Apollo 13 images via NASA. Montage by Judy Schmidt.
To celebrate the 45th anniversary of the Apollo 13 mission, Universe Today is featuring “13 MORE Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill.
During the first two days of the Apollo 13 mission, it was looking like this was going to be the smoothest flight of the program. As Capcom Joe Kerwin commented at 46:43 Mission Elapsed Time (MET), “The spacecraft is in real good shape as far as we are concerned. We’re bored to tears down here.”
Everything was going well, and in fact the crew was ahead of the timeline. Commander Jim Lovell and Lunar Module Pilot Fred Haise had entered the Aquarius Lunar Module 3 hours earlier than the flight plan had scheduled, wanting to check out the pressure in the helium tank – which had given some erroneous readings in ground tests before the launch. Everything checked out OK.
Opening up Aquarius early may have been one more thing that saved Apollo 13, says NASA engineer Jerry Woodfill.
“The first time the hatches between both vehicles are opened is a time consuming process,” Woodfill told Universe Today. “It’s as though a bank teller is requested to provide a customer access to a safety deposit box behind two locked vault doors.”
The removable hatch in the Odyssey Command Module had to be tied down and stowed before entering the tunnel for access to the second door, the lander’s entry hatch. Time was required for pressure equalization process so that the tunnel, command ship and lander were at one uniform pressure.
Often, there was a putrid, burnt insulation odor when the hatch to the LM was first opened, as previous crews described, so normally time was allowed for the smell to dissipate. All of these tasks were dealt with by about 55 hours MET, much earlier than originally planned. For some reason, the LM Pilot even brought the lander’s activation check list back into the command ship for study, though activation was scheduled hours away.
“Perhaps, this would be Fred Haise’s bedtime book to read preparing himself for sleep,” Woodfill said.
Flight Director Gene Kranz (closest to the camera) watches Fred Haise on a screen in Mission Control during a broadcast back to Earth, just 17 minutes and 42 seconds before the explosion. Credit: NASA.
But first, the crew provided a 49-minute TV broadcast showing how easily they moved about in weightlessness in the cramped spacecraft.
Then, it happened. Nine minutes later, at 55:54:56 MET, came the explosion of the oxygen tank in the Service Module. Despite ground and crew efforts to understand the problem, confusion reigned.
13 minutes after the explosion, Lovell looked out one of Odyssey’s windows and reported, “We are venting something out into space,” and quickly the crew and ground controllers knew they were losing oxygen. Without oxygen, the fuel cells that provided all the power to the CM would die. Tank 2, of course, was gone with the explosion and the plumbing on Tank 1 was severed, so the oxygen was bleeding off from that tank, as well.
Capcom Jack Lousma speaks to the crew of Apollo 13 from Mission Control. Credit: NASA.At one hour, 29 seconds after the explosion, the new Capcom Jack Lousma said after instructions from Flight Director Glynn Lunney, “[The oxygen] is slowly going to zero, and we are starting to think about the LM lifeboat.” From space, astronaut Jack Swigert replied, “That’s what we have been thinking about too.”
At that point, only fifteen minutes of power remained in the Command Module.
“Fifteen minutes more and the entire assemblage might have been a corpse with no radio, no guidance, no oxygen flowing into the cabin to keep Lovell, Haise and Swigert alive,” said Woodfill. “Certainly, it was fortuitous circumstances that led to opening the LM early. Simply consider how much time it would have taken to remove both hatches, stabilize and inspect the tunnel and lander interior. Add to this the time required to power up the lander’s life support systems. As it was, they had an open pathway into a safe haven, a lifeboat, called the lunar lander, crucial to survival.”
If the LM had not been opened, the crew would have likely run out of time before the Command Module’s batteries died, which would have created several problems.
As we discussed five years ago in one of the original “13 Things” articles, 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 kept 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 limited number of hours during the time the crew would jettison the Service Module and reenter with only the tiny Command Module capsule.
“Those batteries were 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 open up the Lunar Module helped those emergency batteries have just enough power in them so they could recharge them and reenter.”
By 58:40 MET, the guidance information from the Command Module computer had been transferred to the LM guidance system, the LM was fully activated and the Command and Service Module systems were turned off.
Mission Control and the crew had successfully managed the first of many “seat of the pant” procedures they would need to do in order to bring the crew of Apollo 13 back home.
Apollo 13 images via NASA. Montage by Judy Schmidt.
To celebrate the 45th anniversary of the Apollo 13 mission, Universe Today is featuring “13 MORE Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill.
Very quickly after the explosion of Oxygen Tank 2 in Apollo 13’s service module, it became apparent the Odyssey command module was dying. The fuel cells that created power for the Command Module were not working without the oxygen. But over in the Aquarius lunar lander, all the systems were working perfectly. It didn’t take long for Mission Control and the crew to realize the Lunar Module could be used as a lifeboat.
The crew quickly powered up the LM and transferred computer information from Odyssey to Aquarius. But as soon as they brought the LM communications system on line another problem developed.
The Apollo 13 crew couldn’t hear Mission Control.
Screenshot from Apollo footage of Jim Lovell and Jack Swigert. Credit: NASA
The crew radioed they were getting lots of background static, and at times, they reported communications from the ground were “unreadable.”
Additionally, the Manned Space Flight Network (MSFN) tracking stations around the world were having trouble “hearing” the Apollo 13 spacecraft’s radio broadcasting the tracking data.
“Without reliable knowledge of where the vehicle was or was going might result in disaster,” said NASA engineer Jerry Woodfill.
What was going on?
The dilemma was that two radio systems were using the same frequency. One was the transmitter from the LM’s S-band antenna. The other was the broadcast from the spent third stage of the Saturn V, known as the S-IVB.
The seismic station at the Apollo 12 site. The seismometer monitors the level of ground motion to detect arriving seismic waves. The instrument (left) is protected by metal foil against the varying temperatures on the lunar surface that produce large thermal stresses . Credit: NASA
As part of a science experiment, NASA had planned for crashing Apollo 13’s S-IVB into the Moon’s surface. The Apollo 12 mission had left a seismometer on the Moon, and an impact could produce seismic waves that could be registered for hours on these seismometers. This would help scientist to better understand the structure of the Moon’s deep interior.
In Apollo 13’s nominal flight plan, the lander’s communications system would only be turned on once the crew began preparing for the lunar landing. This would have occurred well after the S-IVB had crashed into the Moon. But after the explosion, the flight plan changed dramatically.
The flight profile of an Apollo mission to the Moon, distances not to scale. Note the Saturn V 3rd stage flight path. Credit: NASA.
But with both the Saturn IVB and the LM’s transmitters on the same frequency, it was like having two radio stations on the same spot on the dial. Communications systems on both ends were having trouble locking onto the correct signal, and instead were getting static or no signal at all.
The Manned Space Flight Network (MSFN) for the Apollo missions had three 85 foot (26 meter) antennas equally spaced around the world at Goldstone, California, Honeysuckle Creek, Australia and Fresnedillas (near Madrid), Spain.
According to historian Hamish Lindsay at Honeysuckle Creek, there was initial confusion. The technicians at the tracking sites immediately knew what the problem was and how they could fix it, but Mission Control wanted them to try something else.
“The Flight Controllers at Houston wanted us to move the signal from the Lunar Module across to the other side of the Saturn IVB signal to allow for expected doppler changes,” Hamish quoted Bill Wood at the Goldstone Tracking Station. ”Tom Jonas, our receiver-exciter engineer, yelled at me, ‘that’s not going to work! We will end up locking both spacecraft to one up-link and wipe out the telemetry and voice contact with the crew.’”
At that point, without the correct action, Houston lost telemetry with the Saturn IVB and voice contact with the spacecraft crew.
But luckily, the big 64 meter Mars antenna at Goldstone was already being switched over to help with the Apollo emergency and “their narrower beam width managed to discriminate between the two signals and the telemetry and voice links were restored,” said Wood.
That stabilized the communications. But then it was soon time to switch to the tracking station at Honeysuckle Creek.
The Honeysuckle antenna by night. Photo by Hamish Lindsay.
There, Honeysuckle Creek Deputy Director Mike Dinn and John Mitchell, Honeysuckle Shift Supervisor were ready. Both had foreseen a potential problem with the two overlapping frequency systems and before the mission had discussed it with technicians at Goddard Spaceflight Center about what they should do if there was a communication problem of this sort.
When Dinn had been looking for emergency procedures, Mitchell had proposed the theory of getting the LM to switch off and then back on again. Although nothing had been written down, when the emergency arose, Dinn knew what they had to do.
“I advised Houston that the only way out of this mess was to ask the astronauts in the LM to turn off its signal so we could lock on to the Saturn IVB, then turn the LM back on and pull it away from the Saturn signal,” said Dinn.
It took an hour for Mission Control in Houston to agree to the procedure.
“They came back in an hour and told us to go ahead,” said Mitchell, “and Houston transmitted the instructions up to the astronauts ‘in the blind’ hoping the astronauts could hear, as we couldn’t hear them at that moment. The downlink from the spacecraft suddenly disappeared, so we knew they got the message. When we could see the Saturn IV downlink go way out to the prescribed frequency, we put the second uplink on, acquired the LM, put the sidebands on, locked up and tuned away from the Saturn IVB. Then everything worked fine.”
Dinn said they were able to “pull” the frequencies apart by tuning the station transmitters appropriately.
Technicians at the Honeysuckle Creek tracking station near Canberra, Australia work to maintain communications with Apollo 13. Credit: Hamish Lindsay.
This action, said Jerry Woodfill, was just one more thing that saved Apollo 13.
“The booster stage’s radio was de-turned sufficiently from the frequency of the LM S-Band so that the NASA Earth Stations recognized the signal required to monitor Apollo 13’s orbit at lunar distances,” explained Woodfill. “This was altogether essential for navigating and monitoring the crucial mid-course correction burn which restored the free-return trajectory as well as the set-up of the subsequent PC+2 burn to speed the trip home needed to conserve water, oxygen and water stores to sustain the crew.”
You can hear some of the garbled communications and Mission Control issuing instructions how to potentially deal with the problem at this link from Honeysuckle Creek’s website.
As for the S-IVB science experiment, the 3rd stage crashed successfully on the Moon, providing some of the first data for understanding the Moon’s interior.
Later, on hearing that the stage had hit the Moon, Apollo 13 Commander Jim Lovell said, “Well, at least one thing worked on this mission!”
(Actually, in spite of the Apollo 13 accident, a total of four science experiments were successfully conducted on Apollo 13.)
In early 2010, NASA’s Lunar Reconnaissance Orbiter spacecraft imaged the crater left by the Apollo 13 S-IVB impact.
On April 14th 1970, the Apollo 13 Saturn IVB upper stage impacted the moon north of Mare Cognitum, at -2.55° latitude, -27.88° East longitude. The impact crater, which is roughly 30 meters in diameter, is clearly visible in the Lunar Reconnaissance Orbiter Camera’s (LROC) Narrow Angle Camera image. Credit: NASA/Goddard/Arizona State University.
Thanks to space historian Colin Mackellar from the Honeysuckle Creek website, along with technician Hamish Lindsay and his excellent account of the Honeysuckle Creek Tracking station and their role in the Apollo 13 mission.
Apollo 13 images via NASA. Montage by Judy Schmidt.
To celebrate the 45th anniversary of the Apollo 13 mission, Universe Today is featuring “13 MORE Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill.
Understandably, it was chaotic in both Mission Control and in the spacecraft immediately after the oxygen tank exploded in Apollo 13’s Service Module on April 13, 1970.
No one knew what had happened.
“The Apollo 13 failure had occurred so suddenly, so completely with little warning, and affected so many spacecraft systems, that I was overwhelmed,” wrote Sy Liebergot in his book, Apollo EECOM: Journey of a Lifetime. “As I looked at my data and listened to the voice report, nothing seemed to make sense.”
But somehow, within 53 minutes of the explosion, the ship was stabilized and an emergency plan began to evolve.
“Of all of the things that rank at the top of how we got the crew home,” said astronaut Ken Mattingly, who was sidelined from the mission because he might have the measles, “was sound management and leadership.”
Gerry Griffin, Gene Kranz, and Glynn Lunney celebrate the Apollo 13 recovery. Credit: NASA.
By chance, at the time of the explosion, two Flight Directors — Gene Kranz and Glynn Lunney — were present in Mission Control. NASA engineer Jerry Woodfill feels having these two experienced veterans together at the helm at that critical moment was one of the things that helped save the Apollo 13 crew.
“The scenario resulted from the timing,” Woodfill told Universe Today, “with the explosion occurring at 9:08 PM, and Kranz as Flight Director, but with Lunney present to assume the “hand-off” around 10:00 PM. That assured that the expertise of years of flight control leadership was conferring and assessing the situation. The presence of these colleagues, simultaneously, had to be one of the additional thirteen things that saved Apollo 13. With Lunney looking on, the transition was as seamless as a co-pilot taking the helm from a pilot of a 747 passenger jet.”
Woodfill made an additional comparison: “Having the two Flight Directors on hand at that critical moment is like having Michael Jordan and Magic Johnson on a six-man basketball squad and the referee ignoring any fouls their team might make.”
“Gene was on the team before me and he had had a long day in terms of hours. …And shortly before his shift was scheduled to end is when the “Houston, we’ve got a problem” report came in. And at first, it was not terribly clear how bad this problem was. And one of the lessons that we had learned was, “Don’t go solving something that you don’t know exists.” You’ve got to be sure … So, it was generally a go slow, let’s not jump to a conclusion, and get going down the wrong path…. We had a number of situations to deal with.”
The “not jumping to conclusions” was equally expressed by Kranz when he told his team, “Let’s solve the problem, but let’s not make it any worse by guessing.”
The presence of Kranz and Lunney, simultaneously, is especially obvious reading Gene Kranz’s book, Failure Is Not an Option.
“Kranz captures the wealth of “brain power” present at the moment of the explosion,” said Woodfill. “Besides both Kranz and Lunney, their entire teams overlapped. Yes, there were two squads on the floor competing with the dire opponents who threatened the crew’s survival.”
The crew’s survival was foremost in the minds of the Flight Directors. “We will never surrender, we will never give up a crew,” Kranz said later.
Apollo astronauts at Mission Control during Apollo 13. Credit: NASA.
Perhaps, the most obvious evidence of how fortuitous the presence of both Kranz and Lunney was, Kranz recorded on page 316-317 of his book. The pair refuses to accept the more popular but potentially fatal decision (a direct abort) to speed the crew’s return to Earth using the damaged command ship’s engine. The direct abort would have been to jettison the lander and fire the compromised command ship’s engine to potentially quicken the return to Earth by 50 hours.
Mattingly recalled those early minutes in Mission Control after the explosion.
Ken Mattingly in Mission Control. Credit: NASA.
“The philosophy was ‘never get in the way of success,’” said Mattingly, speaking at a 2010 event at the Smithsonian Air and Space Museum. “We had choices, we debated about turning immediately around and coming home or going around the moon. In listening to all of those discussions, we never closed the door about any option of getting home. We didn’t know yet how we were going to get there, but you always make sure you don’t take a step that would jeopardize it.”
And so, with the help of their teams, the two Flight Directors quickly ran through all the options, the pros and cons, and – again – within 53 minutes after the accident they made the decision to have the crew continue their trajectory around the Moon.
Damage to the Apollo 13 spacecraft from the oxygen tank explosion. Credit: NASA
Later, when Jim Lovell commented on viewing the damaged Service Module when it was jettisoned before the crew re-entered Earth’s atmosphere — “There’s one whole side of that spacecraft missing. Right by the high gain antenna, the whole panel is blown out, almost from the base to the engine,” — it was indeed an ominous look at what might have ensued using it for a quick return to Earth.
By the end of the Lunney team’s shift about ten hours after the explosion, Mission Control had put the vehicle back on an Earth return trajectory, the inertial guidance platform had been transferred to the Lunar Module, and the Lunar Module was stable and powered up for the burn planned the would occur after the crew went around the Moon. “We had a plan for what that maneuver would be, and we had a consumable profile that really left us with reasonable margins at the end,” Lunney said.
Apollo 13’s view from Aquarius as it rounds the Moon, with the Command Module at right. Credit: NASA/Johnson Space Center.
“We had many problems here – we had a variety of survival problems, we had electrical management, water management, and we had to figure out how to navigate because the stars were occluded by the debris cloud surrounding the spacecraft. Basically we had to turn a two day spacecraft into a four and a half day spacecraft with an extra crewmember to get the crew back home. We were literally working outside the design and test boundaries of the spacecraft so we had to invent everything as we went along.”
A look at the transcripts of the conversations between Flight Controllers, Flight Directors and support engineers in the Mission Evaluation Room reveals the methodical working of the problems by the various teams. Additionally, you can see how seamlessly the teams worked together, and when one shift handed off to another, everything was communicated.
Lunney explains:
“The other thing I would say about it is, and we talked about Flight Directors and teams, equally important was the fact that, during those flights, we had this Operations team that you have seen in the Control Center in the back rooms around it and we sort of had our own way of doing things in our own team, and we were fully prepared to decide whatever had to be decided. But in addition to that, we had the engineering design teams that would follow the flight along and look at various problems that occurred and put their own disposition on them. …That was part of this network of support. People had their certain jobs to do. They knew what it was. They knew how they fit in. And they were anticipating and off doing it.”
Without the leadership of the Flight Directors, keeping the teams focused and on-task, the outcome of the Apollo 13 mission may have been much different.
“It is the experience of these two, Kranz and Lunney, working together which likely saved the crew from what might have been certain death,” said Woodfill.
Apollo 13 images via NASA. Montage by Judy Schmidt.
In our original series 5 years ago on the “13 Things That Saved Apollo 13,” the first item we discussed was the timing of the explosion. As NASA engineer Jerry Woodfill told us, 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.
An explosion earlier in the mission (assuming it would have occurred after Apollo 13 left Earth orbit) would have meant 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. An explosion later, perhaps after astronauts Jim Lovell and Fred Haise had already descended to the lunar surface, and all three crew members wouldn’t have been able to use the lunar lander as a lifeboat. Additionally, the two spacecraft likely couldn’t have docked back together, and without the descent stage’s consumables left on the Moon (batteries, oxygen, etc.) that would have been a fruitless endeavor.
Now, for our first article in our subsequent series “13 MORE Things That Saved Apollo 13,” we’re going to revisit that timing, but look more in detail as to WHY the explosion happened when it did, and how it affected the rescue of the crew. The answer lies with the failure of a pressure sensor in Oxygen Tank 2, an issue unrelated to the uninsulated wires in the tank that caused the explosion.
Apollo 13 crew: Jim Lovell, Jack Swigert and Fred Haise. Credit: NASA
Most who are familiar with the story of Apollo 13 are acquainted with the cause of the explosion, later determined by an accident investigation committee led by Edgar Cortright, Director of the Langley Research Center.
The tank had been dropped five years before the flight of Apollo 13, and no one realized the vent tube on the oxygen tank was jarred out of alignment. After a Count Down Demonstration Test (CDDT) conducted on March 16, 1970 when all systems were tested while the Apollo 13 spacecraft sat atop the Saturn V rocket on the launch-pad, the cold liquid oxygen would not empty out of Oxygen Tank 2 through that flawed vent pipe.
The normal approach was to use gaseous oxygen to push the liquid oxygen out of the tank through the vent pipe. Since that wasn’t working, technicians decided the easiest and quickest way to empty the liquid oxygen would be to boil it off using the heaters in the tank.
A graphic depicting the details of oxygen tank number 2 and the heater and thermostat unit. Credit: NASA.
“In each oxygen tank were heaters and a paddle wheel fan,” Woodfill explained. “The heater and fan (stirrer) device encouraged a portion of the cold liquid 02 to turn into a higher pressure 02 gas and flow into the fuel cells. A fan also known as the cryo-stirrer was powered each time the heater was powered. The fan served to stir the liquid 02 to assure it was uniformly consistent in density.”
To protect the heater from being overly hot, a switch-like device called a relay turned off heater power anytime the temperature exceeded 80 degrees F. Also, there was a temperature gauge which technicians on the ground could monitor if temperature exceeded 80 degree F.
The original Apollo spacecraft worked on 28 volts of electricity, but after the 1967 fire on the Launchpad for Apollo 1, the Apollo spacecraft’s electrical systems had been modified to handle 65 volts from the external ground test equipment. Unfortunately Beech, the tank’s manufacturer failed to change out this tank, and the heater safety switch was still set for 28 volt operation.
“When the heater was powered up to vent the tank, the higher voltage “fused” the relay contacts so that the switch could not turn off power when the temperature of the tank exceeded 80 degrees F (27 C),” said Woodfill.
Additionally, the temperature gauge on the ground test panel only went to 88 degrees F (29.5 C), so no one was aware of this excessive heat.
A graphic of the interior of the Apollo 13 Service Module and the location of the oxygen tanks relative to the other systems. Credit: NASA.
“As a result,” said Woodfill, “the heater and the wires which powered it reached estimated temperatures of around 1000 degrees F. (538°C), hot enough to melt the Teflon insulation on the heater wires and leave portions of them bare. Bare wires meant the potential for a short-circuit and an explosion since these wires were immersed in the liquid oxygen.”
Because the tank had been dropped, and because its heater design had not been updated for 65 volt operation, the tank was a virtual bomb, Woodfill said. Anytime power was applied to those heaters to stir the tank’s liquid oxygen, an explosion was possible.
At 55:54:53 Mission Elapsed Time (MET), the crew was asked to conduct a stir of the oxygen tanks. It was then that the damaged wires in Oxygen Tank 2 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.
But back to the quantity sensor on Oxygen Tank 2. For a reason yet to be understood, during the early part of the Apollo 13 flight, the sensor failed. Prior to launch, that Tank 2 quantity sensor was being monitored by the onboard telemetry system, and it apparently worked perfectly.
“The failure of that probe in space is, perhaps, the most important reason Apollo 13’s crew lived,” said Woodfill.
Here’s the explanation of why Woodfill makes that claim.
Cover to the Apollo 13 flight plan. Credit: NASA.
Woodfill’s research of Apollo 13 indicated that standard operating procedure (SOP) had Mission Control request a stirring of the cryos approximately every 24 hours. For the Apollo 13 mission, the first stir came about 24 hours into the mission (23:20:23 MET). Ordinarily, the next cryo stir would not be called for until 24 hours later. The heater-cryo stir procedure was done to assure accuracy of the quantity gauge and proper operation of the system through the elimination of O2 stratification. The sensor read more accurately because the stir made the liquid oxygen more uniform and less stratified. After the first stir, 87 % remaining oxygen quantity was indicated, a bit ahead of expectations. The next stir came about a day later, about 46:40 MET.
At the time of this second heater-cryo-stir, Oxygen Tank 2’s quantity sensor failed. Post mission analysis by the investigation committee indicated the failure was not related to the bare heater wires.
The loss of ability to monitor Oxygen Tank 2’s quantity caused mission control to radio to the crew: “(Because the quantity sensor failed,) we’re going to be requesting you stir the cryos every six hours to help gage how much 02 is in tank 2.”
However, Mission Control chose to perform some analysis of the situation in Tank 2 by calling for another stir, not at 53 hours MET but at 47:54:50 MET and still another at 51:07:41 . Because the other oxygen tank, Tank 1, indicated a low pressure, both tanks were stirred at 55:53.
“Count the number of stirs since launch,” Woodfill said. “1. at 23:20:23, 2. at 46:40, 3. at 47:54:50, 4. at 51:07:44 and 5. at 55:53. There were five applications of current to those bare heater wires. The last three occurred over a period of only 8 hours rather than 72 hours. Had it not been for the non-threatening failure of Tank 2’s quantity probe and the low pressure in O2 Tank 1, this would not have been the case.”
Woodfill explained that anyone who has analyzed hardware failures understands that the more frequent and shorter the period between operations of a flawed component hastens ultimate failure. NASA performs stress testing on hundreds of electrical systems using this approach. More frequent power-ups at shorter intervals encourages flawed systems to fail sooner.
The short circuit in Oxygen Tank 2 after the fifth heater-cryo-stir resulted in the explosion of Apollo 13’s Oxygen Tank 2. Had the normal sequence of stirs been performed at 24 hour intervals, and the failure came after the fifth stirring, the explosion would have occurred after the lunar module, the life boat, was no longer available.
“I contend that the quantity sensor malfunction was fortuitous and assured the lander would be present and fully fueled at the time of the disaster,” Woodfill said.
5 heater actuations at 24 hours periods amounts to a MET of 120 hours.
“The lunar lander would have departed for the Moon at 103.5 hours into the mission,” Woodfill said. “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.”
Furthermore, Woodfill surmised, analysis of Swigert’s ship’s problems would likely be clouded by the absence of his two crewmates on the lunar surface. Added problems for Mission Control would have been the interruption of communications each time the command ship went behind the Moon, interrupting the telemetry so crucial to analyzing the failure. When it became evident, the cryogenic system would no longer produce oxygen, water, and electrical power, those command module emergency batteries would have been activated. Likely, Mission Control would have ordered an abort of the lunar lander earlier, but, of course, that would have been futile. Had the tiny lander’s ascent stage rendezvoused and docked with the depleted CM, all the life supporting descent stage consumables would remain on the Moon.
“The nightmare would have the Apollo 13 crew saying their last farewells to their families and friends,” said Woodfill. “One can only speculate how the end might have come.”
And there likely would not have been Apollo 14, 15, 16 and 17 — at least not for a very long time.
Apollo 13 launch. Credit: NASA
Another aspect of the timing of the explosion that Woodfill has considered is, why didn’t the tank explode on the Launchpad?
Following the March 16 CDDT, no additional “power-up” or tests were planned. However, it is not uncommon for pre-launch re-verification to be performed.
“One such re-check might easily have been these heater circuits since they had been used in a non-standard way to empty the oxygen from the cryo tanks after the Countdown Demonstration Test (CDDT) weeks earlier,” Woodfill said. “Such re-do’s often occur for myriad reasons. For Apollo 13, despite the compromised system, none occurred until the craft was safely on its way to the Moon.”
However, such a routine re-test involving cryo stirring would have unknowingly jeopardized the launch vehicle, support persons, or astronaut crew.
Or, if the quantity sensor had failed on the ground, likely the same kind of trouble shooting that was done by Mission Control and the Apollo 13 crew, would have been performed by the KSC ground team.
Had the sensor failed at that time, a series of heater actuations/stirrings would have been executed to trouble-shoot the device.
“Of course, the result would have been the same kind of explosion nearly 55 hours 55 minutes after launch,” Woodfill said. “On the ground, the Apollo 13 explosion could have taken the lives of Lovell and crew if trouble-shooting had been done while the crew awaited launch.”
If the trouble-shooting had been done earlier, with several heater actuations/stirrings during the days before the launch, Woodfill said, “a terrible loss of life would have ensued with, potentially, scores of dedicated Kennedy Space Center aerospace workers bravely attempting to fix the problem. And the towering thirty-six story Saturn 5 would have collapsed earthward in a ball of fire reminiscent of that December 1957 demise of America’s Vanguard rocket.”
“Yes, the fact that the Oxygen Tank 2 quantity sensor did not fail on the launch pad, but failed early in the flight was one of the additional things that saved Apollo 13.”
Apollo 13 images via NASA. Montage by Judy Schmidt.
“Things had gone real well up to at that point of 55 hours, 54 minutes and 53 seconds (mission elapsed time),” said Apollo 13 astronaut Fred Haise as he recounted the evening of April 13, 1970, the night the Apollo 13’s command module’s oxygen tank exploded, crippling the spacecraft and endangering the three astronauts on board.
“Mission Control had asked for a cryo-stir in the oxygen tank …and Jack threw the switches,” Haise continued. “There was a very loud bang that echoed through the metal hull, and I could hear and see metal popping in the tunnel [between the command module and the lunar lander]… There was a lot of confusion initially because the array of warning lights that were on didn’t resemble anything we have ever thought would represent a credible failure. It wasn’t like anything we were exposed to in the simulations.”
What followed was a four-day ordeal as Haise, Jim Lovell and Jack Swigert struggled to get back to Earth, as thousands of people back on Earth worked around the clock to ensure the astronauts’ safe return.
Jerry Woodfill and Fred Haise at the 40th anniversary celebration of Apollo 13 at JSC. Image courtesy Jerry Woodfill.
In 2010, Universe Today also commemorated the Apollo 13 anniversary with a series of articles titled “13 Things That Saved Apollo 13.” We looked at 13 different items and events that helped turn the failure into success, overcoming the odds to get the crew back home. We interviewed NASA engineer Jerry Woodfill, who helped design the alarm and warning light system for the Apollo program, which Haise described above.
Now, five years later on the 45th anniversary of Apollo 13, Woodfill returns with “13 MORE Things That Saved Apollo 13.” Over the next few weeks, we’ll look at 13 additional things that helped bring the crew home safely.
Jerry Woodfill working in the Apollo Mission Evaluation Room. Credit: Jerry Woodfill.
Woodfill has worked for NASA for almost 50 years as an engineer, and is one of 27 people still remaining at Johnson Space Center who were also there for the Apollo program. In the early days of Apollo, Woodfill was the project engineer for the spacecraft switches, gauges, and display and control panels, including the command ship’s warning system.
On that night in April 1970 when the oxygen tank in Apollo 13’s command module exploded, 27-year-old Woodfill sat at his console in the Mission Evaluation Room (MER) at Johnson Space Center, monitoring the caution and warning system.
“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. “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.”
Listen to the audio of communications between the crew and Mission Control at the time of the explosion:
Located in an auxiliary building, the MER housed the engineers who were experts in the spacecrafts’ systems. Should an inexplicable glitch occur, the MER team could be consulted. And when alarms starting ringing, the MER team WAS consulted.
The Mission Evaluation Room. Credit: Jerry Woodfill.
The ebullient and endearing Woodfill brings a wealth of knowledge — as well as his love for public outreach for NASA — to everything he does. But also, for the past 45 years he has studied the Apollo 13 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 13 MORE things that saved Apollo 13, in addition to the original 13 he shared with us in 2010.
Woodfill tends to downplay both his role in Apollo 13 and the significance of the MER.
“In the MER, I was never involved or central to the main events which rescued Apollo 13,” Woodfill told Universe Today. “Our group was available 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.”
But Apollo Flight Director Gene Kranz, also speaking at the 2010 event at the Smithsonian Air and Space Museum, has never forgotten the important role the MER team played.
“The thing that was almost miraculous here [for the rescue], was I think to a great extent, the young controllers, particularly the systems guys who basically invented the discipline of what we now call systems engineering,” Kranz said. “The way these guys all learned their business, … got to know the designs, the people and the spacecraft … and they had to translate all that into useful materials that they could use on console in real time.”
Apollo 13 astronauts Fred Haise, Jim Lovell and Jack Swigert after they splashed down safely. Credit: NASA.
Join Universe Today in celebrating the 45th anniversary of Apollo 13 with Woodfill’s insights as we discuss each of the 13 additional turning points in the mission. And here’s a look back at the original “13 Things That Saved Apollo 13:
Infinite Worlds - People & Places of Space Exploration: by Michael Soluri, Foreword by John Glenn. Cover image courtesy of Michael Soluri and Simon & Schuster.
On April 24, 1990, the Hubble Space Telescope was launched from Kennedy Space Center into low Earth orbit. Hubble was the first telescope designed to operate in space, so it was able to avoid interference from Earth’s atmosphere – an inconvenience that had limited astronomers since they first looked up to the skies. However, scientists quickly realized that something was wrong; the images were blurry. Despite being among the most precisely ground instruments ever made, the primary mirror in the Hubble was about 2,200 nanometers too flat at the perimeter (for reference, the width of a typical sheet of paper is about 100,000 nanometers). Luckily, there was a solution.
Hubble was designed to be serviced in space. As NASA writes on the telescope’s website, “a series of small mirrors could be used to intercept the light reflecting off the mirror, correct for the flaw, and bounce the light to the telescope’s science instruments.” A series of five missions lasting from 1993 to 2009 was devised to correct the mirror and perform various upgrades. Despite being the first of their kind, the missions were declared a resounding success – and they enabled the Hubble Space Telescope to remain operational to this day. Many of Hubble’s images are among the most incredible ever produced by mankind, yet few people know anything about the remarkable men and women who made them possible.
ohn Grunsfeld, just before entering shuttle Atlantis for his fifth mission in space and his third to the Hubble Space Telescope. Grunsfeld wrote “Climbing Mountains” for Infinite Worlds. Credit and copyright: Michael Soluri.
Infinite Worlds: People & Places of Space Exploration, the latest book from photographer Michael Soluri, documents the people who worked on the last of these repair missions, STS-125 (also known as Hubble Space Telescope Servicing Mission 4 [HST-SM4]). The nearly two-week journey aboard Space Shuttle Atlantis saw the successful installation of two new instruments and the repair of two others. Like the four other shuttle crews that came before them, the men and women aboard STS-125 enabled Hubble to see deeper and farther into the past than ever before.
Michael Massimino, a veteran of the earlier STS-109 mission, is one of these people. Massimino and Soluri became fast friends after a chance encounter, when Soluri asked: “What is the quality of light really like in space?” Following their discussion, Massimino asked Soluri to teach him and the rest of the crew how to take photographs that would better communicate their experiences in space. Astronauts are always taking pictures, but the lighting in space is, understandably, not always ideal. Like Soluri himself in Infinite Worlds, the astronauts repairing Hubble were looking for better ways to communicate the beauty of space travel through photography.
Soluri was granted unprecedented access to document the people and events behind the mission throughout a period of more than four years. The photographs in the book “give deserved attention to a few of the many thousands of people who worked on the Space Shuttle and Hubble Space Telescope programs,” reads an inspiring foreword by John Glenn, the first American to orbit the Earth. Infinite Worlds reveals a side of space travel that most of us would never otherwise see, including the training sessions, tools, and trials that make success possible. NASA, notorious for keeping their employees tightly scripted and inaccessible, rarely grants such access – and with the closing of the Space Shuttle Program in 2011, such intimacy may never be seen again.
Jill McGuire, Manager, Hubble SM4 Crew Aids and Tools, in Mission control in Houson during EVA 4, May 2009. Credit and copyright: Michael Soluri.
Science is a cooperative discipline, but most people only ever see the results. The tireless work of thousands of individuals is often taken for granted and forgotten. Although many people still hold the false idea that scientific accomplishments are made by individual geniuses working in an armchair, now more than ever before we are entering an age where science is performed by large teams working cooperatively. To mention just one example, CERN hosts scientists of more than 100 nationalities. As Jill McGuire, a manager at Goddard Space Flight Center, writes about the field in the book, “the best way to move forward in the business was to get my hands dirty by working with the skilled machinists and technicians in the branch to learn everything I could.”
Infinite Worlds grants readers an exhilarating glimpse into this cooperative world. One particularly inspiring section follows the immediate buildup to the launch of STS-125. The transcript of the pre-launch quality check is paralleled by images of the situation as it happened. Black and white photographs from both cockpit and control room highlight the tension behind “the most risky thing NASA does,” according to Space Shuttle Launch Director Michael Leinbach. He continues, “they were real people with real families, real children, real lives.” Infinite Worlds reminds us of this: the work behind every scientific breakthrough is not magic, but rather the result of talented and dedicated individuals.
As we approach the 25th anniversary of the Hubble Space Telescope’s launch and look to the future, a book like Infinite Worlds is more relevant now than ever before. The beautiful photographs in Soluri’s book tell two kindred stories: not only the heroic report of repairing a multi-billion dollar piece of equipment, but also a unique glimpse at the inspiring men and women who made it all possible. Whether humanity’s next missions are to Mars, Europa, or elsewhere, one thing will remain constant – we will only reach the stars through the work of exceptional people.
Soluri will give a presentation and do a book signing on April 11, 2015 at the Smithsonian’s Hirshhorn Museum & Sculpture Garden. Soluri will be joined by four individuals who played key roles in Service Mission SM4: astronaut Scott Altman, the STS-125 shuttle commander; David Leckrone, senior project scientist; Christy Hansen, EVA spacewalk flight controller and astronaut instructor; and Hubble systems engineer Ed Rezac. More information on that event can be found here.
A little world is making big headlines in 2015. NASA’s Dawn spacecraft entered orbit around 1 Ceres on March 6th, 2015, gaving us the first stunning images of the ~900 kilometre diameter world. But whether you refer to Ceres as a dwarf planet, minor planet, or the king of the asteroid belt, this corner of the solar system’s terra incognita is finally open for exploration. It has been a long time coming, as Ceres has appeared as little more than a wandering, star-like dot in the telescopes of astronomers for over two centuries since discovery.
And the good news is, you can observe Ceres from your backyard if you know exactly where to look for it with binoculars or a small telescope. We’ll admit, we had an ulterior motive on pulling the trigger on this post three months prior to opposition on July 24th, as Dawn will soon be exiting its ‘shadow phase’ and start unveiling the world to us up close. The first science observations for Dawn begin in mid-April.
Ceres spends all of 2015 looping through the constellations of Capricornus, Microscopium and Sagittarius. This places it low to the south for northern hemisphere observers on April 1st in the early morning sky. Ceres will pass into the evening sky by mid-summer. Ceres orbits the Sun once every 4.6 years in a 10.6 degree inclination path relative to the ecliptic that takes it 2.6 AU to 3 AU from the Sun. The synodic period of Ceres is, on average, 467 days from one opposition to the next.
Ceres, Vesta and Mars group together in 2014. Image credit and copyright: Mary Spicer
Shining at magnitude +8, April 1st finds Ceres near the Capricornus/Sagittarius border. Ceres can reach magnitude +6.7 during a favorable opposition. Note that Ceres is currently only 20 degrees east of the position of Nova Sagittarii 2015 No. 2, currently still shining at 4th magnitude. June 29th and November 25th are also great times to hunt for Ceres in 2015 as it loops less than one degree past the 4th magnitude star Omega Capricorni.
Ceres meets up with Omega Capricorni on June 29th. Credit: Stellarium.
You can nab Ceres by carefully noting its position against the starry background from night to night, either by sketching the suspect field, or photographing the region. Fans of dwarf planets will recall that 1 Ceres and 4 Vesta fit in the same telescopic field of view last summer, and now sit 30 degrees apart. Ceres is now far below the ecliptic plane, but will resume getting occulted by the passing Moon on February 3rd, 2017.
Ceres was discovered by Giuseppe Piazzi on the first day of the 19th century on January 1st, 1801. Ceres was located on the Aries/Cetus border just seven degrees from Mars during discovery. Piazzi wasn’t even on the hunt for new worlds at the time, but was instead making careful positional measurements of stars with the 7.5 centimetre Palermo Circle transit telescope.
A 1802 publication by Piazzi describing his discovery of Ceres. Credit: Image in the Public Domain.
At the time, the discovery of Ceres was thought to provide predictive proof of the Titus-Bode law: here was a new planet, just where this arcane numerical spacing of the planets said it should be. Ceres, however, was soon joined by the likes of Juno, Pallas, Vesta and many more new worldlets, as astronomers soon came to realize that the solar system was not the neat and tidy place that it was imagined to be in the pre-telescopic era.
To date, the Titus-Bode law remains a mathematical curiosity, which fails to hold up to the discovery of brave new exoplanetary systems that we see beyond our own.
Piazzi’s 1801 log describing the motion of Ceres against the starry background. Credit: Monatliche Correspondenz
The view from Ceres itself would be a fascinating one, as an observer on the Cererian surface would be treated to recurrent solar transits of interior solar system worlds. Mercury would be the most frequent, followed by Venus, which transits the Sun as seen from Ceres 3 times in the 21st century: August 1st, 2042, November 19th, 2058 and February 13th 2068. Mars actually transits the Sun as seen from Ceres even earlier on June 9th, 2033. Curiously, we found no transits of the Earth as seen from Ceres during the current millennium from 2000 to 3000 AD!
From Ceres, Jupiter would also appear 1.5’ in diameter near opposition, as opposed to paltry maximum of 50” in size as seen from the Earth. This would be just large enough for Jupiter to exhibit a tiny disk as seen from Ceres with the unaided eye. The four major Galilean moons would be visible as well.
The mysteries of Ceres beckon. Does the world harbor cryovolcanism? Just what are those two high albedo white dots? Are there any undiscovered moons orbiting the tiny world? If a fair amount of surface ice is uncovered, Ceres may soon become a more attractive target for human exploration than Mars.
All great thoughts to ponder, as this stellar speck in the eyepiece of your backyard telescope becomes a brand new world full of exciting possibilities.
Alexei Leonov during the first ever spacewalk on March 18, 1965. 3-D anaglyph created from individual frames from the movie of the walk by Andrew Chaikin.
On March 18, 1965 Soviet cosmonaut Alexei Leonov made the first spacewalk in history, floating outside his Voskhod 2 capsule. Leonov made the walk when he was just 30 years old, and later wrote that he felt “like a seagull with its wings outstretched, soaring high above the Earth.” His spacewalk lasted just 12 minutes but that was long enough to prove that humans in space could work outside a spacecraft.
Author and space historian Andrew Chaikin created some unique 3-D views of Leonov’s spacewalk, made from individual frames from the movie of the walk. Above is a red-cyan anaglyph, but if you don’t have your 3-D glasses available, don’t worry: Chaikin has also created stereo pair 3-D images, which you can view by crossing your eyes (explanation below, if you need a little help).
Alexei Leonov during the first ever spacewalk on March 18, 1965. Cross-eyed 3-D stereo pair created from individual frames from the movie of the walk. Credit: Andrew Chaikin.
Oxford University provides this explanation of how to cross your eyes to view a stereo pair as a 3-D image:
Hold a finger a short distance in front of your eyes and stare at it. In the background you should see two copies of the stereo pair, giving four views altogether. Move your finger away from you until you see the middle two of the four images come together. You should now see just three images in the background. Try to direct your attention slowly toward the middle image without moving your eyes, and it should gradually come into focus.
Alexei Leonov during the first ever spacewalk on March 18, 1965. 3-D anaglyph created from individual frames from the movie of the walk. Credit: Andrew Chaikin.
While the spacewalk was exhilarating, getting back into the spacecraft became dicey. Leonov’s spacesuit expanded so much in the vacuum of space that he had a hard time squeezing back into the spacecraft. He took a risk and opened a valve on the suit to let enough air escape, which allowed him to enter the airlock.
Leonov’s walk took place almost 3 months before American astronaut Ed White took his spacewalk on Gemini 4. The first European to do a spacewalk was the French spationaute Jean-Loup Chrétien, who flew to the Russian Mir space station in 1988.
Alexei Leonov during the first ever spacewalk on March 18, 1965. Cross-eyed 3-D stereo pair created from individual frames from the movie of the walk. Credit: Andrew Chaikin.Alexei Leonov during the first ever spacewalk on March 18, 1965. 3-D anaglyph created from individual frames from the movie of the walk. Credit: Andrew Chaikin.
Alexei Leonov during the first ever spacewalk on March 18, 1965. Cross-eyed 3-D stereo pair created from individual frames from the movie of the walk. Credit: Andrew Chaikin.
Thanks to Andrew Chaikin for sharing these images with Universe Today.
Group photo of the first cosmonauts. Taken just after the flight of Voskhod 2 in 1965, in order of flight (from left), the first Soviet cosmonauts: Yuri Gagarin, Gherman Titov, Andrian Nikolayev, Pavel Popovich, Valeri Bykovsky, Valentina Tereshkova, Konstantin Feoktistov, Vladimir Komarov, Boris Yegorov, Pavel Belyayev and Alexei Leonov. Alexei had just returned to Earth after performing the first spacewalk in history during the Voskhod 2 mission. Credit: alldayru.com, via ESA.
Seen at the James and Barbara Moore Observatory in Punta Gorda, Florida: a scope worthy of a quasar hunt. Photo by author.
“How far can you see with that thing?”
It’s a common question overhead at many public star parties in reference to telescopes.
In the coming weeks as the Moon passes Full and moves out of the evening sky, we’d like to challenge you to hunt down a bright example of one of the most distant and exotic objects known: a quasar.
To carry out this feat, you’ll need a ‘scope with at least an aperture of 20 centimetres or greater, dark skies, and patience.
Although more than 200,000 of quasars are currently known and they’re some of the most luminous objects in the universe, they’re also tremendously distant. A very few are brighter than magnitude +14, about the brightness of Pluto. Most quasars have an absolute magnitude rivaling our Sun, though if you plopped one down 33 light years away, we’d definitely have other things to worry about. Continue reading “Peer Into the Distant Universe: How to See Quasars With Backyard Telescopes”
The world's greatest rockets, past, present and future. Credit and copyright: Alex Brown.
MOAR rockets! As a followup to our recent post about the Rockets of the World (to scale), here’s another graphic posted on imgur, created by Alex Brown. While the earlier graphic only included rockets that had flown, this one has rockets that are also in development, such as the SLS, Falcon Heavy and the Long March 9. It’s also a great look back at the history of rocket development, including the V-2 ballistic, England’s Black Arrow and Korolyov’v wide-body Sputnik. All are shown to scale, as compared with an average human being.
As noted, this graphic is as of the present, February 2015.
