SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
This report describes the atmospheric conditions under which ice is formed upon the exposed parts of airplanes in flight. It identifies the formation found under different conditions, and describes some studies of preventative means.
The cost of on-orbit operations remains a significant and increasingly visible concern in the support of satellite missions. Headway has been made in automating some ground operations; however, increased mission complexity and more precise orbital constraints have compelled continuing human involvement in mission design and maneuver planning operations. AI Solutions, Inc. in cooperation with the National Aeronautics and Space Administration's (NASA) Goddard Space Flight Center (GSFC) has tackled these more complex problems through the development of AutoCon as a tool for an automated solution. NASA is using AutoCon to automate the maneuver planning for the Earth Orbiter-1 (EO-1) mission. AutoCon was developed originally as a ground system tool. The EO-1 mission will be using a scaled version of AutoCon on-board the EO-1 satellite to command orbit adjustment maneuvers. The flight version of AutoCon plans maneuvers based on formation flying algorithms developed by GSFC, JPL, and other industry partners. In its fully autonomous mode, an AutoCon planned maneuver will be executed on-board the satellite without intervention from the ground. This paper describes how AutoCon automates maneuver planning for the formation flying constraints of the EO-1 mission. AutoCon was modified in a number of ways to automate the maneuver planning on-board the satellite. This paper describes how the interface and functionality of AutoCon were modified to support the on-board system. A significant component of this modification was the implementation of a data smoother, based on a Kalman filter, that ensures that the spacecraft states estimated by an on-board GPS receiver are as accurate as possible for maneuver planning. This paper also presents the methodology use to scale the AutoCon functionality to fit and execute on the flight hardware. This paper also presents the modes built that allow the incremental phasing in of autonomy. New technologies for autonomous operations are usually received with significant, and probably appropriate trepidation. A number of safeguards have been designed in both AutoCon and the interfacing systems to alleviate the potential of mission-impacting anomalies from the on-board autonomous system. This paper describes the error checking, input data integrity validation and limits set on maneuvers in AutoCon and the on-board system.
This document establishes the functional requirements of the Galileo Orbitor plasma wave subsystem (PWS) which is used to investigate electric and magnetic waves in space plasmas.
The results of a piloted simulation experiment to evaluate the effect of integrating flight path angle information into a typical transport electronic attitude director indicator display format for flight director instrument landing system approaches are presented. Three electronic display formats are evaluated during 3 deg straight-in approaches with wind shear and turbulence conditions. Flight path tracking data and pilot subjective comments are analyzed with regard to the pilot's tracking performance and workload for all three display formats.
The loss of weight bearing during spaceflight results in osteopenia in humans. Decrements in bone mineral reach 3-10% after as little as 75-184 days in space. Loss of bone mineral during flight decreases bone strength and increases fracture risk. The mechanisms responsible for, and the factors contributing to, the changes in bone induced by spaceflight are poorly understood. The rat has been widely used as an animal model for human bone loss during spaceflight. Despite its potential usefulness, the results of bone studies performed in the rat in space have been inconsistent. In some flights bone formation is decreased and cancellous bone volume reduced, while in others no significant changes in bone occur. In June of 1996 Drs. T. Wronski, S. Miller and myself participated in a flight experiment (STS 78) to examine the effects of glucocorticoids on bone during weightlessness. Technically the 17 day flight experiment was flawless. The results, however, were surprising. Cancellous bone volume and osteoblast surface in the proximal tibial metaphysis were the same in flight and ground-based control rats. Normal levels of cancellous bone mass and bone formation were also detected in the lumbar vertebrae and femoral neck of flight rats. Furthermore, periosteal bone formation rate was found to be identical in flight and ground-based control rats. Spaceflight had little or no effect on bone metabolism! These results prompted us to carefully review the changes in bone observed in, and the flight conditions of previous spaceflight missions.
This slide presentation examines the current and future state of formation flying, LEO formations, control strategies for flight in the vicinity of the libration points, and distant retrograde orbit formations. This discussion of LEO formations includes background on perturbation theory/accelerations and LEO formation flying. The discussion of strategies for formation flight in the vicinity of the libration points includes libration missions and natural and controlled libration orbit formations. A reference list is included.
Autonomous rendezvous and docking (AR&D) is a critical need for manned spaceflight, especially in deep space where communication delays essentially leave crews on their own for critical operations like docking. Previously developed AR&D sensors have been large, heavy, power-hungry, and may still require further development (e.g. Flash LiDAR). Other approaches to vision-based navigation are not computationally efficient enough to operate quickly on slower, flight-like computers. The key technical challenge for visual odometry is to adapt it from the current terrestrial applications it was designed for to function in the harsh lighting conditions of space. This effort leveraged Draper Laboratory’s considerable prior development and expertise, benefitting both parties. The algorithm Draper has created is unique from other pose estimation efforts as it has a comparatively small computational footprint (suitable for use onboard a spacecraft, unlike alternatives) and potentially offers accuracy and precision needed for docking. This presents a solution to the AR&D problem that only requires a camera, which is much smaller, lighter, and requires far less power than competing AR&D sensors. We have demonstrated the algorithm’s performance and ability to process ‘flight-like’ imagery formats with a ‘flight-like’ trajectory, positioning ourselves to easily process flight data from the upcoming ‘ISS Selfie’ activity and then compare the algorithm’s quantified performance to the simulated imagery. This will bring visual odometry beyond TRL 5, proving its readiness to be demonstrated as part of an integrated system.Once beyond TRL 5, visual odometry will be poised to be demonstrated as part of a system in an in-space demo where relative pose is critical, like Orion AR&D, ISS robotic operations, asteroid proximity operations, and more.
Autonomous rendezvous and docking (AR&D) is a critical need for manned spaceflight, especially in deep space where communication delays essentially leave crews on their own for critical operations like docking. Previously developed AR&D sensors have been large, heavy, power-hungry, and may still require further development (e.g. Flash LiDAR). Other approaches to vision-based navigation are not computationally efficient enough to operate quickly on slower, flight-like computers. The key technical challenge for visual odometry is to adapt it from the current terrestrial applications it was designed for to function in the harsh lighting conditions of space. This effort leveraged Draper Laboratory's considerable prior development and expertise, benefitting both parties. The algorithm Draper has created is unique from other pose estimation efforts as it has a comparatively small computational footprint (suitable for use onboard a spacecraft, unlike alternatives) and potentially offers accuracy and precision needed for docking. This presents a solution to the AR&D problem that only requires a camera, which is much smaller, lighter, and requires far less power than competing AR&D sensors. We have demonstrated the algorithm's performance and ability to process 'flight-like' imagery formats with a 'flight-like' trajectory, positioning ourselves to easily process flight data from the upcoming 'ISS Selfie' activity and then compare the algorithm's quantified performance to the simulated imagery. This will bring visual odometry beyond TRL 5, proving its readiness to be demonstrated as part of an integrated system. Once beyond TRL 5, visual odometry will be poised to be demonstrated as part of a system in an in-space demo where relative pose is critical, like Orion AR&D, ISS robotic operations, asteroid proximity operations, and more.
The headward shift of body fluid and increase in stress-related hormones that occur in hypogravity bring about a number of changes in metabolism and biochemistry of the human body. Such alterations may have important effects on health during flight and during a recovery period after return to earth. Body fluid and electrolytes are lost, and blood levels of several hormones that control metabolism are altered during space flight. Increased serum calcium may lead to an increased risk of renal stone formation during flight, and altered drug metabolism could influence the efficacy of therapeutic agents. Orthostatic intolerance and an increased risk of fracturing weakened bones are concerns at landing. It is important to understand biochemistry and metabolism in hypogravity so that clinically important developments can be anticipated and prevented or ameliorated.
A simulator evaluation of a cockpit display format for hovering flight is described. The display format is based upon the position-velocity-acceleration representation (PVA) similar to that used in the Pilot Night Vision System in the Army AH-64 helicopter. By only varying the nature of the display law driving the 'primary' indicator in the PVA format, i.e. the acceleration symbol, three candidate displays are created and evaluated. These range from a Status display in which the primary indicator provides true acceleration information to a Command display, in which the primary indicator provides flight director information. Simulation results indicate that two of the three displays offer performance and handling qualities which make them excellent candidates for future helicopter cockpit display systems.
A simulator evaluation of a cockpit display format for hovering flight is described. The display format is based on the position-velocity-acceleration representation (PVA) similar to that used in the Pilot Night Vision System in the Army AH-64 helicopter. By only varying the nature of the display law driving the primary indicator in the PVA format, i.e., the acceleration symbol, three candidate displays are created and evaluated. These range from a Status display in which the primary indicator provides true acceleration information to a Command display, in which the primary indicator provides flight director information. Simulation results indicate that two of the three displays offer performance and handling qualities which make them excellent candidates for future helicopter cockpit display systems.
This paper presents results of a flight evaluation of two electronic display formats for the approach-to-landing under instrument conditions. The evaluation was conducted for a baseline electronic display format and for the same format with runway symbology and track information added; its evaluation was conducted during 3-deg manual straight-in approaches with and without initial localizer offsets. Flight-path tracking performance data and pilot subjective comments were examined with regard to pilot's ability to capture and maintain the localizer and glide slope using both display fomats. The results of the flight tests agree with earlier simulation results and show that the addition of a perspective runway symbol with an extended centerline and relative track information to a baseline electronic display format improved both lateral and vertical flight-path tracking. Pilot comments indicated that the mental workload required to assess the approach situation was reduced as a result of integrating the perspective runway with extended centerline along with relative track information into the vertical situation display. The limited flight-test results also show that the flight-path performance with the integrated situation display format meets Category II Flight-Director performance criteria.
Previous studies have shown that a decrease in red cell mass occurs in astronauts, and some studies indicate a leukocytosis occurs. A life science module housing young and mature rats was flown on shuttle mission Spacelab 3 (SL-3), and the results of hematology studies of flight and control rats are presented. Statistically significant increases in the hematocrit, red blood cell counts, and hemoglobin determinations, together with a mild neutrophilia and lymphopenia, were found in flight animals. No significant changes were found in bone marrow and spleen cell differentials or erythropoietin determinations. Clonal assays demonstrated an increased erythroid colony formation of flight animal bone marrow cells at erythropoietin doses of 0.02 and 1.0 U/ml but not 0.20 U/ml. These results agree with some but vary from other previously published studies. Erythropoietin assays and clonal studies were performed for the first time.
Addressing the question of whether the bone formed in space is unusual, the morphology of bone made at the tibial diaphysis of rats before, during, and after spaceflight is studied. Evidence of arrest lines in the bone formed in space is reported suggesting that bone formation ceases along portions of the periosteum during spaceflight. Visualized by microradiography, the arrest lines are shown to be less mineralized than the surrounding bone matrix. When viewed by scanning electron microscopy, it is seen that bone fractures more readily at the site of an arrest line. These observations are seen as suggesting that arrest lines are a zone of weakness and that their formation may result in decreased bone strength in spite of normalization of bone formation after flight. The occurrence, location, and morphology of arrest lines are seen as suggesting that they are a visible result of the phenomenon of arrested bone formation.
Peculiarities in the formation of the andrecium and gynecium elements are described for Arabidopsis plants grown from the stages of two cotyledonous leaves in the Svitoblok-1 device on board the Salyut 6 orbital research station and in the laboratory. It is established that flower buds and flowers, normally formed in habitus, contain sterile elements of andrecium and gynecium whose degeneration occurs at different developmental stages of the Arabidopsis plants in the experiment under conditions of weightlessness.
A retrospective consideration of two 15-year old Guidance, Navigation and Control (GN&C) technology 'vision' predictions will be the focus of this paper. A look back analysis and critique of these late 1990s technology roadmaps out-lining the future vision, for two then nascent, but rapidly emerging, GN&C technologies will be performed. Specifically, these two GN&C technologies were: 1) multi-spacecraft formation flying and 2) the spaceborne use and exploitation of global positioning system (GPS) signals to enable formation flying. This paper reprises the promise of formation flying and spaceborne GPS as depicted in the cited 1999 and 1998 papers. It will discuss what happened to cause that promise to be mostly unfulfilled and the reasons why the envisioned formation flying dream has yet to become a reality. The recent technology trends over the past few years will then be identified and a renewed government interest in spacecraft formation flying/cluster flight will be highlighted. The authors will conclude with a reality-tempered perspective, 15 years after the initial technology roadmaps were published, predicting a promising future of spacecraft formation flying technology development over the next decade.
The results of a flight evaluation of two electronic display formats for the approach to landing under instrument conditions are presented. The evaluation was conducted for a base-line electronic display format and for the same format with runway symbology and track information added. The evaluation was conducted during 3 deg, manual straight-in approaches with and without initial localizer offsets. Flight path tracking performance data and pilot subjective comments were examined with regard to the pilot's ability to capture and maintain localizer and glide slope by using both display formats.
The cost of on-orbit operations remains a significant and increasingly visible concern in the support of satellite missions. Headway has been made in automating some ground operations; however, increased mission complexity and more precise orbital constraints have compelled continuing human involvement in mission design and maneuver planning operations. AI Solutions, Inc. in cooperation with the National Aeronautics and Space Administration's (NASA) Goddard Space Flight Center (GSFC) has tackled these more complex problems through the development of AutoCon(TM) as a tool for an automated solution. NASA is using AutoCon(TM) to automate the maneuver planning for the Earth Orbiter-1 (EO-1) mission. AutoCon(TM) was developed originally as a ground system tool. The EO-1 mission will be using a scaled version of AutoCon(TM) on-board the EO-1 satellite to command orbit adjustment maneuvers. The flight version of AutoCon(TM) plans maneuvers based on formation flying algorithms developed by GSFC, JPL, and other industry partners. In its fully autonomous mode, an AutoCon(TM) planned maneuver will be executed on-board the satellite without intervention from the ground. This paper describes how AutoCon(TM) automates maneuver planning for the formation flying constraints of the EO-1 mission. AutoCon(TM) was modified in a number of ways to automate the maneuver planning on-board the satellite. This paper describes how the interface and functionality of AutoCon(TM) were modified to support the on-board system. A significant component of this modification was the implementation of a data smoother, based on a Kalman filter, that ensures that the spacecraft states estimated by an on-board GPS receiver are as accurate as possible for maneuver planning. This paper also presents the methodology used to scale the AutoCon(TM) functionality to fit and execute on the flight hardware. This paper also presents the modes built into the system that allow the incremental phasing in of autonomy. New technologies for autonomous operations are usually received with significant, and probably appropriate, trepidation. A number of safeguards have been designed in both AutoCon(TM) and the interfacing systems to alleviate the potential of mission-impacting anomalies from the on-board autonomous system. This paper describes the error checking, input data integrity validation, and limits set on maneuvers in AutoCon(TM) and the on-board system.