Jim Lovell, Jack Swigert, and Fred Haise were meant to be the third Apollo crew to journey to the Moon on a lunar landing mission. On April 11, 1970, the Apollo 13 astronauts launched from Kennedy Space Center. However, disaster struck before the crew reached their destination: An explosion on one of the service module’s oxygen tanks caused damage to the spacecraft. The mission to get to the Moon quickly turned into a challenge to return safely back to Earth. Lovell, Swigert, and Haise piled into the lunar module (LM), a craft built for two, aborted the lunar landing, and began the necessary steps to return home.

While oxygen supplies were sufficient for three, the carbon dioxide produced by the astronauts exceeded the capacity of the onboard LM lithium hydroxide filters. The filters in the lunar module and the command module (CM) were not interchangeable due to differences in shape, so Mission Control engineers back in Houston had to get creative to use the CM filters with the system on the LM, using only materials the astronauts had available to them in the spacecraft.


Deke Slayton demonstrates the modified LiOH canister to Mission Control during the Apollo 13 mission. (NASA image S70-35013)

Using a clever solution of a plastic bag, cardstock, a spacesuit hose, and that stuff that holds everything together, duct tape, the engineers in Mission Control mocked up an altered lithium hydroxide filter. The astronauts then recreated the contraption (nicknamed “the mailbox”) on the LM.  It was a massive success! The mailbox successfully coupled with the LM and kept the carbon dioxide levels down for the duration of the trip. 

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Photograph of modified LiOH canister in use on the LM (NASA image AS13-62-8929)

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Photograph of Swigert and the LiOH canister on board the LM (NASA image AS12-62-9004)

To capture this great moment in NASA history, in 1975 the National Air and Space Museum commissioned a replica from the original personnel who had worked on the Apollo 13 mission.  The replica of the modified lithium hydroxide cannister is slated for display in the new Destination Moon exhibition (scheduled to open in 2022).

While this was not the original mockup created during the Apollo 13 mission (the original “mailbox” was left on the LM which was jettisoned before reentry), the artifact captures the ingenuity of the engineers and serves as an important historical “document” of the event. Therefore, like any conservation treatment, the care of the artifact was prominently at the forefront of all discussions. 

As can be imagined, such a jury-rigged piece of equipment came with its own set of conservation concerns. Gravity and time had taken its toll on this artifact. The weight of the hose combined with the failed adhesive of the duct tape caused rips in the plastic, distortions in the cardstock, misplacement of several pieces of duct tape, detachment of the hose, and deformation of the plastic bag.  Comparisons with early photographs of this artifact also revealed that the cardstock was originally more aloft and less compressed.

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Before treatment; note distortion of the plastic, the failed adhesive of the duct tape, and the adhesive residues left by the tape

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Before treatment; note adhesive residues and stressed plastic caused by the hose's weight

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Before treatment; note tears in the plastic caused by the weight of the hose

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Before treatment; note the distorted, compressed appearance of the cardstock caused by the weight of the hose

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Apollo 13 lithium hydroxide canister mockup before treatment; note that the hose is removed as it was detached from the object


The aim of the conservation treatment was to bring the object to a stable and more accurate configuration. The main concerns were the shape of the cardstock and safe reattachment of the lifting duct tape and hose. Treatment commenced after a thorough documentation and approval from the curator. Numerous steps were undertaken as part of the treatment, and I will share the most important steps below.    

Repositioning of the Cardstock

The shape of the cardstock was significantly distorted and was no longer in keeping with the intent of the engineers. To accurately represent the modified cannister used during the mission, the cardstock required reshaping. Paper artifacts are often reshaped and distortions removed through the addition of water vapor, a step referred to as “controlled humidification.” However, humidification was an unfavorable options due to the limited access to the interior and the potential to create condensation and a microclimate.  Instead, a mechanical approach was undertaken through the small access hole on the bag. Using hand tools, it was determined that the cardstock was still pliable and could be repositioned into its original orientation without stressing the paper. To provide support to the cardstock and help keep its shape, a tear drop-shaped Tyvek pillowcase was inserted underneath the cardstock and filled with archival batting. The pillow provided the cardstock much needed support and reinstated the correct configuration.


Apollo 13 lithium hydroxide canister mockup after treatment; note the pillow underneath the cardstock and the reattached hose

Duct Tape Reattachment

After the pillow support was installed, the hose was reattached. The placement of the hose was guided by early photographs of the artifact and an appropriate adhesive was selected to re-adhere the original duct tape to the plastic bag. To avoid introducing organic solvents to the aging plastic bag, an aqueous-based acrylic dispersion, Lascaux 498HV, was selected. Brush applications of the adhesive were applied to the underside of the lifted duct tape and gently held in place using weights until dry. Once the hose was reattached, it was determined that the weight of the hose still had the potential to damage the artifact over time. To prevent this, the storage mount and the display mount will support the weight of the hose. 

After the treatment was complete, the artifact was representative of what was used on the Apollo 13 mission. Come check out this amazing artifact when it goes on view in 2022!

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After treatment; note reattached hose and correctly positioned cardstock

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After treatment; note the reattachment point of the hose

Related Topics Apollo program Spacecraft Behind the scenes Technology and Engineering
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