TLI: First launch to the moon

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Fifty years ago this morning, December 21 . . .

 

It begins as the faint gurgle and hydraulic hum, the first flush of fuel being fed toward the five massive F-1 engines 320 feet below us.  We are strapped in the Command Module of the Apollo 8.   At T-minus 8.9 seconds.  Ignition sequence start

Ignition.

And our first stage engines begin coming up to thrust.  A noise, not loud — the rumble of a distance storm.  No vibration, the noise increasing like the approach of a tornado.  Closer and closer, rising up the rocket.

Liftoff.  Liftoff at 7:51 a.m.

With a slight jolt.  Our commander, Frank Borman, in the left seat, acknowledges, “Liftoff, and the clock has started.”  The same call has signaled the start of every U.S. flight since Al Shepard uttered it in 1961, part of the poetry of spaceflight.  Liftoff, the rocket straining against it’s own weight, just enough thrust to overcome it, balanced a few inches above the launch platform, a few feet, a few feet further.  Rising, leaning away from the tower, engines steering back and forth to maintain balance, whipping us side-to-side.   We cannot hear each other for the roar.

Tower clear.

Gaining speed   In just 40 seconds, going supersonic, and suddenly quiet, the cacophony of the engines left behind, the only sound the hum of the electronics.  As the acceleration increases, the G-forces increase.  Until they reach 4.5 Gs.  At that point 2 min. 33.82 sec. into the flight, the first stage burns out.  Suddenly released from the G load, we are tossed forward against our tight straps.

Second stage ignition.  We are thrown back into our couches, little more than rag dolls.  We climb the steps towards earth orbit.  Second stage cutoff at 8 min. 44.04 sec.   Third stage ignition, burning just part of it’s fuel, as it will stay with us to kick up to the moon.  And shutdown — the 11 min. 34.98 sec. climb is over.  We are weightless.  We are in low Earth orbit, a familiar place, the sixteenth U.S. mission to reach it.  Soon we will leave the familiar far behind.

*

*

For nearly two orbits, we have little time to take in the view out the window.  Eyes on instruments, we check out every system of our spacecraft.  Controllers in Houston are doing the same.

At 1 hr. 56 min. into the flight, we receive a call from Capcom Mike Collins, an astronaut once assigned to this mission.  It’s not just a call but the words, prosaic to some, are more than that.

Apollo 8, you are go for TLI.

TLI — Translunar Insertion, meaning you are go for the burn that will send the first humans out of low earth orbit.  And to the moon.

TLI — three letters that speak magic, hold a poetry of their own.

That is, if the single third-stage engine actually restarts, which it failed to do on the last unmanned test of the Saturn V.

Over the Pacific, at 2 hrs. 50 min. 37.79 sec, the firing command is issued.  We have ignition, full thrust of 232,000 lbs.  We burn the engine for 5 min. 5 sec., ramping us to a velocity of 23,226 mph.

Shutdown.  On time.

We are headed toward a rendezvous with the moon.  Three hours after TLI, we will be 26,000 miles from Earth.  And the earth will be round and whole and blue.

The voice Chris Kraft, the legendary first NASA flight director, now director of the Houston space center, who rarely — if ever — speaks directly to a crew in flight, is heard over the com loop.  “You’re on your way.  You’re really on your way!”

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