Shoot for the Moon

by James Donovan

  “Flight,” Bales said, “we’re out on our radial velocity—we’re halfway to our abort limits. I don’t know what’s caused it, but I’m going to keep watching it.” (Bales would later find out that the tunnel’s unvented air had combined with thruster burns and other variables to add a bit of movement to Eagle at undocking and increased its velocity—“like popping a cork,” as Kranz would put it later—just enough to make a difference down the flight path.) Bales was worried, and with good reason—what if it was a guidance-system problem? It might get worse. His nightmare might even happen—he would have to call an abort. He had quit smoking a few months ago after an X-ray had shown a shadow in his lung, and now he fleetingly wished he hadn’t.

  But after thirty seconds, he determined that it wasn’t a guidance-system issue but a navigation problem. It was holding steady, though that meant a new problem: Eagle would be landing about three miles farther downrange than planned. But at least he wouldn’t have to call an abort.

  Bales relaxed a bit. It looked like his problem was over. He turned to Greene on his left, busy recomputing potential abort modes, and said, “We’re in great shape.”

  Four minutes later, at 4:05 p.m., Eagle’s descent engine roared to life at 10 percent power for twenty-six seconds to settle the fuel in the tanks, then powered up close to full throttle. Facedown and feet forward, the two astronauts could feel the brake through their boots as their speed and their altitude began decreasing. While Aldrin kept his eyes glued to the computer display and the other gauges, Armstrong watched the features below as they sped over the brownish-gray lunar surface—craters, hills, ridges, and cracks, their long shadows stretching westward before the rising sun. When they passed one called Boot Hill, he said, “Our position checks downrange show us to be a little long.” That corroborated what Bales had told Kranz.

  “We confirm that,” Bales said.

  “Rog,” said Kranz. The far western end of the targeted landing area, he knew, was rougher terrain. Landing would be more difficult for the fragile LM.

  A minute later, he went around the room polling on whether to continue powered descent. When he got to his guidance officer, Bales shouted, “Go!”

  Kranz chuckled, but it relieved some of the tension.

  Duke said, “You are go to continue powered descent.”

  At forty thousand feet, there was lots of static on the radio as Armstrong used his right-hand controller to roll over to windows-up, the astronauts’ feet still forward. The Earth came into view, and the landing radar antenna, now pointing down at the moon, began acquiring the velocity and altitude the computer needed to calculate rate of descent. As it continued to descend, Eagle swayed left and right every few seconds as the engine’s fuel sloshed back and forth.

  Five seconds later, a warbling alarm sounded in their headsets, and both Armstrong and Aldrin looked down at the computer display between them to see a yellow caution light.

  “Program alarm,” Armstrong said with some urgency, and Aldrin punched in a command to ask the computer to define the problem. They both looked down and saw 1202 on the digital readout.

  “It’s a twelve-oh-two,” said Armstrong. He and Aldrin looked at each other. Neither of them had heard of this alarm. They could probably find it in the book they’d brought along, but there wasn’t a spare second for that. They were trying to land a strange spacecraft that had never landed before on an alien world no human had ever touched, and in a low-gravity vacuum. Was the computer going to die on them?

  Duke, flustered, said, “Twelve—twelve-oh-two alarm,” and looked toward Bales. A silence of several seconds followed. “It’s the same one we had in training,” Duke said on the flight director’s loop.

  In Mission Control, more than one heart skipped a beat. This was the alarm that had caused Bales to call an abort two weeks before. It meant that the computer was being overloaded with data—the unnecessary rendezvous radar that had been turned on added just enough to kick its computational load over 100 percent—and it was going to ignore that secondary task, reboot, and restart selected programs where they had been before the reboot. In other words, it would continue with more important tasks, as it had been programmed to do. The simple but sturdy rope-core memory assembled by the little-old-ladies method was doing its job, but no one in Mission Control knew that. The radar had been on during simulations with no problems.

  Bales had been busy assessing the fresh radar telemetry when the 1202 sounded. He said, “Stand by,” and reached for his notebook. Garman had made him a copy of his cheat sheet, and Bales had stuck it in there. Next to him, Paules said, “That’s like the one we had in the sim.”

  To Garman, on the dedicated GUIDO loop that only the two of them shared, Bales said, “What’s that?”

  Garman had seen the alarm appear on his screen seconds after it sounded—the time it took the LM telemetry to reach Earth—and he was already looking at the cheat sheet under the Plexiglas on his console. His back room was on a dedicated, open line to a roomful of engineers at MIT, but he wasn’t sure they knew, and he didn’t need them anyway. He told Bales, slowly and calmly, “It’s executive overflow. If it does not occur again, we’re fine…that has not occurred again—okay, we’re go. Continue.”

  On the air-to-ground loop, Armstrong asked, as insistently as anyone had ever heard him, “Give us a reading on that twelve-oh-two program alarm.” Usually Aldrin talked to Mission Control about such things, since Armstrong’s attention was on the window in front of him and the ground coming toward them. But Armstrong’s eyes were now fixed on the instrument panel. To the right of Armstrong’s window lay the red ABORT and ABORT STAGE buttons.

  Bales said, “We’re…we’re go on that, Flight.” Go in this case meant “nothing to worry about.”

  Kranz said, “We’re go on that alarm?”

  Kranz was about to accept Bales’s decision, but Duke had heard it and he didn’t wait for Flight to confirm, as CapComs usually did. As a pilot, he knew the men in the LM were thinking abort, and they needed an answer fast, so twenty-one seconds after Armstrong first mentioned the alarm, he said, “Roger. We got you—we’re go on that alarm.”

  “It’s—if it doesn’t recur, we’re go,” said Bales.

  Garman, on the GUIDO loop, reassured him. “If it’s continuous, that makes it a no-go. If it reoccurs”—he meant with at least several seconds in between—“we’re fine.” Sitting next to him was thirty-seven-year-old Russ Larson, MIT’s representative to the LM crews, almost a foot shorter than Garman. He didn’t know what the alarms were and was too scared to speak. He could only give Garman a weak thumbs-up.

  Someone in a backroom loop said, “Hey, this is just like a simulation,” and for some reason, everyone relaxed a bit. The computer was still doing its job of firing thruster jets and navigating, and it appeared the problem was gone.

  Fifteen seconds later, the same 1202 alarm sounded with another yellow light.

  On the GUIDO loop, Garman said, “Tell ’em to leave it alone and we’ll monitor it, okay?”

  Bales passed the word along, as did Duke.

  Aldrin was worried about further overloading the computer, so he stopped asking it for landing radar data. He had begun calling out critical info: velocity rate and descent speed in feet per second, and altitude. The engine throttled down—a good sign; it meant the computer was still working—and at twenty-one thousand feet and seven minutes into the descent, Eagle began to pitch over so the astronauts faced forward, standing again. Forty seconds later, when the craft was at sixteen thousand feet, the lunar surface began to creep into the bottom of Armstrong’s window.

  Kranz said, “Everyone hang tight. Seven and a half minutes.”

  Bales told him, “The landing radar has fixed everything; the LM velocity is beautiful.” More than a minute had gone by since the last alarm, and they were receiving a clear signal. To Greene he said, “Jay, we’re in good shape now, babe.”

  The LM was dropping quickly, at a hundred feet p
er second, and at almost nine minutes, it was five thousand feet above the surface. To test his manual controls, Armstrong checked the right-hand controller, which adjusted attitude; he moved the toggle switch from auto to attitude hold, tested yaw and pitch, and pushed it back to auto. He knew he’d need it soon.

  Kranz polled the room for the last time, now asking whether or not to land. Bales gave another resounding “Go!” At three thousand feet, Duke gave them a go for landing, and ten seconds later, there was a familiar sound.

  Aldrin said, “Program alarm,” paused, then said, “Twelve-oh-one.”

  Both Garman and Bales were all over it; it was a similar alarm. “Same type,” said Bales. “We’re go, Flight.”

  Duke didn’t bother waiting for confirmation. “We’re go. Same type, we’re go.”

  The alarms had caused Armstrong and Aldrin to spend too much time monitoring gauges. When Armstrong was finally able to devote his full attention to the triangular window in front of him, he realized he’d lost track of the landmarks he had studied at such great length. At two thousand feet, he could see a crater coming up. He asked Aldrin for a reading for the landing point.

  Aldrin punched the question into the computer, then read the answer. “Forty-seven degrees.”

  Both panes of Armstrong’s window were inscribed with a grid that was calibrated to his height and eye level in degrees, and it showed where the computer, which didn’t know the LM was going long, planned to land them. He moved his head to align the grids and looked out, about a mile or so away. “That’s not a bad-looking area,” he said at a thousand feet.

  He changed his mind a few seconds later. The computer was about to land them on the side of a crater about the size of a football stadium with boulders as big as cars surrounding it. For a second, Armstrong considered trying to land there—maybe he could find an open, level space just short of the crater where the slope wasn’t more than fifteen degrees, roughly the maximum safe angle estimated for a successful ascent. A much sharper angle and the LM might tip over; even in the one-sixth gravity of the moon, it would be impossible to right. But they were moving too fast to try landing.

  “Twelve-oh-two alarm,” said Aldrin.

  “Roger, no sweat,” Garman said to Bales.

  “Roger, twelve-oh-two, we copy it,” said Duke.

  Aldrin, the Mechanical Man, began to coolly call out the critical data Armstrong needed: rate of descent, in feet per second, and altitude. Seconds later they were at six hundred feet. Another 1202 alarm. Everyone ignored it.

  There was an old saying among pilots: When in doubt, land long—what was up ahead of you was easier to see than what was under you. Armstrong decided to do that.

  He said, “I’m going to…” but he didn’t need to finish. Everyone knew he was taking over manual control. He quickly slowed the descent to almost zero by switching the autopilot from auto to attitude hold—that would also ease the computational burden and prevent further program alarms. The computer was still involved, but he would be telling it what to do; he, not the computer, would now control the landing. Armstrong pitched Eagle forward to almost level and guided it over the rim of the large crater and its boulder field, bending the trajectory slightly left to avoid a particularly large rock and then resuming his original course. The LM flew better than he had expected; all those hours in the unforgiving LLTV had been worth it.

  The ground was getting closer—five hundred feet below them. They were moving faster than they ever had at this point in a sim and still slowly descending over what looked like the lifeless bed of an ancient lake.

  In Mission Control, a controller reported, “We’re on attitude hold,” and Duke said, “Attitude hold.”

  Slayton slapped his arm and said, “Shut up, Charlie, let ’em land.”

  Duke said, “Yes, sir,” then said to Kranz, “I think we better be quiet, Flight.”

  “Rog,” said Kranz. He told his team, “Okay, the only callouts from now on will be fuel.”

  Aldrin mentioned the forward velocity for the first time: “Fifty-eight forward”—about forty miles an hour.

  “No problem,” Armstrong said calmly, though his heartbeat had doubled to a hundred and fifty. With his right hand, he carefully tilted Eagle back to allow the rocket engine to slow their velocity, and with his left, he toggled the controller switch, one click at a time, adjusting his rate of descent by one foot per second. Between the noise of the rocket engine below them and the frequent cracks made by the sixteen small thrusters arrayed around the exterior, it was loud in the cabin. Up ahead, he could see a relatively smooth area between some large craters and a boulder field. It wasn’t perfect, but it would have to do.

  He said, “How’s the fuel?” The LM descent engine didn’t carry more than about twelve minutes’ worth.

  “Eight percent,” said Aldrin.

  “Okay. Here’s a—looks like a good area here.”

  Aldrin shot a quick glance out his window and saw the LM’s shadow on the ground beneath them and ahead—the sun was low behind them. “I got the shadow out there,” he said.

  They were at two hundred feet and had slowed to thirteen miles an hour. They scooted over a small crater.

  By this time in every simulation, the LM had touched down, crashed, or aborted. Their new landing site wasn’t even in view, and fuel was getting low. Propellant slosh in the tank meant that an accurate fuel-level reading was impossible. Like seafaring explorers centuries before, they were now in terra incognita. They continued skimming over the brightly lit gray surface a hundred feet below them. Another 1202 alarm sounded.

  Duke said, “You’re GO,” though they knew that already.

  Duke knew Armstrong had no intention of aborting; he was going to try to land, alarms or not, just like he’d told them he would in all those planning sessions. No one on the ground knew why Eagle hadn’t landed yet—it should have—but they all knew there had to be a good reason. A display on one of the front screens showed the plot of the expected trajectory; Eagle had followed this graph closely at first, but not anymore.

  Aldrin looked at the fuel reading—a red light had just come on. “Five percent,” he said. “Quantity light.” If they were still aloft in ninety seconds, they were supposed to make a decision: land within twenty seconds or abort. Aldrin was concerned, but there was nothing he could do. The last thing he wanted to do was disturb his commander’s concentration. He continued to read out numbers—attitude and rate-of-descent speed and forward velocity in feet per second. “Sixty feet, down two and a half…two forward…two forward…that’s good.”

  A red low-fuel-level light had flashed on Bob Carlton’s console also. He had started a stopwatch and was now counting down the seconds before the Eagle ran out of fuel. “Sixty-five, sixty-four, sixty-three, sixty-two, sixty-one, sixty…”

  Duke said, “Sixty seconds”—one minute until the mandatory abort-or-land decision.

  The ground was close now. They had entered the dead man’s zone, an old helicopter term meaning that if they tried to abort at this point, their downward velocity would crash them into the ground before they could ignite the ascent engine. Armstrong wanted to maintain a slight forward speed so they wouldn’t fall into a hole that he couldn’t see under or behind them.

  Aldrin said, “Forty feet, down two and a half. Picking up some dust…thirty feet, two and a half down. Faint shadow.”

  Armstrong had noticed it too. A sheet of dust dislodged by the engine exhaust flared up from the surface and made it almost impossible for him to judge his rate of descent or determine where the ground was. He could see some rocks ahead through the slowly moving dust, and he tried to base his velocity decisions on that.

  Everyone in Mission Control was silent except for Carlton, who called out, “Thirty seconds,” and Duke said, “Thirty seconds,” but Armstrong was coming down and fuel was not a factor for him anymore; if the engine quit, they would just fall to the ground. He figured the compressible landing gear could absorb a fal
l from thirty or forty feet.

  “Drifting forward just a little bit—that’s good,” said Aldrin.

  They were moving left when a blue light flashed on the control panel: LUNAR CONTACT. One of the probes had touched the surface.

  Aldrin said, “Contact light.”

  Armstrong said, “Shutdown,” and quickly turned off the engine—the back pressure could cause an explosion.

  Aldrin said, “Okay. Engine stop.”

  Neither of them felt the touchdown, but they had stopped moving. Armstrong watched, fascinated, as dust particles continued to race out to the horizon, which appeared surprisingly close, and then disappeared over it. Except for the glycol pumps, it was silent.

  At 2:17:39 p.m. Houston time, Armstrong and Aldrin grinned at each other and shook hands firmly, then checked to make sure that everything, especially the engine arming control, was off.

  Duke half collapsed onto his console in relief and said, “We copy you down, Eagle.”

  “Engine arm is off,” said Armstrong. “Houston, uh…” He waited a couple of seconds, and then with added spirit, he said, “Tranquility Base here. The Eagle has landed.”

  In Mission Control, when Armstrong shut down the engine, everyone started to breathe again. Carlton looked at his stopwatch. It said eighteen seconds—meaning eighteen seconds of fuel left, roughly, though no one could know for sure. Later it would be determined that they had as much as forty-five seconds left, but with fuel slosh, it was hard to tell at the moment.

  Steve Bales had just started his abort procedures when he heard “Contact light.” Now he was puzzled—Tranquility Base? In every one of the hundreds of sims they’d done, he’d never heard that call sign. Then he thought: What a wonderful name.

  The only person Armstrong and Aldrin had mentioned the base name to was Charlie Duke. Now he said, “Roger, Twan…Tranquility. We copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.”