Defense Meteorological Satellite Program

The DMSP is a total satellite system composed of spacecraft with meteorological sensors, an earthbased command and control network, fixed and mobile user stations, and a communication network linking the various segments together.     

Navigating towards the future: transitioning from terrestrial radio navigation to satellite navigation and airborne surveillance

This paper presents a proposal for transitioning from terrestrial-based navigation aids to implementing satellite and airborne surveillance as the primary navigation means. The transition occurs through several steps. First, the installation and use of modern navigation and surveillance equipment is mandated by the regulatory organizations. The installations should take place in a sequenced fashion to allow time for companies to absorb the initial cost. Next, the existing network of terrestrial navigation aids is down-sized leaving only the areas of heaviest use in service. At this point, the global positioning system (GPS) will be deemed the primary method of terrestrial and oceanic travel. Finally, terrestrial navigation stations will be available around airports and the remaining stations will be put in a standby condition for use in the event of a national emergency. This paper will discuss the security benefits and examples of cost savings through implementation of these steps.     

Minimizing human-machine interface failures in high risk systems

Technology now permits the building of very complex man-machine systems with centralized controls, with the result that many processes can be run by relatively few individual workers. Studies of failures within these complex systems indicate that they are usually the consequence of a series of highly complex coincidences. There is an institutional neglect or misunderstanding of the implications of low-probability, high-consequence events for the design of complex man-machine systems. We must stop designing systems in which we virtually guarantee that operator errors will occur with catastrophic consequences. The greatest payback in reducing high risk system accidents is to reduce catastrophes induced or exacerbated by human error. This paper discusses some task breakdowns between the human element and software/hardware. These task allocations allow the complex man-machine system to be designed more robustly and prevent human error so as to reduce possible catastrophic consequences     

A root moisture sensor for plants in microgravity.

Development of components for bioregenerative life-support systems is a vital step toward long-term space exploration. The culturing of plants in a microgravity environment may be optimized by the use of appropriate sensors and controllers. This paper describes a sensor developed for determining the amount of fluid (nutrient solution) available on the surface of a porous ceramic nutrient delivery substrate to the roots of conventional crop plants. The sensor is based on the change in thermal capacitance and thermal conductance near the surface as the moisture content changes. The sensor could be employed as a data acquisition and control sensor to support the automated monitoring of plants grown in a microgravity environment.     

Measurements of electrical breakdown in the vicinity of a sounding rocket differentially charged to 10 kV

During the initial period of high voltage biasing of the SPEAR-3 sounding rocket payload, it was observed that electrical breakdown occurred in the gas surrounding the rocket. The breakdown occurred almost all the way to apogee of 289 km on the upleg, but did not recur on the downleg until the payload reached an altitude of 100 km. It is suggested that this behavior can be attributed to payload outgassing on the upleg leading to abnormally high gas pressure near the payload skin. Consideration of a modified Paschen discharge process with varying pressure along the discharge path was found to be consistent with the results.     

Monitoring power supply current and using a neural network routineto diagnose circuit faults

As a circuit is tested, the current drawn from a power supply can vary as different functions are invoked by the test. The current draw can be plotted against time, showing a characteristic trace for the test performed. Sensors in the ATS power supply can be used to monitor the current flow during test execution. Defective components can be classified using a Neural Network according to the pattern of variation from the “trace” of a good card. This can be performed as a background function, with the network gaining in accuracy over time. This paper discusses the Neural Network Routine for diagnosing circuit faults using monitored power supply current     

Weapons System Open Architecture - a bridge between "embedded" and "off-board"

A demonstration program is described: Weapons System Open Architecture (WSOA) - funded jointly by the Air Force Research Laboratory (AFRL), DARPA, and the Open Systems Joint Task Force (OSJTF). WSOA provides an open systems "bridge" between legacy embedded mission systems and off-board C3I sources and systems. This "bridge" is used to support Internet-like connectivity between command and attack nodes. The foundation of this bridge is the creation of a Common Object Request Broker Architecture (CORBA) layer over Link 16. In addition, application of quality of service techniques and resource management technologies will ensure the timely exchange and processing of mission critical information by both attack and command nodes in even the most time-sensitive situations.     

Solid-state integrating detectors as an indicator of biological doses from HZE particles.

For interpretation of results obtained in future biological experiments in the International Space Station (ISS), biologically equivalent doses have to be determined using small-scale detectors without disturbing the surrounding radiation field. The detectors should be lightweight, stable, safe, and simple in handling. Solid-state integrating detectors (SSID) can satisfy these requirements. This paper demonstrates that combination of SSID such as thermoluminescence dosimeters and radiophotoluminescence glasses can be practically used for the evaluation of biologically equivalent doses. Statistical errors (type-A uncertainty) of this method will be satisfactorily small relative to those generally observed in biological responses. Permissible levels of systematic errors (type-B uncertainty) depend on dosimetry purposes (most-probable or conventional) and variability of biological responses.