“And to you, Australia. But it’s afternoon up here,” the AC drawled, pressing his mike button on his chest. “How’s our downlink?”
“Real crisp, Endeavor. With you four minutes this pass. The CCTV from the wrist looks super from here. Continue with the RMS tests. We’d like you to run the arm to the end of its reach envelope aft in direct-drive, please. When you reach singularity, bring it back to keel Number Two in manual-backup. You’ll be on your own by then for going on to PDP deployment.”
“Gotcha, Flight,” Enright called, pressing his mike button. “Goin’ to direct-drive now.”
The arm’s fourth manual mode of operation is one of two fully manual systems. In direct-drive, the arm is flown one joint at a time by the joint-selector knob and the command toggle switch. But unlike the three modes already tested, the direct-drive system has no computer assistance from Mother. It is strictly an eyeball operation with the pilots’ aids limited to the aft and overhead windows and the arm’s own television cameras. The steering commands bypass Mother and run by hard wire from the instrument panel to each joint motor. The only usable electronic aids to the crew are the three position meters in front of Enright which were set to show the end effector’s position in inches from the zero datum point.
“Runnin’ in direct, Flight,” Enright called as he switched first to SHOULDER-YAW.
Enright steered the upper arm which slowly moved from its shoulder joint affixed to Shuttle in the direction of the far diagonal end of the cargo bay on the starboard side. Parker at Enright’s left watched the drooping wrist move outside his aft window.
“Two feet per second, Flight.”
“We see it, Jack. Super view down here of the thermal blankets from the wrist camera.”
“EEU at X0 equals 941 inches,” Enright radioed as the parameter dial confirmed that the end effector was at the center point of the bay’s length.
Switching to ELBOW, Enright flicked the toggle switch which commanded the forearm of the RMS to reach toward the bay’s far end. As Endeavor sped over eastern Australia in pre-dawn darkness, the 278-inch-long forearm slowly maneuvered toward the aft bay area outside Parker’s window.
When a tail thruster automatically thumped once to hold Shuttle’s attitude, the arm oscillated very slightly. The joint motors in their safing mode momentarily locked the arm in place until the vibration through the arm stopped.
With the upper arm and forearm nearly horizontal, Enright switched to WRIST-PITCH and the toggle switch sent the EEU reaching for the bay’s far corner.
A yellow SINGULARITY caution light flashed on the control panel. The arm could reach no further.
“Okay, Flight,” Enright radioed. “We’re at reach envelope. The EEU is stopped at X0 equals plus 1,159 inches, Y0 at plus 82 point 5, and Z0 is at plus 444 inches. Good clearance around the OSS pallet back there.”
“We see it, Jack. We’re looking via the wrist camera right into the eye of the aft bulkhead TV camera. Get on to approaching the PDP package. Forget about keel Two. We’re only with you another minute.”
“Rog. Goin’ to manual backup.”
The fifth and final RMS steering mode is the totally manual, eyeballs-only mechanism. The arm is flown by an entirely separate hard wire system isolated from all other arm circuits. There is no computer help, not even from the digital position meters. It is a pilot’s job.
“Backup engaged,” Enright advised as he used his left hand to control the joint-selector knob and the command toggle switch. Although the other semi-manual modes all use the same joint-selector knob and command toggle switch, manual backup operation has its own of both, totally separate from any other RMS circuitry. The isolated controls are at the lower left corner of the chest-high Canadian console.
Steering the arm one joint at a time, Enright guided it toward the payload package in the rear third of the bay. He steered the arm toward the Office of Space Science (OSS) pallet bolted to the bay’s floor as Parker spotted for him out his starboard window. “Up… Up… Easy, Jack… Wrist left… Elbow down… Easy.” As the command pilot called out the steering commands, Enright’s busy hands complied. His eyes darted from window to television to window.
“You’re about over the edge, guys, at 02 plus 37. Next contact in 18 minutes via Hawaii. Sunrise in 10. Good…”
“Copy, Australia” the taller airman drawled. “Peace and quiet at last, Number One,” he sighed into the voice-activated intercom.
“With you on that one, Skipper. Goin’ to manual-augmented… Let Mother help.”
“Okay, Jack.”
Endeavor, Soyuz ever silent, and LACE rolling peacefully in the glare of the lights from Soyuz, all crossed the Australian eastern coastline at Brisbane for the dark South Pacific. “Looky there, Skip,” Enright called with excitement as he pointed out his window toward Endeavor’s tail. “Think I saw the glow. Let’s kill the bay floods, just for a second.”
“Think so? Okay, Jack.”
Enright’s left hand threw the six switches which extinguished the bay’s floodlights. The payload bay went black, the perfect moist blackness of the nighttime South Pacific. The RMS arm was parked a foot above the OSS pallet.
“Gawd,” Parker breathed. “Good eye, Jack. Incredible.”
The fliers were transfixed at their aft windows.
Outside, Endeavor’s tail and the bulbous protrusions of the OMS pods glowed orange. A fluorescent orange glow, like a neon sign flashing “eat” bathed Shuttle’s back end. The strange glow was first reported by Shuttle Three in April 1982. On Shuttle’s body, high altitude atoms of oxygen struck the ship in the nearly perfect vacuum of near-Earth space. At Shuttle’s velocity of 17,500 miles per hour, the occasional stray atoms of oxygen 130 nautical miles aloft hit the vehicle so hard that their energy caused the ionic orange glow visible only in darkness. The tail shimmered in the eerie and ghostly glow. A crusty old sailor before the mast would have called it St. Elmo’s Fire.
“Amazing, Number One. But let’s hit the floods and get the PDP out. Wanna see what LACE is sweating out.”
Enright nodded and revived the bay’s arc lights one at a time. The arm still hung motionless where it had been parked.
As Endeavor sped over the dark South Pacific toward the New Hebrides Islands 1,200 miles and four flying minutes away, Colonel Parker floated at Enright’s left side. The AC’s left boot was anchored to a foot restraint on the flightdeck floor. His right foot was cocked behind his left ankle. With his weightless legs flexed at the knees, Parker had assumed the resting position of horses. Without thought, Parker stroked his painful and throbbing right leg. The knee pain radiated upward into his thigh across his groin and into his right hip. His sigh of anguish rode sufficient breath to trigger his voice-activated microphone at his lips.
“You okay, Will?” Enright queried with both of his hands full of RMS controls.
“Huh?… Right and tight, Number One… While you fly the arm to the plasma package, I’m goin’ to visit the biffy.”
“Don’t fall in, Will. It’s a long way down!.. And don’t flush until the train leaves the station.” Enright grinned behind his closed visor toward the tall pilot’s back. The AC had already pulled his plugs and floated toward the forward cockpit.
Drifting slowly, the command pilot floated horizontally toward the six dark front windows of the cockpit. With a push from his hand upon the back of his empty front seat, Parker did a half somersault and sank headfirst down the hatchway in the floor behind his left seat.
The weightless airman entered the dark mid-deck. He did a momentary handstand before twisting rightside up with a gentle kick on the ceiling by the square hole through which he had just floated headfirst.