13 Things That Saved Apollo 13, Part 1: Timing

Damage to the Apollo 13 spacecraft from the oxygen tank explosion. Credit: NASA

Note: To celebrate the 40th anniversary of the Apollo 13 mission, for the next 13 days, Universe Today will feature “13 Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill. Click here for our preview article.

Oxygen Tank two in the Apollo 13 Service Module exploded at Mission Elapsed Time (MET) 55 hours and 55 minutes, 321,860 kilometers (199,990 miles) away from Earth. If the tank was going to rupture and the crew was going to survive the ordeal, the explosion couldn’t have happened at a better time. “Not everyone agrees with all the things I’ve come up with in my research,” said NASA engineer Jerry Woodfill who has studied the Apollo 13 mission in intricate detail, “but pretty much everyone agrees on this, including Jim Lovell. The timing of when the explosion happened was key. Much earlier or later in the mission would have prevented a successful rescue.”

If the explosion happened earlier (and assuming it would have occurred after Apollo 13 left Earth orbit), the distance and time to get back to Earth would have been so great that there wouldn’t have been sufficient power, water and oxygen for the crew to survive. Had it happened much later, perhaps after astronauts Jim Lovell and Fred Haise had already descended to the lunar surface, there would not have been the opportunity to use the lunar lander as a lifeboat.

But looking at why the explosion happened when it did shows how fortuitous the timing ended up to be.

The control panel of the Apollo 13 capsule. The module is on display at the Kansas Cosmosphere and Space Center in Hutchinson, KS. Photo courtesy Kansas Cosmosphere and Space Center.

The explosion occurred when Jack Swigert flipped a switch to conduct a “stir” of the O2 tank. The Teflon insulation on the wires to the stirrer motor in O2 tank 2 had unknowingly been damaged because the manufacturer failed to update the heater design for 65 volt operation, and the tank overheated during a pre-flight test, melting the insulation. The damaged wires shorted out and the insulation ignited. The resulting fire rapidly increased pressure beyond its nominal 1,000 psi (7 MPa) limit and either the tank or the tank dome failed.

The O2 tanks were stirred in order to get an accurate reading on the gauging systems, as the cryogenic oxygen tends to solidify in the tanks, and stirring allows for a more accurate reading on the quantity of O2 remaining in the tank.

But this was not the first time the crew had been ordered to stir the tank. It was the fifth time during the mission. And most interestingly, the tanks normally were stirred approximately once every 24 hours. So, why was it stirred that often?

In what Woodfill said was a problem unrelated to what caused the explosion, the quantity sensor or gauge was not working correctly on O2 tank 2. The EECOM (Electrical Environmental and Consumables) flight controller in Houston discovered that the quantity sensor was not reading accurately, and because of that Mission Control asked the astronauts to perform additional actuations of the stirrer to try and troubleshoot why the sensor wasn’t working correctly.

So, it took five actuations until the short circuit and the resulting fire and explosion occurred. If the gauge had been working correctly and the normal stirring of the tank had been done, that would have put the time of the fifth stirring after Lovell and Haise had departed for the lunar surface, and the rescue scenario that ultimately was carried out couldn’t have happened.

“Check the arithmetic,” said Woodfill. “Five actuations at 24 hour periods amounts to a MET of 120 hours. The lunar lander would have departed for the Moon at 103.5 hours into the mission. At 120 hours into the mission, the crew of Lovell and Haise would have been awakened from their sleep period, having completed their first moon walk eight hours before. They would receive an urgent call from Jack Swigert and/or Mission Control that something was amiss with the mother ship orbiting the Moon.”

Apollo 13 crew: Jim Lovell, Jack Swigert and Fred Haise. Credit: NASA

Who knows what would have happened to the crew? The fuel cells required the liquid oxygen tanks. This meant no production of electrical power, water and oxygen. The attached lunar lander had to be available. Likely, the two ships couldn’t even have docked back together. And what if the accident had happened behind the Moon without mission control’s help? Alone in the Command module, Swigert would have had difficulty analyzing the problem. Without a fueled lunar lander descent stage attached, lacking its consumables and engines as well as the needed battery power, water and oxygen, the crippled Command Module could not have returned to Earth with live astronaut(s). Not only would Lovell and Haise have perished but Swigert’s fate would have been the same. Even if the damaged Service Module’s engine had worked, no fuel cells meant the ship would die. The situation that the Apollo 13 crew actually faced was dire, but the alternative scenario would certainly have been fatal.

Woodfill contends that the quantity sensor malfunction assured the lunar lander would be present and fully fueled at the time of the disaster. It was an extremely fortuitous event. Had it not occurred, the timing of the explosion would have been far different and the crew would have perished.

Additional Articles from the “13 Things That Saved Apollo 13” series that have now been posted:

Introduction

Part 2: The Hatch That Wouldn’t Close

Part 3: Charlie Duke’s Measles

Part 4: Using the LM for Propulsion

Part 5: Unexplained Shutdown of the Saturn V Center Engine

Part 6: Navigating by Earth’s Terminator

Part 7: The Apollo 1 Fire

Part 8: The Command Module Wasn’t Severed

Part 9: Position of the Tanks

Part 10: Duct Tape

Part 11: A Hollywood Movie

Part 12: Lunar Orbit Rendezvous

Part 13: The Mission Operations Team

Also:

Your Questions about Apollo 13 Answered by Jerry Woodfill (Part 1)

More Reader Questions about Apollo 13 Answered by Jerry Woodfill (part 2)

Final Round of Apollo 13 Questions Answered by Jerry Woodfill (part 3)

Never Before Published Images of Apollo 13’s Recovery

Listen to an interview of Jerry Woodfill on the 365 Days of Astronomy podcast.

13 Things that Saved Apollo 13

The crew of Apollo 13 after landing safely. Credit: NASA.

On the night of April 13th, 1970, when the oxygen tank in Apollo 13’s Command and Service Module exploded, a 27-year-old engineer named Jerry Woodfill sat at his console in the Mission Evaluation Room at Johnson Space Center, monitoring the caution and warning system he helped create for the Apollo spacecraft.

“It was 9:08 pm, and I looked at the console because it flickered a few times and then I saw a master alarm come on,” Woodfill said, talking from his office at JSC where he has worked for almost 45 years. “Initially I thought something was wrong with the alarm system or the instrumentation, but then I heard Jack Swigert in my headset: “Houston, we’ve had a problem,” and then a few moments later, Jim Lovell said the same thing.”

And so began the most perilous but eventually triumphant situation ever encountered in human spaceflight.

2010 is the 40th anniversary of Apollo 13, and Universe Today had the chance to talk with Woodfill about his role in Apollo 13, a mission which many believe should have ended fatally for astronauts Jim Lovell, Fred Haise, and Jack Swigert. But it didn’t, and the mission has come to be called a “successful failure.”

What things were responsible for that success – the overcoming of odds – to rescue of the crew?

Since Woodfill was there in the thick of the action, he has some ideas on how to answer that question. But also, for the past 40 years he has studied the Apollo13 mission in intricate detail, examining all the various facets of the rescue by going through flight transcripts, debriefs, and other documents, plus he’s talked to many other people who worked during the mission. Fascinated by the turn of events and individuals involved who turned failure into success, Woodfill has come up with what he calls “13 Things That Saved Apollo 13.”

Over the next few weeks, we’ll share Woodfill’s insights and discuss each of those 13 turning points. What better way to celebrate the 40th anniversary of Apollo 13!

But for today, besides giving our readers a preview of what is to come the next 13 days, we’ll take this opportunity introduce you to Jerry Woodfill.

Jerry Woodfill working in the Apollo Mission Evaluation Room. Credit: Jerry Woodfill.

While attending Rice University on a basketball scholarship, Woodfill was inspired by President John F. Kennedy’s famous “We Choose to go to the Moon” speech delivered at Rice. Woodfill turned in his basketball shoes and focused on his studies of electrical engineering, hoping to become part of the space program.

He came on board at NASA just in time to work on helping to build the Apollo spacecraft.

“I spent years working with contractors, engineers, flight controllers and astronauts on the caution and warning system, or the alarm systems for both the lunar lander as well as the command ship,” Woodfill said.

He compared the alarm system to the lights that come on in an automobile when the battery is low or the generator isn’t working. “We had to come up with the best means of telling the astronauts they had a problem. We had to make sure the alarm system worked right. ”

Woodfill said that like most of the NASA team, he knew the workings of the command ship and lander more intimately than any of his college courses would have required, but that prepared him for any problems that might arise.

The Mission Evaluation Room. Credit: Jerry Woodfill.

During the Apollo missions Woodfill worked in the Mission Evaluation Room, which is NOT the Mission Operations Control Room (MOCR) or “Mission Control” as it is known. MER was in a building adjacent to the Mission Control building. Woodfill has written a webpage detailing the difference between the MER and MOCR.

“We were an unsung group,” Woodfill said. “We were there for mission support. We weren’t flight controllers, but we were experts. For other missions that were routine we didn’t play that big of a role, but for the Apollo 13 mission, we did play a role.”

Woodfill tends to downplay both his role and the importance of the MER. “Comparing the 1970s era MER to the Mission Operations Control Room would be akin to comparing the Queen Mary to a weekend boater’s cabin cruiser,” he said. “Likewise, comparing my role in the rescue to Gene Kranz and Glen Lunney’s would be more incomparable.”

For a truly unbiased opinion, however, Chapter 11 of Jim Lovell’s book “Lost Moon” (renamed Apollo 13 after the movie of the same name came out in 1995) details how important the people in the Mission Evaluation Room were. Yes, the “MER-men” were important!

While many may say the way Apollo 13 turned out was luck or a fortuitous turn of events, Woodfill said he tends to lean towards providence.

Over the next 13 days, perhaps we’ll find out!

And if Woodfill’s name is familiar to Universe Today readers, you may recall how he found the “lost” lesson plans of the teacher in space, Christa McAuliffe, and brought them “back to life” so to speak, as they are now being used by many teachers and Challenger Learning Centers.

Listen to an interview of Jerry Woodfill that I did for the 365 Days of Astronomy podcast.

Additional Articles in the “13 Things That Saved Apollo 13” that have now been posted:

Part 1: Timing

Part 2: The Hatch That Wouldn’t Close

Part 3: Charlie Duke’s Measles

Part 4: Using the LM for Propulsion

Part 5: Unexplained Shutdown of the Saturn V Center Engine

Part 6: Navigating by Earth’s Terminator

Part 7: The Apollo 1 Fire

Part 8: The Command Module Wasn’t Severed

Part 9: Position of the Tanks

Part 10: Duct Tape

Part 11: A Hollywood Movie

Part 12: Lunar Orbit Rendezvous

Part 13: The Mission Operations Team

Also:

Your Questions about Apollo 13 Answered by Jerry Woodfill (Part 1)

More Reader Questions about Apollo 13 Answered by Jerry Woodfill (part 2)

Final Round of Apollo 13 Questions Answered by Jerry Woodfill (part 3)

Never Before Published Images of Apollo 13’s Recovery

Fate of Apollo 13 Crew Might Have Been Much Different Than Originally Thought

When the crippled Apollo 13 spacecraft returned to Earth following their aborted moon mission in 1970, no one really knew if the command module would come in at the proper angle to avoid burning up in the atmosphere or even skip off the atmosphere and be bounced out into space. If the CM did skip off, the crew might be destined to spend a fatal eternity out in space. Or would they? Author Andrew Chaikin, who wrote the Apollo chronicle “A Man on the Moon,” asked Analytical Graphics lnc. (AGI) to do a computer simulation of what would have happened, and they found things could have been much different than originally thought. Watch this video, narrated by Chaikin to find out.

April 2010 will be the 40th anniversary of Apollo 13.
Continue reading “Fate of Apollo 13 Crew Might Have Been Much Different Than Originally Thought”

Apollo 13 Pictures

Apollo launch

Here are some Apollo 13 pictures. You can make any of these pictures into your computer desktop background. Just click on an image to enlarge it, and then right-click and choose “Set as Desktop Background.

Here’s a photo of the Apollo 13 mission launching from Florida’s Cape Canaveral. It launched on April 11, 1970, just a few days before its accident in space, which has been turned into a popular movie.

splashdown

This is an image of the Apollo 13 re-entry capsule returning to Earth, slowed by three large parachutes. Because of the accident, Apollo 13 kept its lunar lander attached to the Command Module for the entire trip around the Moon and back to Earth. They jettisoned it at the last minute just before re-entering the atmosphere.

lifted aboard a helicopter

Here’s a photo of the Apollo 13 capsule floating on the ocean after its landing. You can see command module pilot John L. Swigert Jr being lifted up by a helicopter.

lovell

And here’s a photo of Commander Jim Lovell being lifted up into the helicopter. He was the last of the three astronauts lifted up to safety after their capsule landed in the ocean.

command module

This is an image of the Apollo 13 command module, which was normally used by the astronauts through the mission. Their command module had to be powered down to save power so they had to use the service module after the accident.

We’ve written many articles about Apollo 13 for Universe Today. Here’s an article about what really happened on Apollo 13, and here’s an article about the Apollo 13 launch.

If you’d like more information on Apollo 13, here’s a link to NASA’s Apollo 13 mission page, and here’s more information on the accident.

We’ve recorded an episode of Astronomy Cast about the NASA capsules. Listen here, Episode 124: Space Capsules.

What Really Happened on Apollo 13?

Apollo 13 crew reflects on the mission from David Meerman Scott on Vimeo.

Hear the story of what really happened on Apollo 13 from two of the astronauts who were on board, Jim Lovell and Fred Haise. Lovell provides great detail on the history of the oxygen tank and why it exploded, and both Lovell and Haise have some great stories to share about the flight, movie inaccuracies and more. Thanks to David Meerman Scott from Apollo Artifacts who took this video at the Kennedy Space Center at the Astronaut Scholarship Foundation event on November 6, 2009.

Also on Apollo Artifacts, check out a video of short speech by Neil Armstrong who gave a tribute to the Apollo 12 crew at the flight’s 40th anniversary gala on November 7, 2009.