Satellite Launching to Space Launch Animation
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KNU Server: no sound but storable Launch Vehicles Launch Vehicles Not all are the same - Expendable and Reusable Sometimes they don’t work ! Two Types: Launch Vehicles
Expendable launchers are consumed during the launch process and fall into the sea or burn up in the atmosphere.
Reusable launchers make a soft landing on earth or at sea and can be refurbished for use on a future mission. Expendable Launchers
Many evolved from or were developed concurrently with military ICBM designs. Liquid fuel is most common for main engines. Additional solid rocket boosters may be strapped on for additional lifting capacity. Despite more than 50 years experience, launch failures are very common. Reusable Launchers
Designed specifically for spacecraft launch. Liquid fuel is used for main engines. Additional solid rocket boosters supply additional lifting capacity. Although not frequent, launch and recovery failures do happen. Challenger Columbia Launch Vehicle Classification
Heavy-Lift Light-Medium Lift Lifts up to 20 tons Lifts less than to LEO, up to 10,000 pounds to 10,000 pounds to LEO/MEO GTO, or 4,000 Cheaper than a pounds to GEO heavy-lift booster. Example: Russian Example: Pegasus Proton system air-launched system How do you launch to orbit?
LEO/MEO - direct orbital insertion is GEO common.
GTO GEO LEO 1st place in LEO 2nd kick into a GTO Apogee is at GEO Perigee is at LEO 3rd circularize orbit at GEO Some larger launchers can launch reduced mass payloads directly to GEO. Example of Clarke Satellite Belt Panamsat GEO Satellites Liquid Fuel Rocket
Nozzle Combustion Fuel Oxidizer Ve Chamber Thrust Exhaust
turbopumps
Liquid fuel and oxidizer, stored in tanks in the rocket is pumped into a combustion chamber where it burns. Hot exhaust gasses are expelled through a movable nozzle to provide thrust. Typical Fuels include hydrazine, kerosene, alcohol and liquid hydrogen, Oxidizer is typically liquid oxygen. XPIS - Xenon Ion Propulsion System
Boeing 601HP Thruster: Boeing 702 Thruster: 13 centimeters in diameter 25 centimeters in diameter 500 Watts 4500 Watts 18 mN of thrust 165 mN of thrust What makes the Rocket go ?
The Law of Conservation of Momentum is the key to understanding a rocket.
mv m dmv dv dmv
m = Mass of Rocket v = Velocity of Rocket dm' = Mass of Fuel Expelled v' = Velocity of Exhaust Rocket Equation 0 dmv mdv dmdv dmv v v ve
0 dmv mdv dmv ve
0 mdv dmve dm dm mdv dmve dv v e dm m m v v ln o Rocket Equation e m Boeing Delta Family Delta III had some problems
First Delta III launched suffered from a combustion chamber breach in the second stage engine. Stranded communications satellite in useless orbit. Shuttle mission may be used to attach a booster to the satellite and send it looping around the moon to return to GEO. Recently launched a dummy payload to prove its reliability. Delta III Launch
First stage falls away as viewed Solid booster separation from first from within the second stage engine stage. fairing. Delta IV Heavy Launcher
2-stage vehicle using common booster core and external solid rocket Graphite-Epoxy Motors (GEM’s). 4-5 m diameter launch fairing. Up to 28,950 to GTO. Stages are restartable in flight for more precise payload placement. RS-68 Main Engine
Boeing/Rocketdyne design. Liquid hydrogen fuel with LOX oxidizer. Produces 650,000 lbs thrust. Delta IV Mission Profile Lockheed Atlas V
• Lockheed’s answer to Boeing’s Delta series
•Heavy lift launcher – up to 19,114 lbs to GTO, 45,238 lbs to LEO. Lockheed Atlas V
•Successful first launch August 2002, placed the Hot Bird commercial communications satellite into GEO ( 13 degrees East) for Eutelsat. Lockheed Titan IV
Heavy-lift vehicle. Based on Titan ICBM, the Titan IV was first launched in 1989. Hybrid liquid- fuel/solid fuel first stage. 47,800 lb to LEO, 12,700 lb to GEO. Ariane
Ariane 1 first flew in December 1979 and was designed as a commercial launcher. Ariane 1 superseded as payload masses increased, currently Ariane 5 is the latest design. Payload capacity: GTO- 14,000 lb, LEO- 46,000 lb. Liquid fueled with solid 2 rocket boosters affixed to the first stage. Russian Proton
Heavy lift vehicle. Developed in the 1960’s, has been very reliable with over 260 missions completed (including one 9/5/00). 3 stages to LEO, 4 to GEO. 46,000 lb to LEO, 10,868 lb to GTO, 4,630 to GEO. Liquid fueled engines on all stages. Total liftoff weight of 1,500,000 lbs. Russian/Ukrainian Zenit
Medium-Heavy lift launcher. Used in Sea Launch system in addition to ground-based launches. Sea-Launch uses a converted oil drilling platform for launching from the equator. Equatorial launches get an energy boost from the Earth’s rotation and can place more payload into GEO. Sea Launch can place 11,550 to GEO. Chinese Long March
Different configurations depending on user requirements. Used to launch Iridium, other satellites. Up to 9,900 to GTO. Source of much political controversy in the US. $70 million launch cost. Boeing Inertial Upper Stage
2-stage booster used with the Space Shuttle and Titan IV launchers to boost satellites to GEO. Solid rocket motors 17.5 feet long, 9.5 feet dia. System weighs 32,000 lbs. Rotary Rocket Roton
Manned LEO launch and recovery capability. Fully reusable single stage to orbit vehicle. 7,000 lb per flight. $7,000,000 per flight ($1,000 per pound). Uses kerosene and oxygen. Soft landing via autorotation and thrusters. Several successful ground launches, now canceled. Rotary Rocket Roton Kistler K-1 Powered by Kuznetsov NK-33 and NK-43 engines left over from the defunct Soviet N-1 1970’s manned lunar rocket program. Up to 10,500 lb to LEO, depending on inclination. 2 stages, fully reusable, LOX/kerosene fueled. 841,000 lb GTOW. NASA contract awarded May 2001. Major problems for satellites
Positioning in orbit Stability Power Communications Harsh environment Positioning
This can be achieved by several methods One method is to use small rocket motors These use fuel - over half of the weight of most satellites is made up of fuel Often it is the fuel availability which determines the lifetime of a satellite Commercial life of a satellite typically 10-15 years Stability
It is vital that satellites are stabilised to ensure that solar panels are aligned properly to ensure that communications antennae are aligned properly Early satellites used spin stabilisation Either this required an inefficient omni- directional aerial Or antennae were precisely counter-rotated in order to provide stable communications Stability (2)
Modern satellites use reaction wheel stabilisation - a form of gyroscopic stabilisation Other methods of stabilisation are also possible including: eddy current stabilisation (forces act on the satellite as it moves through the earth’s magnetic field) Reaction wheel stabilisation
Heavy wheels which rotate at high speed - often in groups of 4. 3 are orthogonal, and the 4th (spare) is a backup at an angle to the others Driven by electric motors - as they speed up or slow down the satellite rotates If the speed of the wheels is inappropriate, rocket motors must be used to stabilise the satellite - which uses fuel Power
Modern satellites use a variety of power means Solar panels are now quite efficient, so solar power is used to generate electricity Batteries are needed as sometimes the satellites are behind the earth - this happens about half the time for a LEO satellite Nuclear power has been used - but not recommended Harsh Environment
Satellite components need to be specially “hardened” Circuits which work on the ground will fail very rapidly in space Temperature is also a problem - so satellites use electric heaters to keep circuits and other vital parts warmed up - they also need to control the temperature carefully Alignment
There are a number of components which need alignment Solar panels Antennae These have to point at different parts of the sky at different times, so the problem is not trivial Antenna alignment
A parabolic dish can be used which is pointing in the correct general direction Different feeder “horns” can be used to direct outgoing beams more precisely Similarly for incoming beams A modern satellite should be capable of at least 50 differently directed beams Inter-Satellite Links
It is also possible for satellites to communicate with other satellites Communication can be by microwave or by optical laser Communication Frequencies Frequency Band (GHz) Band Uplink Crosslink Downlink Bandwidth ======C 5.9-6.4 3.7 – 4.2 0.5 X 7.9-8.4 7.25-7.75 0.5 Ku 14-14.5 11.7-12.2 0.5 Ka 27-30 17-20 __ 30-31 20-21 __
Q ___ 40-41 1.0 41-43 2.0 V 50-51 ______1.0 (ISL) 54-58 3.9 59-64 5.0 Early satellite communications
Used C band in the range 3.7-4.2 GHz Could interfere with terrestrial communications Beamwidth is narrower with higher frequencies More recent communications
Greater use made of Ku band Use is now being made of Ka band Ku band assignments
© copyright 1996 MLE INC. Satellite management
Satellites do not just “stay” in their orbits They are pushed around by various forces They require active management Launch Animation
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