Download - lect satt 2.ppt
Satellite pictures
October 1957, the first artificial satellite Sputnik -I was launched by former Soviet Russia.
The first artificial passive satellite Echo-I of NASA was launched in August 1960.
In July 1962 active satellite Telstar was developed and launched
• Space Segment includes:
– Satellite (transponders etc)
– Means for launching satellite
– Electrical Power System
– Mechanical structure
– Communication Antennas
– Attitude and orbit control
system
At the Equator
equator
11 day travel, 3 days on site, 9 days back1. and 2. stage fueled on launch site; 3. stage and satellite fueled in Long Beach
The Launch Service Alliance
ArianeSpace, Boeing Launch Services, and Mitsubishi Heavy Industries
↪ mutual backup to mitigate schedule risks, range issues, etc.
Launching cntd…
The launch process can be divided into two phases:
• The Launch Phase
- Satellite placed into the transfer orbit.
• The Orbit Injection Phase
- Satellite transferred from elliptical transfer orbit to
geosynchronous orbit.
Launch Vehicle
• Function-Place the satellite into the desired Orbit.
• Two types
Expandable
• Launch vehicles can be used only once.
• Most of the satellite are of this type.
Reusable
• Only one reusable launch vehicle available.
Satellite ejected from the cargo compartment.
• The Space Shuttle performs the functions of the first two stages of an expendable launch vehicle.
• The satellite and third stage assembly are ejected after reaching elevation of 150 to 200 miles.
Launching contd….• By riding on a rocket or in the cargo bay of the Space Shuttle.
• At about 120 miles (193 km) up, the rocket's navigational system fires small rockets, just enough to turn the launch vehicle into a horizontal position.
• Inertial guidance system mechanism is used to calculate adjustments to tilt the rocket
Satellite Power SystemsSatellite Power Systems• Main source of power is solar cell panels - new solar cells
are increasingly efficient
• The solar cell system is backed up by battery system that provides energy during solar eclipses and other periods of outages.
• Typical power levels of 2 to 5 KWs for Fixed Satellite Systems and 10 to 12 KWs for Mobile and Broadcast Satellite Systems.
Batteries• latest battery technology is represented by Lithium Ion
systems that can provide a greater power density for longer periods of time and survive a greater depth of discharge
• Satellite Control Centre function:
– Tracking of the satellite
– Receiving data
– Eclipse management of satellite
• The ground segment consists of
– Earth Stations
– User terminals and interfaces
– Network control centre
– Transmit equipment.
– Receive equipment.
– Antenna system.
Satellite Communications System
Uplink Down Link
Transmit Earth Station Receive Earth Station
IDU IDURFT RFT
RF
ConceptTransponder
Earth station (site A) Earth station(site B)
IRRADIUM
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