Fifty years ago: The last Apollo lands on the moon

Challenger on the moon: The Apollo 17 landed on the moon at Taurus-Littrow on Dec. 11, 1972, for a 75-hr. stay.

***

It’s the big day, descent to the lunar surface at Taurus-Littrow, a valley deeper than the Grand Canyon.  And it’s gonna be a long day, because after landing you and I are going to conduct our first of three moonwalks.  We suit up 6 hrs. before landing time and enter our LM, Challenger.   It’s 9:50 a.m. EST., December 11, 1972.  

Two hours before descent, we pass over the landing site.  We see it clearly.  You call out the craters in the valley. 

After thorough checks, we cut loose from our command ship, America, with Ron Evans.  He looks us over.  “OK, Houston.  This is America.  We’re floating free out here.  The Challenger looks real pretty.”

I say, “We’re looking at America the beautiful.”

It’s time for Ron to take America into a higher orbit where he won’t just await our return, but maintain a busy schedule scanning wide swaths of the lunar surface with an array of instruments.  The burn marks the point where things went wrong on Apollo 16.   This time the vital Service Propulsion System engine, the same one that got us into lunar orbit and must take us out again, checks out perfectly.  At 1:21 p.m., Ron fires it for just 3.8 sec., enough to lift him into a circular orbit.  Five minutes later, we lower our orbit by 8 mi., setting up the landing on the next orbit. 

We’re in the silence behind the moon for the last time before landing.  As we come around back into communications, Houston will only have 15 min. to check out our systems one final time.  That’s because we’re landing relatively close to the eastern edge of visible face of the moon.

We’re back in range, everything moving fast now.  Everything is looking good.

“One minute, Houston, and we’re standing by.  We’re go for PDI.”  Powered Descent Initiation, the start of our 12-min. descent to the surface.  We’re flying with the Descent Propulsion System (DPS) engine pointed forward, and we’re looking down at the road behind us.

The capcom says, “Roger, you’re looking good here.”  This landing will push the Lunar Module to the very edge of its performance capabilities.

We tell the computer to proceed.  Ullage.  That’s a 10-sec. burst from our Reaction Control System (RCS) jets to settle the propellants in their tanks.  “We’ve got ullage.”  And . . . “Ignition.”

“Ignition, Houston.  Attitude looks good.”  We start with the engine at low thrust.

But damn at ignition, an indicator flashes.  “Descent Quantity Light” — which would say that our fuel supply is low.  Is something wrong?  Or is the indicator at fault?

After 20 sec., the engine ramps to full thrust.  “Throttle-up’s on time.”

What about that fuel indicator?  “Still got that Quantity Light,” I tell Houston . . .

Approaching 2 min. into the burn.  Houston finally says something about that light.  “We’d like you to cycle the PQGS switch off and then back on.”  That’s the Propellant Quantity Gauging System.

“OK  It’s off.  And it’s back on.  Quantity light is out.”  So it was just a glitch in the indicator.

Everything now looking good.  We tell capcom Gordon Fullerton, “OK, Gordo.  Coming up on 3 min., we’re go.”

Spacecraft attitudes are good, RCS is good, everything is right on.  We’re a bit high, but the computer is taking the excess altitude out as we descend.

“Challenger, Houston.  You’re go at 4 min.”

We now yaw — slowly rotate — so that we are facing the darkness of space.  This position allow the radar at the bottom of the descent stage to sound the surface. 

The radar immediately locks on the surface, the event signaled when two radar warning lights blink off.  I call “And the radar lights are off.  Beautiful.”

And even more beautiful, “We’ve got the Earth right out the front window.”  

. . . Five minutes into the burn.  We’re 53 mi. from the landing site.  For most of the descent, you, Jack, have to keep your eyes inside the cockpit, reading out the displays.  Indeed, you will later joke that you missed it all.  Right now, I tell you, “You’re allowed two quick looks out the window, one now and one when we pitchover.” — that’s when we see the landing site.

“I can’t see anything except the Earth.”

“That’s what I’m telling you to look at.”

You laugh, “Oh!”

. . . Now 40 mi. from the landing site, coming over the mountains, 20,000-ft.-tall peaks.  We’re at 31,000 ft., a tight margin.  We can see when we pass them in the radar readings . . .  I report to Houston that we saw it “as we went over the hump.”

I say, “It looks good, babe.”

Yaw complete — we’re windows up, now more than half through the descent.  Houston calls, “Throttle down time — 7 plus 26.”   We’ll ease back on the thrust at 7 min. 26 sec. into the descent.  Here it comes.

“Throttle down.”

“Beautiful,” you say.  We’re right where we want to be, altitude and distance.

Eight minutes, and I urge, “Come on, baby.”  We’re starting to tilt toward the vertical.  By peeking over the bottom of my window, I see it!  I see it — I see South Massif mountain slide into view — it’ll be the goal of our second moonwalk, where we’ll seek to sample boulders from the early lunar crust.  Babe, it sure seems like were flying formation with the mountain peaks that surround our valley of Taurus-Littrow!

. . . Nine minutes.  “OK, stand by for pitchover,” 

Pitchover!  “There it is.” We’re at 7,000 ft. altitude and 3 mi. from the landing site.  It’s right in front of us.  “There’s Camelot.”  That’s a big crater on the valley floor, a good marker.  “Right on target,” I say.   We can see all the craters we’ve memorized and named, there on the dark valley floor, which we hope is volcanic.  We’ll sample it on a short traverse on our first moonwalk.  Its surface sure looks dark compared to the bright mountains ringing it.

But damn, there are more boulders and small craters down there than I expected.  If we have to abort, we’ll need to fly over the 7,000-ft-tall Family mountain to the west.  That’s be tight — we’d really have haul mail. 

Now that we’ve cleared the mountains, we’re coming down in a steep descent.   Houston calls, “Challenger, you’re go for landing.”   We’re at 800 ft.   Coming down fast — I can control it — and the steep descent will save fuel.  I don’t need the computer targeting anymore.   I need to avoid a big block out there, but if I go too far, I know there’s a rough, blocky area beyond.  We pass 300 ft. altitude, 10 min. into the descent.  I take over full manual control.  I want some forward velocity to avoid any tendency to drift backwards. 

“Moving forward a little,” you say, reading the instruments.   Sixty feet up — you glance out and say, “Getting a little dust.”

We’re in the “dead man zone” now.  Within 200 ft. of the surface, if we tried to abort, we’d crash before our ascent engine could catch altitude.

I watch our shadow, a tiny bug at first, grow and approach.  I gauge that when we merge with our shadow, we’ll have landed.  And it’s coming fast now, growing in size.  “Stand by for touchdown.”

You see the blue light come on, signaling the the probes at the bottom of the landing gear have touched the surface.  “Contact,” you call.

I cut the engine and we fall the final few feet with a thud.

Silence.  We’re down, 2:54 p.m. EST, December 11, 1972.  Silence, everything stops.  For a moment.  Then we work, checking the systems, configuring them for the stay.  Yet still we can’t hold back our excitement.

“OK, Houston.  The Challenger has landed.”

“Roger, Challenger.  That’s super.”

“You bet it is.”   

I turn to you and exclaim, “I shut down and we dropped, didn’t we?”

“Yes, sir –but we is here!”

“Man, is we here!”

Busy checking Challenger, yes, but we can’t help but take an eye to the window and survey the scene.  “Jack, are we going to have some nice boulders in this area.”

You yell with enthusiasm, “Oh, man!  Look at that rock out there.”  Looking up at the mountain slopes, you exclaim, “Hey!  You can the boulder tracks.”

We landed with 117 sec. of propellant left.  “Look at all that propellant.”  

We could have hovered, taken a good look all around our valley, you say.  

“No thank you.  I like you right where we are.”  And where we are is just 200 ft. from the planned landing spot.

I look out and say, “Epic moment of my life.”   And it’s only just begun.

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