SpaceX Completes Crucial Starship Engine Tests for NASA’s Lunar Landing

In a significant stride towards NASA’s Artemis Program, SpaceX has achieved a critical milestone, said NASA on Sept. 14, by successfully concluding a series of pivotal Raptor Engine tests for the Starship Human Landing System (HLS), scheduled for use during the Artemis III and Artemis IV Missions.

Test of a Raptor Vacuum Engine chilled to mimic conditions after a long coast period in space. Credits: SpaceX

These Missions represent a historic endeavor to land American Astronauts near the Lunar South Pole, heralding a momentous return to the Moon after more than half-century, and opening the door to future Lunar Exploration.

Raptors: Starship’s Pusher

The linchpin of the Starship HLS is its propulsion system, which relies on two distinct versions of SpaceX’s groundbreaking Raptor Engines.

Starship's 33 Raptor Engines plume as seen from the launch and Catch Tower. Credits: SpaceX — *Starship’s 33 Raptor Engines plume as seen from the launch and Catch Tower during the first Integrated Flight Test. Credits: SpaceX*

One is fine-tuned for optimal performance within Earth’s atmospheric conditions, specifically known as “sea-level Raptor”. The other variant is purpose-built to operate seamlessly in the vacuum of space, where the absence of an atmosphere presents unique engineering challenges.

This dual-engine configuration is pivotal for ensuring the spacecraft’s adaptability to the vastly different environments it will encounter during its Mission.

The Pivotal Test

A recent feat in this collaborative endeavor was the successful validation of one of the vacuum-optimized Raptor engine’s functionalities.

This crucial test confirmed the engine’s ability to initiate and operate under the extreme cold conditions encountered during extended space missions. A notable distinction of Artemis missions from those in Low Earth Orbit is the potential for the landers to endure extended periods of inactivity in space, subjecting the hardware to temperatures far lower than those experienced in shorter missions closer to Earth.

Test of a Raptor Vacuum engine chilled to mimic conditions after a long coast period in space pic.twitter.com/o3kGEf9UtI
— SpaceX (@SpaceX) September 14, 2023

One of the earliest milestones achieved under SpaceX’s Artemis III contract, dating back to November 2021, was an engine test that carried immense significance says NASA.

During this 281-second-long test firing, the Raptor engine showcased its prowess by executing a pivotal phase of the Lunar Landing procedure known as the powered descent. This phase marks the moment when the Starship HLS departs from its lunar orbit and initiates its descent towards the Moon’s surface for a precise landing.

*The 281-second throttle Test demonstrated the Starship Raptor engine’s ability to meet the demands of a descent burn to the Lunar surface. Credit: SpaceX*

The test served a dual purpose. Firstly, it demonstrated the Raptor engine’s capacity to modulate its power output dynamically over time — a critical feature referred to as “the throttle profile”. Secondly, it substantiated the engine’s capability to sustain stable operation for the entire duration of the powered descent phase.

The favorable outcome of this test filled NASA with early confidence in SpaceX’s Engine development endeavors.

Hardware-Rich Testing

Conducting rigorous testing of essential technologies and hardware under both simulated and real flight conditions constitutes a fundamental aspect of the Artemis Moon Lander’s development, and reflects the SpaceX’s Footprint of “Hardware-Rich Testing”.

These tests not only offer invaluable insights but also provide Mission-like validation of the systems indispensable for the safe transfer of astronauts to and from the lunar surface. Subsequent reviews of data stemming from these tests continue to push NASA’s assurance in the readiness of the U.S. aerospace industry to embark on this ambitious mission.

Rendering of SpaceX Starship human landing system design.Credits: SpaceX — *Rendering of SpaceX Starship human landing system design. Credits: SpaceX*

The next milestone in SpaceX’s journey towards lunar exploration encompasses the comprehensive testing of their Raptor engines during the company’s second Integrated Flight Test of the Starship and Super Heavy launch vehicle, coming up in the next few weeks, according to Kathy Lueders, SpaceX’s Starbase General Manager.

As this collaboration between NASA and SpaceX advances, everyone should remember that the day when a Human Being will once more set foot on the Lunar surface is still far away in the future. But, when this will happen, will be an achievement unlocked thanks to cutting-edge technology, public-private industry collaboration and unwavering determination driving the Artemis program forward.