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Apollo 11 LEC used as a Safety Tether

Copyright © 2004 by Eric M. Jones.
All rights reserved.
Last revised 14 January 2016.
Mark Gray, Andrew Chaikin, Ken Glover, and Ulrich Lotzmann contributed to this discussion.


In November 2004, Journal Contributor Mark Gray called attention to the fact that, during the climb down the LM ladder and during his first moments after stepping off the footpad, Neil was tethered. My first thought was that Mark was mistaken; but, during e-mail discussion with Mark and others via e-mail, a body of confirming evidence grew quickly over a few days. Mark was right. Here is what we found.

A postflight report by the MSC Crew Systems Divison (CSD) on the performance of equipment it supplied for the mission, the Lunar Equipment Conveyor (LEC) is listed as 'LEC - Waist Tether Kit'.

The Apollo 11 Final Lunar Surface Operation Plan contains several references to use of the LEC as a 'safety tether', particularly the two extracts that follow:

Ops Plan Extract
'Use of the Lunar Equipment Conveyor' (p. 26)


Ops Plan Extract
Nominal Timeline (p. 31)

The nominal timeline does not include any reference to Buzz using the LEC as a tether during his climb down the ladder, nor to its use by either crewman for the climb back up to the cabin at the end of the EVA. It seems likely that, based on pre-flight simulations, they were confident that, once Neil demonstrated that the ladder was not going to be a problem, a safety tether would no longer be necessary for this aspect of the mission.

How the LEC was Attached to Neil's Suit

The space suits worn by the lunar surface crews had a 'neckring tiedown strap' with one end fixed to the suit at chest height. In a detail from Apollo 11 training photo KSC-69P-578, Neil's tiedown strap is hanging down in front of him.

Neil's tiedown strap
Neil's tiedown strap without a snap hook (KSC-69P-578)

On Apollo 11 - but not any of the other missions - the LM crew attached snap hooks (aka 'snap locks' or, simply, 'hooks') to their tiedown straps. Buzz's can be seen in a detail from training photo KSC-69PC-362.

Buzz's Snap Hook
Snap hook attached to Buzz's tiedown strap and to the camera handle (KSC-69PC-362)

and, also, in a detail from lunar surface photo AS11-40- 5873.

snap hook
Buzz's snap hook on the Moon (AS11-40-5873)

Neil's hook can be seen in a detail from training photo 69-H-669.

Neil's Hook
Neil's hook on his tiedown strap (69-H-669)

and, as noted by Andy Chaikin, in frames from the Apollo 11 TV at the time Neil was moving the TV away from the LM.

Neil's snap on the
Neil's snap hook on the Moon (TV frame)

These hooks seem to have been intended to secure gear, as illustrated in KSC-69PC-362 (above) where Buzz has the hook fixed to the camera handle. Indeed, there are a number of training photos showing either Neil or Buzz with the hook attached to the camera handle but none indicating use with other pieces of equipment other than the camera or the LEC (below).

Neil and Buzz attached the hooks to their tiedown straps early in the EVA preparations, as per LM Lunar Surface Checklist page Sur-26. After configuring the 16-mm Data Acquisition Camera and the 60-mm and 80-mm Hasselblads, the next task was:

checklist page Sur-26 detail
Detail from Sur-26; 'hks' = 'hooks' = 'snap hooks

A discussion and pre-flight, pre-stowage photos of the package containing the Lunar Equipment Conveyor and Waist Tether is linked here. Note that the two Waist Tethers packaged with the LEC were not used in the context of Neil's ladder descent. The Waist Tethers are discussed on a separate page. Of relevance to the ladder descent are the two snap hooks, one stowed upright at each end of the bag in photo S69-37998, which they removed from the LEC/TTHR package and attached to the tiedown straps. All of this was done at some point between 106:11:14, when Neil reported that they were starting the EVA Preps, and 106:49:07, when Buzz reported they had reached the top of page Sur-27.

To complete this set of tasks, they

checklist page Sur-26 detail
Detail from Sur-26; 'hks' = LEC hooks

The PLSS Upper Donning Station Pin, known also as a 'handhold' on later missions, was inset in the cabin ceiling and is the yellow rod in Apollo 15 pre-flight photo S71-40733. In this case, the 'hooks' to be attached to the 60mm Hasselblad are the snap hooks on either end of the LEC strap, as shown in a labeled version of S69-37994.

Flown LEC
Flown LEC prepared for packaging

After donning the PLSSs, completing other EVA Prep tasks, depressurizing the cabin, and opening the hatch, at 109:15:55 they attached the hook on Neil's tiedown strap to the LEC.

Down the Ladder

With Neil's tie-down hook hooked to the LEC, they were ready for the following:

checklist page Sur-26 detail
Ops Plan extract (p. 40)

As indicated previously, Buzz would continue to play out the LEC and monitor Neil's descent and first steps on the surface.

We don't have any pictures of the LEC in use as a tether during most of Neil's climb down the ladder because the settings Buzz had on the window-mounted 16mm camera were not appropriate to shadow photography. However, just before Neil's statement at 109:24:14 that he was about the step off the footpad, Buzz changed the camera settings. The filmed image brightens and we get quite a bit of detail, including the LEC. We can also see reflections of what appear to be parts of Buzz's suit as he monitors Neil's activities out the window. Ken Glover has grabbed a frame from the 16-mm film.

Neil on the footpad
Neil about to step off the footpad

Note that there isn't much sag in the LEC, which suggests that Buzz is playing out just enough of the LEC to give Neil freedom of movement and is ready to help Neil brake any slip or fall as implied by the phrase 'use as a safety tether' in the Ops Plan. Unfortunately, we have been unable to confirm this supposition with either Neil or Buzz. In a 14 December 2004 e-mail, Neil wrote "You make a persuasive case about the LEC, but I cannot remember the detail well enough to confirm or dissent."

Training photo S69-32246 shows Neil on the footpad with his tiedown hook attached to the LEC 'end loop'. The LEC is hanging loosely on the ladder, undoubtedly because there is no one in the simulator cabin. Ulli Lotzmann notes that in, the film record of what was probably a typical training session for his first few minutes on the surface, Neil gets ready by stepping into the footpad and attaching his tiedown hook to the 'end loop'. Neil then steps off the footpad and the training session proceeds onward from that point in the timeline.

Neil on the footpad
Neil during training, about to step off the footpad with his tiedown hook attached to the LEC.

Returning to the actual mission, once Neil is on the footpad and the TV signal switches to Honeysuckle at about 109:23:48, the LEC can be seen very faintly against the black sky and, as in the 16mm record, does not appear to be sagging. The LEC also becomes evident against the sunlight lunar surface once Neil is off the footpad. Andrew Chaikin has captured three TV frames

TV frames
Click on the image for a 0.8Mb version

which show the LEC, the tiedown hook, and the end loop. If my interpretation is correct, he had the tiedown hook attached to the LEC strap just above the end loop, rather than to the end loop, itself, a trivial detail.

After finishing his brief period of Environmental Familiarization, at about 109:26:16 Neil detaches the LEC from the tiedown hook and gets ready to transfer the Hasselblad camera down from the camera.

Finally, Ulli Lotzmann notes that, for Apollo 12 and the later missions, the LEC was used solely for equipment transfer, as implied by the following extract from page 31 of the Apollo 12 Final Lunar Surface Procedures volume.

Apollo 12 Lunar Surface Procedures

Early Use of the Snap Hook

In December 2005, Andrew Chaikin called attention to films clips from April 1968 underwater LM-ingress training sessions showing Al Bean using a hook and tether. Bean was the Apollo 9 back-up LMP and use of the tether and hook was undoubtedly being tested for the EVA that Rusty Schweikart performed on that mission. Use of a hook and tether on Apollo 11 may have derived from this prior use. Chaikin provided the following frames - captured from a DVD published by Apogee Books to accompany their Apollo Spacecraft (LM) News Reference Book - and captions. Additional use of the tether and hook during underwater training for Apollo 9 can be found on the DVD set for that mission

Mattingly shows
          snap hook to Bean

While Al Bean is suiting up, TK Mattingly shows him the hook and explains its use.

Mattingly shows
          snap hook to Schweikart

Mattingly demonstrates the hook to Rusty Schweickart, who observed the run in scuba gear.

Hook attached
          to porch handrail

Bean is attached to the righthand porch handrail with the tether and hook.

Close-up of
          hook attached to handrail

Close-up of the hook attached to the porch handrail.

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