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Studies on atmospheric density were very important to obtain a correction factor for the atmospheric density model. Thus, improvement of atmospheric models accuracy, i.e. CIRA, JASCHIA, NRLMSISE, became important in its application for re-entry prediction, satellite tracking and mitigation of the collisions probability between active satellites with space debris. GPS equipment installed in LAPAN-A2 indirectly measured the upper atmospheric density variation in-situ from the satellite orbit path. Notwithstanding the measurement had a lower temporal resolution than using accelerometer, but still gives better resolution than using Two-Line Element (TLE) data. This study had successfully determined upper atmospheric density variation with a 10 second resolution using LAPAN-A2 GPS data. The LAPAN-A2 GPS data validated using In-track Radial Cross-track (RIC) had ± 2 km error compared to the TLE data. It was also found that there was influence of solar activity on atmospheric density changes obtained from the LAPAN-A2 GPS data. Abstrak Studi kerapatan atmosfer atas sangat penting untuk memperoleh faktor koreksi dari suatu model kerapatan atmosfer. Peningkatan akurasi dari model atmosfer yang telah ada (CIRA, JASCHIA, NRLMSISE) sangat penting dalam penerapannya untuk prediksi re-entry , penjejakan satelit dan prakiraan kemungkinan terjadinya tabrakan antara satelit aktif dengan sampah antariksa. Peralatan GPS yang terpasang di satelit LAPAN-A2 secara tidak langsung dapat melakukan pengukuran in-situ perubahan kerapatan atmosfer atas dari orbit yang dilaluinya, meskipun tingkat resolusi temporalnya masih lebih rendah dibandingkan menggunakan instrumen akselerometer tetapi masih jauh lebih baik dibandingkan menggunakan data Two-Line Element (TLE). Studi ini telah berhasil memperoleh variasi kerapatan atmosfer atas dengan resolusi 10 detik menggunakan data posisi GPS LAPAN-A2. Selain itu, diperoleh pula tingkat kesalahan dalam koordinat satelit ( Radial Intrack Crosstrack - RIC) data TLE terhadap data posisi GPS LAPAN-A2 sebesar ± 2 km. Selain itu terlihat pula pengaruh aktivitas matahari terhadap perubahan kerapatan atmosfer atas yang diperoleh dari data posisi GPS LAPAN-A2

jurnal sains kedirganantaraan/jurnal sains kedirganantaraan

PENGARUH AKTIVITAS MATAHARI TERHADAP KERAPATAN ATMOSFER ATAS BERDASARKAN DATA POSISI GPS SATELIT LAPAN-A2 (SOLAR ACTVITY INFLUENCE ON THE UPPER ATMOSPHERIC DENSITY DERIVED FROM GPS DATA ON LAPAN-A2 SATELLITE)