Unfortunately, to keep hydrogen liquid, it had to be kept cold. In fact, the temperature had to be kept to about minus four hundred twenty-three degrees Fahrenheit. To do this, the huge hydrogen tanks in the EDS were kept wrapped in the best thermal insulators known and placed in the vehicle so as to minimize the heat they might receive from the sun and that reflecting back into space from the Earth. It was, in effect, a large thermos bottle in orbit. It was also an imperfect thermos bottle; some heat inevitably would always get through to warm up the hydrogen. As the volatile gas warmed, it boiled and evaporated and then vented into space. Hence the phrase “boil-off.”
Engineers designed the EDS tanks and propulsion system to have enough liquid-hydrogen propellant remaining—after boil-off—to complete the mission even if the craft had to remain in orbit for a few days before beginning its trip to the Moon. If its time in orbit exceeded the design limit, then there would simply not be enough fuel remaining to complete the mission. Since there had been some minor glitches before this one, the allowable time in Earth orbit was close to being over, and a further delay would mean that the burn to send the Orion to the Moon would not happen—at least not on this test flight.
“Oh, well,” Bill Stetson responded with an audible sigh as he readjusted his headset. He then straightened himself in the seat and barked, “Release the automatic docking system to manual control. Give me real-time data from the laser ranger and don’t give me any more data from the damned GPS!” This, too, they’d practiced in training. A manual docking was something the astronaut corps had insisted upon since the Shuttle-Mir program of the 1990s. This was what the pilot and mission commander lived for. In an instant, Stetson decided to assume control of the Orion instead of asking his pilot, Charles Leonard, to do so. It was his call and he made it. Leonard heard the call and, though disappointed, accepted the decision and made himself ready to step in should he have to do so.
Switching views on the monitor in front of him and seeing the requested data feeds appear on the secondary monitor to his right, Stetson prepared to take manual control of the Orion. Forgetting about the paperwork that would be required should he be successful, and the probable reprimand should he fail, Stetson gave the order to release the vehicle to manual control.
“Alright, give her to me,” he said.
To a detached observer, it would have appeared that Bill Stetson was beginning to play a video game. With a controller that looked like the technological cousin of a PlayStation game controller and an LCD screen with a simulated 3-D rendering of both the Orion and the EDS, he assumed manual control.
At first, he saw no discernible effect from his efforts. He’d begun by firing the thrusters on the Orion that were responsible for making a rendezvous possible. But he didn’t fire them to accelerate the craft; rather, the opposing sets of thrusters were used to slow it down. Newton’s laws are unforgiving. Every action has an equal and opposite reaction. To speed something up, you fire rocket engines. To slow that same something down, you fire rocket engines that point in the opposite direction. And it takes the same force to accelerate to fifteen feet per second as it does to slow down by fifteen feet per second.
“You should be seeing something. The propellant in the tanks is starting to drop rapidly,” Stubborn Stu said calmly. “You still have plenty remaining, but I’m definitely seeing it.” He, like just about everyone else in the room, was starting to perspire. It was a stereotypically hot Houston afternoon in a room with stereotypically cold Houston air-conditioning doing nothing to prevent the perspiration from coming. It just made the sweat feel uncomfortably cold.
The sweat starting to bead on Bill’s forehead glistened in the control-room lighting. He kept a watch on the laser-ranger data, and finally the velocity numbers began to decrease. The velocity dropped from an excess of five meters per second to four. Then to three and finally to a closure rate that should permit safe docking. This happened not a minute too soon—as Stetson fought to bring the closure velocity down, the distance between the Orion and the EDS continued to dwindle. They were now only a hundred meters away from one another and in desperate need of fine guidance for the final rendezvous. This, too, was a maneuver that the team in mission control had practiced manually, and their training not only took over for these last few minutes of the rendezvous, but it alleviated the stress and allowed the heart rates of the console techs to fall back to normal.
“We have manual docking in three…two…one.” Marianne Thomas provided the countdown. Bill could tell from the tone in her voice that she was grateful he had overcome the problem and that it wasn’t something she’d done. He figured that the engineer already was beginning the mental construction of a fault tree that would help the mission-review team find out why the automated system had failed and why the GPS data was suddenly blank.
“Phew,” Stetson said, relieved at completing the docking maneuver successfully. He then declared, “We’re not finished here yet, people. Need I remind you, we’ve got a vehicle that needs to be checked out and sent on its way to the Moon. No dinner and bar just yet.” And he knew that he was correct. If nothing else went wrong, the flight was supposed to continue to the Moon, with the EDS lighting its engines to escape Earth’s gravity in just a few hours.
The two concurrent failures still needed to be explained and corrected. While the GPS measurements would be useless at the Moon—which had no Global Positioning System satellites—the onboard computer that was supposed to make sense of the laser-ranging data would be used again when the Altair lunar lander returned from the surface of the Moon to rendezvous and dock with the Orion in lunar orbit, allowing the crew to transfer back to the Orion for their trip home. Yes, this was an unmanned test flight, but the systems nonetheless had to work or the launch of the actual mission would be postponed indefinitely until the problem was resolved. The public and political pressure was mounting to kill the space program, and having to scrub so close to launch could be a public-relations nightmare. Bill hoped to circumvent all that.
The decision to continue the mission or not would have to be made within hours or the liquid-hydrogen supply would boil away uselessly into space. That would give the ground-support team at least a few days to troubleshoot the automated rendezvous and docking system, and its computer and software, to find the source of the problem and hopefully fix it. At least, that’s the logic Stetson was using when he made the decision that only he could make.
“All right, everyone, we’re go for Lunar Orbit Insertion unless and until I say otherwise. We’ll get this problem fixed and patched before it’s needed again. Let’s stay the course.” In his unflappable way, which was one of the reasons he had been selected to be the commander of the first human lunar return flight, Stetson both committed the mission to the next phase and reassured all in the room of the can-do attitude that was so crucial to past mission successes, had been missing at NASA for decades, and, while on his watch, was absolutely crucial to the current mission—his mission. Bill was going to go to the Moon or bust.
Chapter 2
The cause of the rendezvous and docking failure was still unknown, but virtually every member of the team that developed the system and its flight computer were called in to begin working on understanding the failure and figuring out how to fix it. Rocket scientists and engineers in Houston, Texas, and Huntsville, Alabama, found out that they wouldn’t be going home on time. A flurry of cell-phone calls, e-mails, and text messages to spouses or significant others went out explaining that they wouldn’t be home for dinner. Take-out pizza would be the most common meal of the day.