Authors: Douglas Savage
“About that, Jack. Why âMother?' I've been meanin' to ask you about that for about six months.”
“Easy: Calling it the General Purpose Computer is too damned cold and impersonal. The old GPC watches everything; it watches over us when we sleep, it tucks us in, it wakes us up, it monitors 3,000 parameters, it flushes the biffy; it does everything but wipe our noses . . . Only a Mother.” The small pilot in the right seat gently patted the glareshield atop the broad instrument panel. “Mother,” he smiled.
“ âMother' says entry interface in 30 seconds at Mach 24 point 6, Number One. Major Mode 304 is running.”
“I'm hangin' on, Skip. EI in 5, 4, 3, 2, and we've hit the wall!”
The cockpit shuddered as the uppermost wisps of the Earth's atmosphere 80 statute miles above the dark Pacific nipped at 100 tons of space glider. With all of her forward rocket thrusters shut down for re-entry, the shuttle is designed to come home from space without engines, hot and heavy, gliding in at 25 times the speed of sound.
A pink glow outside the large windows bathed the cockpit in cherry light as air friction seared the black belly of the shuttle. Outside, the re-entry heating is twice as hot as the melting temperature of the shuttle's aluminum skin. Only the ship's 35,000 heat-absorbing tiles of 99 percent pure glass fibers insulate it from incineration at Mach 25.
Mounting deceleration forces pushed the crew forward and their chest straps tightened as the Earth sucked fiercely at the glass-covered starship riding 40 degrees nose high across the nighttime Pacific Ocean.
Outside, air friction generated its glowing heat at the temperature where steel burns white. The cocoon of roaring fire in the sky enveloped the heavy vessel in a molten plasma sheath through which radio beams will not penetrate. The digital autopilot, DAP, flew the ship steadily eastward to her landing at Edwards Air Force Base, California.
“EI plus three. Elevons enable.” The airplane control surfaces on the broad wings were alive and flying along with shuttle's small jet thrusters in her tail section.
“I see it, Skip. We have aerosurface amplifiers on line. ASA is Go, Channel One.”
Far behind the flightdeck, the great aileron-elevator surfaces at the rearmost edges of the wings were guiding the plummeting starship in concert with the Reaction Control System jets in the tail.
“EI plus 4 and 40. At Mach 24, out of 280,000 feet.”
“Roger, Number One. Out of 280K. Roll jets inhibited aft. Dynamic pressure at ten.”
“I see it. Lift over drag is a tad high, Skip. Traj One is right down the slot.”
“Roger, Jack.”
The blazing daylight outside turned from pink to apple red as the autopilot steered through the fiery shock waves.
A siren wailed mournfully through each pilot's headphones.
“Master Alarm! Flight Control System! I got it, Jack.”
The commander pushed in the blinking Master Alarm light in front of his face to extinguish the alarm claxon.
“FCS Channel One to override . . . That's got her,” the long pilot sighed deeply.
“Five minutes into the blackout, Skip. FCS has the con at Mach 24. Stand by for roll reversal.”
The cockpit rolled slowly into a steep right turn laying the pilots on their sides.
“Out of 263K, Mach 22 point 3, 80 degrees of bank, Number One. Hang with it,” drawled the tall commander lazily.
“Auto looks good in roll rate at five degrees per second, Skipper.” The copilot scanned his winking green television screen as a tiny, bug-shaped shuttle chased a small, square box down the television screen's seven-inch-wide face. “Point 176 on G loading; drag at four; guidance internal. Range-to-go is 3,170 miles.”
“Mother is really flying hands-on today, Number One. Traj One looks super. Confirming aft pitch jets inhibited at 6½. How do the APU's look?”
“All three purrin' along. We're running main pump pressure low on Number Two. They're burning 1 percent propellant per minute. Temps and speeds all green.”
Outside, the brick-red glow ebbed to pink.
“Rog. At 12 minutes: Mach 21 out of 232,000. Standing by for equilibrium glide. Steady as she goes! Major Mode 305 is running.”
The Mission Commander counted off the minutes since entry interface when Shuttle began her plunge into the inferno over the Pacific at daybreak far below.
“Go at 15 since interface, Skipper. Mach 18 out of 220K. Range-to-go: 1,000 even.”
“Goin' to Trajectory Two on the left CRT. Auto roll reversal left. Velocity 18,450 feet per second . . . We're really hauling the mail, Number One.”
“SM alert, Skipper!”
“Systems management. You got it, Jack. Find the stinker.”
“Looks like the microwave landing system. Yeh, MLS. We popped breaker Main dc, Bus A on Number One receiver. I'm taggin' the breaker, Row E, panel Overhead Fourteen. Bringing MLS Number Two up on the line . . . That's got it. Lights out, Skip.”
“Out of 194K at Mach 16, Will. Constant Drag is initiated right down the slot. Profile at 33 feet per second. We're 715 miles from target, now out of 190,000 feet. Mach 15 at 17 minutes since entry.”
As the ship rolled on her side to dissipate the energy of flight en route to landing in California, the pink glow outside gave way to a morning sunrise 35 miles above the blue-green, north Pacific. The shuttle's nose slowly dropped from her nose-high entry attitude of 40 degrees toward a target attitude of 14 degrees nose-high a few minutes closer to home.
“Endeavor, Endeavor. We copy your S-band modulation, out of the blackout at interface plus 18 and a half minutes. You're Go out of 188,000 feet at Mach 13 point 8. Your range-to-go now 497 nautical miles. Confirm AOS Houston remote, via Buckhorn.”
“We have you, Flight. Real sweet ride inbound. We're right and tight here. Had a few alarms and FLT's, though. Showing Mach 10 point 5 out of 165K,” drawled the AC.
“Copy that, Endeavor. Understand a few Funny Little Things on the way home. Confirm your TACAN acquisition. And you're Go for speed brakes at Mach 10.”
“We have the TACAN beacon here, Flight. At Mach 9, we have auto roll reversal. Backin' her up with CSS.”
“Roger, Endeavor. Control Stick Steering. Your stick inputs look real crisp from down here.”
“Real tight, Flight.”
“We see it, Endeavor. You're on track out of 154,000, making Mach 9 point 8.”
“Copy, Flight. Trajectory Two is running. Out of 152,000 feet, Mach 8 point 8. Range-to-go-is 211.”
“Roger, Endeavor. Confirm body flap enabled.”
“This is the AC. Body flap is flappin'. Out of 151,000, at Mach 8 point 4.”
Beneath Shuttle's tail, the single thick body flap automatically flexed up and down under the three, lifeless shuttle main engines. The four primary flight computers cycled the body flap to ease the crushing burden of the descent upon the wings and to adjust the ship's center of gravity for precision steering homeward.
“Endeavor: You're still full of Go from down here. Anticipate the coastline at Mach 6 point 6 out of 138,000 feet.”
“And we have it! Big and beautiful, Flight. Amazing visual today!”
“Copy that, Shuttle. Standby to configure CSS.”
“Roger, Flight. We're 200 miles out, 130K up, and makin' Mach 6 point 4.”
“Copy, Endeavor. Telemetry modulation via Buckhorn is clean and clear. APU Number Two is still running hot and we're watching it. We see you 177 miles out, at Mach 6 even, descending through 124,000 feet.”
“Okay, buddy. We see Mach 5 point 5 out of 119,000 . . . Flash evaporators off and ammonia boilers on. Now Mach 5 point 3 out of 115,000. Range-to-go: 148. And we have the San Joaquin Valley at 12 o'clock low!”
Inside Shuttle's long body, two freon coolant loops are the ship's sweat glands, absorbing heat from crew, air supplies, and warm black boxes. During the fiery descent above feet into the sky, heat from the circulating freon coolant is dissipated overboard by the flash evaporators: complex pumps which turn heat into water steam for venting overboard. Below 120,000 feet, two ammonia boilers vaporize the freon circulation's heat.
“Roger, Endeavor. We show you 23 minutes since entry interface at Mach 5, out of 120,000 feet.”
“Endeavor copies,” the tall mission commander drawled. “I have manual roll reversal left. Your basic, standard rate turn at 3 degrees per second. Real crisp response from our glass lady this mornin'. We see Mach 4 point 5 out of 108,000. Range-to-go: 122 . . . Now 102,000 with 96 miles to go . . . Roll reversal damping out nicely out of 100,000 and Mach 3 point 6 . . . Rudder effective now at Mach 3 point 5. Very slight side slip here. No sweat.”
Like any airliner, the ship's tall tail now coordinated the fly-ing machine's turns left or right. Great jaws running the length of the tail's, 26-foot-long vertical rudder can open on each side of the tail fin. Opened, the rudder grabs the air stream to slow the vessel's forward speed. These are the speed brakes and they have the effect of the pilots hanging their feet out the door to drag in the dirt.
“Roger, Endeavor. Out of Mach 3 point 5, we see your Air Data Probes deployed. Digitals look good. At Mach 3, you're right down the slot coming through 90,000 feet.”
On each side of Shuttle's nose, the iron finger of an Air Data Probe braved the vicious slipstream. The computerized probes send airspeed, drag, and angle of attack information to the ship's computers.
“Thanks, California. At Mach 2 point 8 out of 89,000 feet, we're watchin' the final auto roll reversal right with 73 miles to home.”
“Copy, Endeavor,” the voice from Earth called.
“Out of 82,000 making Mach 2 point 5. Alpha 13 point 5 degrees up bubble on the nose. We have vertical situation displays running on the CRTs. Goin' back to Autoland now.”
The center Cathode Ray Tube, CRT, winked its green television graphics to the two airmen. With a tiny shuttle bug riding the vertical line of the television, the pilots marked their instrument approach at two and one half times the speed of sound to Edwards Air Force Base, California.
“Roger, right seat. You're Go from the ground.”
“And at 51 minutes since deorbit burn, we are in TAEM out of Mach 2 point 4.”
“Roger, AC. Terminal Area Energy Management. You're in the home stretch.”
“Roger. We have Mach 2 point 2 now. Payload bay vents open . . . Now Mach 1 point 8 out of 70,000. Range: 42 miles Now 68K high, Mach 1 point 5. Range: 39 . . . Now, Mach 1 point 3 out of 54,000.”
“You're right down the pike, Endeavor.”
“Thanks, Flight.”
“SM Alert, Flight !” Enright called from the right seat.
“We see it from here, right seat.”
“Okay. We've popped the breaker on radar altimeter Number One, Main Bus A, panel 0-14. I've tagged it, and radar altimeter Two is on line and flying.”
“Number One does it again for us, Flight,” the AC smiled.
“Endeavor, we have you out of 53,000 at Mach 1 point 2. You're 270 seconds to mains on the ground. Confirm state vector transfer.”
“Okay, Flight. We have state vectors loaded into the BFS,” the command pilot called with his right hand upon the Rotational Hand Controller between his knees.
“Copy, Endeavor. Backup Flight System and Computer Five loaded.”
“Endeavor is showing Mach One even, at 51,000 feet, 28 miles out.” The voice from the ground filled the pilot's headsets.
“Copy, Flight. We're feelin' a bit of transonic buffet in the cockpit. Go at Mach point 8, at 22 miles out. We have alpha angle eight degrees. Manual control now. Aft RCS jets off out of 45,000 feet.”
“Copy, Endeavor. You're 210 seconds from touchdown. We're seeing your speed brakes now. Expect HAC intercept at 320 knots passing 37,000.”
“Roger, Flight. We have Leuhman Ridge dead ahead. Turning left base, 33 degrees of bank here makin' 265 knots. Body flap is full manual and we're 16 degrees nose down. Pullin' 1.3G. Nose Wheel Steering to direct, panel Left-2.”
“Copy, Shuttle. Your EAS is a tad high at 290 knots. You're in the Heading Alignment Circle now.”
“We have it, Flight. Pulling 1.6G in the turn. Have Saddle-back Mountain ahead now.” The pilot in the right seat briefly squinted outside into the early-morning sun before turning his attention to the instrument panels at his face and Endeavor's touchdown only ninety seconds away.
“Okay, California. We have MLS out of 18,000 feet; TACAN inhibit. Fifteen miles out. Anti-Skid is on, panel Left-2.”
“Copy, Endeavor. We see you on Microwave Landing System. You're right down the slot for Runway 23. Wind is out of 240 at 05 knots, altimeter 29 point niner-five. We see you out of 15,000 feet and making 280 knots. Your attitude is nominal at minus 20 degrees. Now nine miles out at 13,000.”
“Gotcha, Flight. We're comin' around to final out of 12K, six and a half uprange. H-dot is 200 down.”
“Copy, Endeavor, descending at 200 feet per second. You're seventy-four seconds to wheels-on.”
“And, Endeavor, Chase Two is with you,” called a gleaming T-38 jet beside Shuttle's left wingtip. “We're at your nine o'clock and see your vent doors open in payload bay.”
“Thanks, Chase,” Colonel Parker acknowledged. “Out of 3,500, making 285 knots over the fenceâa tad hot. Speed brakes deployed 80 percent.”
Completing his turn to final approach and aligning his 100-ton glider with the runway centerline, the command pilot squinted through a six-inch square frame set into the forward windshield. Inside the black frame of his Kaiser Electronics Heads-Up Display, Will Parker could see the runway coming up quickly. The see-through HUD is clear glass like the windshield all around it. But on its glass face were numbers and symbols. Shuttle electronics and her humming black boxes projected critical flight information onto the small clear screen.
Along the left side of the HUD video image, a vertical column of numbers told the pilot his air speed. Another column of numbers on the right edge of the HUD face showed distance to the ground. And in the center of the glass screen, a white video “X” moved left or right of the centerline of the real runway below and half a minute away. By looking outside through the HUD frame on their windshields, both airmen could see exactly how their approach numbers looked without dropping their weary eyes inside the cockpit to the instruments above their knees. HUD keeps a pilot's eyeballs where they belong. The device first flew in space on Shuttle Six in April 1983. Will Parker flew it now.