17 April 1970: Apollo 13 splashed down in the Pacific Ocean at S. 21°38’24”, W. 165°21’42”, southwest of American Samoa. The landing was just 4 miles from the recovery ship, USS Iwo Jima (LPH-2).
With their spacecraft crippled by an internal explosion on 13 April, the planned lunar landing mission had to be aborted. Astronauts James A. Lovell, Jr., John L. Swigert, Fred W. Haise, Jr., worked continuously with engineers at Mission Control, Houston, Texas, to overcome a series of crises that threatened their lives.
17 April 1970: Because of the unusual configuration of the Apollo 13 Command Module, Service Module and Lunar Module “stack” during the coast from the Moon back to Earth, an additional, unplanned, Mid-Course Correction burn, MCC-7, had to be carried out. The damage to the Service Module prevented the use of its 21,900 pounds thrust (97.42 kilonewtons) Aerojet General Service Propulsion System engine. It was necessary to use the LM’s Bell Aerosystems Ascent Propulsion System engine. The APS engine produced 3,500 pounds of thrust (15.57 kilonewtons). The maneuver had to be carried out manually by the astronauts from the LM’s cockpit.
Mission Commander Lovell visually aligned the spacecraft with the LM’s Reaction Control System thrusters, by sighting the Earth in his window of the LM. Once aligned, LM pilot Fred Haise conducted the burn, which was timed by CM pilot Jack Swigert.
Swigert timed the burn using his NASA-issued Omega Speedmaster Professional Chronograph, a very accurate manual wristwatch.
The Mid Course Correction ignition commenced at T+137:39:51.5 and the engine was cutoff at T+137:40:13.0 (12:52:51–12:53.13 UTC), for a duration of 21.5 seconds.
MCC-7 was performed at EI-5 hours (137:39 GET). The same manual piloting technique used for MCC-5 was used for control during MCC-7. This was manual crew pitch and roll control with the TTCA and automatic yaw control by the AGS. MCC-7 was performed with LM RCS using the +X translation push button. It steepened the flight path angle at EI to -6.49 degrees. After MCC-7, the crew maneuvered the spacecraft to the SM separation attitude. The CM re-entry RCS system was activated and a firing test of the thrusters was successful.
—“Apollo 13 Guidance, Navigation, and Control Challenges” by John L. Goodman, United Space Alliance. American Institute of Astronautics AIAA 2009-6455 at Page 23.
The Omega Speedmaster Professional Chronograph is a manual-winding analog wrist watch produced by Omega, a luxury brand of Société Suisse pour l’Industrie Horlogère, (SSIH) and now a part of the SWATCH Group. The case is made of stainless steel and has a diameter of 48 millimeters (1.89 inches). The Speedmaster Professional, which is also known as the “Moon Watch,” or “Speedy” to watch collectors, features a stop watch function and three sub dials for recording hours, minutes and seconds. The chronograph has a black dial with tritium-painted hands and hour marks. The bezel has a tachymeter for calculating speed based on time. When fully wound, the Speedmaster can run for up to 48 hours. The chronograph is water resistant to a depth of 50 meters (164 feet).
The Speedmaster’s crystal is not glass, but “hesalite,” a clear, scratch-resistant plastic. There had been concern that if a crystal broke during a space flight, glass fragments could be scattered throughout the weightless environment of the spacecraft, presenting a danger to the astronauts.
NASA provided Omega Speedmaster Professional Chronographs to Gemini and Apollo Program astronauts. Each watch was engraved with NASA’s two-digit serial number, and could be equipped with an adjustable length Velcro strap which allowed the watch to be worn on the outside of the space suit. NASA also assigned an equipment part number.
Jack Swigert’s watch, p/n SEB12100039-002, was NASA’s number 69. It is in the collection of the Smithsonian Institution National Air and Space Museum, as Catalog Number 1977-1181.000. In 2016, the watch was on display at the University of Colorado.
15 April 1970, 01:09:40 UTC: T plus 077:56:40.0: The Apollo 13 Saturn S-IVB-508 third stage impacted the surface of The Moon north of Mare Cognitum. (S. 2° 33′ 00″, W. 27° 52′ 48″)The S-IVB hit the lunar surface at a velocity of 2.58 kilometers per second (5,771 miles per hour). The impact energy was 4.63 x 1017 ergs (1.04 kiloton).
The impact was detected by seismometers placed on the Moon by Apollo 12 astronauts Pete Conrad and Alan Bean. This was part of the Apollo Lunar Surface Experiments Package, or ALSEP.
The Apollo 12 seismometer was located 135 kilometers (83.9 miles) from the Apollo 13 third stage impact. The signals were used to calibrate the instrument package, which was in service from 1969 to 1977.
The Saturn V third stage was designated Saturn S-IVB. It was built by Douglas Aircraft Company at Huntington Beach, California. The S-IVB was 58 feet, 7 inches (17.86 meters) tall with a diameter of 21 feet, 8 inches (6.604 meters). It had a dry weight of 23,000 pounds (10,000 kilograms) and fully fueled weighed 262,000 pounds (118,841 kilograms). The third stage had one Rocketdyne J-2 engine which used liquid hydrogen and liquid oxygen for propellant. Itproduced 232,250 pounds of thrust (1,033.10 kilonewtons). The S-IVB would place the Command and Service Module into Low Earth Orbit, then, when all was ready, the J-2 would be restarted for the Trans Lunar Injection.
13 April 1970: At 10:07:53 p.m. Eastern Standard Time (mission elapsed time 55:54:53), while Apollo 13 and its crew, James A. Lovell, Jr., John L. Swigert and Fred W. Haise, were approximately 200,000 miles (322,000 kilometers) from Earth enroute to a landing at the Fra Mauro Highlands on The Moon, an internal explosion destroyed the Number 2 oxygen tank¹ in the spacecraft’s Service Module. The Number 1 tank was also damaged. Two of three fuel cells that supplied electrical power to the spacecraft failed.
Jack Swigert radioed Mission Control: “I believe we’ve had a problem here.” ²
Mission Control: “This is Houston. Say again, please.”
Jim Lovell: “Houston, we’ve had a problem. Main B Bus undervolt.”
With oxygen supplies depleted and power failing, the lunar landing mission had to be aborted, and the three-man crew evacuated the Command Module and took shelter in the Lunar Module.
This was a life-threatening event.
The story of Apollo 13 and its crew and their journey home is well known. The 1995 Ron Howard/Universal Pictures film, “Apollo 13,” takes some artistic license, but is generally accurate and realistic.
Five years before Apollo 13 was launched, an engineering decision had been made to increase the spacecraft electrical system from 28 volts to 65 volts. This required that every electrical component on the vehicle had to be changed to accommodate the increased power. The after-accident investigation found that the team that designed the cooling fans for the oxygen tanks was never informed of the change.
During the actual flight, the wiring inside the tank heated to approximately 1,000 °F. (538 °C.), and in the pressurized pure oxygen, the insulation caught fire. The tank, originally installed on Apollo 10, had been dropped when it was removed for modification. It was repaired and later used on Apollo 13, however, it had been weakened by the damage. The extreme pressure caused by the heat of the burning electrical wiring in the containment caused the tank to rupture.
¹ Serial number 10024X-TA0009
² The official mission transcript attributes this statement to Jim Lovell, however, in Lovell’s recollection, it was made by Swigert.
11 April 1970: At 2:13:00 p.m., Eastern Standard Time, Apollo 13 was launched from Launch Complex 39A at the Kennedy Space Center, Cape Canaveral, Florida. This mission was planned to be the third manned lunar landing. The destination was the Fra Mauro Highlands. In command was Captain James A. Lovell, Jr., United States Navy. The Command Module Pilot was John L. “Jack” Swigert, Jr. (who was originally scheduled as the backup CSM pilot, but had replaced Lieutenant Commander T. Kenneth Mattingly II, USN, just three days before launch). and the Lunar Module Pilot was Fred W. Haise, Jr., A NASA astronaut (formerly a U.S. Marine Corps and U.S. Air Force fighter pilot, test pilot and instructor).
The crew change had been made because it was believed that Ken Mattingly had been exposed to measles and NASA administrators did not want to risk that he might become ill during the flight.
At T + 000:05:30.64, while accelerating toward Earth orbit, the center J-2 engine on the Saturn S-II second stage shut down 2 minutes, 12.36 seconds early, which required the other four engines to increase their burn by 34.53 seconds, and the S-IVB third stage engine had to burn 9 seconds seconds longer than planned to achieve the necessary velocity for orbital insertion.
The Apollo 13 mission did not go as planned. An explosion inside the service module was a very near disaster, and the lunar landing had to be aborted. Returning the three astronauts safely to Earth became the primary task.
The Saturn V rocket was a three-stage, liquid-fueled heavy launch vehicle. Fully assembled with the Apollo Command and Service Module, it stood 363 feet (110.642 meters) tall. The first and second stages were 33 feet (10.058 meters) in diameter. Fully loaded and fueled the rocket weighed 6,200,000 pounds (2,948,350 kilograms). It could lift a payload of 260,000 pounds (117,934 kilograms) to Low Earth Orbit.
The first stage was designated S-IC. It was designed to lift the entire rocket to an altitude of 220,000 feet (67,056 meters) and accelerate to a speed of more than 5,100 miles per hour (8,280 kilometers per hour). The S-IC stage was built by Boeing at the Michoud Assembly Facility, New Orleans, Louisiana. It was 138 feet (42.062 meters) tall and had an empty weight of 290,000 pounds (131,542 kilograms). Fully fueled with 203,400 gallons (770,000 liters) of RP-1 and 318,065 gallons (1,204,000 liters) of liquid oxygen, the stage weighed 5,100,000 pounds (2,131,322 kilograms). It was propelled by five Rocketdyne F-1 engines, producing 1,522,000 pounds of thrust, each, for a total of 7,610,000 pounds of thrust at Sea Level. These engines were ignited seven seconds prior to lift off and the outer four burned for 168 seconds. The center engine was shut down after 142 seconds to reduce the rate of acceleration. The F-1 engines were built by the Rocketdyne Division of North American Aviation at Canoga Park, California.
The S-II second stage was built by North American Aviation at Seal Beach, California. It was 81 feet, 7 inches (24.87 meters) tall and had the same diameter as the first stage. The second stage weighed 80,000 pounds (36,000 kilograms) empty and 1,060,000 pounds loaded. The propellant for the S-II was liquid hydrogen and liquid oxygen. The stage was powered by five Rocketdyne J-2 engines, also built at Canoga Park. Each engine produced 232,250 pounds of thrust, and combined, 1,161,250 pounds of thrust.
The Saturn V third stage was designated S-IVB. It was built by Douglas Aircraft Company at Huntington Beach, California. The S-IVB was 58 feet, 7 inches (17.86 meters) tall with a diameter of 21 feet, 8 inches (6.604 meters). It had a dry weight of 23,000 pounds (10,000 kilograms) and fully fueled weighed 262,000 pounds. The third stage had one J-2 engine and also used liquid hydrogen and liquid oxygen for propellant. The S-IVB wou place the Command and Service Module into Low Earth Orbit, then, when all was ready, the J-2 would be restarted for the Trans Lunar Injection.
Eighteen Saturn V rockets were built. They were the most powerful machines ever built by man.