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At least 1,387 records · Page 77
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NASA NTRS2005

Off-Nominal Performance of the International Space Station Solar Array Wings Under Orbital Eclipse Lighting Scenarios

This paper documents testing and analyses to quantify International Space Station (ISS) Solar Array Wing (SAW) string electrical performance under highly off-nominal, low-temperature-low-intensity (LILT) operating conditions with nonsolar light sources. This work is relevant for assessing feasibility and risks associated with a Sequential Shunt Unit (SSU) remove and replace (R&R) Extravehicular Activity (EVA). During eclipse, SAW strings can be energized by moonlight, EVA suit helmet lights or video camera lights. To quantify SAW performance under these off-nominal conditions, solar cell performance testing was performed using full moon, solar simulator and Video Camera Luminaire (VCL) light sources. Test conditions included 25 to 110 C temperatures and 1- to 0.0001-Sun illumination intensities. Electrical performance data and calculated eclipse lighting intensities were combined to predict SAW current-voltage output for comparison with electrical hazard thresholds. Worst case predictions show there is no connector pin molten metal hazard but crew shock hazard limits are exceeded due to VCL illumination. Assessment uncertainties and limitations are discussed along with operational solutions to mitigate SAW electrical hazards from VCL illumination. Results from a preliminary assessment of SAW arcing are also discussed. The authors recommend further analyses once SSU, R&R, and EVA procedures are better defined.

Kerslake, Thomas W.↗
NASA NTRS2006

EV13 Genesis Reentry Observations and Data Analysis

The Genesis spacecraft reentry represented a unique opportunity to observe a "calibrated meteor" from northern Nevada. Knowing its speed, mass, composition, and precise trajectory made it a good subject to test some of the algorithms used to determine meteoroid mass from observed brightness. It was also a good test of an inexpensive set of cameras which could be deployed to observe future shuttle reentries. The utility of consumer grade video cameras was evident during the STS-107 accident investigation and the Genesis reentry gave us the opportunity to specify and test commercially available cameras which could be used during future reentries. This report describes the video observations and their analysis, compares the results with a simple photometric model, describes the forward scatter radar experiment, and lists lessons learned from the expedition and implications for the Stardust reentry in January 2006 as well as future shuttle reentries.

Swift, Wesley R.↗
NASA NTRS2006

The Boiling eXperiment Facility (BXF) for the Microgravity Science Glovebox (MSG)

Boiling is an effective means of cooling by removing heat from surfaces through vaporization of a working fluid. It is also affected by both the magnitude and direction of gravity. By conducting pool boiling tests in microgravity, the effect of buoyancy n the overall boiling process and the relative magnitude of other phenomena can be assessed. The Boiling eXperiment Facility (BXF) is being built for the Microgravity Science Glovebox. This facility will conduct two pool boiling studies. The first study the Microheater Array Boiling Experiment (MABE) uses two 96 element microheater arrays, 2.7 mm and 7.0 mm in size, to measure localized hear fluxes while operating at a constant temperature. The other experiment, the Nucleate Pool Boiling eXperiment (NPBX) uses a 85 mm diameter heater wafer that has been "seeded" with five individually-controlled nucleation sites to study bubble nucleation, growth, coalescence and departure. The BXF uses normal-perfluorohexane as the test fluid and will operate between pressures of 60 to 244 Pa. and temperatures of 35 to 60 C. Both sets of experimental heaters are highly instrumented. Pressure and bulk fluid temperature measurements will be made with standard rate video. A high speed video system will be used to visualize the boiling process through the bottom of the MABE heater arrays. The BXF is currently scheduled to fly on Utilization Flight-13A.1 to the ISS with facility integration into the MSG and operation during Increment 15

McQuillen, John↗
NASA NTRS2005

Genesis Reentry Observations and Data Analysis

The Genesis spacecraft reentry represented a unique opportunity to observe a "calibrated meteor" from northern Nevada. Knowing its speed, mass, composition, and precise trajectory made it a good subject to test some of the algorithms used to determine meteoroid mass from observed brightness. It was also a good test of an inexpensive set of cameras that could be deployed to observe future shuttle reentries. The utility of consumer-grade video cameras was evident during the STS-107 accident investigation, and the Genesis reentry gave us the opportunity to specify and test commercially available cameras that could be used during future reentries. This Technical Memorandum describes the video observations and their analysis, compares the results with a simple photometric model, describes the forward scatter radar experiment, and lists lessons learned from the expedition and implications for the Stardust reentry in January 2006 as well as future shuttle reentries.

Suggs, R. M.↗
NASA NTRS2006

Earth's Earliest Ecosystems in the C: The Use of Microbial Mats to Demonstrate General Principles of Scientific Inquiry and Microbial Ecology

Microbial mats are living examples of the most ancient biological communities on Earth. As Earth's earliest ecosystems, they are centrally important to understanding the history of life on our planet and are useful models for the search for life elsewhere. As relatively compact (but complete) ecosystems, microbial mats are also extremely useful for educational activities. Mats may be used to demonstrate a wide variety of concepts in general and microbial ecology, including the biogeochemical cycling of elements, photosynthesis and respiration, and the origin of the Earth's present oxygen containing atmosphere. Microbial mats can be found in a number of common environments accessible to teachers, and laboratory microbial mats can be constructed using materials purchased from biological supply houses. With funding from NASA's Exobiology program, we have developed curriculum and web-based activities centered on the use of microbial mats as tools for demonstrating general principles in ecology, and the scientific process. Our web site (http://microbes.arc.nasa.gov) includes reference materials, lesson plans, and a "Web Lab", featuring living mats maintained in a mini-aquarium. The site also provides information as to how research on microbial mats supports NASA's goals, and various NASA missions. A photo gallery contains images of mats, microscopic views of the organisms that form them, and our own research activities. An animated educational video on the web site uses computer graphic and video microscopy to take students on a journey into a microbial mat. These activities are targeted to a middle school audience and are aligned with the National Science Standards.

Bebout, Brad M.↗
NASA NTRS2006

The F-15B Lifting Insulating Foam Trajectory (LIFT) Flight Test

A series of flight tests has been performed to assess the structural survivability of space shuttle external tank debris, known as divots, in a real flight environment. The NASA F-15B research test bed aircraft carried the Aerodynamic Flight Test Fixture configured with a shuttle foam divot ejection system. The divots were released in flight at subsonic and supersonic test conditions matching points on the shuttle ascent trajectory. Very high-speed digital video cameras recorded the divot trajectories. The objectives of the flight test were to determine the structural survivability of the divots in a real flight environment, assess the aerodynamic stability of the divots, and provide divot trajectory data for comparison with debris transport models. A total of 10 flights to Mach 2 were completed, resulting in 36 successful shuttle foam divot ejections. Highspeed video was obtained at 2,000 pictures per second for all of the divot ejections. The divots that were cleanly ejected remained structurally intact. The conical frustum-shaped divots tended to aerodynamically trim in both the subsonic and supersonic free-stream flow.

Corda, Stephen↗
NASA NTRS2006

STS-121/Discovery Preflight Briefing Program Overview

Wayne Hale (Space Shuttle Program Manager) opens with a short video of the external tank operation and the Shuttle roll out to the launch pad. Kirk Shireman (International Space Station Program Deputy Manager) shows a video of International Space Station activities which included replacement of the remote power switch, unloading of cargo, Earth observation (over 23,000 photos taken), exercises, and replacement of the Camera during a spacewalk.

Source record↗
NASA NTRS2005

Enhanced Lighting Techniques and Augmented Reality to Improve Human Task Performance

One of the most versatile tools designed for use on the International Space Station (ISS) is the Special Purpose Dexterous Manipulator (SPDM) robot. Operators for this system are trained at NASA Johnson Space Center (JSC) using a robotic simulator, the Dexterous Manipulator Trainer (DMT), which performs most SPDM functions under normal static Earth gravitational forces. The SPDM is controlled from a standard Robotic Workstation. A key feature of the SPDM and DMT is the Force/Moment Accommodation (FMA) system, which limits the contact forces and moments acting on the robot components, on its payload, an Orbital Replaceable Unit (ORU), and on the receptacle for the ORU. The FMA system helps to automatically alleviate any binding of the ORU as it is inserted or withdrawn from a receptacle, but it is limited in its correction capability. A successful ORU insertion generally requires that the reference axes of the ORU and receptacle be aligned to within approximately 0.25 inch and 0.5 degree of nominal values. The only guides available for the operator to achieve these alignment tolerances are views from any available video cameras. No special registration markings are provided on the ORU or receptacle, so the operator must use their intrinsic features in the video display to perform the pre-insertion alignment task. Since optimum camera views may not be available, and dynamic orbital lighting conditions may limit viewing periods, long times are anticipated for performing some ORU insertion or extraction operations. This study explored the feasibility of using augmented reality (AR) to assist with SPDM operations. Geometric graphical symbols were overlaid on the end effector (EE) camera view to afford cues to assist the operator in attaining adequate pre-insertion ORU alignment.

Maida, James C.↗
NASA NTRS2006

STS-121: Discovery L-2 Countdown Status Briefing

Bruce Buckingham from NASA Public Affairs introduces Pete Nicolenko, NASA Test Director, and Kathy Winters, Shuttle Weather Officer. During this STS-121 two days before launch countdown briefing, Pete Nicolenko says that there are no issues of concern and that they are on schedule for launch. He then presents and discusses an Orbiter Processing Facility (OPF) video. The OPF topics of discussion include: 1) Wheel and tire installation; 2) Gap filler installation; 3) Booster build-up; 4) Transport of External Tank (ET) 119; 5) ET to Shuttle Rocket Booster (SRB) Mate operation; 6) Roll-over of Discovery out of OPF to the Vehicle Assembly Building (VAB); and 7) Roll-out to the pad. Kathy Winters gives her weather forecast for the STS-121 launch. The video ends with a question and answer period from the media.

Source record↗
NASA NTRS2006

STS-121: Discovery Mission Overview Briefing

Tony Ceccacci, Lead STS-121 Space Shuttle Flight director, and Rick LaBrode, Lead STS-121 ULF 1.1 International Space Station Flight Director, are shown in this STS-121 Discovery mission overview. Ceccacci begins with an overview of the mission and gives the mission goals. He also presents various slides of the STS-121 payload that includes: 1) Orbiter Docking System; 2) Integrated Cargo Carrier (ICC); 3) Multipurpose Logistics Module (MPLM); 4) TPS Sample Box Assembly; 5) Shuttle Remote Manipulator System (SRMS); and 6) Orbiter Boom Sensor System (OBSS). He shows a video presentation on the various processes involved in the inspections of the Orbiter that include: 1) Unberthing OBSS; 2) Starboard wing leading edge survey; 3) Wing leading edge passes; 4) Nose cap surveys; 5) Port side surveys; and 6) Docking with the International Space Station. Ceccacci ends his presentation with discussing the work performed from flight day 1 to flight day 14. Rick LaBrode begins with discussing the on-orbit status of the Expedition 13 crew. He then presents a video of the MPLM installation, forward hatch of MPLM, resupply stowage platform, resupply stowage racks, and Oxygen Generator System (OGS) rack. Questions are answered from the media.

Source record↗
NASA NTRS1993

(abstract) Geological Tour of Southwestern Mexico

Nineteen Landsat Themic Mapper quarter scenes, coregistered at 28.5 m spatial resolution with three arc second digital topographic data, were used to create a movie, simulating a flight over the Guerrero and Mixteco terrains of southwestern Mexico. The flight path was chosen to elucidate important structural, stratigraphic, and geomorphic features. The video, available in VHS format, is a 360 second animation consisting of 10 800 total frames. The simulated velocity during three 120 second flight segments of the video is approximately 37 000 km per hour, traversing approximately 1 000 km on the ground.

Landsat Thematic Mapper Mexico animation↗
NASA NTRS2006

Remote Sensing Time Series Product Tool

The TSPT (Time Series Product Tool) software was custom-designed for NASA to rapidly create and display single-band and band-combination time series, such as NDVI (Normalized Difference Vegetation Index) images, for wide-area crop surveillance and for other time-critical applications. The TSPT, developed in MATLAB, allows users to create and display various MODIS (Moderate Resolution Imaging Spectroradiometer) or simulated VIIRS (Visible/Infrared Imager Radiometer Suite) products as single images, as time series plots at a selected location, or as temporally processed image videos. Manually creating these types of products is extremely labor intensive; however, the TSPT development tool makes the process simplified and efficient. MODIS is ideal for monitoring large crop areas because of its wide swath (2330 km), its relatively small ground sample distance (250 m), and its high temporal revisit time (twice daily). Furthermore, because MODIS imagery is acquired daily, rapid changes in vegetative health can potentially be detected. The new TSPT technology provides users with the ability to temporally process high-revisit-rate satellite imagery, such as that acquired from MODIS and from its successor, the VIIRS. The TSPT features the important capability of fusing data from both MODIS instruments onboard the Terra and Aqua satellites, which drastically improves cloud statistics. With the TSPT, MODIS metadata is used to find and optionally remove bad and suspect data. Noise removal and temporal processing techniques allow users to create low-noise time series plots and image videos and to select settings and thresholds that tailor particular output products. The TSPT GUI (graphical user interface) provides an interactive environment for crafting what-if scenarios by enabling a user to repeat product generation using different settings and thresholds. The TSPT Application Programming Interface provides more fine-tuned control of product generation, allowing experienced programmers to bypass the GUI and to create more user-specific output products, such as comparison time plots or images. This type of time series analysis tool for remotely sensed imagery could be the basis of a large-area vegetation surveillance system. The TSPT has been used to generate NDVI time series over growing seasons in California and Argentina and for hurricane events, such as Hurricane Katrina.

Predos, Don↗
NASA NTRS2007

Risk Reduction and Measures of Injury for EVA Associated Upper Extremity Medical Issues: Extended Vent Tube Study

During Neutral Buoyancy Lab (NBL) training sessions, a large amount of moisture accumulates in the EVA gloves. The glove design restricts the extension of the EVA suit s ventilation/cooling system to the hand. Subungual redness and fingernail pain develops for many astronauts following their NBL training sessions with subsequent oncholysis occurring over succeeding weeks. Various attempts have been made to reduce or avoid this problem. The causal role of moisture has yet to be defined. Methods: To determine the contribution that moisture plays in the injury to the fingers and fingernails during EVA training operations in NBL, the current Extravehicular Mobility Unit (EMU), with a Portable Life Support System (PLSS) was configured with a ventilation tube that extended down a single arm of the crewmember during the test and compared with the unventilated contralateral arm; with the ventilated hand serving as the experimental condition (E) and the opposite arm as the control (C). A cross-over design was used with opposite handedness for the vent tube on a subsequent NBL training run. Moisture content measures were conducted at six points on each hand with three types of moisture meters. A questionnaire was administered to determine subjective thermal hand discomfort, skin moisture perception, and hand and nail discomfort. Photographs and video were recorded. Measures were applied to six astronauts pre- and post-run in the NBL. Results: The consistent trends in relative hydration ratios at the dorsum, from 3.34 for C to 2.11 for E, and first ring finger joint locations, from 2.46 for C to 1.96 for E, indicated the extended vent tube promoted skin drying. The experimental treatment appeared to be more effective on the left hand versus the right hand, implying an interaction with hand anthropometry and glove fit. Video analyses differentiated fine and gross motor training tasks during runs and will be discussed. Conclusions: This potential countermeasure was effective in reducing the risks of hand and nail discomfort symptoms from moderate to low in two of six subjects. Improved design in the ventilation pattern of such a countermeasure is expected to improve the countermeasure s efficiency.

Jones, Jeffrey A.↗
NASA NTRS2004

DSP Implementation of the Multiscale Retinex Image Enhancement Algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/ spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.

Hines, Glenn D.↗
NASA NTRS2007

AVGS, AR and D for Satellites, ISS, the Moon, Mars and Beyond

With the continuous need to rotate crew and re-supply the International Space Station (ISS) and the desire to return humans to the Moon and for the first time, place humans on Mars, NASA must develop a more robust and highly reliable capability to perform Autonomous Rendezvous and Capture (AR&C) because, unlike the Apollo missions, NASA plans to send the entire crew to the Lunar or Martian surface and must be able to dock with the Orion spacecraft upon return. In 1997, NASA developed the Video Guidance Sensor (VGS) which was flown and tested on STS-87 and STS-95. In 2001, NASA designed and built a more enhanced version of the VGS, called the Advanced Video Guidance Sensor (AVGS). The AVGS offered significant technology improvements to the precursor VGS design. This paper will describe the AVGS as it was in the DART mission of 2005 and the Orbital Express mission of 2007. The paper will describe the capabilities and design concepts of the AVGS as it was flown on the DART 2005 Mission and the DARPA Orbital Express Mission slated to fly in 2007. The paper will cover the Flight Software, problems encountered, testing for Orbital Express and where NASA is going in the future.

Hintze, Geoffrey C.↗
NASA NTRS2006

Rotating Brush Seal

The proven technology of brush seals has been extended to the mitigation of problems arising from friction and wear at the bristle-rotor interface at high surface speeds. In prototype testing, the brush is mounted on, and free to rotate with the shaft, thus providing a complaint primary seal. A face seal positioned between the backing plate of the brush seal and the housing provides a secondary seal. The purpose of this paper is to demonstrate the interaction between the brush bristles and the shaft at high surface speeds as well as introduce a numerical model to simulate the bristle behavior. A test facility was constructed to study the effects of centrifugal forces on bristle deflection in a single rotating brush seal. The bristle-rotor interface was observed through a video camera, which utilized a high magnification borescope and a high frequency strobe light source. Rotational speeds of the rotor and the brush seal were measured by a magnetic and optical speed sensor, respectively. Preliminary results with speeds up to 11,000 rpm show no speed differential between the brush seal and rotor, or any instability problems associated with the brush seal. Bristle liftoff from the rotor is successfully captured on video.

Lattime, S. B.↗
NASA NTRS2000

Real time simulation using position sensing

An interactive exercise system including exercise equipment having a resistance system, a speed sensor, a controller that varies the resistance setting of the exercise equipment, and a playback device for playing pre-recorded video and audio. The controller, operating in conjunction with speed information from the speed sensor and terrain information from media table files, dynamically varies the resistance setting of the exercise equipment in order to simulate varying degrees of difficulty while the playback device concurrently plays back the video and audio to create the simulation that the user is exercising in a natural setting such as a real-world exercise course.

Studor, George F.↗
NASA NTRS1980

Edge smoothing for real-time simulation of a polygon face object system as viewed by a moving observer

The visual system within an aircraft flight simulation system receives flight data and terrain data which is formated into a buffer memory. The image data is forwarded to an image processor which translates the image data into face vertex vectors Vf, defining the position relationship between the vertices of each terrain object and the aircraft. The image processor then rotates, clips, and projects the image data into two-dimensional display vectors (Vd). A display generator receives the Vd faces, and other image data to provide analog inputs to CRT devices which provide the window displays for the simulated aircraft. The video signal to the CRT devices passes through an edge smoothing device which prolongs the rise time (and fall time) of the video data inversely as the slope of the edge being smoothed. An operational amplifier within the edge smoothing device has a plurality of independently selectable feedback capacitors each having a different value. The values of the capacitors form a series which doubles as a power of two. Each feedback capacitor has a fast switch responsive to the corresponding bit of a digital binary control word for selecting (1) or not selecting (0) that capacitor. The control word is determined by the slope of each edge. The resulting actual feedback capacitance for each edge is the sum of all the selected capacitors and is directly proportional to the value of the binary control word. The output rise time (or fall time) is a function of the feedback capacitance, and is controlled by the slope through the binary control word.

Lotz, Robert W.↗