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Rockets: engines, stages and the capacity to reach space

A rocket is defined by more than its power. Its architecture, engines, and the orbit or mission it is designed for determine what it can carry and how far it can go. The documentation available here describes several vehicles—the NASA Space Launch System (SLS), New Glenn and Ariane 6—and some of their propulsion systems. It also shows why a payload figure must always be understood in relation to its destination.

By CosmoInsider editorial team Published 5 min
Rockets: engines, stages and the capacity to reach space
Type: Image · real photograph Provider: Openverse Author: Ariane Group Credit: "André-Hubert Roussel devant une fusée Ariane 6" by Ariane Group is licensed under CC BY-SA 4.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/4.0/. Licence: CC BY-SA 4.0 Colour treatment: original

Key facts

  • NASA links SLS to Artemis and says the RL10 provided in-space propulsion for uncrewed Orion during Artemis I.
  • NASA says the SLS ICPS uses an RL10 burning liquid hydrogen and oxygen and producing 24,750 pounds of thrust.
  • The SLS core stage is 212 feet tall and 27.6 feet in diameter and feeds four RS-25 engines.
  • NASA attributes seven BE-4 engines to New Glenn and capacity of more than 13 metric tons to geostationary transfer orbit and 45 to low Earth orbit.
  • ESA describes Ariane 6’s main stage as 32 meters tall and 5.4 meters wide, powered by a Vulcain 2.1 engine.

Related records

What is being compared when we talk about rockets

A launch vehicle is the system that carries a payload from Earth into space. The sources describe vehicles with different configurations and purposes: SLS is linked to NASA’s Artemis lunar missions; New Glenn appears in NASA’s launch services program; and Ariane 6 is described through the features of its stages and engines. Their capacity figures therefore should not be treated as entries in a single, straightforward ranking.

Capacity depends, among other things, on the payload’s destination. NASA says New Glenn can carry more than 13 metric tons to geostationary transfer orbit and 45 metric tons to low Earth orbit. These are figures for different destinations. They do not mean the rocket carries both payloads on the same mission, and they do not allow a direct comparison with SLS or Ariane 6 without equivalent data.

Stages are sections of a launch vehicle that perform different functions during flight. The sources identify a core stage for SLS and a main, or core, stage for Ariane 6. They also describe side-mounted solid rocket boosters on SLS and solid motors on Ariane 5. The Ariane 5 information comes from a technical data sheet hosted by NASA, rather than a current mission-description page.

SLS: a system designed for Artemis missions

The Space Launch System, or SLS, is NASA’s deep-space exploration rocket. The agency connects it with Artemis, its program of crewed and uncrewed lunar missions. According to NASA’s fact sheet, Artemis I used an uncrewed Orion spacecraft: the RL10 engine provided in-space propulsion to send it toward the Moon. NASA says the engine is set to reprise that role on Artemis II and Artemis III, which it describes as crewed lunar missions.

The RL10’s role in this account is in-space propulsion, not every engine that powers the rocket from the launch pad. NASA says SLS’s Interim Cryogenic Propulsion Stage (ICPS) uses an RL10 made by L3Harris. The engine burns liquid hydrogen and liquid oxygen and produces 24,750 pounds of thrust. The source does not provide a comparison with other engines here, so the figure should be read as a specification for this component, not as the total thrust of SLS.

NASA says the SLS core stage is 212 feet tall and 27.6 feet in diameter. It stores cryogenic liquid hydrogen and oxygen and contains the systems that feed them to four RS-25 engines. It also houses the flight computers and much of the avionics. NASA has also announced the completed assembly of RS-25 Engine 2063 for the SLS family; the available description says RS-25 engines power the core stage.

Solid boosters and liquid engines

SLS combines different kinds of propulsion systems. NASA describes its solid rocket boosters as the largest and most powerful solid-propellant boosters built for flight. Each stands 17 stories tall and burns approximately six tons of propellant every second. According to the agency, each booster produces more thrust than 14 four-engine aircraft. That comparison conveys the scale NASA attributes to the component, but it is not a substitute for a thrust figure expressed in common units for comparing rockets.

For Ariane 6, the European Space Agency (ESA) describes the main stage, located at the vehicle’s base. It is 32 meters tall and 5.4 meters wide, with a mass of 23,000 kilograms without propellant. It is powered by the Vulcain 2.1, which burns liquid oxygen. The information cited here does not give Ariane 6’s overall performance or specify every possible configuration, so these dimensions and the engine describe a major part of the rocket, not a complete capacity specification.

A technical sheet for Ariane 5 hosted by NASA describes a different architecture: two segmented solid motors at liftoff, each producing more than 500 tonnes of thrust, alongside a core stage powered by a Vulcain engine using liquid oxygen and hydrogen. The sheet summarizes the vehicle as a 2.5-stage system with four propulsion units. Ariane 5 and Ariane 6 are different vehicles; specifications for one should not be transferred to the other.

New Glenn and why destination matters

NASA says New Glenn is powered by seven Blue Engine 4 (BE-4) engines. In its launch services program information, the agency gives its capacity as more than 13 metric tons to geostationary transfer orbit and 45 metric tons to low Earth orbit. A transfer orbit is a trajectory used on the way to another orbit; low Earth orbit is closer to Earth. The key point is that the amount a rocket can carry changes with its destination.

The same page says New Glenn is included in NASA’s Launch Services II contract. This places the vehicle within an agency launch-services framework, but the evidence provided does not detail a flight schedule, specific contracted missions or operational results. Nor does the excerpt give the characteristics of each of the seven engines or explain how work is divided among stages.

What the data establish—and what remains unknown

Taken together, the sources show several ways of building launch capability: liquid engines in core stages, engines for propulsion in space, and solid boosters that add thrust during liftoff. They also make clear that “power” alone cannot describe a rocket. Payload capacity depends on destination, and the specification for one engine or stage is not the performance of the entire vehicle.

  • SLS: linked to Artemis; its documentation describes a core stage with four RS-25 engines, an ICPS with one RL10, and solid boosters.
  • New Glenn: NASA reports seven BE-4 engines and different capacity figures for geostationary transfer orbit and low Earth orbit.
  • Ariane 6: ESA details the dimensions of its main stage and its Vulcain 2.1 engine.
  • Ariane 5: the cited technical sheet describes a different configuration, with solid motors and a Vulcain core stage.

The evidence does not provide consistent data on total mass, cost, launch rate, flight history or capacity to the same destinations for every vehicle. It can explain components and some stated capabilities, but it cannot establish which rocket is “best” or support a comprehensive comparison.