I I THE AVATAR SMALL SPACECRAFT SYSTEM Joseph A. LeBlanc, President I American Microsat Inc. American Microsat president Joseph A. I LeBlanc will present the AVATAR Small Spacecraft System. The AVATAR Small Spacecraft System consists of the AVATAR I satellite modules and the ground control and data collection facility. The AVATAR spacecraft is comprised of I modules containing specific mission subsystems that are designed to work together or independently to satisfy I mission requirements. Four modules provide payload space, control, propulsion and three axis stabilization. The different modules (described below) I and the customer launch options will be discussed separately during the I presentation. Common Services Module: The Common Services Module houses the spacecraft I computer, the TT&C communications equipment, the attitude determination sensors, the spacecraft batteries, the power supply, and other optional I subsystems. Propulsion Module: The propulsion module I consists of thrusters and propellant stored in spherical tanks to maneuver the AVATAR satellite in orbit. Both cold gas and hydrazine systems are available. I Three Axis Stabilization Module: The three axis stabilization module contains the subsystems needed for high-resolution I three axis attitude determination and control. I Payload Module: The payload module houses the customer payload. The dimensions of the payload module vary, depending on specific payload I requirements. Payloads ranging from one to two hundred kilograms in mass can be I carried. I I I I I THE AVATAR SPACECRAFT SYSTEM I The founders of the American Microsat corporation saw the I need for a low-cost, small spacecraft system for commercial, industrial and institutional applications. Realizing that a reliably designed small spacecraft system could be built utilizing available off-the-shelf I components, they committed themselves to producing the best small spacecraft system possible. The result is the AVATAR Spacecraft System a versatile modularly designed I satellite system suitable for a wide range of applications. In planning the AVATAR Small Spacecraft system, American I Microsat designed it for the commercial market with affordability and capability in mind. The emphasis is placed on obtaining flight proven components, but without I the burdensome and expensive process of developing and certifying DOD-NASA compliance. As manufacturers were not about to do a complete redesign, the "commercial grade" components obtained by American Microsat are almost I identical to the "milspec" version. This approach eliminates much of the production costs and maximizes price performance. I The AVATAR Small Spacecraft system consists of the AVATAR modular bus, and the ground station control and data I collection facility. American Microsat provides Telemetry, Tracking & Commanding (TT&C) services as well as data collection services, or will provide assistance to the customers preferring to do their own data collection, to I include ground station design and construction. Overall, the AVATAR Small Spacecraft system is capable of I handling from five pounds to five hundred pounds of customer payload for any orbital altitude, inclination, and eccentricity desired. continuous electrical power ranges from 8 watts up to four hundred watts and is provided by a I combination of solar panel modules and rechargeable storage batteries. A variety of passive and active attitude control systems are available for low, medium, and high I resolution pointing applications. Vehicles can be spin stabilized from two rpm up to eighty rpm with better than one degree resolution, and three axis stabilized with five I degree, one degree, or 0.01 degree resolutions. I I I I The AVATAR spacecraft is comprised of modules containing mission optional subsystems that are designed to work together or independently to satisfy mission requirements. Four different modules provide payload space, common I services, propulsion capabilities, and high resolution three axis stabilization. A basic AVATAR satellite will consist of two modules, the common services module and the I payload module. The propulsion and high resolution three axis stabilization modules would be added as needed. I All the modules (except the payload module) are housed inside the AVATAR Standard Structural Shell. The AVATAR Standard Structural Shell· is an aluminum alloy right hexagonal cylinder measuring 11 inches high and 22 inches I across. Each of the shell sides is 11 inches by 11 inches and is coated with a substance to prevent oxidation even in space. Use of the Avatar Standard Structural Shell reduces I manufacturing and integration costs and allows for concealment of spacecraft components to meet export control requirements. I By utilizing this modular concept, the customer can select the capability required for a specific application. The modules, designed to integrate effectively, are brought I together to complete the spacecraft with minimum additional engineering and cost. American Microsat believes innovative design and assembly procedures such as this will I greatly reduce the total spacecraft system price. The American Microsat concept makes redesigns for each customer unnecessary_ Modules and subsystems are added as I needed to configure the AVATAR spacecraft for each application; much as an automobile is ordered with options I from the factory to suit each owner's needs. Some examples of the various AVATAR satellite configurations are given in the following figures. Figure 1 shows a Common Services Module outfitted with our 1 I degree resolution, Three Axis Stabilization system, and two AVATAR solar panels. Figure 2 is a spin stabilized configuration with the optional propulsion module above it. I Figure 3 is a fully outfitted AVATAR spacecraft with all four modules shown. I AVATAR I S design is compatible with all known expendable launch vehicles (ELV' s), such as the SCOUT booster (LTV Aerospace) for single launches, or the DELTA II booster for multiple launches. American Microsat constantly evaluates I newly developed expendable launch vehicles to ascertain their suitability for AVATAR launches. I I I I I I I Storage Battery Tip Mass I I I I Gravity Gradient Boom (not to scale) I I I Antennas I I Common Services Module with attitude sensors I and magnetic torquer rods installed I AVATAR I Payload GRAVITY GRADIENT MODEL t10dule I I FIGURE 1 I ------------------- Optional Propulsion Module Common Services Module outfitted for Spin Stabilized operations Spin Stabilization Boom (1 of 3) Payload Module AV ATA R SPIN SIN3lllZED FIGURE 2 Steerable Solar Array (1 of 2) Axis Stabilization Module Example of Payload Module FULLY EQUIPPED AVATAR SPACECRAFT FIGURE 3 ------------------- I I SUMMARY OF THE AVATAR SPACECRAFT MODULES AND THEIR CAPABILITIES I Common Services Module: The Common Services Module houses the spacecraft computer, the TT&C communications equipment, the attitude determination sensors, the spacecraft batteries, the power supply, and other control subsystems. I Solar panels and a variety of attitude control systems may be added to the exterior of this module as needed. The service module provides control and power for the I spacecraft and integrates the other spacecraft modules. Propulsion Module: The propulsion module consists of thrusters and propellant stored ln spherical tanks to I maneuver the AVATAR satellite in orbit. Both cold gas and hydrazine systems are available. Changes in attitude, spin rate, and orbit can be performed from the ground control I facility with minimum effort. The propulsion module also gives the AVATAR spacecraft access to higher orbits than is possible with an expendable launch vehicle alone, maximizing flexibility to satisfy just about any mission I profile. Three Axis Stabilization Module: The three axis I stabilization module contains the subsystems needed for high-resolution three axis attitude determination and control. Deployable, steerable solar arrays are also an I integral subsystem of this module, and provide maximum power for the spacecraft. Payload Module: The payload module houses the customer I payload. The dimensions of the payload module vary, depending on specific payload requirements. Payloads ranging from one to two hundred kilograms in mass can be I carried. Power and data/control interfaces are furnished from the service module to power the payload and to transfer data and provide control. By using a separate payload module, the customer can prepare the payload I independent of the other spacecraft modules, which provides anonymity and security for the customer. In fact, with the separate payload module, integration can occur in as little I as 30 days before launch and can be accomplished virtually anywhere. I AVATAR COMMON SERVICES MODULE The heart of any AVATAR spacecraft is the Common Services I Module. All subsystems common to most spacecraft are housed in this one module with the capability of adding several internal and external options. The AVATAR Common I Services Module houses the spacecraft computers, spacecraft batteries, power supply, Telemetry & Tracking and I Commanding equipment (includes the S-Band transmitters and I receivers), and other control subsystems. Internal options I include data tape recorders, attitude determination sensors, larger computer memory, and additional storage batteries. Solar panels, a gravity gradient boom, magnetic torquer rods, and spin stabilization booms may be added to I the exterior of this module as needed. The Common Services Module provides