These studies will be collectively referred to as PBCC.

  7. Gossip-Based Solutions for Discrete Rendezvous in Populations of Communicating Agents

    PubMed Central

    Hollander, Christopher D.; Wu, Annie S.

    2014-01-01

    The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm. PMID:25397882

  8. A Time and Place for Everything: A Discrete Systems Perspective on the Role of Children's Rough-and-Tumble Play in Educational Settings.

    ERIC Educational Resources Information Center

    MacDonald, Kevin

    1992-01-01

    Notes that rough-and-tumble play must be considered in the context of social values; has beneficial influences on children's cognitive and social development; and is distinguishable from aggression. Makes a case for the use of socializing techniques in conjunction with rough and tumble play. (LB)

  9. Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense

    E-print Network

    Aures-Cavalieri, Kurt D

    2014-12-04

    including spacecraft rendezvous and missile interception. Behavior learning techniques can be used to estimate the strategy of an opponent and augment the pursuit-evasion game into a one-sided optimal control problem. The application of behavior learning...

  10. IFAC W. C. 2005, To appear ON ROBUST RENDEZVOUS FOR MOBILE

    E-print Network

    Bullo, Francesco

    IFAC W. C. 2005, To appear ON ROBUST RENDEZVOUS FOR MOBILE AUTONOMOUS AGENTS Sonia Mart´inez Jorge topologies for our algorithms via the notion of "proxim- ity graph," see (Jaromczyk and Toussaint, 1992

  11. An application of linear covariance analysis to the design of responsive near-rendezvous missions

    E-print Network

    Visser, Benjamin Lee

    2007-01-01

    This thesis investigates a new class of launch vehicles capable of being released from an aircraft which ultimately have the goal of achieving near-rendezvous conditions at orbital altitudes up to 800 km. These launch ...

  12. Avionics and control system development for mid-air rendezvous of two unmanned aerial vehicles

    E-print Network

    Park, Sanghyuk, 1973-

    2004-01-01

    A flight control system was developed to achieve mid-air rendezvous of two unmanned aerial vehicles (UAVs) as a part of the Parent Child Unmanned Aerial Vehicle (PCUAV) project at MIT and the Draper Laboratory. A lateral ...

  13. A vision based control system for autonomous rendezvous and capture of a Mars Orbital Sample

    E-print Network

    Jyothindran, Vishnu

    2013-01-01

    NASA's Mars Sample Return (MSR) mission involves many challenging operations. The current mission scenario utilizes a small Orbiting Sample (OS) satellite, launched from the surface of Mars, which will rendezvous with an ...

  14. Methodology for prototyping increased levels of automation for spacecraft rendezvous functions

    E-print Network

    Hart, Jeremy Jay

    2009-05-15

    The Crew Exploration Vehicle (CEV) necessitates higher levels of automation than previous NASA vehicles due to program requirements for automation, including Automated Rendezvous and Docking (AR&D). Studies of spacecraft development often point...

  15. STS 63 Flight Day 4 Highlights/MIR-Shuttle Rendezvous

    NASA Technical Reports Server (NTRS)

    1995-01-01

    STS 63 Flight, day 4, the MIR-Shuttle rendezvous is highlighted in this video. The six-member team in the Shuttle are introduced and discuss their functions and tests for this day of the flight. There is actual footage of earth from space, of the MIR Space Station, a tour of the Shuttle cockpit, some footage from the MIR of the Space Shuttle, and footage from inside the MIR with the cosmonauts. Mission control communications with the Shuttle, communication between the Shuttle and MIR, and an historic communication between the Shuttle's astronauts and President Bill Clinton are included. President Clinton interviews each of the six-member team and discusses the upcoming space walk by Dr. Bernard Harris, the first black astronaut to walk in space. This video was recorded on February 6, 1995.

  16. STS 63 flight day 4 highlights/MIR-Shuttle rendezvous

    NASA Astrophysics Data System (ADS)

    1995-02-01

    STS 63 Flight, day 4, the MIR-Shuttle rendezvous is highlighted in this video. The six-member team in the Shuttle are introduced and discuss their functions and tests for this day of the flight. There is actual footage of earth from space, of the MIR Space Station, a tour of the Shuttle cockpit, some footage from the MIR of the Space Shuttle, and footage from inside the MIR with the cosmonauts. Mission control communications with the Shuttle, communication between the Shuttle and MIR, and an historic communication between the Shuttle's astronauts and President Bill Clinton are included. President Clinton interviews each of the six-member team and discusses the upcoming space walk by Dr. Bernard Harris, the first black astronaut to walk in space. This video was recorded on February 6, 1995.

  17. Stereo-based tracking system for automated rendezvous and capture

    NASA Astrophysics Data System (ADS)

    Smith, Alan T.; Fisher, Timothy E.

    1993-09-01

    In the past, NASA tracking systems which provided range and bearing to targets have primarily been radar based. Advanced projects such as unmanned missions to the moon and Mars need automated rendezvous and capture (AR&C) to reduce operating costs and improve mission reliability. In the Tracking Techniques Branch at Johnson Space Center we are investigating the feasibility of a stereo digital image based sensor for AR&C. This system differs from traditional stereo systems in two significant ways. First, a passive cooperative target is used to calculate the range to three specific points as opposed to calculating a range map of the entire scene. The second unique feature is the image processing algorithms that are used to identify the target. In this paper the sensor's performance is compared to preliminary AR&C operating range and accuracy requirements. A theoretical error model is presented that predicts the sensor's accuracy as a function of range.

  18. Study of a comet rendezvous mission, volume 1

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The feasibility, scientific objectives, modes of exploration and implementation alternatives of a rendezvous mission to Encke's comet in 1984 are considered. Principal emphasis is placed on developing the scientific rationale for such a mission, based on available knowledge and best estimates of this comet's physical characteristics, including current theories of its origin, evolution and composition. Studied are mission profile alternatives, performance tradeoffs, preferred exploration strategy, and a spacecraft design concept capable of performing this mission. The study showed that the major scientific objectives can be met by a Titan IIID/Centaur-launched 17.5 kw solar electric propulsion spacecraft which carries 60 kg of scientific instruments and is capable of extensive maneuvering within the comet envelope to explore the coma, tail and nucleus.

  19. Halo: Managing Node Rendezvous in Opportunistic Sensor Networks

    NASA Astrophysics Data System (ADS)

    Eisenman, Shane B.; Lu, Hong; Campbell, Andrew T.

    One vision of an opportunistic sensor network (OSN) uses sensor access points (SAPs) to assign mobile sensors with sensing tasks submitted by applications that could be running anywhere. Tasked mobile sensors might upload sensed data back to these applications via subsequent encounters with this SAP tier. In a people-centric OSN, node mobility is uncontrolled and the architecture relies on opportunistic rendezvous between human-carried sensors and SAPs to provide tasking/uploading opportunities. However, in many reasonable scenarios application queries have a degree of time sensitivity such that the sensing target must be sampled and/or the resulting sensed data must be uploaded within a certain time window to be of greatest value. Halo efficiently, in terms of packet overhead and mobile sensor energy, provides improved delay performance in OSNs by: (i) managing tasking/uploading opportunity, and (ii) using mobility-informed scheduling at the SAP.

  20. New developments in astrodynamics algorithms for autonomous rendezvous

    NASA Technical Reports Server (NTRS)

    Klumpp, Allan R.

    1991-01-01

    A the core of any autonomous rendezvous guidance system must be two algorithms for solving Lambert's and Kepler's problems, the two fundamental problems in classical astrodynamics. Lambert's problem is to determine the trajectory connecting specified initial and terminal position vectors in a specified transfer time. The solution is the initial and terminal velocity vectors. Kepler's problem is to determine the trajectory that stems from a given initial state (position and velocity). The solution is the state of an earlier or later specified time. To be suitable for flight software, astrodynamics algorithms must be totally reliable, compact, and fast. Although solving Lambert's and Kepler's problems has challenged some of the world's finest minds for over two centuries, only in the last year have algorithms appeared that satisfy all three requirements just stated. This paper presents an evaluation of the most highly regarded Lambert and Kepler algorithms.

  1. Rendezvous Integration Complexities of NASA Human Flight Vehicles

    NASA Technical Reports Server (NTRS)

    Brazzel, Jack P.; Goodman, John L.

    2009-01-01

    Propellant-optimal trajectories, relative sensors and navigation, and docking/capture mechanisms are rendezvous disciplines that receive much attention in the technical literature. However, other areas must be considered. These include absolute navigation, maneuver targeting, attitude control, power generation, software development and verification, redundancy management, thermal control, avionics integration, robotics, communications, lighting, human factors, crew timeline, procedure development, orbital debris risk mitigation, structures, plume impingement, logistics, and in some cases extravehicular activity. While current and future spaceflight programs will introduce new technologies and operations concepts, the complexity of integrating multiple systems on multiple spacecraft will remain. The systems integration task may become more difficult as increasingly complex software is used to meet current and future automation, autonomy, and robotic operation requirements.

  2. SIMONE: A fleet of Near-Earth Object rendezvous microsatellites

    NASA Astrophysics Data System (ADS)

    Green, S. F.; Wells, N. S.; Ball, A. J.; Bernelli-Zazzera, F.; Perozzi, E.; Townend, M.; Walker, R. G.; Zarnecki, J. C.

    2003-04-01

    The SIMONE (Spacecraft Intercept Missions to Objects Near Earth) concept has recently been developed as part of an ESA-funded study (Near Earth Objects Space Mission Preparation). The SIMONE study, led by QinetiQ, with scientific aspects led by the Open University's Planetary and Space Sciences Research Institute, is to help understand the diversity of the NEO population using a fleet of microsatellite-class (~120 kg) interplanetary spacecraft with solar electric propulsion. The low cost approach (<50 MEuro for the first and 30 MEuro for subsequent spacecraft) allows a fleet of spacecraft to be deployed for the budget of a typical interplanetary mission. Each spacecraft will rendezvous with a different Near-Earth Object to perform key physical, morphological and compositional measurements relevant to NEO risk assessment as well as scientific investigation. We present the main features of the spacecraft design, measurement objectives, payload, target NEOs and mission operations.

  3. Single photon lidar demonstrator for asteroid rendezvous missions

    NASA Astrophysics Data System (ADS)

    Vacek, Michael; Michalek, Vojtech; Peca, Marek; Prochazka, Ivan; Blazej, Josef; Djurovic, Goran

    2015-01-01

    We present compact single photon lidar demonstrator dedicated for asteroid rendezvous missions. The instrument provides crucial data on altitude and terrain profile for altitudes exceeding 5km with a precision of less than 10 cm fulfilling the Rayleigh criterion. Transmitter and receiver optics designs are discussed, control and processing electronics based on a single rad-hard compatible FPGA (Field Programmable Gate Array) is analyzed. The FPGA electronics subsystems are TDC (Time-to-Digit Converter), laser trigger pulse generator and gate generator. Indoor calibration procedures of the whole demonstrator chain are proposed and evaluated. The calibration covers positioning of receiver and transmitter optics related to detector and laser, aligning of transmitter and receiver optical common paths. The retrieving strategy of terrain elevation profile is proposed and via indoor tests validated. Theory for surface slope and scanning is established, simulation and measurement results are compared and discussed.

  4. A stochastic model for bacterial dynamics toward point food sources with emergent run-and-tumble

    NASA Astrophysics Data System (ADS)

    Jashnsaz, Hossein; Nguyen, Tyler; Petrache, Horia; Presse, Steve; StatPhysBio Team

    2015-03-01

    Despite stark differences in chemotactic signaling networks and flagellar physiology across bacterial species, all bacteria sense their environment through a series of stochastic detection events (``hits'') at their chemoreceptors and bias their random walk on the basis of this information. We present a general statistical model describing how bacteria locate point sources of food on the basis of stochastic event detection, rather than gradient information. We show how model parameters can be directly inferred using maximum likelihood methods from microscopy tracking data. We find that ``run-and-tumble'' dynamics naturally emerge from our statistical model and recapitulate known results from experiments when we consider bacterial dynamics in well-controlled chemoattractant gradients. However, our model goes beyond reproducing known run-and-tumble statistics. It also makes a number of predictions unique to bacteria tracking point sources. In our model, all parameters are directly inferred from tracking data thus there are no adjustable parameters; detection events by bacteria are assumed stochastic as they occur in nature; and our ``top-down'' modeling approach is broadly applicable across bacterial species. SP acknowledges the NSF (MCB-1412259), the Purdue Research Foundation and his IUPUI Start-up.

  5. The comet rendezvous asteroid flyby mission: A status report

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Neugebauer, Marcia

    1991-01-01

    The Comet Rendezvous Asteroid Flyby (CRAF) mission received a new start in fiscal year 1990. CRAF will match orbits with an active short-period comet and follow it around the Sun, making scientific measurements of the nucleus, coma, and tail. The Imaging system will map the nucleus surface at a resolution of 1 meter/line-pair or better, while Visible and Infrared Mapping Spectrometer (VIMS) and Thermal Infrared Radiometer Experiment (TIREX) will produce spectral and thermal maps of the surface. Onboard instruments will collect cometary dust, ice, and gases and perform elemental and molecular analysis. A suite of fields and particles instruments will observe the solar wind interaction with the cometary atmosphere and tail. Radio tracking of the spacecraft will provide an accurate measure of the nucleus mass and higher harmonics in the comet's gravity field. En route to the comet, the spacecraft will make a close flyby of a large asteroid, preferably a primitive type from the outer main belt. Observations at the asteroid include remote sensing mapping of the surface, detection of any solar wind interaction observable at the flyby distance, and measurement of the asteroid mass to better than 10 percent accuracy. Detailed design of the CRAF spacecraft is currently underway at the Jet Propulsion Laboratory (JPL). Recent mass growth has necessitated a switch to Venus-Earth gravity assist type trajectories, similar to that used by the Galileo spacecraft. These trajectories require longer flight times from launch to rendezvous with the target comet. The details of the current baseline mission, spacecraft design, and instrument payload will be reviewed.

  6. Deep Interior: Multiple-Rendezvous Prospecting of NEOs

    NASA Astrophysics Data System (ADS)

    Kakuda, R. Y.; Asphaug, E.; Belton, M. J. S.; Gulkis, S.; Huebner, W. F.

    2000-10-01

    This is an international multiple-rendezvous mission designed to prospect the deep interior and subsurface geophysical properties of diverse near-Earth objects, using reflection radar tomography, imaging, gravity, and explosions. What we learn will greatly influence future missions and guide strategies for the diversion, disruption, or utilization of potentially hazardous objects. Deep Interior. Low-frequency radar to determine internal variations of complex permittivity at resolutions approaching 20 m. Map inclusions or voids, fracture geometries, and compositional or structural boundaries. Subsurface. High-frequency radar to determine depth of regolith, existence and nature of cometary mantle, geology beneath and around craters, and subsurface expressions to surface geology. Topography and Geodesy. Stereogrammetric imaging with 1 m/pixel spatial resolution, supplemented by radar altimetry in shadowed regions, to determine detailed shape, volume, and spin state. Compare with radar sounding to learn how internal structure is manifested on the surface. Mass and Density. Total mass and lower moments of the internal mass distribution by mapping the exterior gravitational field. Look for mass concentrations. Surface microphysics and composition. Map color, albedo, and scattering properties of the surface over sunlit regions in six optical filters. Material properties. Deploy grenades to characterize the mechanics and dynamics of surface materials. Record 8 frame/sec, 20 cm/pixel videos of crater formation and ejecta dynamics, to enable simple and direct laboratory constraints on material density, cohesion and porosity. Dust. Look for dust lofted by surface waves propagating from the explosions, to constrain elastic properties and attenuation. Observe longer-term dynamics and optical properties of dust "atmosphere" generated by human activity. Cometary Activity. At comet 107P/Wilson-Harrington, look for expressions of past cometary activity, and for possible awakening from dormancy by explosions. NEO Diversity. Assess the diversity of the interior structures in two classes of near-Earth objects. New Technology. SEP, first multiple rendezvous, autonav, first grenades. Precursor to geoseismic investigations.

  7. A feasibility study of unmanned rendezvous and docking in Mars orbit: Midterm review

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The ascent, rendezvous, docking and sample transfer operations in a potential MSSR mission that uses the Mars orbital rendezvous mode are considered. In order that the design choices made for these operations remain compatible with the rest of the mission, the impact on the Earth launch, Mars landing and orbiting and Earth return phase are also being assessed. The selection and description of a preliminary baseline concept are presented.

  8. The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration

    Microsoft Academic Search

    Fred D. Roe; Richard T. Howard

    2003-01-01

    During the 1990's, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture\\/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video

  9. The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration

    Microsoft Academic Search

    Fred D. Roe; Richard T. Howard

    2003-01-01

    During the 1990’s, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture\\/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video

  10. Dynamics of DNA tumbling in shear to rotational mixed flows: Pathways and periods Joo Sung Lee,1

    E-print Network

    Shaqfeh, Eric

    ,7 . Considering planar mixed flows, the dimensionless velocity gradient is given by ui xj = 0 1 0 0 0 0 0 0 , 1 with respect to the coil-stretch transi- tion 8 , Shaqfeh, Chu, and co-workers have investigated DNA tumbling microflu- idic geometries, including grooved or curved channels and cavity flows, have been designed

  11. Canadian Female and Male Early Childhood Educators' Perceptions of Child Aggression and Rough-and-Tumble Play

    ERIC Educational Resources Information Center

    Bosacki, Sandra; Woods, Heather; Coplan, Robert

    2015-01-01

    This study investigated female and male early childhood educators' (ECEs) perceptions of young children's aggression and rough-and-tumble play in the Canadian early childhood classroom. Participants were drawn from a larger sample of ECEs who completed an online questionnaire regarding their perceptions of young children's behaviours in the…

  12. Comparative study of in-cylinder tumble flows in an internal combustion engine using different piston shapes—an insight using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Murali Krishna, B.; Mallikarjuna, J. M.

    2010-05-01

    This paper deals with the experimental investigations of the in-cylinder tumble flows in a single-cylinder engine with five different piston crown shapes at an engine speed of 1,000 rev/min., during suction and compression strokes under motoring conditions using particle image velocimetry. Two-dimensional in-cylinder tumble flow measurements and analysis are carried out in combustion space on a vertical plane passing through cylinder axis. Ensemble average velocity vectors are used to analyze the tumble flow structure. Tumble ratio and average turbulent kinetic energy are evaluated and used to characterize the tumble flows. From results, it is found that at end of compression, pentroof-offset-bowl piston shows about 41 and 103% improvement in tumble ratio and average turbulent kinetic energy respectively, compared to that of flat piston. The present study will be useful in understanding effect of piston crown shapes on nature of the in-cylinder fluid tumble flows under real engine conditions.

  13. Tumbling/squish interaction in loop-scavenged two-stroke engines

    SciTech Connect

    Tsui, Y.Y.; Cheng, H.P. [National Chiao Tung Univ., Hsinchu (Taiwan, Province of China). Dept. of Mechanical Engineering

    1997-12-01

    This article describes a numerical investigation of the flow in a loop-scavenged two-stroke engine equipped with a head-bowl combustion chamber. The bowl is either placed in the center of the cylinder head or displaced away from the center. Attention is focused on the period of compression and early expansion. Results show that the effects of compression of the tumbling vortex by the piston become prominent after the midcompression stage, resulting in significant cascading of energy from mean flow to turbulence, followed by a fast decay of turbulence. The subsequent emergence of squish and reverse squish helps retard the decay. As a consequence, the cases with head bowls possess higher levels of mean flow and turbulence than those without bowls at top dead center and the later stage. It is also shown in the results that the offset of the head bowl had significant effects on the mean flow and turbulence characteristics, highly dependent on the offset direction.

  14. Autonomous Mission Manager for Rendezvous, Inspection and Mating

    NASA Technical Reports Server (NTRS)

    Zimpfer, Douglas J.

    2003-01-01

    To meet cost and safety objectives, space missions that involve proximity operations between two vehicles require a high level of autonomy to successfully complete their missions. The need for autonomy is primarily driven by the need to conduct complex operations outside of communication windows, and the communication time delays inherent in space missions. Autonomy also supports the goals of both NASA and the DOD to make space operations more routine, and lower operational costs by reducing the requirement for ground personnel. NASA and the DoD have several programs underway that require a much higher level of autonomy for space vehicles. NASA's Space Launch Initiative (SLI) program has ambitious goals of reducing costs by a factor or 10 and improving safety by a factor of 100. DARPA has recently begun its Orbital Express to demonstrate key technologies to make satellite servicing routine. The Air Force's XSS-ll program is developing a protoflight demonstration of an autonomous satellite inspector. A common element in space operations for many NASA and DOD missions is the ability to rendezvous, inspect anclJor dock with another spacecraft. For DARPA, this is required to service or refuel military satellites. For the Air Force, this is required to inspect un-cooperative resident space objects. For NASA, this is needed to meet the primary SLI design reference mission of International Space Station re-supply. A common aspect for each of these programs is an Autonomous Mission Manager that provides highly autonomous planning, execution and monitoring of the rendezvous, inspection and docking operations. This paper provides an overview of the Autonomous Mission Manager (AMM) design being incorporated into many of these technology programs. This AMM provides a highly scalable level of autonomous operations, ranging from automatic execution of ground-derived plans to highly autonomous onboard planning to meet ground developed mission goals. The AMM provides the capability to automatically execute the plans and monitor the system performance. In the event of system dispersions or failures the AMM can modify plans or abort to assure overall system safety. This paper describes the design and functionality of Draper's AMM framework, presents concept of operations associated with the use of the AMM, and outlines the relevant features of the flight demonstrations.

  15. NEP for a Kuiper Belt Object Rendezvous Mission

    SciTech Connect

    HOUTS,MICHAEL G.; LENARD,ROGER X.; LIPINSKI,RONALD J.; PATTON,BRUCE; POSTON,DAVID I.; WRIGHT,STEVEN A.

    1999-11-03

    Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOS with a diameter greater than 100 km. KBOS are postulated to be composed of the pristine material which formed our solar system and may even have organic materials in them. A detailed study of KBO size, orbit distribution, structure, and surface composition could shed light on the origins of the solar system and perhaps even on the origin of life in our solar system. A rendezvous mission including a lander would be needed to perform chemical analysis of the surface and sub-surface composition of KBOS. These requirements set the size of the science probe at around a ton. Mission analyses show that a fission-powered system with an electric thruster could rendezvous at 40 AU in about 13.0 years with a total {Delta}V of 46 krnk. It would deliver a 1000-kg science payload while providing ample onboard power for relaying data back to earth. The launch mass of the entire system (power, thrusters, propellant, navigation, communication, structure, science payload, etc.) would be 7984 kg if it were placed into an earth-escape trajectory (C=O). Alternatively, the system could be placed into a 700-km earth orbit with more propellant,yielding a total mass in LEO of 8618 kg, and then spiral out of earth orbit to arrive at the KBO in 14.3 years. To achieve this performance, a fission power system with 100 kW of electrical power and a total mass (reactor, shield, conversion, and radiator) of about 2350 kg. Three possible configurations are proposed: (1) a UZrH-fueled, NaK-cooled reactor with a steam Rankine conversion system, (2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heatpipe-cooled reactor with a recuperated Brayton conversion system. (Boiling and condensation in the Rankine system is a technical risk at present.) All three of these systems have the potential to meet the weight requirement for the trip and to be built in the near term.

  16. NEP for a Kuiper Belt Object rendezvous mission

    NASA Astrophysics Data System (ADS)

    Lipinski, Ronald J.; Lenard, Roger X.; Wright, Steven A.; Houts, Michael G.; Patton, Bruce; Poston, David I.

    2000-01-01

    Kuiper Belt Objects (KBOs) are a recently-discovered set of solar system bodies which lie at about the orbit of Pluto (40 AU) out to about 100 astronomical units (AU). There are estimated to be about 100,000 KBOs with a diameter greater than 100 km. KBOs are postulated to be composed of the pristine material which formed our solar system and may even have organic materials in them. A detailed study of KBO size, orbit distribution, structure, and surface composition could shed light on the origins of the solar system and perhaps even on the origin of life in our solar system. A rendezvous mission including a lander would be needed to perform chemical analysis of the surface and sub-surface composition of KBOs. These requirements set the size of the science probe at around a ton. Mission analyses show that a fission-powered system with an electric thruster could rendezvous at 40 AU in about 13.0 years with a total DV of 46 km/s. It would deliver a 1000-kg science payload while providing ample onboard power for relaying data back to earth. The launch mass of the entire system (power, thrusters, propellant, navigation, communication, structure, science payload, etc.) would be 7984 kg if it were placed into an earth-escape trajectory (C=0). Alternatively, the system could be placed into a 700-km earth orbit with more propellant, yielding a total mass in LEO of 8618 kg, and then spiral out of earth orbit to arrive at the KBO in 14.3 years. To achieve this performance, a fission power system with 100 kW of electrical power and a total mass (reactor, shield, conversion, and radiator) of about 2350 kg. Three possible configurations are proposed: (1) a UZrH-fueled, NaK-cooled reactor with a steam Rankine conversion system, (2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heatpipe-cooled reactor with a recuperated Brayton conversion system. (Boiling and condensation in the Rankine system is a technical risk at present.) All three of these systems have the potential to meet the weight requirement for the trip and to be built in the near term. .

  17. Space shuttle Ku-band integrated rendezvous radar/communications system study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The results are presented of work performed on the Space Shuttle Ku-Band Integrated Rendezvous Radar/Communications System Study. The recommendations and conclusions are included as well as the details explaining the results. The requirements upon which the study was based are presented along with the predicted performance of the recommended system configuration. In addition, shuttle orbiter vehicle constraints (e.g., size, weight, power, stowage space) are discussed. The tradeoffs considered and the operation of the recommended configuration are described for an optimized, integrated Ku-band radar/communications system. Basic system tradeoffs, communication design, radar design, antenna tradeoffs, antenna gimbal and drive design, antenna servo design, and deployed assembly packaging design are discussed. The communications and radar performance analyses necessary to support the system design effort are presented. Detailed derivations of the communications thermal noise error, the radar range, range rate, and angle tracking errors, and the communications transmitter distortion parameter effect on crosstalk between the unbalanced quadriphase signals are included.

  18. Electron Spin-Lattice Relaxation Mechanisms of Rapidly-Tumbling Nitroxide Radicals

    PubMed Central

    Biller, Joshua R.; Elajaili, Hanan; Meyer, Virginia; Rosen, Gerald M.; Eaton, Sandra S.; Eaton, Gareth R.

    2013-01-01

    Electron spin relaxation times at 295 K were measured at frequencies between 250 MHz and 34 GHz for perdeuterated 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (PDT) in five solvents with viscosities that result in tumbling correlation times, ?R, between 4 and 50 ps and for three 14N/15N pairs of nitroxides in water with ?R between 9 and 19 ps. To test the impact of structure on relaxation three additional nitroxides with ?R between 10 and 26 ps were studied. In this fast tumbling regime T2?1 ? T1?1 at frequencies up to about 9 GHz. At 34 GHz T2?1 > T1?1 due to increased contributions to T2?1 from incomplete motional averaging of g-anisotropy, and T2?1 ? T1?1 is proportional to ?R. The contribution to T1?1 from spin rotation is independent of frequency and decreases as ?R increases. Spin rotation dominates T1?1 at 34 GHz for all ?R studied, and at all frequencies studied for ?R = 4 ps. The contribution to T1?1 from modulation of nitrogen hyperfine anisotropy increases as frequency decreases and as ?R increases; it dominates at low frequencies for ?R > ? 15 ps. The contribution from modulation of g anisotropy is significant only at 34 GHz. Inclusion of a thermally-activated process was required to account for the observation that for most of the radicals, T1?1 was smaller at 250 MHz than at 1 to 2 GHz. The significant 15N/14N isotope effect, the small H/D isotope effect, and the viscosity dependence of the magnitude of the contribution from the thermally-activated process suggest that it arises from intramolecular motions of the nitroxide ring that modulate the isotropic A values. PMID:24056272

  19. Active sensor system for automatic rendezvous and docking

    NASA Astrophysics Data System (ADS)

    Howard, Richard T.; Bryan, Thomas C.; Book, Michael L.; Jackson, John L.

    1997-08-01

    NASA's Marshall Space Flight Center has developed an active sensor system, the ideo guidance sensor (VGS), to provide near-range relative position and attitude data. The VGS will be part of an automatic rendezvous and docking system. The VGS determines the relative positions and attitudes between the active sensor and the passive target. It works by using laser diodes to illuminate the retro-reflectors in the target, a solid-state camera to detect the return from the target retro-reflectors, and a frame grabber and digital signal processor to convert the video information into relative positions and attitudes. The current sensor design is the result of several years of development and testing, and it is being built to fly as an experiment payload on the space shuttle. The VGS system is designed to operate with the target completely visible within a relative azimuth of +/- 10.5 degrees and a relative elevation of +/- 8 degrees. The system will acquire and track and target within that field-of-view anywhere from 1.0 meters to 110 meters range at any relative roll angle and relative pitch and yaw attitudes of up to +/- 10 degrees. The data is output from the sensor at 5 Hz, and the target and sensor software have been designed to permit two independent sensors to operate simultaneously for redundancy.

  20. Ku-Band rendezvous radar performance computer simulation model

    NASA Technical Reports Server (NTRS)

    Magnusson, H. G.; Goff, M. F.

    1984-01-01

    All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total software package developed on this program; and (3) development of radar cross section (RCS) computation models for three additional satellites. All changes in the tracking model involved improvements in the automatic gain control (AGC) and the radar signal strength (RSS) computer models. Although the search and acquisition computer models were developed under the auspices of the Hughes Aircraft Company Ku-Band Integrated Radar and Communications Subsystem program office, they have been supplied to NASA as part of the Ku-band radar performance comuter model package. Their purpose is to predict Ku-band acquisition performance for specific satellite targets on specific missions. The RCS models were developed for three satellites: the Long Duration Exposure Facility (LDEF) spacecraft, the Solar Maximum Mission (SMM) spacecraft, and the Space Telescopes.

  1. Hubble Servicing Challenges Drive Innovation of Shuttle Rendezvous Techniques

    NASA Technical Reports Server (NTRS)

    Goodman, John L.; Walker, Stephen R.

    2009-01-01

    Hubble Space Telescope (HST) servicing, performed by Space Shuttle crews, has contributed to what is arguably one of the most successful astronomy missions ever flown. Both nominal and contingency proximity operations techniques were developed to enable successful servicing, while lowering the risk of damage to HST systems, and improve crew safety. Influencing the development of these techniques were the challenges presented by plume impingement and HST performance anomalies. The design of both the HST and the Space Shuttle was completed before the potential of HST contamination and structural damage by shuttle RCS jet plume impingement was fully understood. Relative navigation during proximity operations has been challenging, as HST was not equipped with relative navigation aids. Since HST reached orbit in 1990, proximity operations design for servicing missions has evolved as insight into plume contamination and dynamic pressure has improved and new relative navigation tools have become available. Servicing missions have provided NASA with opportunities to gain insight into servicing mission design and development of nominal and contingency procedures. The HST servicing experiences and lessons learned are applicable to other programs that perform on-orbit servicing and rendezvous, both human and robotic.

  2. Video-Guidance Design for the DART Rendezvous Mission

    NASA Technical Reports Server (NTRS)

    Ruth, Michael; Tracy, Chisholm

    2004-01-01

    NASA's Demonstration of Autonomous Rendezvous Technology (DART) mission will validate a number of different guidance technologies, including state-differenced GPS transfers and close-approach video guidance. The video guidance for DART will employ NASA/Marshall s Advanced Video Guidance Sensor (AVGS). This paper focuses on the terminal phase of the DART mission that includes close-approach maneuvers under AVGS guidance. The closed-loop video guidance design for DART is driven by a number of competing requirements, including a need for maximizing tracking bandwidths while coping with measurement noise and the need to minimize RCS firings. A range of different strategies for attitude control and docking guidance have been considered for the DART mission, and design decisions are driven by a goal of minimizing both the design complexity and the effects of video guidance lags. The DART design employs an indirect docking approach, in which the guidance position targets are defined using relative attitude information. Flight simulation results have proven the effectiveness of the video guidance design.

  3. Flight data results of estimate fusion for spacecraft rendezvous navigation from shuttle mission STS-69

    NASA Technical Reports Server (NTRS)

    Carpenter, J. Russell; Bishop, Robert H.

    1996-01-01

    A recently developed rendezvous navigation fusion filter that optimally exploits existing distributed filters for rendezvous and GPS navigation to achieve the relative and inertial state accuracies of both in a global solution is utilized here to process actual flight data. Space Shuttle Mission STS-69 was the first mission to date which gathered data from both the rendezvous and Global Positioning System filters allowing, for the first time, a test of the fusion algorithm with real flight data. Furthermore, a precise best estimate of trajectory is available for portions of STS-69, making possible a check on the performance of the fusion filter. In order to successfully carry out this experiment with flight data, two extensions to the existing scheme were necessary: a fusion edit test based on differences between the filter state vectors, and an underweighting scheme to accommodate the suboptimal perfect target assumption made by the Shuttle rendezvous filter. With these innovations, the flight data was successfully fused from playbacks of downlinked and/or recorded measurement data through ground analysis versions of the Shuttle rendezvous filter and a GPS filter developed for another experiment. The fusion results agree with the best estimate of trajectory at approximately the levels of uncertainty expected from the fusion filter's covariance matrix.

  4. Solution to the problem of determining the relative 6 DOF state for spacecraft automated rendezvous and docking

    Microsoft Academic Search

    Phillip C. Calhoun; Richard Dabney

    1995-01-01

    The automated rendezvous and docking of spacecraft requires knowledge of the relative 6 degrees of freedom (6 DOF) between the chase and target spacecraft. A sensor system for estimation of the 6 DOF state is being developed at the Marshall Space Flight Center for the Automated Rendezvous and Capture Project. This sensor employs the use of a charge coupled device

  5. Performance capabilities of a Phase One Automatic Rendezvous and Capture System

    NASA Astrophysics Data System (ADS)

    Kachmar, Peter M.; Polutchko, Robert J.; Matusky, Martin

    This paper presents an analysis of the performance of the existing 'Phase One' AR&C system developed at the C.S. Draper Laboratory for both the rendezvous and proximity operations mission phases. This material has been developed as a result of Draper Laboratory involvement through NASA's Johnson Space Center in the development of the flight proven IGN&C rendezvous systems for Apollo, Skylab, and Shuttle. The development of these systems using Draper computer simulations has required automation of all crew inputs to the IGN&C system and thus provided the unique opportunity to develop and test those system capabilities required for AR&C. This paper expands upon the material in the papers presented by the authors at the NASA Autonomous Rendezvous and Docking Conference held at JSC on August 15-16, 1991.

  6. Automated terminal guidance for a Shuttle rendezvous to Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Olszewski, Oscar W.

    1990-01-01

    An automated terminal guidance for a Shuttle rendezvous based on the Clohessy-Wiltshire (CW) linear equations of relative motion is described. The algorithm guides the Shuttle from the last rendezvous midcourse maneuver (MC4) through docking with Space Station Freedom (SSF). The uniqueness of this algorithm is that it makes it possible to use the CW equations to fly a line-of-sight (LOS) Vbar or Rbar in the final-approach docking phase. The algorithm is made of two parts, in and out-of-plane, and can also be used for station keeping during final approaches. Simulation results of the guidance integrated with the Shuttle's flight control system in the Systems Engineering Simulator (SES) at NASA Johnson are discussed. Plans to add a laser radar docking sensor to the SES and integrate it with the Shuttle's rendezvous navigation are examined.

  7. An Assessment of the Technology of Automated Rendezvous and Capture in Space

    NASA Technical Reports Server (NTRS)

    Polites, M. E.

    1998-01-01

    This paper presents the results of a study to assess the technology of automated rendezvous and capture (AR&C) in space. The outline of the paper is as follows. First, the history of manual and automated rendezvous and capture and rendezvous and dock is presented. Next, the need for AR&C in space is established. Then, today's technology and ongoing technology efforts related to AR&C in space are reviewed. In light of these, AR&C systems are proposed that meet NASA's future needs, but can be developed in a reasonable amount of time with a reasonable amount of money. Technology plans for developing these systems are presented; cost and schedule are included.

  8. Robust rendezvous maneuver point conditions. M.S. Thesis - Massachusetts Inst. of Tech.

    NASA Technical Reports Server (NTRS)

    Fogle, Debra Ann

    1992-01-01

    This study develops rendezvous maneuver point conditions that are robust to one dimensional errors in state estimation and burn execution. Allowing small deviations in the time of intercept provides a degree of freedom that can be used to compensate for these errors. The direction of allowable burn deviation is developed for errors in state estimation and burn execution. The maneuver points for which the error is aligned with the insensitive direction provide excellent rendezvous initiation points. The method is applied to sample rendezvous for vehicles in circular and elliptic orbits. Robust maneuver points are selected and the vehicles' relative motion plotted, demonstrating the validity of the maneuver points. Finally, a graphical illustration of the error focusing effect is demonstrated by means of a Monte Carlo simulation.

  9. Methodology for Developing a Probabilistic Risk Assessment Model of Spacecraft Rendezvous and Dockings

    NASA Technical Reports Server (NTRS)

    Farnham, Steven J., II; Garza, Joel, Jr.; Castillo, Theresa M.; Lutomski, Michael

    2011-01-01

    In 2007 NASA was preparing to send two new visiting vehicles carrying logistics and propellant to the International Space Station (ISS). These new vehicles were the European Space Agency s (ESA) Automated Transfer Vehicle (ATV), the Jules Verne, and the Japanese Aerospace and Explorations Agency s (JAXA) H-II Transfer Vehicle (HTV). The ISS Program wanted to quantify the increased risk to the ISS from these visiting vehicles. At the time, only the Shuttle, the Soyuz, and the Progress vehicles rendezvoused and docked to the ISS. The increased risk to the ISS was from an increase in vehicle traffic, thereby, increasing the potential catastrophic collision during the rendezvous and the docking or berthing of the spacecraft to the ISS. A universal method of evaluating the risk of rendezvous and docking or berthing was created by the ISS s Risk Team to accommodate the increasing number of rendezvous and docking or berthing operations due to the increasing number of different spacecraft, as well as the future arrival of commercial spacecraft. Before the first docking attempt of ESA's ATV and JAXA's HTV to the ISS, a probabilistic risk model was developed to quantitatively calculate the risk of collision of each spacecraft with the ISS. The 5 rendezvous and docking risk models (Soyuz, Progress, Shuttle, ATV, and HTV) have been used to build and refine the modeling methodology for rendezvous and docking of spacecrafts. This risk modeling methodology will be NASA s basis for evaluating the addition of future ISS visiting spacecrafts hazards, including SpaceX s Dragon, Orbital Science s Cygnus, and NASA s own Orion spacecraft. This paper will describe the methodology used for developing a visiting vehicle risk model.

  10. Comparative study of in-cylinder tumble flows in an internal combustion engine using different piston shapes---an insight using particle image velocimetry

    Microsoft Academic Search

    B. Murali Krishna; J. M. Mallikarjuna

    2010-01-01

    This paper deals with the experimental investigations of the in-cylinder tumble flows in a single-cylinder engine with five different piston crown shapes at an engine speed of 1,000 rev\\/min., during suction and compression strokes under motoring conditions using particle image velocimetry. Two-dimensional in-cylinder tumble flow measurements and analysis are carried out in combustion space on a vertical plane passing through

  11. Manned maneuvering unit applications for automated rendezvous and capture

    NASA Astrophysics Data System (ADS)

    Brehm, Donald L.; Cuseo, John A.; Lenda, Joseph A.; Ray, Lex; Whitsett, C. Edward

    Automated Rendezvous and Capture (AR&C) is an important technology to multiple National Aeronautics and Space Administration (NASA) programs and centers. The recent Johnson Spacecraft Center (JSC) AR&C Quality Function Deployment (QFD) has listed on-orbit demonstration of related technologies as a near term priority. Martin Marietta has been evaluating use of the Manned Maneuvering Unit (MMU) for a low cost near term on-orbit demonstration of AR&C technologies such as control algorithms, sensors, and processors as well as system level performance. The MMU Program began in 1979 as the method of repairing the Space Shuttle (STS) Thermal Protection System (the tiles). The units were not needed for this task, but were successfully employed during three Shuttle flights in 1984: a test flight was flown in in February as proof of concept, in April the MMU participated in the Solar Max Repair Mission, and in November the MMU's returned to space to successfully rescue the two errant satellites, Westar and Palapa. In the intervening years, the MMU simulator and MMU Qualification Test Unit (QTU) have been used for Astronaut training and experimental evaluations. The Extra-Vehicular Activities (EVA) Retriever has used the QTU, in an unmanned form, as a free-flyer on the Johnson Space Center (JSC) Precision Air Bearing Floor (PABF). Currently, the MMU is undergoing recertification for flight. The two flight units were removed from storage in September, 1991 and evaluation tests were performed. The tests demonstrated that the units are in good shape with no discrepancies that would preclude further use. The Return to Flight effort is currently clearing up recertification issues and evaluating the design against the present Shuttle environments.

  12. Manned maneuvering unit applications for automated rendezvous and capture

    NASA Technical Reports Server (NTRS)

    Brehm, Donald L.; Cuseo, John A.; Lenda, Joseph A.; Ray, Lex; Whitsett, C. Edward

    1991-01-01

    Automated Rendezvous and Capture (AR&C) is an important technology to multiple National Aeronautics and Space Administration (NASA) programs and centers. The recent Johnson Spacecraft Center (JSC) AR&C Quality Function Deployment (QFD) has listed on-orbit demonstration of related technologies as a near term priority. Martin Marietta has been evaluating use of the Manned Maneuvering Unit (MMU) for a low cost near term on-orbit demonstration of AR&C technologies such as control algorithms, sensors, and processors as well as system level performance. The MMU Program began in 1979 as the method of repairing the Space Shuttle (STS) Thermal Protection System (the tiles). The units were not needed for this task, but were successfully employed during three Shuttle flights in 1984: a test flight was flown in in February as proof of concept, in April the MMU participated in the Solar Max Repair Mission, and in November the MMU's returned to space to successfully rescue the two errant satellites, Westar and Palapa. In the intervening years, the MMU simulator and MMU Qualification Test Unit (QTU) have been used for Astronaut training and experimental evaluations. The Extra-Vehicular Activities (EVA) Retriever has used the QTU, in an unmanned form, as a free-flyer on the Johnson Space Center (JSC) Precision Air Bearing Floor (PABF). Currently, the MMU is undergoing recertification for flight. The two flight units were removed from storage in September, 1991 and evaluation tests were performed. The tests demonstrated that the units are in good shape with no discrepancies that would preclude further use. The Return to Flight effort is currently clearing up recertification issues and evaluating the design against the present Shuttle environments.

  13. A Comparison of Trajectory Optimization Methods for the Impulsive Minimum Fuel Rendezvous Problem

    NASA Technical Reports Server (NTRS)

    Hughes, Steven P.; Mailhe, Laurie M.; Guzman, Jose J.

    2002-01-01

    In this paper we present a comparison of optimization approaches to the minimum fuel rendezvous problem. Both indirect and direct methods are compared for a variety of test cases. The indirect approach is based on primer vector theory. The direct approaches are implemented numerically and include Sequential Quadratic Programming (SQP), Quasi-Newton, Simplex, Genetic Algorithms, and Simulated Annealing. Each method is applied to a variety of test cases including, circular to circular coplanar orbits, LEO to GEO, and orbit phasing in highly elliptic orbits. We also compare different constrained optimization routines on complex orbit rendezvous problems with complicated, highly nonlinear constraints.

  14. Halley comet rendezvous with a SEPS vehicle. [Solar Electric Propulsion System

    NASA Technical Reports Server (NTRS)

    Burrows, R. R.

    1978-01-01

    An analysis of the performance of a Solar Electric Propulsion System (SEPS) vehicle rendezvousing with Halley's comet just prior to its Frebruary 1986 perihelion is described. A calculus of variations mathematical formulation is used to maximize Halley arrival mass while giving effect to the influence of solar array size, launch date, arrival date, and insertion hyperbolic excess velocity. Numerical sensitivity relief, thrust system modeling, trajectory characteristics and ion engine operating conditions are discussed and illustrated. Results indicate a rendezvous is feasible with a minimal advance in solar cell and ion engine technology.

  15. Gemini Range and Range Rate Measuring System

    Microsoft Academic Search

    Martin G. Woolfson

    1963-01-01

    To complete the terminal phase of a space rendezvous mission, it is essential that accurate indications of target vehicle range and relative range rate be presented to the astronauts commanding the chaser vehicle. The indicator characteristics and the method of data presentation assume prime importance in compliance with the above. Therefore, a discussion is given of the logical development and

  16. Drill Holes and Predation Traces versus Abrasion-Induced Artifacts Revealed by Tumbling Experiments

    PubMed Central

    Gorzelak, Przemys?aw; Salamon, Mariusz A.; Trz?siok, Dawid; Nied?wiedzki, Robert

    2013-01-01

    Drill holes made by predators in prey shells are widely considered to be the most unambiguous bodies of evidence of predator-prey interactions in the fossil record. However, recognition of traces of predatory origin from those formed by abiotic factors still waits for a rigorous evaluation as a prerequisite to ascertain predation intensity through geologic time and to test macroevolutionary patterns. New experimental data from tumbling various extant shells demonstrate that abrasion may leave holes strongly resembling the traces produced by drilling predators. They typically represent singular, circular to oval penetrations perpendicular to the shell surface. These data provide an alternative explanation to the drilling predation hypothesis for the origin of holes recorded in fossil shells. Although various non-morphological criteria (evaluation of holes for non-random distribution) and morphometric studies (quantification of the drill hole shape) have been employed to separate biological from abiotic traces, these are probably insufficient to exclude abrasion artifacts, consequently leading to overestimate predation intensity. As a result, from now on, we must adopt more rigorous criteria to appropriately distinguish abrasion artifacts from drill holes, such as microstructural identification of micro-rasping traces. PMID:23505530

  17. Active Brownian Particles and Run-and-Tumble Particles: a Comparative Study

    E-print Network

    A. P. Solon; M. E. Cates; J. Tailleur

    2015-04-28

    Active Brownian particles (ABPs) and Run-and-Tumble particles (RTPs) both self-propel at fixed speed $v$ along a body-axis ${\\bf u}$ that reorients either through slow angular diffusion (ABPs) or sudden complete randomisation (RTPs). We compare the physics of these two model systems both at microscopic and macroscopic scales. Using exact results for their steady-state distribution in the presence of external potentials, we show that they both admit the same effective equilibrium regime perturbatively that breaks down for stronger external potentials, in a model-dependent way. In the presence of collisional repulsions such particles slow down at high density: their propulsive effort is unchanged, but their average speed along ${\\bf u}$ becomes $v(\\rho) field description in which particles are ghost-like and have no collisions, but swim at a variable speed $v$ that is an explicit function or functional of the density $\\rho$. We give numerical evidence that the recently shown equivalence of the fluctuating hydrodynamics of ABPs and RTPs in this case, which we detail here, extends to microscopic models of ABPs and RTPs interacting with repulsive forces.

  18. Six degree of freedom simulation system for evaluating automated rendezvous and docking spacecraft

    Microsoft Academic Search

    Kenneth H. Rourke; Roy K. Tsugawa

    1991-01-01

    Future logistics supply and servicing vehicles such as cargo transfer vehicles (CTV) must have full 6 degree of freedom (6DOF) capability in order to perform requisite rendezvous, proximity operations, and capture operations. The design and performance issues encountered when developing a 6DOF maneuvering spacecraft are very complex with subtle interactions which are not immediately obvious or easily anticipated. In order

  19. The Rendezvous Algorithm: Multiclass Semi-Supervised Learning with Markov Random Walks

    E-print Network

    Ghahramani, Zoubin

    The Rendezvous Algorithm: Multiclass Semi-Supervised Learning with Markov Random Walks Arik Azran a transition probability matrix P for a Markov random walk between them. The algorithm associates each point of the Markov random walk, and the probability of each particle to be absorbed by the differ- ent labeled points

  20. Sensory fusion for planetary surface robotic navigation, rendezvous, and manipulation operations

    NASA Technical Reports Server (NTRS)

    Huntsberger, T.; Cheng, Y.; Baumgartner, E. T.; Robinson, M.; Schenker, P. S.

    2003-01-01

    This paper reports some of the ongoing work at JPL in the areas of autonomous sensory fusion of both raw and derived inputs for better localization during long traverses, precision rendezvous operations with both labeled and unlabeled targets, and precision manipulation of targets.

  1. Peer-to-Peer Refuelling within a Satellite Constellation Part II: Nonzero-Cost Rendezvous Case

    E-print Network

    Tsiotras, Panagiotis

    Peer-to-Peer Refuelling within a Satellite Constellation Part II: Nonzero-Cost Rendezvous Case in a constellation. It is assumed that there is no fuel delivered to the constellation externally. Instead, the satellites in the constellation are assumed to be capable of refuelling each other. The cost

  2. Peer-to-Peer Refuelling within a Satellite Constellation Part I: Zero-Cost Rendezvous Case

    E-print Network

    Tsiotras, Panagiotis

    Peer-to-Peer Refuelling within a Satellite Constellation Part I: Zero-Cost Rendezvous Case Haijun in a constellation. The satellites in the constellation are assumed to be capable of refu- elling each other in the constellation after a given period. It is shown that the problem of equalizing the fuel among the satellites can

  3. Multiple Agents RendezVous In a Ring in Spite of a Black Hole

    E-print Network

    Santoro, Nicola

    Multiple Agents RendezVous In a Ring in Spite of a Black Hole Stefan Dobrev Paola Flocchini this problem when in the network there is a black hole: a stationary process located at a node that destroys any incoming agent without leaving any trace. The presence of the black hole makes it clearly

  4. Space Shuttle Program: Automatic rendezvous, proximity operations, and capture (category 3)

    Microsoft Academic Search

    William L. Jackson; Roscoe Lee; Richard E. Eick; J. V. Hallstrom; Harry K. Hiers; John P. McManamen; Oscar W. Olszewski; Joseph L. Prather; D. L. Rue; Karl J. Zimmer

    1991-01-01

    The NASA Johnson Space Center is actively pursuing the development and demonstration of capabilities for automatic rendezvous, proximity operations, and capture (AR&C) using the Space Shuttle as the active vehicle. This activity combines the technologies, expertise, tools, and facilities of the JSC Tracking and Communications Division (EE), Navigation, Control and Aeronautics Division (EG), Automation and Robotics Division (ER), and Structures

  5. An analytic approach to optimal rendezvous using Clohessy-Wiltshire equations

    NASA Technical Reports Server (NTRS)

    Jezewski, D. J.; Donaldson, J. D.

    1979-01-01

    An analytic approach is used to obtain the optimal solution time that minimizes the sum of the two applied impulses necessary to rendezvous for the Clohessy-Wiltshire equations. A plume impingement inequality constraint on the solution is examined, and an optimal policy is developed. Numerical tests are conducted to verify the analysis and to illustrate the optimal solution algorithm.

  6. Continuous wave (CW) diode laser instrumentation for rendezvous and docking maneuvers in geosynchronous orbits

    Microsoft Academic Search

    G. Sepp

    1984-01-01

    A rendezvous and docking (RVD) laser radar system onboard a chaser spacecraft is described. The target spacecraft is equipped with several docking ports and retroreflectors. The RVD procedure from the initial target acquisition until docking, including methods of measuring range, velocity, relative orientation between chaser and target, docking port identification, and field of view explosion during the last meters is

  7. Advanced opto-electronical sensors for autonomous Rendezvous\\/Docking and proximity operations in space

    Microsoft Academic Search

    B. Kunkel; R. Lutz; S. Manhart

    1986-01-01

    Experimental work on three types of candidate optical sensors for rendezvous and docking tasks, active laser diode radars, CCD cameras and position detector sensors, plus a combination of these is presented. The results obtained up to now with a test lab (including motion simulation) make each of them a promising candidate for this kind of application for different range regimes.

  8. Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation

    Microsoft Academic Search

    J. K. Miller; P. J. Antreasian; J. Georgini; W. M. Owen; B. G. Williams; D. K. Yeomans

    1995-01-01

    Navigation of the orbit phase of the Near Earth steroid Rendezvous (NEAR) mission will re,quire determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was known about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light

  9. Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

    Microsoft Academic Search

    James A. Bilbro

    1991-01-01

    The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at

  10. Determination of Eros physical parameters for near Earth asteroid rendezvous orbit phase navigation

    Microsoft Academic Search

    J. K. Miller; P. J. Antreasian; R. W. Gaskell; J. D. Giorgini; C. E. Helfrich; W. M. Owen; B. G. Williams; D. K. Yeomanst

    1999-01-01

    Navigation of the orbit phase of the Near Earth Asteroid Rendezvous (NEAR) mission will require determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was kno-yn about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light

  11. Proximity Operations for Space Situational Awareness Spacecraft Rendezvous and Maneuvering using Numerical Simulations and Fuzzy Logic

    Microsoft Academic Search

    Timothy Carrico; T. Langster; J. Carrico; S. Alfano; M. Loucks; D. Vallado

    2006-01-01

    The authors present several spacecraft rendezvous and close proximity maneuvering techniques modeled with a high-precision numerical integrator using full force models and closed loop control with a Fuzzy Logic intelligent controller to command the engines. The authors document and compare the maneuvers, fuel use, and other parameters. This paper presents an innovative application of an existing capability to design, simulate

  12. Rendezvous and Docking Strategy for Crewed Segment of the Asteroid Redirect Mission

    NASA Technical Reports Server (NTRS)

    Hinkel, Heather D.; Cryan, Scott P.; D'Souza, Christopher; Dannemiller, David P.; Brazzel, Jack P.; Condon, Gerald L.; Othon, William L.; Williams, Jacob

    2014-01-01

    This paper will describe the overall rendezvous, proximity operations and docking (RPOD) strategy in support of the Asteroid Redirect Crewed Mission (ARCM), as part of the Asteroid Redirect Mission (ARM). The focus of the paper is on the crewed mission phase of ARM, starting with the establishment of Orion in the Distant Retrograde Orbit (DRO) and ending with docking to the Asteroid Redirect Vechicle (ARV). The paper will detail the sequence of maneuvers required to execute the rendezvous and proximity operations mission phases along with the on-board navigation strategies, including the final approach phase. The trajectories to be considered will include target vehicles in a DRO. The paper will also discuss the sensor requirements for rendezvous and docking and the various trade studies associated with the final sensor selection. Building on the sensor requirements and trade studies, the paper will include a candidate sensor concept of operations, which will drive the selection of the sensor suite; concurrently, it will be driven by higher level requirements on the system, such as crew timeline constraints and vehicle consummables. This paper will address how many of the seemingly competing requirements will have to be addressed to create a complete system and system design. The objective is to determine a sensor suite and trajectories that enable Orion to successfully rendezvous and dock with a target vehicle in trans lunar space. Finally, the paper will report on the status of a NASA action to look for synergy within RPOD, across the crewed and robotic asteroid missions.

  13. The Direction of Synthetic Actors in the Film RendezVous a Montreal

    Microsoft Academic Search

    N. Magnenat-Thalmann; Daniel Thalmann

    1987-01-01

    This article describes how the synthetic actors Marilyn Monroe and Humphrey Bogart were directed in the film Rendez-vous a Montreal, using the Human Factory software. Innovative points are emphasized. The recreation of famous persons and reconstitution of their personalities, as well as the corresponding animation, are considered from an artistic point of view. Technical points discussed are personalized expressions, abstract

  14. Security-Enhanced Virtual Channel Rendezvous Algorithm for Dynamic Spectrum Access Wireless Networks

    Microsoft Academic Search

    Liangping Ma; Chien-Chung Shen

    2008-01-01

    This paper presents the security-enhanced virtual channel rendezvous (SVCR) algorithm to improve the robustness of a dynamic spectrum access (DSA) network against attacks from power-constrained smart jammers. The jammer is smart in the sense that it senses and analyzes the spectrum activities of the DSA network before launching an attack. SVCR does not use a common control channel. In addition,

  15. Diffusion, sedimentation equilibrium, and harmonic trapping of run-and-tumble nanoswimmers.

    PubMed

    Wang, Zhengjia; Chen, Hsuan-Yi; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2014-05-14

    The diffusion of self-propelling nanoswimmers is explored by dissipative particle dynamics in which a nanoswimmer swims by forming an instantaneous force dipole with one of its nearest neighboring solvent beads. Our simulations mimic run-and-tumble behavior by letting the swimmer run for a time ?, then it randomly changes its direction for the next run period. Our simulations show that the swimming speed (?(a)) of a nanoswimmer is proportional to the propulsion force and the mobility of a pusher is the same as that of a puller. The effective diffusivity is determined by three methods: mean squared displacement, velocity autocorrelation function, and sedimentation equilibrium. The active colloid undergoes directed propulsion at short time scales but changes to random motion at long time scales. The velocity autocorrelation function decreases with time and becomes zero beyond the run time. Under gravity, the concentration profile of active colloids follows Boltzmann distribution with a sedimentation length consistent with that acquired from the drift-diffusion equation. In our simulation, all three methods yield the same result, the effective diffusivity of an active colloid is the sum of the diffusivity of a passive colloid and ?(a)²?/6. When the active colloids are confined by a harmonic well, they are trapped within a confinement length defined by the balance between the swimmer active force and restoring force of the well. When the confinement length is large compared to the run length, the stationary density profile follows the Boltzmann distribution. However, when the run length exceeds the confinement length, the density distribution is no longer described by Boltzmann distribution, instead we found a bimodal distribution. PMID:24718999

  16. Rendezvous Planning in Mobility-assisted Wireless Sensor Networks Guoliang Xing; Tian Wang; Zhihui Xie; Weijia Jia

    E-print Network

    without trav- eling long distances, which can achieve a desirable balance between network energy saving at a time without traveling a long distance, which achiRendezvous Planning in Mobility-assisted Wireless Sensor Networks Guoliang Xing; Tian Wang; Zhihui

  17. Guidance and Navigation for Rendezvous and Proximity Operations with a Non-Cooperative Spacecraft at Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Barbee, Brent William; Carpenter, J. Russell; Heatwole, Scott; Markley, F. Landis; Moreau, Michael; Naasz, Bo J.; VanEepoel, John

    2010-01-01

    The feasibility and benefits of various spacecraft servicing concepts are currently being assessed, and all require that the servicer spacecraft perform rendezvous, proximity, and capture operations with the target spacecraft to be serviced. Many high-value spacecraft, which would be logical targets for servicing from an economic point of view, are located in geosynchronous orbit, a regime in which autonomous rendezvous and capture operations are not commonplace. Furthermore, existing GEO spacecraft were not designed to be serviced. Most do not have cooperative relative navigation sensors or docking features, and some servicing applications, such as de-orbiting of a non-functional spacecraft, entail rendezvous and capture with a spacecraft that may be non-functional or un-controlled. Several of these challenges have been explored via the design of a notional mission in which a nonfunctional satellite in geosynchronous orbit is captured by a servicer spacecraft and boosted into super-synchronous orbit for safe disposal. A strategy for autonomous rendezvous, proximity operations, and capture is developed, and the Orbit Determination Toolbox (ODTBX) is used to perform a relative navigation simulation to assess the feasibility of performing the rendezvous using a combination of angles-only and range measurements. Additionally, a method for designing efficient orbital rendezvous sequences for multiple target spacecraft is utilized to examine the capabilities of a servicer spacecraft to service multiple targets during the course of a single mission.

  18. Six degree of freedom simulation system for evaluating automated rendezvous and docking spacecraft

    NASA Technical Reports Server (NTRS)

    Rourke, Kenneth H.; Tsugawa, Roy K.

    1991-01-01

    Future logistics supply and servicing vehicles such as cargo transfer vehicles (CTV) must have full 6 degree of freedom (6DOF) capability in order to perform requisite rendezvous, proximity operations, and capture operations. The design and performance issues encountered when developing a 6DOF maneuvering spacecraft are very complex with subtle interactions which are not immediately obvious or easily anticipated. In order to deal with these complexities and develop robust maneuvering spacecraft designs, a simulation system and associated family of tools are used at TRW for generating and validating spacecraft performance requirements and guidance algorithms. An overview of the simulator and tools is provided. These are used by TRW for autonomous rendezvous and docking research projects including CTV studies.

  19. Low-Cost Innovation in Spaceflight: The Near Earth Asteroid Rendezvous (NEAR) Shoemaker Mission

    NASA Technical Reports Server (NTRS)

    McCurdy, Howard E.

    2005-01-01

    On a spring day in 1996, at their research center in the Maryland countryside, representatives from the Johns Hopkins University Applied Physics Laboratory (APL) presented Administrator Daniel S. Goldin of the National Aeronautics and Space Administration (NASA) with a check for $3.6 million. 1 Two and a half years earlier, APL officials had agreed to develop a spacecraft capable of conducting an asteroid rendezvous and to do so for slightly more than $122 million. This was a remarkably low sum for a spacecraft due to conduct a planetaryclass mission. By contrast, the Mars Observer spacecraft launched in 1992 for an orbital rendezvous with the red planet had cost $479 million to develop, while the upcoming Cassini mission to Saturn required a spacecraft whose total cost was approaching $1.4 billion. In an Agency accustomed to cost overruns on major missions, the promise to build a planetary-class spacecraft for about $100 million seemed excessively optimistic.

  20. The asteroid rendezvous spacecraft. An adaptation study of TIROS/DMSP technology

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The feasibility of using the TIROS/DMSP Earth orbiting meteorological satellite in application to a near Earth asteroid rendezvous mission. System and subsystems analysis was carried out to develop a configuration of the spacecraft suitable for this mission. Mission analysis studies were also done and maneuver/rendezvous scenarios developed for baseline missions to both Anteros and Eros. The fact that the Asteroid mission is the most complex of the Pioneer class missions currently under consideration notwithstanding, the basic conclusion very strongly supports the suitability of the basic TIROS bus for this mission in all systems and subsystems areas, including science accommodation. Further, the modifications which are required due to the unique mission are very low risk and can be accomplished readily. The key issue is that in virtually every key subsystem, the demands of the Asteroid mission are a subset of the basic meteorological satellite mission. This allows a relatively simple reconfiguration to be accomplished without a major system redesign.

  1. SIMONE: near-Earth asteroid rendezvous microsatellites with solar-electric propulsion

    NASA Astrophysics Data System (ADS)

    Ball, Andrew J.; Green, Simon F.; Wells, Nigel S.

    2002-11-01

    The SIMONE mission proposal is led by QinetiQ, with scientific aspects led by the Open University's Planetary and Space Science Research Institute. Currently the focus of an ESA-funded study, the concept is to help understand the diversity of the NEO population using a fleet of microsatellite-class (~120 kg) interplanetary spacecraft. These will individually rendezvous with specific Near-Earth Objects of interest (together representing a number of important spectral and photometric types) to perform 'up close' measurements of key physical, morphological and compositional features. The ?V capability of the solar-electric-propelled spacecraft should make a wide range of objects accessible for rendezvous, or at least a sequence of resonant flybys. The wide-ranging dataset produced will be important for risk assessment and studies of possible mitigation approaches, as well as for science.

  2. Optimal impulsive time-fixed orbital rendezvous and interception with path constraints

    NASA Technical Reports Server (NTRS)

    Taur, D.-R.; Prussing, J. E.; Coverstone-Carroll, V.

    1990-01-01

    Minimum-fuel, impulsive, time-fixed solutions are obtained for the problem of orbital rendezvous and interception with interior path constraints. Transfers between coplanar circular orbits in an inverse-square gravitational field are considered, subject to a circular path constraint representing a minimum or maximum permissible orbital radius. Primer vector theory is extended to incorporate path constraints. The optimal number of impulses, their times and positions, and the presence of initial or final coasting arcs are determined. The existence of constraint boundary arcs and boundary points is investigated as well as the optimality of a class of singular arc solutions. To illustrate the complexities introduced by path constraints, an analysis is made of optimal rendezvous in field-free space subject to a minimum radius constraint.

  3. Comparative study of in-cylinder tumble flows in an internal combustion engine using different piston shapes—an insight using particle image velocimetry

    Microsoft Academic Search

    B. Murali Krishna; J. M. Mallikarjuna

    2010-01-01

    This paper deals with the experimental investigations of the in-cylinder tumble flows in a single-cylinder engine with five\\u000a different piston crown shapes at an engine speed of 1,000 rev\\/min., during suction and compression strokes under motoring\\u000a conditions using particle image velocimetry. Two-dimensional in-cylinder tumble flow measurements and analysis are carried\\u000a out in combustion space on a vertical plane passing through cylinder

  4. Target Localization from 3D data for On-Orbit Autonomous Rendezvous & Docking

    Microsoft Academic Search

    S. Ruel; T. Luu; M. Anctil; S. Gagnon

    2008-01-01

    Neptec has developed a vision system for autonomous on-orbit rendezvous and docking that does not require the use of cooperative markers on the target spacecraft. The system uses an active TriDAR 3D sensor and efficient model based tracking algorithms to provide 6 degree of freedom (6DOF) relative pose information in realtime. The TriDAR (triangulation + LIDAR) sensing technology combines triangulation

  5. Analytical Evaluation of a Method of Midcourse Guidance for Rendezvous with Earth Satellites

    NASA Technical Reports Server (NTRS)

    Eggleston, John M.; Dunning, Robert S.

    1961-01-01

    A digital-computer simulation was made of the midcourse or ascent phase of a rendezvous between a ferry vehicle and a space station. The simulation involved a closed-loop guidance system in which both the relative position and relative velocity between ferry and station are measured (by simulated radar) and the relative-velocity corrections required to null the miss distance are computed and applied. The results are used to study the effectiveness of a particular set of guidance equations and to study the effects of errors in the launch conditions and errors in the navigation data. A number of trajectories were investigated over a variety of initial conditions for cases in which the space station was in a circular orbit and also in an elliptic orbit. Trajectories are described in terms of a rotating coordinate system fixed in the station. As a result of this study the following conclusions are drawn. Successful rendezvous can be achieved even with launch conditions which are substantially less accurate than those obtained with present-day techniques. The average total-velocity correction required during the midcourse phase is directly proportional to the radar accuracy but the miss distance is not. Errors in the time of booster burnout or in the position of the ferry at booster burnout are less important than errors in the ferry velocity at booster burnout. The use of dead bands to account for errors in the navigational (radar) equipment appears to depend upon a compromise between the magnitude of the velocity corrections to be made and the allowable miss distance at the termination of the midcourse phase of the rendezvous. When approximate guidance equations are used, there are limits on their accuracy which are dependent on the angular distance about the earth to the expected point of rendezvous.

  6. Laser radar instrument for the Near-Earth Asteroid Rendezvous (NEAR) mission

    Microsoft Academic Search

    Timothy D. Cole; Mark T. Boies; Ashruf S. El-Dinary

    1996-01-01

    In 1999 after a 3-year transit, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft will enter a low-altitude (approximately 50 km) orbit about the asteroid, 433 Eros. Five instruments, including a laser radar, will operate continuously during the one-year orbit at Eros. The NEAR laser rangefinder (NLR), developed at the Applied Physics Laboratory (APL), is a robust rangefinder and the first spaceborne

  7. Laser rangefinder for the near-earth asteroid rendezvous (NEAR) mission

    Microsoft Academic Search

    Timothy D. Cole; Mark T. Boies; Ashruf S. El-Dinary; R. Alan Reiter; Daniel E. Rodriguez; Robert J. Heins; Binh Q. Le; Robert C. Moore; Michael G. Grote; Charles Culpepper; Lee Stillman

    1995-01-01

    The near-earth asteroid rendezvous (NEAR) mission is the first of the NASA discovery programs. Discovery-class programs emphasize small, low-cost, quick turnaround space missions that provide significant science returns. The NEAR spacecraft and ground control system are currently being developed and tested at the Applied Physics Laboratory (APL). The NEAR spacecraft will orbit, 433 Eros, possibly the most studied of the

  8. Modeling, simulation, testing, and verification of the Orbital Express Autonomous Rendezvous and Capture Sensor System (ARCSS)

    NASA Astrophysics Data System (ADS)

    Leinz, Manny R.; Chen, Chih-Tsai; Scott, Peter; Gaumer, William; Sabasteanski, Peter; Beaven, Michael

    2008-04-01

    The Orbital Express Autonomous Rendezvous and Capture Sensor System (ARCSS) ALONG WITH ITS Vision-based Software for Track, Attitude and Ranging (Vis-STAR) provided relative target position and attitude measurements for guidance and relative navigation during autonomous vehicle proximity operations. The use of computer and physical models during simulation, ground testing and verification of ARCSS imaging camera and software performance prior to and during on-orbit operations is discussed.

  9. New form for the optimal rendezvous equations near a Keplerian orbit

    NASA Astrophysics Data System (ADS)

    Carter, Thomas E.

    1990-02-01

    The original form of the optimal rendezvous equations near a Keplerian orbit is presently modified by replacing the integral I(theta) with the related integral J(theta), which removes all previously encountered singularities and computational instabilities. The solution thus obtained is identical for hyperbolic, parabolic, and noncircular elliptic orbits; the particular case, however, determines the character of the closed-form evaluation of J(theta).

  10. A Ground Testbed to Advance US Capability in Autonomous Rendezvous and Docking Project

    NASA Technical Reports Server (NTRS)

    D'Souza, Chris

    2014-01-01

    This project will advance the Autonomous Rendezvous and Docking (AR&D) GNC system by testing it on hardware, particularly in a flight processor, with a goal of testing it in IPAS with the Waypoint L2 AR&D scenario. The entire Agency supports development of a Commodity for Autonomous Rendezvous and Docking (CARD) as outlined in the Agency-wide Community of Practice whitepaper entitled: "A Strategy for the U.S. to Develop and Maintain a Mainstream Capability for Automated/Autonomous Rendezvous and Docking in Low Earth Orbit and Beyond". The whitepaper establishes that 1) the US is in a continual state of AR&D point-designs and therefore there is no US "off-the-shelf" AR&D capability in existence today, 2) the US has fallen behind our foreign counterparts particularly in the autonomy of AR&D systems, 3) development of an AR&D commodity is a national need that would benefit NASA, our commercial partners, and DoD, and 4) an initial estimate indicates that the development of a standardized AR&D capability could save the US approximately $60M for each AR&D project and cut each project's AR&D flight system implementation time in half.

  11. The Data Transfer Kit: A geometric rendezvous-based tool for multiphysics data transfer

    SciTech Connect

    Slattery, S. R.; Wilson, P. P. H. [Department of Engineering Physics, University of Wisconsin - Madison, 1500 Engineering Dr., Madison, WI 53706 (United States); Pawlowski, R. P. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185 (United States)

    2013-07-01

    The Data Transfer Kit (DTK) is a software library designed to provide parallel data transfer services for arbitrary physics components based on the concept of geometric rendezvous. The rendezvous algorithm provides a means to geometrically correlate two geometric domains that may be arbitrarily decomposed in a parallel simulation. By repartitioning both domains such that they have the same geometric domain on each parallel process, efficient and load balanced search operations and data transfer can be performed at a desirable algorithmic time complexity with low communication overhead relative to other types of mapping algorithms. With the increased development efforts in multiphysics simulation and other multiple mesh and geometry problems, generating parallel topology maps for transferring fields and other data between geometric domains is a common operation. The algorithms used to generate parallel topology maps based on the concept of geometric rendezvous as implemented in DTK are described with an example using a conjugate heat transfer calculation and thermal coupling with a neutronics code. In addition, we provide the results of initial scaling studies performed on the Jaguar Cray XK6 system at Oak Ridge National Laboratory for a worse-case-scenario problem in terms of algorithmic complexity that shows good scaling on 0(1 x 104) cores for topology map generation and excellent scaling on 0(1 x 105) cores for the data transfer operation with meshes of O(1 x 109) elements. (authors)

  12. The Space Operations Simulation Center (SOSC) and Closed-loop Hardware Testing for Orion Rendezvous System Design

    NASA Technical Reports Server (NTRS)

    D'Souza, Christopher; Milenkovich, Zoran; Wilson, Zachary; Huich, David; Bendle, John; Kibler, Angela

    2011-01-01

    The Space Operations Simulation Center (SOSC) at the Lockheed Martin (LM) Waterton Campus in Littleton, Colorado is a dynamic test environment focused on Autonomous Rendezvous and Docking (AR&D) development testing and risk reduction activities. The SOSC supports multiple program pursuits and accommodates testing Guidance, Navigation, and Control (GN&C) algorithms for relative navigation, hardware testing and characterization, as well as software and test process development. The SOSC consists of a high bay (60 meters long by 15.2 meters wide by 15.2 meters tall) with dual six degree-of-freedom (6DOF) motion simulators and a single fixed base 6DOF robot. The large testing area (maximum sensor-to-target effective range of 60 meters) allows for large-scale, flight-like simulations of proximity maneuvers and docking events. The facility also has two apertures for access to external extended-range outdoor target test operations. In addition, the facility contains four Mission Operations Centers (MOCs) with connectivity to dual high bay control rooms and a data/video interface room. The high bay is rated at Class 300,000 (. 0.5 m maximum particles/m3) cleanliness and includes orbital lighting simulation capabilities.

  13. Androgen and the Development of Human Sex-Typical Behavior: Rough-and-Tumble Play and Sex of Preferred Playmates in Children with Congenital Adrenal Hyperplasia (CAH).

    ERIC Educational Resources Information Center

    Hines, Melissa; Kaufman, Francine R.

    1994-01-01

    Examined the rough-and-tumble play and gender of preferred playmates in three- to eight-year olds with congenital adrenal hyperplasia (CAH)--hypothesized to masculinize behaviors that show sex differences--and in unaffected three- to eight-year-old relatives. Found that CAH girls did not exhibit increased levels of masculine behavior when compared…

  14. A novel approach to heat transfer enhancement using trapezoid shaped spiral strips to promote tumble and swirl in a slot shaped channel used in heat exchangers 

    E-print Network

    Segura, D.; Acharya, S.

    2012-01-01

    Heat transfer results for a given slot shaped channel with a 3:1 aspect ratio are presented using various configurations of a trapezoid shaped spiral wound strips to enhance swirl and tumble motion in the channel. The Reynolds numbers investigated...

  15. THE NEAR-EARTH ASTEROID RENDEZVOUS LASER ALTIMETER T. D. COLE, M. T. BOIES, A. S. EL-DINARY and A. CHENG

    E-print Network

    Zuber, Maria

    THE NEAR-EARTH ASTEROID RENDEZVOUS LASER ALTIMETER T. D. COLE, M. T. BOIES, A. S. EL-DINARY and A transit, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft will enter a low-altitude orbit around. Developed at the Applied Physics Laboratory (APL), the NLR instrument is a direct-detection laser radar

  16. Principles Involved in the LM Rendezvous Radar Redundant Gyro System

    Microsoft Academic Search

    John Dubbuyr

    1970-01-01

    For typical failure rates the probability of two or more of four gyros failing is very much less than one or both of two. Thus, a single redundancy system of four gyros greatly enhances system reliability. The orientation of the sensitive axes of four gyros is specified and means of generating outputs dependent only on gyro inconsistencies are defined. The

  17. Study on Performance of Integration Control by Man and Machine in Stage of Final Approaching for Spaceship Rendezvous and Docking

    NASA Astrophysics Data System (ADS)

    Zhou, Qianxiang; Liu, Zhongqi

    With the development of manned space technology, space rendezvous and docking (RVD) technology will play a more and more important role. The astronauts’ participation in a final close period of man-machine combination control is an important way of RVD technology. Spacecraft RVD control involves control problem of a total of 12 degrees of freedom (location) and attitude which it relative to the inertial space the orbit. Therefore, in order to reduce the astronauts’ operation load and reduce the security requirements to the ground station and achieve an optimal performance of the whole man-machine system, it is need to study how to design the number of control parameters of astronaut or aircraft automatic control system. In this study, with the laboratory conditions on the ground, a method was put forward to develop an experimental system in which the performance evaluation of spaceship RVD integration control by man and machine could be completed. After the RVD precision requirements were determined, 26 male volunteers aged 20-40 took part in the performance evaluation experiments. The RVD integration control success rates and total thruster ignition time were chosen as evaluation indices. Results show that if less than three RVD parameters control tasks were finished by subject and the rest of parameters control task completed by automation, the RVD success rate would be larger than eighty-eight percent and the fuel consumption would be optimized. In addition, there were two subjects who finished the whole six RVD parameters control tasks by enough train. In conclusion, if the astronauts' role should be integrated into the RVD control, it was suitable for them to finish the heading, pitch and roll control in order to assure the man-machine system high performance. If astronauts were needed to finish all parameter control, two points should be taken into consideration, one was enough fuel and another was enough long operation time.

  18. Application of neural networks to autonomous rendezvous and docking of space vehicles

    NASA Technical Reports Server (NTRS)

    Dabney, Richard W.

    1992-01-01

    NASA-Marshall has investigated the feasibility of numerous autonomous rendezvous and docking (ARD) candidate techniques. Neural networks have been studied as a viable basis for such systems' implementation, due to their intrinsic representation of such nonlinear functions as those for which analytical solutions are either difficult or nonexistent. Neural networks are also able to recognize and adapt to changes in their dynamic environment, thereby enhancing redundancy and fault tolerance. Outstanding performance has been obtained from ARD azimuth, elevation, and roll networks of this type.

  19. NASA Automated Rendezvous and Capture Review. A compilation of the abstracts

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This document presents a compilation of abstracts of papers solicited for presentation at the NASA Automated Rendezvous and Capture Review held in Williamsburg, VA on November 19-21, 1991. Due to limitations on time and other considerations, not all abstracts could be presented during the review. The organizing committee determined however, that all abstracts merited availability to all participants and represented data and information reflecting state-of-the-art of this technology which should be captured in one document for future use and reference. The organizing committee appreciates the interest shown in the review and the response by the authors in submitting these abstracts.

  20. Embedded Relative Navigation Sensor Fusion Algorithms for Autonomous Rendezvous and Docking Missions

    NASA Technical Reports Server (NTRS)

    DeKock, Brandon K.; Betts, Kevin M.; McDuffie, James H.; Dreas, Christine B.

    2008-01-01

    bd Systems (a subsidiary of SAIC) has developed a suite of embedded relative navigation sensor fusion algorithms to enable NASA autonomous rendezvous and docking (AR&D) missions. Translational and rotational Extended Kalman Filters (EKFs) were developed for integrating measurements based on the vehicles' orbital mechanics and high-fidelity sensor error models and provide a solution with increased accuracy and robustness relative to any single relative navigation sensor. The filters were tested tinough stand-alone covariance analysis, closed-loop testing with a high-fidelity multi-body orbital simulation, and hardware-in-the-loop (HWIL) testing in the Marshall Space Flight Center (MSFC) Flight Robotics Laboratory (FRL).

  1. Orbit Modification of Earth-Crossing Asteroids/Comets Using Rendezvous Spacecraft and Laser Ablation

    NASA Technical Reports Server (NTRS)

    Park, Sang-Young; Mazanek, Daniel D.

    2005-01-01

    This report describes the approach and results of an end-to-end simulation to deflect a long-period comet (LPC) by using a rapid rendezvous spacecraft and laser ablation system. The laser energy required for providing sufficient deflection DELTA V and an analysis of possible intercept/rendezvous spacecraft trajectories are studied in this analysis. These problems minimize a weighted sum of the flight time and required propellant by using an advanced propulsion system. The optimal thrust-vector history and propellant mass to use are found in order to transfer a spacecraft from the Earth to a targeted celestial object. One goal of this analysis is to formulate an optimization problem for intercept/rendezvous spacecraft trajectories. One approach to alter the trajectory of the object in a highly controlled manner is to use pulsed laser ablative propulsion. A sufficiently intense laser pulse ablates the surface of a near-Earth object (NEO) by causing plasma blowoff. The momentum change from a single laser pulse is very small. However, the cumulative effect is very effective because the laser can interact with the object over long periods of time. The laser ablation technique can overcome the mass penalties associated with other nondisruptive approaches because no propellant is required to generate the DELTA V (the material of the celestial object is the propellant source). Additionally, laser ablation is effective against a wide range of surface materials and does not require any landing or physical attachment to the object. For diverting distant asteroids and comets, the power and optical requirements of a laser ablation system on or near the Earth may be too extreme to contemplate in the next few decades. A hybrid solution would be for a spacecraft to carry a laser as a payload to a particular celestial body. The spacecraft would require an advanced propulsion system capable of rapid rendezvous with the object and an extremely powerful electrical generator, which is likely needed for the propulsion system as well. The spacecraft would station-keep with the object at a small standoff distance while the laser ablation is performed.

  2. Predicting performance in manually controlled rendezvous and docking through spatial abilities

    NASA Astrophysics Data System (ADS)

    Wang, Chunhui; Tian, Yu; Chen, Shanguang; Tian, Zhiqiang; Jiang, Ting; Du, Feng

    2014-01-01

    Manually controlled rendezvous and docking (manual RVD) is a challenging space task for astronauts. This study aims to identify spatial abilities that are critical for accomplishing manual RVD. Based on task analysis, spatial abilities were deduced to be critical for accomplishing manual RVD. 15 Male participants performed manual RVD task simulations and spatial ability tests (the object-manipulation spatial ability and spatial orientation ability). Participants' performance in the test of visualization of viewpoints (which measures the spatial orientation ability) was found to be significantly correlated with their manual RVD performance, indicating that the spatial orientation ability in the sense of perspective taking is particularly important for accomplishing manual RVD.

  3. Proximity Operations Nano-Satellite Flight Demonstration (PONSFD) Rendezvous Proximity Operations Design and Trade Studies

    NASA Astrophysics Data System (ADS)

    Griesbach, J.; Westphal, J. J.; Roscoe, C.; Hawes, D. R.; Carrico, J. P.

    2013-09-01

    The Proximity Operations Nano-Satellite Flight Demonstration (PONSFD) program is to demonstrate rendezvous proximity operations (RPO), formation flying, and docking with a pair of 3U CubeSats. The program is sponsored by NASA Ames via the Office of the Chief Technologist (OCT) in support of its Small Spacecraft Technology Program (SSTP). The goal of the mission is to demonstrate complex RPO and docking operations with a pair of low-cost 3U CubeSat satellites using passive navigation sensors. The program encompasses the entire system evolution including system design, acquisition, satellite construction, launch, mission operations, and final disposal. The satellite is scheduled for launch in Fall 2015 with a 1-year mission lifetime. This paper provides a brief mission overview but will then focus on the current design and driving trade study results for the RPO mission specific processor and relevant ground software. The current design involves multiple on-board processors, each specifically tasked with providing mission critical capabilities. These capabilities range from attitude determination and control to image processing. The RPO system processor is responsible for absolute and relative navigation, maneuver planning, attitude commanding, and abort monitoring for mission safety. A low power processor running a Linux operating system has been selected for implementation. Navigation is one of the RPO processor's key tasks. This entails processing data obtained from the on-board GPS unit as well as the on-board imaging sensors. To do this, Kalman filters will be hosted on the processor to ingest and process measurements for maintenance of position and velocity estimates with associated uncertainties. While each satellite carries a GPS unit, it will be used sparsely to conserve power. As such, absolute navigation will mainly consist of propagating past known states, and relative navigation will be considered to be of greater importance. For relative observations, each spacecraft hosts 3 electro-optical sensors dedicated to imaging the companion satellite. The image processor will analyze the images to obtain estimates for range, bearing, and pose, with associated rates and uncertainties. These observations will be fed to the RPO processor's relative Kalman filter to perform relative navigation updates. This paper includes estimates for expected navigation accuracies for both absolute and relative position and velocity. Another key task for the RPO processor is maneuver planning. This includes automation to plan maneuvers to achieve a desired formation configuration or trajectory (including docking), as well as automation to safely react to potentially dangerous situations. This will allow each spacecraft to autonomously plan fuel-efficient maneuvers to achieve a desired trajectory as well as compute adjustment maneuvers to correct for thrusting errors. This paper discusses results from a trade study that has been conducted to examine maneuver targeting algorithms required on-board the spacecraft. Ground software will also work in conjunction with the on-board software to validate and approve maneuvers as necessary.

  4. An overview of autonomous rendezvous and docking system technology development

    NASA Astrophysics Data System (ADS)

    Nelson, Kurt D.

    The Centaur upper stage was selected for an airborne avionics modernization program. The parts used in the existing avionics units were obsolete. Continued use of existing hardware would require substantial redesign, yet would result in the use of outdated hardware. Out of date processes, with very expensive and labor intensive technologies, were being used for manufacturing. The Atlas/Centaur avionics were to be procured at a fairly high rate that demanded the use of modern components. The new avionics also reduce size, weight, power, and parts count with a dramatic improvement in reliability. Finally, the cost leverage derived from upgrading the avionics as opposed to any other subsystem for the existing Atlas/Centaur was a very large consideration in the upgrade decision. The upgrade program is a multiyear effort that began in 1989. It includes telemetry, guidance and navigation, control electronics, thrust vector control, and redundancy levels.

  5. Space Shuttle Program: Automatic rendezvous, proximity operations, and capture (category 3)

    NASA Astrophysics Data System (ADS)

    Jackson, William L.; Lee, Roscoe; Eick, Richard E.; Hallstrom, J. V.; Hiers, Harry K.; McManamen, John P.; Olszewski, Oscar W.; Prather, Joseph L.; Rue, D. L.; Zimmer, Karl J.

    The NASA Johnson Space Center is actively pursuing the development and demonstration of capabilities for automatic rendezvous, proximity operations, and capture (AR&C) using the Space Shuttle as the active vehicle. This activity combines the technologies, expertise, tools, and facilities of the JSC Tracking and Communications Division (EE), Navigation, Control and Aeronautics Division (EG), Automation and Robotics Division (ER), and Structures and Mechanics Division (ES) of the Engineering Directorate and the Flight Design and Dynamics Division (DM) of the Mission Operations Directorate. Potential benefits of AR&C include more efficient and repeatable rendezvous, proximity operations, and capture operations; reduced impacts on the target vehicles (e.g., Orbiter RCS plume loads); reduced flight crew work loads; reduced ground support requirements; and reduced operational constraints. This paper documents the current JSC capabilities/tools/facilities for AR&C and describes a proposed plan for a progression of ground demonstrations and flight tests and demonstrations of AR&C capabilities. This plan involves the maturing of existing technologies in tracking and communications; guidance, navigation and control; mechanisms; manipulators; and systems management and integrating them into several evolutionary demonstration stages.

  6. Guidance Algorithms for the Near-Distance Rendezvous of On-Orbit-Servicing Spacecraft

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Cao, Xibin; Chen, Xueqin

    This paper presents algorithms for the near-distance rendezvous of on-orbit-servicing spacecraft when approaching, departing and flying around a target vehicle in a circular orbit. These algorithms are based on the closed-form solution of linear Clohessy-Wiltshire equations and adapt the glideslope guidance used in the past for rendezvous and proximity operations of the space shuttle. By using the relationship of either power functions or piece linear functions between distance and speed, the multipulse glideslope approach and departure algorithms of the chaser can be applied at any time and in any direction in space for decelerating when approaching a target or a nearby location and accelerating when departing. The fly-around algorithm enables the chaser to circumnavigate a target in any plane and at any specified time. To save the pulse number for all algorithms, a way to solve the maximum allowable transfer interval between one pulse and the next one is presented, with consideration be given to the constraints about allowable safe velocity and allowable guidance error. Finally, several scenarios are simulated to illustrate these guidance algorithms.

  7. Orbital Express Autonomous Rendezvous and Capture Sensor System (ARCSS) flight test results

    NASA Astrophysics Data System (ADS)

    Leinz, Manny R.; Chen, Chih-Tsai; Beaven, Michael W.; Weismuller, Thomas P.; Caballero, David L.; Gaumer, William B.; Sabasteanski, Peter W.; Scott, Peter A.; Lundgren, Mark A.

    2008-04-01

    The Orbital Express flight demonstration was established by the Defense Advanced Research Projects Agency (DARPA) to develop and validate key technologies required for cost-effective servicing of next-generation satellites. A contractor team led by Boeing Advanced Network and Space Systems built two mated spacecraft launched atop an Atlas V rocket from Cape Canaveral, Florida, on March 8, 2007. The low earth orbit test flight demonstrated on orbit transfer of hydrazine propellant, transfer of a spare battery between spacecraft and the ability to replace a spacecraft computer on orbit. It also demonstrated autonomous rendezvous and capture (AR&C) using advanced sensor, guidance, and relative navigation hardware and software. This paper summarizes the results of the on-orbit performance testing of the ARCSS (Autonomous Rendezvous and Capture Sensor System). ARCSS uses onboard visible, infrared and laser rangefinder sensors to provide real time data and imagery to the onboard sensor computer. The Boeing-developed Vis-STAR software executing on the sensor computer uses the ARCSS data to provide precision real-time client bearing, range and attitude as needed, from long range to soft capture. The paper summarizes the ARCSS and Vis-STAR on orbit performance.

  8. Use of industrial robots for hardware-in-the-loop simulation of satellite rendezvous and docking

    NASA Astrophysics Data System (ADS)

    Ma, Ou; Flores-Abad, Angel; Boge, Toralf

    2012-12-01

    One of the most challenging and risky operations for spacecraft is to perform rendezvous and docking autonomously in space. To ensure a safe and reliable operation, such a mission must be carefully designed and thoroughly verified before a real space mission can be launched. This paper describes the control strategy for achieving high fidelity contact dynamics simulation of a new, robotics-based, hardware-in-the-loop (HIL) rendezvous and docking simulation facility that uses two industrial robots to physically simulate the 6-DOF dynamic maneuvering of two docking satellites. The facility is capable of physically simulating the final approaching within a 25-meter range and the entire docking/capturing process for a satellite on-orbit servicing mission. The key difficulties of using industrial robots for high-fidelity HIL contact dynamics simulation were found and different solution techniques were investigated in the presented project. An admittance control method was proposed to achieve the goal of making the robots in the HIL simulation process match the impedance of the two docking satellites. Simulation study showed the effectiveness and performance of the proposed solution method.

  9. Space Shuttle Guidance, Navigation, and Rendezvous Knowledge Capture Reports. Revision 1

    NASA Technical Reports Server (NTRS)

    Goodman, John L.

    2011-01-01

    This document is a catalog and readers guide to lessons learned, experience, and technical history reports, as well as compilation volumes prepared by United Space Alliance personnel for the NASA/Johnson Space Center (JSC) Flight Dynamics Division.1 It is intended to make it easier for future generations of engineers to locate knowledge capture documentation from the Shuttle Program. The first chapter covers observations on documentation quality and research challenges encountered during the Space Shuttle and Orion programs. The second chapter covers the knowledge capture approach used to create many of the reports covered in this document. These chapters are intended to provide future flight programs with insight that could be used to formulate knowledge capture and management strategies. The following chapters contain descriptions of each knowledge capture report. The majority of the reports concern the Space Shuttle. Three are included that were written in support of the Orion Program. Most of the reports were written from the years 2001 to 2011. Lessons learned reports concern primarily the shuttle Global Positioning System (GPS) upgrade and the knowledge capture process. Experience reports on navigation and rendezvous provide examples of how challenges were overcome and how best practices were identified and applied. Some reports are of a more technical history nature covering navigation and rendezvous. They provide an overview of mission activities and the evolution of operations concepts and trajectory design. The lessons learned, experience, and history reports would be considered secondary sources by historians and archivists.

  10. A Comparison of Trajectory Optimization Methods for the Impulsive Minimum Fuel Rendezvous Problem

    NASA Technical Reports Server (NTRS)

    Hughes, Steven P.; Mailhe, Laurie M.; Guzman, Jose J.

    2003-01-01

    In this paper we present, a comparison of trajectory optimization approaches for the minimum fuel rendezvous problem. Both indirect and direct methods are compared for a variety of test cases. The indirect approach is based on primer vector theory. The direct approaches are implemented numerically and include Sequential Quadratic Programming (SQP). Quasi- Newton and Nelder-Meade Simplex. Several cost function parameterizations are considered for the direct approach. We choose one direct approach that appears to be the most flexible. Both the direct and indirect methods are applied to a variety of test cases which are chosen to demonstrate the performance of each method in different flight regimes. The first test case is a simple circular-to-circular coplanar rendezvous. The second test case is an elliptic-to-elliptic line of apsides rotation. The final test case is an orbit phasing maneuver sequence in a highly elliptic orbit. For each test case we present a comparison of the performance of all methods we consider in this paper.

  11. Space Shuttle Program: Automatic rendezvous, proximity operations, and capture (category 3)

    NASA Technical Reports Server (NTRS)

    Jackson, William L.; Lee, Roscoe; Eick, Richard E.; Hallstrom, J. V.; Hiers, Harry K.; Mcmanamen, John P.; Olszewski, Oscar W.; Prather, Joseph L.; Rue, D. L.; Zimmer, Karl J.

    1991-01-01

    The NASA Johnson Space Center is actively pursuing the development and demonstration of capabilities for automatic rendezvous, proximity operations, and capture (AR&C) using the Space Shuttle as the active vehicle. This activity combines the technologies, expertise, tools, and facilities of the JSC Tracking and Communications Division (EE), Navigation, Control and Aeronautics Division (EG), Automation and Robotics Division (ER), and Structures and Mechanics Division (ES) of the Engineering Directorate and the Flight Design and Dynamics Division (DM) of the Mission Operations Directorate. Potential benefits of AR&C include more efficient and repeatable rendezvous, proximity operations, and capture operations; reduced impacts on the target vehicles (e.g., Orbiter RCS plume loads); reduced flight crew work loads; reduced ground support requirements; and reduced operational constraints. This paper documents the current JSC capabilities/tools/facilities for AR&C and describes a proposed plan for a progression of ground demonstrations and flight tests and demonstrations of AR&C capabilities. This plan involves the maturing of existing technologies in tracking and communications; guidance, navigation and control; mechanisms; manipulators; and systems management and integrating them into several evolutionary demonstration stages.

  12. An integrated autonomous rendezvous and docking system architecture using Centaur modern avionics

    NASA Technical Reports Server (NTRS)

    Nelson, Kurt

    1991-01-01

    The avionics system for the Centaur upper stage is in the process of being modernized with the current state-of-the-art in strapdown inertial guidance equipment. This equipment includes an integrated flight control processor with a ring laser gyro based inertial guidance system. This inertial navigation unit (INU) uses two MIL-STD-1750A processors and communicates over the MIL-STD-1553B data bus. Commands are translated into load activation through a Remote Control Unit (RCU) which incorporates the use of solid state relays. Also, a programmable data acquisition system replaces separate multiplexer and signal conditioning units. This modern avionics suite is currently being enhanced through independent research and development programs to provide autonomous rendezvous and docking capability using advanced cruise missile image processing technology and integrated GPS navigational aids. A system concept was developed to combine these technologies in order to achieve a fully autonomous rendezvous, docking, and autoland capability. The current system architecture and the evolution of this architecture using advanced modular avionics concepts being pursued for the National Launch System are discussed.

  13. Endoscopic Sphincterotomy Using the Rendezvous Technique for Choledocholithiasis during Laparoscopic Cholecystectomy: A Case Report.

    PubMed

    Tanaka, Takayuki; Haraguchi, Masashi; Tokai, Hirotaka; Ito, Shinichiro; Kitajima, Masachika; Ohno, Tsuyoshi; Onizuka, Shinya; Inoue, Keiji; Motoyoshi, Yasuhide; Kuroki, Tamotsu; Kanemastu, Takashi; Eguchi, Susumu

    2014-05-01

    A 50-year-old male was examined at another hospital for fever, general fatigue and slight abdominal pain. He was treated with antibiotics and observed. However, his symptoms did not lessen, and laboratory tests revealed liver dysfunction, jaundice and an increased inflammatory response. He was then admitted to our hospital and underwent an abdominal computed tomography scan and magnetic resonance cholangiopancreatography (MRCP), which revealed common bile duct (CBD) stones. He was diagnosed with mild acute cholangitis. As the same time, he was admitted to our hospital and an emergency endoscopic retrograde cholangiopancreatography was performed. Vater papilla opening in the third portion of the duodenum and presence of a peripapillary duodenal diverticulum made it difficult to perform cannulation of the CBD. In addition, MRCP revealed that the CBD was extremely narrow (diameter 5 mm). We therefore performed laparoscopic cholecystectomy and endoscopic sphincterotomy using the rendezvous technique for choledocholithiasis simultaneously rather than laparoscopic CBD exploration. After the operation, the patient was discharged with no complications. Although the rendezvous technique has not been very commonly used because several experts in the technique and a large operating room are required, this technique is a very attractive and effective approach for treating choledocholithiasis, for which endoscopic treatment is difficult. PMID:25298761

  14. Autonomous rendezvous and docking operations of unmanned expendable cargo transfer vehicles (e.g. Centaur) with Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Emmet, Brian R.

    1991-01-01

    This paper describes the results of the feasibility study using Centaur or other CTV's to deliver payloads to the Space Station Freedom (SSF). During this study was examined the requirements upon unmanned cargo transfer stages (including Centaur) for phasing, rendezvous, proximity operations and docking/berthing (capture).

  15. The Successful Development of an Automated Rendezvous and Capture (AR&C) System for the National Aeronautics and Space Administration

    NASA Technical Reports Server (NTRS)

    Roe, Fred D.; Howard, Richard T.

    2003-01-01

    During the 1990's, the Marshall Space Flight Center (MSFC) conducted pioneering research in the development of an automated rendezvous and capture/docking (AR&C) system for U.S. space vehicles. Development and demonstration of a rendezvous sensor was identified early in the AR&C Program as the critical enabling technology that allows automated proximity operations and docking. A first generation rendezvous sensor, the Video Guidance Sensor (VGS), was developed and successfully flown on STS-87 and STS-95, proving the concept of a video- based sensor. A ground demonstration of the entire system and software was successfully tested. Advances in both video and signal processing technologies and the lessons learned from the two successful flight experiments provided a baseline for the development, by the MSFC, of a new generation of video based rendezvous sensor. The Advanced Video Guidance Sensor (AGS) has greatly increased performance and additional capability for longer-range operation with a new target designed as a direct replacement for existing ISS hemispherical reflectors.

  16. Precise Attitude Determination for RendezVous and Docking by Information Fusion of Laser Range Finder Measurements

    Microsoft Academic Search

    Roland Strietzel

    2002-01-01

    For the docking of spacecrafts a highly precise attitude and position control is necessary. This requires an adequate measurement of the relative position and attitude of the docking spacecrafts. Here is presented, how a rendezvous and docking sensor (RVS) consisting of a laser range finder (LRF) with a scanning mirror system and a set of retro reflectors can be used

  17. Active rendezvous between a low-earth orbit user spacecraft and the Space Transportation System (STS) shuttle

    NASA Technical Reports Server (NTRS)

    Hooper, H. L.; Herrnstein, J. R.

    1989-01-01

    Active rendezvous of an unmanned spacecraft with the Space Transportation System (STS) Shuttle is considered. The various operational constraints facing both the maneuvering spacecraft and the Shuttle during such a rendezvous sequence are discussed. Specifically, the actively rendezvousing user spacecraft must arrive in the generic Shuttle control box at a specified time after Shuttle launch. In so doing it must at no point violate Shuttle separation requirements. In addition, the spacecraft must be able to initiate the transfer sequence from any point in its orbit. The four-burn rendezvous sequence incorporating two Hohmann transfers and an intermediate phasing orbit as a low-energy solution satisfying the above requirements are discussed. The general characteristics of the four-burn sequence are discussed, with emphasis placed on phase orbit altitude and delta-velocity requirements. The planning and execution of such a sequence in the operational environment are then considered. Factor crucial in maintaining the safety of both spacecraft, such as spacecraft separation and contingency analysis, are considered in detail.

  18. Monde arabe : des rvolutions en trompe l'oeil Vers un nouveau rendez-vous manqu avec l'Occident ?

    E-print Network

    Paris-Sud XI, Université de

    1 Monde arabe : des révolutions en trompe l'oeil Vers un nouveau rendez-vous manqué avec l'Occident ? De prime abord, il paraît aller de soi d'insérer un chapitre sur les « révolutions arabes » dans un advienne, celle des soulèvements populaires spontanés et inattendus d'un bout à l'autre du monde arabe

  19. A Summary of the Rendezvous, Proximity Operations, Docking, and Undocking (RPODU) Lessons Learned from the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) Demonstration System Mission

    NASA Technical Reports Server (NTRS)

    Dennehy, Cornelius J.; Carpenter, James R.

    2011-01-01

    The Guidance, Navigation, and Control (GN&C) Technical Discipline Team (TDT) sponsored Dr. J. Russell Carpenter, a Navigation and Rendezvous Subject Matter Expert (SME) from NASA's Goddard Space Flight Center (GSFC), to provide support to the Defense Advanced Research Project Agency (DARPA) Orbital Express (OE) rendezvous and docking flight test that was conducted in 2007. When that DARPA OE mission was completed, Mr. Neil Dennehy, NASA Technical Fellow for GN&C, requested Dr. Carpenter document his findings (lessons learned) and recommendations for future rendezvous missions resulting from his OE support experience. This report captures lessons specifically from anomalies that occurred during one of OE's unmated operations.

  20. Analysis of Tumble and Its Effects on EGR Tolerance for a Gasoline Engine Running at High Loads

    NASA Astrophysics Data System (ADS)

    Easter, Jordan; Puzinauskas, Paulius; Pyles, Timothy

    2012-11-01

    The series hybrid electric vehicle allows for the design of an engine that can run solely at its most efficient point, wide open throttle (WOT). However, at WOT there is an increase in emissions not typically handled in the conventional gasoline engine. Exhaust gas recirculation can be used to reduce emissions if the tolerance of the engine for the exhaust gas is increased. It is hypothesized that tolerance at WOT will increase when there is an increase in in-cylinder turbulence. In this research, aluminum flow guide vanes were inserted in the intake to induce tumble. The flow was examined through the use of PIV techniques and the increase in EGR tolerance was verified with engine testing. PIV images of the flow structure were taken between the intake valves of a modified cylinder designed to mimic bottom dead center. The lift to valve diameters as well as the vane configurations were altered. Engine testing was performed with varying vane configurations, while the EGR percentage was increased until it became difficult to control combustion. It was been found through the engine testing that the flow guide vanes do significantly increase the EGR tolerance as well as combustion stability. Funding received by the NSF REU Grant 1062611.

  1. Mars Orbit Rendezvous Strategy for the Mars 2003/2005 Sample Return Mission

    NASA Technical Reports Server (NTRS)

    DAmario, Louis A.; Bollman, Willard E.; Lee, Wayne J.; Roncoli, Ralph B.; Smith, John C.

    1999-01-01

    The primary objective of the Mars 2003/2005 Sample Return Project is to return Martian surface materials to Earth from two different sites by the year 2008. The baseline mission plan relies heavily on the use of a Mars orbit rendezvous strategy similar to the lunar orbit rendezvous scheme used for the Apollo missions. The 2003 mission consists of a single spacecraft comprised of a Lander, Rover, and Mars ascent vehicle (MAV). The 2003 mission will be launched on a Delta-III-class launch vehicle in May/June 2003 and arrive at Mars in December 2003/January 2004. The Lander deploys the Rover to collect surface samples from several sites and return them to the Lander where they are transferred to a sample canister onboard the MAV. The MAV is launched into a low Mars orbit (targeted for 600 km circular, 45 deg inclination) and releases the sample canister to await retrieval by an Orbiter launched in 2005. (The sample canister is a passive vehicle with no maneuvering capability.) The duration of Mars surface operations is at most about 90 days. The 2005 mission consists of two separate spacecraft: a Lander/Rover/MAV spacecraft identical to that used for the 2003 mission and an Orbiter carrying an Earth Entry Vehicle (EEV). Both spacecraft will be launched on a single Ariane-5 in August 2005 and arrive at Mars in July/August 2006. A second sample canister is delivered to Mars orbit using the same scenario as was used for the 2003 mission. The Orbiter uses aerocapture for insertion into Mars orbit (targeted for 250 x 1400 km, 45 deg inclination). During its approximately one-year stay at Mars, the Orbiter will search for and attempt to rendezvous first with the 2003 sample canister and then with the 2005 sample canister. After retrieval, each sample canister is transferred to the EEV. The Orbiter departs Mars in July 2007 and returns to Earth in October 2008 on a trajectory targeted for landing at the Utah Test and Training Range (UTTR). After deploying the EEV, the Orbiter performs a deflection maneuver to avoid reentry into Earth's atmosphere.

  2. Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation

    NASA Technical Reports Server (NTRS)

    Tchoryk, Peter, Jr.; Whitten, Raymond P.

    1991-01-01

    SpARC, in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components wherever possible. The primary subsystems to be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be ELV based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. After the second COMET spacecraft has been launched in late 1994, the ARD demonstration will take place. The service module from the second COMET will serve as the chase vehicle.

  3. Report of the Task Force on the Shuttle-Mir Rendezvous and Docking Missions

    NASA Technical Reports Server (NTRS)

    1994-01-01

    In October 1992, Russia and the U.S. agreed to conduct a fundamentally new program of human cooperation in space. This original 'Shuttle-Mir' project encompassed combined astronaut-cosmonaut activities on the Shuttle, Soyuz, and Mir spacecraft. At that time, the project was limited to: the STS-60 Shuttle mission, which was completed in February 1994 and carried the first Russian cosmonaut; the planned March 1995 Soyuz 18 launch which will carry a U.S. astronaut to the Mir space station for a three month mission; and the STS-71 Shuttle mission which is scheduled to rendezvous and dock with the Mir space station in June 1995. The Task Force's specific recommendations are given.

  4. Solar array study for solar electric propulsion spacecraft for the Encke rendezvous mission

    NASA Technical Reports Server (NTRS)

    Sequeira, E. A.; Patterson, R. E.

    1974-01-01

    The work is described which was performed on the design, analysis and performance of a 20 kW rollup solar array capable of meeting the design requirements of a solar electric spacecraft for the 1980 Encke rendezvous mission. To meet the high power requirements of the proposed electric propulsion mission, solar arrays on the order of 186.6 sq m were defined. Because of the large weights involved with arrays of this size, consideration of array configurations is limited to lightweight, large area concepts with maximum power-to-weight ratios. Items covered include solar array requirements and constraints, array concept selection and rationale, structural and electrical design considerations, and reliability considerations.

  5. Rendezvous strategy impacts on CTV avionics design, system reliability requirements, and available collision avoidance maneuvers

    NASA Technical Reports Server (NTRS)

    Donovan, William J.; Davis, John E.

    1991-01-01

    Rockwell International is conducting an ongoing program to develop avionics architectures that provide high intrinsic value while meeting all mission objectives. Studies are being conducted to determine alternative configurations that have low life-cycle cost and minimum development risk, and that minimize launch delays while providing the reliability level to assure a successful mission. This effort is based on four decades of providing ballistic missile avionics to the United States Air Force and has focused on the requirements of the NASA Cargo Transfer Vehicle (CTV) program in 1991. During the development of architectural concepts it became apparent that rendezvous strategy issues have an impact on the architecture of the avionics system. This is in addition to the expected impact on propulsion and electrical power duration, flight profiles, and trajectory during approach.

  6. Wookie Rendezvous 

    E-print Network

    Multiple Contributors

    1999-01-01

    pocket. She had just leaned back against her pillows when Solo woke, stretched and yawned. "Hi, Your Worship!" he said, pleasure shining in his hazel eyes as he found her awake and sitting up. "How ya feelin'? With such a handsome doctor I know you...

  7. Near Earth Asteroid Rendezvous (NEAR) Revised Eros Orbit Phase Trajectory Design

    NASA Technical Reports Server (NTRS)

    Helfrich, J; Miller, J. K.; Antreasian, P. G.; Carranza, E.; Williams, B. G.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

    1999-01-01

    Trajectory design of the orbit phase of the NEAR mission involves a new process that departs significantly from those procedures used in previous missions. In most cases, a precise spacecraft ephemeris is designed well in advance of arrival at the target body. For NEAR, the uncertainty in the dynamic environment around Eros does not allow the luxury of a precise spacecraft trajectory to be defined in advance. The principal cause of this uncertainty is the limited knowledge oi' the gravity field a,-id rotational state of Eros. As a result, the concept for the NEAR trajectory design is to define a number of rules for satisfying spacecraft, mission, and science constraints, and then apply these rules to various assumptions for the model of Eros. Nominal, high, and low Eros mass models are used for testing the trajectory design strategy and to bracket the ranges of parameter variations that are expected upon arrival at the asteroid. The final design is completed after arrival at Eros and determination of the actual gravity field and rotational state. As a result of the unplanned termination of the deep space rendezvous maneuver on December 20, 1998, the NEAR spacecraft passed within 3830 km of Eros on December 23, 1998. This flyby provided a brief glimpse of Eros, and allowed for a more accurate model of the rotational parameters and gravity field uncertainty. Furthermore, after the termination of the deep space rendezvous burn, contact with the spacecraft was lost and the NEAR spacecraft lost attitude control. During the subsequent gyrations of the spacecraft, hydrazine thruster firings were used to regain attitude control. This unplanned thruster activity used Much of the fuel margin allocated for the orbit phase. Consequently, minimizing fuel consumption is now even more important.

  8. A family of low-cost transfer orbits for rendezvous-type missions to NEAs

    NASA Astrophysics Data System (ADS)

    Berinde, Stefan

    2007-05-01

    Low-cost rendezvous missions to near-Earth asteroids (NEAs) are likely to be designed more often in the future, both for scientific exploration and also for impact hazard mitigation. Ballistic orbits are usually highly expensive in terms of energy budget. More sophisticated gravity assisted orbits involve strong phasing requirements between Earth, flyby planets and asteroid. Only few targets are accessible in this manner. In this paper we develop a family of, general purpose, transfer trajectories (called resonant Earth-flyby trajectories) suitable for the peculiarity of NEAs orbits (having at least one orbital node near Earth's orbit). Such a transfer orbit involves one or more deep-space maneuvers (DSMs) and several resonant flyby returns with the Earth. The idea is to build, at first, a large enough relative velocity in respect to the Earth using these DSMs applied near aphelion. Next, successive rotations of this relative velocity vector due to flybys on resonant orbits will, finally, shape the orbit of the spacecraft in order to match the inclination of the asteroid's orbit and, also, the orientation of its apsidal line. Much is done by Earth flybys, without other energy consumptions. On the acquired orbit the spacecraft needs a much smaller velocity impulse to perform the rendezvous. This technique is applicable to most of the NEAs discovered so far, the difference being in phasing requirements and in the total transfer time. The total energy budget will be much smaller compared with the energy budget on free ballistic trajectories. The range of applicability is discussed and near future opportunities are outlined. The theory is developed in the frame of Opik's geometric formalism (two-body orbital transfer), which enable us to track the problem analytically as much as possible.

  9. Multiple spacecraft rendezvous maneuvers by differential drag and low thrust engines

    NASA Astrophysics Data System (ADS)

    Bevilacqua, Riccardo; Hall, Jason S.; Romano, Marcello

    2010-01-01

    A novel two-phase hybrid controller is proposed to optimize propellant consumption during multiple spacecraft rendezvous maneuvers in Low Earth Orbit. This controller exploits generated differentials in aerodynamic drag on each involved chaser spacecraft to effect a propellant-free trajectory near to the target spacecraft during the first phase of the maneuver, and then uses a fuel optimal control strategy via continuous low-thrust engines to effect a precision dock during the second phase. In particular, by varying the imparted aerodynamic drag force on each of the chaser spacecraft, relative differential accelerations are generated between each chaser and the target spacecraft along two of the three translational degrees of freedom. In order to generate this required differential, each chaser spacecraft is assumed to include a system of rotating flat panels. Additionally, each chaser spacecraft is assumed to have continuous low-thrust capability along the three translational degrees of freedom and full-axis attitude control. Sample simulations are presented to support the validity and robustness of the proposed hybrid controller to variations in the atmospheric density along with different spacecraft masses and ballistic coefficients. Furthermore, the proposed hybrid controller is validated against a complete nonlinear orbital model to include relative navigation errors typical of carrier-phase differential GPS (CDGPS). Limitations of the proposed controller appear relative to the target spacecraft's orbit eccentricity and a general characterization of the atmospheric density. Bounds on these variables are included to provide a framework within which the proposed hybrid controller can effect an extremely low propellant rendezvous of multiple chaser spacecraft to a desired target spacecraft.

  10. Evaluation of GPS position and attitude determination for automated rendezvous and docking missions. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Diprinzio, Marc D.; Tolson, Robert H.

    1994-01-01

    The use of the Global Positioning System for position and attitude determination is evaluated for an automated rendezvous and docking mission. The typical mission scenario involves the chaser docking with the target for resupply or repair purposes, and is divided into three sections. During the homing phase, the chaser utilizes coarse acquisition pseudorange data to approach the target; guidance laws for this stage are investigated. In the second phase, differential carrier phase positioning is utilized. The chaser must maintain a quasiconstant distance from the target, in order to resolve the initial integer ambiguities. Once the ambiguities are determined, the terminal phase is entered, and the rendezvous is completed with continuous carrier phase tracking. Attitude knowledge is maintained in all phases through the use of the carrier phase observable. A Kalman filter is utilized to estimate all states from the noisy measurement data. The effects of selective availability and cycle slips are also investigated.

  11. Rendezvous of Glowworm-Inspired Robot Swarms at Multiple Source Locations: A Sound Source Based Real-Robot Implementation

    Microsoft Academic Search

    Krishnanand N. Kaipa; Amruth Puttappa; Guruprasad M. Hegde; Sharschchandra V. Bidargaddi; Debasish Ghose

    2006-01-01

    This paper presents a novel glowworm metaphor based distributed algorithm that enables a minimalist mobile robot swarm to\\u000a effectively split into subgroups, exhibit simultaneous taxis towards, and rendezvous at multiple source locations. The locations\\u000a of interest could represent radiation sources such as nuclear and hazardous aerosol spills spread within an unknown environment.\\u000a The glowworm algorithm is based on a glowworm

  12. Rendezvous Regions: A Scalable Architecture for Self-Configuration and Data-Centric Storage in Sensor Networks

    Microsoft Academic Search

    Karim Seada; Ahmed Helmy

    Sensor networks are large-scale, self-organizing, distributed networks of small sensing devices embedded in the physical world. Due to the limited resources of the devices and the uncertainty of the environment, efficient and robust data-access mechanisms are both essential and challenging. Rendezvous-based data-access mechanisms provide an efficient and valuable solution for provisioning a wide range of services. In this paper, we

  13. Effects of beef enhancement with non-meat ingredients, blade tenderization, and vacuum tumbling on quality attributes of four beef cuts stored in a high oxygen environment

    E-print Network

    Williams, Tracey Ann

    2005-02-17

    (injected or non-injected), blade tenderization (0, 1, or 2 passes) and vacuum-tumbling (0, 5, 10 or 20 minutes). Injected muscles contained up to 10% of a brine containing 1.55% potassium lactate, 0.1% sodium diacetate, 0.3% sodium tripolyphosphate... evaluated steaks on day 1 only. Warner-Bratzler shear force (P<0.01) and trained sensory panel results (P<0.05) showed that the addition of non-meat ingredients improved tenderness in all four muscles. Sensory detectable connective tissue was lower (P<0...

  14. Radio science results during the NEAR-shoemaker spacecraft rendezvous with eros

    PubMed

    Yeomans; Antreasian; Barriot; Chesley; Dunham; Farquhar; Giorgini; Helfrich; Konopliv; McAdams; Miller; Owen; Scheeres; Thomas; Veverka; Williams

    2000-09-22

    We determined the mass of asteroid 433 Eros, its lower order gravitational harmonics, and rotation state, using ground-based Doppler and range tracking of the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft and images of the asteroid's surface landmarks. The mass of Eros is (6.687 +/- 0.003) x 10(18) grams, which, coupled with our volume estimate, implies a bulk density of 2. 67 +/- 0.03 grams per cubic centimeter. The asteroid appears to have a uniform density distribution. The right ascension and declination of the rotation pole are 11.37 +/- 0.05 and 17.22 +/- 0.05 degrees, respectively, and at least over the short term, the rotation state of Eros is stable with no measurable free precession of the spin pole. Escape velocities on the surface vary from 3.1 to 17.2 meters per second. The dynamical environment of Eros suggests that it is covered with regolith and that one might expect material transport toward the deepest potential wells in the saddle and 5.5-kilometer crater regions. PMID:11000104

  15. Autonomous rendezvous and docking: A commercial approach to on-orbit technology validation

    NASA Technical Reports Server (NTRS)

    Tchoryk, Peter, Jr.; Dobbs, Michael E.; Conrad, David J.; Apley, Dale J.; Whitten, Raymond P.

    1991-01-01

    The Space Automation and Robotics Center (SpARC), a NASA-sponsored Center for the Commercial Development of Space (CCDS), in conjunction with its corporate affiliates, is planning an on-orbit validation of autonomous rendezvous and docking (ARD) technology. The emphasis in this program is to utilize existing technology and commercially available components whenever possible. The primary subsystems that will be validated by this demonstration include GPS receivers for navigation, a video-based sensor for proximity operations, a fluid connector mechanism to demonstrate fluid resupply capability, and a compliant, single-point docking mechanism. The focus for this initial experiment will be expendable launch vehicle (ELV) based and will make use of two residual Commercial Experiment Transporter (COMET) service modules. The first COMET spacecraft will be launched in late 1992 and will serve as the target vehicle. The ARD demonstration will take place in late 1994, after the second COMET spacecraft has been launched. The service module from the second COMET will serve as the chase vehicle.

  16. Three-dimensional location and attitude evaluation for rendezvous and docking operation using a single camera

    NASA Astrophysics Data System (ADS)

    Wang, Zhiling; Losito, S.; Mugnuolo, Raffaele; Pasquariello, Guido

    1993-01-01

    In the automatic rendezvous and docking manoeuvre (RVD) of space activity, determining the 3-D location and attitude between two vehicles is most important. A vision system to perform the docking manipulation in RVD is described in this paper. An improved algorithm is used for calibrating the geometric parameters of a camera fixed on the tracking vehicle off-line. Because the line-off-sight angles of four markers on the target vehicle to the lens center of the camera can be computed according to the optical principle and vector theory, the locations of the vehicle are obtained from the solution for a set of nonlinear equations from the triangular theory. The attitude angles for the vehicles are solved by a translational matrix of target frame to vehicle frame. As the vehicle closes in to the target, sets of markers having different distance intervals or a list of calibration parameters for cameras with different fields of view are selected at the proper moment to improve the situation when at least one of the markers exceeds the field of camera view. The series of experiments is given. The vision system is run on a SUN-4/330 Sparc station system equipped with one image board IT-151 and a CCD TV camera. All software is written in C language.

  17. Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

    NASA Technical Reports Server (NTRS)

    Bilbro, James A.

    1991-01-01

    The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at ranges that are limited by the detection capability rather than by the signal-to-noise ratio (SNR) requirements. The sensor can provide translational state information (range, velocity, and angle) by direct measurement and, when used with any array detector, also can provide attitude information by Doppler imaging techniques. Identification of the target is accomplished by scanning with a high pulse repetition frequency (dependent on the SNR). The system performance is independent of range and should not be constrained by sun angle. An initial effort to characterize a multi-element detection system has resulted in a system that is expected to work to a minimum range of 1 meter. The system size, weight and power requirements are dependent on the operating range; 10 km range requires a diameter of 3 centimeters with overall size at 3 x 3 x 15 to 30 cm, while 100 km range requires a 30 cm diameter.

  18. Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

    NASA Astrophysics Data System (ADS)

    Bilbro, James A.

    The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at ranges that are limited by the detection capability rather than by the signal-to-noise ratio (SNR) requirements. The sensor can provide translational state information (range, velocity, and angle) by direct measurement and, when used with any array detector, also can provide attitude information by Doppler imaging techniques. Identification of the target is accomplished by scanning with a high pulse repetition frequency (dependent on the SNR). The system performance is independent of range and should not be constrained by sun angle. An initial effort to characterize a multi-element detection system has resulted in a system that is expected to work to a minimum range of 1 meter. The system size, weight and power requirements are dependent on the operating range; 10 km range requires a diameter of 3 centimeters with overall size at 3 x 3 x 15 to 30 cm, while 100 km range requires a 30 cm diameter.

  19. Laser radar instrument for the Near-Earth Asteroid Rendezvous (NEAR) mission

    NASA Astrophysics Data System (ADS)

    Cole, Timothy D.; Boies, Mark T.; El-Dinary, Ashruf S.

    1996-06-01

    In 1999 after a 3-year transit, the Near-Earth Asteroid Rendezvous (NEAR) spacecraft will enter a low-altitude (approximately 50 km) orbit about the asteroid, 433 Eros. Five instruments, including a laser radar, will operate continuously during the one-year orbit at Eros. The NEAR laser rangefinder (NLR), developed at the Applied Physics Laboratory (APL), is a robust rangefinder and the first spaceborne altimeter to have continuous inflight calibration capability. A bistatic configuration, the NLR uses a diode- pumped Cr:Nd:YAG transmitter and a leading-edge receiver with a 3.5-inch aperture Dall-Kirkham telescope. Detection is accomplished using an enhanced-silicon avalanche photodiode. From system tests, the NLR is capable of ranging in excess of 100 km to the asteroid's surface. Measurements of the time-of-flight between laser pulse firings and detection of surface backscatter are made using an APL- developed receiver having range resolution of 31.48 cm and accuracy of 2 m. Total mass of the NLR is 4.9 kg and its average power consumption is

  20. Autonomous reconfigurable GPS/INS navigation and pointing system for rendezvous and docking

    NASA Technical Reports Server (NTRS)

    Upadhyay, Triveni M.

    1991-01-01

    The briefing describes work using the Global Positioning System to determine position of spacecraft and the development of computer tools to utilize these position determinations to enable autonomous rendezvous. Using GPS data in conjunction with Inertial Navigation Systems (INS) provides the capability for absolute spacecraft navigation, navigation of one spacecraft relative to another, and attitude determination. Some results presented are based on limited observations, though simulation results are documented. A GPS/INS navigation flight experiment could provide a platform for evaluating approaches for autonomous operation and reconfigurability of the navigation and attitude determination subsystem for future space vehicles. Current emphasis is on the development and demonstration of an Onboard Mission Manager (OMM) and a Multi-Mode Navigation Kalman filter. Sensor data will be handed over to the OMM, which will determine the appropriate response and generate commands for the Kalman filter to use to reconfigure itself. Global Positioning System measurements and INS data will be processed in the integrated navigation filter and used to compute errors in position, velocity, and attitude. Inertial Navigation Systems instrument errors (biases, scale factors, etc.) also can be estimated. The OMM then will use a knowledge base to determine appropriate system response. The GPS is good for missions that have attitude pointing accuracy requirements within the 100 to 200 arcsecond range.

  1. An overview of autonomous rendezvous and docking system technology development at General Dynamics

    NASA Technical Reports Server (NTRS)

    Kuenzel, Fred

    1991-01-01

    The Centaur avionics suite is undergoing a dramatic modernization for the commercial, DoD Atlas and Titan programs. The system has been upgraded to the current state-of-the-art in ring laser gyro inertial sensors and Mil-Std-1750A processor technology. The Cruise Missile avionic system has similarly been evolving for many years. Integration of GPS into both systems has been underway for over five years with a follow-on cruise missile system currently in flight test. Rendezvous and Docking related studies have been conducted for over five years in support of OMV, CTV, and Advanced Upper Stages, as well as several other internal IR&D's. The avionics system and AR&D simulator demonstrated to the SATWG in November 1990 has been upgraded considerably under two IR&D programs in 1991. The Centaur modern avionics system is being flown in block upgrades which started in July of 1990. The Inertial Navigation Unit will fly in November of 1991. The Cruise Missile avionics systems have been fully tested and operationally validated in combat. The integrated AR&D system for space vehicle applications has been under development and testing since 1990. A Joint NASA / GD ARD&L System Test Program is currently being planned to validate several aspects of system performance in three different NASA test facilities in 1992.

  2. Tumbling in Space

    NSDL National Science Digital Library

    The Wisconsin Fast Plants Program

    The first activity in this newsletter was written to engage students in an investigation related to the Fast Plants that traveled into space in May of 1995. Students explore how plants use guidance systems which sense and respond to gravity (gravitropism) ensuring that roots anchor plants and access water and that shoots emerge into the light.This activity includes substantial background discussion about gravitropism in plants.

  3. Tumble Wing Walkalong Glider

    NSDL National Science Digital Library

    2012-07-12

    In this physics activity (page 2 of the PDF), learners will construct their own walkalong glider. They will explore how air, though invisible, surrounds and affects other objects. Learners will discover that air is made up of molecules that exert pressure on objects. Though this activity was created as a pre-visit for a traveling science show, it makes a great stand-alone activity as well.

  4. Electron Spin Relaxation Rates for Semiquinones between 25 and 295 K in Glass-Forming Solvents

    PubMed Central

    Kathirvelu, Velavan; Sato, Hideo; Eaton, Sandra S.; Eaton, Gareth R.

    2009-01-01

    Electron spin lattice relaxation rates for five semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,5-di-t-amyl-1,4-benzosemiquinone, 2,5-di-phenyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, tetrahydroxy-1,4-benzosemiquione) were studied by long-pulse saturation recovery EPR in 1:4 glycerol:ethanol, 1:1 glycerol:ethanol, and triethanolamine between 25 and 295 K. Although the dominant process changes with temperature, relaxation rates vary smoothly with temperature, even near the glass transition temperatures, and could be modeled as the sum of contributions that have the temperature dependence that is predicted for the direct, Raman, local mode and tumbling dependent processes. At 85 K, which is in a temperature range where the Raman process dominates, relaxation rates along the gxx (g~2.006) and gyy (g~2.005) axes are about 2.7 to 1.5 times faster than along the gzz axis (g = 2.0023). In highly viscous triethanolamine, contributions from tumbling-dependent processes are negligible. At temperatures above 100 K relaxation rates in triethanolamine are unchanged between X-band (9.5 GHz) and Q-band (34 GHz), so the process that dominates in this temperature interval was assigned as a local mode rather than a thermally-activated process. Because the largest proton hyperfine couplings are only 2.2 G, spin rotation makes a larger contribution than tumbling-dependent modulation of hyperfine anisotropy. Since g anisotropy is small, tumbling dependent modulation of g anisotropy make a smaller contribution than spin rotation at X-band. Although there was negligible impact of methyl rotation on T1, rotation of t-butyl or t-amyl methyl groups enhances spin echo dephasing between 85 and 150 K. PMID:19223213

  5. Fifth Report of the NASA Advisory Council Task Force on the Shuttle-Mir Rendezvous and Docking Missions

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The NASA Advisory Council Task Force on the Shuttle-Mir rendezvous and docking missions examine a number of specific issues related to the Shuttle-Mir program. Three teams composed of Task Force members and technical advisors were formed to address the follow issues: preliminary results from STS-71 and the status of preparations for STS-74; NASA's presence in Russia; and NASA's automated data processing and telecommunications (ADP/T) infrastructure in Russia. The three review team reports have been included in the fifth report of the Task Force.

  6. Infrared focal plane design for the Comet Rendezvous/Asteroid Flyby and Cassini Visible and Infrared Mapping Spectrometers

    NASA Technical Reports Server (NTRS)

    Staller, Craig; Niblack, Curtiss; Evans, Thomas; Blessinger, Michael; Westrick, Anthony

    1991-01-01

    A focal plane assembly combining hybrid electronic components with passive optical components within a single hermetically sealed package has been designed by Cincinnati Electronics to meet the performance requirements imposed by the Comet Rendezvous/Asteroid Flyby (CRAF) and Cassini Visible and Infrared Mapping Spectrometers (VIMSs). A single line array of 256 InSb photodiodes, accessed by two 1 x 128 multiplexers, provides continuous spectral coverage from 0.85 to 5.1 microns. Intrinsic field-of-view apertures and a unique order sorting filter require critical optical alignment within the hybrid. FPA performance requirements, design approach, and critical issues are discussed.

  7. Coherent Doppler lidar for automated space vehicle, rendezvous, station-keeping and capture

    NASA Technical Reports Server (NTRS)

    Dunkin, James A.

    1991-01-01

    Recent advances in eye-safe, short wavelength solid-state lasers offer real potential for the development of compact, reliable, light-weight, efficient coherent lidar. Laser diode pumping of these devices has been demonstrated, thereby eliminating the need for flash lamp pumping, which has been a major drawback to the use of these lasers in space based applications. Also these lasers now have the frequency stability required to make them useful in coherent lidar, which offers all of the advantages of non-coherent lidar, but with the additional advantage that direct determination of target velocity is possible by measurement of the Doppler shift. By combining the Doppler velocity measurement capability with the inherent high angular resolution and range accuracy of lidar it is possible to construct Doppler images of targets for target motion assessment. A coherent lidar based on a Tm,Ho:YAG 2-micrometer wavelength laser was constructed and successfully field tested on atmospheric targets in 1990. This lidar incorporated an all solid state (laser diode pumped) master oscillator, in conjunction with a flash lamp pumped slave oscillator. Solid-state laser technology is rapidly advancing, and with the advent of high efficiency, high power, semiconductor laser diodes as pump sources, all-solid-state, coherent lidars are a real possibility in the near future. MSFC currently has a feasibility demonstration effort under way which will involve component testing, and preliminary design of an all-solid-state, coherent lidar for automatic rendezvous, and capture. This two year effort, funded by the Director's Discretionary Fund is due for completion in 1992.

  8. Rendezvous with Toutatis from the Moon: The Chang'e-2 mission

    NASA Astrophysics Data System (ADS)

    Huang, J.; Tang, X.; Meng, L.

    2014-07-01

    Chang'e-2 probe was the second lunar probe of China, with the main objectives to demonstrate some key features of the new lunar soft landing technology, and its applications to future exploration missions. After completing the planned mission successfully, Chang'e-2 flew away from the Moon and entered into the interplanetary space. Later, at a distance of 7 million km from the Earth, Chang'e-2 encountered asteroid (4179) Toutatis with a very close fly-by distance and obtained colorful images with a 3-m resolution. Given some surplus velocity increment as well as the promotion of autonomous flight ability and improvement of control, propulsion, and thermal systems in the initial design, Chang'e-2 had the capabilities necessary for escaping from the Moon. By taking advantage of the unique features of the Lagrangian point, the first close fly-by of asteroid Toutatis was realized despite the tight constraints of propellant allocation, spacecraft-Earth communication, and coordination of execution sequences. Chang'e-2 realized the Toutatis flyby with a km-level distance at closest approach. In the absence of direct measurement method, based on the principle of relative navigation and through the use of the sequence of target images, we calculated the rendezvous parameters such as relative distance and image resolution. With the help of these parameters, some fine and new scientific discoveries about the asteroid were obtained by techniques of optical measurements and image processing. Starting with an innovative design, followed by high-fidelity testing and demonstration, elaborative implementation, and optimal usage of residual propellant, Chang'e-2 has for the first time successfully explored the Moon, L2 point and an asteroid, while achieving the purpose of 'faster, better, cheaper'. What Chang'e-2 has accomplished was far beyond our expectations. *J. Huang is the chief designer (PI) of Chang'e-2 probe, planned Chang'e-2's multi-objective and multitasking exploration mission.

  9. A new way in intelligent recognition improves control accuracy and efficiency for spacecrafts' rendezvous and docking

    NASA Astrophysics Data System (ADS)

    Wang, JiaQing; Lu, Yaodong; Wang, JiaFa

    2013-08-01

    Spacecrafts rendezvous and docking (RVD) by human or autonomous control is a complicated and difficult problem especially in the final approach stage. Present control methods have their key technology weakness. It is a necessary, important and difficult step for RVD through human's aiming chaser spacecraft at target spacecraft in a coaxial line by a three-dimension bulge cross target. At present, there is no technology to quantify the alignment in image recognition direction. We present a new practical autonomous method to improve the accuracy and efficiency of RVD control by adding image recognition algorithm instead of human aiming and control. Target spacecraft has a bulge cross target which is designed for chaser spacecraft's aiming accurately and have two center points, one is a plate surface center point(PSCP), another is a bulge cross center point(BCCP), while chaser spacecraft has a monitoring ruler cross center point(RCCP) of the video telescope optical system for aiming . If the three center points are coincident at the monitoring image, the two spacecrafts keep aligning which is suitable for closing to docking. Using the trace spacecraft's video telescope optical system to acquire the real-time monitoring image of the target spacecraft's bulge cross target. Appling image processing and intelligent recognition algorithm to get rid of interference source to compute the three center points' coordinate and exact digital offset of two spacecrafts' relative position and attitude real-timely, which is used to control the chaser spacecraft pneumatic driving system to change the spacecraft attitude in six direction: up, down, front, back, left, right, pitch, drift and roll precisely. This way is also practical and economical because it needs not adding any hardware, only adding the real-time image recognition software into spacecrafts' present video system. It is suitable for autonomous control and human control.

  10. Coherent Doppler lidar for automated space vehicle, rendezvous, station-keeping and capture

    NASA Astrophysics Data System (ADS)

    Dunkin, James A.

    Recent advances in eye-safe, short wavelength solid-state lasers offer real potential for the development of compact, reliable, light-weight, efficient coherent lidar. Laser diode pumping of these devices has been demonstrated, thereby eliminating the need for flash lamp pumping, which has been a major drawback to the use of these lasers in space based applications. Also these lasers now have the frequency stability required to make them useful in coherent lidar, which offers all of the advantages of non-coherent lidar, but with the additional advantage that direct determination of target velocity is possible by measurement of the Doppler shift. By combining the Doppler velocity measurement capability with the inherent high angular resolution and range accuracy of lidar it is possible to construct Doppler images of targets for target motion assessment. A coherent lidar based on a Tm,Ho:YAG 2-micrometer wavelength laser was constructed and successfully field tested on atmospheric targets in 1990. This lidar incorporated an all solid state (laser diode pumped) master oscillator, in conjunction with a flash lamp pumped slave oscillator. Solid-state laser technology is rapidly advancing, and with the advent of high efficiency, high power, semiconductor laser diodes as pump sources, all-solid-state, coherent lidars are a real possibility in the near future. MSFC currently has a feasibility demonstration effort under way which will involve component testing, and preliminary design of an all-solid-state, coherent lidar for automatic rendezvous, and capture. This two year effort, funded by the Director's Discretionary Fund is due for completion in 1992.

  11. Rendezvous, Landing and Sample Return Mission to Jupiter Trojans by the Solar Power Sail

    NASA Astrophysics Data System (ADS)

    Yano, Hajime; Matsuura, Shuji; Mori, Osamu; Yonetoku, Daisuke; Nakamura, Ryosuke; Sekine, Yasuhito; Abe, Shinsuke

    JAXA/ISAS has been preparing for the Solar Power Sail mission, Japan’s first outer planet region exploration. Its precursor was successfully realized by IKAROS, the world's first deep space solar sail spacecraft, in 2010 between the Earth and Venus orbits. The Solar Power Sail is defined primarily as a technology demonstration mission; yet it will also present game-changing opportunities for both space astronomy and solar system exploration. The former will benefit the cruising operation, which will enable ”dust free” infrared astronomy beyond the cocoon of the zodiacal light to search for the first generation light of the Universe. Interplanetary-long baseline will allow gamma-ray burst observation to identify their source locations much more precise than ever. As for solar system exploration, the Solar Power Sail, which is not depended upon RTG technology, will offer the world's first possibility of rendezvous, landing and sample return from the outer planet region, i.e., in the Jupiter region and beyond. With this technology, we are aiming to visit Jupiter Trojan asteroids, one of the last uncharted frontiers of the Solar System. Jupiter Trojans may hold fundamental clues of the Solar System formation and revolution discussed by two competing hypotheses between the classic model and the planetary migration model. The former suggests that Trojan asteroids are mainly survivors of building blocks of the Jupiter system, while the latter claims that they must be intruders from outer regions after the planetary migration of gas planets settled. This paper outlines scientific objectives of Jupiter Trojan exploration, its mission design and major aspects of the spacecraft system, nature of candidate target asteroids, in-situ observation and lander instruments including optical camera, imaging spectrometer, high-resolution TOF mass spectrometer, and large-area dust counter, together with a strategy of the sample return option from the surface of a Trojan asteroid.

  12. A Prediction Method of TV Camera Image for Space Manual-control Rendezvous and Docking

    NASA Astrophysics Data System (ADS)

    Zhen, Huang; Qing, Yang; Wenrui, Wu

    Space manual-control rendezvous and docking (RVD) is a key technology for accomplishing the RVD mission in manned space engineering, especially when automatic control system is out of work. The pilot on chase spacecraft manipulates the hand-stick by the image of target spacecraft captured by TV camera. From the TV image, the relative position and attitude of chase and target spacecrafts can be shown. Therefore, the size, the position, the brightness and the shadow of the target on TV camera are key to guarantee the success of manual-control RVD. A method of predicting the on-orbit TV camera image at different relative positions and light conditions during the process of RVD is discussed. Firstly, the basic principle of capturing the image of cross drone on target spacecraft by TV camera is analyzed theoretically, based which the strategy of manual-control RVD is discussed in detail. Secondly, the relationship between the displayed size or position and the real relative distance of chase and target spacecrafts is presented, the brightness and reflection by the target spacecraft at different light conditions are decribed, the shadow on cross drone caused by the chase or target spacecraft is analyzed. Thirdly, a prediction method of on-orbit TV camera images at certain orbit and light condition is provided, and the characteristics of TV camera image during the RVD is analyzed. Finally, the size, the position, the brightness and the shadow of target spacecraft on TV camera image at typical orbit is simulated. The result, by comparing the simulated images with the real images captured by the TV camera on Shenzhou manned spaceship , shows that the prediction method is reasonable

  13. Mechanisms and Rates of Bacterial Colonization of Sinking Aggregates

    PubMed Central

    Kiørboe, Thomas; Grossart, Hans-Peter; Ploug, Helle; Tang, Kam

    2002-01-01

    Quantifying the rate at which bacteria colonize aggregates is a key to understanding microbial turnover of aggregates. We used encounter models based on random walk and advection-diffusion considerations to predict colonization rates from the bacteria's motility patterns (swimming speed, tumbling frequency, and turn angles) and the hydrodynamic environment (stationary versus sinking aggregates). We then experimentally tested the models with 10 strains of bacteria isolated from marine particles: two strains were nonmotile; the rest were swimming at 20 to 60 ?m s?1 with different tumbling frequency (0 to 2 s?1). The rates at which these bacteria colonized artificial aggregates (stationary and sinking) largely agreed with model predictions. We report several findings. (i) Motile bacteria rapidly colonize aggregates, whereas nonmotile bacteria do not. (ii) Flow enhances colonization rates. (iii) Tumbling strains colonize aggregates enriched with organic substrates faster than unenriched aggregates, while a nontumbling strain did not. (iv) Once on the aggregates, the bacteria may detach and typical residence time is about 3 h. Thus, there is a rapid exchange between attached and free bacteria. (v) With the motility patterns observed, freely swimming bacteria will encounter an aggregate in <1 day at typical upper-ocean aggregate concentrations. This is faster than even starving bacteria burn up their reserves, and bacteria may therefore rely solely on aggregates for food. (vi) The net result of colonization and detachment leads to a predicted equilibrium abundance of attached bacteria as a function of aggregate size, which is markedly different from field observations. This discrepancy suggests that inter- and intraspecific interactions among bacteria and between bacteria and their predators may be more important than colonization in governing the population dynamics of bacteria on natural aggregates. PMID:12147501

  14. MICHEL PATY CONSTRUCTION MATHEMATIQUE ET REALITEDE L'ESPACE-TEMPS DE LA RELATIVITE 1 in Piettre, Bernard (dir.), Le temps et ses reprsentations, coll. Les Rendez-vous

    E-print Network

    Paris-Sud XI, Université de

    MICHEL PATY CONSTRUCTION MATHEMATIQUE ET REALITEDE L'ESPACE-TEMPS DE LA RELATIVITE 1 in Piettre, Bernard (dir.), Le temps et ses représentations, coll. Les Rendez-vous d'Archimède, L'Harmattan, Paris, 2001, p. 79-106. L'espace-temps de la théorie de la relativité par Michel PATY* RÉSUMÉ. L'espace-temps

  15. Multi-robot exploration of unknown environments with identification of exploration completion and post-exploration rendez-vous using ant

    E-print Network

    Paris-Sud XI, Université de

    Multi-robot exploration of unknown environments with identification of exploration completion and post-exploration rendez-vous using ant algorithms Mihai Andries1,2,3 and Franc¸ois Charpillet1 is to autonomously explore an unknown environment. When the coverage is com- pleted, all robots move to a previously

  16. TASTER: Trojan ASteroid Tour, Exploration and Rendezvous, a NASA Planetary Science Summer School Mission Design Exercise

    NASA Astrophysics Data System (ADS)

    Diaz-silva, R.; Sayanagi, K. M.; Gil, S.; Diniega, S.; Balcerski, J.; Benneke, B.; Carande, B.; Fraeman, A. A.; Hudson, J. S.; Guzewich, S. D.; Livi, R.; Nahm, A.; Potter, S.; Route, M.; Urban, K. D.; Vasisht, S.; Williams, B.; Budney, C. J.; Lowes, L. L.

    2011-12-01

    A detailed investigation of the Trojan asteroids occupying Jupiter's L4 and L5 Lagrangian points has been identified as a priority for future missions by the 2011 Planetary Science Decadal Survey. Observing these asteroids and getting clear measurements of their physical characteristics and composition may yield answers to fundamental questions relating to the early Solar System. In particular, Trojan asteroids are believed to harbor primordial material dating from the time of its formation. The source region for Trojans is still unknown; the Nice model predicts that some bodies may have originated in the primordial Kuiper belt and were subsequently scattered inward during the migration of Neptune and Uranus and settled in their current location. In alternative models, less radial scattering of small bodies would imply Trojans formed from material at a similar orbital distance to Jupiter. Determination of Trojan composition and structure will help identify their birth location, provide information about the impact history and subsequent evolution. Earth-based observations of size and surface characteristics are sparse; spectral measurements are unable to resolve composition (and show a puzzling lack of volatile signatures), indicating that close-range observation is needed. We present a mission design for a Trojan Tour and Rendezvous mission that is consistent with NASA's New Frontiers candidate recommended by the Decadal Survey, and which is the final result of the 2011 NASA-JPL Planetary Science Summer School Mission Design Exercise. Our proposed mission includes a tour phase that features a 500 km altitude fly-by of 1999 XS143. The spacecraft will then orbit and make detailed observations of 1919FD Agamemnon, a 167 km diameter asteroid located in the leading Lagrangian point (L4), from orbital altitudes of 1000 - 100 km over a 12 month nominal science data capture period. The mission's planned primary observations aim to (1) detect and identify volatile species and rock-forming elements on or just below the surface, (2) map the surface geology, and (3) determine size, shape, and rotational state. Our payload will provide unprecedented high-resolution, global dataset for the target bodies, yielding crucial information about the early history and evolution of the Solar System.

  17. Tumbling motions of [NH2(CH3)2]+ ions in [NH2(CH3)2]2CoCl4 determined by 1H MAS NMR spectroscopy in the rotating frame

    NASA Astrophysics Data System (ADS)

    Yoon, Ma Byong; Bong, Pill Hoon; Lim, Ae Ran

    2015-03-01

    The structure and phase transition temperatures of [NH2(CH3)2]2CoCl4 were determined using X-ray diffraction and differential scanning calorimetry, respectively. The temperature dependence of chemical shifts and the spin-lattice relaxation time T1? in the rotating frame were measured for the 1H nucleus in [NH2(CH3)2]2CoCl4. T1? for 1H in [NH2(CH3)2]2CoCl4 showed a minimum, and it is apparent that T1? values are governed by a tumbling motion. The activation energy of tumbling motion for 1H is owing to the interaction between CH3 and NH2 ions in the [NH2(CH3)2]+ group.

  18. Rosetta rendezvous and CONSERT operations in 2014: A chimeric surface model of 67P/Churyumov Gerasimenko

    NASA Astrophysics Data System (ADS)

    Herique, Alain; Lasue, Jéremie; Rogez, Yves; Zine, Sonia; Kofman, Wlodek

    2012-07-01

    In 2014 the European Space Agency's Rosetta probe will rendezvous with the comet 67P/Churyumov Gerasimenko (67P) and the Philae Lander will land on the surface of the nucleus. Following the landing, the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) radar will perform the tomography of the nucleus by measuring radiowave propagation through the comet between the Lander and the orbiter. Preparation for these operations, in particular the development and validation of simulation software, requires a shape model of the surface of 67P. The complexity of this model should reflect the environmental conditions that will be found in 2014. In this paper, we show that existing models of 67P are not of a sufficiently high resolution to constitute interesting test cases. Following a review of current shape models for other comets, we propose a composite which is a hybrid of the 67P and 81P/Wild 2 models.

  19. Modified technique of laparoendoscopic rendezvous ERCP during laparoscopic cholecystectomy for concomitant gallstone and common bile ductal stone.

    PubMed

    Liu, Wei; Wang, Qunwei; Huang, Jiangsheng; Liu, Luyao; Li, Pengfei; Xiao, Jing; Zhao, Liying

    2014-09-01

    Laparoendoscopic rendezvous ERCP and laparoscopic cholecystectomy (LC+ERCP/LERV) is considered an optimal approach for concomitant gallstone and common bile duct stone, but this procedure could be failed due to some technical challenges. We describe a modified technique which was adopted in 32 consecutive cases and yielded good results. A Dormia basket is inserted through cystic duct to enter duodenum and grasp the guide wire which is introduced with sphincterotome through endoscope. After pulling the basket catheter and guide wire into bile duct, the selective bile duct cannulation could be achieved by advancing sphinterotome over guide wire. An atraumatic clamp is also used to temporarily occlude proximal jejunum preventing diffuse bowel distention by air insufflation. The procedure was successfully performed in 31 cases(96.8%) , the mean operative time and endoscopic time were 82.6±19.6 min and 26.5±5.99min, respectively. This modified technique is safe, feasible and associated with short operative time. PMID:25436338

  20. An Investigation of Multipath Effects on the GPS System During Auto-Rendezvous and Capture

    NASA Technical Reports Server (NTRS)

    Richie, James E.; Forest, Francis W.

    1995-01-01

    The proposed use of a Cargo Transport Vehicle (CTV) to carry hardware to the Space Station Freedom (SSF) during the construction phase of the SSF project requires remote maneuvering of the CTV. The CTV is not a manned vehicle. Obtaining the relative positions of the CTV and SSF for remote auto-rendezvous and capture (AR&C) scenarios will rely heavily on the Global Positioning System (GPS). The GPS system is expected to guide the CTV up to a distance of 100 to 300 meters from the SSF. At some point within this range, an optical docking system will take over the remote guidance for capture. During any remote guidance by GPS it is possible that significant multipath signals may be caused by large objects in the vicinity of the module being remotely guided. This could alter the position obtained by the GPS system from the actual position. Due to the nature of the GPS signals, it has been estimated that if the difference in distance between the Line of Sight (LOS) path and the multipath is greater than 300 meters, the GPS system is capable of discriminating between the direct signal and the reflected (or multipath) signal. However, if the path difference is less than 300 meters, one must be concerned. This report details the work accomplished by the Electromagnetic Simulations Laboratory at Marquette University over the period December 1993 to May 1995. This work is an investigation of the strength and phase of a multipath signal arriving at the CTV relative to the direct or line of sight (LOS) signal. The signal originates at a GPS satellite in half geo-stationary orbit and takes two paths to the CTV: (1) the direct or LOS path from the GPS satellite to the CTV; and (2) a scattered path from the GPS satellite to the SSF module and then to the CTV. The scattering from a cylinder has been computed using the physical optics approximation for the current. No other approximations or assumptions have been made including no assumptions regarding the far field or Fresnel field approximations. The integrations required to obtain the scattered field have been computed numerically using an N dimensional Romberg integration. The total scattered electric field is then projected onto the RCP component in the direction of propagation only. The direct or line of sight signal is then used to compute the relative strength and phase of the scattered field. The trajectory of the CTV has been parameterized into 4,214 points that are calculated for each of the geometries investigated. The motion of the CTV between points is small enough for the magnitude data (dB down from direct signal) to appear very smooth; however, because of the distances and wavelengths involved, the phase of the scattered field relative to the direct signal varies very rapidly.

  1. Laser rangefinder for the near-earth asteroid rendezvous (NEAR) mission

    NASA Astrophysics Data System (ADS)

    Cole, Timothy D.; Boies, Mark T.; El-Dinary, Ashruf S.; Reiter, R. Alan; Rodriguez, Daniel E.; Heins, Robert J.; Le, Binh Q.; Moore, Robert C.; Grote, Michael G.; Culpepper, Charles; Stillman, Lee

    1995-12-01

    The near-earth asteroid rendezvous (NEAR) mission is the first of the NASA discovery programs. Discovery-class programs emphasize small, low-cost, quick turnaround space missions that provide significant science returns. The NEAR spacecraft and ground control system are currently being developed and tested at the Applied Physics Laboratory (APL). The NEAR spacecraft will orbit, 433 Eros, possibly the most studied of the near-Earth asteroids. Subsequent to a 3-year cruise, the NEAR spacecraft is inserted into a 50-km-altitude orbit about Eros for 1 year to permit data collection in the infrared, visible, x-ray and gamma-ray regions. One instrument, the NEAR laser rangefinder (NLR), will provide altimetry data useful in characterizing the geophysical nature of Eros. In addition, ranging data from the NLR will support navigation functions associated with spacecraft station-keeping and orbit maintenance. The NLR instrument uniquely applies several technologies for use in space. Our configuration uses a direct-detection, bistatic design employing a gallium arsenide (GaAs) diode-pumped Cr:Nd:YAG laser for the 1.064-micrometer transmitter and an enhanced-silicon avalanche-photodiode (APD) detector for the receiver. Transmitter pulse energy provides the required signal-to-noise power ratio, SNRp, for reliable operation at 50 km. The selected APD exhibited low noise, setting the level achievable for noise equivalent power, NEP, by the receiver. The lithium-niobate (LiNbO3) Q-switched transmitter emits 12-ns pulses at 15.3 mJ/pulse, permitting reliable NLR operation beyond the required 50-km altitude. Cavity aperturing and a 9.3X Galilean telescope reduce beam divergence for high spatial sampling of Eros's surface. Our receiver design is an f/3.4 Dall-Kirkham Cassegrain with a 7.62-cm clear aperture -- we emphasized receiver aperture area, Arx, over transmitter power, Pt, in our design based on the range advantage attainable according to the simplified range equation, Rmax equals [(Pt(rho) BArx)/(SNRp NEP)]1/2. Asteroid reflectivity, (rho) B, is estimated to be 0.05 at our wavelength. A reasonable power signal- to-noise ratio for reliable operation, SNRp, was assumed. To minimize our noise equivalent power, NEP, we carefully designed and selected the receiver components. The receiver circuit uses leading-edge detection of the laser backscatter. Our detector circuit is an enhanced-silicon APD hybrid using a video amplifier, an integrating Bessel filter, and a high- speed programmable threshold comparator. We accomplish time-of-flight (TOF) measurements digitally with an APL-designed GaAs application-specific integrated circuit. A radiation-hardened FORTH microprocessor controls range gating, data collection and formatting, and operational modes. Implementation of control and data communications between the spacecraft and rangefinder uses the MIL-STD 1553-bus architecture. Functional testing and calibration indicate exceptional performance; return power levels were reliably detected over several thresholds with 71-dB attenuation, while observed range jitter was equivalent to the resolution determined by the TOF GaAs chip (31.5 cm). This paper discusses NLR performance requirements, design implementation, and qualification testing. It also provides preliminary results from calibration and performance testing.

  2. A guidance, navigation and control system for Rendezvous and proximity operations between Hermes, the Columbus Free Flyer and the Space Station Freedom

    Microsoft Academic Search

    Wigbert Fehse; Alberto Tobias; Calixte Champetier; Jean-Michel Pairot; Christian Pauvert

    1991-01-01

    A Rendez-Vous and Docking Proof-of-Concept Programme has been recently initiated by ESA, covering RV and proximity operations between Hermes, the Columbus Free Flyer and the Space Station Freedom. A complete RV System has been designed on the basis of the commonalities between the Hermes and the Columbus projects. Requirements have been derived, and software and hardware elements have been developed

  3. Coordinated Radio, Electron, and Waves Experiment (CREWE) for the NASA Comet Rendezvous and Asteroid Flyby (CRAF) instrument

    NASA Technical Reports Server (NTRS)

    Scudder, Jack D.

    1992-01-01

    The Coordinated Radio, Electron, and Waves Experiment (CREWE) was designed to determine density, bulk velocity and temperature of the electrons for the NASA Comet Rendezvous and Asteroid Flyby Spacecraft, to define the MHD-SW IMF flow configuration; to clarify the role of impact ionization processes, to comment on the importance of anomalous ionization phenomena (via wave particle processes), to quantify the importance of wave turbulence in the cometary interaction, to establish the importance of photoionization via the presence of characteristic lines in a structured energy spectrum, to infer the presence and grain size of significant ambient dust column density, to search for the theoretically suggested 'impenetrable' contact surface, and to quantify the flow of heat (in the likelihood that no surface exists) that will penetrate very deep into the atmosphere supplying a good deal of heat via impact and charge exchange ionization. This final report provides an instrument description, instrument test plans, list of deliverables/schedule, flight and support equipment and software schedule, CREWE accommodation issues, resource requirements, status of major contracts, an explanation of the non-NASA funded efforts, status of EIP and IM plan, descope options, and Brinton questions.

  4. The Space Operations Simulation Center (SOSC) and Closed-Loop Hardware Testing for Orion Rendezvous System Design

    NASA Technical Reports Server (NTRS)

    Milenkovic, Zoran; DSouza, Christopher; Huish, David; Bendle, John; Kibler, Angela

    2012-01-01

    The exploration goals of Orion / MPCV Project will require a mature Rendezvous, Proximity Operations and Docking (RPOD) capability. Ground testing autonomous docking with a next-generation sensor such as the Vision Navigation Sensor (VNS) is a critical step along the path of ensuring successful execution of autonomous RPOD for Orion. This paper will discuss the testing rationale, the test configuration, the test limitations and the results obtained from tests that have been performed at the Lockheed Martin Space Operations Simulation Center (SOSC) to evaluate and mature the Orion RPOD system. We will show that these tests have greatly increased the confidence in the maturity of the Orion RPOD design, reduced some of the latent risks and in doing so validated the design philosophy of the Orion RPOD system. This paper is organized as follows: first, the objectives of the test are given. Descriptions of the SOSC facility, and the Orion RPOD system and associated components follow. The details of the test configuration of the components in question are presented prior to discussing preliminary results of the tests. The paper concludes with closing comments.

  5. Tumbling motions of NH2(CH3)2 ions in [NH2(CH3)2]2ZnCl4 studied using 1H MAS NMR and 13C CP/MAS NMR

    NASA Astrophysics Data System (ADS)

    Kim, Nam Hee; Choi, Jae Hun; Lim, Ae Ran

    2014-12-01

    The structure and the phase transition temperatures of [NH2(CH3)2]2ZnCl4 were determined using X-ray diffraction and DSC, respectively. The temperature dependence of chemical shifts and the spin-lattice relaxation time T1? in the rotating frame were measured for the 1H and 13C nuclei in [NH2(CH3)2]2ZnCl4. From these results, it was observed that the structural change by chemical shifts does not occur with temperature. However, T1? for 1H and 13C in [NH2(CH3)2]2ZnCl4 showed a minimum, and it is apparent that both T1? values are governed by the same tumbling motions. The activation energies of tumbling motions for 1H and 13C are nearly the same owing to the connection between CH3 and NH2 ions in the [NH2(CH3)2]+ group.

  6. Cosmic Ray Induced Degradation in X-Ray Detectors On Board the Near Earth Asteroid Rendezvous Spacecraft

    NASA Astrophysics Data System (ADS)

    Floyd, S. R.; Trombka, J. I.; Goldsten, J. O.; Fiore, E. M.

    The Near-Earth Asteroid Rendezvous (NEAR) mission is the first in NASA's new Discovery Program to explore the solar system. Launched in February 1996, the NEAR spacecraft will take a long cruise flight arriving at the asteroid 433 Eros in January 1999 for a one year orbiting survey operation. This long exposure to the space environment has already proven to be an additional complication for the x-ray spectrometer. The asteroid pointing detectors for the x-ray spectrometer are three gas-filled proportional counters with resolving power in the range of 1 keV. Therefore, to resolve the important but closely spaced magnesium, aluminum and silicon k alpha lines( 1.255, 1.487, 1.739 keV respectively), magnesium and aluminum balanced filters are used on two of the detectors. The x-ray florescence from the surface of Eros is stimulated by solar x-rays. A proportional counter and a silicon PIN detector are used to monitor the solar incident x-ray flux. The proportional counters are single wire gas filled beryllium lined steel tubes operating at about 1100 volt. The 25 cm2 optical window is one mil. thick beryllium. To define the detector's active region, two boron nitride disks were incorporated in the tube just outside window area. It appears from the space flight data that the space environment is creating a charge on these boron nitride disks which ultimately distorts the tube gain and resolution. This broadening of the photo peak makes it more difficult to identify weak peaks and so degrades the statistical accuracy for some very important elements such as sulfur, calcium and iron (2.307, 3.690, 6.403 keV respectively). If the broadening is severe enough in the low energy region, counts will be lost as the photo peak spreads below the lower level discriminator (0.7 keV).

  7. Cosmic Ray Induced Degradation in X-Ray Detectors On Board the Near Earth Asteroid Rendezvous Spacecraft

    NASA Technical Reports Server (NTRS)

    Floyd, S. R.; Trombka, J. I.; Goldsten, J. O.; Fiore, E. M.

    1997-01-01

    The Near-Earth Asteroid Rendezvous (NEAR) mission is the first in NASA's new Discovery Program to explore the solar system. Launched in February 1996, the NEAR spacecraft will take a long cruise flight arriving at the asteroid 433 Eros in January 1999 for a one year orbiting survey operation. This long exposure to the space environment has already proven to be an additional complication for the x-ray spectrometer. The asteroid pointing detectors for the x-ray spectrometer are three gas-filled proportional counters with resolving power in the range of 1 keV. Therefore, to resolve the important but closely spaced magnesium, aluminum and silicon k alpha lines( 1.255, 1.487, 1.739 keV respectively), magnesium and aluminum balanced filters are used on two of the detectors. The x-ray florescence from the surface of Eros is stimulated by solar x-rays. A proportional counter and a silicon PIN detector are used to monitor the solar incident x-ray flux. The proportional counters are single wire gas filled beryllium lined steel tubes operating at about 1100 volt. The 25 cm(exp 2) optical window is one mil. thick beryllium. To define the detector's active region, two boron nitride disks were incorporated in the tube just outside window area. It appears from the space flight data that the space environment is creating a charge on these boron nitride disks which ultimately distorts the tube gain and resolution. This broadening of the photo peak makes it more difficult to identify weak peaks and so degrades the statistical accuracy for some very important elements such as sulfur, calcium and iron (2.307, 3.690, 6.403 keV respectively). If the broadening is severe enough in the low energy region, counts will be lost as the photo peak spreads below the lower level discriminator (0.7 keV).

  8. Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission

    NASA Technical Reports Server (NTRS)

    Hinkel, Heather; Strube, Matthew; Zipay, John J.; Cryan, Scott

    2015-01-01

    This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR and D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR and D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR and D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a threedimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR and D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

  9. Technology Development of Automated Rendezvous and Docking/Capture Sensors and Docking Mechanism for the Asteroid Redirect Crewed Mission

    NASA Technical Reports Server (NTRS)

    Hinkel, Heather; Cryan, Scott; Zipay, John; Strube, Matthew

    2015-01-01

    This paper will describe the technology development efforts NASA has underway for Automated Rendezvous and Docking/Capture (AR&D/C) sensors and a docking mechanism and the challenges involved. The paper will additionally address how these technologies will be extended to other missions requiring AR&D/C whether robotic or manned. NASA needs AR&D/C sensors for both the robotic and crewed segments of the Asteroid Redirect Mission (ARM). NASA recently conducted a commonality assessment of the concept of operations for the robotic Asteroid Redirect Vehicle (ARV) and the crewed mission segment using the Orion crew vehicle. The commonality assessment also considered several future exploration and science missions requiring an AR&D/C capability. Missions considered were asteroid sample return, satellite servicing, and planetary entry, descent, and landing. This assessment determined that a common sensor suite consisting of one or more visible wavelength cameras, a threedimensional LIDAR along with long-wavelength infrared cameras for robustness and situational awareness could be used on each mission to eliminate the cost of multiple sensor developments and qualifications. By choosing sensor parameters at build time instead of at design time and, without having to requalify flight hardware, a specific mission can design overlapping bearing, range, relative attitude, and position measurement availability to suit their mission requirements with minimal nonrecurring engineering costs. The resulting common sensor specification provides the union of all performance requirements for each mission and represents an improvement over the current systems used for AR&D/C today. These sensor specifications are tightly coupled to the docking system capabilities and requirements for final docking conditions. The paper will describe NASA's efforts to develop a standard docking system for use across NASA human spaceflight missions to multiple destinations. It will describe the current design status and the considerations and technologies involved in developing this docking mechanism.

  10. Thermo-physical properties of 162173 (1999 JU3), a potential flyby and rendezvous target for interplanetary missions

    NASA Astrophysics Data System (ADS)

    Müller, T. G.; ?urech, J.; Hasegawa, S.; Abe, M.; Kawakami, K.; Kasuga, T.; Kinoshita, D.; Kuroda, D.; Urakawa, S.; Okumura, S.; Sarugaku, Y.; Miyasaka, S.; Takagi, Y.; Weissman, P. R.; Choi, Y.-J.; Larson, S.; Yanagisawa, K.; Nagayama, S.

    2011-01-01

    Context. Near-Earth asteroid 162173 (1999 JU3) is a potential flyby and rendezvous target for interplanetary missions because of its easy-to-reach orbit. The physical and thermal properties of the asteroid are relevant for establishing the scientific mission goals and also important in the context of near-Earth object studies in general. Aims: Our goal was to derive key physical parameters such as shape, spin-vector, size, geometric albedo, and surface properties of 162173 (1999 JU3). Methods: With three sets of published thermal observations (ground-based N-band, Akari IRC, Spitzer IRS), we applied a thermophysical model to derive the radiometric properties of the asteroid. The calculations were performed for the full range of possible shape and spin-vector solutions derived from the available sample of visual lightcurve observations. Results: The near-Earth asteroid 162173 (1999 JU3) has an effective diameter of 0.87 ± 0.03 km and a geometric albedo of 0.070 ± 0.006. The ?2-test reveals a strong preference for a retrograde sense of rotation with a spin-axis orientation of ?ecl = 73°, ?ecl = -62° and Psid = 7.63 ± 0.01 h. The most likely thermal inertia ranges between 200 and 600 J m-2 s-0.5 K-1, about a factor of 2 lower than the value for 25143 Itokawa. This indicates that the surface lies somewhere between a thick-dust regolith and a rock/boulder/cm-sized, gravel-dominated surface like that of 25143 Itokawa. Our analysis represents the first time that shape and spin-vector information has been derived from a combined data set of visual lightcurves (reflected light) and mid-infrared photometry and spectroscopy (thermal emission).

  11. Deburring by centrifugal barrel tumbling

    Microsoft Academic Search

    Gillespie

    1976-01-01

    The reliability of small precision mechanisms greatly depends upon the production of burr-free, sharp-edged parts. Centrifugal barrel finishing (Harperizing) is one of the few processes capable of producing these conditions. Burrs less than 0.001-in. thick by 0.001-in. high (25.4 x 25.4 ..mu..m) can be removed from 303 Se stainless steel, 1018 steel, and 6061-T6 aluminum with dimensional changes in the

  12. Tumbling sandpiles in a fluid

    NASA Astrophysics Data System (ADS)

    Radjai, Farhang; Topin, Vincent; Perales, Frédéric; Monerie, Yann

    2013-06-01

    By means of contact dynamics simulations interfaced with computational fluid dynamics, we analyze the effect of a suspending fluid on the dynamics of collapse and spread of a granular column. We find that the runout distance increases as a power law with the aspect ratio of the column and, for a given aspect ratio, it may be the same in the grain-inertial and fluid-inertial regimes but with considerably longer duration in the latter case. We show that, in both viscous and fluid-inertial regimes, this behavior results from compensation between two effects of the fluid: 1) reduction of the kinetic energy during collapse and 2) enhancement of the flow by lubrication during spread.

  13. A Modified Technique Reduced Operative Time of Laparoendoscopic Rendezvous Endoscopic Retrograde Cholangiopancreatography Combined with Laparoscopic Cholecystectomy for Concomitant Gallstone and Common Bile Ductal Stone

    PubMed Central

    Liu, Wei; Wang, Qunwei; Xiao, Jing; Zhao, Liying; Huang, Jiangsheng; Tan, Zhaohui; Li, Pengfei

    2014-01-01

    Laparoendoscopic rendezvous (LERV) endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic cholecystectomy (LC+ERCP/LERV) are considered an optimal approach for concomitant gallstones and common bile duct stones. The rendezvous technique is essential for the success of procedure. We applied two different LERV techniques, traditional technique and modified technique, in 60 consecutive cases from January 2011 to November 2012. 32 cases who underwent modified technique (group 1) from February 2012 to November 2012 were retrospectively compared to 28 cases (group 2) who underwent traditional technique from January 2011 to January 2012. There was no significant difference between two groups with respect to preoperative demographic features. Although the difference was not statistically significant, the procedure was successfully performed in 31 cases (96.9%) in group 1 and 24 cases (86.2%) in group 2. The mean operative time and time of endoscopic part were 82.6?±?19.6?min and 26.5?±?5.99?min in group 1 which were significantly shorter than those in group 2 (118.0?±?23.1?min and 58.7?±?13.3?min, resp.). There was no postoperative pancreatitis and mortality in both groups. The mean hospital stay, blood loss, incidence of complications, and residual stone were of no difference in both groups. This study proved that this modified technique can effectively reduce the operative time and time of endoscopic part of LC+ERCP/LERV compared with traditional technique. PMID:25024701

  14. Precise Attitude Determination for Rendez-Vous and Docking by Information Fusion of Laser Range Finder Measurements

    NASA Astrophysics Data System (ADS)

    Strietzel, Roland

    For the docking of spacecrafts a highly precise attitude and position control is necessary. This requires an adequate measurement of the relative position and attitude of the docking spacecrafts. Here is presented, how a rendezvous and docking sensor (RVS) consisting of a laser range finder (LRF) with a scanning mirror system and a set of retro reflectors can be used to measure the necessary data. The active part of the measurement system is mounted on the chaser. The passive part forms the target pattern and is a set of three or more retro reflectors mounted on the space station. A laser beam scans the field of view and detects the range and the line of sight of each retro reflector of the target successively (Fig. 1). The sequence of the LRF measurements of the moving chaser is processed in a special multi-model state observer (Fig. 2). In this way the results of the retro measurements are composed to the relative position and attitude between chaser and target. Because of the sequential measurement y of the single retro reflectors from the moving chaser, a precise determination of the attitude can only be performed, if all the state variables x* of position and attitude with the belonging velocities of the rigid chaser are estimated. The availability of the complete state vector also supports the application of state feedback control of the chaser motion. Fig. 1. Scanning laser radar with target pattern Fig. 2. Multi-model state observer for sequential retro measurements (right) The observer computes with increasing accuracy in time the 12 state variables of relative position and attitude (Euler angles or quaternions) with respect to the target as well as the translatory and rotatory velocities. It models a reduced discrete-time state equation system (k, ) of the chaser and the LRF measurements to the different retro reflectors. So for each retro reflector a partial model depending on its position in the target pattern exists (As, C). Information fusion to reduce the uncertainty of the state vector means, that each retro reflector measurement gives a specific contribution to determine the state variables and to increase their accuracy in the sequence. The dynamic behaviour of the observer, its stability, its approaching behaviour and its accuracy depend mainly on the set of observer feedback matrices H and the initial conditions of the state vector x*(0) to be estimated. The obtained algorithms are simulated under the conditions of a usual flight scenario and the results are discussed. A short observer transient time of 4 or 5 measurement cycles k can be reached.

  15. Light scattering observations and simulations, as hints about the media encountered by future rendezvous missions to comets and asteroids

    NASA Astrophysics Data System (ADS)

    Levasseur-Regourd, Anny-Chantal

    The success of future rendezvous mission to comets (i.e. Rosetta, which will explore the innermost coma of 67P/Churyumov-Gerasimenko, before deploying a lander on its nucleus in 2014) and asteroids (e.g. Marco-Polo candidate mission for ESA Cosmic Vision) require some understanding of the physical properties of the dust particles encountered in the coma (if any) and on the solid surface. Analysis of observations of the linear polarization of solar light scattered by such media may provide clues to their properties [1]. The polarization is actually a dimension-less ratio, which only varies with the geometry of the observations (i.e. phase angle), with the wavelength, and with the properties of the scattering medium. Comparisons between the shapes of the polarimetric phase curves of asteroids [2] and comets [3] provide a classification with respect to the dust properties. As far as asteroids are concerned, this classification is reminiscent of the taxonomic classes, and more information is expected from detailed studies of the wavelength dependence. As far as comets are concerned, an extensive programme of numerical and laboratory simulations with various irregular compact grains and aggregates has been developed in the past years [4,5]. Comparisons of the results with observations (tentatively on a large range of phase angles and wavelengths) have allowed us to suggest that cometary dust particles are built of both very fluffy aggregates and of more compact grains, with significant proportions of both rather transparent silicates and absorbing materials [6]. These estimations are confirmed by the analysis of Stardust samples, with, e.g. evidence for dense grains and aggregates with low bulk density within the coma of comet Wild 2 [7]. It may thus be concluded that the analysis of remote light scattering observations allows us to infer some properties of the scattering media, to point out some similarities and discrepancies between small solar system bodies, and to contribute to the success of future space missions. [1] Levasseur-Regourd and Hadamcik, J. Quant. Spectros. Radiat. Transfer 79, 903-910, 2003. [2] Pentill¨ et al., Astron. Astrophys. 432, 1081-1090, 2005. [3] Levasseur-Regourd a et al., Astron. Astrophys. 313, 327-333, 1996. [4] Lasue and Levasseur-Regourd, J. Quant. Spectros. Radiat. Transfer 100, 220-236, 2006. [5] Hadamcik et al., Icarus 190, 660-671, 2007. [6] Levasseur-Regourd et al., Planet. Space Sci. 55, 1010-1020, 2007. [7] H¨rz et al., Science o 314, 1716-1719 (2006).

  16. In-Flight Operation of the Dawn Ion Propulsion System: Status at One Year from the Vesta Rendezvous

    NASA Technical Reports Server (NTRS)

    Garner, Charles E.; Rayman, Marc D.

    2010-01-01

    The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218 kg spacecraft into an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide most of the delta V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer among Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer among Ceres science orbits. The Dawn ion thruster [I thought we only called it a thruster. Both terms are used in the paper, but I think a replacement of every occurrence of "engine" with "thruster" would be clearer.] design is based on the design validated on NASA's Deep Space 1 (DS1) mission. However, because of the very substantial (11 km/s) delta V requirements for this mission Dawn requires two engines to complete its mission objectives. The power processor units (PPU), digital control and interface units (DCIU) slice boards and the xenon control assembly (XCA) are derivatives of the components used on DS1. The DCIUs and thrust gimbal assemblies (TGA) were developed at the Jet Propulsion Laboratory. The spacecraft was provided by Orbital Sciences Corporation, Sterling, Virginia, and the mission is managed by and operated from the Jet Propulsion Laboratory. Dawn partnered with Germany, Italy and Los Alamos National Laboratory for the science instruments. The mission is led by the principal investigator, Dr. Christopher Russell, from the University of California, Los Angeles. The first 80 days after launch were dedicated to the initial checkout of the spacecraft followed by cruise to Mars. Cruise thrusting leading to a Mars gravity assist began on December 17, 2007 and was successfully concluded as planned on October 31, 2008. During this time period the Dawn IPS was operated mostly at full power for approximately 6500 hours, consumed 71.7 kg of xenon and delivered approximately 1.8 km/s of delta V to the spacecraft. The thrusting to Mars was followed by a coasting period of approximately 3.5 months that included a Mars flyby in February of 2009. The Mars flyby provided a gravity assist (MGA) for a plane change and approximately 1 km/s of heliocentric energy increase and is the only part of the mission following launch in which a needed velocity change is not accomplished by the IPS. During the coast period IPS was operated for a trajectory correction maneuver and for engineering tests but was not operated for primary propulsion. Closest approach to Mars occurred as planned on February 17, 2009 and was followed by another coasting period of just under 4 months in duration. During this last coasting phase IPS was operated only for routine maintenance activities and for system engineering tests. Deterministic thrusting for heliocentric transfer to Vesta resumed on June 8, 2009. Since resumption of cruise to Vesta IPS has been operated at throttled power levels, most of the time at full power, and with a duty cycle of approximately 93%, leading to an arrival at Vesta in July of 2011 and arrival at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through one year from the spacecraft's rendezvous with Vesta.

  17. Mountain Man Measurement Rendezvous

    NSDL National Science Digital Library

    Utah LessonPlans

    2012-10-22

    In this math lesson, learners participate in several activities where they apply measurement skills. Learners explore how the Mountain Men played an important part in the history of the American frontier and more importantly, how the Mountain Men used different techniques for making measurements in their daily activities. At the various stations, learners measure their jump distances, handfuls of "gold," water-soaked sponges, "buffalo chip" throws, arm spans, "stone" throws, "arrow" tosses, foot sizes, pots of beans, and "shooting" distances. This activity works well outside.

  18. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

  19. Agora - Asteroid rendezvous

    Microsoft Academic Search

    A. Balogh

    1984-01-01

    The Asteroid Gravity, Optical, and Radar Analysis probe designated 'Agora' is undergoing feasibility studies at ESA for a mission to the asteroids, in the 1990s, which would survey several targets with an array of instruments. The primary payload of Agora includes wide angle and high resolution cameras, an IR imaging spectrometer, a radar altimeter, a magnetometer, and a gamma-ray spectrometer.

  20. DARe: Dark Asteroid Rendezvous

    NASA Technical Reports Server (NTRS)

    Noll, K. S.; McFadden, L. A.; Rhoden, A. R.; Lim, L. F.; Boynton, W. V.; Carter, L. M.; Collins, G.; Englander, J. A.; Goossens, S. A.; Grundy, W. M.; Li, J.-Y.; Mottola, S.; Oberst, J.; Orosei, R.; Parsons, A. M.; Preusker, F.; Reuter, D. C.; Simon, A. A.; Thomas, C. A.; Walsh, K.; Zolensky, M. E.

    2015-01-01

    Small bodies record the chemical, physical, and dynamical processes that gave birth to and shaped the solar system. The great variety of small bodies reflects the diversity of both their genesis and their histories. The DARe mission conducts a critical test of how small body populations reflect a history of planetary migration and planetesimal scattering. This understanding is crucial for planning future NASA missions and placing current and past missions into context.

  1. Agora - Asteroid rendezvous

    NASA Astrophysics Data System (ADS)

    Balogh, A.

    1984-06-01

    The Asteroid Gravity, Optical, and Radar Analysis probe designated 'Agora' is undergoing feasibility studies at ESA for a mission to the asteroids, in the 1990s, which would survey several targets with an array of instruments. The primary payload of Agora includes wide angle and high resolution cameras, an IR imaging spectrometer, a radar altimeter, a magnetometer, and a gamma-ray spectrometer. The prospective launch vehicle will be an Ariane 44L.

  2. Randomised study on single stage laparo-endoscopic rendezvous (intra-operative ERCP) procedure versus two stage approach (Pre-operative ERCP followed by laparoscopic cholecystectomy) for the management of cholelithiasis with choledocholithiasis

    PubMed Central

    Sahoo, Manash Ranjan; Kumar, Anil T; Patnaik, Aashish

    2014-01-01

    INTRODUCTION: The ‘Rendezvous’ technique consists of laparoscopic cholecystectomy (LC) standards with intra-operative cholangiography followed by endoscopic sphincterotomy. The sphincterotome is driven across the papilla through a guidewire inserted by the transcystic route. In this study, we intended to compare the two methods in a prospective randomised trial. MATERIALS AND METHODS: From 2005 to 2012, we enrolled 83 patients with a diagnosis of cholecysto-choledocolithiasis. They were randomised into two groups. In ‘group-A’,41 patients were treated with two stages management, first by pre-operative endoscopic retrograde cholangiopancreatography (ERCP) and common bile duct (CBD) clearance and second by LC. In ‘group-B’, 42 patients were treated with LC and intra-operative cholangiography; and when diagnosis of choledocholithiasis was confirmed, patients had undergone one stage management of by Laparo-endoscopic Rendezvous technique. RESULTS: In arm-A and arm-B groups, complete CBD clearance was achieved in 29 and 38 patients, respectively. Failure of the treatment in arm-A was 29% and in arm-B was 9.5%. In arm-A, selective CBD cannulation was achieved in 33 cases (80.5%) and in arm-B in 39 cases (93%). In arm-Agroup, post-ERCP hyperamylasia was presented in nine patients (22%) and severe pancreatitis in five patients (12%) versus none of the patients (0%) in arm-B group, respectively. Mean post-operative hospital stay in arm-A and arm-B groups are 10.9 and 6.8 days, respectively. CONCLUSION: One stage laparo-endoscopic rendezvous approach increases selective cannulation of CBD, reduces post-ERCP pancreatitis, reduces days of hospital stay, increases patient's compliance and prevents unnecessary intervention to CBD. PMID:25013330

  3. Tumbling: From Rally Cars to Toast

    ERIC Educational Resources Information Center

    Belloni, Mario; Christian, Wolfgang

    2012-01-01

    The article by Rod Cross describing the translational and rotational motion of the "Launch of a Vehicle from a Ramp" motivated us to create two computer models showing this type of dynamical behavior.

  4. Incidence Rates

    Cancer.gov

    Close Window State Cancer Profiles Quick Reference Guides ? Quick Reference Guides Index Incidence Rates Send to Printer Text description of this image. Site Home Policies Accessibility Viewing Files FOIA Contact Us U.S. Department of Health and Human

  5. Death Rates

    Cancer.gov

    Close Window State Cancer Profiles Quick Reference Guides ? Quick Reference Guides Index Death Rates Send to Printer Text description of this image. Site Home Policies Accessibility Viewing Files FOIA Contact Us U.S. Department of Health and Human Services

  6. Full relaxation matrix analysis of apparent cross-correlated relaxation rates in four-spin systems

    NASA Astrophysics Data System (ADS)

    Vögeli, Beat

    2013-01-01

    Cross-correlated relaxation (CCR) rates are an established tool for the extraction of relative bond orientations in biomolecules in solution. CCR between dipolar interactions in four-spin systems is a particularly well-suited mechanism. In this paper, a simple approach to analyze systematic experimental errors is formulated in a subspace of the complete four-spin Hilbert space. It is shown that, contrary to the common assumption, the secular approximation of the relaxation matrix is marginal for the most prominent spin systems. With the main focus on the model protein GB3 at room temperature, it is shown that the apparent experimental CCR rates have errors between -12% and +4% for molecules with a molecular tumbling time of 3.5 ns. Although depending on the specific pulse sequence used, the following rule-of-thumb can be established: Judged by absolute values, the errors for H?-C?/H?-C?, HN-N/C?-C', HN-N/C?-C? and HN-N/H?-C? CCR rates can safely be neglected. However, errors for HN-N/HN-N and HN-N/H?-C? CCR rates are on the order of 0.1-0.3 s-1 and must be considered. Tabulated correction factors may be used for their extraction. If larger systems are studied, in most cases the errors cannot be neglected anymore. On the other hand, well-calibrated pulses can safely be assumed to be perfect.

  7. Miniature high-resolution laser radar operating at video rates

    NASA Astrophysics Data System (ADS)

    Smithpeter, Colin L.; Nellums, Robert O.; Lebien, Steve M.; Studor, George

    2000-09-01

    We are developing a laser radar to meet the needs of NASA for a 5-lb, 150 in3 image sensor with a pixel range accuracy of 0.1-inch. NASA applications include structural dynamics measurements, navigation guidance in rendezvous and proximity operations, and space vehicle inspection. The sensor is based on the scannerless range imager architecture developed at Sandia. This architecture modulates laser floodlight illumination and a focal plane receiver to phase encode the laser time of flight (TOF) for each pixel. We believe this approach has significant advantages over architectures directly measuring TOF including high data rate, reduced detector bandwidth, and conventional focal plane array (FPA) detection. A limitation of the phase detection technique is its periodic nature, which provides relative range information over a finite ambiguity interval. To extend the operating interval while maintaining a given range resolution, a LADAR sensor using dual modulation frequencies has been developed. The modulation frequency values can be scaled to meet the resolution and range interval requirements of different applications. Results from the miniature NASA sensor illustrate the advantages of the dual-frequency operation and the ability to provide the range images of 640 by 480 pixels at 30 frames per second.

  8. Supplementary Investigation to Determine the Effects of Center-of-Gravity Position on the Spin, Longitudinal-Trim, and Tumbling Characteristics of a 1/20-Scale Model of the Consolidated Vultee 7002 Airplane (Flying Mock-up of XF-92)

    NASA Technical Reports Server (NTRS)

    Klinar, Walter J.; Jones, Ira P., Jr.

    1948-01-01

    A supplementary wind-tunnel investigation has been conducted to determine the effect of rearward positions of the center of gravity on the spin, longitudinal-trim, and tumbling characteristics of the 1/20-scale model of the Consolidated Vultee 7002 airplane equipped with the single vertical tail. A few tests were also made with dual vertical tails added to the model. The model was ballasted to represent, the airplane in its approximate design gross weight for two center-of-gravity positions, 3O and 35 percent of the mean aerodynamic chord. The original tests previously reported were for a center-of-gravity position of 24 percent of the mean aerodynamic chord.

  9. Coding gains and error rates from the Big Viterbi Decoder

    NASA Astrophysics Data System (ADS)

    Onyszchuk, I. M.

    1991-08-01

    A prototype hardware Big Viterbi Decoder (BVD) was completed for an experiment with the Galileo Spacecraft. Searches for new convolutional codes, studies of Viterbi decoder hardware designs and architectures, mathematical formulations, and decompositions of the deBruijn graph into identical and hierarchical subgraphs, and very large scale integration (VLSI) chip design are just a few examples of tasks completed for this project. The BVD bit error rates (BER), measured from hardware and software simulations, are plotted as a function of bit signal to noise ratio E sub b/N sub 0 on the additive white Gaussian noise channel. Using the constraint length 15, rate 1/4, experimental convolutional code for the Galileo mission, the BVD gains 1.5 dB over the NASA standard (7,1/2) Maximum Likelihood Convolution Decoder (MCD) at a BER of 0.005. At this BER, the same gain results when the (255,233) NASA standard Reed-Solomon decoder is used, which yields a word error rate of 2.1 x 10(exp -8) and a BER of 1.4 x 10(exp -9). The (15, 1/6) code to be used by the Cometary Rendezvous Asteroid Flyby (CRAF)/Cassini Missions yields 1.7 dB of coding gain. These gains are measured with respect to symbols input to the BVD and increase with decreasing BER. Also, 8-bit input symbol quantization makes the BVD resistant to demodulated signal-level variations which may cause higher bandwidth than the NASA (7,1/2) code, these gains are offset by about 0.1 dB of expected additional receiver losses. Coding gains of several decibels are possible by compressing all spacecraft data.

  10. Coding gains and error rates from the Big Viterbi Decoder

    NASA Technical Reports Server (NTRS)

    Onyszchuk, I. M.

    1991-01-01

    A prototype hardware Big Viterbi Decoder (BVD) was completed for an experiment with the Galileo Spacecraft. Searches for new convolutional codes, studies of Viterbi decoder hardware designs and architectures, mathematical formulations, and decompositions of the deBruijn graph into identical and hierarchical subgraphs, and very large scale integration (VLSI) chip design are just a few examples of tasks completed for this project. The BVD bit error rates (BER), measured from hardware and software simulations, are plotted as a function of bit signal to noise ratio E sub b/N sub 0 on the additive white Gaussian noise channel. Using the constraint length 15, rate 1/4, experimental convolutional code for the Galileo mission, the BVD gains 1.5 dB over the NASA standard (7,1/2) Maximum Likelihood Convolution Decoder (MCD) at a BER of 0.005. At this BER, the same gain results when the (255,233) NASA standard Reed-Solomon decoder is used, which yields a word error rate of 2.1 x 10(exp -8) and a BER of 1.4 x 10(exp -9). The (15, 1/6) code to be used by the Cometary Rendezvous Asteroid Flyby (CRAF)/Cassini Missions yields 1.7 dB of coding gain. These gains are measured with respect to symbols input to the BVD and increase with decreasing BER. Also, 8-bit input symbol quantization makes the BVD resistant to demodulated signal-level variations which may cause higher bandwidth than the NASA (7,1/2) code, these gains are offset by about 0.1 dB of expected additional receiver losses. Coding gains of several decibels are possible by compressing all spacecraft data.

  11. A Proposed Strategy for the U.S. to Develop and Maintain a Mainstream Capability Suite ("Warehouse") for Automated/Autonomous Rendezvous and Docking in Low Earth Orbit and Beyond

    NASA Technical Reports Server (NTRS)

    Krishnakumar, Kalmanje S.; Stillwater, Ryan A.; Babula, Maria; Moreau, Michael C.; Riedel, J. Ed; Mrozinski, Richard B.; Bradley, Arthur; Bryan, Thomas C.

    2012-01-01

    The ability of space assets to rendezvous and dock/capture/berth is a fundamental enabler for numerous classes of NASA fs missions, and is therefore an essential capability for the future of NASA. Mission classes include: ISS crew rotation, crewed exploration beyond low-Earth-orbit (LEO), on-orbit assembly, ISS cargo supply, crewed satellite servicing, robotic satellite servicing / debris mitigation, robotic sample return, and robotic small body (e.g. near-Earth object, NEO) proximity operations. For a variety of reasons to be described, NASA programs requiring Automated/Autonomous Rendezvous and Docking/Capture/Berthing (AR&D) capabilities are currently spending an order-of-magnitude more than necessary and taking twice as long as necessary to achieve their AR&D capability, "reinventing the wheel" for each program, and have fallen behind all of our foreign counterparts in AR&D technology (especially autonomy) in the process. To ensure future missions' reliability and crew safety (when applicable), to achieve the noted cost and schedule savings by eliminate costs of continually "reinventing the wheel ", the NASA AR&D Community of Practice (CoP) recommends NASA develop an AR&D Warehouse, detailed herein, which does not exist today. The term "warehouse" is used herein to refer to a toolbox or capability suite that has pre-integrated selectable supply-chain hardware and reusable software components that are considered ready-to-fly, low-risk, reliable, versatile, scalable, cost-effective, architecture and destination independent, that can be confidently utilized operationally on human spaceflight and robotic vehicles over a variety of mission classes and design reference missions, especially beyond LEO. The CoP also believes that it is imperative that NASA coordinate and integrate all current and proposed technology development activities into a cohesive cross-Agency strategy to produce and utilize this AR&D warehouse. An initial estimate indicates that if NASA strategically coordinates the development of a robust AR&D capability across the Agency, the cost of implementing AR&D on a spacecraft could be reduced from roughly $70M per mission to as low as $7M per mission, and the associated development time could be reduced from 4 years to 2 years, after the warehouse is completely developed. Table 1 shows the clear long-term benefits to the Agency in term of costs and schedules for various missions. (The methods used to arrive at the Table 1 numbers is presented in Appendices A and B.)

  12. The First Joint Report of the General Thomas P. Stafford Task Force and the Academician Vladimir F. Utkin Advisory Expert Council on the Shuttle-Mir Rendezvous and Docking Missions

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In October 1992, the National Aeronautics and Space Administration (NASA) and the Russian Space Agency (RSA) formally agreed to conduct a fundamentally new program of human cooperation in space. The 'Shuttle-Mir Program' encompassed combined astronaut-cosmonaut activities on the Shuttle, Soyuz Test Module(TM), and Mir station spacecraft. At that time, NASA and RSA limited the project to: the STS-60 mission carrying the first Russian cosmonaut to fly on the U.S. Space Shuttle; the launch of the first U.S. astronaut on the Soyuz vehicle for a multi-month mission as a member of a Mir crew; and the change-out of the U.S.-Russian Mir crews with a Russian crew during a Shuttle rendezvous and docking mission with the Mir Station. The objectives of the Phase 1 Program are to provide the basis for the resolution of engineering and technical problems related to the implementation of the ISS and future U.S.-Russian cooperation in space. This, combined with test data generated during the course of the Shuttle flights to the Mir station and extended joint activities between U.S. astronauts and Russian cosmonauts aboard Mir, is expected to reduce the technical risks associated with the construction and operation of the ISS. Phase 1 will further enhance the ISS by combining space operations and joint space technology demonstrations. Phase 1 also provides early opportunities for extended U.S. scientific and research activities, prior to utilization of the ISS.

  13. A Miniature, High-Resolution Laser Radar Operating at Video Rates

    SciTech Connect

    SMITHPETER,COLIN L.; NELLUMS,ROBERT O.; LEBIEN,STEVEN M.; STUDOR,GEORGE

    2000-06-26

    The authors are developing a laser radar to meet the needs of NASA for a 5-lb, 150 in{sup 3} image sensor with a pixel range accuracy of 0.1-inch. NASA applications include structural dynamics measurements, navigation guidance in rendezvous and proximity operations, and space vehicle inspection. The sensor is based on the scannerless range imager architecture developed at Sandia. This architecture modulates laser floodlight illumination and a focal plane receiver to phase encode the laser time of flight (TOF) for each pixel. They believe this approach has significant advantages over architectures directly measuring TOF including high data rate, reduced detector bandwidth, and conventional FPA detection. A limitation of the phase detection technique is its periodic nature, which provides relative range information over a finite ambiguity interval. To extend the operating interval while maintaining a given range resolution, a LADAR sensor using dual modulation frequencies has been developed. This sensor also extends the relative range information to absolute range by calibrating a gating function on the receiver to the TOF. The modulation frequency values can be scaled to meet the resolution and range interval requirements of different applications. Results from the miniature NASA sensor illustrate the advantages of the dual-frequency operation and the ability to provide the range images of 640 by 480 pixels at 30 frames per second.

  14. Rating Movies and Rating the Raters Who Rate Them.

    PubMed

    Zhou, Hua; Lange, Kenneth

    2009-11-01

    The movie distribution company Netflix has generated considerable buzz in the statistics community by offering a million dollar prize for improvements to its movie rating system. Among the statisticians and computer scientists who have disclosed their techniques, the emphasis has been on machine learning approaches. This article has the modest goal of discussing a simple model for movie rating and other forms of democratic rating. Because the model involves a large number of parameters, it is nontrivial to carry out maximum likelihood estimation. Here we derive a straightforward EM algorithm from the perspective of the more general MM algorithm. The algorithm is capable of finding the global maximum on a likelihood landscape littered with inferior modes. We apply two variants of the model to a dataset from the MovieLens archive and compare their results. Our model identifies quirky raters, redefines the raw rankings, and permits imputation of missing ratings. The model is intended to stimulate discussion and development of better theory rather than to win the prize. It has the added benefit of introducing readers to some of the issues connected with analyzing high-dimensional data. PMID:20802818

  15. Glomerular filtration rate

    MedlinePLUS

    Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates ... Kasiske BL. Laboratory assessment of kidney disease: glomerular filtration rate, urinalysis, and proteinuria. In: Taal MW, Chertow ...

  16. Heart Rate and Exercise

    NSDL National Science Digital Library

    Barbara Z. Tharp

    2009-01-01

    In this activity about heart health (on page 27 of the PDF), learners measure their heart rates after a variety of physical activities and compare the results with their resting heart rates, and with the heart rates of other learners in their groups. Learners also make predictions about their pulse rates. This lesson guide includes background information, setup and management tips, extension ideas, information about the heart in space and a handout.

  17. Miniature high-resolution laser radar operating at video rates

    Microsoft Academic Search

    Colin L. Smithpeter; Robert O. Nellums; STEVEN M. LEBIEN; George Studor

    2000-01-01

    We are developing a laser radar to meet the needs of NASA for a 5-lb, 150 in3 image sensor with a pixel range accuracy of 0.1-inch. NASA applications include structural dynamics measurements, navigation guidance in rendezvous and proximity operations, and space vehicle inspection. The sensor is based on the scannerless range imager architecture developed at Sandia. This architecture modulates laser

  18. The Apollo VHF ranging system

    Microsoft Academic Search

    E. J. Nossen

    1977-01-01

    As the Apollo program proceeded, redundancy became a requirement for all crew safety functions. One critical period of the Apollo missions was the rendezvous of the Command Module and the Lunar Module. The rendezvous radar provided the critical range, range rate, and angle measurements necessary to complete the rendezvous. Use of a redundant radar for backup was out of the

  19. Rate theories for biologists

    PubMed Central

    Zhou, Huan-Xiang

    2012-01-01

    Some of the rate theories that are most useful for modeling biological processes are reviewed. By delving into some of the details and subtleties in the development of the theories, the review will hopefully help the reader gain a more than superficial perspective. Examples are presented to illustrate how rate theories can be used to generate insight at the microscopic level into biomolecular behaviors. Attempt is made to clear up a number of misconceptions in the literature regarding popular rate theories, including the appearance of Planck’s constant in the transition-state theory and the Smoluchowski result as an upper limit for protein-protein and protein-DNA association rate constants. Future work in combining the implementation of rate theories through computer simulations with experimental probes of rate processes, and in modeling effects of intracellular environments so theories can be used for generating rate constants for systems biology studies is particularly exciting. PMID:20691138

  20. Power-aware rendezvous with shrinking footprints

    Microsoft Academic Search

    Hassan Jaleel; Magnus Egerstedt

    2011-01-01

    In this paper we investigate how power consump- tion affects mobility-based coordination algorithms for multi- robot systems by explicitly coupling the control laws to the available power levels. In particular, we will consider a sensor network comprising of mobile sensors which use omni direc- tional RF or radar based antennas for communication, with a disk-shaped communications footprint. As power decrease

  1. Rendezvous and docking with remote piloted vehicles

    Microsoft Academic Search

    J. D. Micheal

    1984-01-01

    The man-in-the-loop control system requirements for the Orbital Maneuvering Vehicle (OMV) are examined. Since many similarities exist between the Teleoperator Retrieval System (TRS) and the unfolding OMV concept, a review of the TRS control system baseline along with selected design trades which led to that baseline are discussed. TRS program issues relevant to the man-in-the-loop control system design include thruster

  2. Shuttle rendezvous radar performance evaluation and simulation

    Microsoft Academic Search

    J. W. Griffin; A. C. Lindberg; T. B. Ahn; P. L. Harton

    1988-01-01

    The US Space Shuttle's Ku-band system was specifically designed for communications and tracking functions which are required during on-orbit operations with other spacecraft. Operating modes permit search and acquisition to be accomplished by computer designation or under manual control by the astronaut. Ku-band system data channels drive on-board dedicated displays and are incorporated into state vector updates by Shuttle guidance

  3. Power-aware rendezvous with shrinking footprints

    Microsoft Academic Search

    Hassan Jaleel; Magnus Egerstedt

    2011-01-01

    In this paper we investigate how power consumption affects mobility-based coordination algorithms for multi-robot systems by explicitly coupling the control laws to the available power levels. In particular, we will consider a sensor network comprising of mobile sensors which use omni directional RF or radar based antennas for communication, with a disk-shaped communications footprint. As power decrease with time, the

  4. Telerobotic rendezvous and docking vision system architecture

    NASA Technical Reports Server (NTRS)

    Gravely, Ben; Myers, Donald; Moody, David

    1992-01-01

    This research program has successfully demonstrated a new target label architecture that allows a microcomputer to determine the position, orientation, and identity of an object. It contains a CAD-like database with specific geometric information about the object for approach, grasping, and docking maneuvers. Successful demonstrations were performed selecting and docking an ORU box with either of two ORU receptacles. Small, but significant differences were seen in the two camera types used in the program, and camera sensitive program elements have been identified. The software has been formatted into a new co-autonomy system which provides various levels of operator interaction and promises to allow effective application of telerobotic systems while code improvements are continuing.

  5. Alan Shepard in the Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut Alan Shepard (right) was one of 14 astronauts, 8 NASA test pilots, and 2 McDonnell test pilots who took part in simulator studies. Shepard flew the simulator on November 14, 1963. A.W. Vogeley wrote: 'Many of the astronauts have flown this simulator in support of the Gemini studies and they, without exception, appreciated the realism of the visual scene. The simulator has also been used in the development of pilot techniques to handle certain jet malfunctions in order that aborts could be avoided. In these situations large attitude changes are sometimes necessary and the false motion cues that were generated due to earth gravity were somewhat objectionable; however, the pilots were readily able to overlook these false motion cues in favor of the visual realism.' Roy F. Brissenden noted that: 'The basic Gemini control studies developed the necessary techniques and demonstrated the ability of human pilots to perform final space docking with the specified Gemini-Agena systems using only visual references. ... Results... showed that trained astronauts can effect the docking with direct acceleration control and even with jet malfunctions as long as good visual conditions exist.... Probably more important than data results was the early confidence that the astronauts themselves gained in their ability to perform the maneuver in the ultimate flight mission.' Shepard commented: 'I had the feeling tonight - a couple of times - that I was actually doing the space mission instead of the simulation. As I said before, I think it is a very good simulation.' Shepard also commented on piloting techniques. Most astronauts arrived at this same preferred technique: Shepard: 'I believe I have developed the preferred technique for these conditions and the technique appeared to me to be best was to come in slightly above the target so that I was able to use the longitudinal marks on the body of the target as a reference, particularly for a lateral translation and, of course, I used the foreshortening effect for a vertical translation, and this appeared to give me the best results. By that I mean the least number of control motions and the lowest fuel usage and the best end techniques, or the best end conditions, I should say.' Engineer: 'When you started to run you didn't start thrusting immediately I don't believe. It looked like you started working on your attitudes, then started closing in.' Shepard: 'That is correct. I did that because I felt that I wanted to get the X-axis translation in the most effective vector and for minimum fuel usage that wouldn't introduce any other lateral or vertical offsets that did not already exist.'

  6. Near Earth Asteroid Rendezvous - A Pictorial Voyage

    NSDL National Science Digital Library

    This site offers students an opportunity to participate in a pictorial voyage that follows the NEAR spacecraft from its inception through the cruise phase to asteroid 433 Eros. They will learn about the rationale for visiting an asteroid, the instruments and construction of the spacecraft, and follow its flyby of the asteroid Mathilde, swingby of Earth, and encounter with Eros.

  7. Mars Researchers Rendezvous on Remote Arctic Island

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Devon Island is situated in an isolated part of Canada's Nunavut Territory, and is usually considered to be the largest uninhabited island in the world. However, each summer since 1999, researchers from NASA's Haughton-Mars Project and the Mars Society reside at this 'polar desert' location to study the geologic and environmental characteristics of a site which is considered to be an excellent 'Mars analog': a terrestrial location wherein specific conditions approximate environmental features reported on Mars. Base camps established amidst the rocks and rubble surrounding the Haughton impact crater enable researchers to conduct surveys designed to test the habitat, equipment and technology that may be deployed during a human mission to Mars. One of the many objectives of the project scientists is to understand the ice formations around the Haughton area, in the hopes that this might ultimately assist with the recognition of areas where ice can be found at shallow depth on Mars.

    These images of Devon Island from NASA's Multi-angle Imaging SpectroRadiometer (MISR) instrument provide contrasting views of the spectral and angular reflectance 'signatures' of different surfaces within the region. The top panel is a natural color view created with data from the red, green and blue-bands of MISR's nadir (vertical-viewing) camera. The bottom panel is a false-color multiangular composite of the same area, utilizing red band data from MISR's 60-degree backward, nadir, and 60-degree forward-viewing cameras, displayed as red, green and blue, respectively. In this representation, colors highlight textural properties of elements within the scene, with blue tones indicating smooth surfaces (which preferentially forward scatter sunlight) and red hues indicating rougher surfaces (which preferentially backscatter). The angular reflectance 'signature' of low clouds causes them to appear purple, and this visualization provides a unique way of distinguishing clouds from snow and ice.

    The data were captured on June 28, 2001, during the early part of the arctic summer, when sea ice becomes thinner and begins to move depending upon localized currents and winds. In winter the entire region is locked with several meters of nearly motionless sea ice, which acts as a thermodynamic barrier to the loss of heat from the comparatively warm ocean to the colder atmosphere. Summer melting of sea ice can be observed at the two large, dark regions of open water; one is present in the Jones Sound (near the top to the left of center), and another appears in the Wellington Channel (left-hand edge). A large crack caused by tidal heaving has broken the ice cover over the Parry Channel (lower right-hand corner). A substantial ice cap permanently occupies the easternmost third of the island (upper right). Surface features such as dendritic meltwater channels incised into the island's surface are apparent. The Haughton-Mars project site is located slightly to the left and above image center, in an area which appears with relatively little surface ice, near the island's inner 'elbow.'

    The images were acquired during Terra orbit 8132 and cover an area of about 334 kilometers x 229 kilometers. They utilize data from blocks 27 to 31 within World Reference System-2 path 42.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  8. 75 FR 44794 - Rendezvous International v.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ...released only upon presentation by Respondents of Original endorsed Negotiable Bills of Lading. The payment terms were on a CAD (Cash Against Documents) basis.'' Complainant alleges that the terms of the Bill of Lading were ``violated by...

  9. Grinding media oscillation: effect on torsional vibrations in tumble mills 

    E-print Network

    Toram, Kiran Kumar

    2005-11-01

    is 1?? (32 mm). Each bearing has the capability to take a 3000 lb (1360 kg) radial and 1000 lb (424 kg) axial load. The mill is connected to the outboard end of the rotor (an overhung load at a distance of 3? (76 mm) from the bearing). The other end... Frequencies?????????42 5.2 Measurements and Predictions for 30% and 40% Fill Volumes???????..48 xii NOMENCLATURE a Overhung load distance from right bearing D Free fall distance e Distance between center of gravity...

  10. Laptops in the Humanities: Classroom Walls Come Tumbling Down

    ERIC Educational Resources Information Center

    Weaver, Barbara E.

    2005-01-01

    This chapter describes successful assignments that made creative use of laptops in writing, literature, and public speaking courses. Some activities moved the session out of the classroom to outdoor locations.

  11. Memory effects in tumbling nematics of 8CB liquid crystals

    E-print Network

    Balaji Yendeti; Ashok Vudaygiri

    2015-05-10

    Particle tracking with a 0.98$\\mu$m silica sphere is used in determining precessional motion of nematic director in nematic phase of 8CB liquid crystals, as it probes those oriented structures which are of the same wavelength as of the sphere size. Velocity auto correlation(VACF) is used in determining those structures in both parallel and perpendicular orientations to the neamatic director. Further, a generic approach by considering the time dependent harmonic oscillator motions is used to analyze the VACF distribution function. This approach leads to observe a transition in the structures of nematic phase that are comparable to transformations from underdamped harmonic oscillator motion to critically damped motion. Also, we measured the microstructural properties and calculated micromechanical properties. The experimental analysis approach used here for 8CB liquid crystals helps to understand and characterize the general dynamic behavior of complex fluids. With this analysis, `dynamics of complex fluids' becomes no more `complex'.

  12. Metabolic rate measurement system

    NASA Technical Reports Server (NTRS)

    Koester, K.; Crosier, W.

    1980-01-01

    The Metabolic Rate Measurement System (MRMS) is an uncomplicated and accurate apparatus for measuring oxygen consumption and carbon dioxide production of a test subject. From this one can determine the subject's metabolic rate for a variety of conditions, such as resting or light exercise. MRMS utilizes an LSI/11-03 microcomputer to monitor and control the experimental apparatus.

  13. Open Rating Systems

    Microsoft Academic Search

    R. Guha

    In the offline world, we look to the people we trust and those they trust for reliable information. In this paper, we present a compu- tational model of this phenomenon and show how it can be used to identify high quality content in an Open Rating System, i.e., a system in which any user can rate content. We present a

  14. Heat release rate calorimetry

    Microsoft Academic Search

    Edwin E. Smith

    1996-01-01

    A simple, theoretically sound method for eliminating the effects of internal heat absorption on rate of heat release is described for the Ohio State University (OSU) Release Rate apparatus. By monitoring the temperature of metal walls and calculating the heat loss to surroundings caused by changes in wall temperature due to heat absorption, a complete energy balance on the system

  15. Controlled Rate Cooling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlled-rate cooling is one of several techniques available for the long-term storage of plants in liquid nitrogen. In this technique samples are slowly cooled to an intermediate temperature and then plunged in liquid nitrogen. Controlled rate cooling is based on osmotic regulation of cell conte...

  16. Mortality Rate, Under-5

    NSDL National Science Digital Library

    World Bank

    Under five mortality data for nearly all countries in the world from 2005-2008. A broader measure of child health than infant mortality, this is the probability of dying before ones fifth birthday given the current rates. Rates in countries vary widely from the world average of 67-per-1000 which is decreasing.

  17. High Redshift Supernova Rates

    E-print Network

    Tomas Dahlen; Louis-Gregory Strolger; Adam G. Riess; Bahram Mobasher; Ranga-Ram Chary; Christopher J. Conselice; Henry C. Ferguson; Andrew S. Fruchter; Mauro Giavalisco; Mario Livio; Piero Madau; Nino Panagia; John L. Tonry

    2004-06-24

    We use a sample of 42 supernovae detected with the Advanced Camera for Surveys on-board the Hubble Space Telescope as part of the Great Observatories Origins Deep Survey to measure the rate of core collapse supernovae to z~0.7 and type Ia supernovae to z~1.6. This significantly increases the redshift range where supernova rates have been estimated from observations. The rate of core collapse supernovae can be used as an independent probe of the cosmic star formation rate. Based on the observations of 17 core collapse supernovae, we measure an increase in the core collapse supernova rate by a factor of 1.6 in the range 0.31 compared to low redshift. At higher redshift (z>1), we find a suggested decrease in the type Ia rate with redshift. This evolution of the Ia rate with redshift is consistent with a type Ia progenitor model where there is a substantial delay between the formation of the progenitor star and the explosion of the supernova. Assuming that the type Ia progenitor stars have initial main sequence masses 3-8 M_Sun, we find that 5-7% of the available progenitors explode as type Ia supernovae.

  18. 5 Year Rate Changes

    Cancer.gov

    Close Window State Cancer Profiles Quick Reference Guides ? Quick Reference Guides Index 5 Year Rate Changes Send to Printer Text description of this image. Site Home Policies Accessibility Viewing Files FOIA Contact Us U.S. Department of Health and

  19. Controlled Rate Cooling

    Microsoft Academic Search

    Barbara M. Reed; Esther Uchendu

    Controlled rate cooling is based on osmotic regulation of cell contents and freeze-induced dehydration. The samples are pretreated\\u000a in cryoprotectant solutions and cooled at a standard rate to an intermediate temperature such as –35°C or –40°C, with ice\\u000a nucleation initiated at about –9°C. At the freezing point of the cryoprotectant solution, ice nucleation is initiated, and\\u000a ice forms in the

  20. Rate Tornado Damage

    NSDL National Science Digital Library

    Lexi Krock

    An interactive Flash animation that educates students about the Fujita scale for rating tornado wind speeds and the damage caused by tornados. After being presented with photographs of tornado damage, students are challenged to assign the tornado a rating on the F-scale. The interactive explains the different levels of the F-scale and provides instant feedback on whether or not the correct category was assigned to the tornado.

  1. Hydration rate of obsidian.

    PubMed

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years. PMID:17782901

  2. Heart Rate Monitors

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Under a NASA grant, Dr. Robert M. Davis and Dr. William M. Portnoy came up with a new type of electrocardiographic electrode that would enable long term use on astronauts. Their invention was an insulated capacitive electrode constructed of a thin dielectric film. NASA subsequently licensed the electrode technology to Richard Charnitski, inventor of the VersaClimber, who founded Heart Rate, Inc., to further develop and manufacture personal heart monitors and to produce exercise machines using the technology for the physical fitness, medical and home markets. Same technology is on both the Home and Institutional Model VersaClimbers. On the Home Model an infrared heart beat transmitter is worn under exercise clothing. Transmitted heart rate is used to control the work intensity on the VersaClimber using the heart rate as the speedometer of the exercise. This offers advantages to a full range of users from the cardiac rehab patient to the high level physical conditioning of elite athletes. The company manufactures and markets five models of the 1*2*3 HEART RATE monitors that are used wherever people exercise to accurately monitor their heart rate. Company is developing a talking heart rate monitor that works with portable headset radios. A version of the heart beat transmitter will be available to the manufacturers of other aerobic exercise machines.

  3. Rates of spontaneous mutation.

    PubMed Central

    Drake, J W; Charlesworth, B; Charlesworth, D; Crow, J F

    1998-01-01

    Rates of spontaneous mutation per genome as measured in the laboratory are remarkably similar within broad groups of organisms but differ strikingly among groups. Mutation rates in RNA viruses, whose genomes contain ca. 10(4) bases, are roughly 1 per genome per replication for lytic viruses and roughly 0.1 per genome per replication for retroviruses and a retrotransposon. Mutation rates in microbes with DNA-based chromosomes are close to 1/300 per genome per replication; in this group, therefore, rates per base pair vary inversely and hugely as genome sizes vary from 6 x 10(3) to 4 x 10(7) bases or base pairs. Mutation rates in higher eukaryotes are roughly 0.1-100 per genome per sexual generation but are currently indistinguishable from 1/300 per cell division per effective genome (which excludes the fraction of the genome in which most mutations are neutral). It is now possible to specify some of the evolutionary forces that shape these diverse mutation rates. PMID:9560386

  4. ResellerRatings.Com

    NSDL National Science Digital Library

    You need a new monitor for your home computer and a company has one for sale really cheap on the 'Net, but you've never heard of them and their Website doesn't exactly inspire confidence. How do you know if they'll give you the deal of a lifetime or just take your money and run? Or (more likely) what if the new monitor does show up but doesn't work? Will you be able to get your money back? It's hard to make a big purchase with doubts like these hanging over your head, but fortunately help is available. As their name implies, ResellerRatings.Com provides ratings of over 1,300 online computer hardware vendors, determined by feedback from people who have purchased products from those vendors. In addition to an overall score, each company's rating is broken down into component totals that evaluate things like how knowledgeable or helpful their salespeople were, whether there were any problems with shipping or delivery, or how well the company dealt with returning or replacing a product. Also available are comments on each company from the customers who contributed to the ratings, so you can get more of a feel for exactly why the scores might be low or high in a given area and, in general, what kind of experience you might have when making your purchase. Overall, ResellerRatings.Com is an invaluable resource for anyone buying computer hardware over the Internet.

  5. Federal Reserve Rate Cuts

    NSDL National Science Digital Library

    Waters, Megan.

    1998-01-01

    This week's In the News chronicles recent Federal Reserve Board decisions to lower interest rates. The eleven resources discussed provide news, opinion, and consumer information on the FRB BOG action. Following the first US interest rate cut in three years on September 29, 1998, FED Chairman Alan Greenspan caught fire from Wall Street. "Traders were disappointed" in the mere quarter point drop, according to Time business reporter Bernard Baumohl, but "Greenspan will have to make do with the gratitude of the rest of the world." Although the DOW initially fell 54 points Tuesday, a second 0.25% cut to short-term interest rates on October 15, 1998 sent stocks soaring 330 points--the third largest one-day point gain in history. Analysts now hope that US investor optimism--coupled with IMF and World Bank action in Brazil, Russia, and Asia--will ease the world-wide economic crises.

  6. Low Bit Rate Channels

    Microsoft Academic Search

    David K. Asano; Ryuji Kohno

    In this paper, intelligent compression techniques to allow transmission of text and image data over low bit rate channels are proposed. For text, a compression technique for English language text is presented. Compression is carried out by deleting characters that are not necessary for comprehension by a human reader. Decompression is carried out on a sentence by sentence basis using

  7. Money and interest rates

    Microsoft Academic Search

    Cyril Monnet; Warren E. Weber

    2001-01-01

    This study describes and reconciles two common, seemingly contradictory views about a key monetary policy relationship: that between money and interest rates. Data since 1960 for about 40 countries support the Fisher equation view, that these variables are positively related. But studies taking expectations into account support the liquidity effect view, that they are negatively related. A simple model incorporates

  8. Average Rate of Change

    NSDL National Science Digital Library

    Roberts, Lila F.

    2005-04-21

    This demo provides students with a concrete understanding of the average rate of change for physical situations and for functions described in tabular or graphic form. Animations in gif and Quicktime format are available, as well as Excel programs for classroom or student use.

  9. Understanding Rates of Change.

    ERIC Educational Resources Information Center

    Weil, Aurelia; Russell, Larry

    This paper presents three activities on how to analyze rates of change in real-life situations using TI-83 calculators and computer-based laboratories. Activities include 24 hour temperature data, the temperature of a light bulb, and an M&M toss. Each section contains descriptions of equipment/materials, data collection, and data analysis. The…

  10. A finite-rate chemistry model for using in-situ gas composition measurements within a cometary diamagnetic cavity as a remote sensing tool for studying volatile materials on the nucleus surface

    NASA Astrophysics Data System (ADS)

    Dhooghe, Frederik; De Keyser, Johan; Gunnel, Herbert; Maggiolo, Romain

    2014-05-01

    If everything goes according to plan, Rosetta will rendez-vous with comet 67P/Churyumov-Gerasimenko in May 2014 and will, among other objectives, study the physicochemical evolution of the cometary coma from onset of activity at large solar distances through perihelion at 1.2 AU. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) allows the determination of both neutrals and positive ions in the coma. In situ gas density and composition measurements within the diamagnetic cavity at a certain distance from the nucleus can be used to obtain estimates of particle densities throughout the cavity, as well as give an estimate of the outgassing rates and volatile material composition at the nucleus surface. This is an inverse problem that has been implemented using a finite-rate chemistry model. It requires knowledge of the solar UV flux, the outgassing flow field, and the chemical reactions that transform the neutral gas as it expands outward (e.g. photo-ionization). In this way, in situ measurements in the coma can be used as a remote sensing tool for studying nucleus surface composition. This will be compared to the "ground truth" provided by the instruments on the Philae lander. This contribution will explain the finite-rate chemistry model used and illustrate the data inversion technique. Attention is paid to the opportunities and limitations of the proposed technique.

  11. Rates of Chemical Weathering

    NSDL National Science Digital Library

    Michael Passow

    In this activity, students will investigate the weathering of rocks by chemical processes. They will use effervescent cleansing tablets as a model for rock, and vary surface area, temperature, and acidity to see how rapidly the "rock" dissolves. This investigation will help them understand three of the factors that affect the rate of chemical weathering and develop better understanding of how to design controlled experiments by exploring only one experimental variable at a time.

  12. Rotational rate sensor

    DOEpatents

    Hunter, Steven L. (Livermore, CA)

    2002-01-01

    A rate sensor for angular/rotational acceleration includes a housing defining a fluid cavity essentially completely filled with an electrolyte fluid. Within the housing, such as a toroid, ions in the fluid are swept during movement from an excitation electrode toward one of two output electrodes to provide a signal for directional rotation. One or more ground electrodes within the housing serve to neutralize ions, thus preventing any effect at the other output electrode.

  13. Rate Tornado Damage

    NSDL National Science Digital Library

    Tornadoes can produce damage that ranges from broken tree limbs to a block of houses swept from their foundations. They can inflict utter devastation across a wide swath of land or, destroy one house and leave others on either side largely untouched. In this interactive feature from NOVA Online, sudents examine a series of photos of tornado damage and assign intensity ratings (on the Fulita scale) based on what they see.

  14. The Effects of Specific Respiratory Rates on Heart Rate and Heart Rate Variability

    Microsoft Academic Search

    Hye-Sue Song; Paul M. Lehrer

    2003-01-01

    In this study respiratory rates of 3, 4, 6, 8, 10, 12, and 14 breaths per minute were employed to investigate the effects of these rates on heart rate variability (HRV). Data were collected 16 times at each respiratory rate on 3 female volunteers, and 12 times on 2 female volunteers. Although mean heart rates did not differ among these

  15. Six-Year Graduation Rate 62% Graduation Rates by

    E-print Network

    New Hampshire, University of

    Entering Fall One Year Retention 2011 75% Fall 2006 Six-Year Graduation Rate 62% Graduation Rates by Gender: Female 50% Male 73% Graduation Rates by Ethnicity: Native Amer./Alaskan NA Asian/Pacific NA Black, non-hispanic NA Hispanic 100% White 58% Non-Resident Alien 0% Unknown 50% Graduation Rates

  16. Heart-Rate and Breath-Rate Monitor

    NASA Technical Reports Server (NTRS)

    Cooper, T. G.

    1983-01-01

    Circuit requiring only four integrated circuits (IC's) measures both heart rate and breath rate. Phase-locked loops lock on heart-rate and respiration-rate input signals. Each loop IC contains two phase comparators. Positive-edge-triggered circuit used in making monitors insensitive to dutycycle variations.

  17. Target Heart Rate

    NSDL National Science Digital Library

    Mr. Peterson

    2011-09-18

    Students will practice how to calculate their Target Heart Rate to use during exercise routines. This will help students monitor the intensity of their workouts, and ultimately help them achieve results from their workout. Standard 2: Objective 2: a,b,c Before we discuss what the Target Heart Range is and how we can us it, we must first have some basic knowledge of the heart and it's functions. Click the "habits of the heart" to learn the basics of the heart and how it circulates blood throughout the body. Habits of the Heart The hearts ...

  18. Publishing anonymous survey rating data

    Microsoft Academic Search

    Xiaoxun Sun; Hua Wang; Jiuyong Li; Jian Pei

    2011-01-01

    We study the challenges of protecting privacy of individuals in the large public survey rating data in this paper. Recent\\u000a study shows that personal information in supposedly anonymous movie rating records are de-identified. The survey rating data\\u000a usually contains both ratings of sensitive and non-sensitive issues. The ratings of sensitive issues involve personal privacy.\\u000a Even though the survey participants do

  19. Rate & Detection Rate by Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Cancer Rate (per 1,000 examinations) and Cancer Detection Rate (per 1,000 examinations) for 3,884,059

  20. Rate & Detection Rate Age & Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Cancer Rate (per 1,000 examinations) and Cancer Detection Rate (per 1,000 examinations) for 3,884,059

  1. National Utility Rate Database: Preprint

    SciTech Connect

    Ong, S.; McKeel, R.

    2012-08-01

    When modeling solar energy technologies and other distributed energy systems, using high-quality expansive electricity rates is essential. The National Renewable Energy Laboratory (NREL) developed a utility rate platform for entering, storing, updating, and accessing a large collection of utility rates from around the United States. This utility rate platform lives on the Open Energy Information (OpenEI) website, OpenEI.org, allowing the data to be programmatically accessed from a web browser, using an application programming interface (API). The semantic-based utility rate platform currently has record of 1,885 utility rates and covers over 85% of the electricity consumption in the United States.

  2. Interest Rate Transmission to Commercial Credit Rates in Austria

    Microsoft Academic Search

    Johann Burgstaller; Johannes Kepler

    2003-01-01

    The transmission process from policy-controlled interest rates to bank lending rates deserves reconsideration owing to the implementation of the European Monetary Union (EMU) in 1999. Additional attention to the subject in Austria is due to several large banks which, in 2002, have been charged for not passing on interest rate decreases to their customers. I examine dynamic responses of commercial

  3. Propandiol vapor nucleation rates

    NASA Astrophysics Data System (ADS)

    Anisimov, M. P.; Nasibulin, A. G.; Timoshina, L. V.; Koropchak, J. A.

    2000-08-01

    Consideration of vapor-gas nucleation as binary vapor nucleation (instead widely used the one component approximation for nucleation of this system now) may lead the progress in the development of nucleation theory. Observations of phase transitions initiated by the carrier gas in the critical embryos of condensate can be a sufficiently convincing argument in this discussion. In order to confirm the role of the carrier gases received in the recent research1, in present study 1,2-propanediol and 1,3-propanediol vapor nucleation rates were measured. Carbon dioxide (Tc=304.2 K,Pc=7.39 MPa) and sulfur hexafluoride (Tc=318.7 K,Pc=3.75 MPa) were chosen as the carrier gases, because of their low and convenient critical temperatures, Tc, and critical pressures, Pc. Analysis of the experimental data shows that gas-carrier molecules are involved in new phase embryo formation. Vapor nucleation of investigated substances in a carrier gas atmosphere can be considered as nucleation of binary system.

  4. Rates of Earth degassing

    NASA Technical Reports Server (NTRS)

    Onions, R. K.

    1994-01-01

    The degassing of the Earth during accretion is constrained by Pu-U-I-Xe systematics. Degassing was much more efficient during the first 100-200 Ma than subsequently, and it was more complete for Xe than for the lighter gases. More than 90 percent of the degassed Xe escaped from the atmosphere during this period. The combination of fractional degassing of melts and rare gas escape from the atmosphere is able to explain the deficit of terrestrial Xe as a simple consequence of this early degassing history. By the time Xe was quantitatively retained in the atmosphere, the abundances of Kr and the lighter gases in the Earth's interior were similar to or higher than the present-day atmospheric abundances. Subsequent transfer of these lighter rare gases into the atmosphere requires a high rate of post-accretion degassing and melt production. Considerations of Pu-U-Xe systematics suggest that relatively rapid post-accretion degassing was continued to ca. 4.1-4.2 Ga. The present-day degassing history of the Earth is investigated through consideration of rare gas isotope abundances. Although the Earth is a highly degassed body, depleted in rare gases by many orders of magnitude relative to their solar abundances, it is at the present-day losing primordial rare gases which were trapped at the time of accretion.

  5. The Current Martian Cratering Rate

    NASA Astrophysics Data System (ADS)

    Daubar, I. J.; McEwen, A. S.; Byrne, S.; Dundas, C. M.; Kennedy, M.; Ivanov, B. A.

    2010-03-01

    MRO has now confirmed 100 new primary martian impact sites. We describe the detection rate, estimate global impact rates, analyze seasonal trends, and compare the size-frequency distribution to model isochrons.

  6. Rate accuracy in handwheel cranking

    Microsoft Academic Search

    Robert S. Lincoln

    1954-01-01

    15 Ss cranked a handwheel, in a clockwise direction, at each of 5 rates of speed combined with each of 3 different handwheel radii; another 15 Ss cranked the same rate-radii; combinations counter-clockwise. The Ss were required to achieve the required rate by maintaining alignment between a target and indicator. At lower handwheel speeds, rate-accuracy improved with increases in the

  7. Determinants of heart rate variability

    Microsoft Academic Search

    Hisako Tsuji; Ferdinand J. Venditti; Emily S. Manders; Jane C. Evans; Martin G. Larson; Charles L. Feldman; Daniel Levy

    1996-01-01

    Objectives. This study sought to examine clinical determinants of heart rate variability and to report normative reference values for eight heart rate variability measures.Background. Although the clinical implications of heart rate variability have been described, clinical determinants and normative values of heart rate variability measures have not been studied systematically in a large community-based population.Methods. The first 2 h of

  8. Car Depreciation (rate and slope)

    NSDL National Science Digital Library

    2010-01-01

    The purpose of this activity is for students to use the concept of the rate of depreciation in a real world situation to investigate the relationship between rate and slope. Students create ordered pairs, graph depreciating car values, and calculate rates of depreciation, then identify that the rate of depreciation = slope of the line. Using the equation they then solve for future values and times.

  9. Mirage of Floating Exchange Rates

    Microsoft Academic Search

    Carmen M. Reinhart

    2000-01-01

    This note summarizes some of the highlights of my longer paper with Guillermo Calvo”Fear of Floating.” Many emerging market countries have suffered financial crises. One view blames soft pegs for these crises. Adherents to that view suggest that countries move to corner solutions--hard pegs or floating exchange rates. We analyze the behavior of exchange rates, reserves, and interest rates to

  10. AGRICULTURAL EXCHANGE RATE DATA SHEET

    EPA Science Inventory

    The ERS data set contains annual and monthly data for exchange rates important to U.S. agriculture. It includes both nominal and real exchange rates for 80 countries (plus the European Union) as well as real trade-weighted exchange rate indexes for many commodities and aggregatio...

  11. MEMS Rate Sensors for Space

    NASA Technical Reports Server (NTRS)

    Gambino, Joel P.

    1999-01-01

    Micromachined Electro Mechanical System Rate sensors offer many advantages that make them attractive for space use. They are smaller, consume less power, and cost less than the systems currently available. MEMS Rate Sensors however, have not been optimized for use on spacecraft. This paper describes an approach to developing MEMS Rate Sensors systems for space use.

  12. Catch Curves and Mortality Rates

    Microsoft Academic Search

    D. S. Robson; D. G. Chapman

    1961-01-01

    The assumptions necessary to obtain a valid estimate of survival rate from a single catch curve are discussed. An example of the best estimate of survival rate and its variance is worked out for the case that age is known exactly for the entire sample. A test for validity of the model is illustrated. Methods of estimating the survival rate

  13. Hummingbirds as net rate maximisers

    Microsoft Academic Search

    Alasdair I. Houston; David C. Krakauer

    1993-01-01

    The behaviour of foraging hummingbirds can be accounted for by assuming the maximisation of net rate. The currency, net energy per unit volume consumed suggested by Montgomerie et al. (1984), is shown to be an unnecessary means of interpreting behaviour when compared alongside an extended net rate model. The reason for the failure of previous net rate models to account

  14. The Inverted Block Rate:The Inverted Block Rate: An Alternative to Flat Rate BillingAn Alternative to Flat Rate Billing

    E-print Network

    Hughes, Larry

    The Inverted Block Rate:The Inverted Block Rate: An Alternative to Flat Rate BillingAn Alternative;Inverted Block RateInverted Block Rate 22 IntroductionIntroduction ·· Modern societies rely on electrical collectionMetering and Rate Models facilitate collection #12;Inverted Block RateInverted Block Rate 33 Rate

  15. Discharge ratings at gaging stations

    USGS Publications Warehouse

    Kennedy, E.J.

    1984-01-01

    A discharge rating is the relation of the discharge at a gaging station to stage and sometimes also to other variables. This chapter of 'Techniques of Water-Resources Investigations' describes the procedures commonly used to develop simple ratings where discharge is related only to stage and the most frequently encountered types of complex ratings where additional factors such as rate of change in stage, water-surface slope, or index velocity are used. Fundamental techniques of logarithmic plotting and the applications of simple storage routing to rating development are demonstrated. Computer applications, especially for handheld programmable calculators, and data handling are stressed.

  16. Advancing Lidar Sensors Technologies for Next Generation Landing Missions

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Hines, Glenn D.; Roback, Vincent E.; Petway, Larry B.; Barnes, Bruce W.; Brewster, Paul F.; Pierrottet, Diego F.; Bulyshev, Alexander

    2015-01-01

    Missions to solar systems bodies must meet increasingly ambitious objectives requiring highly reliable "precision landing", and "hazard avoidance" capabilities. Robotic missions to the Moon and Mars demand landing at pre-designated sites of high scientific value near hazardous terrain features, such as escarpments, craters, slopes, and rocks. Missions aimed at paving the path for colonization of the Moon and human landing on Mars need to execute onboard hazard detection and precision maneuvering to ensure safe landing near previously deployed assets. Asteroid missions require precision rendezvous, identification of the landing or sampling site location, and navigation to the highly dynamic object that may be tumbling at a fast rate. To meet these needs, NASA Langley Research Center (LaRC) has developed a set of advanced lidar sensors under the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project. These lidar sensors can provide precision measurement of vehicle relative proximity, velocity, and orientation, and high resolution elevation maps of the surface during the descent to the targeted body. Recent flights onboard Morpheus free-flyer vehicle have demonstrated the viability of ALHAT lidar sensors for future landing missions to solar system bodies.

  17. Saturn component failure rate and failure rate modifiers

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Failure mode frequency ratios, environmental adjustment factors, and failure rates for mechanical and electromechanical component families are presented. The failure rates and failure rate modifiers resulted from a series of studies whose purpose was to provide design, tests, reliability, and systems engineers with accurate, up-to-date failure rate information. The results of the studies were achieved through an extensive engineering analysis of the Saturn Program test data and Unsatisfactory Condition Reports (UCR's) and the application of mathematical techniques developed for the studies.

  18. 47 CFR 64.1801 - Geographic rate averaging and rate integration.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Geographic rate averaging and rate integration. 64.1801 Section 64.1801... Geographic Rate Averaging and Rate Integration § 64.1801 Geographic rate averaging and rate integration. (a) The rates charged...

  19. Fed to Raise Interest Rates

    NSDL National Science Digital Library

    Missner, Emily D.

    As expected, the Federal Reserve voted to raise interest rates 0.25 percent, the fifth rate raise since June. The interest rate boost is expected to help keep inflation in check during this record period (108 months) of economic expansion. Technology companies have continued to signal healthy economic growth, and unemployment rates remain low. Despite drastic price hikes in gasoline and heating oil prices, consumers are still spending. This worries economists who watched consumers pay little heed to the last four interest rate increases. The quarter point interest rate increase will average out to an extra $1 a month on consumers's credit cards, which in this period of prosperity, will not curb consumers's spending.

  20. Reproductive rates in schizophrenic outpatients.

    PubMed

    Nanko, S; Moridaira, J

    1993-06-01

    We investigated the marriage rates, the reproductive rates and the marital reproductivity of schizophrenic outpatients in Japan. A total of 553 patients with DSM-III-R-diagnosed schizophrenia at the Teikyo University Hospital, Tokyo, Japan were compared with age- and sex-matched outpatients at surgical clinics of the same hospital. Our findings indicate that the reproductivity of schizophrenics is reduced, even though the sample consists of outpatient population and modern operational diagnostic criteria have been used. The marriage rate and reproductive rate of the schizophrenics were reduced, especially in men. The number of married men was significantly less than that of married women and the reduced marital reproductivity was found in women but not men. These findings indicate that the reduced reproductivity of men in accounted for largely by a reduced rate of marriage, and that in women is accounted for partly by lower rate of reproductivity within marriage. PMID:8356891

  1. 5-Year Rate Changes Graph

    Cancer.gov

    This graph provides a quick look at which cancer sites have rising rates and which have falling rates over the most recent 5 years of data. The goal is for every cancer site to have falling mortality. Incidence is a more complex story that requires local knowledge and interpretation. For example, a successful screening program will result in a short term rise in incidence. The Historical Trends graph can be used to look at the trends in rates.

  2. Incidence rates in dynamic populations

    PubMed Central

    Vandenbroucke, Jan P; Pearce, Neil

    2012-01-01

    The purpose of the present article is to explain the calculation of incidence rates in dynamic populations with the use of simple mathematical and statistical concepts. The first part will consider incidence rates in dynamic populations, and how they can best be taught in basic, intermediate and advanced courses. The second part will briefly explain how and why incidence rates are calculated in cohorts. PMID:23045207

  3. A new silicon rate gyroscope

    Microsoft Academic Search

    W. Geiger; B. Folkmer; J. Merz; H. Sandmaier; W. Lang

    1998-01-01

    HSG-IMIT is developing a new silicon rate gyroscope of very small size, low cost, and high performance. The device is called MARS-RR, which means micromachined angular rate sensor with two rotary oscillation modes. First prototypes, MARS-RRI yielded random walk and bias stability as low as 0.27 deg\\/?h and 65 deg\\/h, respectively. The noise equivalent rate (3 ?) corresponds to a

  4. Circadian rate variation in rate-adaptive pacing systems.

    PubMed

    Lee, M T; Baker, R

    1990-12-01

    By mimicking the natural rate slowdown during sleep, a pacing system can enhance patient comfort while improving device longevity. A new family of rate-adaptive pacemakers accomplishes this circadian rate variation by modeling the patient's sleep-wake cycle using a time-of-day clock inside the device. Furthermore, to account for minor variations in the patient's sleep-wake cycle, sensor data can be used to automatically adapt the starting and stopping points of this change in rate. Using the model, the device begins to gradually reduce the pacing rate beginning one-half hour before the selected bed time. Similarly, the rate begins to increase one-half hour before the selected waking time. Sensor data indicating the presence or absence of patient activity are used to adapt the selected bed and wake times, enabling the system to maintain an appropriate schedule despite changes in the patient's actual schedule. The model approximates natural human adaptation times for time zone or work shift changes. This circadian rate adaptation does not preclude the system's rate response to patient activity; even during sleep time the response to moderate or heavy exercise is essentially unchanged. PMID:1704544

  5. Conducting Market Rate Surveys and Establishing Rate Policies.

    ERIC Educational Resources Information Center

    Karolak, Eric; Collins, Ray; Stoney, Louise

    Market rate surveys and the rate-setting policies and reimbursement rules informed by them are at the core of the market-based approach to child care and are central to the delicate balancing act of ensuring access to subsidized care while at the same time promoting the quality of child care. This report provides an overview of the market-based…

  6. 7 CFR 1779.33 - Interest rates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...and the borrower. They may be either fixed or variable rates. Interest rates will be those rates...subject to Agency review and approval. (b) Variable rate publication. A variable interest rate must be tied to a base...

  7. 7 CFR 3575.33 - Interest rates.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...the borrower. They may be either fixed or variable rates. Interest rates will be those rates...subject to Agency review and approval. (b) Variable rate publication. A variable interest rate must be tied to a base...

  8. Basalt Weathering Rates Across Scales

    NASA Astrophysics Data System (ADS)

    Navarresitchler, A.; Brantley, S.

    2006-12-01

    Weathering of silicate minerals is a known sink for atmospheric CO2. An estimated 30%-35% of the consumption of CO2 from continental silicate weathering can be attributed to basalt weathering (Dessert et al., 2003). To assess basalt weathering rates we examine weathering advance rates of basalt (w, mm/yr) reported at four scales: denudation rates from basalt watersheds (tens of kilometers), rates of soil formation from soil profiles developed on basaltic parent material of known age (meters), rates of weathering rind formation on basalt clasts (centimeters), and laboratory dissolution rates (millimeters). Basalt weathering advance rates calculated for watersheds range between 0.36 and 9.8x10-3 mm/yr. The weathering advance rate for a basalt soil profile in Hawaii is 8.0x10-3 mm/yr while advance rates for clasts range from 5.6x10-6 to 2.4x10-4 mm/yr. Batch and mixed flow laboratory experiments performed at circum- neutral pH yield advance rates of 2.5x10^{-5} to 3.4x10-7 mm/yr when normalized to BET surface area. These results show increasing advance rates with both increasing scale (from laboratory to watersheds) and increasing temperature. If we assume that basalt weathers at an intrinsic rate that applies to all scales then we conclude that variations in weathering advance rates arise from variations in surface area measurement at different scales (D); therefore, basalt weathering is a fractal system. We measure a fractal dimension (dr) of basalt weathering of 2.2. For Euclidean geometries, measured surface area does not vary with the scale at which it is measured and dr equals 2. For natural surfaces, surface area is related to the scale at which it is measured. As scale increases, the minimum size of the surface irregularities that are measurable also increases. The ratio between BET and geometric normalized laboratory dissolution rates has been defined as a roughness parameter, ?, which ranges from ~10-100. We extend the definition of this roughness parameter to compare weathering advance rates at varying scales. Given that, w=10^{-3.7}D^{0.23} we can use the fractal dimension of basalt weathering to define the roughness factor for basalt weathering as, ?=wD1/wD2=(D1/D2)^{0.23}.

  9. Exchange Rate Regimes: Middling Through

    Microsoft Academic Search

    Ashima Goyal

    2006-01-01

    The appropriate exchange rate regime, in the context of integration of currency markets with financial markets and of large international capital flows, continues to be a policy dilemma. It is found that the majority of countries are moving towards somewhat higher exchange and lower interest rate volatility. Features of foreign exchange (forex) markets could be partly motivating these choices. A

  10. Regulation of Human Heart Rate

    NSDL National Science Digital Library

    Ingrid Waldron

    Students learn how to measure heart rate accurately. Then students design and carry out an experiment to test the effects of an activity or stimulus on heart rate, analyze and interpret the data, and present their experiments in a poster session. In this activity students learn about both cardiac physiology and experimental method.

  11. Dual rate pressure relief valve

    NASA Technical Reports Server (NTRS)

    Steeneken, J.

    1968-01-01

    Pressure relief valve vents at a slow bleed rate at one pressure level and at a higher bleed rate at a higher pressure level. The value housing contains a sleeve, inlet port, outlet port, an orifice, a ball and seat arrangement, and a belleville spring diaphragm.

  12. Swap Rates and Credit Quality

    Microsoft Academic Search

    Darrell Duffie; Ming Huang

    1996-01-01

    This article presents a model for valuing claims subject to default by both contracting parties, such as swaps and forwards. With counterparties of different default risk, the promised cash flows of a swap are discounted by a switching discount rate that, at any given state and time, is equal to the discount rate of the counterparty for whom the swap

  13. Defining, Describing and Calculating Rate

    NSDL National Science Digital Library

    Thirteen WNET

    2008-01-01

    This lesson plan grows from two Cyberchase video segments, both on the meaning of speed, to classwork on graphing rate on the coordinate plane. The definitions of speed and rate are set within the grasp of middle school students through this multimedia treatment. Besides a lesson guide, student handouts and assessments with answer keys are included.

  14. The rating of photovoltaic performance

    Microsoft Academic Search

    Keith Emery

    1999-01-01

    The electrical performance of photovoltaic (PV) cells, modules, and systems are rated in terms of their maximum electrical power with respect to a total irradiance, temperature, and spectral irradiance. The impact of the reference conditions, measurement procedures, and equipment on the performance rating is discussed

  15. Behavior Rates of Exceptional Children.

    ERIC Educational Resources Information Center

    Duncan, Ann Dell

    The paper discusses the effects of labels on exceptional children and the benefits of tracking individual or class behaviors instead of mere labels. To determine the sensitivity of behavior rate of planning remedial action, 97 children (mentally retarded, emotionally disturbed, regular, learning disabled, and brain damaged) were rated on five…

  16. Toronto bicycle commuter safety rates.

    PubMed

    Aultman-Hall, L; Kaltenecker, M G

    1999-11-01

    This analysis uses data from a survey of Toronto commuter cyclists that collected information regarding accident history as well as regular commute route to work or school. By relating the route information of the 1196 respondents to facility attributes in a Geographic Information System (GIS), defensible estimates of travel exposure on roads, off-road paths and sidewalks were developed. The rate of collision on off-road paths and sidewalks was lower than for roads. The relative rates for falls and injuries suggest these events are least common on-road followed by off-road paths, and finally most common on sidewalks. The rate of major injuries, an injury that required medical attention, was greatest on sidewalks and the difference between paths and sidewalks was negligible. These rates suggest a need for detailed analysis of sidewalk and off-road path bicycle safety. The absolute event rates per bicycle kilometer were found to be between 26 and 68 times higher than similar rates for automobile travel, re-confirming the urgent bicycle safety crisis. Examination of rates for sub-groups of cyclists suggest that experience is an important factor in bicycle safety. The same survey conducted in Ottawa, Canada found event rates much lower than Toronto. This result may confirm urban form, traffic levels and attitude do affect bicycle safety. The analysis also demonstrates a successful method to quantify bicycle travel exposure information and should be considered for further use as complement to other existing techniques. PMID:10487343

  17. RECYCLING RATE STUDY Prepared by

    E-print Network

    Laughlin, Robert B.

    NATIONAL RECYCLING RATE STUDY Prepared by: Smith, Bucklin and Associates, Inc. Market Research and Statistics Division Chicago, Illinois July 2003 PRINTED ON RECYCLED PAPER #12;BCI RECYCLING RATE STUDY TABLE ....................................................................................................1 II. METHODOLOGY A. Total Pounds of Lead Recycled from Batteries

  18. Towards Smart Grid Dynamic Ratings

    NASA Astrophysics Data System (ADS)

    Cheema, Jamal; Clark, Adrian; Kilimnik, Justin; Pavlovski, Chris; Redman, David; Vu, Maria

    2011-08-01

    The energy distribution industry is giving greater attention to smart grid solutions as a means for increasing the capabilities, efficiency and reliability of the electrical power network. The smart grid makes use of intelligent monitoring and control devices throughout the distribution network to report on electrical properties such as voltage, current and power, as well as raising network alarms and events. A further aspect of the smart grid embodies the dynamic rating of electrical assets of the network. This fundamentally involves a rating of the load current capacity of electrical assets including feeders, transformers and switches. The mainstream approach to rate assets is to apply the vendor plate rating, which often under utilizes assets, or in some cases over utilizes when environmental conditions reduce the effective rated capacity, potentially reducing lifetime. Using active intelligence we have developed a rating system that rates assets in real time based upon several events. This allows for a far more efficient and reliable electrical grid that is able to extend further the life and reliability of the electrical network. In this paper we describe our architecture, the observations made during development and live deployment of the solution into operation. We also illustrate how this solution blends with the smart grid by proposing a dynamic rating system for the smart grid.

  19. Value of IDEA Ratings Questioned

    ERIC Educational Resources Information Center

    Samuels, Christina A.

    2010-01-01

    Just as it has every June since 2006, the U.S. Department of Education last month delivered a rating to each state and territory based on the performance of its special education programs. The ratings, intended to fulfill the Individuals with Disabilities Education Act's requirement that "measurable" and "rigorous" targets be met on the 6.7…

  20. Rate/Trend Comparison Table

    Cancer.gov

    Compares cancer rate changes between a county of a state and the entire state or between a state and the US. The graphic version of this table groups the data so you can see quickly if the trends are rising, falling, or remaining stable and how they compare to the selected comparison rates.

  1. Matching and Conditioned Reinforcement Rate

    ERIC Educational Resources Information Center

    Shahan, Timothy A.; Podlesnik, Christopher A.; Jimenez-Gomez, Corina

    2006-01-01

    Attempts to examine the effects of variations in relative conditioned reinforcement rate on choice have been confounded by changes in rates of primary reinforcement or changes in the value of the conditioned reinforcer. To avoid these problems, this experiment used concurrent observing responses to examine sensitivity of choice to relative…

  2. Innovative Rates Program. Final report

    SciTech Connect

    Not Available

    1982-06-21

    Title II of the Energy Conservation and Production Act (ECPA) as amended by the Public Utility Regulatory Policies Act (PURPA) provided financial assistance to state utility regulatory commissions, nonregulated electric utilities, and the Tennessee Valley Authority through the Innovative Rates Program. The financial assistance was to be used to plan or carry out electric utility regulatory rate reform initiatives relating to innovative rate structures that encourage conservation of energy, electric utility efficiency and reduced costs, and equitable rates to consumers. The Federal and local objectives of the project are described. Activities planned and accomplishments are summarized for the following: project management, data collection, utility bill evaluation, billing enclosure/mailing evaluation, media program evaluation, display evaluation, rate study sessions evaluation, speakers bureau evaluation, and individual customer contacts. A timetable/milestone chart and financial information are included. (MHR)

  3. High Rate Digital Demodulator ASIC

    NASA Technical Reports Server (NTRS)

    Ghuman, Parminder; Sheikh, Salman; Koubek, Steve; Hoy, Scott; Gray, Andrew

    1998-01-01

    The architecture of High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation in other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA's Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an over-view of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

  4. How is entropy production rate related to chemical reaction rate?

    E-print Network

    Banerjee, Kinshuk

    2013-01-01

    The entropy production rate is a key quantity in irreversible thermodynamics. In this work, we concentrate on the realization of entropy production rate in chemical reaction systems in terms of the experimentally measurable reaction rate. Both triangular and linear networks have been studied. They attain either thermodynamic equilibrium or a non-equilibrium steady state, under suitable external constraints. We have shown that the entropy production rate is proportional to the square of the reaction velocity only around equilibrium and not any arbitrary non-equilibrium steady state. This feature can act as a guide in revealing the nature of a steady state, very much like the minimum entropy production principle. A discussion on this point has also been presented.

  5. Interviewer's ratings of personality: can these ratings predict job performance? 

    E-print Network

    Archuleta, Kathryn Diane

    1998-01-01

    The link between personality and job performance has usually been studied using self-report personality data. The present study looked at whether an interviewer's ratings of an applicant's personality can predict future ...

  6. The Average of Rates and the Average Rate.

    ERIC Educational Resources Information Center

    Lindstrom, Peter

    1988-01-01

    Defines arithmetic, harmonic, and weighted harmonic means, and discusses their properties. Describes the application of these properties in problems involving fuel economy estimates and average rates of motion. Gives example problems and solutions. (CW)

  7. The Airline Quality Rating 2004

    NASA Technical Reports Server (NTRS)

    Bowen, Brent D.; Headley, Dean E.

    2004-01-01

    The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline quality on combined multiple performance criteria. This current report, the Airline Quality Rating 2004, reflects monthly Airline Quality Rating scores for 2003. AQR scores far the calendar year 2003 are based on 15 elemnts in four major areas that focus on airline performance aspects important to air travel consumers. The Airline Quality Rating 2004 is a summary of month-by-month quality ratings for U.S. airlines that have at least 1% of domestic passenger volume during 2003. Using the Airline Quality Rating system of weighted averages and monthly performance data in the areas of on-time arrivals, involuntary denied boardings, mishandled baggage, and a combination of 12 customer complaint categories, airlines comparative performance for the calendar year of 2003 is reported. This research monograph contains a brief summary of the AQR methodology, detailed data and charts that track comparative quality for domestic airline operations for the 12-month period of 2003, and industry results. Also, comparative Airline Quality Rating data for 2002 are included, where available, to provide historical perspective

  8. The Airline Quality Rating 2002

    NASA Technical Reports Server (NTRS)

    Bowen, Brent D.; Headley, Dean E.

    2002-01-01

    The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline quality on combined multiple performance criteria. This current report, Airline Quality Rating 2002, reflects monthly Airline Quality Rating scores for 2001. AQR scores for the calendar year 2001 are based on 15 elements that focus on airline performance areas important to air travel consumers. The Airline Quality Rating 2002 is a summary of month-by-month quality ratings for the 11 largest U.S. airlines operating during 2001. Using the Airline Quality Rating system of weighted averages and monthly performance data in the areas of on-time arrivals, involuntary denied boardings, mishandled baggage, and a combination of 12 customer complaint categories, airlines comparative performance for the calendar year of 2001 is reported. This research monograph contains a brief summary of the AQR methodology, detailed data and charts that track comparative quality for domestic airline operations for the 12-month period of 2001, and industry average results. Also, comparative Airline Quality Rating data for 2000 are included for each airline to provide historical perspective regarding performance quality in the industry.

  9. Strain rate sensitive constitutive equations

    E-print Network

    Nelson, Charles Edward

    1971-01-01

    , the dynamic yield for steel was much larger than that in the static case, and for copper it was only slightly higher. Consequently, steel has more 11 strain rate sensitivity than copper. Drucker considered several classes of mathematical theories of... and strain rate was that presented by Iiohenemser and 31 Prager in 1932. It was their work which attempted to define a possible rate sensitive constitutive equation. They t? eorized that the form of a constitutive equation could be defined as 2nd . . = 20...

  10. 47 CFR 64.1900 - Nondominant interexchange carrier certifications regarding geographic rate averaging and rate...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...regarding geographic rate averaging and rate integration requirements. 64.1900 Section...Regarding Geographic Rate Averaging and Rate Integration Requirements § 64.1900 Nondominant...regarding geographic rate averaging and rate integration requirements. (a) A...

  11. DEMOS for RELATED RATE Problems

    NSDL National Science Digital Library

    Roberts, Lila F.

    2002-02-11

    This demo provides a toolbox of visual aids that illustrate fundamental concepts for understanding and developing equations that model related rate problems. A gallery of animations for various problems is included.

  12. Raising Response Rates: What Works?

    ERIC Educational Resources Information Center

    Porter, Stephen R.

    2004-01-01

    This chapter discusses the theoretical literature on why people choose to respond to a survey and reviews the latest empirical research on how survey administration and the characteristics of a survey affect response rates. (Contains 1 figure.)

  13. Heart rate variability: a review

    Microsoft Academic Search

    U. Rajendra Acharya; Paul K. Joseph; N. Kannathal; Choo Min Lim; Jasjit S. Suri

    2006-01-01

    Heart rate variability (HRV) is a reliable reflection of the many physiological factors modulating the normal rhythm of the\\u000a heart. In fact, they provide a powerful means of observing the interplay between the sympathetic and parasympathetic nervous\\u000a systems. It shows that the structure generating the signal is not only simply linear, but also involves nonlinear contributions.\\u000a Heart rate (HR) is

  14. Rate of volcanism on Venus

    SciTech Connect

    Fegley, B. Jr.; Prinn, R.G.

    1988-07-01

    The maintenance of the global H/sub 2/SO/sub 4/ clouds on Venus requires volcanism to replenish the atmospheric SO/sub 2/ which is continually being removed from the atmosphere by reaction with calcium minerals on the surface of Venus. The first laboratory measurements of the rate of one such reaction, between SO/sub 2/ and calcite (CaCO/sub 3/) to form anhydrite (CaSO/sub 4/), are reported. If the rate of this reaction is representative of the SO/sub 2/ reaction rate at the Venus surface, then we estimate that all SO/sub 2/ in the Venus atmosphere (and thus the H/sub 2/SO/sub 4/ clouds) will be removed in 1.9 million years unless the lost SO/sub 2/ is replenished by volcanism. The required rate of volcanism ranges from about 0.4 to about 11 cu km of magma erupted per year, depending on the assumed sulfur content of the erupted material. If this material has the same composition as the Venus surface at the Venera 13, 14 and Vega 2 landing sites, then the required rate of volcanism is about 1 cu km per year. This independent geochemically estimated rate can be used to determine if either (or neither) of the two discordant (2 cu km/year vs. 200 to 300 cu km/year) geophysically estimated rates is correct. The geochemically estimated rate also suggests that Venus is less volcanically active than the Earth.

  15. Sensors for rate responsive pacing

    PubMed Central

    Dell'Orto, Simonetta; Valli, Paolo; Greco, Enrico Maria

    2004-01-01

    Advances in pacemaker technology in the 1980s have generated a wide variety of complex multiprogrammable pacemakers and pacing modes. The aim of the present review is to address the different rate responsive pacing modalities presently available in respect to physiological situations and pathological conditions. Rate adaptive pacing has been shown to improve exercise capacity in patients with chronotropic incompetence. A number of activity and metabolic sensors have been proposed and used for rate control. However, all sensors used to optimize pacing rate metabolic demands show typical limitations. To overcome these weaknesses the use of two sensors has been proposed. Indeed an unspecific but fast reacting sensor is combined with a more specific but slower metabolic one. Clinical studies have demonstrated that this methodology is suitable to reproduce normal sinus behavior during different types and loads of exercise. Sensor combinations require adequate sensor blending and cross checking possibly controlled by automatic algorithms for sensors optimization and simplicity of programming. Assessment and possibly deactivation of some automatic functions should be also possible to maximize benefits from the dual sensor system in particular conditions. This is of special relevance in patient whose myocardial contractility is limited such as in subjects with implantable defibrillators and biventricular pacemakers. The concept of closed loop pacing, implementing a negative feedback relating pacing rate and the control signal, will provide new opportunities to optimize dual-sensors system and deserves further investigation. The integration of rate adaptive pacing into defibrillators is the natural consequence of technical evolution. PMID:16943981

  16. Lung Cancer Rates by Race and Ethnicity

    MedlinePLUS

    ... and ethnicity. Incidence Rates by Race/Ethnicity and Sex "Incidence rate" means how many people out of ... Alaska Native). Death Rates by Race/Ethnicity and Sex From 1999â??2011, the rate of people dying ...

  17. Bit-rate selection in wireless networks

    E-print Network

    Bicket, John C. (John Charles)

    2005-01-01

    This thesis evaluates bit-rate selection techniques to maximize throughput over wireless links that are capable of multiple bit-rates. The key challenges in bit-rate selection are determining which bit-rate provides the ...

  18. Hardware implementation of wireless bit rate adaptation

    E-print Network

    Gross, Samuel A

    2010-01-01

    This thesis presents a hardware implementation of the SoftRate bit-rate adaptation protocol. SoftRate is a new bit-rate adaptation protocol, which uses per-bit confidence hints generated by the convolutional decoder to ...

  19. Bit-rate Selection in Wireless Networks

    Microsoft Academic Search

    John C. Bicket

    2005-01-01

    Abstract This thesis evaluates bit-rate selection techniques to maximize throughput over wireless links that are capable of multiple bit-rates. The key challenges in bit-rate selection are determining which bit-rate provides the most throughput and knowing when to switch to another bit-rate that would provide more throughput. This thesis presents the SampleRate bit-rate selection algorithm. SampleRate sends most data packets at

  20. Matching and Conditioned Reinforcement Rate

    PubMed Central

    Shahan, Timothy A; Podlesnik, Christopher A; Jimenez-Gomez, Corina

    2006-01-01

    Attempts to examine the effects of variations in relative conditioned reinforcement rate on choice have been confounded by changes in rates of primary reinforcement or changes in the value of the conditioned reinforcer. To avoid these problems, this experiment used concurrent observing responses to examine sensitivity of choice to relative conditioned reinforcement rate. In the absence of observing responses, unsignaled periods of food delivery on a variable-interval 90-s schedule alternated with extinction on a center key (i.e., a mixed schedule was in effect). Two concurrently available observing responses produced 15-s access to a stimulus differentially associated with the schedule of food delivery (S+). The relative rate of S+ deliveries arranged by independent variable-interval schedules for the two observing responses varied across conditions. The relation between the ratio of observing responses and the ratio of S+ deliveries was well described by the generalized matching law, despite the absence of changes in the rate of food delivery. In addition, the value of the S+ deliveries likely remained constant across conditions because the ratio of S+ to mixed schedule food deliveries remained constant. Assuming that S+ deliveries serve as conditioned reinforcers, these findings are consistent with the functional similarity between primary and conditioned reinforcers suggested by general choice theories based on the concatenated matching law (e.g., contextual choice and hyperbolic value-added models). These findings are inconsistent with delay reduction theory, which has no terms for the effects of rate of conditioned reinforcement in the absence of changes in rate of primary reinforcement. PMID:16673824