The question of how fast a spacecraft travels to the Moon involves the high velocities required for deep space exploration. Sending a crewed vehicle on a quarter-million-mile journey requires significant energy and speed, far beyond what is needed for Earth orbit. The actual speed achieved by lunar missions—such as the historic Apollo program and the planned Artemis missions—is a fleeting peak necessary to overcome Earth’s powerful gravitational pull. Understanding this maximum velocity and the subsequent dynamics of the journey clarifies why reaching the Moon is a complicated feat of celestial mechanics.
The Critical Correction: Why Shuttles Didn’t Go to the Moon
The Space Shuttle was a marvel of engineering, but it was designed specifically for operations in Low Earth Orbit (LEO) and never possessed the capability to travel to the Moon. Its primary role was ferrying crew and cargo, such as satellites and components for the International Space Station, to altitudes typically between 185 and 400 miles above Earth. To maintain orbit at these lower altitudes, the Space Shuttle traveled at an approximate speed of 17,500 miles per hour (28,000 kilometers per hour).
This orbital velocity is substantial, but it is not enough to break free from Earth’s gravitational influence and head toward the Moon. The vehicle’s propulsion system was designed only for orbital maneuvers and de-orbit burns, not for the thrust required for a lunar trajectory. The Shuttle’s Orbital Maneuvering System (OMS) engines did not carry the vast quantities of propellant necessary for the Trans-Lunar Injection (TLI) burn.
A spacecraft returning from the Moon hits Earth’s atmosphere at speeds much higher than those experienced by a returning Shuttle orbiter. The Space Shuttle was protected by a heat shield optimized only for LEO re-entry speeds. A lunar return would have required a much more robust, ablative heat shield to withstand the extreme thermal loads. Vehicles that successfully carried humans to the Moon, like the Apollo spacecraft, were launched on the Saturn V rocket, a system engineered specifically for deep space travel.
Speed Required to Escape Earth’s Gravity
To reach the Moon, a spacecraft must first achieve a speed that allows it to escape the Earth’s dominant gravitational field. This threshold, known as escape velocity, is approximately 25,000 miles per hour (40,200 kilometers per hour) at the Earth’s surface. A lunar mission does not need to reach this exact figure, however, because the Moon’s own gravity will eventually take over and pull the spacecraft in.
The maneuver that sends a spacecraft out of Earth orbit and onto a path toward the Moon is called Trans-Lunar Injection (TLI). This burn occurs after the spacecraft has achieved a stable parking orbit around Earth. The TLI burn is performed by a powerful final stage of the launch vehicle, such as the Saturn V’s S-IVB stage during the Apollo program.
During the TLI, the rocket engine reignites for several minutes, providing a boost in velocity. For the Apollo missions, the spacecraft was traveling at its LEO speed of around 17,500 miles per hour before the burn. The TLI added approximately 6,800 to 7,200 miles per hour (3.05 to 3.25 kilometers per second) to the vehicle’s trajectory.
This acceleration resulted in the spacecraft reaching its highest speed relative to Earth, a peak velocity of approximately 24,250 miles per hour (39,000 kilometers per hour). For Apollo 11, the recorded maximum outbound velocity was 35,570 feet per second after the TLI burn. This velocity was slightly less than the theoretical escape velocity, but it was enough to stretch the orbit into an elongated ellipse that would intersect with the Moon’s path.
The Journey’s Average Velocity and Time
Immediately after the TLI burn concludes, the spacecraft is no longer actively accelerating and begins a passive coast phase. Earth’s gravity immediately starts to slow the vehicle down, much like a ball thrown into the air. The spacecraft is essentially climbing out of Earth’s gravitational well, trading its kinetic energy for gravitational potential energy.
As the distance from Earth increases, the vehicle’s speed steadily drops. It reaches its minimum speed at the point where the gravitational pull of the Earth and the Moon are nearly equal. After passing this point, the spacecraft begins to accelerate again as it falls toward the Moon, which is now the dominant gravitational influence.
The journey is not a constant-speed cruise, but a continuous cycle of deceleration and then acceleration. The average velocity over the entire journey is much lower than the peak TLI speed. The Apollo missions, for example, typically took about three days, or roughly 70 to 76 hours, to travel from Earth orbit to lunar orbit insertion.
The total travel time can vary depending on the specific trajectory and the relative positions of the Earth and the Moon. The Artemis I uncrewed mission, which used a more distant orbit around the Moon, took about five days to reach lunar orbit. The journey to the Moon remains a multi-day commitment due to the vast distance and the non-linear speed profile dictated by gravitational forces.