Decomposition technique and optimal trajectories for the aeroassisted flight experiment

An actual geosynchronous Earth orbit-to-low Earth orbit (GEO-to-LEO) transfer is considered with reference to the aeroassisted flight experiment (AFE) spacecraft, and optimal trajectories are determined by minimizing the total characteristic velocity. The optimization is performed with respect to the time history of the controls (angle of attack and angle of bank), the entry path inclination and the flight time being free. Two transfer maneuvers are considered: direct ascent (DA) to LEO and indirect ascent (IA) to LEO via parking Earth orbit (PEO). By taking into account certain assumptions, the complete system can be decoupled into two subsystems: one describing the longitudinal motion and one describing the lateral motion. The angle of attack history, the entry path inclination, and the flight time are determined via the longitudinal motion subsystem. In this subsystem, the difference between the instantaneous bank angle and a constant bank angle is minimized in the least square sense subject to the specified orbital inclination requirement. Both the angles of attack and the angle of bank are shown to be constant. This result has considerable importance in the design of nominal trajectories to be used in the guidance of AFE and aeroassisted orbital transfer (AOT) vehicles

Autonomous rendezvous targeting techniques for national launch system application

The rendezvous targeting techniques that can be utilized to achieve autonomous guidance for delivering a cargo to Space Station Freedom (SSF) using the National Launch System's (NLS) Heavy Lift Launch Vehicle (HLLV) and the on-orbit Cargo Transfer Vehicle (CTV) are described. This capability is made possible by advancements in autonomous navigation (Global Positioning System - GPS) on-board the CTV and SSF as well as the new generation flight computers. How the HLLV launch window can be decoupled from the CTV phasing window is described. The performance trades that have to be made to determine the length of the launch window and the phasing window between the CTV and SSF are identified and recommendations made that affect mission timelines

A plan for spacecraft automated rendezvous

An automated rendezvous approach has been developed that utilizes advances in technology to reduce real-time/near real-time flight operations support personnel to an acceptable level that is near the minimum without jeopardizing the success of the mission. The on-board flight targeting uses a rule-based system to select the pursuit vehicle phasing orbits and uses precise navigation updates from the pursuit/target spacecraft made possible by the global positioning system receivers/processors on both spacecraft to adjust the phasing orbits and achieve rendezvous. The ascent-to-orbit targeting for the pursuit vehicle has been successfully decoupled from the on-orbit orbit transfer phasing targeting. Typical launch window data have been developed for the heavy lift launch vehicle and cargo transfer vehicle for a Space Station Freedom rendezvous mission

Contour measurement system

A measurement system for measuring the departures from a straight line of discrete track sections of a track along a coal face in a mine employing a vehicle having a pair of spaced wheel assemblies which align with the track is presented. A reference arm pivotally connects between the wheel assemblies, and there is indicating means for measuring the angle of pivot between the arm and each of the wheel assemblies. The length of the device is less than the length of a track section, and thus when one of the wheel assemblies is on one track section and one is on an adjoining track section, the sum of the indicated angles will be indicative of the angle between track sections. Thus, from the length of a track section and angle, the departure of each track section from the line may be calculated

Equity Must Accompany Economic Growth for Good Health

K. Srinath Reddy discusses a new research study by S. V. Subramanian and colleagues that found no strong evidence of recent economic growth in India being associated with a reduction in child undernutrition

Arguing about Science: Empowering Students and Developing Issue-Based Pedagogies through Debate

This presentation will guide 4th-12th grade educators to engage students in using content area knowledge to solve real-world problems. Using an adaptation of policy debate, learners use facts and evidence gathered through their participation in Science and Engineering Practices to create resolutions to place-based issues that are occurring in their own communities

The Human Spirit: Anxiety, Spirituality, and Depression in HIV Adults

This poster examines the relationships between anxiety, spirituality, and depression in persons living with HIV

The Heterogeneous Impact of International Migration on Left‐behind Households: Evidence from Bangladesh

This article investigates the heterogeneous effects of international migration on the expenditure of Bangladeshi migrant households. Adopting a counterfactual framework, we estimate the impact of migration on per capita expenditure of left-behind households according to their position in the counterfactual expenditure distribution and the length of the migration period. The effects on households\u2019 social mobility and on inequality are also assessed. The analysis indicates that migration has a positive impact on per capita expenditure and represents an important vehicle of social mobility, but may also be a source of inequality. We also find that only a tiny share of international migrants originates from households belonging to the lowest expenditure quintile and, since most of the characteristics which seem to influence the migration decision cannot be shaped by policy interventions, our results also suggest that pro-migration policies might not be effective in lifting those most in need out of poverty

OMV Servicing Missions from Space Station

\u27!he Orbital Maneuvering Vehicle (OMV) will provide a means of bringing large observatories to the Space station for servicing and redeployment to their operating altitudes. However, there are many constraints which must be met in mission planning. \u27!he missions must be designed so that propellant consumption is within the usable allowance, but contingency operations can still be accomplished. \u27!he vehicle was designed specifically to accommodate such missions, with emphasis upon servicing the Hubble Space Telescope. \u27!he OMV has been designed for operations from the Shuttle Orbiter and the Space Station. It will readily accommodate basing at the Space Station and executing observatory retrieval and redeployment missions. Mission profiles have been designed which allow retrieval with contengency hold before descent, and which allow contengency return of the observatory if it fails to reactivate properly. This capability will be a major addition to the Space Transportation System and will increase the utility of the Space Station