Pegasus rocket on the ground

Pegasus rocket attached to bottom of carrier aircraft

The Pegasus rocket is a winged space booster developed by Orbital Sciences Corporation (Orbital). Three main stages, filled with solid propellant, provide most thrust. The vehicle is launched from another aircraft at approximately 40,000 feet (12,000 m). The vehicle is capable of placing small payloads into low altitude orbits; launch is approximately US$30 million, depending on additional services. Download high resolution version (1426x1126, 1204 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1426x1126, 1204 KB) Wikipedia does not have an article with this exact name. ... Pegasus rocket attached to bottom of carrier aircraft File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Pegasus rocket attached to bottom of carrier aircraft File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Orbital Sciences Corporation (OSC, though commonly abbreviated as Orbital) is a Dulles, Virginia company which specializes in satellite launch and manufacture. ... The second stage of a Minuteman III rocket Description A multistage (or multi-stage) rocket is, like any rocket, propelled by the recoil pressure of the burning gases it emits as it burns fuel. ... The Space Shuttle Columbia is initially launched with the help of solid-fuel boosters Solid rockets are rockets with a motor that uses solid propellants (fuel/oxidizer). ...

Pegasus Program

The Pegasus's three Orion solid motors were originally developed for the cancelled Midgetman, a small ICBM to be launched from a trailer. For Pegasus use, wing and tail assemblies and a payload fairing were developed. Most of the Pegasus was designed by Kris Teaford before going into government contracts. The wing was designed by Burt Rutan. The tail fins provide steering for first-stage flight, as the Orion 50S motor does not have a thrust-vectoring nozzle. Orbital's internal projects, the Orbcomm communications constellation and the OrbView observation satellites, plus Orbcomm-derived satellites (the "Microstar" platform) served as guaranteed customers and additional seed money. A Midgetman test launch The MGM-134 Midgetman was an intercontinental ballistic missile developed by the United States of America. ... A Minuteman III missile soars after a test launch. ... Scaled Composites (often abbreviated as Scaled) was founded in 1982 in Mojave, California by famous aircraft designer Burt Rutan out of what used to be the Rutan Aircraft Factory. ... Thrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine(s) in a direction other than parallel to the vehicles longitudinal axis. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ...

• Mass: 18,500 kg (Pegasus), 23,130 kg (Pegasus XL)
• Length: 16.9 m (Pegasus), 17.6 m (Pegasus XL)
• Diameter: 1.27 m
• Wing span: 6.7 m
• Payload: 443 kg (1.18 m diameter, 2.13 m length)

The first successful Pegasus launch occurred on April 5, 1990. Initially, a NASA-owned B-52 served as the carrier aircraft. After a few years, Orbital transitioned to their "Stargazer" L-1011, a converted airliner. April 5 is the 95th day of the year in the Gregorian calendar (96th in leap years). ... This article is about the year. ... The Lockheed L-1011 TriStar was the third widebody passenger jet airliner to enter operation, following the Boeing 747 and the Douglas DC-10. ...

A Pegasus XL, introduced in 1994 with lengthened stages, provides increased payload. The standard Pegasus has been discontinued; the Pegasus XL is still being produced. Pegasus has flown 37 missions (in both configurations) as of March 22, 2006. Of these, 34 were considered successful launches (see below).

In the Pegasus XL, the first and second stages are lengthened into the Orion 50SXL and Orion 50XL, respectively. Higher stages are unchanged; flight operations are similar.

Dual payloads can be launched, with a canister that encloses the lower spacecraft and mounts the upper spacecraft. The upper spacecraft deploys, the canister splits, then the lower spacecraft separates from the third-stage adapter. Since the fairing is unchanged for cost and aerodynamic reasons, the two payloads must be compact.

For their work in developing the rocket, the Pegasus team led by Dr. Antonio Elias was awarded the 1991 National Medal of Technology by President Bush. The National Medal of Technology is an honor granted by the President of the United States to inventors and innovators that have made significant contributions to the development of new and important technology. ...

Launch Profile

In a Pegasus launch, the carrier aircraft takes off from a runway with support and checkout facilities. Such locations have included Kennedy Space Center, Florida; Vandenberg Air Force Base and Dryden Flight Research Center, California; Wallops Flight Facility, Virginia; Kwajalein Range in the Pacific Ocean, and the Canary Islands in the Atlantic. Merritt Island and Kennedy Space Center The John F. Kennedy Space Center (KSC) is the NASA space vehicle launch facility (spaceport) at Cape Canaveral on Merritt Island in Florida, United States. ... Vandenberg Air Force Base is a base with a spaceport, located in Santa Barbara County, California. ... Dryden Flight Research Centers fleet of aircraft in 1993. ... Wallops Flight Facility Coordinates: Latitude 37. ... Kwajalein Atoll - NASA NLT Landsat 7 (Visible Color) Satellite Image Kwajalein Atoll (Marshallese: Kuwajleen) is part of the Republic of the Marshall Islands (RMI). ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Upon reaching a predetermined staging location and altitude, the aircraft releases the Pegasus. After five seconds of free-fall, the first stage ignites and the vehicle pitches up. The 45-degree delta wing, of composite construction, aids pitch-up and provides some lift. Toward the end of first-stage flight, three small rockets at the bases of the tail fins are ignited. The small rockets swivel with the fins, as the air at altitude has become too thin to give enough steering authority.

Approximately 1 minute and 17 seconds later, the Orion 50S motor burns out. The first stage falls away, taking the wing and tail surfaces, and the second stage ignites. The Orion 50 burns for approximately 1 minute and 18 seconds. Attitude control is by thrust vectoring the Orion 50 motor in two dimensions, pitch and yaw; roll control is provided by the nitrogen thrusters on the third stage. Flight dynamics is the study of orientation of air and space vehicles and how to control the critical flight parameters, typically named pitch, roll and yaw. ...

Midway through second-stage flight, the launcher has reached a near-vacuum altitude. The fairing splits and falls away, uncovering the payload and third stage. Upon burnout of the second stage's motor, the stack coasts until reaching a suitable point in its trajectory, depending on mission. Then the Orion 50 is discarded, and the third stage's Orion 38 motor ignites. It too has a thrust-vectoring nozzle, assisted by the nitrogen thrusters for roll. After approximately 64 seconds, the third stage burns out.

A fourth stage is sometimes added for a higher altitude, finer altitude accuracy, or more complex maneuvers. The HAPS (Hydrazine Auxiliary Propulsion System) is powered by three restartable, monopropellant hydrazine thrusters. As with dual launches, the HAPS cuts into the available volume for payload. A (usually liquid) rocket propellant that can be used by itself, without the need for a second component. ...

Role of the Carrier Aircraft

It may seem at first glance that the carrier aircraft serves as a booster to increase payloads. In fact, air launch is largely used to reduce cost. 40,000 feet is approximately 10% of the minimum altitude needed for a temporarily-stable orbit; it is only 4% of a generally-stable low earth orbit. The airliner is designed for approximately Mach 0.85; this is about 3% of orbital velocity. Mach may refer to: Ernst Mach Mach number, as a measure of speed inertial mass GNU Mach The microkernel on which GNU Hurd is based Mach kernel, an operating systems kernel technology used in Mac OS X Mach band, an optical illusion Mach Five, the name of the car in...

The single biggest cause of launch delays is weather. Carriage to 40,000 feet takes the booster above the troposphere, into the stratosphere. Conventional weather is limited to the troposphere, and crosswinds are much gentler at 40,000 feet. Thus the Pegasus is largely immune to weather-induced delays, and their associated costs, once at altitude. (Severe weather is still avoided during takeoff, ascent, and the transit to the staging point). The Troposphere is the lowermost portion of Earths atmosphere. ... A diagram is needed here to illustrate the stratosphere layer of the Earths atmosphere. ...

Air launching reduces range costs. No blastproof pad, blockhouse, or associated equipment is needed. This allows takeoff from a wide variety of sites, generally limited by the support and preparation requirements of the payload. The range of the aircraft also allows launches from the equator, which increases performance and is a requirement for some missions.

Launch at altitude allows a larger, more efficient, yet cheaper first-stage nozzle. Its expansion ratio can be designed for low ambient air pressures, without risking flow separation and flight instability during low-altitude flight. The extra diameter of the high-altitude nozzle would be difficult to gimbal. But the fins handle first-stage steering, allowing a fixed nozzle, which saves cost and weight versus a hot joint.

The initial altitude also helps indirectly. The three rocket stages were originally designed for a suborbital Midgetman missile launch, where the ascent profile is much less important than overall impulse. Military rockets accelerate quickly, to make detection and interception difficult; their warheads are designed to withstand the high launch loads. Spacecraft, though, are designed as lightly as possible, to maximize usable payload; a stressful launch would destroy them. The extra payload and wing weight of a Pegasus versus a Midgetman reduces early acceleration slightly. Because the Pegasus does not accelerate until thin air has been reached, the dynamic pressure on the payload is lower.

A single-impulse launch results in an elliptical orbit, with a high apogee and low perigee. The use of three stages, plus the coast period between second and third stage firings, help circularize the orbit, ensuring the perigee clears the Earth's atmosphere. If the Pegasus launch had begun at low altitude, the coast period or thrust profile of the stages would have to be modified to prevent skimming of the atmosphere after one pass. Since the thrust profiles were set by the Midgetman's motor designs (which were never intended to make a complete orbit anyway), a coast of up to 45 minutes may have been necessary. This would have increased requirements on the third stage's attitude control and thermal systems, cutting into payload. This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

Launch History

• April 1990- Pegsat, NavySat: Success
• July 1991- Microsats (7 satellites): Success
• February 1993- SCD-1: Success
• April 1993- ALEXIS: Success
• May 1994- STEP-2: Partial success (orbit slightly low)
• June 1994- STEP-1: Failure (destroyed during first-stage flight)
• August 1994- APEX: Success
• April 1995- Orbcomm (2 satellites), OrbView-1: Success
• June 1995- STEP-3: Failure (destroyed between first- and second-stage flight)
• March 1996- REX II: Success
• May 1996- MSTI-3: Success
• July 1996- TOMS: Success
• August 1996- FAST: Success
• November 1996- HETE/SAC-B: Failure (Satellites not ejected from third stage): Success
• April 1997- MiniSat: Success
• August 1997- OrbView-2: Success
• August 1997- FORTE: Success
• October 1997- STEP-4: Success
• December 1997- Orbcomm (8 satellites): Success
• February 1998- SNOE, BATSAT: Success
• April 1998- TRACE: Success: Success
• August 1998- Orbcomm (8 satellites): Success
• September 1998- Orbcomm (8 satellites): Success
• October 1998- SCD-2: Success
• December 1998- SWAS: Success
• March 1999- Wide_Field_Infrared_Explorer (Wide_Field_Infrared_Explorer): Success
• May 1999- Terriers & MUBLCOM: Success
• December 1999- Orbcomm (8 satellites): Success
• June 2000- TSX-5: Success
• October 2000- HETE 2: Success
• March 2002- RHESSI: Success
• January 2003- SORCE: Success
• April 2003- GALEX (Galaxy Evolution Explorer): Success
• June 2003- OrbView-3: Success
• August 2003- SCISAT-1: Success
• April 2005- DART: Success
• March 2006- Space Technology-5 (3 satellites): Success

Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... The High Energy Transient Explorer is an American astronomical satellite. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... It has been suggested that this article or section be merged with Tracing. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ... Orbcomm ORBCOMM is a mobile satellite service provider offering high value, two-way data and message communications globally through international service licensees and in the U.S. through value-added resellers, as well as through direct sales. ... The High Energy Transient Explorer is an American astronomical satellite. ... Reuven Ramaty High Energy Solar Spectroscopic Imager (or RHESSI) is a NASA sixthSmall Explorer, launched on 5 February 2002. ... NASAs DART spacecraft DART, or Demonstration for Autonomous Rendezvous Technology, is a NASA sponsored project. ...

Related Projects

Pegasus components have also been the basis of other OSC launchers. The ground-launched Taurus rocket places the Orion 50 and 38 stages atop a Castor 120 first stage, derived from the first stage of the MX ("Peacekeeper") missile. The initial launches used refurbished MX first stages. Orbital Sciences Corporation (OSC, though commonly abbreviated as Orbital) is a Dulles, Virginia company which specializes in satellite launch and manufacture. ... Taurus is an German/Swedish air-launched cruise missile, manufactured by EADS, Saab Bofors Dynamics and used by Germany and Sweden. ... Test launch of a Peacekeeper ICBM by the 576 Flight Test Squadron, Vandenberg AFB, CA (USAF) The LG-118A Peacekeeper was a land-based ICBM deployed by the United States starting in 1986. ...

The Minotaur, also ground-launched, is a combination of stages from Taurus launchers and Minuteman missiles. The first two stages are from a Minuteman II; the upper stages are Orion 50XL and 38. Due to the use of surplus military rocket motors, it is only used for US Government payloads. The LGM-30 Minuteman is a United States nuclear missile, a land-based intercontinental ballistic missile (ICBM) (the other type is the LG-118A Peacekeeper, which is to be phased out by 2005). ...

The NASA X-43A hypersonic test vehicles were boosted by Pegasus first stages. The upper stages were replaced by exposed models of a scramjet-powered vehicle. The Orion stages boosted the X-43 to its ignition speed and altitude, and were discarded. After firing the scramjet and gathering flight data, the test vehicles also fell into the Pacific. NASA technicians working on the X-43A at the tip of a Pegasus rocket attached to a Boeing B-52B prior to launch (March 27, 2004) The X-43 is an unmanned experimental hypersonic aircraft design with multiple planned scale variations meant to test different aspects of highly supersonic flight. ...

External links

Wikimedia Commons has media related to:

Pegasus (Rocket)

• Encyclopedia Astronautica entry
• Orbital Sciences Corporation page
• Pegasus Rocket page
• Pegasus Mission History