Chapter 1 introduces the need for a satellite to house the MAPS instrument. The problem definition identifies the scope, boundaries, and relevant elements of the problem. Students at Virginia Tech modify an existing nanosatellite design, HokieSat, to fit the needs of the MAPS instrument. The following chapters outline the components pre-existing to HokieSat, and the detailed modifications made to each subsystem to arrive at a host satellite design.
Chapter 2 presents the VASCAT configuration and subsystem components. The configuration and the subsystem components are based on the HokieSat design. This chapter defines the subsystem designs and presents the analyses leading up to these designs. The satellite subsystems include the structure, the attitude determination and control system, the power system, the thermal system and the communications system.
The configuration of this satellite is based on an existing satellite design. HokieSat is a hexagonal nanosatellite with a major diameter of 18 inches and a height of 13.725 inches. It draws power from body-mounted solar cells covering approximately 80% of each side. HokieSat uses an electric propulsion system whose thrusters protrude from four sides of the structure. The HokieSat bus is made of a 6061-T6 aluminum alloy cut into an isogrid pattern. All eight sides are 0.23” thick isogrid. The six side panels are composite isogrid-skin. The 0.02” skin is bonded to the isogrid to form a 0.25” total thickness. All internal components are mounted to the interior of the six side panels and the two end panels. The external communications components are mounted to the exterior of the two end panels. Figure 2 and Figure 3 illustrate this configuration.8
The Virginia Satellite for Carbon-monoxide Analysis and Tabulation (VASCAT) is larger than HokieSat to accommodate added science instruments. Similarities between the two satellites’ components include the electronics box, the battery box, most communications equipment, and the magnetometer. This new satellite also houses the MAPS instrument, a digital camera, and some additional ADCS components. The VASCAT satellite does not require a propulsion system, as does HokieSat. The structure of the VASCAT deviates substantially from that of HokieSat. These detailed variations of all subsystems are discussed in the following sections.
Using knowledge of configuration and component properties, a mass budget is created to approximate the mass allocated for the structure. Table 3 is a breakdown of each subsystem’s mass. The sum of the masses of all components must be lower than the mass limit of the chosen launch vehicle. The subsystem masses are taken from component specifications and the structure mass is taken from mass properties calculations done in AutoCAD™.