Suk-Jin Kang

Development of the HAUSAT-2 nanosatellite for low-cost technology demonstration

This paper addresses the development and design of the HAUSAT-2 (Hankuk Aviation University SATellite-2) which is nano class ultra-small satellite, being developed by SSRL (Space System Research Lab.) of Hankuk Aviation University. As a spin-off result, the HAUSAT-2 project can offer graduate and undergraduate students great opportunities to be able to understand the satellite design process, analysis, manufacturing, assembly, integration, test, launch and operation and also provides practical experience as a team member. The main mission objectives of the HAUSAT-2 satellite are to study the scope of activities and ecology of animals using Animal Tracking System (ATS) and collect the space information data from Electric Plasma Probe (EPP) as a space science payload. The HAUSAT-2 satellite is being designed to be compatible with a LEO with attitude 650 /spl sim/ 800 km sun synchronous orbit during design mission life which is expected to be 2 years. The HAUSAT-2 is a nano-satellite which is less than 25kg of mass with 30 cm /spl times/ 30 cm /spl times/ 38 cm hexahedron configuration. The three-axis stabilization is being implemented with pitch bias momentum method. Sun sensors and magnetometer manufactured by SSRL will provide attitude.

HAUSAT-2 nanosatellite ADCS performance analysis and commissioning

The HAUSAT-2 is a 25kg class nanosatellite which is being developed by graduate students at the Space System Research Laboratory (SSRL). The HAUSAT-2 implements a pitch bias momentum method for 3-axis stabilization, consisting of one momentum wheel in pitch axis and 3-axis magnetic torquers. 2-axis sun sensors, a 3-axis magnetometer, and a star tracker are used to determine the attitude. This paper describes two primary attitude control modes and control performances to perform the following functions: 1) initial acquisition (initial attitude acquisition mode), 2) 3-axis stabilization (mission mode). In addition to two operation modes, momentum wheel start-up method was also simulated using MATLAB. For detumbling the satellite, the initial mode uses a momentum wheel and magnetic torquers with B-dot control law. The mission mode also uses a momentum wheel and magnetic torquers to maintain 3-axis stabilization. A momentum wheel will have to be started from rest before it is fully operated. If the wheel speed is suddenly increased to nominal wheel RPM, the angular momentum produced can cause instability to satellites body. In this paper, effective wheel start-up method of ultra-small satellite equipped with momentum wheel and magnetic torquers has been studied. Also, a momentum dumping method using magnetic torquers was considered.

DEVELOPMENT OF SYSTEM ENGINEERING DESIGN TOOL (SEDT) FOR SMALL SATELLITE CONCEPTUAL DESIGN

Although satellites are getting smaller and the development duration is getting shorter, it still takes a long time to conduct a satellite conceptual design. The System Engineering Design Tool (SEDT) has been developed to effectively and efficiently design small satellites, which are in the range between 10kg (nanosatellite) and 200kg (microsatellite) to minimize the amount of labor involved. The present SEDT consists of five design blocks and has some characteristics different from system engineering tools previously developed. First of all, it adopts top-down design methodology which induces the architecture of distributed design. SEDT has also implemented the subsystem design process which is connected in series. It enables the design order of satellite system based on design parameters of satellite database constructed from over 200 small satellites launched between 1990 and 2004, which can improve the data reliability as a design reference. SEDT incorporates system budgets, mass and power, as verification parameters, and some characteristic trend equations. SEDT can do the conceptual system/subsystem design, analyze the design output, and predict the ROM development cost in accordance with user’s requirements. Specially, the SEDT implements GUI to provide convenience to the users.

Micro-Thruster Performance Measurement System Development Using Optical Sensors

A new method for measuring the performance of a micro-thruster is suggested in this paper. A few thrust stands have been developed for measuring micro-level thrusts. This paper describes a different measurement method that can minimize the calibration involved in the measurements, while providing the capability of directly measuring the produced minimum impulse bit directly. The underlying theory and the theoretical background for the measurement mechanism are described here. The theory and method is verified using a computer simulation, and the result is given in this paper. The theory has also been tested on an actual hardware. Although this hardware is a prototype, developed for proof-of-concept analysis, satisfactory results have been obtained.

Development and Performance Validation of Integrated Bus Electronic Unit for Small Satellite

Unlike large satellites, small satellites, such as nanosatellite and microsatellite, can provide a limited interior space for components mounting. In order to mitigate this issue, the compact Bus Electronic Unit(BEU) that integrates satellite electronic modules, combining most of bus subsystems and payload electronic modules into one unit, has been developed for HAUSAT-2 nanosatellite. This paper addresses the design and environmental test result analyses of BEU. The vibration and thermal vacuum tests were conducted at qualification level for the verification of design margin of newly developed BEU. The performance of individual electronic subsystem modules has been verified through performance tests before and after the qualification tests. It was confirmed that the natural frequency of BEU satisfies the design stiffness requirement without structural damage in the vibration test. Thermal analysis results were also almost consistent with test results through modified thermal analysis modeling.