In this study, a new idea for developing a space scale for measuring mass in a microgravity environment was proposed by using the inertial force properties of an object to measure its mass. The space scale detected the momentum change of the specimen and reference masses by using a load-cell sensor as the force transducer based on Newton’s laws of motion. In addition, the space scale calculated the specimen mass by comparing the inertial forces of the specimen and reference masses in the same acceleration field. By using this concept, a space scale with a capacity of 3 kg based on the law of momentum conservation was implemented and demonstrated under microgravity conditions onboard International Space Station (ISS) with an accuracy of ±1 g. By the performance analysis on the space scale, it was verified that an instrument with a compact size could be implemented and be quickly measured with a reasonable accuracy under microgravity conditions.

1. INTRODUCTION
 2. SPACE SCALE DESIGN AND IMPLEMENTATION
  2.1 Conceptual Measurement Scheme
  2.2 Space Scale Implementation
  2.3 Preliminary Test and Calibration of Space Scale
 3. GROUND & MICROGRAVITY EXPERIMENT
  3.1 Performance Test on Ground
  3.2 Performance Test under the Microgravity Condition
 4. CONCLUSION
 ACKNOWLEDGMENTS
 REFERENCES

• Youn-Kyu Kim(Convergence Technology Research Head Office, Korea Aerospace Research Institute, Daejeon 34133, Korea) Corresponding Author
• Joo-Hee Lee(Convergence Technology Research Head Office, Korea Aerospace Research Institute, Daejeon 34133, Korea)
• Gi-Hyuk Choi(Convergence Technology Research Head Office, Korea Aerospace Research Institute, Daejeon 34133, Korea)
• Ik-Hyeon Choi(Convergence Technology Research Head Office, Korea Aerospace Research Institute, Daejeon 34133, Korea)