Stephen Coonts - Combat

“Shit,” Diane whispered when spotting the vehicle upside down and jammed against the rear of the bay. Actually, most everything else that she could see through the narrow opening appeared out of place or missing.

Before she could attempt an Extravehicular Activity to check the damage done to the AMV and the other equipment in the payload bay, Diane had to start the hourlong 100 percent pure-oxygen prebreathing.

After a brief check that the integral oxygen tank for prebreathing was not operational, Diane grabbed the emergency portable oxygen unit off a built-in inner wall to her left. She actually needed the portable unit even if she wasn’t planning an EVA because the oxygen level inside the airlock was falling below the safety level.

She placed the clear plastic mask over her nose and mouth and turned a red knob on the pint-size canister connected to the mask through a thin plastic tube. Letting the canister float overhead, Diane stripped naked. Next she opened a compartment containing most of the “underwear” garments she would have to put on prior to donning the actual EMU — the space suit designed to provided pressure, thermal and micrometeoroid protection, communications, and full environmental control support for one astronaut. The EMU’s thick skin consisted of a number of layers, starting with an inner layer of urethane-coated nylon, followed by a restraining layer of Dacron, a thermal layer of neoprene-coated nylon, five layers of aluminized Mylar laminated with Dacron scrim, and an outermost layer made of Goretex, Kevlar, and Nomex for micrometeoroid protection.

Diane put on the Urine Collection Device — a pouch capable of holding one quart of liquid, derived from a device used by people with malfunctioning kidneys. She followed that with the Liquid Cooling and Ventilation Garment (LCVG) which, similar to long underwear, consisted of a one-piece front-zippered suit made of a stretch-nylon fabric but laced with over three hundred feet of plastic tubing, through which chilled water would flow to control her body temperature.

The undergarments out of the way, and while still breathing directly from the oxygen canister, Diane connected the LCVG’s electrical harness to the upper torso section of the multilayered EMU she retrieved from another airlock compartment. She removed the EVA checklist attached to the upper torso’s left sleeve and, having done her share of space walks, she gave it a quick scan before flinging it aside.

She attached the electrical harness to the EMU. Because the orbiter’s communications system was dead, the electrical harness — designed to provide her with a biomedical and communications link to Mission Control — would not work until she reached the space station.

Next, she grabbed the connecting waist ring of the lower torso section — or suit pants — of the EMU, and, while floating in the middle of the airlock, she guided both legs into it. The lower torso came with boots, and joints in the hip, knee, and ankle to give the astronaut maximum mobility. Briefly removing the oxygen mask while extending both arms straight up, Diane “dived” into the upper torso section floating overhead, reattached the oxygen mask, and connected the tubing from the EMU to the Liquid Cooling and Ventilation Garment before joining and securing the upper and lower torso sections with the waist-entry closures of the connecting rings.

She checked her watch. According to NASA regulations, she had another forty minutes of prebreathing before she could go outside, but because the crippled orbiter could not provide her suit with cooling water, oxygen, and electrical power during the long prebreathing period to conserve the oxygen and battery power inside the EMU’s backpack for actual EVA time, Diane decided to risk a prebreathing shortcut to maximize the eight hours’ worth of oxygen of the Primary Life Support System (PLSS) backpack unit. Besides, her emergency oxygen canister would be exhausted in another five minutes and the air quality inside the airlock was already below the safe level.

Diane backed herself against one of two PLSS units and secured it in place. She made the appropriate connections for feedwater and oxygen, and secured the display and control module on the front, which showed alpha and numeric readouts of oxygen level, fuel, and power remaining in the PLSS.

She grabbed one of the helmets, a clear polycarbonate pressure bubble with a neck connecting ring, and rubbed an antifog compound on the inside of the helmet. Next she placed a communications cap on her head and connected it to the EMU electrical harness. Grabbing a pair of gloves and putting them on, she fastened the ends to the locking rings at the end of each EMU sleeve.

Taking a final breath of 100 percent oxygen from the portable unit, Diane removed the clear mask and let it float over head. Next, she lowered the helmet and locked it in place. Powering up the PLSS, she breathed again while pressurizing the suit to 16.7 PSI at 100 percent oxygen, two PSI above the airlock pressure, to create a pressure differential. Diane’s body responded with a slight discomfort in her ears and sinus cavities. She tried to compensate by yawning and swallowing, but the pressure in her ears remained. Pressing her nose against a small sponge mounted to her right, inside the helmet ring, Diane blew with her mouth closed, forcing air inside her ear cavities and equalizing the pressure.

Her eyes on the display module attached to her chest, she turned off the PLSS and waited one minute to check for suit leaks. The pressure dropped to 16.6 PSI, well within the maximum allowable rate of leakage of the shuttle EMU of 0.2 PSI per minute.

Satisfied, she dropped the pressure to 14.7 PSI and waited ten more minutes while slowly starting the airlock pressure bleed-down. The moment the pressure outside equaled the pressure inside the airlock, Diane checked the chest-mounted timer.

Forty-five minutes of prebreathing. It’ll have to do.

She took two additional minutes to bring the EMU pressure down gradually to six PSI instead of the recommended four PSI for maximum EMU flexibility without excessive muscle fatigue. At pressures higher than four PSI, the flight suit became more rigid, but Diane had no choice when presented with the option between risking nitrogen-induced bends and exerting a little more effort to move. In another fifteen minutes she planned to lower it to four psi to extend the life her PLSS.

She lowered a sun visor over the helmet before reaching for the hatch actuator lock lever and turning it 180 degrees. She pulled the D-shaped door toward her a few inches and then rotated it up until it rested with the low-pressure side facing the airlock ceiling.

“What did you say?” asked Jake Cohen, slowly turning toward the blond-headed EECOM, the Electrical, Environmental, and Consumables Systems Engineer.

“S-band telemetry shows zero pressurization inside the airlock, sir.”

“Dammit!”

“No, sir. You don’t understand. The pressure didn’t leak out. It was intentionally bled out by someone inside the airlock. My data is also showing an opened hatch to the payload bay. Someone up there just started an EVA.”

“And we can’t talk to the astronaut?”

“I’m afraid not, sir. All we can do is read the telemetry data on S-band.”

“Damn. I wish that K-band antenna was there,” said Cohen. In reality, Endeavour had given up the K-band antenna to accommodate a second RMS manipulator arm. The K-band antenna could have allowed an alternate communications channel between the orbiter and Houston Control after the S-band antenna was damaged during the laser shoot-out.

Jake Cohen grabbed the phone to update his superiors. Just thirty minutes ago he had gotten word from Andrews Air Force base that a squadron of F-22s armed with ANSAT — antisatellite — missiles was standing by waiting for the order to shoot down the station before the terrorist regained control of the warheads. Now maybe there was a chance that the station could still be salvaged if the surviving astronauts could reach the ISS in time.