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NSF Contest Winner

Letting Go

Written by David Walton

I never wanted Rachel to go into space. Space was my passion, but for my daughter, I wanted a normal American life: Barbie dolls and pony rides, makeup and boys, the senior prom. A good college, a good career, marriage, kids. Only I wasn't there, most of the time, to see it happen. When she played Mary in her Sunday School pageant, I was on the ISS. When she graduated high school, I was on the moon, already starting the Gravity Train project. But there must be some truth to the argument for nature over nurture, because despite my long absences, she took after me instead of her mother. Joined the academy, earned her pin, and followed me to the moon.

The morning of the accident, we were all ready to celebrate. We gathered in the control room, Rachel holding my hand, Commander André Gretzsin, Jr. beside her, and the rest of the crew pressed in close behind. On screen, a Herrenknecht Tunnel Boring Machine named Big Betsy churned through the lunar rock at the bottom of The Hole, as it had been doing without stop for almost eight years. Today was different, though. Today, Big Betsy would finally reach the end of her task. No one dared to speak. The only sound was the bass growl of the machine, transmitted back to us through the video feed.

The Hole was two meters wide and more than three thousand kilometers deep, stretching from Mare Serenitatis straight down to the core. On the other side of the Moon, starting at Farside Station and plunging nearly as far, was the dig known affectionately as The Other Hole. The boring machine on that side had been redirected the day before to get it out of the way. As we watched, the last bit of rock tumbled forward in a loose spray as Big Betsy connected the two holes into one long tunnel, the longest ever dug, nearly seven thousand kilometers long.

We broke into cheers. On another video display, the team at Farside danced and hugged each other. It was finished. We'd actually done it.

Four hundred years ago, Robert Hooke proposed the perfect transportation system to Isaac Newton: a straight tunnel through the Earth from any two points on its surface. A frictionless sled dropped down the hole at one end would arrive at the other side forty-two minutes later with perfect conservation of energy. For Hooke and Newton, it was a thought experiment—a puzzle on which to apply the new laws of geometry and gravitation. On the Moon, however, with modern drilling techniques and no atmosphere to cause friction, their idea had become a reality. In a few months, when the train capsules were completed and put into service, a thousand pounds of helium-3 a day would be scooped up from the vast deposits around Farside and transported by gravity train to the near side.

"So there it is," said Rachel. "A really, really deep hole."

I snorted. "That's all we hear from the media." The project had required almost twice the originally planned budget, and most of their news coverage revolved around how much money the government was sinking into a very deep hole. "One of those helium-3 capsules will provide enough fusion energy to power New York for a year. We're going to solve the world's energy crisis, and all they can talk about is the Guinness Book of World Records."

Rachel squeezed my hand. "When I was little, I was always out digging holes in the backyard."

I smiled, but it gave me a pang for her to mention her childhood. The childhood I had missed. "Digging a hole to China?"

"Digging a hole to anywhere, as long as it wasn't home."

"You wanted to get away that badly?"

"Mostly I just wanted to be with you."

"You and Mom . . ." I began, but she put a finger on my mouth.

"Let it go, Dad. We were too different. Not your fault."

Her blond hair was cropped close, a concession to the hardships of space, and her face showed the fluid swelling typical of long stints in low gravity. She was my height, slender, strong, and independent. She was different than her mother, all right. But she wasn't what I had wanted her to be.

"Dad?"

Her tone worried me. "What's wrong?"

"Nothing. I wanted to pile on some more good news."

Something was wrong. Rachel was never hesitant.

"André and I are going to be married."

I pressed my lips together. She knew my opinion of astronauts and marriage. That's why she chose that moment to tell me. "What happened to 'single forever'?"

"I changed my mind."

I glanced around the control room and spotted André at his terminal, watching us.

"What do you want, my blessing or something?"

"I just want you to be happy for us."

"I probably won't make it to the wedding."

"Sure you will. We'll have it as soon as we get home."

"I might have to stay here longer than you, make sure everything keeps running."

"Then we'll wait. You have to come back to Earth eventually."

I shook my head. Against all odds, she'd beaten her mother's influence and made a career for herself. Now she wanted to throw it away for domestic life?

But she knew what I thought; I didn't have to say it. Back to work. Big Betsy had to be redirected to drill into the side of the tunnel, where she would be left forever—it wasn't worth the energy to pull her back to the surface. The other boring machine was already snug in its own little grave, ten meters into the rock.

André must have snuck up behind me, because I heard him say, "I'll take good care of her, Frank."

I wanted to hit him, but I kept my voice soft. "You're on the short list for Mars, André. She's not. What are you going to do, leave her in a Florida apartment with a baby in her belly while you go away for seven years?"

André looked angry, but he didn't snap back.

Rachel said, "Dad . . ."

"Forget it. It's your life. I have work and so do you."

I sat down and ignored them. Eventually they left.

****

An hour later, I watched her on screen as she worked inside Capsule A. Our command center partially encircled the Hole in a rough U-shape, inside of which were the oxygen tanks for the complex, fuel and extra cutting blades for the Tunnel Boring Machines, construction materials, and in the center, the capsule itself. It was held in place above the chasm of the Hole by the electromagnetic capture system, but for safety, a series of bolts prevented accidental release. She was inside, suited up, spraying the capsule with insulator before its virgin drop the next day. She barely fit; at just shy of two meters wide, the capsule had been designed for cargo, not human passengers.

I watched her work, confident, at ease in a spacesuit, skilled at her task. I had been unfair. André was a talented spacer, a third-generation astronaut whose grandfather had been on the Mir. He was stable, trustworthy, a great commander. He had lost his own father in a training accident when he was young; he knew the risks of space. I knew my reaction had more to do with guilt about my own failed marriage than about him, but I still couldn't see past it. A life in space and a family just didn't fit together. Even so, I owed her an apology. I reached for the comm.

Then it happened. The video feed dropped to static, and I felt a deep vibration in the floor. The moment froze, like a shuttle when the last booster drops away and the battering five-G ascent becomes instantly silent and perfectly still. I ran to the windows, my body sluggish, underwater. My eyes met André's across the room, and we both knew. An explosion. Disaster.

We looked out and saw the impossible: a fire on the Moon. The capsule platform was engulfed in flames. It would be months before we found out what happened—lunar dust had fouled a valve, causing pressure to build up. The resulting explosion had doused the platform with burning fuel and pierced an oxygen tank at the same time, providing the fire with a steady supply of fresh oxygen to keep it alight. At the time, all we knew was that Rachel was in trouble.

Crew members packed the airlock, frantically suiting up for a rescue attempt, but I could see they would be too late. I rushed back to the comm.

"Rachel? Are you there?"

"Roger that, Control," came her calm voice, just as she'd been trained to react in a crisis. "The temperature is rising fast in here. Can I get out the hatch?"

"Negative. Egress is completely blocked."

"Can they put it out?"

The two men who had reached the fire with extinguishers backed away, unable to get any closer.

"Not in time."

My mind raced, trying to keep the horror out so I could think clearly. It wasn't my daughter; it was a problem to be solved. And then the solution was obvious.

"Drop her!"

André turned from the window to stare at me.

"Come on, help me. Release the bolts and drop the capsule."

André shook his head. "Big Betsy hasn't cleared the tunnel yet. She'll die."

"She's dying right now; that fire's going to cook her before anyone can stop it. It's her only chance. Do it!"

We kicked chairs out of the way and grabbed our consoles. It didn't take long. The bolts retracted and the capsule, released, plummeted into the Hole.

André grabbed the comm, thumbed the global override, and bellowed into it. "I need every hand back to Control right now. The capsule is in the Hole. Repeat, everyone back to the control room at once."

He turned back to me. "Big Betsy has twenty minutes to get out of the way."

****

The Herrenknecht Tunnel Boring Machines were the fastest ever built, advertised to excavate at a rate of a kilometer a day. Their real progress was slower, of course, because worn drill bits had to be changed regularly, and dirt had to be removed. The boring machines used to dig the Chunnel under the English Channel pulled out eight million cubic meters of dirt, which was used to reclaim 90 acres of oceanfront property near Folkestone, creating a public park frequented by children and picnickers. On the moon, the removed dirt was