How long does it take astronauts to reach the Moon?

The journey to the Moon isn't a powered trip but a push followed by a long fall. Apollo 11 launched on 16 July 1969, fired the Saturn V's third stage less than three hours later to leave Earth orbit, and spent the next two and a half days coasting. The engine fired again to brake and enter lunar orbit, and the Eagle lunar module touched down in the Sea of Tranquility 102 hours and 45 minutes after launch — just over four days by the clock.

The trip could be shortened, but it comes at a cost. A faster trajectory requires more propellant at departure and, above all, far more to brake on arrival: without braking, the spacecraft simply flies past. The Apollo missions' roughly three days were the balance point between fuel consumption, safety margin, and the ability to return via a free-return trajectory if something went wrong, as happened on Apollo 13.

Without a crew on board, the calculations change. The New Horizons probe, launched in 2006 with the highest departure speed ever given to a spacecraft, crossed the Moon's orbit in under nine hours, though it had no intention of stopping there. At the other extreme, several recent missions have taken weeks or months using low-energy trajectories that build up speed through successive loops around Earth. Travel time doesn't measure distance: it measures how much energy you're willing to spend. The next crewed flights won't be any faster either, and will keep the same order of magnitude as Apollo for the outbound trip.