Sunday, November 8, 2009

Description of Space Shuttle

The Space Shuttle is the first orbital spacecraft designed for reusability. It carries payloads to low Earth orbit, provides crew rotation for the International Space Station (ISS), and performs servicing missions. The orbiter can also recover satellites and other payloads from orbit and return them to Earth. Each Shuttle was designed for a projected lifespan of 100 launches or 10 years' operational life, although this was later extended. The person in charge of designing the STS was Maxime Faget, who had also overseen the Mercury, Gemini and Apollo spacecraft designs. The crucial factor in the size and shape of the Shuttle Orbiter was the requirement that it be able to accommodate the largest planned commercial and classified satellites, and have the cross-range recovery range to meet the requirement for classified USAF missions for a once-around abort from a launch to a polar orbit. Factors involved in opting for solid rockets and an expendable fuel tank included the desire of the Pentagon to obtain a high-capacity payload vehicle for satellite deployment, and the desire of the Nixon administration to reduce the costs of space exploration by developing a spacecraft with reusable components

Six airworthy Space Shuttle orbiters have been built; the first, Enterprise, was not built for orbital space flight, and was used only for testing purposes. Five space-worthy orbiters were built: Columbia, Challenger, Discovery, Atlantis, and Endeavour. Enterprise was originally intended to be made fully space-worthy after use for the approach and landing test (ALT) program, but it was found more economical to upgrade the structural test article STA-099 into orbiter Challenger (OV-099). Challenger disintegrated 73 seconds after launch in 1986, and Endeavour was built as a replacement from structural spare components. Columbia broke apart during re-entry in 2003.

Each Space Shuttle is a reusable launch system that is composed of three main assemblies: the reusable Orbiter Vehicle (OV), the external tank (ET), and the two reusable solid rocket boosters (SRBs). The tank and boosters are jettisoned during ascent; only the orbiter enters orbit. The vehicle is launched vertically like a conventional rocket, and the orbiter glides to a horizontal landing, after which it is refurbished for reuse. The SRBs parachute back to earth, where they are collected from the ocean and refilled for another use. Although the external tanks have always been discarded, it is possible to take them into orbit and re-use them (such as for incorporation into a space station).

Roger A. Pielke, Jr. has estimated that the Space Shuttle program has cost about US$170 billion (2008 dollars) through early 2008. This works out to an average cost per flight of about US$1.5 billion. However, two missions were paid for by Germany, Spacelab D-1 and D-2 (for Deutschland) with a mission control in Oberpfaffenhofen, Germany.

At times, the orbiter itself is referred to as the space shuttle. Technically, this is a slight misnomer, as the actual "Space Transportation System" (space shuttle) is the combination of the orbiter, the external tank, and the two solid rocket boosters. Combined, these are referred to as the "Stack"; the components are assembled in the Vehicle Assembly Building, which was originally built to assemble the Apollo Saturn V rocket stacks.

Orbiter vehicle

The orbiter resembles a conventional aircraft, with double-delta wings swept 81° at the inner leading edge and 45° at the outer leading edge. Its vertical stabilizer's leading edge is swept back at a 50° angle. The four elevons, mounted at the trailing edge of the wings, and the rudder/speed brake, attached at the trailing edge of the stabilizer, with the body flap, control the orbiter during descent and landing.

The orbiter has a large payload bay measuring 15 by 60 feet (4.6 by 18 m) comprising most of the fuselage. Two mostly symmetrical lengthwise payload bay doors hinged on either side of the bay comprise its entire top. Payloads are generally loaded horizontally into the bay while the orbiter is oriented vertically on the launch pad and unloaded vertically in the near-weightless orbital environment by the orbiter's robotic remote manipulator arm (under astronaut control), EVA astronauts, or under the payloads' own power (as for satellites attached to a rocket "upper stage" for deployment.)

Three Space Shuttle main engines (SSMEs) are mounted on the orbiter's aft fuselage in a triangular pattern. The three engines can swivel 10.5 degrees up and down, and 8.5 degrees from side to side during ascent to change the direction of their thrust and steer the shuttle as well as push. The orbiter structure is made primarily from aluminum alloy, although the engine thrust structure is made primarily from titanium alloy.

The orbiter can be used in conjunction with a variety of add-ons depending on the mission. This has included orbital laboratories (Spacelab, Spacehab), boosters for launching payloads farther into space (Inertial Upper Stage, Payload Assist Module), and other add-ons like the Extended Duration Orbiter, Multi-Purpose Logistics Modules, and Canadarm (RMS).

The space-capable orbiters built are OV-099 Challenger, OV-102 Columbia, OV-103 Discovery, OV-104 Atlantis, and OV-105 Endeavour.[10]

Orbiter add-ons:

Solid Rocket Boosters

Two solid rocket boosters (SRBs) each provide 12.5 million newtons (2.8 million lbf) of thrust at liftoff, which is 83% of the total thrust needed for liftoff. The SRBs are jettisoned two minutes after launch at a height of about 45.7 kilometers (150,000 ft), and then deploy parachutes and land in the ocean to be recovered. The SRB cases are made of steel about 1.3 centimeters (0.51 in) thick The Solid Rocket Boosters are re-used many times; the casing used in Ares I engine testing in 2009 consisted of motor cases that have been flown, collectively, on 48 shuttle missions, including STS-1.[14]

Flight systems

Early shuttle missions took along the GRiD Compass, arguably one of the first laptop computers. The Compass sold poorly, as it cost at least US$8000, but it offered unmatched performance for its weight and size. NASA was one of its main customers.

The shuttle was one of the earliest craft to use a computerized fly-by-wire digital flight control system. This means no mechanical or hydraulic linkages connect the pilot's control stick to the control surfaces or reaction control system thrusters.

A primary concern with digital fly-by-wire systems is reliability. Much research went into the shuttle computer system. The shuttle uses five identical redundant IBM 32-bit general purpose computers (GPCs), model AP-101, constituting a type of embedded system. Four computers run specialized software called the Primary Avionics Software System (PASS). A fifth backup computer runs separate software called the Backup Flight System (BFS). Collectively they are called the Data Processing System (DPS)

The design goal of the shuttle's DPS is fail-operational/fail-safe reliability. After a single failure, the shuttle can still continue the mission. After two failures, it can still land safely.

The four general-purpose computers operate essentially in lockstep, checking each other. If one computer fails, the three functioning computers "vote" it out of the system. This isolates it from vehicle control. If a second computer of the three remaining fails, the two functioning computers vote it out. In the rare case of two out of four computers simultaneously failing (a two-two split), one group is picked at random.

Atlantis deploys landing gear before landing on a selected runway just like a common aircraft.

The Backup Flight System (BFS) is separately developed software running on the fifth computer, used only if the entire four-computer primary system fails. The BFS was created because although the four primary computers are hardware redundant, they all run the same software, so a generic software problem could crash all of them. Embedded system avionic software is developed under totally different conditions from public commercial software: the number of code lines is tiny compared to a public commercial software, changes are only made infrequently and with extensive testing, and many programming and test personnel work on the small amount of computer code. However, in theory it can still fail, and the BFS exists for that contingency. While BFS will run in parallel with PASS, to date, BFS has never been engaged to take over control from PASS during any shuttle mission.

The software for the shuttle computers is written in a high-level language called HAL/S, somewhat similar to PL/I. It is specifically designed for a real time embedded system environment.

The IBM AP-101 computers originally had about 424 kilobytes of magnetic core memory each. The CPU could process about 400,000 instructions per second. They have no hard disk drive, and load software from magnetic tape cartridges.

In 1990, the original computers were replaced with an upgraded model AP-101S, which has about 2.5 times the memory capacity (about 1 megabyte) and three times the processor speed (about 1.2 million instructions per second). The memory was changed from magnetic core to semiconductor with battery backup.

Space Shuttle program insignia

Markings and insignia

The typeface used on the Space Shuttle Orbiter is Helvetica.[19] On the side of the shuttle between the cockpit windows and the cargo bay doors is the name of the orbiter. Underneath the rear of the cargo bay doors is the NASA insignia, the text 'United States' and a flag of the United States. Another United States flag appears on the right wing.


During STS-101, Atlantis was the first shuttle to fly with a glass cockpit.

Internally, the shuttle remains largely similar to the original design, with the exception of the improved avionics computers. In addition to the computer upgrades, the original analog primary flight instruments were replaced with modern full-color, flat-panel display screens, similar to those of contemporary airliners like the Airbus A380 and Boeing 777. This is called a glass cockpit. Programmable calculators are carried as well (originally the HP-41C). With the coming of the ISS, the orbiter's internal airlocks have been replaced with external docking systems to allow for a greater amount of cargo to be stored on the shuttle's mid-deck during station resupply missions.

The Space Shuttle Main Engines (SSMEs) have had several improvements to enhance reliability and power. This explains phrases such as "Main engines throttling up to 104%." This does not mean the engines are being run over a safe limit. The 100% figure is the original specified power level. During the lengthy development program, Rocketdyne determined the engine was capable of safe reliable operation at 104% of the originally specified thrust. They could have rescaled the output number, saying in essence 104% is now 100%. To clarify this would have required revising much previous documentation and software, so the 104% number was retained. SSME upgrades are denoted as "block numbers", such as block I, block II, and block IIA. The upgrades have improved engine reliability, maintainability and performance. The 109% thrust level was finally reached in flight hardware with the Block II engines in 2001. The normal maximum throttle is 104%, with 106% or 109% used for mission aborts.

For the first two missions, STS-1 and STS-2, the external tank was painted white to protect the insulation that covers much of the tank, but improvements and testing showed that it was not required. The weight saved by not painting the tank results in an increase in payload capability to orbit. Additional weight was saved by removing some of the internal "stringers" in the hydrogen tank that proved unnecessary. The resulting "light-weight external tank" has been used on the vast majority of shuttle missions. STS-91 saw the first flight of the "super light-weight external tank". This version of the tank is made of the 2195 aluminum-lithium alloy. It weighs 3.4 tonnes (7,500 lb) less than the last run of lightweight tanks. As the shuttle cannot fly unmanned, each of these improvements has been "tested" on operational flights.

The SRBs (Solid Rocket Boosters) have undergone improvements as well. Design engineers added a third O-ring seal to the joints between the segments after the Space Shuttle Challenger disaster.

The three nozzles of the Main Engine cluster with the two Orbital Maneuvering System (OMS) pods, and the vertical stabilizer above.

Several other SRB improvements were planned in order to improve performance and safety, but never came to be. These culminated in the considerably simpler, lower cost, probably safer and better performing Advanced Solid Rocket Booster. These rockets entered production in the early to mid-1990s to support the Space Station, but were later canceled to save money after the expenditure of $2.2 billion.[21] The loss of the ASRB program resulted in the development of the Super LightWeight external Tank (SLWT), which provides some of the increased payload capability, while not providing any of the safety improvements. In addition, the Air Force developed their own much lighter single-piece SRB design using a filament-wound system, but this too was canceled.

STS-70 was delayed in 1995, when woodpeckers bored holes in the foam insulation of Discovery's external tank. Since then, NASA has installed commercial plastic owl decoys and inflatable owl balloons which must be removed prior to launch.[22] The delicate nature of the foam insulation has been the cause of damage to the Thermal Protection System, the tile heat shield and heat wrap of the orbiter, during recent launches. NASA remains confident that this damage, while it was the primary cause of the Space Shuttle Columbia disaster on February 1, 2003, will not jeopardize the objective of NASA to complete the International Space Station (ISS) in the projected time allotted.

A cargo-only, unmanned variant of the shuttle has been variously proposed, and rejected since the 1980s. It was called the Shuttle-C, and would have traded re-usability for cargo capability, with large potential savings from reusing technology developed for the space shuttle.

On the first four shuttle missions, astronauts wore modified U.S. Air Force high-altitude full-pressure suits, which included a full-pressure helmet during ascent and descent. From the fifth flight, STS-5, until the loss of Challenger, one-piece light blue nomex flight suits and partial-pressure helmets were worn. A less-bulky, partial-pressure version of the high-altitude pressure suits with a helmet was reinstated when shuttle flights resumed in 1988. The Launch-Entry Suit ended its service life in late 1995, and was replaced by the full-pressure Advanced Crew Escape Suit (ACES), which resembles the Gemini space suit worn in the mid-1960s.

To extend the duration that orbiters can stay docked at the ISS, the Station-to-Shuttle Power Transfer System (SSPTS) was installed. The SSPTS allows these orbiters to use power provided by the ISS to preserve their consumables. The SSPTS was first used successfully on STS-118.

Technical data

Space Shuttle Atlantis transported by a Boeing 747Shuttle Carrier Aircraft (SCA), 1998 (NASA).

Space Shuttle Endeavour being transported by a Boeing 747.

Space Shuttle Orbiter and Soyuz-TM (drawn to scale).

An overhead view of Atlantis as it sits atop the Mobile Launcher Platform (MLP) before STS-79. Two Tail Service Masts (TSMs) to either side of the orbiter's tail provide umbilical connections for propellant loading and electrical power.

Water is released onto the mobile launcher platform on Launch Pad 39A at the start of a rare sound suppression system test in 2004. During launch, 300,000 US gallons (1,100 m³) are poured onto the pad in only 41 seconds.

Two space shuttles sit at launch pads. This particular occasion is due to the final Hubble servicing mission, where the International Space Station is unreachable, necessitating having a shuttle on standby for a possible rescue mission.

Orbiter specifications (for Endeavour, OV-105)

  • Length: 122.17 ft (37.237 m)
  • Wingspan: 78.06 ft (23.79 m)
  • Height: 58.58 ft (17.86 m)
  • Empty weight: 172,000 lb (78,000 kg)[24]
  • Gross liftoff weight: 240,000 lb (110,000 kg)
  • Maximum landing weight: 230,000 lb (100,000 kg)
  • Main engines: Three Rocketdyne Block IIA SSMEs, each with a sea level thrust of 393,800 lbf (1.752 MN) at 104% power
  • Maximum payload: 55,250 lb (25,060 kg)
  • Payload bay dimensions: 15 by 59 ft (4.6 by 18 m)
  • Operational altitude: 100 to 520 nmi (190 to 960 km; 120 to 600 mi)
  • Speed: 7,743 m/s (27,870 km/h; 17,320 mph)
  • Crossrange: 1,085 nmi (2,009 km; 1,249 mi)
  • Crew: Varies. The earliest shuttle flights had the minimum crew of two; many later missions a crew of five. Today, typically seven people fly (commander, pilot, several mission specialists, and rarely a flight engineer). On two occasions, eight astronauts have flown (STS-61-A, STS-71). Eleven people could be accommodated in an emergency mission (see STS-3xx).

External tank specifications (for SLWT)

  • Length: 46.9 m (154 ft)
  • Diameter: 8.4 m (28 ft)
  • Propellant volume: 2,025 m3 (534,900 US gal)
  • Empty weight: 26,535 kg (58,500 lb)
  • Gross liftoff weight: 756,000 kg (1,670,000 lb)

Solid Rocket Booster specifications

  • Length: 45.46 m (149 ft)
  • Diameter: 3.71 m (12.2 ft
  • Empty weight (per booster): 68,000 kg (150,000 lb)
  • Gross liftoff weight (per booster): 571,000 kg (1,260,000 lb)
  • Thrust (at liftoff, sea level): 12.5 MN (2,800,000 lbf)[11]

System Stack specifications

  • Height: 56 m (180 ft)
  • Gross liftoff weight: 2,000,000 kg (4,400,000 lb)
  • Total liftoff thrust: 30.16 MN (6,780,000 lbf)

Mission profile


All Space Shuttle missions are launched from Kennedy Space Center (KSC). The same weather criteria used for launch are also for end of mission landing at KSC, and include precipitation (none allowed at the launch pad or flight path), temperatures above 99 °F (37.2 °C) or below 35 °F (1.7 °C), a 20% or greater chance of lightning within 5 nautical miles and cloud cover allows direct visual observation of the shuttle through 8,000 feet.[27] The shuttle will not be launched under conditions where it could be struck by lightning. Aircraft are often struck by lightning with no adverse effects because the electricity of the strike is dissipated through its conductive structure and the aircraft is not electrically grounded. Like most jet airliners, the shuttle is mainly constructed of conductive aluminum, which would normally shield and protect the internal systems. However, upon takeoff the shuttle sends out a long exhaust plume as it ascends, and this plume can trigger lightning by providing a current path to ground. The NASA Anvil Rule for a shuttle launch states that an anvil cloud cannot appear within a distance of 10 nautical miles.[28] The Shuttle Launch Weather Officer will monitor conditions until the final decision to scrub a launch is announced. In addition, the weather conditions must be acceptable at one of the Transatlantic Abort Landing sites (one of several Space Shuttle abort modes) to launch as well as the solid rocket booster recovery area.[27][29] While the shuttle might safely endure a lightning strike, a similar strike caused problems on Apollo 12, so for safety NASA chooses not to launch the shuttle if lightning is possible (NPR8715.5).

STS mission profile

Historically, the Shuttle was not launched if its flight would run from December to January (a year-end rollover or YERO). Its flight software, designed in the 1970s, was not designed for this, and would require the orbiter's computers be reset through a change of year, which could cause a glitch while in orbit. In 2007, NASA engineers devised a solution so Shuttle flights could cross the year-end boundary.

On the day of a launch, after the final hold in the countdown at T minus 9 minutes, the Shuttle goes through its final preparations for launch, and the countdown is automatically controlled by the Ground Launch Sequencer (GLS), software at the Launch Control Center, which stops the count if it senses a critical problem with any of the Shuttle's on-board systems. The GLS hands off the count to the Shuttle's on-board computers at T minus 31 seconds, in a process called auto sequence start.

At T minus 16 seconds, the massive sound suppression system (SPS) begins to drench the Mobile Launcher Platform (MLP) and SRB trenches with 300,000 US gallons (1,100 m3) of water to protect the Orbiter from damage by acoustical energy and rocket exhaust reflected from the flame trench and MLP during liftoff.

At T-minus 10 seconds, hydrogen igniters are activated under each engine bell to quell the stagnant gas inside the cones before ignition. Failure to burn these gases can trip the onboard sensors and create the possibility of an overpressure and explosion of the vehicle during the firing phase. The main engine turbopumps also begin charging the combustion chambers with liquid hydrogen and liquid oxygen at this time. The computers reciprocate this action by allowing the redundant computer systems to begin the firing phase.

Shuttle launch of Atlantis at sunset in 2001. The sun is behind the camera, and the plume's shadow intersects the moon across the sky.

The three Space Shuttle Main Engines (SSMEs) start at T minus 6.6 seconds. The main engines ignite sequentially via the shuttle's general purpose computers (GPCs) at 120 millisecond intervals. The GPCs require that the engines reach 90% of their rated performance to complete the final gimbal of the main engine nozzles to liftoff configuration. When the SSMEs start, the water from the sound suppression system flashes into a large volume of steam that shoots southward. All three SSMEs must reach the required 100% thrust within three seconds, otherwise the onboard computers will initiate an RSLS abort. If the onboard computers verify normal thrust buildup, at T minus 0 seconds, the SRBs are ignited. At this point the vehicle is committed to takeoff, as the SRBs cannot be turned off once ignited. After the SRBs reach a stable thrust ratio, pyrotechnic nuts are detonated by radio controlled signals from the shuttle's GPC's to release the vehicle The plume from the solid rockets exits the flame trench in a northward direction at near the speed of sound, often causing a rippling of shockwaves along the actual flame and smoke contrails. At ignition, the GPC's mandate the firing sequences via the Master Events Controller, a computer program integrated with the shuttle's four redundant computer systems. There are extensive emergency procedures (abort modes) to handle various failure scenarios during ascent. Many of these concern SSME failures, since that is the most complex and highly stressed component. After the Challenger disaster, there were extensive upgrades to the abort modes.

After the main engines start, but while the solid rocket boosters are still clamped to the pad, the offset thrust from the Shuttle's three main engines causes the entire launch stack (boosters, tank and shuttle) to pitch down about 2 m at cockpit level. This motion is called the "nod", or "twang" in NASA jargon. As the boosters flex back into their original shape, the launch stack pitches slowly back upright. This takes approximately six seconds. At the point when it is perfectly vertical, the boosters ignite and the launch commences.

Shortly after clearing the tower the Shuttle begins a roll and pitch program to set its orbital inclination and so that the vehicle is below the external tank and SRBs, with wings level. The vehicle climbs in a progressively flattening arc, accelerating as the weight of the SRBs and main tank decrease. To achieve low orbit requires much more horizontal than vertical acceleration. This is not visually obvious, since the vehicle rises vertically and is out of sight for most of the horizontal acceleration. The near circular orbital velocity at the 380 kilometers (236 mi) altitude of the International Space Station is 7.68 kilometers per second 27,650 km/h (17,180 mph), roughly equivalent to Mach 23 at sea level. As the International Space Station orbits at an inclination of 51.6 degrees, the Shuttle has to set its inclination to the same value to rendezvous with the station.

SSLV at Mach 2.46 and 66,000 ft (20,000 m). The surface of the vehicle is colored by the pressure coefficient, and the gray contours represent the density of the surrounding air, as calculated using the overflow codes.

Around a point called Max Q, where the aerodynamic forces are at their maximum, the main engines are temporarily throttled back to avoid overspeeding and hence overstressing the Shuttle, particularly in vulnerable areas such as the wings. At this point, a phenomenon known as the Prandtl-Glauert singularity occurs, where condensation clouds form during the vehicle's transition to supersonic speed.

126 seconds after launch, explosive bolts release the SRBs and small separation rockets push them laterally away from the vehicle. The SRBs parachute back to the ocean to be reused. The Shuttle then begins accelerating to orbit on the Space Shuttle main engines. The vehicle at that point in the flight has a thrust-to-weight ratio of less than one – the main engines actually have insufficient thrust to exceed the force of gravity, and the vertical speed given to it by the SRBs temporarily decreases. However, as the burn continues, the weight of the propellant decreases and the thrust-to-weight ratio exceeds 1 again and the ever-lighter vehicle then continues to accelerate toward orbit.

A picture taken of the afterglow from STS 119 with colors varying from white to orange.

The vehicle continues to climb and takes on a somewhat nose-up angle to the horizon – it uses the main engines to gain and then maintain altitude while it accelerates horizontally towards orbit. At about five and three-quarter minutes into ascent, the orbiter rolls heads up to switch communication links from ground stations to Tracking and Data Relay Satellites.

Finally, in the last tens of seconds of the main engine burn, the mass of the vehicle is low enough that the engines must be throttled back to limit vehicle acceleration to 3 g (30 m/s²), largely for astronaut comfort.

The main engines are shut down before complete depletion of propellant, as running dry would destroy the engines. The oxygen supply is terminated before the hydrogen supply, as the SSMEs react unfavorably to other shutdown modes. (Liquid oxygen has a tendency to react violently, and supports combustion when it encounters hot engine metal.) The external tank is released by firing explosive bolts and falls, largely burning up in the atmosphere, though some fragments fall into the ocean, in either the Indian Ocean or the Pacific Ocean depending on launch profile. The sealing action of the tank plumbing and lack of pressure relief systems on the external tank helps it break up in the lower atmosphere. After the foam burns away during reentry, the heat causes a pressure buildup in the remaining liquid oxygen and hydrogen until the tank explodes. This ensures that any pieces that fall back to Earth are small.

To prevent the shuttle from following the external tank back into the lower atmosphere, the Orbital maneuvering system (OMS) engines are fired to raise the perigee higher into the upper atmosphere. On some missions (e.g., missions to the ISS), the OMS engines are also used while the main engines are still firing. The reason for putting the orbiter on a path that brings it back to Earth is not just for external tank disposal but also one of safety: if the OMS malfunctions, or the cargo bay doors cannot open for some reason, the shuttle is already on a path to return to earth for an emergency abort landing.

Space Shuttle

Space Shuttle Discovery launches at the start of STS-120.

The Space Shuttle, part of the Space Transportation System (STS), is a spacecraft operated by NASA for orbital human spaceflight missions. It began operations in the 1980s and is scheduled to be retired from service in 2010 after 134 launches. Major missions have included launching numerous satellites and interplanetary probes, conducting space science experiments, and servicing and construction of space stations. STS has been used for orbital space missions by NASA, the U.S. Department of Defense, the European Space Agency, and Germany. The United States funded STS development and shuttle operations.

At launch, Space Shuttle consists of a dark orange-colored external tank (ET);[1][2] two white, slender Solid Rocket Boosters (SRBs); and the STS Orbiter Vehicle (OV) which contains the crew and payload. Payloads can be launched into higher orbits with either of two different booster stages developed for STS (1 stage PAM or 2 stage IUS).

The shuttle stack launches vertically like a conventional rocket from a mobile launch platform. It lifts off under the power of its two solid rocket boosters (SRBs) and its three main engines (SSMEs), the latter fueled by liquid hydrogen and liquid oxygen from the external tank. The space shuttle has a two stage ascent. The boosters are used only for the first stage, while the main engines burn for both stages. About two minutes after liftoff, staging occurs: the SRBs are released, and shortly begin falling into the ocean to be retrieved for reuse. The shuttle orbiter and external tank continue to ascend under power from the three main engines and their inertia. Upon reaching orbit, the main engines are shut down, and the external tank is jettisoned downward and falls to burn up in the atmosphere. However, it is possible for it be re-used in orbit for various applications.[3] At this point, the orbital maneuvering system (OMS) engines may be used to adjust or circularize the achieved orbit.

The orbiter carries astronauts and payload such as satellites or space station parts into low earth orbit, into the Earth's upper atmosphere or thermosphere.[4] Usually, five to seven crew members ride in the orbiter. Two crew members, the Commander and Pilot, are sufficient for a minimal flight, as in the first four "test" flights, STS-1 through STS-4. A typical payload capacity is about 22,700 kilograms (50,000 lb), but can be raised depending on the choice of launch configuration. The orbiter carries the payload in a large cargo bay with doors that open along the length of its top, a feature which makes the space shuttle unique among present spacecraft. This feature made possible the deployment of large satellites such as the Hubble Space Telescope, and also to capture and return large payloads back to Earth.

When the orbiter's space mission is complete it fires its Orbital Maneuvering System (OMS) thrusters to drop out of orbit and re-enter the lower atmosphere.[4] During the descent, the shuttle orbiter passes through different layers of the atmosphere and decelerates from hypersonic speed primarily by aerobraking. In the lower atmosphere and landing phase, it acts as a glider with reaction control system (RCS) thrusters and fly-by wire controlled hydraulically actuated flight surfaces controlling its descent. It then makes a landing on a long runway as a spaceplane. The aerodynamic shape is a compromise between the demands of radically different speeds and air pressures during re-entry, subsonic atmospheric flight, and hypersonic flight. As a result the orbiter has a high sink rate at low altitudes, and transitions from using RCS thrusters in low pressure to flight surfaces at low altitudes.

Satellite Modules

The satellite’s functional versatility is imbedded within its technical components and its operations characteristics. Looking at the “anatomy” of a typical satellite, one discovers two modules. Note that some novel architectural concepts such as Fractionated Spacecraft somewhat upset this taxonomy.

Spacecraft bus or service module

This bus module consist of the following subsystems:

  • The Structural Subsystems

The structural subsystem provides the mechanical base structure, shields the satellite from extreme temperature changes and micro-meteorite damage, and controls the satellite’s spin functions.

  • The Telemetry Subsystems (aka Command and Data Handling, C&DH)

The telemetry subsystem monitors the on-board equipment operations, transmits equipment operation data to the earth control station, and receives the earth control station’s commands to perform equipment operation adjustments.

  • The Power Subsystems

The power subsystem consists of solar panels and backup batteries that generate power when the satellite passes into the earth’s shadow. Nuclear power sources (Radioisotope thermoelectric generators) have been used in several successful satellite programs including the Nimbus program (1964-1978).

  • The Thermal Control Subsystems

The thermal control subsystem helps protect electronic equipment from extreme temperatures due to intense sunlight or the lack of sun exposure on different sides of the satellite’s body (e.g. Optical Solar Reflector)

  • The Attitude and Orbit Controlled Control Subsystems

The attitude and orbit controlled subsystem consists of small rocket thrusters that keep the satellite in the correct orbital position and keep antennas positioning in the right directions.

Communication payload

The second major module is the communication payload, which is made up of transponders. A transponders is capable of :

  • Receiving uplinked radio signals from earth satellite transmission stations (antennas).
  • Amplifying received radio signals
  • Sorting the input signals and directing the output signals through input/output signal multiplexers to the proper downlink antennas for retransmission to earth satellite receiving stations (antennas).

End of life

When satellites reach the end of their mission, satellite operators have the option of de-orbiting the satellite, leaving the satellite in its current orbit or moving the satellite to a graveyard orbit. Historically, due to budgetary constraints at the beginning of satellite missions, satellites were rarely designed to be de-orbited. One example of this practice is the satellite Vanguard 1. Launched in 1958, Vanguard 1, the 4th manmade satellite put in Geocentric orbit, was still in orbit as of August 2009.

Instead of being de-orbited, most satellites are either left in their current orbit or moved to a graveyard orbit. As of 2002, the FCC now requires all geostationary satellites to commit to moving to a graveyard orbit at the end of their operational life prior to launch.

Launch-capable countries

Launch of the first British Skynet military satellite.

This list includes countries with an independent capability to place satellites in orbit, including production of the necessary launch vehicle. Note: many more countries have the capability to design and build satellites — which relatively speaking, does not require much economic, scientific and industrial capacity — but are unable to launch them, instead relying on foreign launch services. This list does not consider those numerous countries, but only lists those capable of launching satellites indigenously, and the date this capability was first demonstrated. Does not include consortium satellites or multi-national satellites.

First launch by country
Order ↓ Country ↓ Year of first launch ↓ Rocket ↓ Satellite ↓
1 Soviet Union 1957 Sputnik-PS Sputnik 1
2 United States 1958 Juno I Explorer 1
3 France 1965 Diamant Astérix
4 Japan 1970 Lambda-4S Ōsumi
5 China 1970 Long March 1 Dong Fang Hong I
6 United Kingdom 1971 Black Arrow Prospero X-3
7 India 1980 SLV Rohini
8 Israel 1988 Shavit Ofeq 1
- Russia[1] 1992 Soyuz-U Kosmos-2175
- Ukraine[1] 1992 Tsyklon-3 Strela (x3, Russian)
9 Iran 2009 Safir-2 Omid


  1. Russia and Ukraine were parts of the Soviet Union and thus inherited their launch capability without the need to develop it indigenously. Through Soviet Union they also are on the number one position in this list of accomplishments.
  2. France, United Kingdom launched their first satellites by own launchers from foreign spaceports.
  3. North Korea (1998) and Iraq (1989) have claimed orbital launches (satellite and warhead accordingly), but these claims are unconfirmed.
  4. In addition to the above, countries such as South Africa, Spain, Italy, Germany, Canada, Australia, Argentina, Egypt and private companies such as OTRAG, have developed their own launchers, but have not had a successful launch.
  5. As of 2009, only eight countries from the list above ( Russia and Ukraine instead of USSR, also USA, Japan, China, India, Israel, and Iran) and one regional organization (the European Space Agency, ESA) have independently launched satellites on their own indigenously developed launch vehicles. (The launch capabilities of the United Kingdom and France now fall under the ESA.)
  6. Several other countries, including South Korea, Brazil, Pakistan, Romania, Taiwan, Indonesia, Kazakhstan, Australia, Malaysia[citation needed] and Turkey, are at various stages of development of their own small-scale launcher capabilities.
  7. South Korea launched a KSLV rocket (created with assistance of Russia) in 25 August 2009, but it failed to put satellite STSAT-2 into precise orbit and the satellite did not start to function.
  8. North Korea claimed a launch in April 2009, but U.S. and South Korean defense officials and weapons experts later reported that the rocket failed to send a satellite into orbit, if that was the goal. The United States, Japan and South Korea believe this was actually a ballistic missile test, which is a claim also made after North Korea's 1998 satellite launch, and later rejected.

Launch capable private entities

On September 28, 2008, the private aerospace firm SpaceX successfully launched its Falcon 1 rocket in to orbit. This marked the first time that a privately built liquid-fueled booster was able to reach orbit. The rocket carried a prism shaped 1.5 m (5 ft) long payload mass simulator that was set into orbit. The dummy satellite, known as Ratsat, will remain in orbit for between five and ten years before burning up in the atmosphere.

First satellites of countries

First satellites of countries including launched indigenously or by help of other
Country ↓ Year of first launch ↓ First satellite ↓ Payloads in orbit in 2008[23] ↓
Soviet Union
( Russia)
Sputnik 1
United States 1958 Explorer 1 1042
United Kingdom 1962 Ariel 1 0025
Canada 1962 Alouette 1 0025
Italy 1964 San Marco 1 0014
France 1965 Astérix 0044
Australia 1967 WRESAT 0011
Germany 1969 Azur 0027
Japan 1970 Ōsumi 0123
China 1970 Dong Fang Hong I 0083
Poland 1973 Intercosmos Kopernikus 500 0000?
Netherlands 1974 ANS 0005
Spain 1974 Intasat 0009
India 1975 Aryabhata 0034
Indonesia 1976 Palapa A1 0010
Czechoslovakia 1978 Magion 1 0005
Bulgaria 1981 Intercosmos Bulgaria 1300 0001
Brazil 1985 Brasilsat A1 0011
Mexico 1985 Morelos 1 0007
Sweden 1986 Viking 0011
Israel 1988 Ofeq 1 0007
Luxembourg 1988 Astra 1A 0015
Argentina 1990 Lusat 0010
Pakistan 1990 Badr-1 0005
South Korea 1992 Kitsat A 0010
Portugal 1993 PoSAT-1 0001
Thailand 1993 Thaicom 1 0006
Turkey 1994 Turksat 1B 0005
Ukraine 1995 Sich-1 0006
Chile 1995 FASat-Alfa 0001
Malaysia 1996 MEASAT 0004
Norway 1997 Thor 2 0003
Philippines 1997 Mabuhay 1 0002
Egypt 1998 Nilesat 101 0003
Singapore 1998 ST-1 0001
Taiwan 1999 ROCSAT-1 00009
Denmark 1999 Ørsted 0004
South Africa 1999 SUNSAT 0001
Saudi Arabia 2000 Saudisat 1A 0012
United Arab Emirates 2000 Thuraya 1 0003
Morocco 2001 Maroc-Tubsat 0001
Algeria 2002 Alsat 1 0001
Greece 2003 Hellas Sat 2 0002
Nigeria 2003 Nigeriasat 1 0002
Iran 2005 Sina-1 0004
Kazakhstan 2006 KazSat 1 0001
Belarus 2006 BelKA 0001
Colombia 2007 Libertad 1 0001
Vietnam 2008 VINASAT-1 0001
Venezuela 2008 Venesat-1 0001
Turkey 2009 ITUpSAT1[24] 0001
Switzerland 2009 SwissCube-1[25] 0001

While Canada was the third country to build a satellite which was launched into space, it was launched aboard a U.S. rocket from a U.S. spaceport. The same goes for Australia, who launched on-board a donated Redstone rocket. The first Italian-launched was San Marco 1, launched on 15 December 1964 on a U.S. Scout rocket from Wallops Island (VA,USA) with an Italian Launch Team trained by NASA. Australia's launch project (WRESAT) involved a donated U.S. missile and U. S. support staff as well as a joint launch facility with the United Kingdom.[28]

Attacks on satellites

In recent times satellites have been hacked by militant organizations to broadcast propaganda and to pilfer classified information from military communication networks.

Satellites in low earth orbit have been destroyed by ballistic missiles launched from earth. Russia, the United States and China have demonstrated the ability to eliminate satellites. In 2007 the Chinese military shot down an aging weather satellite, followed by the US Navy shooting down a defunct spy satellite in February 2008.


Due to the low received signal strength of satellite transmissions they are prone to jamming by land-based transmitters. Such jamming is limited to the geographical area within the transmitter's range. GPS satellites are potential targets for jamming, but satellite phone and television signals have also been subjected to jamming. It is trivial to transmit a carrier to a geostationary satellite and thus interfere with any other users of the transponder. It is common on commercial satellite space for earth stations to transmit at the wrong time or on the wrong frequency and dual illuminate the transponder rendering the frequency unusable. Satellite operators now have sophisticated monitoring that enables them to pin point the source of any carrier and manage the transponder space effectively.