“Copy, Jack. Before you go over the edge, give us a hack on RMS power-up. And we want you to begin cabin-depress routine when able.”
“Just gettin’ to the RMS qualification runs, Colorado. Should be well into the manipulator test by Australia. And we copy on the delta-P.”
The earphones crackled high above sleeping Madagascar two and one-fourth hours into the mission.
“Colorado?” the AC called into the darkness.
“Guess they’re out chasin’ mountain women, Skipper.”
“Can’t blame ’em.”
“I’m about ready for RMS power-up, Skip.”
“ ’Kay. Let me cruise up front to pop the cabin vents while you’re breakin’ out the RMS checklist. Holler if you have any ear trouble when I bleed the pressure.”
“ ’Kay… And no handstands,” Enright called over his left shoulder as the AC disconnected his hoses and cables.
Free of the beta cloth-covered air hoses, the AC shoved off from the aft station. He floated with his arms and legs parallel to the floor. He swam to his left seat forward.
“ ‘It’s a bird, it’s a plane…’ ” the horizontal floating pilot called through his open faceplate. Enright could not hear his captain’s pleasure.
The AC floated sideways into his seat. He did not connect his lap belt but held his position with his right hand upon the glareshield overhanging the forward instrument panel.
“Got me, Jack?” the AC called after plugging in his communication cable.
“Five by, Skip.”
Parker’s body did not touch his seat as his left hand rested upon a triangular instrument array beneath his left forearm.
“Okay, Jack… Cabin relief enable… Now!” As the AC flipped and held down two spring-loaded toggle switches, air hissed out of the flightdeck. The AC felt his ears pop and he swallowed to equalize the pressure inside his head. As he depressed the two switches, the Colonel watched the fourth from the left of eleven vertical meters set into the ceiling just above the center windows. The meter’s vertical tape slowly moved beside its fixed pointer. As he read the cabin pressure gauge, air pressure in the flightdeck dropped from its normal 15 pounds down to 10.2 pounds per square inch.
At both ends of the flightdeck, the two crewmen cleared their ears by yawning and by swallowing as the cabin pressure bled down.
The cabin relief maneuver was essential to Enright’s planned walk in space to attach the grapple fixture to LACE. The object of lowering cabin pressure by one-third was to protect Enright from the “bends” during his extravehicular activity, EVA, outside. Since the EVA suit would be pressurized with pure oxygen at only 4.3 pounds per square inch, nitrogen gas from the cabin air mixture would bubble out into Enright’s blood if he went from sea level pressure into the low pressure of the EVA space suit which was stowed in the mid-deck airlock. Such a bloodstream bubble in Enright’s brain or lungs would mean an agonizing and convulsing death in space. To avoid the normal Shuttle EVA preparation of pre-breathing pure oxygen for three hours before going outside, the lowering of the pressure in the cabin’s oxygen-nitrogen mixture for several hours would remove most of the nitrogen from Enright’s blood. Such was hoped. The Shuttle program had abandoned the cabin-pressure-reduction routine in 1982 as only marginally reliable. The program adopted the more reliable three hours of oxygen prebreathing before the EVA scheduled for Shuttle Five in November 1982. A whole day at the lower pressure was called for by the manual. That much time is required to wash most of the dissolved nitrogen from astronauts’ blood. Now, Parker and Enright did not have time to wait and to do things by the numbers.
“Ten point two and holding,” the AC called as he tightly held his nose while blowing hard through sealed nostrils to clear his ears. He ordered Mother to hold that level of cabin pressure.
“Okay back here, Will. Ready for RMS routine.”
“Comin’ back, Jack.”
Parker swam back to Enright’s side where he plugged into his hoses and cables.
Two hours and twenty minutes out, Endeavor flew over the black sea toward Australia now six minutes and 2,000 miles away.
Jacob Enright at the port side of the rear flightdeck had the inch-thick checklists for the RMS arm lashed to the aft instrument consoles. The pilots prepared to bring the remote manipulator system to life in preparation for capturing LACE with the wire snare at the arm’s far end.
Standing shoulder-to-shoulder and facing rearward, the fliers raced the clock to begin the manipulator tests before interruption by Mission Control in Colorado.
The RMS built by Spar Aerospace in Toronto is a 100-million-dollar gift to the American space program from Canada. The exquisitely complex manipulator arm is the single piece of equipment in the billion-dollar starship which cost the American taxpayers nothing.
Enright flexed his knees to reach Panel Aft-14 below his waist. He crouched to read the controls for an emergency jettison of the whole 50-foot-long arm into space.
“RMS jettison pyros, lever-locked safe; jettison command lever-locked safe; retention latches jettison forward, lever-locked safe; midships latch, lever-locked safe; and, aft latch jettison, lever-locked safe… She’s not goin’ anyplace, Skipper.”
“Let’s do it then, Jack.”
“Roger,” Enright said over the voice-activated intercom behind his closed, laser-reflecting faceplate. The copilot worked the chest-high control panels: “At Panel-A8A2: Primary power on; command switch to deploy; RMS latches from latch to off to set release.”
Two black-and-white television screens beside Enright’s right shoulder blinked “RMS released.” The 905-pound arm was free and resting upon its open triple-latch rests on the portside sill of the payload bay. “And heater switch to auto.”
Inside the 15-inch-thick arm, 26 automatic heaters and thermostats came to life to keep the motors in the arm’s shoulder, elbow, and wrist joints no colder than 14 degrees Fahrenheit when Endeavor sped through nighttime’s cold of 250 degrees Fahrenheit below zero.
Enright laid his ungloved left hand upon Panel A8A1 at chest level. On the console’s lower left corner, a small, red and white maple-leaf Canadian flag flew 130 nautical miles over the southernmost reaches of the Indian Ocean.
“Safing to auto,” Enright called as he went down his thick checklist. “Brakes lever-locked off. Shoulder brace, lever-locked release.” The launch phase, support strut secured to the arm’s shoulder joint detached from the RMS arm outside Enright’s rear window. “End effector switch to auto; end effector barber-poled derigidize, open, and capture snare extend.”
Fifty feet away from the arm’s shoulder joint, the arm’s end effector is its electronic fingers, a tubular complex with three wire snares which close around the arm’s target when a trigger is squeezed on the arm’s pistol-grip rotational hand controller beside Enright’s right hand. With the end effector unit’s wire snare, the RMS can grab and deploy from the payload bay a 65,000-pound package. The same snare can retrieve from space and stow in the bay a 32,000-pound object.
“Parameter select to POSITION.”
Enright turned a round knob on the Canadian instrument console. He stopped the six-position knob at its POSITION mark. Above the knob, three glass windows with digital numbers blinked to life.
With the setting knob, the pilot of the RMS selects the information to be displayed in the three two-inch-long windows. The display shows one of three dimensions on each dial face. The meters can display the end effector’s position in an X-Y-Z coordinate axis, or its attitude in degrees of pitch, roll, and yaw. Or, the knob can direct the three windows to display the angle of bend in the arm’s shoulder, elbow, and wrist joints, or the speed of the end effector through space, or the rate of angular change of the moving joints, or the meters can be commanded to show three sets of arm temperatures.