Aerospike Engines: Their Past, Present, and Future

What is an Aerospike Engine?

An aerospike engine is a type of rocket engine that maintains its efficiency at a wide range of altitudes, primarily due to its unique design.

The central feature of the aerospike design is its altitude-compensating exhaust nozzle. This nozzle essentially inverts the traditional bell-shaped design found in most rocket engines. Instead of a bell, an aerospike engine features a radial exhaust, which extends outward like the spokes on a wheel. The “spike” in the middle of the engine can be either a solid structure or just a shape formed by the arrangement of the rocket’s exhaust nozzles.

Source: NASA


The benefits of an aerospike engine include:

Altitude Compensation: The traditional bell nozzle of a rocket engine works best at one specific ambient pressure, meaning its performance will be optimal at one specific altitude. Aerospike engines, on the other hand, have exhaust gases that expand along an outwardly flared spike, which automatically adjusts to changing ambient pressure. This results in nearly optimal performance at all altitudes.

Efficiency: The aerospike design allows for a greater overall efficiency compared to traditional rocket engine designs. This increased efficiency could lead to a significant reduction in the amount of fuel required for space missions.

Past and Present

The concept of the aerospike engine has been around since the 1960s. Rocketdyne, a prominent rocket engine manufacturer, initiated development of this engine type around that time. The project, however, was abandoned due to budget constraints and the complexity of the technology. The concept was later revived by NASA in the late 1990s with the X-33/VentureStar project, which aimed to produce a reusable launch vehicle. This project also eventually fell through due to technical and financial difficulties.

In the 2010s and 2020s, several private space companies have shown interest in aerospike technology. The development of aerospike engines is ongoing, with a handful of companies, including Pangea Aerospace, Stoke Space, and ARCA, announcing plans to incorporate the technology in their rockets.


The most promising applications for aerospike engines are in the space industry, particularly for launching payloads into orbit. The engine’s high efficiency could make space travel more cost-effective by reducing the amount of fuel needed for each launch. This could be particularly beneficial for satellite launches, interplanetary missions, and even potential manned space exploration missions. Additionally, the aerospike engine’s altitude-compensating design could potentially be used to develop single-stage-to-orbit (SSTO) vehicles, which could revolutionize the economics of space travel.

Currently, no aerospike engine has been used for an operational orbital launch.

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