50th Anniversary: NASA's Most Successful Failure

                                
Apollo 13 Service Module, as seen from the Lunar Excursion Module (LEM), Aquarius, as the Service Module was jettisoned just hours before the Command Module, Odyssey, returned to Earth. This photograph shows the damage caused by the oxygen tank explosion.
(Image Sources: NASA, Wikipedia.org, By NASAScan by Kipp Teague - Apollo 13 Image Library (image link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=71871333)

By Glenn A. Walsh

Reporting for SpaceWatchtower

What could have been a second tragedy for America's Space Program became, what has been called by NASA Astronaut Jim Lovell, NASA's “successful failure.” NASA's planning and ingenuity, following the explosion of an oxygen tank as the Apollo 13 spacecraft, with astronauts Jim Lovell, Jack Swigert, and Fred Haise, cruised toward the Moon, ended the Moon mission but brought the astronauts home safely.

It was exactly 50 years ago, as of the posting of this blog-post, on Monday, 1970 April 13 at 10:07:53 p.m. Eastern Standard Time (EST) / April 14, 3:07:53 Coordinated Universal Time (UTC) that the Apollo 13 Service Module's No. 2 Oxygen Tank exploded, which also caused Oxygen Tank No. 1 to fail. As Daylight Saving Time did not begin until the last Sunday in April (April 26) in 1970, today this time equates to 11:07:53 p.m. Eastern Daylight Saving Time (EDT).

This occurred less than a year after the triumphant Apollo 11 mission, when the first two humans, Neil Armstrong and Buzz Aldrin, landed and walked on the Moon on 1969 July 20. It also occurred nearly a half-year (in November of 1969) after the mission of Apollo 12, the second flight to land astronauts on the Moon. And, just a little more than two years after the Apollo 8 mission, when three astronauts successfully orbited another planetary body, the Earth's Moon, for the first time in history on Christmas Eve in 1968.

It also occurred a little more than three years after NASA's first tragedy, when astronauts Gus Grissom, Ed White, and Roger Chaffee were killed when a flash-fire engulfed their Apollo 1 space capsule during a pre-launch ground test on 1967 January 27. In later years, NASA would experience two more tragedies when astronauts would die with the explosion of the Challenger Space Shuttle on 1986 January 28 and the re-entry dis-integration of the Space Shuttle Columbia on 2003 February 1.

The loss of oxygen to Outer Space, from the two oxygen tanks, meant that the Apollo 13 astronauts no longer had that oxygen to breathe or to generate spacecraft electricity. The Apollo 13 Service Module, where the explosion occurred, was no longer operable. The Command Module, which housed the three astronauts during the flight to the Moon, had to be shut-down to preserve its limited resources for re-entry when returning to Earth.

So, the astronauts had to use the Lunar Excursion Module (LEM) as a lifeboat for their trip back to Earth, as the LEM had fully-charged batteries and full oxygen tanks. With its own life systems, and now that the Moon mission had been scrubbed, the LEM was available for the mission of keeping the astronauts alive for the trip back to Earth.

NASA had anticipated the possible need to use the LEM for this purpose, but had always considered the need unlikely. Had the oxygen tank explosion occurred on the return trip to Earth, after the LEM had been used to reach the Moon and then jettisoned before leaving lunar orbit, the astronauts would have had no lifeboat and would have perished in Deep Space.

But, there were two problems. First, the LEM was designed to house two astronauts on the short trip to the lunar surface and accomodate them for two days. Now, the LEM would have to house three astronauts for several extra days.

Second, the LEM was not designed to return to Earth, as it had no shielding for re-entering the Earth's atmosphere. So, the astronauts could ride the LEM all the way to the Earth's atmosphere. But to return to our planet, they would have to move back into the Command Module (the only part of the spacecraft with shielding that would allow them to re-enter the atmosphere) and jettison the LEM and the Service Module.

Consequently, the trip back to Earth was a difficult one for the crew. There was limited electrical power, a shortage of drinking water, and the LEM cabin was chilly and damp.

The removal of carbon dioxide from the LEM cabin became a critical item of concern, as the Command Module's cartridges for removing carbon dioxide were not compatible with the LEM system. NASA ground controllers and the crew were able to improvise a solution to this problem.

To return the astronauts to Earth, NASA had two options. The “direct abort” return path would return the astronauts to Earth before reaching the Moon. But, it was not known whether the explosion had damaged the Service Module's main propulsion system, and whether the Service Module's fuel cells could last long enough to implement this option.

So, NASA controllers decided Apollo 13 should take the longer route, by swinging around the Moon before returning to Earth. Consequently as the spacecraft swung around the Moon, on 1970 April 14 at 7:21 p.m. EST / April 15, 0:21 UTC, Apollo 13 traveled farther from the Earth than any other spacecraft with a human crew: 248,655 statute miles / 400,171 kilometers from Earth, a record held to this day in the Guinness Book of World Records.

Following Apollo 13's return to Earth, NASA set-up an investigative review board to determine what happened and what changes should be made to prevent future such problems. The investigation found fault with pre-flight testing of the oxygen tanks and the fact that flammable Teflon and aluminum were used inside the tanks storing very combustible oxygen.

Oxygen tanks were re-designed for Apollo 14 and subsequent missions. Thermostats were upgraded. As stirring fans had to be removed, a third oxygen tank was added in a different location to isolate it from the other two tanks and the fuel cells; this would ensure that no tank went below half-full.

All electrical wiring would now be sheathed in stainless steel, and the fuel cell oxygen supply valves were redesigned. Monitoring systems, in both the spacecraft and in Mission Control, were beefed-up to allow for earlier alert of potential problems. An emergency supply of 5 gallons / 19 liters of water was added to the Command Module, and an emergency battery was added to the Service Module. And, transfers of electrical power between the Command and Lunar Excursion Modules were made easier.

Although Apollo 13 did not land on the Moon, some mission experiments were completed. One experiment allowed the Saturn V rocket third stage to slam into the Moon, as a good test of the nuclear-powered seismograph left on the Moon by Apollo 12 (the solar-powered seismograph left on the Moon by Apollo 11 did not survive the first two-week lunar night); previous missions had sent the third stage into solar orbit.

An experiment to measure the amount of atmospheric electrical phenomena during the launch to Earth orbit (Apollo 12 had been struck by lightning shortly after launch) indicated a greater risk during marginal weather. A series of photographs taken by Apollo 13 confirmed that that Earth cloud heights could be determined by synchronous satellites.

The Apollo 13 mission objective was to explore the Moon around the area known as Fra Mauro. This mission was re-assigned to Apollo 14.

For post-flight educational goals, some Command Module interior components were displayed at the Museum of Natural History and Science (now known as the Kentucky Science Center) in Louisville until the year 2000. The exterior shell of the Command Module was displayed at the Musée de l'air et de l'espace (English: Air and Space Museum) in Paris. Later, the Command Module shell and internal components were reassembled and are now on display at the Cosmosphere museum in Hutchinson, Kansas.

Internet Links to Additional Information ---

Apollo 13 -
Link 1 >>> https://www.nasa.gov/mission_pages/apollo/missions/apollo13.html
Link 2 >>> https://www.youtube.com/watch?v=VIiZyBbZ2Dk
Link 3 >>> https://en.wikipedia.org/wiki/Apollo_13

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Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Monday, 2020 April 13.

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gaw

Glenn A. Walsh, Informal Science Educator & Communicator:
< http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
SpaceWatchtower Editor / Author: < http://spacewatchtower.blogspot.com/ >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >