Astra 4A (Sirius 4)

Anggota kelompok: 

Bernaldi Sugiarto 13608006

Afdhal 13608008

Robby Zieda Hilmi 13608034

Arie Eka Setiawan 13608050

Referensi:

http://www.satsig.net/sslist.htm
http://www.ses.com/4628572/astra-4a
http://www.satbeams.com/satellites?id=2149
http://www.ilslaunch.com/launch-services/baikonur-cosmodrome
http://www.khrunichev.ru/main.php?lang=en
http://en.wikipedia.org/wiki/Astra_4A
http://celestrak.com/norad/elements/geo.txt
http://www.astronautix.com/sites/baikonur.htm
http://space.skyrocket.de/doc_sdat/sirius-4.htm

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                                                      Satelit yang dipilih

Nama : Sirius 4 (Astra 4A)

Negara : Swedia

Tipe : Komunikasi

Operator : SES Sirius AB

Kontraktor : Lockheed Martin

Massa : 4385 kg

Orbit : GEO (Geostationary Earth Orbit)

Peluncur : Proton M/ Breeze M

 

Tempat Peluncuran

Nama : Baikonur Cosmodrome

Nama Lain : GIK-5 / NIIP-5; Tyuratam
Lokasi : Kazakhstan
Longitude : 63.3503 deg
Latitude : 45.9551 deg
Apogee : 92 km (57 mi)

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Skenario Alih Orbit (Menggunakan STK)

Skenario 1

  

Skenario 2

 

Skenario 3

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Delta V Total

Scenario 1
Segment	Variable	Value		Value for Change Plane		Delta V Total
Begin Hohmann	x	2.42723	km/sec			6.397146628		km/sec
Finish Hohmann	x	1.4	km/sec
Simple Plane Change	x	-0.96534	km/sec	2.5699166	km/sec
	y	-2.38172	km/sec
Scenario 2
Segment	Variable	Value		Value for Change Plane		Delta V Total
Begin Hohmann	x	2.42723	km/sec			4.698521666		km/sec
Combined Change	x	0.532283	km/sec	2.2712917	km/sec
	y	2.20804	km/sec
Scenario 3
Segment	Variable	Value		Value for Change Plane		Delta V Total
Change Plane	x	-2.23759	km/sec	6.0995111	km/sec	9.758371092		km/sec
	y	-5.67426	km/sec
Begin Hohmann	x	2.25886	km/sec
Finish Hohmann	x	1.4	km/sec

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Perhitungan ΔV total yang dibutuhkan 
(Hanya dilakukan untuk skenario 2 karena merupakan yang paling efektif)

-Orbit parkir (ketinggian 300km dari permukaan bumi dan inklinasi sebesar latitude lokasi peluncuran): 

µ=3.986 x 10⁵ km³/s² 
a1 = 6678.14 km 

Dengan persamaan vis viva integral:
   V=√(µ(2/r-1/a)) 
Didapat 
   V1=√(3.986 x 10⁵(1/6678.14)) 
   V1=7.725 km/s 

-Orbit transfer Hohmann

rp = 6678.14 km 
ra = 42165.4 km 


Didapatkan a transfer: 

   at = (rp+ra)/2 
   at = (6678.14+42165.4)/2 
   at = 24421.77 km


Kecepatan di pericenter: 
   Vp=√(3.986 x 10⁵(2/6678.14-1/24421.77))
   Vp=10.15 km/s 
Didapat:
   ΔV1 = Vp – V1 
   ΔV1 = 10.15 - 7.725
   ΔV1 = 2.427 km/s

Kecepatan di apocenter:
   Va=√(3.986 x 10⁵(2/42165.4-1/24421.77)) 
   Va=1.6078 km/s 

-Orbit akhir


a2 = 42165.4 km
  
Didapat: 
   V2=√(3.986 x 10⁵(1/42165.4)) 
   V2=3.07461 km/s 
Dengan penjumlahan vektor didapat: 
   ΔV2 = V2 – Va
   ΔV2 = 3.07461i – ((1.6078cos (45.9551))i+(1.6078sin(45.9551))j) 
   ΔV2 = 1.95683i – 1.15567j 
   ΔV2 = √(1.95683^2+(-1.15567)^2) 
   ΔV2 = 2.27 km/s

Sehingga ΔVtotal adalah 4.697 km/s

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Massa propelan yang dibutuhkan

Massa Satelit		4385	kg
Weight at Lift Off (including Payload)				691272	kg
Isp	300	s
g0	9.81	m/s2
Skenario 1
Delta V		Mf
6397.147	m/s	3886.171	kg
Skenario 2
Delta V		Mf
4698.522	m/s	3496.586	kg
Skenario 3
Delta V		Mf
9758.371	m/s	4225.801	kg

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Waktu yang dijalani satelit dari saat maneuver pertama (di orbit parkir) sampai dengan saat maneuver terakhir (untuk masuk ke orbit operasi)

T=0.5*P
T=π√((at)^3/µ)

T=π√((24421.77)^3/3.986 x 10⁵)
T=18990.96 s = 5.275 jam 

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