50 years ago: Triggered lightning

Apollo 12’s lightning bolt strikes the launch tower

*

            We’re going to the moon again.  

                                  We, the crew of Apollo 12.  

                                              We’re going to the moon — maybe.

              We’re heading for the Ocean of Storms

                           Unfortunately, we begin our voyage

                                                    through an Earthly storm.

            Thirty-six seconds after liftoff of Apollo 12, the second moon-landing mission, shaking off raindrops like a retriever splashing out of a river, not ten seconds since our commander, Pete Conrad, radioed, “It’s a lovely liftoff,” at an altitude of 6,000 ft., a flash, a burst of static.  Pete exclaims:

            “What the hell was that?

                          I lost a whole bunch of stuff.”

            The Master alarm gives a klaxon call, the caution and warning display lights up.   With a pilot’s preciseness and a poet’s cadence, Conrad reports:

            I’ve got three fuel cell lights,

            an AC bus light,

            a fuel cell disconnect,

            AC bus overload, 1 and 2,

            Main Bus A and B out.

            It wasn’t supposed to be this way, not with the President of the United States in attendance for the launch.  Just three days before the November 14, 1969, launch date, the weather forecast was good — temperatures on the cool side and skies partly cloudy.  But no rain.

            By the day before launch, the forecast had changed thanks to the approach of a front.   A race began between the arrival of the front and the launch, set for 11:22 a.m. EST.  If we couldn’t get off by 3:50 p.m., we’d have to wait until the moon, sun and Earth were in proper position for the landing in the moon’s Ocean of Storms. That wouldn’t be until December 14.

            At 8:55, when Conrad becomes the first of us to enter the Command Module, rain is falling.  He can see it trickling against his window where it had leaked through a seam in the boost protective cover.  But there are intermittent periods where the sky lifts and the rain stops.  For launch, cloud ceilings just needed to be above 500 ft. for visual tracking of the crucial seconds after liftoff.    

            At T- 20 minutes, the weather is no-go.  The final weather call is delayed until T – 10.  A couple minutes before that mark, Launch Control declares weather a go. Ceilings acceptable, no lightning within nineteen miles.   Yet at the viewing stands three miles from the pad, rain is still falling.

*

            I’ve got three fuel cell lights,

            an AC bus light,

            a fuel cell disconnect,

            AC bus overload, 1 and 2,

            Main Bus A and B out.

            The Saturn V disappears into the clouds 23 seconds after liftoff, by the calculations of CBS’s Walter Cronkite.   But, “It was a lovely liftoff.”   The sky is getting lighter through Conrad’s window.  We’re on our way.  

            The Saturn V completes its roll program 32.3 seconds after liftoff.  Then 4.2 seconds later, Pete Conrad sees a flash, and we all hear a burst of static.

            Still, the first stage of the Saturn V plows on, directed by a mind of it’s own contained in the ring-like Instrument Unit, atop the third stage.   No one has ever seen so many lights flash at one time, at least fifteen of them flashing in the caution and warning display, top center of control panel #2 in front of the middle seat. 

            Then at 52 seconds into the flight, sixteen seconds after the first, another burst of static and the rest of the electric system — the guidance platform — goes haywire, the “eight-ball” attitude display tumbles.   “I just lost the platform,” Conrad calls,

            “OK, we just lost the platform, gang.

                              We had everything in the world drop out. “

            Yet, the Saturn V trucks along, unaffected.  As long as we’re flying true, best not to do anything rash — ride it out and hope we don’t reach orbit with a dead spacecraft.  

            Conrad says, “I’m not sure we didn’t get hit by lightning.”

                            And twice.

                                   Proving lighting can strike twice. 

*

            I’ve got three fuel cell lights,

            an AC bus light,

            a fuel cell disconnect,

            AC bus overload, 1 and 2,

            Main Bus A and B out.

            In Mission Control EECOM John Aaron, seated in the center of the second row of consoles, looked at the numbers on his screen flash in a garbled pattern, but one he’d seen before during a test when power was accidentally cut to the command module. The test had bugged him enough find a way to restore systems.   He knows what to do. “Flight, try SCE to AUX.”

            Gerry Griffin, serving as Flight Director for the first time, doesn’t know what the SCE, but passes it on.

            Capcom Jerry Carr doesn’t know what the SCE was, but passes it on to the crew.

            Pete Conrad doesn’t know what it was, indeed, replied, “FCE to AUX?”

            “SCE,” Carr corrects.  “SCE to AUX.”

            What the hell is that? Conrad wonders to the crew.

            Pilot Alan Bean knows. There, at the bottom of panel 3 in front of him, the Signal Conditioning Equipment switch.

            SCE to AUX.  And the Command Module comes back to life.

            Although work remains to reset the fuel cells, realign the guidance, check every system to make sure there hadn’t been any damage, we’re once more go for the moon.   It was a close call — created by something unconsidered by the makers of the launch rules (until it happened) — that a rocket creates an ionized trail behind it that can trigger lightning.

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