Fifty years ago: Farewell — Apollo 17 leaves lunar orbit

Dec. 16, 1972: The moon as Apollo 17 pulls away. A slice of the backside is visible on the right.

*****

It’s the morning of Dec. 16, 1972, and wake up comes to the moon at 10:03 a.m. EST on our 71st orbit.  It’s TEI day for Apollo 17.  TransEarth Injection.  We’re coming home, and have four orbits to go after six days in lunar orbit for our command ship named America.  In about eight hours, we, Gene Cernan, Ron Evans and Jack Schmitt, will pull out of orbit — the last visitors for a long time, we know; but not too long we hope.  

We share one last meal in lunar orbit, then get to work, conducting housekeeping chores and realigning our guidance platform.  Behind us in one bay of the cylindrical Service Module, several units of the Scientific Instrument Module (SIM) continue to probe the surface below us.  Three hours before TEI, at the end of orbit 73 and start of our next-to-last orbit, 74, the SIM instruments take their last readings and photos. 

In our six days in orbit, the SIM’s panoramic camera, with a surface resolution of 3 by 6 ft., took 1,603 frames.  The mapping camera captured 3,000 images precisely locating surface features.  The laser altimeter made 3,769 readings of the lunar heights.  The infrared radiometer recorded 100 hrs. of data on surface temperatures.  The ultraviolet spectrometer took 114 of readings of surface composition.  The new Lunar Sounder, which bounced HF and VHF radio signal much like radar to probe the surface to a depth of nearly a mile, proved stubborn, however.  The signals were sent and received by two 80-ft. long antennas extended from the Service Module.  We experienced problems deploying and retracting those antennas.  Still, we captured 10 hrs. of readings from the instrument.  Ron Evans, “Captain America” conducted most of the SIM operations, and in addition made detailed visual observations, all of which will help place our exploration of the valley of Taurus Littrow in a wider context.  

On orbit 74, we complete our pre-burn checks, in our seats now, and an hour before TEI, maneuver our command ship, America, to burn attitude.  We’re approaching the western limb of the moon on our 75th and final orbit.  As when entering orbit, the burn to leave will occur while we’re on the backside of the moon, blocked from communications.  As we approach LOS — loss of signal — Capcom Gordon Fullerton calls.  “America, Houston, about 2 min. ’til LOS . . .  We just went around the room once more. Everything looks good.  Have a good burn, and we’ll see you and the TV picture as you come out on the other side.”  We plan to switch on our TV camera as soon as we come back around.

“OK, Gordie, thank you.  We’re looking forward to a good burn.  And we’ll see you coming out the other side.”

We will fire the engine 24 min. after LOS, or the computer will, under the eye of “Captain America,” Ron Evans.  The burn will last a bit less than two-and-a-half minutes.

Come on, big engine, do your thing.  Ron issues the command to Proceed and ignition.  It’s 6:35 p.m. on the East Coast of the U.S.  A good ignition.  Thrust is good.  All systems look good.  The thrust pushes us back into our couches with just one-eighth g, but after being weightless it sure feels like more.  The engine chugs along as we watch the timer.    And at 2 min. 23 sec., automatic shutdown.   Shutdown — on time.  

We on our way home.

As we emerge from behind the moon 12 min. later, I call, “Houston, do you read America?”

“That’s affirmative, America.”

“Roger, Houston.  America has found some fair winds and following seas, and we’re on our way home.”

I tell Mission Control, “I know there’s not as many smiling faces up here as there are down there, but we’re making up for the difference . . .”

Within minutes, we turn on our TV camera and train it on the moon.  Already our landing site is shrinking from view.  As we climb away, our camera shows the complete disk, nearly a full moon.   Portions of the backside are visible along one limb, including a striking view of the crater Tsiolkovsky with it’s dark mare floor.  Both the Sea of Tranquility and the Sea of Serenity, the sites of the first and last Apollo landings, stand out. 

The brief Moon Age of Apollo, which began four years ago, almost exactly, with Apollo 8, is over.  “We’re looking back at some place, I think, we will use as a stepping stone to go beyond someday,” I say.  “. . . And I think we’ll see it in our lifetime, not just as a nation, but as a world.”

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