Amodular rocket is a kind ofmultistage rocket which has components that can interchanged for different missions. Several such rockets use similar concepts such as unified modules to minimize expenses on manufacturing, transportation and for optimization of support infrastructure for flight preparations.
TheNational Launch System study (1991-1992) looked at future launchers in a modular (cluster) fashion. This concept has existed since thecreation of NASA.
A government commission, the "Saturn Vehicle Evaluation Committee" (better known as theSilverstein Committee), assembled in 1959 to recommend specific directions that NASA could take with the existing Army rocket program (Jupiter, Redstone, Sergeant). NASA's Space Exploration Program Council (1959-1963) was tasked with developing the launch architecture for the newSaturn rocket series, called Saturn C.The Saturn C architecture consisted of five different stages (S-I,S-II,S-III,S-IV, and S-V/Centaur) that could be stacked vertically for specific rockets to meet various NASA payload and mission requirements.
This work led to development of theSaturn I,Saturn IB, andSaturn V rockets.
TheAtlas Vexpendable launch system uses theliquid fueledCommon Core Booster as its first stage. In many configurations, a single CCB is used with strap-onsolid rocket boosters. A proposed configuration for heavier loads strapped together three CCBs for the first stage. The Common Core Booster utilizes the Russian madeRD-180 burningRP-1 fuel withliquid oxygen producing a thrust of 3.8MN. The liquid propellant tanks use anisogrid design for strength, replacing previous Atlas tank designs which were pressure stabilized.[1]
The length of the common core booster is 89 feet (27 m), and has a diameter of 12.5 feet (3.8 m).[2]
TheDelta IV launcher family used the liquid fuelCommon Booster Core as the first stage of the various rocket configurations. One or three modules could be used as the first stage. In most configurations a single CBC is used with or without strap-on SRBs. Three CBCs together formed the first stage of the Heavy configuration. The CBC used theRocketdyneRS-68 engine and burnedliquid hydrogen with liquid oxygen producing a thrust of 2.9 meganewtons (650,000 lbf).[citation needed]
TheUniversal Rocket Module (URM) is the modularliquid fueled first stage of the Angaraexpendable launch system. Depending on the configuration, the first stage can consist of 1, 3, 5 or 8 URMs. Each URM uses a Russian-madeRD-191 engine burningRP-1 fuel withliquid oxygen producing a thrust of 1.92MN.[3]
The Falcon Heavy launch vehicle consists of a strengthenedFalcon 9 Block 5 center core with two regular Falcon 9 Block 5 core stages with aerodynamic nosecones mounted on top of both acting as liquid-fuel strap-on boosters. Each core is powered by nineMerlin 1D engines burningrocket-grade kerosene fuel withliquid oxygen producing almost 7.7 meganewtons (1,700,000 lbf) of thrust, and all three cores together producing over 22 MN of thrust. A first design of the Falcon Heavy included a unique propellant crossfeed capability, where fuel and oxidizer to power most of the engines on the center core would be fed from the two side cores, up until the side cores would be near empty and ready for the firstseparation event.[4] However, due to its extreme complexity this feature was cancelled in 2015 leaving each of the three cores to burn its own fuel. Later evaluations revealed that the propellant needed for each side booster to land (reuse) are already close to the margins so there is really no advantage to crossfeed.
Like the single stick Falcon 9, each Falcon Heavy booster core isreusable.[5] TheFalcon Heavy Test Flight demonstrated the two side boosters landing simultaneously near their launch site, while the central booster attempted a landing on SpaceX'sAutonomous spaceport drone ship, which resulted in a hard landing near the ship. During the second mission all three boosters landed softly.[6] A Falcon Heavy launch that succeeds in recovering all three core boosters has the same material expenditure as the Falcon 9, i.e. the upper stage and potentially thepayload fairing. As such, the difference in cost between a Falcon 9 and a Falcon Heavy launch is limited, mainly to the extra fuel and refurbishing three as opposed to one booster core.