Seoul National University Launches Twin Satellites From International Space Station

The QB50 Project.

After what months and months of delays, further delays and launcher changes which screwed a lot of the initial designs, Seoul National University (SNU)'s two participating CubeSats [What the hell is a CubeSat? HERE] in the QB50 project [QB50? HERE] was finally launched on April 18, 2017 as a payload to International Space Station (ISS) and then deployed from ISS soon there after by NanoRacks. The fact that it's in space orbiting at roughly 400km in Low Earth Orbit (LEO) and not in the CubeSat Research Center at building 36 of Seoul National University is frankly, crazy. 

The two satellites dubbed as KR-02 and KR-03, carries identical FIPEX sensors [Learn more HERE] as its primary payload. The payload collects data on the chemical composition of lower and mid thermosphere. While the sensor was not designed by SNU, most of the system that supported that was built in house. The slide below tries to explain further about the primary mission. 

A succinct version shows an overview of SNUSAT-1/1b presented at University of Tokyo in 2016. At that time, the team was working on the Proto-Flight Model. 

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Click to enlarge

DESIGN

The FIPEX sensor sits on top

KR-02 and KR-03 during Flight Model (FM) Assembly, Integration and Testing (AIT)

The Solidworks rendering shown is an old version, however, the core subsystem have remained constant

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The primary payload, the FIPEX sensor module, is placed on the top of the 2U CubeSat

KR-03 Placed inside a pod before undergoing vibration testing

DESIGN PROCESS

Laying out the ground work before AIT

Initially, Bread Board Modelling is done for proof of concept

After BBM, we then proceed to creating the PCBs. Shown here is the IFBATT (Battery Board)

All the designs were done with PADS

SNUSAT-1/1b had several Interface Boards (IF) to connect between different subsystems

After preparation of the PCB, all the components were hand soldered and checked

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Preping for environmental testing at SaTRec, KAIST, South Korea

SNUSAT-1 undergoes solar panel voltage test after vibration testing

Deployment test during thermal vacuum cycle tests

Ground Station

Since Seoul National University's CubeSat is now launched, the current SNUSAT team will be working on the ground station to downlink and uplink data. SNU's ground station is summarized in the next pic.

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The antenna seen here is a cross-Yagi antenna which consists of two interleaved Yagi-Uda arrays each placed perpendicular to each other. This setup ensures that there is a proper phase delay between two arrays while achieving circular polarization. The antenna rotator is a Yeasu elevation-azimuth dual controller that can lock-on to any satellite that passes overhead. Communication time per pass for SNUSAT-1 is estimated to be 10 minutes.

A Very Special Tribute 

Ji (center) smiles after a very hard nights work

SNUSAT-1/1b would not have been 400km in space, had it not been for the work ethic and diligence of my lab chief, mentor and humongous bully, Ji Hyun Park. He single-handedly made SNUSAT project possible while loosing 50% of his hair and drinking 1kL wine. In all honesty, I was just there to pass him the screw driver the whole time. What a monster. 

Special thanks to previous SNUSAT-1 team mate, Jaeyoung Lim for all the support along the way. Hope you are crossing your fingers as I am.