Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Utah State University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 15001 - 15030 of 17118

Full-Text Articles in Entire DC Network

A Flexible Object Oriented Spacecraft Operating System (Fos), Dave Ladouceur Aug 1990

A Flexible Object Oriented Spacecraft Operating System (Fos), Dave Ladouceur

Small Satellite Conference

Satellite Operating Software has traditionally been highly specialized custom software which operates one satellite according to deterministic rules. Software changes are usually accomplished with a complete reload from the ground, and performing patches require explicit knowledge of memory maps, variable locations, etc. and can often result in long term satellite down times. As computer, sensor and communication technology increases, more and more of the computing, routing and decision functions of small satellite systems are occurring onboard, and a need exists for adaptable flexible software. The object oriented approach to satellite operating systems provides a malleable system, resilient to failure, distributable …

Go to article

An Innovative On-Board Processor For Lightsats, R.M. Henshaw, B.W. Ballard, J.R. Hayes, D.A. Lohr Aug 1990

An Innovative On-Board Processor For Lightsats, R.M. Henshaw, B.W. Ballard, J.R. Hayes, D.A. Lohr

Small Satellite Conference

The Applied Physics Laboratory has developed a flightworthy custom microprocessor that increases capability and reduces development costs of lightsat science instruments. This device, which APL calls the FRISC (Forth Reduced Instruction Set Computer), directly executes the high level language called Forth, which is ideally suited to the multitasking control and data processing environment of a spaceborne instrument processor. The FRlSC (which is available commercially as the SC32) will be flown as the on-board processor in the Magnetic Field Experiment on the Swedish Space Corporations’ Freja satellite. APL has achieved a significant increase in on-board processing capability with no increase in …

Go to article

Fault Tolerant Techniques For Spacecraft Data Recorders, Scott Anderson Aug 1990

Fault Tolerant Techniques For Spacecraft Data Recorders, Scott Anderson

Small Satellite Conference

This paper presents the techniques for improving system reliability which SEAKR Engineering employs in the design of their spacecraft solid state data recorders. Briefly, these techniques include Hamming code error correction, periodic memory scrubbing, latch-up protection, excessive capacity, redundant power supplies/control/bus circuits, microcode protection, and shielding.

Go to article

In-Orbit Radiation Effects Monitoring On The Uosat Satellites, Craig Underwood Aug 1990

In-Orbit Radiation Effects Monitoring On The Uosat Satellites, Craig Underwood

Small Satellite Conference

Since the summer of 1988, radiation effects, in particular single event upset (SEU) phenomena, have been monitored in the three mass semiconductor memory systems onboard the University of Surrey's UoSAT-2 satellite, which is in a 700 km, near-polar low-Earth orbit. Almost 5000 events have now been logged by the spacecraft, and these have been assembled into a database for analysis by ground-based software. This software has allowed the SEU sensitivity of different device types to be analyzed, and the relative performance of the Mostek 4116, Texas 4416 NMOS DRAMs, the Toshiba TC5516, Harris 6564 and 6516, and the Hitachi 6264 …

Go to article

"Lone Star," A Small Communication Satellite For Texas, J.P. Andrews, N. Eaker, J.D. King Aug 1990

"Lone Star," A Small Communication Satellite For Texas, J.P. Andrews, N. Eaker, J.D. King

Small Satellite Conference

The Texas State Legislature has passed a bill recommending that the state examine the feasibility of developing a "home grown" satellite for communications applications. Such a satellite would be built in Texas by a state, industry and university consortium with the intent that it be launched by a Texas built launch vehicle. This paper reports on a quick look design and trade-off study that was performed to determine the characteristics and possible configurations that such a small satellite system would have. The communications link budget is discussed and used to define the communications payload that would be carried by the …

Go to article

Design Of An Electrically-Propelled Asteroid Rendezvous Probe Launched As A Secondary Payload, Ralph Lorenz Aug 1990

Design Of An Electrically-Propelled Asteroid Rendezvous Probe Launched As A Secondary Payload, Ralph Lorenz

Small Satellite Conference

This paper summarises a design study undertaken as a final year project for the author’s B.Eng in Aerospace Systems Engineering. A spacecraft design is outlined for a vehicle to perform a rendezvous with a near earth asteroid after being launched as a secondary payload into Geosynchronous Transfer Orbit. The 380 kg (dry) spacecraft would use a bipropellant chemical propulsion system to manoeuvre in, and escape from Earth orbit. Interplanetary maneuvering would be accomplished with an ion propulsion system.

Go to article

Microspacecraft And Earth Observation: The Electrical Field (Elf) Measurement Project, F.J. Redd, T.A. Olsen Aug 1990

Microspacecraft And Earth Observation: The Electrical Field (Elf) Measurement Project, F.J. Redd, T.A. Olsen

Small Satellite Conference

Past attempts to map the earth's electrical field have been severely limited by the lack of simultaneous global measurements. Previous measurements have been made by sounding rocket and satellite borne sensors, but these measurements have covered only singular points in the field. These satellite observations are augmented by ground radar (incoherent scatter) plasma drift measurements; however, only six ground-based installations are producing such local electrical field maps. The expansion of this ground-based radar network to meet a global objective is politically and financially impossible. Global electrical field maps constructed by forcing mathematically formulated models to fit this limited set of …

Go to article

Cheap Auroral Tomographical System (Cats), Dean Garlick, Andrew Goldfinger Aug 1990

Cheap Auroral Tomographical System (Cats), Dean Garlick, Andrew Goldfinger

Small Satellite Conference

The Cheap Auroral Tomographical System (CATS) consists of a large constellation of small, disposable satellites in a near polar orbit. CATS is designed to collect stereoscopic views of the earth environment that will be used for tomographical and earth environmental research. Each satellite will be identical and constructed of high-grade commercial parts, thus significantly reducing the cost of design, fabrication and components. The CATS constellation will be a significant step toward the demonstration and validation of the capability to develop, deploy and operate a proliferated system of small, inexpensive satellites. Additionally, CATS will gather valuable scientific data from the earth …

Go to article

Attitude Control Of A Small Spacecraft In An Elliptical Orbit, K.A. Ryden, A.J. Markwell Aug 1990

Attitude Control Of A Small Spacecraft In An Elliptical Orbit, K.A. Ryden, A.J. Markwell

Small Satellite Conference

A small research satellite is being developed by the Royal Aerospace Establishment, UK, for the purpose of in-orbit technology research. The satellite is planned for launch on an Ariane 4 mission into the severe environment of a geostationary transfer orbit in which it will remain. This paper addresses the challenges which have arisen in designing an attitude control system for a satellite in this unusual orbit. The paper includes discussion of how recovery from an initial tumbling state is to be performed why spin stabilization has been selected, how magnetorquers can be used to control the attitude and finally the …

Go to article

Small Satellite Reaction Wheel Optimization, Ted Michaelis Aug 1990

Small Satellite Reaction Wheel Optimization, Ted Michaelis

Small Satellite Conference

The very "smallness" of small satellites mandates mass minimization. This paper addresses minimization of overall reaction wheel mass, including the incremental mass of the power subsystem needed to support the reaction wheel. The results are applicable to a wide range of wheel sizes and are suitable for optimization at the configuration level. For an average momentum and torque operating point, the minimization process yields wheel radius and angular velocity, as well as, the masses associated with the motor, wheel, housing, and power subsystems. Only four parameters are needed: the power supply mass penalty, a generalized motor constant, the wheel form …

Go to article

Magnetic Attitude Control System For Spinning Small Spacecraft, Parimal Pal, Vaughn Selby Aug 1990

Magnetic Attitude Control System For Spinning Small Spacecraft, Parimal Pal, Vaughn Selby

Small Satellite Conference

A magnetic Attitude Control Subsystem (ACS) designed for minimum power weight, and cost is presented. The ACS subsystem was designed and built by ITHACO for the Small Communications Satellite Cluster (SCSC), integrated by Defense Systems Incorporated for the Defense Advanced Research Projects Agency. The basic spacecraft configuration is a flat cylinder, having a mass of 22.7 Kg with a diameter of 47.2 cm and 17.0 cm height. Hardware for the ACS design includes a two-axis magnetometer, two TORQRODs, a Horizon Crossing Indicator and the host microprocessor. During acquisition mode, the ACS spins up and stabilizes the spacecraft with a spin …

Go to article

Spaces - An Integrated Software Approach For Attitude Determination, Control And Pointing Systems Analysis, James Billing-Ross, Douglas Havenhill Aug 1990

Spaces - An Integrated Software Approach For Attitude Determination, Control And Pointing Systems Analysis, James Billing-Ross, Douglas Havenhill

Small Satellite Conference

The recent success of the Pegasus small satellite launch system by Orbital Sciences Corporation foreshadows radical changes to the satellite industry comparable to those which occurred in the computer industry when personal computers became commercially available alternatives to mainframes. In order to support low cost, fixed price contracts for small commercial satellites, engineering design cycles for satellites and satellite subsystems will have to be shortened, and accomplished with fewer staff to meet more stringent cost and schedule goals. To accomplish this, better design tools must be made available which will allow the mission analysis, requirements analysis, and other systems engineering …

Go to article

Attitude Determination And Control For The Multi-Mission Space Payload Platform (Spp), Charles Benet, John Stetson, Jr. Aug 1990

Attitude Determination And Control For The Multi-Mission Space Payload Platform (Spp), Charles Benet, John Stetson, Jr.

Small Satellite Conference

The first artificial satellite, Sputnik, was a "smallsat" of sort with its 58 cm. diameter and mass of just under 84 kg. Since then, design trends have produced progressively larger spacecraft tracking the launch vehicle throw capabilities. This approach, however, is being challenged today and, although large satellites will continue to meet global requirements cost effectively, there is a need to accommodate specific payloads with smaller spacecraft buses. The economy of scale that called for larger satellites in the past, is now focusing on a multi-mission design approach. A general purpose spacecraft bus can be designed to support a wide …

Go to article

Small Payload Opportunities Aboard Soviet Launch Vehicles, William Wirin, Yuri Solomonov Aug 1990

Small Payload Opportunities Aboard Soviet Launch Vehicles, William Wirin, Yuri Solomonov

Small Satellite Conference

The Space Commerce Corporation of the U.S. and Technopribor of the Soviet Union have agreed to develop jointly and market a new commercial mobile launch vehicle derived from Soviet SS-20 medium-range missile technology. The Soviets have indicated they could produce 300 launchers within a five-year period following a go-ahead decision. The launcher could be employed for commercial payloads or scientific research, including materials processing experiments. President Gorbachev reiterated in his speech at Stanford University on June 4, 1990 the commitment of the Soviet Union to convert military armaments to peaceful commercial purposes. He recognized the requirement to develop international legal …

Go to article

Space Qualification Proceeds On The Common Data Link Program, Major Curt Osterheld, Doug Bowen, Susan Opp Aug 1990

Space Qualification Proceeds On The Common Data Link Program, Major Curt Osterheld, Doug Bowen, Susan Opp

Small Satellite Conference

A modular Communication, Command, and Control (C3) architecture has been developed for use in a variety of Department of Defense (DoD) applications by the Office of the Secretary of the Air Force/Defense Support Project Office (OSAF/DSPO). The C3 architecture is implemented under the direction of the SAF/DSPO's Common Data Links Program Office using government defined and controlled common modules. This set of common modules is now being qualified for space applications. The family of common modules provide the building block to satisfy a wide range of unique operational requirements while achieving commonality, tri-service interoperability, multi-system connectivity, and a flexible baseline …

Go to article

Field Command Of A Tactical Satellite System, Ron Turner, Stephen Hopkins Aug 1990

Field Command Of A Tactical Satellite System, Ron Turner, Stephen Hopkins

Small Satellite Conference

One way to ensure tactical satellite systems remain fully responsive to a field commander's needs would be to place all command and control aspects of the system under direct field control. This paper presents the results of a study to evaluate the feasibility of field command of a notional tactical imaging satellite system. The study indicates that such a system is feasible. A satellite constellation can be designed to provide the field commander with significant, timely, tactical data. The hardware is available, or will be within the near term, that enables field command and control facilities manned by a team …

Go to article

A Multi-User Carrier Structure For Deploying Pegasus-Launched Micro-Satellites, J.A. King, N.J. Beidleman, P.M. Stoltz Aug 1990

A Multi-User Carrier Structure For Deploying Pegasus-Launched Micro-Satellites, J.A. King, N.J. Beidleman, P.M. Stoltz

Small Satellite Conference

Now that the viability of the Pegasus air launched booster has been demonstrated, it is possible, and indeed appropriate, to devise methods for exploiting the launcher so that it can launch multiple micro-satellites. Such spacecraft may be launched for a single user, or the capacity of a single launcher may be divided among multiple users. In fact, not all of the satellites on a single launch need to be placed into the same orbit. This paper describes a concept, developed by OSC, to place multiple micro-satellites into various orbits using a single Pegasus launch vehicle. The concept makes use of …

Go to article

Launch Options For Mars Network Missions Using Small Spacecraft, Walter Daniel Aug 1990

Launch Options For Mars Network Missions Using Small Spacecraft, Walter Daniel

Small Satellite Conference

The currently-planned Mars Global Network Mission calls for a Delta II launch to deploy spacecraft that will place small stations on the surface of the planet. This study of small launch vehicles revealed that the Taurus is more cost efficient than large launch vehicles such as the Delta II and Titan IV. The Taurus can launch 1092 lb into a Mars transfer orbit at a cost of $13,740/lb while the Delta 7925 can place 2350 Ib into the transfer orbit at $17,450/lb. Small vehicles such as the Scout G-l and Pegasus can place less than 300 Ib into the transfer …

Go to article

Webersat Operations And Experiment Results, Charles Bonsall, Keith Christensen, Stephen Jackson, Spencer Poff, Jeff Raetzke, Claude Smith, Robert Summers Aug 1990

Webersat Operations And Experiment Results, Charles Bonsall, Keith Christensen, Stephen Jackson, Spencer Poff, Jeff Raetzke, Claude Smith, Robert Summers

Small Satellite Conference

WEBERSAT, a 27 pound LEO satellite launched by the Ariane 40 on January 21, 1990 into an 800 Km polar orbit, carries several inexpensive payload experiments that were developed as a learning experience for engineering students at Weber State College. The experiments include a color CCD camera, a CCD light spectrometer, video flash digitizer, 1.26 GHz NTSC video uplink, micro-impact sensor, and optical horizon sensors. Operational command and control of the spacecraft and its payloads is performed by students in the School of Technology, from a ground station located on the WSC campus. Here, the students and their advisors monitor …

Go to article

The In-Orbit Performance Of Four Microsat Spacecraft, J.A. King, R. Mcgwier, H. Price, J. White Aug 1990

The In-Orbit Performance Of Four Microsat Spacecraft, J.A. King, R. Mcgwier, H. Price, J. White

Small Satellite Conference

On January 22, 1990, Ariane V-35 placed four Microsat spacecraft into orbit. The orbit achieved is nearly perfectly sun synchronous at 800 km altitude. The satellites, cubic structures measuring only 23 cm per side, were developed by the Radio Amateur Satellite Corporation of North America (AMSAT-NA). The time required to complete the project, from conception to delivery of the four satellites to Kourou, was exactly two years. Each satellite in orbit has a different mission and is performing in accordance with its intended design, although additional software is still being written to enhance the operating characteristics for each mission. This …

Go to article

Offeq – 2 Orbit And Attitude Flight Evaluation Report, Jerry Wittenstein, Haim Shyldkrot, Michael Grumer, Joseph Komem, Ophir Kubitski, Joseph Kronenfeld Aug 1990

Offeq – 2 Orbit And Attitude Flight Evaluation Report, Jerry Wittenstein, Haim Shyldkrot, Michael Grumer, Joseph Komem, Ophir Kubitski, Joseph Kronenfeld

Small Satellite Conference

Offeq-2, Israel's second research and development satellite, was inserted into an orbit of 214 km perigee altitude by 1570 km apogee altitude on April 3, 1990. Its primary mission was to further demonstrate IAI's satellite technology development and its ground station's ability to track the satellite, send it commands and receive its telemetry. The Offeq-2 satellite was expected to be on-orbit for about two to two and a half months (60 to 75 days), and actually was on orbit over three months (97 days). It was expected, due to the dynamic behavior of a spin stabilized satellite under the influence …

Go to article

Pegsat - First Pegasus Payload, Robert Pincus, Jack Pownell, James Rast Aug 1990

Pegsat - First Pegasus Payload, Robert Pincus, Jack Pownell, James Rast

Small Satellite Conference

Pegsat was designed, built and tested in slightly more than 6 months to meet the planned launch date for the first launch of the Pegasus vehicle. The primary objective of this multifunction spacecraft was to obtain environmental data from the Pegasus vehicle for use in designing future satellite busses. Taking full advantage of the opportunity, Pegsat also deployed a small Navy experimental satellite, and conducted scientific experiments over Northern Canada in support of the upcoming CRRES mission.

Go to article

Pegasus First Mission - Flight Results, Marty Mosier, Gary Harris, Bob Richards, Dan Rovner, Brent Carroll Aug 1990

Pegasus First Mission - Flight Results, Marty Mosier, Gary Harris, Bob Richards, Dan Rovner, Brent Carroll

Small Satellite Conference

On April 5, 1990, after release from the wing of a B-52 carrier aircraft over the Pacific ocean at an altitude of 43,198 ft, the three stage Pegasus solid propellant rocket successfully completed its maiden flight by injecting its 423 lb payload into a 273 X 370 nautical mile 94 degree inclination orbit. The first flight successfully achieved all mission objectives; validating Pegasus's unique air launched concept, the vehicle's design, as well as its straightforward ground processing, integration and test methods. This report summarizes the results of the first launch, including measured vs. predicted motor performance, drag and lift coefficients, …

Go to article

Cryo-Preparation And Planar Magnetron Sputtering For Low Temperature Scanning Electron Microscopy, T. Müller, P. Walther, C. Scheidegger, R. Reichelt, S. Müller, R. Guggenheim Aug 1990

Cryo-Preparation And Planar Magnetron Sputtering For Low Temperature Scanning Electron Microscopy, T. Müller, P. Walther, C. Scheidegger, R. Reichelt, S. Müller, R. Guggenheim

Scanning Microscopy

Cryo-preparation is a reliable technique for the structural investigation of food products in low temperature scanning electron microscopy (SEM). Artifacts, such as, the segregation of water/non-water ingredients, occur during the freezing process by the crystallization of ice; they can be helpful for correct interpretation of visualized details, e.g., the detection of water containing compartments. The size of the segregation structures depends on water concentration and specimen thickness. The condensation of water vapor (ice contamination) is influenced by the specimen temperature and the partial pressure of the water inside the vacuum system. Furthermore, the evaporation (sublimation, etching) of specimen water can …

Go to article

Ministar: A Small Spacecraft For Geo Missions, G. Barresi, G. Rondinelli Aug 1990

Ministar: A Small Spacecraft For Geo Missions, G. Barresi, G. Rondinelli

Small Satellite Conference

This paper provides the information of the conceptual design of MINISTAR and presents the major features of this small spacecraft, able to support geostationary missions for satellite communications. MINISTAR is a sun pointing satellite, with despun antenna provided with momentum wheels to achieve gyroscopic stiffness along the pitch axis, maintained orthogonal to the geosynchronous orbit. Thrusters supply the attitude stabilization for yaw and roll axes and station keeping maneuvers. An unified propulsion system is adopted, with helium pressurized bipropellant. The system makes use of monomethyhl hydrazine as propellant and nitrogen tetroxide as oxidizer. Large autonomy is provided by the on-board …

Go to article

The Bremsat Phase-Modulated Communications Link, Don Lefevre Aug 1990

The Bremsat Phase-Modulated Communications Link, Don Lefevre

Small Satellite Conference

BREMSAT is a small scientific satellite being constructed by the west German Zentrum fur angewandte Raumfahrttechnologie und Mikrogravitation (ZARM), at Bremen University. BREMSAT's payload consists of five scientific experiment packages. The satellite is scheduled for Get-Away-Special (GAS) Canister launch during the German D-2 shuttle mission in March 1992. Cynetics Corporation is constructing the TT&C link for the satellite, using its standard CMX9600 modem. This modem is the result of Cynetics' development program for phase-modulated (PM) communications systems for small satellites. The CMX9600 is a 9.6 KC/s, Bi-Phase Shift Keyed (BPSK) modem using a 70-MHz IF and synchronous matched-filter detection. As …

Go to article

Store-And-Forward Message Relay Using Microsatellites: The Uosat-3 Pacsat Communications Payload, Jeffrey Ward Aug 1990

Store-And-Forward Message Relay Using Microsatellites: The Uosat-3 Pacsat Communications Payload, Jeffrey Ward

Small Satellite Conference

One of the most promising applications for small satellites in the 10-50 kg class is store-and-forward message relay. A single store-and-forward message relay satellite in a polar orbit can provide a global communications network carrying electronic mail, digitized voice, images or computer data. With appropriate choice of link characteristics, small, low cost ground terminals can be used. When designing an inexpensive microsatellite system to provide store-and-forward communications to small ground terminals, the engineer must challenge the standard assumptions made concerning such things as link frequency, modulation techniques, error-control, and multiple-access arbitration. Beginning with experiments on its UoSAT-2 satellite, the Spacecraft …

Go to article

User-Oriented Performance Measurements Of The Amsat-Na Microsat, Robert Diersing Aug 1990

User-Oriented Performance Measurements Of The Amsat-Na Microsat, Robert Diersing

Small Satellite Conference

A preliminary set of user-oriented performance measurements has been conducted using the AMSAT-NA PACSAT-1, and to a lesser degree, the AMSAT-LU LUSAT-1 Microsats. These preliminary measurements have been carried out by exchanging files and commands between two separate ground stations. During some of the tests a third station was used to monitor the satellite downlink independent of the stations engaged in the communications exchange. The monitored frames were captured and examined as an aid in determining the effective data rate and response time as observed by the end user. The tests have been an attempt to determine approximately what performance …

Go to article

Laser Payloads On Small Satellites, L.S. Lingvay, A.P. Bowman, A.S. Wallace Aug 1990

Laser Payloads On Small Satellites, L.S. Lingvay, A.P. Bowman, A.S. Wallace

Small Satellite Conference

Laser payloads on satellites have the ability to enhance our communications capabilities and information gathering power from space. Implementation of lasers to Lightsats provides one method to assess the effectiveness of these technologies at reduced risk. This paper will focus on the main applications of lasers in space and how laser systems may be adapted to the Lightsat environment. This will include a discussion of the different types of lasers, which types are suitable for space based payloads, and which of these is suitable for what types of applications. Included in this discussion will be the selection criteria based on …

Go to article

Advanced Ehf Technologies For Lightweight Augmentation / Restoration Communications Satellites, Dean Kolba, William Greenberg, David Mcelroy, Marilyn Semprucci Aug 1990

Advanced Ehf Technologies For Lightweight Augmentation / Restoration Communications Satellites, Dean Kolba, William Greenberg, David Mcelroy, Marilyn Semprucci

Small Satellite Conference

Small EHF satellites can significantly complement the anti-jam service provided by basic EHF MILSATCOM space segments. Mobile/survivable launch vehicles with rapid launch preparations can be utilized to responsively deploy these small satellites into high altitude elliptical or circular orbits. From such orbits, only a few satellites are needed to provide high duty cycle coverage of a critical area. The communications capabilities provided by these EHF payloads can range from low data rate services (75 to 2400 bps per channel) to high data rate links (10 Mbps or more per link) depending on the payload configuration. Through the use of EHF …

Go to article

First Prev Next Last