Apollo 13 Rescue Exercise
Requires Adult Supervision
“Making a Square Peg Fit into a Round
Hole”
By Jerry Woodfill
Apollo 13 Warning System Engineer
The Testimony:
For the Apollo 13 crew, the dilemma was that the square command ship’s CO2 filters would not fit into the round rescue ship’s filter barrel. These had to work to clean the cabin atmosphere of Carbon Dioxide gas. The lander’s round filters were two in number. Each had a life of approximately 24 hours with two men on board. Since there were now three men, that life would be somewhat shortened. The round filters were housed in two separate barrels in the lander. One barrel was plumbed into the cabin’s environmental control system. The other barrel simply stowed the second cartridge. When the first filter was consumed, the crew simply interchanged the filters in the barrels.
At the appointed time of Congress’s prayer edict, the first round filter would need to be changed based on the 24 hour criteria. This would leave only 24 hours to deal with the challenge and solve the problem of “making a square peg fit into a round hole.” Unfortunately, three more days journey would be needed at that time to bring Apollo 13 home. This would be at least 48 hours short of the lander’s filters’ capacity.
My recollection of the threat, besides the earlier meeting with Don Arabian, was Don’s voice bellowing from his throne in the mission evaluation room that Tuesday, “I need those guys to come up with an answer on the CO2 thing!” He was referring to the “tiger team” led by Ed Smylie, the crew systems manager working the problem. But, at 9:08 PM, April 14, 1970, an explosion of prayer stormed heaven in behalf of Apollo 13. These intercessions had been requested earlier that day by the a proclamation of the United State Congress.
Several
years later, I was speaking to a group of Christians in a small
I
responded, “What you remember is exactly
what we faced that evening…it had to do with a square ‘pig’ filter not fitting into a round barrel. Our engineers were your farmers, those pigs
were the square command ship’s carbon dioxide filters, and the barrel would be
the cylinder containing the round CO2 filters in the rescue ship.” I
believe Congress’ proclamation led to such a “vision” and prayer. The team benefited from that prayer. In a back room at the
The
Bible speaks of God knowing the number of hairs on our heads. The average number of hair follicles at any
one time on a person is 100,000. Each hair follicles can grow about 20 hairs in
a person’s lifetime. So God knows about
2,000,000 of our hairs. Now the number of parts in the command module
was about 2,000,000. Isn’t it reasonable
to conclude that God knows each of those parts as well as our hairs. But He
cares much more about the men on board than their hair so that He can impart
While the nation prayed, Smylie and his team conceived a configuration that might be successful. The concept seemed to evolve as all looked on. It was to attach a suit hose into a port which blew air through the hose into an astronaut’s space suit. If the space suit was eliminated and, instead, the output of the hose somehow attached to the square filter, perhaps, the crew could be saved. This, in effect, would bypass the barrel. The air blown through the filter by the suit fan would have no carbon dioxide as it reentered the cabin atmosphere.
The challenge was attaching the hose into a funnel-like device having a small round inlet hole for the suit hose and a much larger square outlet attached and surrounding the square filter. But the funnel would most likely leak. Added to that difficulty was the hose and plastic Moon bags tended to collapse restricting the air flow through the filter. The thought came, “Use cardboard log book covers to support the plastic.” It worked! But more importantly, “How could the funnel be fashioned to prevent leaking?” Of course…the solution to every conceivable knotty problem has got to be…DUCT TAPE! And so it was. Someone, providentially, had stowed the miracle substance onboard.
Using the plastic Moon rock bags, cardboard, suit hoses, and duct tape, the device was attached to that filter. Soon the CO2 levels had descended to safe levels. God had made a way of fitting a square peg into a round hole because the nation prayed that Tuesday evening in April of 1970. When the Master Engineer of the Universe, the Lord Jesus Christ, was called as a problem solver, He never fails. Having read my account, try the exercise described below. Of course, it would be good to pray first for God’s help. In this way, you will understand how very helpful He was to save our astronauts that week in April of 1970.
* * * * * * * * * *
Apollo 13 Rescue Exercise
Requires Adult Supervision
“Making a Square Peg Fit into a Round
Hole”
Materials: Roll of 1 inch wide masking tape, Hair Blower, Plastic Turkey Oven Bags,
8 ½” by 11” card stock, cloth fabric, roll of garden weed mesh, discarded shoe (or any other similar) box, discarded garden hose, scissors. All the items (except for garden mesh, hose and box) are likely available at a hardware or grocery store. Hand held hair dryers are always available at home.
Left Photo of First Built Version of Filter, Right Photo is Astronaut upgrade
Instructions:
- Examine the above photos for clues about fashioning your version of the Apollo 13 “jury-rig” filter from the list of materials.
- Read the air-ground instructions given the Apollo 13 astronauts for added information about making your filter. They are listed below.
- Using the instructions, pictures, and materials build a square filter with a configuration which plumbs air from the blow dryer through the hose and ultimately the filter without leaking.
DANGER: BE CAREFUL
- ATTENTION: Be sure to select the warm rather than hot setting for the blower when you switch on the hair dryer. Use your hand to test whether your design and finished approach is “air-tight”.
- Examine the photos above. What improvement is evident in the photo at the right of the improved version made by the Apollo 13 crew? The left photo shows the original version built by the crew from the instructions radioed by mission control, then constructed by the astronauts.
For the Instructor:
The sides of the shoe (or similar) box serve as the frame/structure of the filter. Cut out the center bottom of the show box after removing the shoe box lid. Cut the plastic weed screen to cover the top open end of the shoe box, then attach the mesh using masking tape around the top of the shoe box holding the mesh taunt and taping the mesh to the sides of the box as you might wrap a gift. [The mesh serves as the filtering material. Explain to the students the principle involved, i.e., having contaminated air pass through the fine mesh as though it is LiOH crystals for removing CO2 from the cabin atmosphere. Explain the purpose of the blower being a substitute for the Apollo 13 suit fan.]
Have the students construct both the square filter as well as the modified apparatus. Their device would have enabled the Apollo 13 crew to avoid using the round lander filters in the barrel-like containers shown in the above right photo.
Also, have the students fashion the means for conducting the dryer’s air flow through the garden hose into their filter system. [Prior to class, you will need to cut the garden hose into one – two foot lengths.] Note the version the ground controllers built and the later improved version built by the Apollo 13 astronauts differ. Likewise, will student’s designs and finished products differ. Have a selected team of students evaluate the completed devices and give reasons for strengths and weaknesses of each.
Lastly: Simply provide this description of the
activity to the students and have them draw, explain, or write a narrative
description of how to build their square filter apparatus without actually
constructing it. Let them pretend they
are mission control instructing the Apollo 13 crew via radio in a step-by-step
procedures how it is done. Then, ask a separate team of students to copy down
the instructions and attempt to assemble (draw) the filter as did the Apollo 13
astronauts without having a picture or photo of it. (This is certainly the least involved of the approaches. No materials required other than imagination
and ingenuity.)
* * * * * * * * * *
The educational activity supporting the above exercise follows. It is simply a close approximation of the
air-to-ground procedures called up to the crew in April of 1970. It was created
from the original Apollo 13 radio communication for a college class assignment
in Communications by George Wilson, COMM
4120, Assignment #3, 13 May 2004. This was an exercise in communicating
Instructions and Procedures.
Adaptation Procedure
for
Environmental System CO2 Filters
in
Apollo 13 Lunar Module
INTRODUCTION
This procedure, which takes approximately one hour to complete, will allow the fitting of a square Odyssey Command Module (CM) scrubber filter through the Aquarius Lunar Module’s (LM) round mounted filtration hole and will modify the Environmental Systems scrubber unit. The material is for astronauts to use when CO2 scrubbers fail in the CM, all CM filters are used or in other situations where additional scrubbing of CO2 is required. Crew Systems Division assembled and tested this information.
REQUIRED EQUIPMENT
and MATERIALS
All required equipment is contained onboard within the Apollo 13 CM and LM.
Cover to the Apollo 13 flight plan (to cover and protect the hose entry)
2 lithium-hydroxide canisters
Roll of gray duct tape
2 LCG bags
2 hoses from the red suits
2 socks
1 bungee cord (to secure the
modified filtration device to the wall of the LM)
PROCEEDURE - 19
steps
#1) Place the LCG
bag over the top of the square lithium-hydroxide canister. The bag must be pulled down to just over the triangular
ventilator slots on the side.
NOTE: Be
careful not to rip the bag because there are only three bags onboard.
#2) Tear the duct tape down the middle lengthwise to double
the linear length.
#3) Seal the bag
to the square canister by wrapping the
duct tape around the canister where the bag opening is.
NOTE: The tape must seal the opening
to prevent leakage of air flow.
#4) Poke or cut a
hole in the middle of the top of the covering bag approximately the diameter of the hose from the red suit.
#5) Insert the
hose into the hole. Secure the hose
connection into the LCG bag with duct tape.
NOTE: The tape must seal the opening
to prevent leakage of air flow.
#6) Cover the top
of the LCG bag and hose attachment with the flight plan cover in an arch. The hose will stick out of one side of the
arch.
#7) Attach the two
sides of the cardboard flight plan cover
that make contact with the square filter using a six inch long piece of duct
tape over the top. This will prevent crushing the hose and air entry on the final
mounting in step #19.
#8) Wrap the
entire top sides of the filter cube with a three foot (about an arms length) piece
of duct tape. Repeat wrapping on the
bottom of the sides of the cube.
NOTE: The tape must seal the opening
to prevent leakage of air flow.
