• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.3
• /
• pp.93-98
• /
• 2005

STSAT-2 will be launched on December 2007 by the first Korean launch vehicle KSLV-1, and its one of the main instruments is DREAM (Dual Channel Radio Frequency and Environment Atmosphere Monitoring) which detects a signal for atmosphere from the Earth by using micro-wave signal. The STSAT-2 has many units for technology demonstration such as FDSS (Fine Digital Sun Sensor) and DHST (Dual Head Star Tracker) including PPT (Pulsed Plasma Thruster) for attitude control and momentum dumping in the space. In this paper, the power budget analysis for STSAT-2 will be studied and provided for supporting the whole mission life time during the mission of its spacecraft.

• Aerospace Engineering and Technology
• /
• v.2 no.2
• /
• pp.45-49
• /
• 2003

A Bake-Out test for STSAT-1 FM(Flight Model) was performed in a Bake-Out Chamber at SITC(Satellite Integration & Test Center) in KARI(Korea Aerospace Research Institute). The purpose of this test is to measure and analyze the outgassing rate to affect the optical equipment(FIMS) and to eliminate contaminants through the high temperature bake-out. This Bake-Out test is composed of three parts which are honeycomb panels & harnesses(Batch 1), an assembled satellite(Batch 2), and a disassembled satellite(Batch 3). For each test, quantitative and qualitative measurements and analysis were performed using TQCM(Thermoelectric Quartz Crystal Microbalance) and RGA(Residual Gas Analyzer.)

• Satellite Communications and Space Industry
• /
• v.13 no.1 s.28
• /
• pp.108-117
• /
• 2006

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.1
• /
• pp.80-86
• /
• 2010

This paper describes the development result of S-band Transmitter of STSAT-3 by satellite research center(SaTReC), KAIST. STSAT-3 has two kinds of communication channels, S- band for Telemetry & Command and X-band for mission payload. S-band Transmiiter(STX) consist of modulator, frequency synthesizer, power amp and DC/DC converter. The modulation scheme of STX is FSK(Frequency Shift Keying). The interface between spacecraft OBC and STX is RS-422. The STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under 1E-5. The Test of STX is completed successfully such as functional Test and environmental(vibration, thermal vacuum) Test.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.10
• /
• pp.10-16
• /
• 2008

Generally, the satellite circling round in a low orbit goes through Van Allen belt connecting with the magnetic fold, in which electronic components are easily damaged and shortened by charged particles moving in a cycle between the South Pole and the North Pole. In particular, Single Event Upset(SEU) by radiation could cause electronic device on satellite to malfunction. Based on the idea mentioned above, this study considersabout SEU effect on the On-board Computer(OBC) of STSAT-1 in the space environment radiation, and shows algorithm to cope with SEUs. In this experiment, it also is shown that the repetitive memory read/write operation called memory wash is needed to prevent the accumulation of SEUs and the choice for the period of memory wash is examined. In conclusion, it is expected that this research not only contributes to understand low capacity of On-board Computer(OBC) on Low Earth Orbit satellite(LEOS) and SaTReC Technology satellite(STSAT) series, but also makes good use of each module development of Korea Multi-Purpose Satellite(COMPSAT) series.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.12
• /
• pp.1174-1180
• /
• 2011

Field Programmable Gate Array(FPGA)s are replacing traditional integrated circuits for space applications due to their lower development cost as well as reconfigurability. However, they are very sensitive to single event upset (SEU) caused by space radiation environment. In order to mitigate the SEU, on-board computer of STSAT-3 employed a triple modular redundancy(TMR) and scrubbing scheme. Experimental results showed that upset threshold energy was improved from 10.6 MeV to 20.3 MeV when the TMR and the scrubbing were applied to the on-board computer. Combining the experimental results with the orbit simulation results, calculated bit-flip rate of on-board computer is 1.23 bit-flips/day assuming in the worst case of STSAT-3 orbit.

• Journal of Astronomy and Space Sciences
• /
• v.25 no.4
• /
• pp.435-444
• /
• 2008

High energy charged particles are trapped by geomagnetic field in the region named Van Allen Belt. These particles can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-l) was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-l orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-l solar cell degradation was caused by energetic protons which energy is about 700keV to 1.5MeV. Our result can be applied to estimate solar cell conditions of other satellites.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.20 no.4
• /
• pp.1-6
• /
• 2012

The accurate information of mass properties is required for the precise control of the spacecraft. The mass properties, mass and inertia, are changeable by some reasons such as consumption of propellant, deployment of solar panel, sloshing, environmental effect, etc. The gyro-based attitude data including noise and bias reduces the control accuracy so it needs to be compensated for improvement. This paper introduces a real-time inertia estimation method for the attitude determination of STSAT-3, Korea Science Technology Satellite. In this method we first filter the gyro noise with the Extended Kalman Filter(EKF), and then estimate the moment of inertia by using the filtered data from the EKF based on the Recursive Least Square(RLS).

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.6
• /
• pp.553-558
• /
• 2011

This paper describes the development and test result of S-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels, S-band for Telemetry & Command and X-band for mission data. S-band Transmitter(STX) functionally made of modulator, frequency synthesizer, power amp and DC/DC converter. The transmission data is modulated by FSK(Frequency Shift Keying) and the interface between spacecraft sub-module and STX is RS-422 standard method. The FM STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under $1{\times}10^{-5}$ which meets the specification respectively. The FM STX is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.10
• /
• pp.992-997
• /
• 2010

The Propulsion Control Module(PCM) of Hall-thruster Propulsion System(HPS) for Science and Technology Satellite-3 (STSAT-3) has the flow control accuracy of less than ${\pm}$3% and the pressure control accuracy of less than ${\pm}$5%. The pressure controller adjusts pressure around the set point by using a Proportional Flow Control Valve (PFCV) and a high pressure transducer, while the flow controller regulates the flow rate using PFCV and the anode current telemetry of the Hall Thruster. The controllers are chosen as the Proportional and Integral(PI) type, and the PI gains are tuned based on the Matlab simulations. The result of the PCM test had the flow control accuracy of less than ${\pm}$1.87% and the pressure control accuracy of less than ${\pm}$5%. This paper describes the design, realization, and performance test results of the PCM.