Astrotwins — Project Blastoff

by Mark Kelly

  “I’ve been working on the control program, but I still have a lot of math to learn about orbital mechanics,” Howard said. “One thing I realized is that we’ll save fuel if we launch directly to the east. Earth rotates eastward at roughly 1,000 mph, which means that effectively, the spaceship on the launchpad is traveling that fast, too.”

  “And so are we, for that matter,” said Barry.

  Howard thought for a moment and nodded. “Yes, I suppose that’s true.”

  “Weird,” said Mark.

  “Anyway, that is effectively 1,000 mph worth of fuel we don’t have to use. Saving fuel saves weight, which in turn saves fuel . . . .”

  “The rocket equation,” said Jenny. And then she said something both Mark and Scott found incomprehensible: “Change in velocity equals exhaust velocity times the natural logarithm of the initial mass divided by the final mass.”

  Scott looked at his brother, and his brother said, “What?”

  “Maybe it would help if I wrote it down,” Jenny said. She pulled a pencil from her pocket and wrote on the back of a napkin:

  “Oh yeah.” Mark nodded sagely. “Sure. Now I get it. Perfectly clear.”

  “Why didn’t you just say that before?” Scott asked.

  “Sarcasm again?” Howard said. “Because she did say that before. The change in velocity equals the—”

  Mark held up his hand. “Really, Howard. Repeating it won’t help. What are you math nerds talking about?”

  Jenny’s and Howard’s expressions said: It’s so totally obvious, there is no other way to explain it. But Barry raised his hand. “I can give it a try. A Russian math teacher developed this equation. It describes the rocket’s velocity as the fuel burns up and shrinks its mass. His name was Tsiolkovsky—Zy-ol-koff-skee.”

  “Oh!” said Scott. “So it’s in Russian? No wonder we don’t understand.”

  Mark rolled his eyes. “Math is a universal language, dummy. Uh . . . , isn’t that right, Barry?”

  “More or less,” said Barry. “Now shut up—excuse me, be quiet—and I will explain. So you guys get velocity, right? It’s the speed of something in a particular direction. And that little triangle is a delta sign, which means change. So the left half of the equation is change in velocity. Are you with me so far?”

  Scott and Mark nodded.

  “So the other half of the equation is the exhaust velocity—in other words, how fast the exhaust is spewing out of the rocket’s nozzle. You multiply that times the initial mass of the rocket, which includes the fuel in the rocket, and then divide it by the final mass of the rocket, which is what’s left after the fuel has burned off. Then that number gets multiplied by the natural log function, and it equals the change in velocity—the left part of the equation.”

  A lightbulb flashed in Mark’s brain. The bulb was only about as big as a firefly, but it was definitely switched on. “So the rocket flies, and as it flies, its mass shrinks because part of its mass was fuel that has burned off in the exhaust?” Mark said. “And as the mass gets smaller, there is less fuel available but, at the same time, it takes less fuel to propel it. Is that right?”

  “Yes!” said Barry.

  “But what’s this natural log business? It sounds like it has something to do with a fireplace,” Scott asked.

  “In this case it’s a constant to describe something that changes continuously over time,” Barry said. “So the mass of the fuel is changing and affecting the velocity not just moment by moment, but also all the moments in between. The natural log is a mathematical way to describe that.”

  Mark sighed. “If you say so.”

  “It’s Tsiolkovsky who said so,” said Egg.

  “In Russian,” Scott reminded them. “But why do you want to know this again?”

  “It tells you most of what you need to know to put a rocket in space,” Egg said. “How much fuel you need, how massive your rocket and your capsule can be, and how fast you can go. It’s pretty cool.”

  By this time lunch was over, the last lemonade drop drunk and cookie crumb devoured. Grandpa Joe had listened for a while but then gone back into the house to work on today’s remodeling project, a new tile floor in the bathroom. After clearing their dishes and washing up, the kids headed back to the workshop.

  CHAPTER 20

  * * *

  Egg’s idea was that they make an inventory—a list—of all the items in the workshop, then cross-reference it with what they thought they would need. At that point, they could go back to Nando and see what additional supplies he might be able to provide.

  “We also need to inventory our skill set,” Egg said.

  Mark looked at the other kids one by one, then asked, “Does everybody else understand her all the time?”

  Egg rolled her eyes. “All I mean is, we figure out what each of us knows how to do so we know what help we’ll have to ask for. Like, Howard can program a computer. But besides that there’s going to be metal fabrication, and soldering, and wiring, and plumbing . . . and on and on.”

  “I can weld,” said Lisa.

  “You can?” Scott said. “Can you teach us?”

  Lisa looked at her toes and nodded.

  “That is so cool!” said Mark. “How does welding work, exactly?”

  Lisa thought for a second. “Basically, you’re using an arc of electricity to melt metal and make glue out of it. Then the glue sticks two pieces of metal together.”

  “Is it hard?” Egg asked.

  “It’s hard to do neatly,” said Lisa. “You have to practice a lot.”

  “Okay, welding, check,” said Egg.

  “Can I ask a question?” Lisa said.

  “Sure,” said Mark.

  “So is the secret science fair project a spacecraft?”

  Everyone laughed—even Howard. Lisa turned pink, and Egg said, “Sorry, Lisa. I guess no one officially told you that yet, huh?”

  Lisa shook her head.

  Egg explained, “It’s really only a secret from the grown-ups. We don’t want them to tell us we’re crazy or we can’t do it. Do you think we’re crazy?”

  Lisa shrugged. “Not necessarily. And I won’t tell. I’m good at keeping secrets.”

  “Unlike some people,” Scott said.

  “One thing, though,” Lisa said. “I don’t have to be an astronaut if I help out, do I? I’m claustrophobic—I don’t like squished places.”

  “You absolutely don’t have to be an astronaut,” said Scott. “There’s only room for one anyway.”

  Egg looked up. “Oh?”

  “I want to go,” said Howard.

  And Barry said, “Who made the decree that there’s only room for one?”

  “Oh, come on, you guys,” said Mark. “You’re the ones who understand the rocket equation. We’re going to have a hard enough time building and fueling a small spacecraft, let alone one that holds everybody.”

  Egg said, “You have a point, and we should probably pick according to weight. If Lisa doesn’t want to go, I’m definitely lightest.”

  “But it was Scott’s and my idea!” said Mark.

  “I didn’t mean to cause a fight,” Lisa said quietly.

  “It’s not your fault. Some people are just unreasonable,” said Mark.

  “So anyone who doesn’t agree with you is unreasonable?” Barry said.

  “That’s an unreasonable assertion,” said Howard.

  “Guys?” said Egg. “Has anybody noticed something? Now that we’re arguing, we’ve all stopped working. At this rate we’ll never get any”—she looked around, then whispered the word—“spacecraft built at all. Maybe we can put off this decision.”

  In fact, it was almost time for Mrs. O’Malley to pick up Egg, Howard, and Lisa. Mark was still annoyed, but Scott had started to feel bad. He didn’t like fighting with people, especially his friends. Deep down, he wondered if maybe Egg, Barry, and Howard might be right. Maybe it wasn’t fair for him and Mark to assume one of them would be the astronaut.

  A
nd there was something else, too. All the Mercury astronauts had been superstar pilots before they ever went to work for NASA. For example, John Glenn, the first American to orbit Earth, had flown more than 150 combat missions in two wars, served as a military test pilot, and won five medals.

  Meanwhile, Scott and Mark had never even been passengers in a plane. Even if a computer did do most of the work, what made them think they’d be able to fly a spacecraft?

  As the group walked outside to meet Mrs. O’Malley, Scott had an idea that he voiced before it was totally thought through. “What if we have a contest?”

  “A contest? What are you talking about?” Mark asked.

  “To determine who gets to”—he looked around to make sure no grown-up was listening—“go up in space.”

  Egg looked interested. “What do we have to do in our contest?” she asked.

  Scott didn’t answer right away, and Barry stepped in. “My brother says the closest feeling to being a pilot is the feeling you get on amusement park rides. So maybe we should have our contest at Great Adventure.”

  Great Adventure was a new amusement park in Jackson, New Jersey, not far from the twins’ home in West Orange. It was supposed to be almost as big and exciting as Disney World in Florida, and Scott and Mark had been begging their parents to take them.

  Mark smiled for the first time in a while. “Now you’re talkin’!”

  Egg said, “Lisa can come too, right?”

  Mark and Scott looked at one another. This was getting to be a lot of people. On the other hand, Lisa knew how to weld. They had a feeling this might come in handy. And the space program had a lot of people working for it too.

  Lisa opened her mouth to say that it was okay, she didn’t have to go, but Mark cut her off. “Why not?”

  Scott said, “Great Adventure sounds a lot better than cleaning and inventorying. We can tell Grandpa it’s educational.”

  “It absolutely is,” said Mark. “How can he say no?”

  CHAPTER 21

  * * *

  “Tell me again how this is part of your spaceship project,” Grandpa Joe said. It was early in the morning, two days later. Grandpa had borrowed a station wagon from a neighbor, and they were driving south on I-95. Barry’s brother, Tommy, had agreed to meet them at Great Adventure to spend the day, the first day they all had free. After that, he’d drive Barry and the twins back home to West Orange.

  “Pilots and astronauts train in flight simulators,” Scott said. “And in jets and airplanes, too, of course.”

  “Which is not exactly practical for us,” Mark added.

  “According to Tommy, amusement park rides are the next best thing,” Scott said.

  A few minutes later, they turned into a parking lot as big as a town, and Grandpa steered the car into a long line being directed by smiling teenagers wearing blue baseball caps. It was only ten o’clock, not too hot yet. Grandpa had insisted that everybody get up early so they could arrive at the park when it opened. He was determined that everyone get the most out of their five-dollar entry passes.

  Walking across the asphalt, the kids and Grandpa saw Tommy standing by the ticket booths, and an instant later he waved. The twins both noticed that Tommy looked better than he had last time they saw him at Barry’s house. His hair was still long, but it was clean and tied back. His beard had been trimmed. His jeans and T-shirt were clean. But the biggest improvement was the smile on his face.

  Well, of course he was happy. They were going to the best amusement park in the state!

  “Great to see you, pipsqueak.” Tommy threw an arm around his brother’s shoulders. “I know Scott and Mark, but who else—?”

  “I’m Joe McAvoy.” Grandpa held out his hand, and the two shook. Barry introduced Lisa, Egg, and Howard.

  “Egg?” Tommy looked at her.

  “You can call me Jenny if you want,” she said.

  Just inside the gates, Grandpa peeled off. “I’m going to get myself a regular coffee and something greasy for breakfast. You kids go on and do your thing,” he said. “We can meet back here under the trees for lunch.”

  From the Ferris wheel to the carousel to the cotton candy carts, everything about Great Adventure was shiny, new, and colorful. Under a blue summer sky, even the blades of grass and leaves on the trees looked painted and polished.

  “What do we do first?” Egg asked.

  “One of the roller coasters—before they get crowded,” said Barry.

  Tommy shook his head no. “Actually, I have a plan. And according to the plan, we do the Big Fury coaster this afternoon.” When Barry frowned, Tommy added, “Part of being either a pilot or an astronaut is being patient. Let’s head for the bumper cars. First one to get there gets ten points. A-a-a-and—go!”

  The kids pulled out their maps, and after a moment Mark took off, followed by Barry and then everyone else. When Mark made a wrong turn at the duck pond, Scott passed him and arrived at the bumper cars first. “Ten points for me!” he crowed.

  “Points.” Barry shook his head. “My brother seems to be real serious about this.”

  “That’s a good thing,” Scott said.

  “Yeah, you think so because you’re winning,” Egg said.

  “It’s early yet,” Mark said. “I am planning to stage an amazing comeback.”

  “Me too,” said Lisa, and the shy, quiet way she said it made everyone laugh.

  “Here’s the deal,” Tommy explained. “Instead of trying to hit each other with the cars, the goal is to avoid hitting each other. Obviously, when you’re a pilot or an astronaut, collisions are a very bad idea.”

  Neither Scott nor Mark thought this sounded like fun till Tommy told them one more thing: He was going to drive a bumper car, too, and he wasn’t going to follow his own rule.

  Inside the ride, Mark chose a red car and Scott blue. They were barely strapped in when a buzz of electricity signaled that the wands were charged—and they were off! Mark imagined Tommy’s black car was a spacecraft and Tommy a space alien out to destroy all that was good in the solar system. Maneuvering to avoid him, he slammed into Lisa’s car—pow!—then called out “Sorry!” and swerved to avoid Howard, whose eyes were narrowed in concentration as he aimed for the ride’s outer edge.

  In an instant, Mark saw Howard’s strategy. Driving on the inside, you could be hit from four directions. On the outside, you could be hit only from three. It was smart, but wimpy and annoying, Mark decided, and he jerked the wheel to cut Howard off, knowing Howard would do his best to avoid hitting him.

  This worked, but Tommy called: “You lost a point, Mark Kelly!”

  “Wait—why?”

  “Rudeness!”

  Soon the ride was over. The idea might have been to avoid collisions, but Mark and Scott both felt plenty bumped around as they climbed out of their cars.

  “Okay, here are the point totals,” Tommy announced. “Everyone but Lisa was hit at least once, and Mark was hit twice, plus he lost that point for rudeness. Scott is winning with eight points, and Lisa is next with zero. Everyone else has negative numbers, Howard and Egg with minus one, Barry with minus two, and finally Mark with minus three.”

  “I am dominating!” said Scott.

  Mark wanted to tell his brother to shut up, but resisted. Instead, he pointed out to Lisa that she was way ahead of him with her point total of zero.

  Lisa looked embarrassed. “Sorry.”

  “Don’t be,” Mark said. “You’re fast and you’ve got good eyes. You earned that zero fair and square.”

  “Okay, people, listen up!” Tommy said. “Our next stop is the shooting gallery. You need good vision to be a good shot or an astronaut. Also, shooting requires steady hands, which means keeping calm under pressure. Space is a hazardous environment where you have to keep calm too.”

  Tommy had barely finished talking when the maps came out and the race began. This time Mark took more care and arrived first, followed by Egg, Barry, Scott, and Lisa. Once again, Howard and Tommy br
ought up the rear.

  “Ten points for me!” Mark said.

  “It would make more sense,” Egg said, “if the second- and third-place people got points, too. Otherwise there’s no reason to run fast once you see you can’t win.”

  Tommy nodded. “Okay. In that case, Egg has five points and Barry gets two.”

  “Whoo-hoo!” Barry cried. “I’m back to zero!”

  “But that’s not fair!” Mark was fuming. “You’re changing the rules in the middle.”

  Tommy shrugged. “A good leader listens to good suggestions.”

  The shooting galleries were Wild West–themed, with the shooters assuming the identities of silver-starred sheriffs defending townsfolk against black-hatted villains, not to mention jackrabbits, bison, flying geese, and mountain lions.

  In spite of her mild-mannered personality, Lisa’s steady hands and good eyes made her an excellent shot. To everyone’s surprise—including her own—she won this segment of the competition, with Barry and Scott taking second and third places. When the smoke had cleared and the dust had settled, Lisa and Scott were in the lead with ten each, then Mark with seven, Barry with five, Egg with four, and Howard with minus one.

  “Where to next?” Mark was determined to make up points and figured speed was his best asset.

  “Drinking fountain. It’s hot out here,” Tommy said.

  “Can’t we get sodas? Grandpa gave me money,” Scott said.

  Tommy shook his head. “Bad for your teeth.”

  “Do astronauts need good teeth?” Barry asked.

  Tommy nodded. “Astronauts and pilots both.”

  Scott spotted a drinking fountain, sprinted to it, took his turn, and asked, “Do I get points?”

  “Not this time,” Tommy said.

  “But Egg got a point when she asked—”

  Tommy gave him a look, and Scott closed his mouth. He didn’t want to lose a point for arguing.