Authors: Douglas Savage
“Go at 1 minute fifty-three seconds, Endeavor.”
“Thanks, Flight. We're right and tight in the sky!” the firm voice drawled confidently as Endeavor's nose dropped to 39 degrees below vertical 120,000 feet high at three times the speed of sound.
“Go at 2 minutes, Will. Mach 4 out of 136,000 feet. Go for SRB separation.”
“Rogo, Flight. Flash evaporators on. And we see PC less than 50 at 2 plus 06.”
Inside Shuttle's fuming tail, the heat dissipating flash evaporators began sweating out the heat from Endeavor's systems. The green television screens on the flightdeck told the two airmen that the thrust level in each solid booster was trailing off to lessen the shock of an abrupt burn-out when their fuel was exhausted. Sensors felt each booster's engine pressure drop to 50 pounds per square inch.
“BECO! And booster away.”
“Roger, Will. Booster engine cut-off. Looks good.”
“And it's much smoother now, Flight, at 2 plus 15.”
“Copy, that, Jack.”
Spent and dry, the two dead solid boosters shut down simultaneously. Four small rockets in the nose of each SRB and four rockets in the tail of each, burst with 22,500 pounds of thrust each for seven-tenths of a second to shove the lifeless boosters clear of Endeavor and the external tank at four and one-half times the speed of sound, 30 nautical miles high. At 2,891 knots true airspeed, the ship climbed past the separated SRB's.
The two discarded solid boosters will continue to coast upward by their own momentum until they reach 200,000 feet high. From there, they will arc down toward the ocean. Riding parachutes manufactured in Manchester, Connecticut, by Pioneer Parachute Company, the SRB's will glide into the warm sea 140 miles east of the Cape. Landing and floating only one mile apart, the empty silos will be plucked from the sea, refitted, recharged, and reused.
“Real smooth ride at 2 plus 26. Guidance is now closed loop, Flight. Center television showing second-stage trajectory.”
“Copy, Jack. You're right down the slot at two and one-half minutes out. We see Major Mode 103 now running in the GPC. Your flash evaporator is Go.”
Against the purple sky, the faint blue flames of the three main engines could no longer be seen from the ground. Only a grotesquely contorted contrail from the spent SRB's marred the sky where high altitude winds tied the SRB exhaust plumes into a knot.
Between the third and fourth minutes of powered flight, Endeavor, riding heads down beneath her half-dry external tank, accelerated from 4.6 to 6.3 times the speed of sound as she climbed from 43 to 63 nautical miles high. Her nose slowly dropped toward the sea, a clearly curved blue line when viewed upside down by the two fliers behind their six windows.
“Endeavor is press to MECO at four minutes.”
“Thanks, Flight. Go in the sky.”
The ship now carried sufficient energy to reach her main engine cut-off goal should one main engine fail early. Endeavor screamed past 65 nautical miles in altitude, where her gray carbon-carbon composite nose cap glowed a dull red from the intense heat of high speed air friction.
“Press to ATO at 4 plus 20.”
“Copy that, Flight. Pulling three G's and we're real tight up here.”
“And from the ground too, Will.”
Should Shuttle lose an engine now, she could still struggle upward to execute an Abort to Orbit, or ATO.
“Negative return at 04 plus 26.”
“Roger, Flight. Then we'll
go forward!”
“Do that, Jack.”
Endeavor was now too high and too far out to sea to turn around to shoot an emergency landing on Cape Canaveral's runway.
For the next several seconds, the crew rode the most dangerous part of their ascent in terms of abort options. An engine failure during this brief period leaves them too far out over the Atlantic to return to the Cape and too slow to coast to an emergency landing in Europe. Main engine failure now would reduce the 1.2 billion-dollar ship to only a banner headline in the morning newspaper.
“And you're press to Rota, Endeavor.”
Leaving behind them the momentary No Man's Land of their abort options, Shuttle can now make an emergency landing if she blows only one main engine. She could use two surviving engines to reach the U.S. Navy air station at Rota, Spain, on the far side of the Atlantic.
Endeavor rode her blue flames into the black, airless sky. Only blue ocean, upside down, can be seen outside the flightdeck windows. The pilots are pressed into their seats by forces which triple their body weight.
“At 06 plus 05, Endeavor is single-engine Rota.”
“Copy, Flight. We're Go at six minutes five seconds.”
Even with a failure in two of her three main engines, Shuttle now carried enough speed to reach an emergency landing in Rota, Spain, without getting her feet wet.
In the cockpit of white lights and three green television screens on the forward instrument panel, there is absolutely no noise, no vibration, and no feeling of movement. Only the acceleration load of 3 G's tells the inverted crew that they are in motion hanging by their lap belts.
“Single engine press to MECO at 06 plus 50, Endeavor.”
“Roger, Flight. Good news!”
Shuttle could now make a fragile orbit even if she should lose two of her three main engines. Endeavor pressed onward, upside down, 68 nautical miles above the mid-Atlantic.
Far below and behind, 7 minutes and 13 seconds into the flight, the two SRB's splashed into the chill sea close to the booster recovery ship USS
Mercury
.
“Throttles down!” the Aircraft Commander called.
“Copy, AC. You're Go from here.”
The flight computers automatically reduced the power on each main engine from 104 percent to 68 percent for the final sprint into space. This would reduce the structural strain of an abrupt burn-out when the SSME's completed their eight and one-half minutes of furious work.
The inertial measurement units sought out their keyhole in the velvet black sky. The primary, on-board computers found their invisible target.
“MECO at 08 plus 33!”
“We see it, Endeavor. Main engine cut-off. Energy state looks right on, Endeavor.”
Instantly, the engines stopped and the fliers floated weightlessly against their seat belts. Jacob Enright immediately grabbed the glareshield on the dashboard before his face. He was seized by the pilots' somatogravic illusion of pitching forward, head-over-heels, when the forward acceleration suddenly stopped with main engine burn-out.
Riding straight and level upside down, 900 statute miles east of Pad 39-A, 70 nautical miles into the black sky, Endeavor's engines are quiet. Eight and one-half minutes aloft, the 100-ton bird with the nearly empty external tank attached to her belly coasts bottoms-up at the velocity of five miles per second. Even with her engines stilled, Endeavor still climbed upward at a rate of 220 feet per second. The two pilots were weightless in Zero-G and they could feel their faces become puffy and swollen as blood begins to pool in their cheeks. Their earth-borne circulatory systems did not know what to do with their blood when heart and veins do not have to work against gravity's pull. Tiny pools of blood collected within the hair-fine capillaries of the crew's faces. Weightlessness also increased the fluid pressure inside their eyeballs by 25 percent: an unsolved problem which could mean blindness on long flights to the planets.
In the excruciating sunlight of the black sky, where no stars shine in daytime, Endeavor glided silently, nose forward, wings level and belly up. The brown external tank was still bolted to Shuttle's underside.
“Major Mode 104 now running. Mother likes it. We're looking at digitals of 80 by 13.”
“Copy, Jack. We see 104 in the computers and we concur with an orbit of 80 by 13 nautical miles. LOS momentarily at Bermuda. AOS Madrid in ten minutes. You are Go for OMS-1 burn at 10 plus 34. First sunset at 32 minutes out . . . Configure LOS Bermuda . . .”
Nine minutes from the still hot and steaming Pad 39, almost 1,000 miles behind them, Endeavor coasted out of radio range with the Bermuda Island tracking station.
Endeavor's preliminary orbit with a high point of 80 nautical miles and a low point of 13 miles was an illusion of orbital physics. Shuttle carried sufficient energy to whirl around the blue planet in this lopsided orbit for years before gravity's immutable tug cracks the delicate balance between the ship's velocity and her 100-ton mass. But in reality, the planet's gossamer envelope of air would wrench Endeavor from an orbit so low within an hour. More kinetic energy must be added to Endeavor to hoist her higher if she is to keep her aluminum toes from tripping over the atmosphere's fiery fingers. With the external tank nearly dry and the three main engines quiet and cooling, Endeavor must ignite her two powerful OMS engines tucked in her tail to raise the orbit to a survivable energy state. The OMS-1 rocket maneuver would loft Shuttle into a slightly safer, higher orbit 10½ minutes into the flight, in mid-Atlantic out of earshot of any tracking station. Another OMS firing, OMS-2, in half an hour would finish the job of inserting Endeavor into a safe orbit. But first, Shuttle must cast off the external tank which glistens with frost in the burning daylight under the ship's inverted belly. The flight computers are programmed to disconnect the ET.
“Attitude hold, Skipper,” Enright called 8 minutes 50 seconds into his first ride into space.
“Mother has it, Number One,” the command pilot replied. “Auto sep . . . ET away!”
Automatically, explosive charges detonated without sound in the airless blackness. The three support brackets holding the ET to Shuttle ruptured. As the brown tank drifted upward into the sky away from the belly-up Shuttle, Endeavor's reaction control system's small jets fired automatically for five seconds. The little jets pushed Endeavor downward and away from the freed external tank.
“ET free. Evasive maneuver complete. Delta-V at 4 feet per second, Jack.”
The upside-down pilots could not see the ET rise away from Endeavor as Shuttle slipped downward at a rate of four feet per second. The green television screen read out confirmation of ET separation.
“Goin' to normal on the Caution and Warning, Jack.”
As the ET drifted away, a valve in its frosted nose popped open automatically. Unburned fuel vapors shot from the open valve like a small rocket engine. The programmed release of gas will cause the tank to tumble end over end to assure that it will incinerate when it plows into the atmosphere over the Indian Ocean. Since Shuttle had yet to perform the OMS-1 rocket burn, the jettisoned tank's lonesome orbit is fatally low.
“Mother has our OMS-1 targets, Jack. Inertial attitude, deadbands are 3.5 degrees attitude, 0.3 degrees per second in rate, and 0.2 degrees per second in discrete rate.” The command pilot scanned the left of three television screens at the center of the forward instrument panel. “TIG at 10 plus 32; BT 01 plus 27; Delta-V 165; Alpha plus 05 degrees by DAP in Vernier mode.”
“Watching, Skipper.”
Mother's green face told her pilots that the first burn of the orbital maneuvering system's two rockets would occur automatically if given the go-ahead at 10 minutes 32 seconds into the flight and would ignite for 1½ minutes until Endeavor had picked up another 165 feet per second forward velocity to add to her speed over the sea of 25,668 feet per second. The digital autopilot, the DAP, and Mother set Endeavor's upside-down nose five degrees above the sea's blue horizon. Shuttle coasted toward Spain with the ship flying belly-up, wings level, nose pointed toward Europe.
The Colonel pressed his PROCEED computer key on the small keyboard by his gloved right hand.
“TIG minus 5, 4, 3, 2, 1. Ignition!” the AC called out.
Eighty-five feet behind the pilots, each OMS rocket in Endeavor's tail thundered to life with each engine pounding away with three tons of thrust. As the two engines fired, the flight computers automatically began to dump overboard the unburned propellants trapped in Shuttle's internal fuel lines from the quiet main engines. First, 3,700 pounds of liquid oxygen spewed out through the cooling center main engine. When this was completed, 1,700 pounds of unused liquid hydrogen would be dumped into space through the umbilical vent on the starboard side of Endeavor's tail. Helium gas would then flood the frigid fuel lines to drive out any traces of unburned propellants to avert an explosion in Shuttle's bowels.
“Shutdown!” the AC called as Mother pulled the plug on the two OMS rockets after 87 seconds. “Looks good, Jack. Delta-V right on at 165 for an orbit of 132 by 57 nautical miles. On our way now, Buddy!”
Endeavor, well clear of the tumbling external tank, climbed toward her higher, safer orbit in pursuit of LACE. Their new orbit's low point of 57 nautical miles was still fatally low. But the OMS-2 burn in 28 minutes would fix that.
“MPS inerting routine is continuing, Skipper. Major Mode 105 now running.”
“Roger, Number One. Douche 'er out, Jack.”
The cleansing of the Main Propulsion System would continue for another ten minutes.
“Close your doors, Jack.”
The copilot anxiously watched five lights on the cluttered instrument panels at his right side.
“ET umbilical doors closed and latched, Skipper.”
Enright pushed five lighted pushbuttons which confirmed that two large doors had closed and sealed on the underside of the rear of Endeavor's black wings. Through these two doors in the ship's belly, the ET's 17-inch-wide pipes had passed into Shuttle's insides to feed propellants from the ET into Shuttle's three main engines, which remain permanently attached to the ship's square tail section. Failure to seal the doors, each four feet square, would spell doom during re-entry's searing heat.
“OPS-2, Major Mode 205, running in the GPC.”
“ 'Kay, Skipper.”
“And at 15 minutes out, let's secure the APU's, Jack.”