Delta IV is a group of five
expendable launch system
An expendable launch system (or expendable launch vehicle/ELV) is a launch vehicle that can be launched only once, after which its components are either destroyed during reentry or discarded in space. ELVs typically consist of several rocket sta ...
s in the
Delta rocket family introduced in the early 2000s. Originally designed by
Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
's Defense, Space and Security division for the
Evolved Expendable Launch Vehicle
National Security Space Launch (NSSL) — formerly Evolved Expendable Launch Vehicle (EELV) from 1994 to 2019 — is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and ...
(EELV) program, the Delta IV became a
United Launch Alliance
United Launch Alliance (ULA), legally United Launch Alliance, LLC, is an American spacecraft launch service provider that manufactures and operates a number of rocket vehicles that are capable of launching spacecraft into orbits around Earth, a ...
(ULA) product in 2006. The Delta IV is primarily a launch vehicle for
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
(USAF) military payloads, but has also been used to launch a number of United States government non-military payloads and a single commercial satellite.
The Delta IV originally had two main versions which allowed the family to cover a range of payload sizes and masses: the retired Medium (which had four configurations) and
Heavy
Heavy may refer to:
Measures
* Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight
* Heavy, a characterization of objects with substantial weight
* Heavy, ...
. As of 2019, only the Heavy remains active, with payloads that would previously fly on Medium moving to either the existing
Atlas V
Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by United Launch Alliance (ULA), a joint venture be ...
or the forthcoming
Vulcan
Vulcan may refer to:
Mythology
* Vulcan (mythology), the god of fire, volcanoes, metalworking, and the forge in Roman mythology
Arts, entertainment and media Film and television
* Vulcan (''Star Trek''), name of a fictional race and their home p ...
. Retirement of the Delta IV is anticipated in 2024.
, two flights remain.
Delta IV vehicles are built in the ULA facility in
Decatur, Alabama
Decatur (dɪˈkeɪtə(r)) is the largest city and county seat of Morgan County (with a portion also in Limestone County) in the U.S. state of Alabama. Nicknamed "The River City", it is located in northern Alabama on the banks of Wheeler Lake ...
. Final assembly is completed at the launch site by ULA: at the
horizontal integration facility for launches from
SLC-37B
Space Launch Complex 37 (SLC-37), previously Launch Complex 37 (LC-37), is a launch complex on Cape Canaveral Space Force Station, Florida. Construction began in 1959 and the site was accepted by NASA to support the Saturn I program in 1963. The ...
pad at
Cape Canaveral
, image = cape canaveral.jpg
, image_size = 300
, caption = View of Cape Canaveral from space in 1991
, map = Florida#USA
, map_width = 300
, type =Cape
, map_caption = Location in Florida
, location ...
and in a similar facility for launches from
SLC-6 pad at
Vandenberg Air Force Base Vandenberg may refer to:
* Vandenberg (surname), including a list of people with the name
* USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...
.
History
The latest evolutionary development of the
Delta rocket family, Delta IV was introduced to meet the requirements of the United States Air Force's (USAF)
Evolved Expendable Launch Vehicle
National Security Space Launch (NSSL) — formerly Evolved Expendable Launch Vehicle (EELV) from 1994 to 2019 — is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and ...
(EELV, now
National Security Space Launch
National Security Space Launch (NSSL) — formerly Evolved Expendable Launch Vehicle (EELV) from 1994 to 2019 — is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and o ...
(NSSL)) program. While the Delta IV retains the name of the Delta family of rockets, major changes were incorporated. Perhaps the most significant change was the switch from kerosene to
liquid hydrogen
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully li ...
fuel, with new tankage and a new engine required.
During the Delta IV's development, a small variant was considered. This would have featured the
Delta II
Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...
second stage, an optional
Thiokol
Thiokol (variously Thiokol Chemical Corporation(/Company), Morton Thiokol Inc., Cordant Technologies Inc., Thiokol Propulsion, AIC Group, ATK Thiokol, ATK Launch Systems Group; finally Orbital ATK before becoming part of Northrop Grumman) was an ...
Star 48B
The Star 48 is the largest of a family of solid rocket motors used by many space propulsion and launch vehicle stages. It is used almost exclusively as an upper stage. It was developed primarily by Thiokol Propulsion and is now, after several m ...
third stage, and the Delta II payload fairing, all atop a single
Common Booster Core
The Common Booster Core (CBC) is an American rocket stage, which is used on the Delta IV rocket as part of a modular rocket system. Delta IV rockets flying in the retired Medium and Medium+ configurations each used a single Common Booster Core as ...
(CBC). The Small variant was dropped by 1999.
In 2002, the Delta IV was first launched, with the
RS-68
The Aerojet Rocketdyne RS-68 (Rocket System 68) is a liquid-fuel rocket engine that uses liquid hydrogen (LH2) and liquid oxygen (LOX) as propellants in a gas-generator power cycle. It is the largest hydrogen-fueled rocket engine ever flown.
I ...
becoming the first large
liquid-propellant rocket
A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid rocket propellant, liquid propellants. Liquids are desirable because they have a reasonably high density and high Specific impulse, specific impulse (''I''sp). T ...
engine designed in the United States since the
Space Shuttle main engine
The Aerojet Rocketdyne RS-25, also known as the Space Shuttle Main Engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is currently used on the Space Launch System (SLS).
Designed and manufacture ...
(SSME) in the 1970s.
The
L3 Technologies
L3 Technologies, formerly L-3 Communications Holdings, was an American company that supplied command and control, communications, Intelligence (information gathering), intelligence, surveillance and reconnaissance (C3ISR) systems and products, ...
Redundant Inertial Flight Control Assembly (RIFCA) guidance system originally used on the Delta IV was common to that carried on the
Delta II
Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...
, although the software was different because of the differences between the Delta II and Delta IV. The RIFCA featured six
ring laser gyroscope
A ring laser gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path; the difference in phase is used to detect rotation. It operates on the principle of the Sagnac effect which shifts ...
s and
accelerometer
An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...
s each, to provide a higher degree of reliability.
Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
initially intended to market Delta IV commercial launch services. However, the Delta IV entered the space launch market when global capacity was already much higher than demand. Furthermore, as an unproven design it had difficulty finding a market in commercial launches, and Delta IV launch costs are higher than comparable vehicles of the same era. In 2003, Boeing pulled the Delta IV from the commercial market, citing low demand and high costs. In 2005, Boeing stated that it sought to return the Delta IV to commercial service.
As of 2009, the USAF funded Delta IV EELV engineering, integration, and infrastructure work through contracts with Boeing Launch Services (BLS). On 8 August 2008, the USAF
Space and Missile Systems Center
Space Systems Command (SSC) is the United States Space Force's space development, acquisition, launch, and logistics field command. It is headquartered at Los Angeles Air Force Base, California and manages the United States' space launch ...
increased the "cost plus award fee" contract with BLS for US$1.656 billion to extend the period of performance through the 30 September 2008 (
FY09). In addition a US$557.1 million option was added to cover FY10.
In February 2010, naturalized citizen Dongfan Chung, an engineer working with Boeing, was the first person convicted under the
Economic Espionage Act of 1996
The Economic Espionage Act of 1996 () was a 6 title Act of Congress dealing with a wide range of issues, including not only industrial espionage (''e.g.'', the theft or misappropriation of a trade secret and the National Information Infrastructu ...
. Chung passed on classified information on designs including the Delta IV rocket to China and was sentenced to 15 years.
In March 2015, ULA announced plans to phase out the Delta IV Medium by 2018.
With the exception of the first launch, which carried the
Eutelsat W5
Eutelsat 33B, formerly known as Eutelsat 3F1, Eutelsat W1, Eutelsat W5, Eutelsat 70A and Eutelsat 25C, is a telecommunications satellite owned by Eutelsat Consortium. Eutelsat W5 provides coverage to Europe, Middle East, and Asia. The satellite ...
commercial communications satellite, all Delta IV launches have been paid for by the US government. In 2015, ULA stated that a
Delta IV Heavy
The Delta IV Heavy (Delta 9250H) is an Evolved Expendable Launch Vehicle, expendable heavy-lift launch vehicle, the largest type of the Delta IV family. It is the world's third highest-capacity launch vehicle in operation, behind NASA's Space L ...
is sold for nearly US$400 million.
RS-68A booster engine upgrade
The possibility of a higher performance Delta IV was first proposed in a 2006
RAND Corporation
The RAND Corporation (from the phrase "research and development") is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed ...
study of national security launch requirements out to 2020. A single
National Reconnaissance Office
The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. f ...
(NRO) payload required an increase in the lift capability of the Delta IV Heavy. Lift capacity was increased by developing the higher-performance
RS-68A
The Aerojet Rocketdyne RS-68 (Rocket System 68) is a liquid-fuel rocket engine that uses liquid hydrogen (LH2) and liquid oxygen (LOX) as propellants in a Gas-generator cycle (rocket), gas-generator power cycle. It is the largest hydrogen-fueled ...
engine, which first flew on 29 June 2012.
ULA phased out the baseline RS-68 engine with the launch of Delta flight 371 on 25 March 2015. All following launches have used the RS-68A,
and the engine's higher thrust allowed the use of a single standardized CBC design for all Delta IV Medium and M+ versions. This upgrade reduced cost and increased flexibility, since any standardized CBC could be configured for zero, two, or four
solid-propellant rocket
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses Rocket propellant#Solid chemical propellants, solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were u ...
boosters. However, the new CBC led to a slight performance loss for most medium configurations. The Delta IV Heavy still requires non-standard CBCs for the core and boosters.
;Launch system status:
Payload capacities after RS-68A upgrade
Payload capacities with original RS-68
*Masses include a Payload Attach Fitting (240 kg to 1,221 kg depending on payload).
Proposed upgrades that were not implemented
Possible future upgrades for the Delta IV included adding extra strap-on solid motors, higher-thrust main engines, lighter materials, higher-thrust second stages, more (up to eight) strap-on CBCs, and a cryogenic propellant cross feed from strap on boosters to the common core.
At one point NASA planned to use Delta IV or Atlas V to launch the proposed
Orbital Space Plane
The Orbital Space Plane (OSP) program was a NASA spaceplane concept in the early 2000s designed to support the International Space Station requirements for crew rescue, crew transport and contingency cargo transport. It was part of the Space Lau ...
, which eventually became the
Crew Exploration Vehicle
The Crew Exploration Vehicle (CEV) was a component of the U.S. NASA Vision for Space Exploration plan. A competition was held to design a spacecraft that could carry humans to the
destinations envisioned by the plan. The winning design was th ...
and then the
Orion. Orion was intended to fly on the
Ares I
Ares I was the crew launch vehicle that was being developed by NASA as part of the Constellation program. The name "Ares" refers to the Greek deity Ares, who is identified with the Roman god Mars. Ares I was originally known as the "Crew Launch ...
launch vehicle, then the
Space Launch System
The Space Launch System (SLS) is an American super heavy-lift expendable launch vehicle developed by NASA. As of 2022, SLS has the highest payload capacity of any rocket in operational service, as well as the greatest liftoff thrust of any r ...
after Ares I was cancelled.
In 2009,
The Aerospace Corporation
The Aerospace Corporation is an American nonprofit corporation that operates a federally funded research and development center (FFRDC) in El Segundo, California. The corporation provides technical guidance and advice on all aspects of space mi ...
reported on
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
results of a study to determine the feasibility of modifying Delta IV to be
crew-rated for use in NASA
human spaceflight
Human spaceflight (also referred to as manned spaceflight or crewed spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be ...
missions. According to
Aviation Week & Space Technology
''Aviation Week & Space Technology'', often abbreviated ''Aviation Week'' or ''AW&ST'', is the flagship magazine of the Aviation Week Network. The weekly magazine is available in print and online, reporting on the aerospace, defense and aviati ...
the study, "found that a Delta IV heavy
..could meet NASA's requirements for getting humans to low Earth orbit".
A proposed upgrade to the Delta IV family was the addition of extra solid motors. The Medium+ (4,4) would have used existing mount points to pair the four GEM 60s of the M+ (5,4) with the upper stage and fairing of the (4,2). An M+ (4,4) would have had a GTO payload of , a LEO payload of , and could have been available within 36 months of the first order. It was also considered to add extra GEM 60s to the M+ (5,4), which would have required adding extra attachment points, structural changes to cope with the different flight loads, and launch pad and infrastructure changes. The Medium+ (5,6) and (5,8) would have flown with six and eight SRBs respectively, for a maximum of up to to GTO with the M+ (5,8). The Medium+ (5,6) and (5,8) could have been available within 48 months of the first order.
Successors
The
Vulcan Centaur
Vulcan Centaur is a two-stage-to-orbit, heavy-lift launch vehicle that is under development by the United Launch Alliance (ULA) since 2014 with an initial flight expected in early 2023. It is principally designed to meet launch demands for the ...
is planned to replace the
Atlas V
Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by United Launch Alliance (ULA), a joint venture be ...
and Delta IV rockets. Vulcan Centaur is projected to enter service by 2023, using the
BE-4
The Blue Engine 4 or BE-4 is an oxygen-rich liquefied-methane-fueled staged-combustion rocket engine under development by Blue Origin. The BE-4 is being developed with private and public funding. The engine has been designed to produce of thr ...
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
-fueled rocket engine. The Delta IV Heavy and Atlas V are expected to stay in service for a few years after Vulcan's inaugural launch, and the Heavy is expected to be discontinued by 2024.
Vehicle description
Delta IV Medium
The Delta IV Medium (also referred to as 'single stick') was available in four configurations: Medium, Medium+ (4,2), Medium+ (5,2), and Medium+ (5,4).
The Delta IV Medium (Delta 9040) was the most basic Delta IV. It featured a single CBC and a modified
Delta III
Delta III was an expendable launch vehicle made by Boeing. The vehicle was developed from the highly-successful Delta II to help meet the launch demand of larger satellites. The first Delta III launch was on August 26, 1998. Of its three flights ...
second stage, with 4-meter liquid hydrogen and liquid oxygen tanks (called a
Delta Cryogenic Second Stage
The Delta Cryogenic Second Stage (DCSS) is a family of cryogenic rocket stages used on the Delta III and Delta IV rockets, and on the Space Launch System Block 1. The stage consists of a cylindrical liquid hydrogen (LH2) tank structurally separate ...
(DCSS)) and a 4-meter payload fairing. The Delta IV Medium was capable of launching 4,200 kg to
geostationary transfer orbit
A geosynchronous transfer orbit or geostationary transfer orbit (GTO) is a type of geocentric orbit. Satellite, Satellites that are destined for geosynchronous orbit, geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into ...
(GTO). From Cape Canaveral, GTO is 1804 m/s away from GEO. The mass of fairing and payload attach fittings have been subtracted from the gross performance.
The Delta IV Medium+ (4,2) (Delta 9240) had the same CBC and DCSS as the Medium, but with the addition of two
Orbital ATK
Northrop Grumman Innovation Systems (NGIS) was a sector (business segment) of Northrop Grumman from 2018 through 2019. It was formed from Orbital ATK Inc. a company which resulted from the merger of Orbital Sciences Corporation and parts of Alli ...
-built 1.5-m (60-in) diameter
solid rocket booster
A solid rocket booster (SRB) is a large solid propellant motor used to provide thrust in spacecraft launches from initial launch through the first ascent. Many launch vehicles, including the Atlas V, SLS and space shuttle, have used SRBs to give ...
Graphite-Epoxy Motor
The Graphite-Epoxy Motor (GEM) is a family of solid rocket boosters first developed in the late 1980s and used from 1990 to the present day. GEM motors are manufactured with carbon-fibre-reinforced polymer casings and a fuel consisting of HTPB-b ...
s (GEM 60s)
strap-on booster
A booster rocket (or engine) is either the first stage of a multistage launch vehicle, or else a shorter-burning rocket used in parallel with longer-burning sustainer rockets to augment the space vehicle's takeoff thrust and payload capability ...
s to increase payload capacity to 6,150 kg to GTO.
The Delta IV Medium+ (5,2) (Delta 9250) was similar to the Medium+ (4,2), but had a 5-m–diameter DCSS and payload fairing for larger payloads. Because of the extra weight of the larger payload fairing and second stage, the Medium+ (5,2) could launch 5,072 kg to GTO.
The Delta IV Medium+ (5,4) (Delta 9450) was similar to the Medium+ (5,2), but used four GEM 60s instead of two, enabling it to lift 6,882 kg to GTO.
To encapsulate the satellite payload, a variety of different payload fairings were available. A stretched Delta III 4-meter diameter composite payload fairing was used on 4-meter Medium versions, while an enlarged, 5-meter diameter composite fairing was used on 5-meter Medium versions.
[
The Medium (4,2) version last flew on 22 August 2019, marking the retirement of the Delta IV Medium variants.]
Delta IV Heavy
The Delta IV Heavy (Delta 9250H) combines a diameter DCSS and payload fairing with two additional CBCs. These are strap-on boosters which are separated earlier in the flight than the center CBC. As of 2007, a longer 5 meter diameter composite fairing was standard on the Delta IV Heavy, with an aluminum isogrid fairing also available. The aluminum trisector (three-part) fairing was built by Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
and derived from a Titan IV
Titan IV was a family of heavy-lift space launch vehicles developed by Martin Marietta and operated by the United States Air Force from 1989 to 2005. Launches were conducted from Cape Canaveral Air Force Station, Florida and Vandenberg Air For ...
fairing. The trisector fairing was first used on the DSP-23 flight. The Delta IV with the extended fairing is over tall.
Common Booster Core
Each Delta IV consists of at least one Common Booster Core
The Common Booster Core (CBC) is an American rocket stage, which is used on the Delta IV rocket as part of a modular rocket system. Delta IV rockets flying in the retired Medium and Medium+ configurations each used a single Common Booster Core as ...
(CBC). Each CBC is powered by one Aerojet Rocketdyne
Aerojet Rocketdyne is an American manufacturer of rocket, Hypersonic flight, hypersonic, and electric propulsive systems for space, defense, civil and commercial applications. Headquartered in Sacramento, California, the company is owned by Aeroj ...
RS-68
The Aerojet Rocketdyne RS-68 (Rocket System 68) is a liquid-fuel rocket engine that uses liquid hydrogen (LH2) and liquid oxygen (LOX) as propellants in a gas-generator power cycle. It is the largest hydrogen-fueled rocket engine ever flown.
I ...
engine, which burns liquid hydrogen
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.
To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully li ...
and liquid oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
.
On flights of the Medium, the RS-68 ran at 102% rated thrust for the first few minutes of flight, and then throttled down to 58% rated thrust before main engine cutoff. On the Heavy, the main CBC's engine throttles down to 58% rated thrust around 50 seconds after liftoff, while the strap-on CBCs remain at 102%. This conserves propellant and allows the main CBC to burn after booster separation. After the strap-on CBCs separate, the main CBC's engine again throttles up to 102% before throttling back down to 58% prior to main engine cutoff.
The RS-68 engine is mounted to the lower thrust structure of the CBC by a four-legged (quadrapod
A quadrapod is a machine (robot) with
four legs for locomotion, for example walking machines.
See also
* Quadruped
Quadrupedalism is a form of locomotion where four limbs are used to bear weight and move around. An animal or machine that ...
) thrust frame and enclosed in a protective composite conical thermal shield. Above the thrust structure is an aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
isogrid
Isogrid is a type of partially hollowed-out structure formed usually from a single metal plate (or face sheet) with triangular integral stiffening ribs (often called stringers). It was patented by McDonnell Douglas (now part of Boeing).
It is extr ...
(a grid pattern machined out of the inside of the tank to reduce weight) liquid hydrogen tank, followed by a composite
Composite or compositing may refer to:
Materials
* Composite material, a material that is made from several different substances
** Metal matrix composite, composed of metal and other parts
** Cermet, a composite of ceramic and metallic materials
...
cylinder called the centerbody, an aluminum isogrid liquid oxygen tank, and a forward skirt. Along the back of the CBC is a cable tunnel to hold electrical and signal lines, and a feedline to carry the liquid oxygen to the RS-68 from the tank. The CBC is of a constant, diameter.[
]
Delta Cryogenic Second Stage
The upper stage of the Delta IV is the Delta Cryogenic Second Stage
The Delta Cryogenic Second Stage (DCSS) is a family of cryogenic rocket stages used on the Delta III and Delta IV rockets, and on the Space Launch System Block 1. The stage consists of a cylindrical liquid hydrogen (LH2) tank structurally separate ...
(DCSS). The DCSS is based on the Delta III
Delta III was an expendable launch vehicle made by Boeing. The vehicle was developed from the highly-successful Delta II to help meet the launch demand of larger satellites. The first Delta III launch was on August 26, 1998. Of its three flights ...
upper stage but has increased propellant capacity. Two versions have been produced: a diameter DCSS that was retired with the Delta IV Medium and a diameter DCSS that remains in service with the Delta IV Heavy. The 4 m diameter version lengthened both Delta III propellant tanks, while the 5-meter version has an extended diameter liquid hydrogen tank and a further lengthened liquid oxygen tank. Regardless of the diameter, each DCSS is powered by one RL10B-2 engine, with an extendable carbon-carbon nozzle to improve specific impulse. Two different interstages are used to mate the first stage and DCSS. A tapering interstage that narrowed down from 5 m to 4 m diameter was used to mate the 4 m DCSS to the CBC, while a cylindrical interstage is used to mate the 5 m DCSS. Both interstages were built from composites and enclosed the liquid oxygen tank, with the larger liquid hydrogen tank making up part of the vehicle's outer mold line.
Launch sites
Delta IV launches occur from either of two rocket launch complexes. Launches on the East coast of the United States use Space Launch Complex 37 (SLC-37) at the Cape Canaveral Air Force Station
Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida.
Headquartered at the nearby Patrick Space Force Base, the statio ...
. On the West coast, polar-orbit and high-inclination launches use Vandenberg Air Force Base Vandenberg may refer to:
* Vandenberg (surname), including a list of people with the name
* USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...
's Space Launch Complex 6 (SLC-6).[
Launch facilities at both sites are similar. A Horizontal Integration Facility (HIF) is situated some distance from the pad. Delta IV CBCs and second stages to be mated and tested in the HIF before they are moved to the pad.][ The partial horizontal rocket assembly of the Delta IV is somewhat similar to the ]Soyuz launch vehicle
The Soyuz (russian: Союз, meaning "union", GRAU index 11A511) was a Soviet expendable carrier rocket designed in the 1960s by OKB-1 and manufactured by State Aviation Plant No. 1 in Kuybyshev, Soviet Union. It was commissioned to launch ...
, which is completely assembled horizontally. The Space shuttles, the past Saturn launch vehicles, and the upcoming Space Launch System
The Space Launch System (SLS) is an American super heavy-lift expendable launch vehicle developed by NASA. As of 2022, SLS has the highest payload capacity of any rocket in operational service, as well as the greatest liftoff thrust of any r ...
are assembled and rolled out to the launch pad entirely vertically.
Movement of the Delta IVs among the various facilities at the pad is facilitated by rubber-tired Elevating Platform Transporters (EPTs) and various transport jigs. Diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
EPTs are used for moving the vehicles from the HIF to the pad, while electric EPTs are used in the HIF, where precision of movement is important.[Delta IV Launch Facilities]
The basic launchpad structure includes a flame trench to direct the engine plume away from the rocket, lightning protection, and propellant storage. In the case of Delta IV, the vehicle is completed on the launch pad inside a building. This Mobile Service Tower (MST) provides service access to the rocket and protection from the weather and is rolled away from the rocket on launch day. A crane at the top of the MST lifts the encapsulated payload to the vehicle and also attached the GEM 60 solid motors for Delta IV Medium launches. The MST is rolled away from the rocket several hours before launch. At Vandenberg, the launch pad also has a Mobile Assembly Shelter (MAS), which completely encloses the vehicle; at CCAFS, the vehicle is partly exposed near its bottom.[
Beside the vehicle is a Fixed Umbilical Tower (FUT), which has two (VAFB) or three (CCAFS) swing arms. These arms carry telemetry signals, electrical power, ]hydraulic
Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...
fluid, environmental control air flow, and other support functions to the vehicle through umbilical lines. The swing arms retract at T-0 seconds once the vehicle is committed to launch.[
Under the vehicle is a Launch Table, with six Tail Service Masts (TSMs), two for each CBC. The Launch Table supports the vehicle on the pad, and the TSMs provide further support and fueling functions for the CBCs. The vehicle is mounted to the Launch Table by a Launch Mate Unit (LMU), which is attached to the vehicle by bolts that sever at launch. Behind the Launch Table is a Fixed Pad Erector (FPE), which uses two long-stroke hydraulic pistons to raise the vehicle to the vertical position after being rolled to the pad from the HIF. Beneath the Launch Table is a flame duct, which deflects the rocket's exhaust away from the rocket or facilities.][
]
Vehicle processing
Delta IV CBCs and DCSSs are assembled at ULA's factory in Decatur, Alabama
Decatur (dɪˈkeɪtə(r)) is the largest city and county seat of Morgan County (with a portion also in Limestone County) in the U.S. state of Alabama. Nicknamed "The River City", it is located in northern Alabama on the banks of Wheeler Lake ...
. They are then loaded onto the R/S ''RocketShip'', a roll-on/roll-off
Roll-on/roll-off (RORO or ro-ro) ships are cargo ships designed to carry wheeled cargo, such as cars, motorcycles, trucks, semi-trailer trucks, buses, trailers, and railroad cars, that are driven on and off the ship on their own wheels or using ...
cargo vessel, and shipped to either launch pad. There, they are offloaded and rolled into a HIF. For Delta IV Medium launches, the CBC and DCSS were mated in the HIF. For Delta IV Heavy launches, the port and starboard strap-on CBCs are also mated in the HIF.[
Various tests are performed, and then the vehicle is rolled horizontally to the pad, where the Fixed Pad Erector (FPE) is used to raise the vehicle to the vertical position. At this time, the GEM 60 solid motors, if any are required, are rolled to the pad and attached to the vehicle. After further testing, the payload (which has already been enclosed in its fairing) is transported to the pad, hoisted into the MST by a crane, and attached to the vehicle. Finally, on launch day, the MST is rolled away from the vehicle, and the vehicle is ready for launch.]
Delta IV launches
Notable launches
The first payload launched with a Delta IV was the ''Eutelsat W5
Eutelsat 33B, formerly known as Eutelsat 3F1, Eutelsat W1, Eutelsat W5, Eutelsat 70A and Eutelsat 25C, is a telecommunications satellite owned by Eutelsat Consortium. Eutelsat W5 provides coverage to Europe, Middle East, and Asia. The satellite ...
'' communications satellite. A Medium+ (4,2) from Cape Canaveral carried the communications satellite into geostationary transfer orbit
A geosynchronous transfer orbit or geostationary transfer orbit (GTO) is a type of geocentric orbit. Satellite, Satellites that are destined for geosynchronous orbit, geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into ...
(GTO) on 20 November 2002.
''Heavy Demo'' was the first launch of the Delta IV Heavy in December 2004 after significant delays due to bad weather. Due to cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, cal ...
in the propellant lines, sensors on all three CBCs registered depletion of propellant. The strap-on CBCs and then core CBC engines shut down prematurely, even though sufficient propellant remained to continue the burn as scheduled. The second stage attempted to compensate for the shutdown and burned until it ran out of propellant. This flight was a test launch carrying a payload of:
*''DemoSat'' 6020 kg; an aluminum cylinder filled with 60 brass rods planned to be carried to GEO; however due to the sensor faults, the satellite did not reach this orbit.
*''NanoSat-2'', carried to low Earth orbit
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...
(LEO) a set of two very small satellites of 24 and 21 kg, nicknamed ''Sparky'' and ''Ralphie'' planned to orbit for one day. Given the under-burn, the two most likely did not reach a stable orbit.
''NROL-22'' was the first Delta IV launched from SLC-6 at Vandenberg Air Force Base Vandenberg may refer to:
* Vandenberg (surname), including a list of people with the name
* USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...
(VAFB). It was launched aboard a Medium+ (4,2) in June 2006 carrying a classified satellite for the U.S. National Reconnaissance Office
The National Reconnaissance Office (NRO) is a member of the United States Intelligence Community and an agency of the United States Department of Defense which designs, builds, launches, and operates the reconnaissance satellites of the U.S. f ...
(NRO).
''DSP-23'' was the first launch of a valuable payload aboard a Delta IV Heavy. This was also the first Delta IV launch contracted by the United Launch Alliance
United Launch Alliance (ULA), legally United Launch Alliance, LLC, is an American spacecraft launch service provider that manufactures and operates a number of rocket vehicles that are capable of launching spacecraft into orbits around Earth, a ...
, a joint venture between Boeing and Lockheed Martin
The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
. The main payload was the 23rd and final Defense Support Program
The Defense Support Program (DSP) is a program of the United States Space Force that operated the reconnaissance satellites which form the principal component of the ''Satellite Early Warning System'' used by the United States.
DSP satellite ...
missile-warning satellite, DSP-23. Launch from Cape Canaveral occurred on 10 November 2007.
''NROL-26'' was the first Delta IV Heavy EELV launch for the NRO. USA 202
USA 202, previously NRO Launch 26 or NROL-26, is a classified spacecraft which is operated by the United States National Reconnaissance Office. It is an Advanced Orion ELINT satellite. According to ''Aviation Week,'' it "fundamentally involves Ame ...
, a classified reconnaissance satellite
A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications.
The ...
, lifted off 18 January 2009.
'' NROL-32'' was a Delta IV Heavy launch, carrying a satellite for NRO. The payload is speculated to be the largest satellite sent into space. After a delay from 19 October 2010, the rocket lifted off on 21 November 2010.
''NROL-49'' lifted off from Vandenberg AFB on 20 January 2011. It was the first Delta IV Heavy mission to be launched out of Vandenberg. This mission was for the NRO and its details are classified.
On 4 October 2012, a Delta IV M+ (4,2) experienced an anomaly in the upper stage's RL10B-2 engine which resulted in lower than expected thrust. While the vehicle had sufficient fuel margins to successfully place the payload, a GPS Block IIF satellite USA-239
USA-239, also known as GPS IIF-3, GPS SVN-65, and Navstar-67 is an American navigation satellite which forms part of the Global Positioning System. It was the third of twelve Block IIF satellites to be launched.
Built by Boeing and launched by U ...
, into its targeted orbit, investigation into the glitch delayed subsequent Delta IV launches and the next Atlas V launch (AV-034) due to commonality between the engines used on both vehicles' upper stages. By December 2012, ULA had determined the cause of the anomaly to be a fuel leak (into the combustion chamber), and Delta IV launches resumed in May 2013. After two more successful launches, further investigation led to the delay of Delta flight 365 with the GPS IIF-5 satellite. Originally scheduled to launch in October 2013, the vehicle lifted off on 21 February 2014.
A Delta IV Heavy launched the Orion spacecraft
Orion (officially Orion Multi-Purpose Crew Vehicle or Orion MPCV) is a Reusable spacecraft, partially reusable crewed spacecraft used in NASA's Artemis program. The spacecraft consists of a Crew Module (CM) space capsule designed by Lockheed ...
on an uncrewed test flight, EFT-1, on 5 December 2014. The launch was originally planned for 4 December 2014, but high winds and valve issues caused the launch to be rescheduled for 5 December 2014.
On August 12, 2018, another Delta IV Heavy launched the Parker Solar Probe
The Parker Solar Probe (PSP; previously Solar Probe, Solar Probe Plus or Solar Probe+) is a NASA space probe launched in 2018 with the mission of making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii (6 ...
on a mission to explore or "touch" the outer corona of the Sun.
The second GPS Block III
GPS Block III (previously Block IIIA) consists of the first ten GPS satellite blocks, GPS III satellites, which will be used to keep the Navstar Global Positioning System operational. Lockheed Martin designed, developed and manufactured the GP ...
satellite was launched with the final Delta IV Medium+ (4,2) configuration on 22 August 2019.
The final flight of the Delta IV, in the heavy configuration, will be NROL-70 which will launch in 2024. It will also be the final flight of the Delta rocket family before it is replaced with the Vulcan
Vulcan may refer to:
Mythology
* Vulcan (mythology), the god of fire, volcanoes, metalworking, and the forge in Roman mythology
Arts, entertainment and media Film and television
* Vulcan (''Star Trek''), name of a fictional race and their home p ...
rocket.
See also
* Comparison of orbital launchers families
This article compares different orbital launcher families (although many launchers that are significantly different from other members of the same 'family' have their own separate entries). The article is organized into two tables: the first tabl ...
* Comparison of orbital launch systems
This comparison of orbital launch systems lists the attributes of all individual rocket configurations designed to reach orbit. A first list contains rockets that are operational or in development as of 2022; a second list includes all retired roc ...
* Advanced Cryogenic Evolved Stage
The Advanced Cryogenic Evolved Stage (ACES) was a proposed liquid oxygen/liquid hydrogen upper-stage from 2005 to 2020 for use on a number of different launch vehicles produced by Boeing, Lockheed Martin, and after a late-2006 merger, United La ...
* Expendable launch system
An expendable launch system (or expendable launch vehicle/ELV) is a launch vehicle that can be launched only once, after which its components are either destroyed during reentry or discarded in space. ELVs typically consist of several rocket sta ...
* List of launch vehicles
References
External links
Delta IV Launch Vehicle page on United Launch Alliance site
Boeing press kit for Heavy Demo launch, 2005
Comparison of Delta IV Heavy with Space Shuttle
First Vandenberg Delta IV Heavy launch video
via EducatedEarth.
* Bates, Jason
Space News, 2004-12-06.
Rocketdyne Space Page
{{DEFAULTSORT:Delta IV
Delta (rocket family)
Decatur, Alabama
Huntington Beach, California
Boeing spacecraft and space launch systems
Military space program of the United States
United Launch Alliance space launch vehicles
Vehicles introduced in 2002