Back to the Moon: Chapter One

    As famously depicted in the movie 2001: A Space Odyssey, the movements of objects in space did appear to be choreographed like those of dancers. With grace, precision, and painfully slow forward motion, the two-hundred-eighty-two-thousand-pound Earth Departure Stage, or EDS, and the four-person Orion capsule moved closer and closer to each other. From the Orion capsule’s point of view, it was moving toward the EDS, with its attitude-control thrusters firing in quick “bang bang” succession. As the distance between the two spacecraft decreased from kilometers to mere hundreds of meters, the glorious blue and white Earth moved quickly beneath them only a hundred or so miles away.

    The latest test flights of the vehicles that would hopefully carry people back to the Moon for the first time in over fifty years moved toward completion. The present tests were an important step even though no people were onboard either of the vehicles.

    The vehicles were on autopilot, testing the “new and improved” automated docking and rendezvous system that NASA had been working on since the space-shuttle days. Gone was the day of the astronaut “rocket jockey” controlling every spacecraft movement with a throttle and stick. Of course, the “rocket jockeys” themselves didn’t agree with the move, and the general public typically liked the notion of the superheroic space-pilot astronauts. However, the guys with the software had won the technical arguments and determined that having the pilot “out of the loop” was by far a safer approach. Or so their calculations indicated.

    The massive aluminum-and-composite EDS had been launched just hours previously by the mighty Ares V rocket. Measuring over ninety feet long and containing enough fuel to carry four people, a lunar lander, and all the supplies needed for a week’s stay on the Moon, the EDS appeared to be dead, floating effortlessly two hundred and ten kilometers above the Earth. The over-one-hundred-forty-ton behemoth moved around the Earth at nearly seventeen thousand miles per hour. The Orion was closing in on it, moving with about the same speed, adding only enough velocity to catch up with the EDS in order for the two spacecraft to dock.

    And the distance was closing—rapidly. Too rapidly. The first warning bell sounded in mission control at 2:58 p.m., local time. Nobody was particularly alarmed by the bell.

    “Bill, we’ve got an anomaly with the Orion’s close rate on the EDS,” Marianne Thomas said calmly from her console near the back right corner of Constellation Mission Control at the Johnson Space Center in Houston. The anomaly had been simulated in training, but she hadn’t expected it to happen during the test. But that was why they trained. “Orion’s laser ranging indicates they’re closing faster than programmed and faster than the onboard computer says it’s going.” There was only objectivity in her voice and not a trace of the anxiety that she was starting to experience in her gut.

    “Roger that,” Mission Commander and Blue Team’s Flight Controller Bill Stetson responded automatically—again, thanks to the training. “Do we have confirmation of the closure rate from GPS?”

    The onboard differential GPS system was supposed to be able to resolve the relative positions of the two spacecraft and calculate relative motion based on successive position measurements. Stetson was set to command the next flight—the one that would actually carry people to the Moon—and was in charge of this portion of the final flight test. Up to this point, everything had gone fairly smoothly, and this was just fine with Bill Stetson.

    “Bill…” Thomas hesitated, a pause that was noticed by all in the room, including Stetson. “Looks like we have no data from GPS.” Her eyes were scanning the display in front of her, desperately trying to find out why there was no data and simultaneously not believing that she would be the one with the flight anomaly. She pursed her lips and repeated her last words for clarity. “We have no data from GPS. I’m trying to find out why.”

    Throughout mission control, those on console were verifying and reverifying the data scrolling across their screens, hoping to have some bit of information to provide that would help all in the room understand the situation. Only a minute had passed since Thomas’ announcement, but to those responsible for the success of the test flight, it seemed like an eternity. Finally, the technician monitoring the Orion’s propulsion system saw something and spoke up.

    “Orion propellant is showing lower than predicted,” the console tech said. He then hesitated a moment before continuing. “It’s not enough to trigger an alert, but it is lower than it should be.” The technician, known to his comrades and friends as “Stubborn Stu” due to his alleged inflexibility in virtually all things, might also have been called “Meticulous Stu” for his attention to detail. Whatever the nickname might have been, when he spoke, his colleagues always listened.

    “Roger that, Stu.” Bill thought about the data briefly. He knew that less propellant in the tank could mean that more propellant was being used than predicted. And that could account for the Orion moving too fast. If the engines were burning for even a fraction of a second too long, then they would consume more propellant. And if they were consuming too much propellant, then the spacecraft was accelerating faster than expected. That wouldn’t be good.

    Of course, there could also be other explanations. In this case, the specific reason why the propellant was low was not of immediate concern. But Bill was certain that the fact the propellant level was too low was all the confirmation he needed to conclude what his next step ought to be.

    “Marianne, what rate does laser tell us we’re dealing with here?”

    “Hold on.” Thomas tapped some keys on her console without hesitation and then replied. “According to laser, we now have a delta-vee excess of slightly over five meters per second and accelerating. No confirmation from GPS.”

    “Sheesh,” Bill muttered to himself. Five meters per second was just a little more than fifteen feet per second. All in the room understood the implications. The Orion and EDS were designed to soft dock with one another. In other words, their rate of closure would gradually decrease to only a fraction of a meter per second when they finally made contact. If they were to collide moving tens of feet per second, not only would the docking maneuver fail but it might result in a crash, with the loss of both the Orion and the EDS being a real possibility. And that was simply not acceptable to NASA, mission control, or Bill Stetson.

    “Abort options?” Stetson hated to ask the question, but mission procedures gave him no option. A safe abort and potential retry in a few orbits was simply the right course of action to consider. Lives were not at stake, but billions of dollars and months, perhaps years, of schedule were. And Bill Stetson didn’t want a test-flight failure to set back the date for his flight to the Moon. Who knew how the press would handle another NASA failure? The evening news report of a disaster in space might be enough to halt the Moon mission altogether.

    The technician who reported the excess propellant usage had on his screen an algorithm that constantly told him what propellant would be required to perform an abort and an estimate of the trajectory and time required to recover from the abort so that another attempt could be made. Bill knew that the console tech was ready for his question.

    “Well, Bill,” Stubborn Stu started, “if laser ranging data is correct and we have to perform a burn to take out that velocity and then fly around a few orbits to try again, we will be at the minimum propellant margin for the rendezvous. But it still won’t meet mission-success criteria. The EDS will have been on-station too long. Propellant boil-off will exceed TLI commit.”

    Though never actually uttered, virtually everyone in the room heard the expletive that Stetson thought to himself. Bill pulled his headset free for a second and adjusted his thinning hair while making a motorboat sound with his lips. Not being able to do a TLI, or Trans-Lunar Injection, burn of the rocket engines would mean not going to the Moon. The longer the EDS had to wait, the more propellant would evaporate—reducing the total burn-time possible for the engine. They had to fire before too much had boiled off.

    The EDS was powered by one of the most energetic rocket fuels known—liquid hydrogen. When combined with an oxidizer, in this case the ultimate oxidizer, liquid oxygen, the combustion produced the rocket thrust that would propel the EDS toward the Moon. It was these same propellants that powered the three main engines of the old space shuttle, producing much of the cloud of steam that was the hallmark of a successful launch.

    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.