A mobile launcher platform (MLP), also known as mobile launch platform, is a structure used to support a large multistage space vehicle which is assembled (stacked) vertically in an integration facility (e.g. the Vehicle Assembly Building) and then transported by a crawler-transporter (CT) to a launch pad. This becomes the support structure for launch.
The use of mobile launcher platform is a part of the Integrate-Transfer-Launch (ITL) system, which involves vertical assembly, transport, and launch of rockets. The concept was first implemented in the 1960s for the United States Air Force's Titan III rocket, and it was later used by NASA for Saturn V, Space Shuttle, and Space Launch System. [1]
There are alternatives to ITL. Horizontal assembly and transport to the pad is used by Russia, by ULA for the Delta IV family, and by SpaceX for the Falcon 9 family. Vertical assembly on the launch pad is used for smaller launch vehicles and for the SpaceX Starship.
From 1967 to 2011, three platforms were used at the LC-39 to support NASA's launch vehicles. Formerly called Mobile Launchers (ML), the mobile launcher platforms were constructed for transporting and launching the Saturn V rocket for the Apollo program lunar landing missions of the 1960s and 1970s. Each ML originally had a single exhaust vent for the Saturn V's engines. The Mobile Launchers also featured a 380-foot-tall (120 m)Launch Umbilical Tower (LUT) with nine swing arms that permitted servicing of the vehicle on the launch pad, and swung away from it at launch.
The Mobile Launchers were built by Ingalls Iron Works. The swing arms were constructed by Hayes International.
After the Apollo program, the bases of the Mobile Launchers were modified for the Space Shuttle. The Launch Umbilical Towers from ML-2 and ML-3 were removed. Portions of these tower structures were erected at the two launch pads, 39A and 39B. These permanent structures were known as the Fixed Service Structures (FSS). The LUT from ML-1 was taken apart and stored in the Kennedy Space Center's industrial area. Efforts to preserve the LUT in the 1990s failed due to a lack of funding, and it was scrapped. [2]
In addition to removal of the umbilical towers, each Shuttle-era MLP was extensively reconfigured with the addition of two Tail Service Masts (TSM), one on either side of the main engine exhaust vent. These 9.4 m (31 ft) masts contained the feed lines through which liquid hydrogen (LH2) and liquid oxygen (LOX) were loaded into the shuttle's external fuel tank, as well as electrical hookups and flares that were used to burn off any ambient hydrogen vapors at the launch site immediately prior to Main Engine start. [3]
The main engines vented their exhaust through the original opening used for the Saturn rocket exhaust. Two additional exhaust ports were added to vent exhaust from the Space Shuttle Solid Rocket Boosters (SRBs) that flanked the external fuel tank.
The Space Shuttle assembly was held to the MLP at eight holddown points using large studs, four on the aft skirt of each Solid Rocket Booster. Immediately before SRB ignition, frangible nuts attached to the top of these studs were detonated, releasing the Shuttle assembly from the platform. [4]
Each MLP weighed 8.23 million pounds (3,730 tonnes) unloaded and roughly 11 million pounds (5,000 tonnes) with an unfueled Shuttle aboard, measured 160 by 135 feet (49 by 41 m), and was 25 feet (7.6 m) high. They were carried by one of two crawler-transporters (CT), which measure 131 by 114 feet (40 by 35 m), and 20 feet (6.1 m) high. Each crawler weighs about 6 million pounds (2,700 tonnes) unloaded, has a maximum speed of about 1 mile per hour (1.6 km/h) loaded, and has a leveling system designed to keep the launch vehicle vertical while negotiating the 5 percent grade leading to the top of the launch pad. Two 2,750 horsepower (2.05 MW) diesel engines power each crawler. [5]
The MLPs were designed as part of NASA's strategy for vertical assembly and transport of space vehicles. Vertical assembly allows the preparation of the spacecraft in a ready-for-launch position, and avoids the additional step of lifting or craning a horizontally-assembled vehicle onto the launchpad (as the engineers of the Soviet space program chose to do).
Construction of the Mobile Launcher Platform-1 (MLP-1) (formerly called the Mobile Launcher-3 or ML-3) began in 1964 and was completed with the installation of the Launch Umbilical Tower hammerhead crane on 1 March 1965. [6] The swing arms were added at a later date.
The ML-3 was used for five crewed Apollo launches; Apollo 10, Apollo 13, Apollo 15, Apollo 16 and Apollo 17.
Following the launch of Apollo 17, the ML-3 was the first of the Mobile Launchers to be converted for use by the Space Shuttle. The Launch Umbilical Tower was dismantled and later partially reassembled on LC-39A [7] as that pad's Fixed Service Structure (FSS) and the base of the launch platform was modified to accommodate the locations of engines on the Shuttle. The platform was redesignated MLP-1.
In total, the MLP-1 was used for 52 Shuttle launches between 1981 and 2009. It was used for the first Space Shuttle launch, STS-1, in April 1981. Following the launch of STS-119 in March 2009, it was transferred to the Constellation program. The platform was used only for the Ares I-X and the MLP-1 suffered substantial damage. The canceled Ares I-Y would have used the same MLP. [8] [9] However, the Constellation program was canceled and the MLP was left unused.
Following the STS-135, usable parts from the MLP-1 were removed and stored in the Vehicle Assembly Building, with no plans to use the MLP again. [10]
In 2021, NASA began rolling out Mobile Launch Platform-1 on Crawler transporter-2 with a concrete ballast on the top to condition the crawlerway to handle the combined weight of the Space Launch System and Orion spacecraft in the future. [11] NASA stated that re-conditioning of the crawlerway will be required periodically in the future, and MLP-1 will be retained for that purpose. MLP-1 will be stored in High Bay 1 of the Vehicle Assembly Building when not in use for crawlerway maintenance. [12] [13]
Mobile Launcher Platform-2 (MLP-2) (formerly called the Mobile Launcher-2 or ML-2) was used for the uncrewed Apollo 6 mission, followed by three crewed Apollo launches; Apollo 9, Apollo 12 and Apollo 14. It was subsequently used for the launch of Skylab on a Saturn V in 1973.
Following the launch of Skylab, ML-2 was the second of the Mobile Launchers to be converted for use by the Space Shuttle. The Launch Umbilical Tower was dismantled and partially reassembled to become the LC-39B [14] Fixed Service Structure (FSS), and the base of the launch platform was modified to accommodate the locations of engines on the Shuttle. The platform was redesignated MLP-2.
In total, MLP-2 was used for 44 Shuttle launches, starting in 1983. All of the orbiters except Columbia made their maiden flights from MLP-2. It was also the launch site for the ill-fated STS-51L mission, when Space Shuttle Challenger disintegrated shortly after launch, killing all seven crew members. [15]
Following the Space Shuttle retirement, NASA kept the MLP-2 for liquid-propellant rockets, [10] but in January 2021, NASA announced that due to lack of storage space, the massive structure would be demolished. [16]
The first launch from the Mobile Launcher Platform-3 (MLP-3) (formerly called the Mobile Launcher-1 or ML-1) was the maiden flight of the Saturn V, and the first launch from LC-39, Apollo 4. Following this, it was used for two crewed Apollo launches: Apollo 8 and Apollo 11. After NASA decided to move Saturn IB launches from LC-34 to LC-39B, the ML-1 was modified by the addition of a structure known as the Milkstool, which allowed the Saturn IB to use the same Launch Umbilical Tower as the much larger Saturn V. Three crewed flights to Skylab, and the Apollo launch for the Apollo-Soyuz Test Project, were conducted from the ML-1 using the Milkstool.
Prior to the scrapping of the LUT in 2004, there was a campaign to rebuild and preserve it as a memorial to Project Apollo. [17] The crew access arm is preserved at the Kennedy Space Center Visitor Complex on the upper level of the gift shop. [18]
Following the launch of Apollo-Soyuz, ML-1 was the last Mobile Launcher to be converted for use by the Space Shuttle. The LUT and Milkstool were dismantled and placed into storage, and the base of the launch platform was modified to accommodate the locations of engines on the shuttle. The platform was redesignated MLP-3.
In total, MLP-3 was used for 29 Shuttle launches, starting in 1990. It was the least used of the three MLPs. Following the Space Shuttle retirement, NASA kept the MLP-3 for solid-propellant rockets. [10]
Usage of MLP-3 to launch the OmegA rocket was granted to Orbital ATK (later bought out by Northrop Grumman) following discussions in 2016, [19] and later formalized through a Reimbursable Space Act Agreement in August 2019. [20] Under the Agreement, Vehicle Assembly Building High Bay 2 would be used to assemble the rocket, while MLP-3 and crawler-transporter 1 would be used to move the rocket to LC-39B for launch. From 2019 to 2020, the OmegA launch tower was under construction on MLP-3. Following the cancellation of OmegA in September 2020, work began to demolish the half-completed launch tower. [21] As of January 2021, MLP-3 is planned to be placed in storage in High Bay 2 of the Vehicle Assembly Building. [12] [13] In 2023, MLP-3 was demolished to make room in High Bay 2 for other NASA operations. [22]
Between 2009 and 2010, a mobile launcher platform called the Mobile Launcher-1 (ML-1) was constructed as part of the Constellation program. Since the cancellation of the program in 2010, ML-1 was converted for the Space Launch System Block 1, with various phases of construction between 2013 and 2018. The total cost of the ML-1 is estimated to be $1 billion. [23]
The biggest modification to the ML-1 was on the platform's base, where engineers increased the size of a 22 square feet (2.0 m2) exhaust duct to a rectangle stretching 60 by 30 feet (18.3 by 9.1 m) and strengthened the surrounding structure. SLS weighs more than twice as much as the planned Ares I rocket. The Ares I rocket would have featured a single solid-fueled first stage, while the SLS includes two large solid rocket boosters and a powerful core with four RS-25 engines. The base of the ML-1 is 25 feet (7.6 m) high, 158 feet (48 m) long, and 133 feet (41 m) wide. [24] The ML-1 also features a 355-foot-tall (108 m) Launch Umbilical Tower (LUT) with several arms that permit servicing of the SLS on the launch pad, and swing away from it at launch.
In June 2019, NASA awarded a contract for the design and construction of the Mobile Launcher-2 (ML-2) for SLS Block 1B. [24] Construction of the ML-2 began in July 2020, with the planned completion in 2023. The total cost of the ML-2 was originally estimated to be $450 million, however cost overruns have seen this increase to a projected $1.8 to $2.7 billion, and a delay until 2027 or 2029 [23] [25]
The Atlas V utilizes an MLP when launching from SLC-41. The rocket is stacked on its MLP in the 280-foot-tall (85.4 m) Vertical Integration Facility (VIF), and is then rolled-out over 600 yards (550 m) to the launch pad. [26] The design of this MLP is derived from the MLPs used by the Titan III and IV rockets.
Titan III and Titan IV rockets launched from SLC-40 and SLC-41 utilized MLPs to decouple assembly of the launch vehicle from launch. This was meant to enable simultaneous assembly of multiple launch vehicles as part of the Titan's Integrate-Transfer-Launch (ITL) concept, allowing a high flight rate from a small number of launch pads. [27]
United Launch Alliance's Vulcan will use an MLP similar in design to the one used by the Atlas V when launching from SLC-41, altered to support the former's larger design. The VLP (Vulcan Launch Platform) [28] stands 183 ft (56 m) tall, and when complete will weigh 1.3 million pounds (590 tonnes). It will be equipped with various electronics, power-lines, and cables to support and control the rocket. For the initial Vulcan-Centaur configuration, the MLP will supply liquefied natural gas and liquid oxygen to the first stage, and liquid hydrogen and liquid oxygen to the Centaur upper stage. As of October 24,2019, [update] the basic structure has been completed, but the umbilicals and equipment have yet to be installed. [29] As of 2024, there are two VLP’s allowing for parallel processing. [30]
Japanese H-IIA and H-IIB rockets utilize an MLP when launching from the Yoshinobu Launch Complex.
The PSLV, GSLV, and GSLV Mark III rockets utilize an MLP called the Mobile Launch Pedestal. [31] The rockets are stacked on the Mobile Launch Pedestal in the Vehicle Assembly Building (VAB; not to be confused with the NASA building with the same name), and are then rolled-out towards the launch pad. [32]
Once delivered to the pad, the mobile launcher platform is connected to the larger sound suppression system by large pipes which deliver a deluge of water from an adjacent water tower. Six 12-foot-high (3.7 m) towers known as "rainbirds" spray water over the MLP and into the flame deflector trenches below it, absorbing acoustic waves. The suppression system reduced the acoustic sound level to approximately 142 dB. [33]
The John F. Kennedy Space Center, located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since 1968, KSC has been NASA's primary launch center of American spaceflight, research, and technology. Launch operations for the Apollo, Skylab and Space Shuttle programs were carried out from Kennedy Space Center Launch Complex 39 and managed by KSC. Located on the east coast of Florida, KSC is adjacent to Cape Canaveral Space Force Station (CCSFS). The management of the two entities work very closely together, share resources, and operate facilities on each other's property.
The Vehicle Assembly Building, or VAB, is a large building at NASA's Kennedy Space Center (KSC) in Florida, designed to assemble large pre-manufactured space vehicle components, such as the massive Saturn V, the Space Shuttle and the Space Launch System, and stack them vertically onto one of three mobile launcher platforms used by NASA. As of March 2022, the first Space Launch System (SLS) rocket was assembled inside in preparation for the Artemis I mission, launched on November 16, 2022.
A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. The term launch pad can be used to describe just the central launch platform, or the entire complex. The entire complex will include a launch mount or launch platform to physically support the vehicle, a service structure with umbilicals, and the infrastructure required to provide propellants, cryogenic fluids, electrical power, communications, telemetry, rocket assembly, payload processing, storage facilities for propellants and gases, equipment, access roads, and drainage.
The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined command and service module (CSM) and an Apollo Lunar Module (LM). Two additional components complemented the spacecraft stack for space vehicle assembly: a spacecraft–LM adapter (SLA) designed to shield the LM from the aerodynamic stress of launch and to connect the CSM to the Saturn launch vehicle and a launch escape system (LES) to carry the crew in the command module safely away from the launch vehicle in the event of a launch emergency.
The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage, with the S-IVB. The S-IB first stage also increased the S-I baseline's thrust from 1,500,000 pounds-force (6,700,000 N) to 1,600,000 pounds-force (7,100,000 N) and propellant load by 3.1%. This increased the Saturn I's low Earth orbit payload capability from 20,000 pounds (9,100 kg) to 46,000 pounds (21,000 kg), enough for early flight tests of a half-fueled Apollo command and service module (CSM) or a fully fueled Apollo Lunar Module (LM), before the larger Saturn V needed for lunar flight was ready.
Launch Complex 39A (LC-39A) is the first of Launch Complex 39's three launch pads, located at NASA's Kennedy Space Center in Merritt Island, Florida. The pad, along with Launch Complex 39B, was first constructed in the 1960s to accommodate the Saturn V launch vehicle, and has been used to support NASA crewed space flight missions, including the historic Apollo 11 moon landing and the Space Shuttle. The site is currently leased by SpaceX and supports launches of the Falcon 9 and Falcon Heavy rockets.
The crawler-transporters, formally known as the Missile Crawler Transporter Facilities, are a pair of tracked vehicles used to transport launch vehicles from NASA's Vehicle Assembly Building (VAB) along the Crawlerway to Launch Complex 39. They were originally used to transport the Saturn IB and Saturn V rockets during the Apollo, Skylab and Apollo–Soyuz programs. They were then used to transport Space Shuttles from 1981 to 2011. The crawler-transporters carry vehicles on the mobile launcher platforms (MLPs) used by NASA, and after each launch return to the pad to take the platform back to the VAB.
A service structure is a steel framework or tower that is built on a rocket launch pad to facilitate assembly and servicing.
Launch Complex 39 (LC-39) is a rocket launch site at the John F. Kennedy Space Center on Merritt Island in Florida, United States. The site and its collection of facilities were originally built as the Apollo program's "Moonport" and later modified for the Space Shuttle program. Launch Complex 39 consists of three launch sub-complexes or "pads"—39A, 39B, and 39C—a Vehicle Assembly Building (VAB), a Crawlerway used by crawler-transporters to carry mobile launcher platforms between the VAB and the pads, Orbiter Processing Facility buildings, a Launch Control Center which contains the firing rooms, a news facility famous for the iconic countdown clock seen in television coverage and photos, and various logistical and operational support buildings.
Shuttle-derived vehicles (SDV) are space launch vehicles and spacecraft that use components, technology, and infrastructure originally developed for the Space Shuttle program.
The Crawlerway is a 130-foot-wide (40 m) double pathway at the Kennedy Space Center in Florida. It runs between the Vehicle Assembly Building and the two launch pads at Launch Complex 39. It has a length of 3.4 and 4.2 miles to Pad 39A and Pad 39B, respectively. A seven-foot (2 m) bed of stones lies beneath a layer of asphalt and a surface made of Alabama river rocks.
Launch Complex 34 (LC-34) is a deactivated launch site on Cape Canaveral Space Force Station, Florida. LC-34 and its companion LC-37 to the north were used by NASA from 1961 through 1968 to launch Saturn I and IB rockets as part of the Apollo program. It was the site of the Apollo 1 fire, which claimed the lives of astronauts Gus Grissom, Ed White, and Roger Chaffee on January 27, 1967. The first crewed Apollo launch — Apollo 7 on October 11, 1968 — was the last time LC-34 was used.
Space Launch Complex 41 (SLC-41), previously Launch Complex 41 (LC-41), is an active launch site at Cape Canaveral Space Force Station. As of 2024, the site is used by United Launch Alliance (ULA) for Atlas V and Vulcan Centaur launches. Previously, it had been used by the United States Air Force for Titan IIIC, Titan IIIE, and Titan IV launches.
Launch Complex 39B (LC-39B) is the second of Launch Complex 39's three launch pads, located at NASA's Kennedy Space Center in Merritt Island, Florida. The pad, along with Launch Complex 39A, was first designed for the Saturn V launch vehicle, which at the time was the United States' most powerful rocket. Typically used to launch NASA's crewed spaceflight missions since the late 1960s, the pad is currently configured for use by the agency's Space Launch System rocket, a Shuttle-derived launch vehicle which is currently used in the Artemis program and subsequent Moon to Mars campaigns. The pad had also been leased by NASA to aerospace company Northrop Grumman, for use as a launch site for their Shuttle-derived OmegA launch vehicle, for National Security Space Launch flights and commercial launches, before the OmegA program was cancelled.
Ares I-X was the first-stage prototype and design concept demonstrator of Ares I, a launch system for human spaceflight developed by the National Aeronautics and Space Administration (NASA). Ares I-X was successfully launched on October 28, 2009. The project cost was $445 million. It was the final launch from LC-39B until Artemis 1 13 years later.
The NASA Railroad is a Class III industrial short-line railroad at the Kennedy Space Center in Cape Canaveral, Florida. The railroad consists of 38 miles (61 km) of track connecting the mainline of the Florida East Coast Railway and trackage at the Cape Canaveral Space Force Station. NASA uses the railroad to deliver large or bulk materials to support its operations, particularly solid rocket boosters and chemicals such as helium and oxygen for rocket fuel.
The retirement of NASA's Space Shuttle fleet took place from March to July 2011. Discovery was the first of the three active Space Shuttles to be retired, completing its final mission on March 9, 2011; Endeavour did so on June 1. The final shuttle mission was completed with the landing of Atlantis on July 21, 2011, closing the 30-year Space Shuttle program.
SA-500F was a Saturn V test model used by NASA to test facilities at Launch Complex 39 at the Kennedy Space Center on Merritt Island, Florida throughout 1966. Tests included the mating of the Saturn's stages in the Vehicle Assembly Building (VAB), the fit of the service platforms, the launcher-transporter operation, the propellant loading system, and the test connections to the mobile launcher and support equipment.
OmegA was a medium-lift to heavy-lift launch vehicle concept that spent several years in development by Northrop Grumman during 2016–2020, with that development substantially funded by the U.S. government. OmegA was intended for launching U.S. national security satellites, as part of the U.S. Department of the Air Force National Security Space Launch (NSSL) replacement program.
NASA's Exploration Ground Systems (EGS) Program is one of three programs based at NASA's Kennedy Space Center in Florida. EGS was established to develop and operate the systems and facilities necessary to process and launch rockets and spacecraft during assembly, transport and launch. EGS is preparing the infrastructure to support NASA's Space Launch System (SLS) rocket and its payloads, such as the Orion spacecraft for Artemis I. Artemis I is the first to launch in a series of increasingly complex missions that will enable human exploration to the Moon and Mars.
This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration .