13 Things That Saved Apollo 13, Part 2: The Hatch That Wouldn’t Close

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

When the oxygen tank exploded on the Apollo 13 Command Module, the astronauts on board and everyone in Mission Control had no idea what the problem was. In his book, “Lost Moon,” Apollo 13 commander Jim Lovell thought the “bang-whump-shudder” that shook the spacecraft could have been a rogue meteor hit on the lunar module, Aquarius. Quickly, he told Jack Swigert to “button up” or close the hatch between the Command Module Odyssey, and Aquarius, so that both spacecraft wouldn’t depressurize.

But the hatch wouldn’t close.

Apollo engineer Jerry Woodfill believes the balky hatch was one of the things that helped save the Apollo 13 crew. “They were trying to close off the only way they could save their lives,” he said.

In Mission Control and in the nearby Mission Evaluation Room, several engineers, including Woodfill, thought the only explanation for so many systems to go offline at once was an instrumentation problem. “Initially I thought there was something wrong with the alarm system or the instrumentation,” said Woodfill, who helped develop the alarm system for the Apollo spacecraft. “There was no way so many warning lights could illuminate at once. I was sure I would have some explaining to do about the system.”

Screenshot from Apollo 13 footage of Fred Haise floating through the hatch between Odyssey and Aquarius. Credit: NASA

At first, Lovell thought Fred Haise may have been playing a joke on the crew by actuating a relief valve that made a sort of popping noise – something he had done previously during the flight. But with the surprised look on Haise’s face, along with the noise and all the alarms going off, Lovell’s next thought was the hull had been compromised in Aquarius.

Like a submarine crew that closes hatches between compartments after being hit by a torpedo or depth charge, Lovell wanted to close the hatch into the Command Module so all the air didn’t rush out into the vacuum of space.

Swigert quickly tried three times to close the hatch, but couldn’t get it to lock down. Lovell tried twice, and again couldn’t get it to stay closed. But by that time, Lovell thought, if the hull had been compromised, both spacecraft surely would have already depressurized and no such thing was happening. So, the crew set the hatch aside and moved on to looking at the falling gauges on the oxygen tanks.

And shortly after that, Lovell looked out the window and saw a cloud of oxygen venting out into space.

Earlier in the flight, the Apollo 13 crew had opened the hatches between Odyssey and Aquarius, and actually was far ahead on their checklist of preparing to land on the Moon by turning on equipment in the lander.

Woodfill believes this was fortuitous, as was the hatch not closing, because saving time was of the essence in this situation.

“Some people say that doesn’t amount to much time,” Woodfill said, “but I say it did, because if they had closed and latched up the hatch, and then worked to find the real problem of what was wrong, then they would have to delay and quit working the problem to go remove the hatch, stow the hatch and go power up the lander.”

Why was time so important?

The fuel cells that created power for the Command Module were not working without the oxygen from the two tanks. “Tank 2, of course, was gone with the explosion,” said Woodfill,” and the plumbing on Tank 1 was severed, so the oxygen was bleeding off from that tank, as well. Without oxygen you can’t make the fuel cells work, and with both fuel cells gone they know they can’t land on the Moon. And then it became a question of whether they can live.”

But over in Aquarius, all the systems were working perfectly, and it didn’t take long for Mission Control and the crew to realize the lunar module could be used as a lifeboat.

Screenshot from Apollo 13 footage of Jim Lovell and Jack Swigert during the mission. Credit: NASA

However, all the guidance parameters which would help direct the ailing ship back to Earth were in Odyssey’s computers, and needed to be transferred over to Aquarius. Without power from the fuel cells, they needed to keep the Odyssey alive by using the reentry batteries as an emergency measure. These batteries were designed to be used during reentry when the crew returned to Earth, and were good for just a couple of hours during the time the crew would jettison the Service Module and reenter with only the tiny Command Module capsule.

“Those batteries are not ever supposed to be used until they got ready to reenter the Earth’s atmosphere,” said Woodfill. “If those batteries had been depleted, that would have been one of the worst things that could have happened. The crew worked as quickly as they could to transfer the guidance parameters, but any extra time or problem, and we could have been without those batteries. Those batteries were the only way the crew could have survived reentry. This is my take on it, but the time saved by not having to re-open the hatch helped those emergency batteries have just enough power in them so they could recharge them and reenter.”

It’s interesting when the hatch had to work correctly, when the lander was jettisoned for re-enty, it worked perfectly. But at the time of the explosion, it’s malfunctioning kept the pathway to survival into the LM open, saving time. Being able to get into the lunar lander quickly was what helped save the crew’s life.

Tommorow: Part 3: The measles

Additional articles from the “13 Things That Saved Apollo 13”
series:

Introduction

Part 1: Timing

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, Part 1: Timing

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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

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