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Jurnal Sains Dirgantara
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Articles 6 Documents
Search results for , issue "Vol 5, No.1 Desember (2007)" : 6 Documents clear
ANALISIS ORBIT SATELIT GSO Abd. Rachman; - Neflia
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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Abstract

Analysis 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 (76˚E dan 252.4˚E) 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 360˚. 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.
MODEL PELURUHAN DAN REENTRI ORBIT SATELIT LEO S.L. Manarung; Wlson Sinambela; Abd. Rachman
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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Abstract

Based to the non-central Earth's gravity causing the sekuler variation on the semi mayor axis and ecentricity of the LEO's satellite the software of orbital decay has been developed. The input for the software is the height, eccentricity existed in TLE (Two Line Elemen table), anapproximated ballistic coefficient and the atmospheric density on virous solar activity. The software has been used to predict the time is to 10%, and the error will become smaller if the software is executed closed to reentry time such a week before satellite reentry. The softaware can be used to approximate the ballistic coefficient of a satellite.
TELAH ORBIT SATELIT LAPAN-TUBSAT Nizam Ahmad; Thomas Djamaluddin
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (450.03 KB) | DOI: 10.30536/j.jsd.2007.v5.a659

Abstract

The study of orbit characteristics of LAPAN-TUBSAT can be done by using some microsatellites which identical in the case of mission and its orbit. This knowledge is usefull to reduce the failure of mission. This characteristics can be seen from the change of orbital elements caused by perturbation forces. LAPAN-TUBSAT is placed in Low Earth Orbit (LEO) at altitude about 630 km which has orbit near polar (i≈98˚). At this altitude, the perturbations come from non-gravitation force such as atmospheric drag and gravitation force from earth oblatness. From the simulation can be predicted that in the early years of its operation, the variation in altitude and semi major axis is relatively small. The means that this satellite could have the life time more than 50 years. The effect of earth oblatness will cause the regression of the nodes of about 1˚/day and the rotation of the line of apsides of about -3˚/day. These changes are not too critical for near polar orbit which means that satellite keeps conducted the mission goal such as satellite imaging.
PENGGUNAAN METODE ASPECT SENSITIVITY DALAM PENENTUAN TINGGI LAPISAN TROPOPAUSE DI SAAT MJO AKTIF MELINTAS KAWASAN KOTOTABANG DAN SEKITARNYA Eddy Hermawan; Irma Nurlela; Tri Wahyu Hadi
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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Abstract

This paper is mainly concerned to the utilization of aspect sensitivity (Pv/Po) method to define the tropopause height variation over the equatorial Indonesia, nearby Kototabang (0,2˚S; 100,32˚E), Bukittinggi, West Sumatera using the Equatorial Atmosphere Radar (EAR), especially during the Coupling Processes Equatorial Atmosphere (CPEA) Campign I in 2004 is already done. It is very important to be done since the tropopause is the buffer layer between troposphere and stratosphere (and also contrary) that usually called as the Stratosphere-Troposphere Exchanged (STE) (Holton, 1996). Validation's results with the radiosonde data shows that (Pv/Po relatively higher that radiosonde data. They are about 712 meter and 961 meter for Cold Point Tropopause (CPT) and Lapse Rate Tropopause (LRT) version, respectively. The mean difference between CPT and LRT itself is about 248 meter. This is enough valid considering to the maximum difference between of them not more 500 meter ( Haynes and Shepherd, 2001). This result then be applied in determining of tropopause height variation over Kototabang especially when the Madden-Julian Oscillation (MJO) passed over this region from November to December 2001. It shown that there are no significant differences between MJO active and no active on the tropopause height determination about 17.98 km and 17.73 km, respectively. The most interest is the tropopause height variation is larger during the MJO active than non active.To get the better understanding of tropopause height variation, especially with good time and spatial height resolution, the utilization of ERA and other instruments Kototabang are very needed.
HUBUNGAN AIR TERKANDUNG DENGAN REFLEKTIFITAS RADAR Eddy Hermawan; Yuanita Handayati
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (260.833 KB) | DOI: 10.30536/j.jsd.2007.v5.a660

Abstract

This paper is mainly concentrated to the correlation between Total Precipitable Water (TPW) on one single column of the vertical air mass and radar reflectivity (Z) over Kototabang (0.2˚S; 100.32˚E), Bukittinggi, West Sumatera based on to the analysis of Radio Acoustic Sounding System (RASS) and Boundary Layer Radar (BLR) data during the Coupling Processes of Equatorial Atmosphere (CPEA) Campaign I from April 10 to May 9, 2004 was going on. wWe firstly reviewed yhe basic concept of TPW using the Weisner method ti estimate the TPW value from the radiosonde data. We reviewed the basic concpt of RASS and BLR system also, especially on the Z data analysis. By arranging the mean value of RASS data every 10 minutes and 150 meter in height, respectively, we estimated the TPW values from the RASS data. By analysing the Cross Cirrelation Function (CCF) of both values taken from SPSS software version 13, we found a good agreement between TPW and Z parameter, especially on 5 May 2004. The correlation values are 0.05, and 0.61 at around 2.7 and 2.25 km, repectively. Although, the maximum correlation value in only 0.61, but this is still good enough to describe the correlation between TPW and Z.
KARAKTERISTIK ORBIT SATELIT MIKRO DI KETINGGIAN LEO Nizam Ahmad
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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Abstract

The 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.

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