In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.

1. INTRODUCTION
 2. INSTRUMENTATION
 3. RESULTS
 4. DISCUSSION AND SUMMARY
 ACKNOWLEDGEMENTS
 REFERENCES

• Junhyun Lee(School of Space Research, Kyung Hee University)
• Ensang Lee(School of Space Research, Kyung Hee University, Institute of Natural Sciences, Kyung Hee University) Corresponding Author
• Jaejin Lee(Korea Astronomy and Space Science Institute)
• Khan-Hyuk Kim(School of Space Research, Kyung Hee University)
• Jongho Seon(School of Space Research, Kyung Hee University)
• Dong-Hun Lee(School of Space Research, Kyung Hee University)
• Ho Jin(School of Space Research, Kyung Hee University)
• Eung-Hyun Kim(Korea Aerospace Research Institute)
• Hyun-Jin Jeon(Korea Aerospace Research Institute)
• Seong-Bin Lim(Korea Aerospace Research Institute)
• Taeyoun Kim(Korea Aerospace Research Institute)
• Jaewoong Jang(Korea Aerospace Research Institute)
• Kyung-Duk Jang(Korea Aerospace Research Institute)
• Kwangsun Ryu(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology)