Jurnal Sains Dirgantara
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EVIDENCE OF ADDITIONAL LAYER FORMATION IN THE LOW LATITUDE IONOSPHERE
Get PDFIonogram recorded from four ionosonde stations are employed to study the accurrence of an additional layer at F-region altitudes during 1-15 March 1998. It was found that the appearance of the additional layer at the local noontime hours is a typical phenomenon at Parepare (4ËšS geographic, 14.8ËšS geomagnetic) and Manila (3.7ËšN geomagnetic), and was not observed at Chung-Li (14.2ËšN geomagnetic). Furthermore, the additional layer was nor seen from any indicate that the fountain effect plays an important role in the formation of the additional layer. However, they also suggest the dynamics of the layer formation are in some way influenced by the location of the station relative to the geographic aquator
KARAKTERISTIK ORBIT SATELIT MIKRO DI KETINGGIAN LEO
Get PDFThe Micro satellite is commonly placed in Low Earth Orbit (LEO) which has the altitude approximetely about 300-1000 km above surface of the earth. At this altitude, the the orbit of satellite will be influenced by perturbation force from atmospheric drag (Hasting, 1996) and earth oblateness. The understanding of orbit characteristics by studying the space environment where the satellite placed, will give much help in every launch of satellite. In this research, the study conducted by using 6 micro satellite as references with varying altitudes. The simulation result that the placement of satellite in the right position will reduce the effects of those perturbation on the satellite's orbit. It can be seen that all these micro satellites have conducted their mission goals, at least untill this time
ANALISIS ORBIT SATELIT GSO
Get PDFAnalysis of GSO satellite has done by using data from 57 satellite. It contains analysis on distortion of satellite's orbit due to perturbation forces and analysis on the station keeping maneuvers which have been done to keep the orbit on its ideal condition. Result of the analysis shows that it is not always a satellite located near the stable points (76ËšE dan 252.4ËšE) will oscillate about that longitudes. Ten among the post-operational satellite do oscillate about the stable points but the rest of them drift their longitudes from 0 to 360Ëš. The analysis also shows that orbital prediction using SDP4 model con only be accurate for prediction of inclination. Prediction of longitude, semimajor axis, and period based on TLE data are very sensitive to the related TLE
PEMANTAUAN BENDA JATUH ANTARIKSA DAN ANALISISNYA
Get PDFTelah dibuat sebuah prosedur pemantauan benda jatuh antariksa menggunakan sumber-sumber data dari internet dan perangkat-perangkat lunak orbit satelit. Teknik-teknik dalam prosedur ini telah digunakan sejak awal 2009 dan saat ini dapat disimpulkan bahwa prosedur tersebut efektif digunakan dengan asumsi akses ke sumber data tidak terganggu. Satu hal yang perlu diingat ketika memakai prosedur ini adalah prediksi waktu dan lokasi jatuh benda (reentry time and location) yang dipakainya tidak terbebas dari masalah akurasi. Hasil pemakaian prosedur menunjukkan bahwa sekalipun prediksi waktu jatuh yang dipakai menggunakan teknik special perturbation yang lebih akurat daripada SGP (Simplified General Perturbation), prediksi tersebut bisa memberikan hasil yang tidak valid jika dilakukan lebih awal dari 100 jam sebelum waktu jatuh. Kata kunci: Prosedur pemantauan, Benda jatuh antariksa, Special perturbation, Simplified general perturbation (SGP)
ANALISIS GERAK BINTIK MATAHARI BIPOLAR SEBELUM TERJADI FLARE PADA NOAA 0484 TANGGAL 21 DAN 22 OKTOBER 2003
Get PDFIn this reserach we analyzed the proper motion of individual sunspots whithin sunspots group NOAA 0484 in association with M2,4 and M1,7 flires occured on 21 October 2003 and 22 october 2003, respectively, using TRACE data (http://vestige.Imsal.com/TRACE). We measured the the movements of pairs of sunspots associated with flares relative to a reference spot in the active region whithin the period of 2 hours before the flare occurred and we calculated the mean velocities. We also measured the movements of other spots those were not associated with flares for comparisons. From these measurements and calculations, we found that (1) the distance between spots associated with flares are getting bigger especially in solar longitudinal direction and (2) they have bigger velocity that the other spots those were not associated to flares
DAMPAK VARIABILITAS IKLIM TERHADAP PRODUKSI PANGAN DI SUMATERA
Get PDFFood security will become unstable if extreme climate occurred frequently, such as dry and rainy season more than normal condition. This condition will have positive and negative effects, especially on agriculture sector. In this study, effect of climate variability on agriculture production over Sumatera Island for ten years (1991-2000) observation will be discussed. The result show that part of Sumatera Island has more surplus than deficit, so it has more planting season in one year. We suspect that El-Nino event has more effect than La-Nina event in decending crop agriculture productivity at Sumatera Island who has Monsoon raifall pattern
ANALISIS VARIABILITAS CURAH HUJAN DI SUMATERA BARAT DAN SELATAN DIKAITKAN GENGAN KEJADIAN DIPOLE MODE
Get PDFThe rainfall variability over the Western and Southern part of Sumatera Island related to te Dipole Mode (DM) event for period of twenty years (1980-1999) based on the monhly mean of rainfall, Dipole Mode Index (DMI), Sea Surface Temparature (SST), and Outgoing Longwave Radiation (OLR) data analysis have already investigated. By applying the spectral analysis technique Fast Fourier Transform (FFT), the most predominant peak ascillation of rainfall and DMI data has been identified. They are Semi Annual Oscillation (SAO) for Bukit Tinggi, Maninjau, and Sicincin sation, and Annual Oscillation (AO) for Padang-panjang, Padang, Batu Sangkar, Solok, Tabing, Bengkulu, Kotabumi, Jambi, and Palembang station, respectively. While the other predominant peak oscallation in period of 1.5 to 3 years are also found , especially on the DMI data analysis. It indicates that the rainfall variability over these areas could be related to the DM event, especially during DM (+) when the high pressure covers most of Indonesia region. When DM (+) occured, especially on JJA (June-July-August) and SON (September-October-November), the rainfall intensity over those area become less intil below normal condition. Conversely, when DM (-) occured, the amount of rainfall intensity is more than normal condition. Compared to DM (-), DM(+) looks more giving a significant influence to the rainfall in both areas
ANALISIS FRAKTAL EMISI SINYAL ULF DAN KAITANNYA DENGAN GEMPA BUMI DI INDONESIA
Get PDFAnomali sinyal ULF pada variasi medan geomagnet merupakan salah satu fenomena yang diyakini kebenarannya dalam studi elektromagnetik yang berhubungan dengan kejadian gempa bumi, seperti terjadinya emisi dari kerak bumi yang berasal dari sumber gempa. Dari studi terdahulu telah banyak ditemukan pertanda anomali sinyal ULF sebelum kejadian gempa bumi berskala besar. Untuk membuktikan kebenaran fenomena tersebut dan untuk menjelaskan hubungan antara fenomena elektromagnetik dan mekanisme fisis yang mungkin terkait, telah dilakukan analisis data geomagnet di Kototabang yang berhubungan dengan kejadian gempa Sumatera. Studi kasus dilakukan untuk mengamati anomali sinyal ULF yang berhubungan dengan gempa Aceh yang terjadi pada tanggal 26 Desember 2004 dan gempa Nias yang terjadi pada tanggal 28 Maret 2005 dengan menggunakan metode analisis fraktal. Dalam analisis fraktal, penentuan anomali emisi sinyal ULF dilakukan dengan menghitung dimensi fraktal dari deret waktu ULF. Untuk menentukan dimensi fraktal digunakan metode Jurnal Sains Dirgantara Vol. 6 No. 1 Desember 2008:39-46 40 Higuchi karena dimensi fraktal yang dihitung dengan metode ini lebih stabil dibandingkan dengan metode lainnya. Hasil yang diperoleh menunjukkan terjadinya penurunan dimensi fraktal 1 bulan hingga beberapa minggu sebelum kejadian gempa besar tersebut. Hal ini merupakan indikasi dari fase awal terjadinya peningkatan aktivitas seismik yang kemungkinan terkait dengan variasi geomagnet yang diakibatkan oleh aktivitas lokal yang berasal dari litosfer yang dipicu oleh kejadian gempa bumi di Aceh dan Nias. Kata kunci : Anomali sinyal ULF, Dimensi fraktal, Aktivitas seismi