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Next-generation rockets: engines, stages and capabilities under scrutiny

A rocket is not defined only by its height or an engine name. Its performance results from a complete architecture: core stage, engines, boosters, upper stages and the orbit targeted by the payload. NASA and ESA documentation on SLS, Ariane 6 and New Glenn shows different ways of solving that same problem.

By CosmoInsider editorial team Published 4 min
Next-generation rockets: engines, stages and capabilities under scrutiny
Type: Image · real photograph Provider: Smithsonian Open Access Author: Abraham Bosse, French, 1602–1676 Credit: Scene from Desmarets de Saint-Sorlin's Play "Ariane" · Abraham Bosse, French, 1602–1676 · Smithsonian Institution · CC0 Licence: CC0 1.0 Colour treatment: original

Key facts

  • Every SLS configuration uses four RS-25 engines in its core stage.
  • SLS Block 1 can send more than 27 metric tons to orbits beyond the Moon.
  • Ariane 6’s core stage is 32 m tall and powered by Vulcain 2.1; P120C boosters add liftoff thrust.
  • NASA assigns New Glenn seven BE-4 engines, more than 13 metric tons to geostationary transfer orbit and 45 metric tons to low Earth orbit.

Related records

Launch vehicles turn energy stored in propellants into the speed needed to place a spacecraft or payload on a specific trajectory. This cannot be compared simply across vehicles: a payload-mass figure is meaningful only alongside its orbital destination, and an engine must be considered within the stage and configuration in which it operates. The official sources assembled here describe three cases: NASA’s Space Launch System (SLS), the European Space Agency’s Ariane 6, and New Glenn, listed by NASA under its Launch Services II contract.

An architecture, not a single engine

A launch vehicle generally divides its work among several elements. The core stage provides much of the initial thrust and carries propellants; side boosters can increase thrust at liftoff; and an upper stage may continue acceleration or carry out later maneuvers. The specific combination determines which payloads can be sent and to what destinations.

The propellant distinction also matters. NASA identifies SLS boosters as solid-propellant units. For Ariane 6, ESA says the Vulcain 2.1 core-stage engine burns liquid oxygen; the supplied description does not state the other propellant component. It would therefore be inappropriate to fill in that information with external data. In the cited NASA historical sheet for Ariane 5, by contrast, the Vulcain core engine is associated with LOX/LH2, liquid oxygen and liquid hydrogen.

SLS: four RS-25 engines and large solid boosters

SLS is NASA’s deep-space exploration rocket. Every configuration uses a core stage with four RS-25 engines. NASA says those engines, formerly known as space shuttle main engines, will power the core stage on every SLS mission. The agency also reports that the core stage is more than 200 feet tall and 27.6 feet in diameter, and stores cryogenic liquid hydrogen.

The vehicle supplements that propulsion with two solid boosters. NASA says each stands 17 stories tall and burns about six tons of propellant every second. The agency calls them the largest and most powerful solid-propellant boosters ever built for flight. These features describe the challenge of initial ascent: generating major thrust from the pad before the rocket continues its trajectory.

According to NASA, the Block 1 configuration can send more than 27 metric tons to orbits beyond the Moon. The destination matters: this is not equivalent to a low-Earth-orbit capability. In the Artemis program, the RL10 engine provided in-space propulsion to send an uncrewed Orion spacecraft to the Moon on Artemis I; NASA says it is intended to reprise that role on the crewed lunar Artemis II and III missions. The supplied material does not specify the exact SLS stage on which that engine is installed.

Ariane 6 and European technological continuity

Ariane 6 represents another combination. ESA describes a core stage 32 metres tall, 5.4 metres wide and weighing 23,000 kilograms without propellants. It is powered by a Vulcain 2.1, an upgraded development of Ariane 5’s Vulcain 2. P120C boosters add thrust at liftoff.

This continuity places the engine within a technical lineage, but does not make the two rockets identical. NASA’s Ariane 5 material describes 2.5 stages and four propulsion units. It also says that, at liftoff, its two segmented solid motors each supplied more than 500 tonnes of thrust to augment the Vulcain core engine. Those are Ariane 5 data, not specifications that can automatically be transferred to Ariane 6.

New Glenn: seven BE-4 engines and two reference destinations

NASA describes New Glenn as powered by seven Blue Engine 4, or BE-4, engines. The agency gives the vehicle a capability of more than 13 metric tons to geostationary transfer orbit and 45 metric tons to low Earth orbit. New Glenn is included in NASA’s Launch Services II contract.

The two figures show why destination changes the meaning of a specification. Low Earth orbit is relatively close to Earth compared with a geostationary-transfer trajectory, which requires a different-energy mission. For that reason, 45 and more than 13 metric tons are not competing figures: they refer to different orbital goals.

How to read these comparisons

The available information shows three documented priorities: SLS is associated with lunar exploration missions and payloads beyond the Moon; Ariane 6 combines a Vulcain 2.1 core stage with P120C boosters; and New Glenn is presented with seven BE-4 engines and published capabilities for two orbits. None of these descriptions alone establishes which is the “best” rocket. Such a conclusion would require defined criteria—cost, launch rate, reliability, reusability, mass to the same destination or operating schedule—that are absent from the supplied evidence.