The Real Story Behind the Game
Apollo 13 launched on April 11, 1970, carrying Commander Jim Lovell, Command Module Pilot Jack Swigert, and Lunar Module Pilot Fred Haise toward the Moon. It was meant to be NASA’s third lunar landing. Roughly 56 hours into the flight, a routine request from Mission Control to “stir” the cryogenic oxygen tanks triggered a short circuit inside oxygen tank number two. The tank exploded, tearing open the Service Module, knocking out two of three fuel cells, and venting the crew’s oxygen into space.
Swigert radioed the now-famous words, “Okay, Houston, we’ve had a problem here,” and Lovell repeated them moments later. Note the wording: the real transmission was past tense - “we’ve had a problem.” The present-tense version most people know, “Houston, we have a problem,” comes from the 1995 film. The Moon landing was cancelled within minutes; survival was now the only mission.
Why the Free-Return Trajectory?
With the Service Module crippled, the main engine could not be trusted - it sat directly behind the damaged section and might have been wrecked in the blast. A “direct abort” that turned the spacecraft straight around would have required firing that engine and burning propellant the crew no longer had. Instead, flight controllers chose the free-return trajectory: a path that loops around the far side of the Moon and uses lunar gravity to sling the spacecraft back toward Earth, requiring only small correction burns.
The crew powered down the Command Module to preserve its batteries for re-entry and moved into the Lunar Module, using it as a lifeboat it was never designed to be. One of the trajectory-correction burns - the “PC+2” burn - had to be flown manually, without the guidance computer. With no automatic alignment, Lovell kept the Earth centered in the spacecraft window as a visual reference while Haise and Swigert called out the timing - the same nerve-wracking task you fly in the game.
The Long, Cold Way Home
The return trip was brutal. Power was rationed so severely that cabin temperatures dropped near freezing and water condensed on the walls. Drinking water was cut to a few ounces a day. Carbon dioxide built up to dangerous levels because the Lunar Module’s round scrubber canisters could not fit the Command Module’s square ones - so engineers on the ground invented a fix from a plastic bag, cardboard, a suit hose, a sock, and duct tape, and talked the crew through building it. That improvised “mailbox” is one of the great moments of practical engineering under pressure, and it is the scrubber puzzle you assemble in the game.
On April 17, 1970, after nearly four days of cold, thirst, and uncertainty, the crew jettisoned the Service Module - photographing the gaping hole where the panel had blown off - climbed back into the Command Module, held the correct attitude through a blistering re-entry, survived the communications blackout, and deployed their parachutes for a safe splashdown in the Pacific Ocean. NASA called it a “successful failure”: the landing was lost, but three lives were saved through teamwork, improvisation, and steady nerves.
How to Play
Pick a difficulty - Cadet for a relaxed run, Test Pilot for a true white-knuckle rescue - then launch. After the explosion, choose the free-return trajectory, power the spacecraft down fast to save the batteries, and fly the manual burn by keeping Earth in the crosshairs. On the coast home you will ration oxygen, power, and water while answering the same hard tradeoffs the real crew faced, then build the CO₂ scrubber and fly re-entry. Every choice feeds your final mission grade, so chase a perfect “S - Flawless Flight” and beat your best score.
Keep Exploring
Love space and the night sky? Explore the rest of Solar Ruler: track the Moon phase tonight, watch live solar weather and the Kp index, see what is up after dark on the Tonight’s Sky page, or follow upcoming eclipses. The same Sun that powers the aurora is the star Apollo 13 flew beneath on its way to the Moon.