Apollo 14 Docking Ring

Milled from a solid forged block of aluminum, with twelve docking latches, it’s a marvel of precision design in the era before CAD/CAM. The darker areas are from the application of dry lubricant.

An artifact from the Future Ventures’ 🚀 Space Collection.

The Smithsonian thought this was the CM docking ring from Apollo 14 Command Module, and had paperwork to support that. I think it is the sister unit, a large structural engineering component used for ground testing to try to recreate the series of docking failures experienced early in the Apollo 14 mission with the probe that was brought back (normally the docking probe would be left behind). Hence the Apollo 14 label on the base and description at the Bonhams’ auction:

NASA’s decision to fly Apollo missions using a lunar orbit rendezvous technique required the development of a system to join, separate, then rejoin two spacecraft. This system also had to allow astronauts to move internally between the Command and Lunar Modules. The flight configuration selected was an impact system consisting of a probe located at the forward end of the Command Module (CM) and a funnel-type drogue located at the top of the Lunar Module (LM). The CM’s probe was mounted to the docking ring, which provided a point of structural integrity for the two docked vehicles once the probe was removed. Removal of the probe created a tunnel so the crew could travel between the docked vehicles. A series of latches around the docking ring locked the vehicles together. The tip of the probe had a set of three small capture latches which were designed to hold the vehicles together long enough that the larger docking ring latches could be engaged.

Just after the Saturn V’s third stage sent Apollo 14 on its planned trajectory toward the moon, Shepard along with astronauts Edgar Mitchell and Stuart Roosa experienced difficulty docking the CSM to the LM. Five attempts were made but the docking probe capture latches never engaged to secure the two vehicles together. This could have scrubbed for the second time in a row a lunar landing mission. With the failure of Apollo 13 due to a Service Module oxygen tank explosion, a scrub of the Apollo 14 lunar landing would most certainly have provided ammunition to those in Congress lobbying for an early termination of the Apollo Program.

After almost 2 hours of delays and on the sixth attempt, with Roosa holding the CSM tight with the LM for several seconds, the latches finally engaged. The crew then activated the series of larger latches mounted along the docking ring to obtain a “hard dock” configuration. Although they were finally docked, Mission Control and the crew’s concern shifted to the possibility that the system could fail when it was most needed, the redocking of the LM Ascent Stage after Shepard and Mitchell’s return from the moon. If this happened the crew could be forced into performing a space walk in order to return to the CSM. The lunar rocks and scientific data might have to be abandoned in the LM pending the exact circumstances of a potential lunar orbit docking problem. The probe was thoroughly inspected by the crew during the coast period to the moon and they sent detailed verbal descriptions plus television pictures to Mission Control. Since the probe now showed normal operation of the capture mechanism, NASA made the decision to proceed with the planned mission.

The redocking while in lunar orbit was completely normal. The docking probe (normally jettisoned with the LM) was returned to earth for inspection and analysis.

NASA and spacecraft manufacturer North American Rockwell performed an exhaustive series of tests to the docking system. All components (probe, latches, docking ring) were tested “in place” with the recovered Apollo 14 CM, then each was removed for a series of combined and individual tests. The docking system problem was a major reason the docking ring was removed and never re-installed into the Apollo 14 CM. Post-flight analysis of television, motion picture film, accelerometer information, and reaction control system thruster activity indicated that probe-to-drogue contact conditions were as expected for all docking attempts. The probe’s capture latches should have worked on each of the first five docking attempts. A plunger-type component in the capture latch failed to reach a forward or locked position most likely due to some type of foreign debris or contamination. A change in the size of the plunger due to temperature was an additional possibility. Internal damage to the capture-latch mechanism was ruled out as the cause because the system functioned properly in all subsequent operations following the sixth docking attempt and during post flight testing. The debris or contamination most likely became dislodged after the fifth docking attempt, allowing the system to operate properly from that point. NASA and Rockwell made the decision to provide a protective cover on the tip of the probe to prevent contamination during future flights.

During the tests, the ring was shipped between various NASA and contractor facilities via a 39 by 39 by 12 inch wood transit case which is included with the ring. The ring itself has a series of inspection stamps and ID numbers that read: “MDR 408699, V36-316250-9, 06361-B009522, MR 361588, DEC 9 1968, V36 316250 31, ASSEM, FEB 18 1969, 06361A015194.” A separate 6 by 3 inch yellow “Temporary Parts Removal Tag” repeats several of these numbers and has the additional hand-written information of: “TPS 112, REM #103, Docking Ring, S/C 110, 2/14/72.”

Included are copies of documents listing the NASA artifact number (2243) being from Command Module (S/C # 110) for the transfer to the National Air and Space Museum (NASM) and deascession papers from NASM.

The Apollo 14 docking ring is the single largest and heaviest piece of lunar spacecraft structural equipment ever to be offered to private hands. The flown CM docking ring, the twin of this one, remained with the ascent stage of the Lunar Module Antares when it was jettisoned. Antares was then deliberately crashed into the moon’s surface to simulate a “moonquake.”