Say Again Apollo 14 · Gallery of lunar exploration
← Stop 1 · The button

The button - Historical Evidence

The button - Historical Evidence

The following claims appear in stop 1, in Marion and Theo's lines or in the archive clips, and are assessed against primary and secondary sources. Numbered citations refer to the Sources list at the end of this page. Times are ground elapsed time (GET), counted from lift-off on 31 January 1971.

Marion and Theo are invented, and so is the gallery. Their story is not assessed here: only what they say about Apollo 14, and the archive recordings they listen to.

From the dialogue

Claim: Pressed during the descent, the lunar module's ABORT button calls off the landing.

Status: Confirmed

The ABORT pushbutton was one of the lunar module's pushbutton switches, which were "used to manually override or alter automatic system operation in normal or emergency situations" [5, p. 6]. Pressing it sent an abort command to the guidance computer, and the Mission Report says what that command did once the descent had begun: "the computer automatically switches to the abort programs and the lunar module is guided to an abort orbit" [1, p. 8-6]. The abort programs flew the lander back up towards orbit with the descent engine (P70) or the ascent engine (P71) [8].

Claim: The abort signal appeared although nobody had pressed the button.

Status: Confirmed

"A command to abort using the descent engine was detected at a computer input channel at 104:16:07 ... although the crew had not depressed the abort switch on the panel" [1, p. 8-6]. At that moment the computer was aligning its guidance platform (program 52), so the signal did nothing, but in the descent programs "such an electronic spook would cause an unintentional abort" [3, 301/1 and MC-305/1].

Claim: When the fault appeared, Apollo 14 was a few hours from landing.

Status: Confirmed

Flight Control saw the abort command "about 4 hours prior to scheduled powered descent initiation" [1, p. 11-1]; MIT's simulator memo also puts it "approximately 4 hours prior to PDI" [4]. From the first detection at 104:16:07 [1, p. 8-6] to the landing at 108:15:09 [1, p. 1-1] is just under four hours. Houston told the crew the abort bit was set at 104:31:02, the first clip in this stop [2, p. 340].

Claim: It was night in Houston.

Status: Confirmed

Apollo 14 lifted off at 4:03:02 pm Eastern time (21:03:02 GMT) on 31 January 1971 [1, p. 1-1], which puts the first detection at about 11:20 pm on 4 February, Houston time, and the landing at about 3:18 am on 5 February. NASA's mission commentary transcript, which heads each tape with Houston time, agrees: the first call to the crew is on a tape headed "2/4/71, 23:29 CST", and the clips at 106:23 to 106:25 on one headed "2/5/71, 1:24 CST" [3, 297/1 and 303/1]. MIT's memo, written in Cambridge, Massachusetts, puts the discovery "shortly after 12:00 midnight" [4].

Claim: The bit was cleared, and about an hour later it was back, and then back again.

Status: Confirmed

At 104:31 Houston read up a reset using the STOP and ABORT pushbuttons, and Mitchell reported "Okay. It's reset" [2, pp. 340-341]. That procedure "isolated the failure to the abort switch" [1, p. 8-6]. Seventy minutes later, at 105:41:09, Houston called: "we're showing the abort bit set again" [2, p. 347]. At 106:23:48 it was back once more: "That bit just showed up again", the second clip in this stop [2, p. 353].

Claim: Tapping the panel near the switch cleared the signal.

Status: Confirmed

At 105:46 Haise asked Mitchell to "tap on the panel around the ABORT pushbutton and see if we can shake something loose". Mitchell: "Yes, Houston, it just changed while I was tapping there." Haise: "You sure tap nicely." [2, p. 347]. The Mission Report: "each time, the command was removed by tapping on the panel near the abort switch" [1, p. 8-6], and "Recycling the switch or tapping the panel removed the signal from the computer" [1, p. 14-29].

Claim: Tapping cleared it only until it came back.

Status: Confirmed

Six minutes after "You did good work again", at 106:30:32, Haise asked: "would you try tapping the panel again? The abort bit came back" [2, p. 356]. At 107:31:08, half an hour before the descent: "the bit appeared to be set again, and we need you to rap on the panel again by the ABORT button" [2, p. 361]. Even the final fix depended on it: "this procedure is good as long as we can get by the first entry with the bit not set" (107:40:39) [2, p. 365].

Claim: Mitchell asked Houston for a fix, and Houston and MIT were working on one.

Status: Confirmed

Mitchell's question and the reply ("We're working it right now and also MIT's working it") are in the NASA transcript at 106:25:29 and 106:25:35 [2, pp. 353-354]. Twenty minutes earlier the mission commentary had told the press that MIT, "prime contractor for the Apollo guidance system, has evolved a procedure for inhibiting the abort command" [3, 301/1]. MIT's own record says five fixes "were postulated by either MIT, Cambridge, MIT, Houston or NASA, Houston", and three were tested on its lunar module simulator [4]. The Mission Report credits the procedure to "ground personnel" [1, p. 8-11].

Claim: The likely cause was a speck of metal inside a sealed switch.

Status: Confirmed, as the probable cause

"The most probable cause of the abort command was metallic contamination within the hermetically sealed abort-switch module." X-rays and dissection of similar switches "have shown metallic contamination in several switches of the size which could have caused the flight failure" [1, p. 14-29]. The switch's contacts were "individual hermetically sealed snap-switch elements" [5, p. 7]. On the night it was only a suspicion: Haise spoke of "some sort of a contamination in the ABORT switch" [2, p. 356], and when Mitchell guessed "a solder ball", Houston replied "Well, we don't know yet" [2, p. 354]. "Speck" is the script's word; the report gives no size beyond the one quoted.

Claim: The switch could not be opened or repaired in flight.

Status: ⚠️ Supported, not stated directly

The switch elements were hermetically sealed [5, p. 7][1, p. 14-29]. The crew could reach the panel, since they tapped it, but no source records any attempt or proposal to open, replace or rewire the switch. Every fix discussed that night was a set of computer entries [4][2, pp. 355-365]. "Can't" is fair shorthand for what happened, but no source says it in those words.

Claim: The fix told the computer to ignore the abort signal.

Status: Confirmed

The mission commentary described MIT's procedure as one that "in effect would tell the computer to ignore abort - or abort stage commands" [3, 301/1]. The Mission Report: the program "would have allowed the lunar module computer to ignore the abort command, had it appeared during powered descent" [1, p. 14-29], by inhibiting "the computer from checking the abort command status bit" [1, p. 8-11]. MIT's memo explains how: setting the computer's mode register to the abort program "bypassed the abort monitor as the computer would read that it was already in an abort program" [4][8]. The cost was that "the abort capability of the primary guidance system was lost", so any abort would have used the backup system [1, p. 8-11].

Claim: The fix went up by voice, a line of numbers at a time.

Status: Confirmed

The NASA voice transcript has both versions read out by the CapCom over the air-to-ground loop, one keypad entry at a time: the first from 106:34:17 ("The procedure is VERB 25 NOUN 7 ENTER; 105 ENTER; 400 ENTER; 0 ENTER"), the final one from 107:33:49, each entry introduced as "the next entry" [2, pp. 357-363]. The Mission Report says the procedure was "relayed to the crew for manual entry" [1, p. 8-11]. (Its section 11 says "uplinked" [1, p. 11-1], but the transcript shows it went up by voice.)

Claim: Every line was read back.

Status: Confirmed

Every keypad entry of both versions has a read-back by Mitchell on the transcript [2, pp. 357-364]:

Switch settings given in words were acknowledged rather than repeated (for example "Understand, Fredo", 106:38:15) [2, p. 358].

Claim: Some of the fix was written down on a page.

Status: Confirmed

Before the first read-up Mitchell asked where to write it: "Do I have enough room to write just in the space on my PDI chart?", then "The time line", and "... room on the DPS burn card, Fred. Go ahead with it" [2, p. 357]. A scan of page 5 of an Apollo 14 LM Timeline Book has "V21 N1E / 1010E / 107E" handwritten in the margin [9], which is entry 1 of the final version as read up at 107:33:49 [2, p. 362]. Whose copy the page is, and whether it flew, is not known (see stop 2).

From the archive clips

Claim: Houston spotted the abort bit first, before the crew.

Status: Confirmed

The indication "was observed by Flight Control during lunar module activation" [1, p. 11-1]; the mission commentary explained that the bit had been "telemetered to the Mission Control Center" [3, 301/1]. At 104:16:07, when it first appeared, Mitchell was talking about photographing the command module [2, p. 338]. Neither crewman mentions it before Houston's call at 104:29:57: "We'd like you to back out of that 52. We need to look at a bit here." Houston then had the crew put the bit on their display, and Mitchell replied "You read the DSKY, Houston" [2, p. 340].

Claim: Haise, 104:31:02: "Antares, Houston. What we're looking at there is the abort bit, and it looks set. And we'd like to proceed with the following to reset it." Mitchell, 104:31:13: "Okay. Give me the word."

Status: Confirmed

Both lines are word for word in the NASA voice transcript [2, p. 340] and the mission commentary transcript [3, 297/1].

Claim: Haise, 106:23:48: "Okay, Ed. That bit just showed up again. Wonder if you could try tapping the panel there by the ABORT switch again."

Status: Confirmed

Word for word in the NASA voice transcript [2, p. 353], and in the mission commentary with "I wonder" [3, 303/1].

Claim: Mitchell, 106:24:20: "Anything yet, Freddo?" Haise, 106:24:23: "Okay, Ed. You did good work again."

Status: Confirmed

Both lines are in the NASA voice transcript [2, p. 353] and the mission commentary [3, 303/1]. The NASA transcripts and the Lunar Surface Journal spell the nickname "Fredo" [2][3][6]; "Freddo" is the Flight Journal's spelling [7].

Claim: Mitchell, 106:25:29: "Hello, Tom. Do you think we're going to come up with something on this problem with the ABORT button?" Stafford, 106:25:35: "Roger. We're working it right now and also MIT's working it. Needless to say, we're busy here, but we think we got a solution."

Status: Confirmed; the speaker's name is from the Journals

Both lines are word for word in the NASA voice transcript [2, pp. 353-354]; the mission commentary has "MIT working it" [3, 303/1]. Neither NASA transcript names the CapCom. Mitchell's "Hello, Tom" and "Thank you, Tom" (106:25:58) fit Tom Stafford, Chief of the Astronaut Office, and both Journals say he sat in at the console while Haise was away [6][7].

Claim: Fred Haise was the CapCom in the other three clips.

Status: Confirmed

The mission commentary named Haise as "Capsule Communicator on the coming shift" at the shift change about three and a half hours before the first clip [3, 287/3]. He was still on that shift after the landing [3, 316/2]. Mitchell addresses the CapCom as "Fredo" in the same exchanges [2, pp. 341, 353], and both Journals give these lines to Haise [6][7].

Claim: The clips are NASA air-to-ground recordings, and their times match the transcript.

Status: ⚠️ Supported

The clips come from the Lunar Surface Journal's MP3 files (by Thomas Schwagmeier), named by the start time of each excerpt: a14a_1042957_to_1043237.mp3 (104:29:57 to 104:32:37) and a14a_1062340_to_1062559.mp3 (106:23:40 to 106:25:59) [6]. Those times, and the words heard in the clips, match the NASA voice transcript [2, pp. 340-341, 353-354]. The Journal does not say which NASA tape the files were made from.

All times on this page are on the transcript's clock, measured from the actual lift-off. Because of the 40-minute launch delay, the mission timer was moved forward in flight, and the mission commentary and the Flight Journal use the later clock, so their times run 40 min 3 s later [6][7].

Sources

  1. Apollo 14 Mission Report, MSC-04112, NASA Manned Spacecraft Center (May 1971). Text also at the Apollo Lunar Surface Journal.
  2. Apollo 14 Technical Air-to-Ground Voice Transcription, NASA Manned Spacecraft Center (1971). Pages are the transcript's printed page numbers.
  3. Apollo 14 Mission Commentary, NASA Public Affairs Office transcript (1971). Cited by tape and page.
  4. S. Drake, LM Hybrid Simulator Support of the Apollo 14 Mission, DG Memo 1702, MIT Charles Stark Draper Laboratory (17 February 1971)
  5. A. J. Farkas, Apollo Experience Report: Lunar Module Display and Control Subsystem, NASA TN D-6722 (March 1972)
  6. Eric M. Jones (ed.), "Landing at Fra Mauro", Apollo Lunar Surface Journal, with audio by Thomas Schwagmeier
  7. W. David Woods, Ben Feist, Ronald Hansen and Johannes Kemppanen, "Day 5, part 3: Troubleshooting the LM Computer", Apollo Flight Journal
  8. Paul Fjeld, "Masking the Abort Discrete", Apollo Lunar Surface Journal (2009)
  9. LM Timeline Book, page 5, annotated scan, Apollo Lunar Surface Journal