Atlas V

The Atlas V is a U.S. launcher for medium to heavy loads. It provides the latest member of the Atlas rocket family represents the Atlas V was developed by Lockheed Martin and first also built; the maiden flight was successfully completed in August 2002. The launches were marketed until the end of 2006 by the American- Russian company International Launch Services, then this business but was completely transferred to the United Launch Alliance, a joint venture between Lockheed Martin and Boeing. Since this restructuring, the Atlas V is offered almost exclusively to orders of the U.S. government, as the commercial business in previous years did not prove profitable. Thus, the rocket transported today mainly military satellites for the United States Air Force and space probes for NASA. Among the best known payloads include the Mars Reconnaissance Orbiter, New Horizons, the Boeing X -37 space plane and the MAVEN spacecraft.

Features of the Atlas V belongs to their extremely high starting reliability. To this day, there was not a single false start. [Note 1] Further, it is distinguished by its highly modular design. There are a total of 19 different variants are possible. It also works well for missions beyond Earth's orbit since it can achieve a high top speed for the payload. Also worth mentioning is the use of a developed and produced in Russia engine in the main stage.

• 2.1 Designations
• 2.2 Main Level
• 2.3 Booster
• 2.4 upper
• 2.5 payload fairing and adapter 2.5.1 400 series
• 2.5.2 500 Series
• 2.5.3 Multiple Boot Adapter
• 2.5.4 Double -start capability

• 4.1 Versions and payload
• 4.2 Weights and dimensions
• 4.3 engines

• 6.1 External links
• 6.2 Notes
• 6.3 Notes and references

History

Development

The development of the Atlas V began with a request of the U.S. government in 1994. Here, a new support system called the Evolved Expendable Launch Vehicle ( EELV ) should be developed and built. The new rocket should especially much cheaper than in the past to heavy payloads into orbit transport medium, especially in comparison to the Titan IV or into an even more expensive Space Shuttle. Similar to the European Ariane 4, they should also be able to transport a wide range of payload at internationally competitive prices through a modular structure. At the tender responded all major U.S. aerospace company McDonnell Douglas with a further development of the Delta series, Lockheed Martin with an improved Atlas - variant and Boeing and Alliant Technologies with completely new designs (among other things with the SSME engine as a base ). When Boeing bought out McDonnell Douglas in 1996, took over the one offered delta development. To finance presented the Air Force for the preliminary design phase of all four applicants per 30 million U.S. dollars.

Then were both Boeing and Lockheed Martin the contract, each Delta IV and Atlas V which to develop. In this second phase, both companies received an additional 60 million dollars to revise their concepts and submitted to begin the detailed planning.

In October 1998, then began the third and final phase in which both carriers were developed to use maturity. This was associated with the firm commitment of the U.S. Air Force, 9 carried out every 19 starts on the Delta IV and Atlas V on the. Lockheed Martin received thus orders with a total of 1.15 billion U.S. dollars, addition there were subsidies from NASA, which contributed about half of the initial development costs of $ 1.6 billion. As, however, it was announced that Boeing had conducted industrial espionage to gain access to confidential data, the Atlas V, withdrew the Air Force Delta IV seven flights and arranged them to the Atlas, which significantly improved the financial situation of the project. The maiden flight of the rocket in the version of Atlas V ( 401) was held on 21 August 2002. Was transported to the Satellite Hot Bird 6 of the European company Eutelsat.

Start-up costs

Since commercial customers do not publish the modalities of its launch contracts, an accurate determination of the start up costs is not possible. However, NASA has disclosed these costs for some of its Atlas V launch:

Manned missions with the Atlas V

As the end of the service life of the Space Shuttle moved closer, initial studies on suitability of the Atlas V have been carried out for manned missions. Because of the significant high starting reliability Lockheed Martin estimated in 2008, the development time of such a one - rated version for three years. These plans were not initially implemented because the Ares I with Orion spacecraft should serve as a replacement for the Space Shuttle. As the associated Constellation program came to a halt in 2010, was again increased interest in an Atlas V version for human spaceflight. On 12 July 2011, the missile was then officially included in the Commercial Crew Development program of NASA, under which a commercial, private-sector support system should be developed for the transportation of people to the International Space Station. On 8 August of the same year Boeing announced to want to start his under development manned CST -100 capsule in the future with the Atlas V. Initial tests of the system are to be held in 2015. Also, the Dream Chaser by SpaceDev should be started with an Atlas V.

Versions with different payload capacity

Lockheed Martin currently plans for the development of a particularly powerful version of the Atlas V, which is called the Atlas V Heavy Lift Vehicle ( HLV short Atlas V, or sometimes Atlas V Heavy). How to Delta IV Heavy in this side of the central main stage two more opposite liquid-propellant boosters are attached, which correspond in size and structure of the main stage. By this measure, the payload increases compared to the currently most powerful variant, the Atlas V ( 551 ), by about 50 %: For the low earth orbit (LEO ) from 18,814 kg to 29,400 kg, and for a geosynchronous orbit of 8900 kg to 13,000 kg ( see details below). If a customer chooses the Atlas V HLV book, this should be able to be developed and built within 30 months.

An Atlas V version with a payload capacity below the Atlas V ( 401) (probably derived from the Agena ) an Agena upper stage in 2000 called should use instead of the Centaur upper stage, has been deleted. Your transport capacity could have been 3890 kg for a near-earth orbit or 1842 kg for geostationary transfer orbit.

Technology

Designations

An essential feature of Atlas V is its modularity. Therefore, a systematic naming scheme for each variant was introduced, from which the parameters of the rocket can be read:

Note: The payload fairing has a diameter not exactly 4 or 5 meters, but 4.2 and 5.4 meters. For the sake of simplicity, the decimal places are not going but in the designation of the missile. At the 4.2-m fairing the number of boosters is limited to 0-3. Of the 20 possible combinations have been used thus far only nine. The ability to bring a second engine in the upper stage was not been used and the combination 511 not also.

Main stage

The main stage of the Atlas V, which is also called Common Core booster (CCB), performs most of the work to convey the payload, it is the central part and the first stage of the rocket. It is 32.46 meters high, has a diameter of 3.81 m and weighs 286 tons refueled (empty: 21 tons). Their structure consists mainly of aluminum, the oxidizer and fuel tank as opposed to the previous launch vehicles, the Atlas series without internal pressure are stable and self-supporting ( previous Atlas rockets would be no pressure in the tanks during the erection collapsed ). This construction is indeed difficult, but it simplifies the handling during the launch preparations and permits attachment of numerous heavy boosters. Fuel as the favorable RP- 1 mixture is used, which is burned with the liquid oxygen as the oxidizer.

The powerplant is a liquid rocket engine of the RD -180 is used, a modified version of the RD -170, which is so reliable that it is also approved for human spaceflight. It weighs 5480 kg, produces up to 4,152 kN thrust and reached in a vacuum specific impulse of 3,312 m / s The combustion uses the Staged Combustion Principle: The oxidant liquid oxygen flows to the two first main combustion chambers and the nozzles pass to cool them, and then is combusted with a portion of the fuel RP -1 in a small pre-combustion chamber. This creates a large amount of gas, which is used for the operation of a turbine which in turn drives the fuel and oxidizer. However, the gas is still very rich in unburned oxidizer, as in the pre-combustion only a small amount of fuel injected. Therefore, it is finally directed to the two main combustion chambers, in which this gas is burned with the remainder of the fuel efficiently and is ejected at high pressure through the respective nozzle. Advantages of this rather complex process are the compact size and very high thrust potential. Ignition is by means of a hypergolic mixture which ignites on contact and thereby provides the necessary gas for the operation of the pumps and so sets the combustion cycle in motion. This concept is distinguished by its simplicity and reliability, but the engine can only be fired once, but this is not a disadvantage at the first stage of the rocket.

The RD- 180 is produced by the Russian aerospace company NPO Energomash, which provides among other engines for the Soyuz and Proton rockets. In order to offer the engine in the U.S., we entered into a joint venture with Rocketdyne, since 2005 part of Pratt & Whitney, a. Therefore, the RD -180 is officially distributed by the Company as incurred RD Amross.

The flight control by means of the computer systems of the upper stage, the main stage has only facilities for communications, attitude determination and control of the movable nozzle of the RD -180 engine.

Booster

In order to increase the payload, there is the possibility - in addition to the previously located at the planning stage HLV - variant - to complement up to five produced by Aerojet solid rocket boosters. Each of these booster has a diameter of 1.58 m, is 20 m long and weighs 47 tons. The shell is made of lightweight, yet very resilient carbon fiber reinforced plastic, these solid rocket boosters are the biggest components that have ever been made ​​of this material. As fuel comes APCP, a mixture of ammonium perchlorate and aluminum, embedded in HTPB, is used, which develops a thrust of 1690 kN at the start and achieved a specific impulse of 2,696 m / s ( vacuum). For controlling the trajectory of the nozzles can be pivoted by up to 3 °.

Since the solid rocket boosters after they have been fired once, no more can be switched off, they are activated only after a test of the RD -180 engine of the main stage. Should this not have attained its proper operating parameters within 2.7 seconds, the start is aborted. Otherwise, the ignition of the solid rocket boosters marks the point of no return of the mission, because the rocket can be stopped as of this date only by a blast. After about 100 seconds, the fuel is used up and the boosters are jettisoned, so the main stage has to cope with the rest of the flight under its own power.

A special feature of the Atlas V is that the solid rocket boosters are arranged asymmetrically - in contrast to other systems, such as the Delta II Also new is the ability to even use a single booster when needed.

Advanced level

For the Atlas V are two variations of proven Centaur upper stage are available: one with two engines ( dual-engine Centaur, DEC ), which is particularly suitable for heavy loads to start in the Low Earth Orbit (LEO ) and one with only one engine ( Single Engine Centaur SEC), which is optimized for GTO satellites. The upper level is 12.68 m long, in any case, measures 3.05 m in diameter and weighs 23.077 or 23.292 tons, depending on the number of engines. These are of the type RL -10A -4 2 and each weighing 175 kg, produce up to 99 kN of thrust and achieve a specific impulse of 4422 m / s They are designed, built and marketed by Pratt & Whitney.

In contrast to the main stage is used as fuel not RP -1, but liquid hydrogen. Although this (about 20 K), difficult to store and expensive to produce, due to its very low boiling point, but the combustion is more efficient than in RP -1. Oxidant as liquid oxygen is also used. The tanks of the Centaur are not self-supporting as opposed to those of the main stage, so they must be pressurized in order not to collapse. Also, they are not made of aluminum, but stainless steel and are due to the very cold liquid hydrogen insulated with 1.6 cm PVC foam.

The combustion takes place according to the principle of the expander cycle process. Here, the fuel ( liquid hydrogen ) flowing as in the first main stage, past the combustion chamber and the nozzle to cool the former. By the action of heat the liquid hydrogen evaporates abruptly and generates a pressure sufficient to drive the turbine, the fuel and oxidizer directly without further pre-combustion. After the hydrogen gas has passed through the turbine, it passes into the combustion chamber, where it is mixed with the oxidizer ( liquid oxygen ), and finally burnt. This system achieved compared to the staged combustion process of the RD -180 no high thrust levels, but is less complex and more efficient. The ignition is effected by means of a spark generator, the engine can be started even several times.

The position control of the upper level by means of up to 51 cm swing nozzles of the RL -10 engines, and twelve other small thrusters. These are operated with hydrazine, four nozzles have a thrust of 27 N, the remaining eight reach 40 N. The nozzles of the RL -10 engines are in the single-engine version of electro- mechanically, hydraulically pivoted at the twin-engined variant.

Fairing and adapter

Two different systems for the Atlas V payload fairing available to that also affect the connection to the school: the small 400 series and the big 500 series.

400 series

For payloads with a relatively small diameter is a fairing made ​​of aluminum available. This can be extended with one or two sections below the relatively long conical, rounded tip top. Its inner diameter is 3.75 m in the cylindrical part and the extensions 3.7084 m. It has an outer diameter of 4.2 m, is 12 to 13.8 m long and weighs 2127-2487 kg ( see details below). The panel accommodates a payload adapter and is based directly on the Centaur upper. This therefore has two separate adapters that connect it to the main stage. One is made entirely of aluminum, is 0.65 m tall and weighs 182 kg, the other reaches a height of 4.13 m, weighs 947-962 kg (depending on engine number of the upper level) and has a carbon fiber surface is supported by an aluminum structure. These fairings are derived from those of the Atlas III.

500 Series

In order to also carry payloads of large volume, the payload fairing of the 500 series and its ease of Honeycomb construction ( surface of CFRP has been developed which is mainly due to their larger diameter ( 4.572 m inside outside 5.4 m and max. ), support structure made ​​of aluminum ) is characterized. This series includes three different sized versions, which have a length of 20.7 to 26.5 m and a weight 3542-4379 kg ( see details below). In contrast to the 400 series but not the payload fairing is based on the advanced level. This is completely within the panel, so both components are mounted on a common adapter system, which connects it to the main stage. The first adapter, which is expected in its dimensions and weights for cladding, has the form of a downwardly tapering cylinder, takes on the RL -10 engine of the upper stage and reduces the diameter of 5.4 m to 3.83 m. The next adapter is 3.81 m tall, weighs, depending on the engine Number of high school 2212-2227 lbs and is also constructed in honeycomb design. The last little adapter finally makes the connection with the main stage. He is only 0.32 meters tall, weighs 285 kg and is made of aluminum. This fairing has a tip with ogive shape, so that the top of the room for the payload is narrower. This manufactured in Switzerland by RUAG, derived from the Ariane 5 payload fairing is in addition to the engines, the only non -US component of the Atlas V.

Multiple Boot Adapter

For missions which do not exhaust the payload or the available volume of the Atlas V, still a 61 -cm-high adapter can be used in addition, can be attached to the up to six other small satellites. The as " EELV Secondary Payload Adapter" ( ESPA ) designated construction is made of aluminum, weighs 130 kg and is inserted between the primary payload and the Centaur upper stage. The satellite carried must not exceed a weight of about 181 kg, and maximum of 76.2 cm measured in each dimension. The production costs for ESPA be about $ 125,000, a starting place for a small satellite costs depending on the size about 1 to 2 million dollars.

Double -start capability

The Atlas V is from 2017 also can perform starts with two main payloads simultaneously.

Infrastructure

For the Atlas V are two places available: The first is Launch Complex 3 at Vandenberg Air Force Base in California for inclinations from 63.4 °. Also polar and slightly retrograde orbits like the sun-synchronous orbit are possible. The second is Launch Complex 41 on Cape Canaveral Air Force Station in Florida. From there are inclinations of 28.5 ° to 55 °.

In Vandenberg, the rocket in the conventional method is first assembled on the launch platform, while the ratios for U.S. new "clean pad " concept to apply in Cape Canaveral. [Note 2] Here it is, fully assembled the rocket already in a 89 m high building, which is called the Vertical Integration Facility (VIF ) and is half a kilometer away from the launch site. Then it is moved to the launch pad to the launch site, the integrated on the table starting tower is constructed very simply and merely provides a power and data connection and tank systems. After some automated testing and fueling the Atlas V is then ready to start after a few hours.

This clean- pad system offers numerous advantages in launch preparation and risk management. Thus, the assembly protects the missile in a building from harmful environmental influences and facilitates the workers access to the various components. Since the launch site can be made ​​much simpler, the financial loss and the time needed to rebuild after a possible explosion of the rocket on the launch pad are much lower than with the conventional, often highly complex launch facilities. In addition, rockets more often can be started by the more effective operation, up to 15 units per year. These advantages are compared with that additional building for the assembly and storage of components are required. So first had the old launch tower for the Titan III are broken and the associated buildings will be rebuilt for the booster assembly to storage rooms for Atlas V components. In addition, the Vertical Integration Facility had to be rebuilt. Overall, the renovation and construction activities lasted over three years.

Atlas V ( 401) on the home place with the two RBSP satellites. In this picture you can see the back of the launch tower.

The mobile gantry from SLC -3E moves to the park position for the start

Atlas V ( 411 ) next to the complex launch tower SLC -3E

Specifications

Versions and payload

State of the list: 18 September 2013 All data in accordance with United Launch Alliance Atlas V Launch Services - User's Guide (2010 ), pp. 59, unless indicated otherwise.

An explanation of the labeling scheme can be found above.

Parameters for the specified data:

Low Earth Orbit (LEO )

• Start Position: CCAFS
• Inclination: 28.5 °
• Perigee / apogee: 200 km ( orbit )

Sun Synchronous Orbit (SSO )

• Start Position: VAFB
• Perigee / apogee: 200 km ( orbit )

Geosynchronous orbit ( GSO)

• Start Position: CCAFS
• Inclination: 0 °

Geostationary transfer orbit ( GTO)

• Start Position: CCAFS
• DELTA.V to GSO: 1804 m / s
• Inclination: 27.0 °
• Perigee: min. 185 km
• Apogee: 35,786 km

Payload fairing used

• 400 series: Medium length ( 12.9 m)
• 500 Series: Low length ( 20.7 m)
• HLV: Great length ( 26.5 m)

Weights and dimensions

All data in accordance with United Launch Alliance Atlas V Launch Services - User's Guide (2010) made, unless otherwise stated.

Engines

All data according to Lockheed Martin Atlas V Propulsion - Powered by Innovation ( 2006), unless indicated otherwise.

Start list

References