40 years ago: Columbia lands

April 14, 1981: touchdown!

*

*

            Landing day, April 14, 1981.  We wake a half hour early and begin our day even before Mission Control blasts their wake-up music.

            The noisy teleprinter in the lower level, the “Middeck” is clattering away with a long message, a very important one.  The noise of the thing definitely makes our list of complaints.  On this first flight, we’ve been charged with evaluating every detail, including noise levels.  In our short mission, only 54.5 hrs. in space, we’ve checked everything: the flight-control systems, RCS maneuvering jets, our navigation platform, accessibility of displays and controls, camera operations, and on and on — right down to food preparation — and also evaluate how well our simulations match reality and the usefulness of checklists.

            And of course — public relations — TV broadcasts that make it seem we are breezing through orbit. Such was not the case yesterday, especially on three orbits — about five hours — in which Mission Control tore up the flight plan and made a new one on the run.  The results of those three orbits in on that teleprinter message.

            Alarmed by the 16 missing or partially missing tiles on the OMS pods, Mission Control was worried mightily about the state of the critical black tiles on Columbia‘s belly where we could not see.  They enlisted secret military “assets” to try to photograph the Shuttle in flight — camera telescopes in Hawaii and Florida.   And KH-11 spy satellites.   Hence, not a word over open air-to-ground communications. Except to make it sound normal:  A routine adjustment of three RCS (Reaction Control System, our smaller maneuvering jets) burns . . . and, oh, the addition of a fourth “test” burn.

            The changes were set to begin 24 hrs. into the flight, four hours after we woke up yesterday. The new plan came up in a long teleprinter message.  And 23 hrs. into flight, Capcom Joe Allen called in a nonchalant voice: “Curious to know if you’ve got message11 onboard.  It’s a pretty major change to the flight plan.” 

            Three RCS burns would adjust our position so the KH-11 could view our belly in sunlight.  The first encounter would occur on orbit 19, over the Atlantic, the second one orbit later (90 minutes) over the central U.S. The third, an orbit later over the U.S. was very marginal.  And amid all this, we have to appear on TV to take a call from Vice President George Bush.

            Everything was timed tight — and late changes were made adjusting parameters for the burns, the first of which came at 1 day 2 hrs. 42 min. into the flight over the Pacific to position for the first encounter.  We set up a gravity gradient attitude, nose towards the Earth, wings canted into the sun. We passed across the northern U.S. and out over the Atlantic.  The KH-11 on a steep orbit, 50 mi. higher than us, passed at a distance of 157 mi.  Two minute later, it gained its best angle to image us.

            We were already preparing for the next RCS burn that set up the second encounter.  On this orbit, we pass over the central U.S. — 67 mi. from the spy satellite.  But before this happens, the plan is modified, our attitude changed so that telescopic cameras at an Air Force station at Malibar, Florida, can try to photograph us.  Then we had quickly adjust position for the KH-11.  We make it (but alas, clouds obscure the ground cameras, and they gain no images).

            One orbit later, we did it all again for the KH-11’s last chance.  NASA did not receive the images until night, while we were sleeping.  Now the clatter of the teleprinter signals our reckoning.  And the word is . . .

            . . . The tiles are intact.  Everything looks clean.  We are go for a nominal return on orbit 36.  We test-fire all 44 RCS jets during orbit 33, close out the middeck.  And a crucial step, close the big clam-shell payload bay doors, comes on orbit 35.   They come together as smooth as silk.  We report, “Those doors are closed up and locked, just as they were supposed to.”

            We don our orange launch & entry suits, set our attitude, top towards earth, nose canted down, tail — and the two OMS engines, 6,000 lbs. thrust each — in the direction of travel.  

            Capcom Joe Allen calls, Columbia, your burn attitude looks good to us, and everything aboard looks good to us.  You are go for deorbit burn.”

            “OK, we understand — ready for deorbit burn.  Thank you now.  That’s the best news we’ve had in two-and-a-half days.”

            We’re 145 mi. above the South Indian Ocean.  . . . Fifteen seconds before the burn, we hit the EXEC button — telling the computer to execute the programmed burn.   The engines fire for 2 min. 37 sec., and we shed 200 mph — that’s enough to send us toward the atmosphere and a landing in an hour.

            We come into range of the tracking station at Yarragedee, Australia, and report, “Burn on time and nominal.”

            Capcom Joe Allen jokes, “We copy the shortest of all burn reports.”

            We now flip the vehicle around, nose first and pitched up 40 degrees so that those black belly tiles we now know are intact will take the brunt of the reentry heating, 2,700 degrees (F).  Over Guam, at an altitude of 85 mi. we start the three Auxiliary Power Units that drive our hydraulic systems, such as the elevons.  Start up is nominal. 

            We’re pass over Wake Island, 33 min. from landing.  

            At 400,000 ft. we touch the first traces of atmosphere, a point we call Entry Interface.  The force of our passing causes the atoms of the sparse upper atmosphere to shed electrons, become ionized — a plasma sheath that envelopes the Shuttle, and as in the days of John Glenn, cause a communications blackout.  Ours will last sixteen minutes.

            We are flying through the nightside of orbit over the Pacific.  Out of the corners of our eyes, we gain he first visible sign of the atmosphere entry — blips of the RCS jets reflects off the sparse atoms.  Then a pinkish glow builds along the sides of the nose.  It becomes almost as if flying through a neon tube.  We hit sunrise, which overwhelms the faint ionization glow.  We’re passing north of Hawaii, 15 min. from landing.

            Energy management, that’s the name of the game.  You have to balance speed vs. distance and altitude, bleeding off the speed (energy) to bring you at the landing point at a landing speed.  We manage the energy through a series of five S-curves, like a slalom skier.  We call them roll reversals.  The first three are controlled by the autopilot, the first beginning at 255,000 ft. with a starboard roll.

            And we’re startled to see our slip indicator peg at the max. reading of 2.5 degrees, meaning we’re sideslipping — canted off center, yawing to the side.  It’s alarming (and we have no way of knowing we’re actually yawed 4 degrees).  If it builds up, the wings will be torn off.  Jets fire and we oscillate three times before the computers bring the slip under control.

            We cannot take a breath, though.  Within seconds, the instruments show the big body flap below the Main Engines, which swivels to act as a hypersonic brake, which at this time should be deflected 7 degrees, is at 10 degrees . . . 12 degrees . . . 15 degrees . . . The max. allowable is 21 degrees . . . Now it’s at 16 degrees . . .

            And holds there, keeping us at the proper 40-degree angle of attack.  We continue riding the roll reversals, slowing down.  We’re a glider — and will have just one shot at landing at the 7-mi.-long lakebed runway at Edwards Air Force Base, California.

            We come into communications range and radio, “Hello, Houston, Columbia here.  We’re doing Mach 10.3 at 188 [thousand feet]. Our L over D [lift over drag] is nominal.

            Joe Allen say, “You’ve got perfect energy, perfect ground track.”  He keeps calling that everything is looking good. “Columbia, we show you cross the coast now.”

            We pass it at Big Sur at an altitude of 138,000 ft.  And exclaim, “What a way to come to California.”

            At slower speeds, where the autopilot may be less accurate, we want to take manual control, perform the final two roll reversals ourselves.  We take the stick and put the Shuttle through its paces, at 115,000 ft.  “Roll reversal complete,” we report, “Control looks good.  And perform the last one at 85,000 ft.  Columbia flies like a champ, responds fluidly — goes where you point it — bingo — and stays there until you move the stick again.  She’s a wonderful flying machine.

            We cross the coastal mountains . . . Bakersfield.  Joe Allen assures us, “Right on the money; right on the money.”

            Approaching Mach 1, about 5 min. to landing, we experience some buffeting, as could be a sign of a stall, but she smooths out at Mach 0.85.

            As planned, we actually pass over Edwards, loop to the runway, flying something we call the HAC — the Heading Alignment Circle, an imaginary cylinder of air with a 20,000-ft. diameter.  Joe Allen calls, “We see you coming right around the HAC — looking beautiful.”  

            We follow this circle for 225 degrees and then level off — the runway threshold 10 miles ahead.  On final approach.  Allen calls, “Your winds on the surface are calm.”    We descent at a steep 20-degree angle — five times as steep as a commercial jetliner — for Edwards 23, a clay-surfaced runway in the dry lakebed.

            Allen radios, “Right on the glide slope, approaching centerline.  Looking great.”

            We pull the nose up, hold her on a 1.5-degree glide.

            Just 250 ft. above the surface, we deploy the landing gear, which come down faster than we anticipate.   A chase plane at our side radios, “Gear down” and gives estimates of how far our wheels are above the surface:  Fifty feet . . . 40 . . . 20 . . .” and on down to the deck, calling out, “Touchdown.”  We ride on the main gear, the nose still in the air.  After 10 seconds, we gently lower the nose and the front gear touches down. And were rolling to wheels stop.

            Joe Allen calls, “Welcome home, Columbia.  Beautiful, beautiful.”

            We joke, “Do you want us to take it up to the hangar, Joe?”

            It takes about an hour before we can climb out of the ship, dance around the landing gear, marvel at our gem of the ocean of space.

            And only later, marvel at one more piece of luck.  No one knew of a gap in the tile filler around the starboard landing gear door. That small gap provided a path for a blowtorch of hot plasma to strike the underlying structure during the heat of reentry.  The aluminum skin of the door softened, buckled.

            Yet luckily it held.

            Add that to the list of near misses. 

            Never before — and never again — would the world see such a first flight.  Yes, it took a little luck.  And a mountain of skill.  

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s