FLOWN APOLLO 13 AQUARIUS DESCENT ENGINE SCHEMATIC.
THE ROCKET ENGINE THAT SAVED THE CREW.
"SCS Overview, 3 SCS," (Stabilization and Control System) schematic drawing from the Apollo 13 LM Systems Data Book. Single folded sheet, 36½ x 10½ inches, with a "SCS Overview" tab.
This schematic is the one single flown sheet from Apollo 13 containing precise engineering information on the rocket engine that saved the crewthe Descent Propulsion Section (DPS). The DPS main component was the large rocket engine located in the center of the Lunar Module's Descent Stage. This schematic illustrates the complex system of electronics and other equipment that comprised the "stabilization and control" that permitted the crew's operation of this rocket engine.
Engine "burns" from this system allowed the crew to return back to the "free-return" trajectory, the "PC+2" burn two hours after the closest approach to the moon to allow a quicker return to the earth, and the MCC-5 or Mid Course Correction number 5 burn to set up the proper angles for the Command Module and crew to enter the Earth's atmosphere.
An included letter of provenance by FRED HAISE reads in part: "Accompanying this letter is a folded sheet labeled 3 SCS from the Apollo 13 LM Systems Data Book carried on the flight of Apollo 13 during April 11 to 17, 1970....
This particular schematic illustrates the Stabilization and Control System Overview for the LM Descent Engine and shows multiple control panel knobs and switches including 'START,' 'ABORT,' 'ABORT STAGE,' 'LUNAR CONTACT,' and a dual indicator meter for engine 'THRUST' levels. All of these have their corresponding electrical lines. A drawing of the Data Entry and Display Assembly or 'DEDA' is shown with the corresponding signal flow. Also, there is a diagram of the LM Reaction Control System's 16 thruster engines and its association with the SCS.
Many of our LM systems were powered down during the period after the explosion to conserve electrical power. It was reassuring to have this and other schematics in the Data Book as a trouble shooting tool in case of any other failures during the remaining of the flight....
I have inscribed and signed the schematic with: 'Carried to the moon on Apollo 13, Fred Haise, Apollo 13 LMP' near the center of the sheet."
Additionally SIGNED AND INSCRIBED near the upper right corner with: "James Lovell, Apollo 13 CDR."