“We see it, right seat. Looks fine. And configure Caution and Warning to ascent mode.”
In Endeavor’s tail section, the three auxiliary power units hummed and their small engines pumped warm hydraulic fluid through Endeavor’s veins. The wings and tall tail were now alive for flying like any airplane with elevons on the wings and the rudder fin on the tail. These control surfaces would fly the Return To Launch Site abort if necessary during the first four-and-a-half minutes of launch. Hydraulic fluid also surged at flight pressures within the three Space Shuttle Main Engines, SSME’s, to power the engines’ gimbal motors which will pivot the SSME nozzles to steer the rising ship.
As the countdown passed the five-minute mark, the automatic launch sequencer armed the ship’s explosive, self-destruction mechanism which would annihilate the solid boosters and would fatally rupture the external tank’s seams if the vessel flew off course.
“Range safety is hot, Endeavor. At four and a half, configure Main Propulsion Systems and ATVC.”
“Rogo, Flight. On your side, Jack, Panel Right-Two. Main engines: Helium isolation Loop A to GPC; helium Loop B to GPC; helium interconnect to GPC; liquid oxygen prevalves to lever-locked GPC; and, liquid hydrogen prevalves lever-locked GPC. Engine Interface Units: Main center, main left, and main right to on. Center engine, power source select to bus AC-1; left main engine, power source to AC-2; and, right main, power source to AC-3.”
“With you all the way, Skipper. She’s hot and ready to fly!” Enright’s hand swept the instrument panel at his right side.
“Okay, Jack. Your side: Helium crossover to GPC. On Panel Right-Four: Liquid oxygen feedline relief, lever-locked GPC; liquid hydrogen feedline relief, lever-locked GPC; liquid oxygen manifold pressure, lever-locked GPC; and, liquid hydrogen manifold pressure, lever-locked GPC.”
“She’s primed now, Skip!” Enright shouted into his glass faceplate. The hairs on the back of his neck tingled.
“And my side, Jack, Panel Center-Three: Main Propulsion System, limit shutdown to auto, and, vibration shutdown to auto… Okay, Flight: The Glass Lady is ready to roll.”
“Copy, AC. At T-4 minutes, your SSME helium purge is complete.”
“Mains purged, copy.”
“T-3 minutes and 45 seconds, Endeavor. We see your aero surfaces cycling.”
The elevons, combination elevator-ailerons at the back edges of Shuttle’s wings, flexed automatically in preparation for flight.
“And we see ASA cycling,” Enright confirmed as he scanned the rectangular indicator of control surface positions above the center, green television screen. The indicator’s pointers moved left and right as the elevons, vertical rudder, and the body flap beneath the three main engines moved briefly.
“This is the right seat. We have TVC hydraulics lever-locked neutral, systems One, Two, and Three, on Panel Right-Four. And on Panel Overhead-17, we have ATVC Channel Two. Solid booster separation, mode select is auto on Panel Center-Three. External tank separation lever-locked auto on Panel C-3. External tank umbilical doors, latch select lever-locked auto on Panel Right-Two.” “Copy, Jack. Ascent Thrust Vector Control is set. At T-three-and-a-half minutes, you are on internal power.”
Shuttle was now self-sufficient, cut off from ground electricity, and running on her own electrical fuel cells.
In her three fuel cells, liquid oxygen and liquid hydrogen join to form electricity, heat, and water beneath the floor of the closed payload bay. The fuel cells generate seven pounds of waste water each hour for the drinking water tanks and for the coolant systems.
The automatic launch sequencer swung the engine nozzles from side to side on the three, main engines to ready them to steer Endeavor by their shifting positions.
“At 3 minutes, Endeavor, SSME gimbal test complete.”
“We watched it, Flight.”
“Roger, AC. At 2 minutes and 55 seconds, ET LOX tank is sealed and coming up to flight pressure.”
In the massive external tank, glinting brown without paint to save weight in the sunshine, the liquid oxygen stopped venting vapors as the tank sealed for launch.
“Flight: We see the LOX vent arm leaving us.”
“Roger, AC, at 2 minutes 50 seconds.”
The launch tower’s hollow arm was attached to the nose of the external tank for replenishing the ET’s liquid oxygen as it boiled away. The fueling pipe pulled back from the ready starship.
High over Texas, a black laser gunship was streaking eastward as it rolled slowly in the airless, piercing sunshine. Following LACE, two Russians in their round Soyuz vessel soared over Nevada in pursuit 10 hours into their long day. The Soviet craft’s twin arrays of solar panels, like glass and silicon wings, sucked in the fierce daylight to generate electricity.
“At 2 minutes 45 seconds, Endeavor, your fuel cell ground supply is off.”
“Roger, Flight.”
Endeavor’s fuel cells now lapped at Shuttle’s own four tanks of liquid oxygen and four of liquid hydrogen beneath the floor of the payload bay with its blankets of silvered, plastic mylar.
“At two minutes and fifteen seconds, SSME gimbals are set.”
“We saw it, Flight.”
The shuttle’s three main engines swiveled into launch position to push Shuttle upward and slightly sideways at the instant of ignition. Like any winged airplane, the shuttle’s flight out of the atmosphere will generate lift from her massive wings. The direction of lift, perpendicular to Shuttle’s belly, would rip her backward away from the external tank if the main engines in Endeavor’s tail did not thrust forward in the direction of the external tank to counter the wings’ lifting forces.
“At one minute, fifty-seven seconds, the ET is flight-pressurized, Endeavor.”
“Thanks, Flight. Let’s light this candle!” Enright nearly shouted. He was ready and his temples pounded with the Go which surged breathlessly through his veins. Along the beach, faces were riveted on Endeavor and many lungs dared not breathe. Half a country away, a child-woman kissed a television screen, where her daddy lay on his back atop 4½ million pounds of iron and frothing explosives. Above the clear blue sky, LACE looked down upon Alabama.
“At one minute, sound suppression system is armed. Your OPS-1 looks clean.”
“Roger, Flight. Thank you.”
The launch tower was ready to deluge the base of Pad 39 with 300,000 gallons of water to carry away the teeth-rattling shock wave generated by the ignited solid boosters. The two SRB’s would light three seconds after Shuttle’s three main engines ignite.
“T-40 seconds.”
“Okay, Flight. We’re ready here. SRB flight recorders are on. Payload bay vents are open.”
“Copy, Jack. At minus 25 seconds, Shuttle GPC has the con. SRB hydraulics on-line and SRB gimbals activated.”
Endeavor’s own on-board computers, four primary and one in reserve, conducted the final seconds of the countdown. LACE watched as it crossed the gulf coast of Florida 130 nautical miles below. The Russians watched the red clay of Georgia. At the tail of each of the two solid boosters, the largest solid rocket motors ever built pivoted into launch position.
“T-18 seconds. SRB gimbals set.” The Spacecraft Communicator’s voice rose in pitch. A bird was ready to go.
“… T minus 16 seconds. Pyros armed!”
Explosive charges primed to cast off the spent solid boosters and the empty external tank were alive.
“… IMU internal at 12 seconds. God speed, old friends.”
Endeavor’s three inertial measurement units now steered the ship’s five internal computers. “Which way?” the computers demanded over miles of wire to warm black boxes. “Up,” the inertial sensors replied.