Asteroid Crisis Read online

  “Wouldn’t that help, either way?” JJ asked. “If one of the asteroids broke in two, that would decrease the threat.”

  “Maybe not, Cadet,” Ansari said. “Two five-kilometer-diameter asteroids slamming into Earth would be nearly as bad as the impact of one ten-kilometer-diameter asteroid.”

  “I see your point,” JJ said.

  “It’s important to know whether the asteroids are primarily composed of rock and metal, or ice and frozen gas,” Ansari said.

  “Ice and gas? That sounds more like a comet than an asteroid,” Tony said, a little confused.

  “Asteroids and comets are similar—leftovers from the cloud of gas and dust that collapsed to form our solar system 4.5 billion years ago.”

  “But I thought there were obvious differences between asteroids and comets,” Song-Ye said.

  “The line of distinction can be fuzzy. Most asteroids orbit in the major belt between Mars and Jupiter. They’re generally composed of solid rock, with some pockets of ice. Comets, though, have more elongated orbits—they head farther out into the solar system and then swoop in close to the sun. That’s when they become visible, as the gases evaporate.”

  “That’s what makes a comet’s tail,” King said, “the fresh gases streaming out away from the Sun.”

  “Asteroids or comets, anything that big smashing into Earth is a disaster,” Dr. Kloor said. “Our probes showed that these asteroids are all between three and five kilometers in diameter—large enough to cause serious damage if they impact Earth. On the positive side, they’re small enough that we have the capability to affect their movement.”

  Ansari nodded. “Hence the mission we’re planning. A sufficiently large explosion should deflect them, change their orbits. That still won’t take care of the Kylarn, but we’ll have breathing room in the meantime.”

  The gruff, bearish Russian captain pulled himself the rest of the way into the command module and grinned to see the Star Challengers. JJ brightened. “Captain Bronsky!”

  “By sufficiently large explosions, the Stationmaster means nuclear warheads,”’ he said. “Most nations on Earth dismantled their stockpiles of those old weapons, but some were hidden here and there—and a good thing too. Otherwise we wouldn’t have any way of moving the asteroids.”

  Over the station intercom, a clipped British voice said, “Stationmaster, we are prepared to detach Hab Module 2. This is the third and final module for independent launch on the asteroid missions.”

  “Is that Major Fox?” King asked. JJ remembered the stiff and formal British officer who had helped them at Moonbase Magellan.

  “It’s Colonel Fox,” Song-Ye reminded them, then glanced at Ansari. “Unless he’s been promoted again? Is that why he’s up here?”

  “Colonel Fox was never satisfied with a desk job on Earth. While we were prepping the asteroid mission, he insisted on being transferred up to the ISSC during the next crew rotation. He’ll pilot a module out to one of the three asteroids. I’ll be in charge of the second module.”

  “And I will fly Asteroid Mission 3,” said Bronsky.

  King pulled himself over to Central’s windowport and stared at the interlinked, bus-sized cylinders that comprised the ISSC. A flurry of spacesuited workers surrounded one of the node rooms, preparing to detach Hab Module 2 from the main framework. JJ drifted beside him and spotted two other modules already separated, hanging in space not far from the station. The self-contained cylinders were covered with construction girders; on the bulky framework, a large engine was being connected to the rear of the modules.

  JJ suddenly realized what was happening. “You’re flying station modules out to the asteroids?”

  “It was the best and fastest solution,” Ansari said. “Although I hate to dismantle part of the ISSC, our modules are already built and equipped with life support. We’ve got to make use of what we have, and the modules are already here. We’re still installing the new ion spacedrive propulsion systems, and we have to bring up the nuclear warheads that will move the asteroids.”

  “Look at the size of those modules,” Dr. Kloor said. “It’s an enormous problem to get something so large and heavy out of Earth’s gravity. Do you know what escape velocity is?”

  Dyl answered, with a slight teasing tone, “I’ll bet you’re going to explain it no matter what we say.”

  The physicist immediately began. “On Earth, if you toss a baseball straight up into the air at a velocity of one kilometer per hour, it goes up and comes down. If you throw it hard—at, say, fifteen kilometers an hour—the ball will go higher into the air, but still falls back to the ground. You could even use an artillery gun to shoot the ball upward at over 5000 kph, and it would still come back down.

  “Escape velocity is the speed you have to achieve to throw something completely out of Earth’s gravity. From the Earth’s surface, it’s about 40,000 kph! That’s not an easy speed to hit, even with something as small as a baseball—try lifting a giant space station module! That requires a lot of thrust and rocket fuel, and our time was already short.”

  “After you get to orbit, space travel is much easier. But lifting objects into orbit has always been a barrier to the exploration of space,” Ansari said. “Imagine you’re riding your bicycle along a flat desert road. It’s easy enough, but what if you need to get from the base of a cliff up to the top of a mesa before you can start riding? Once your bike is on top of the flat mesa, you can ride easily. But getting up the cliff? That’s the hard part. But even up here, 300 kilometers above the Earth with the hard part out of the way, it’s still over 11,000 kph faster than the 27,000 kph we’re already traveling to stay in orbit.”

  JJ remembered where she had read about this. “That’s why it’s so important to have a base on the Moon or in orbit for further space exploration.” Moon, sweet Moon, she thought. “The Moon has much lower gravity, which makes the escape velocity from the Moon really low. So if we could use lunar materials to build spacecraft or space stations, the cliff is a lot smaller to climb.”

  “Correct,” Bronsky said. “In fact, the Moon’s surface escape velocity is only about 8,000 kph, and you then have to add the escape velocity from the Earth at the distance of the Moon, which is another 5,000 kph for a total of 13,000 kph—still much easier than escaping from Earth’s surface.” He sighed. “But we won’t have a moonbase again until we defeat the Kylarn.”

  “Commence detachment,” Ansari ordered into the intercom. “And when you’re finished, Colonel Fox, I have some people here who would be interested in seeing you.”

  “Do you indeed? I look forward to it. Fox, out.”

  JJ, King, and their friends watched as the busy space construction workers sealed off the node room and removed the connector bolts. Then they used small propulsion jets to nudge the large cylindrical module in a slow and graceful drift away from the ISSC.

  “So that thing is going to make it all the way out to the asteroids,” Tony said.

  “All three of them are,” JJ replied with a growing smile. “And it looks to me like those modules have enough room inside for a couple of short-term visitors during the mission.”

  ***

  Eight

  After detaching the third ISSC module in preparation for the asteroid missions, Colonel Fox’s EVA crew re-entered the station. Ansari made a stationwide announcement on the intercom system stating—without explanation—that JJ, Dyl, Song-Ye, King, and Tony were “unexpected temporary guests” and asking the rest of the crew to cooperate with them as needed.

  “Remember,” she added, “their mission details are classified, but their assistance has been invaluable in the past.”

  When the EVA team was safely back in the equipment module, JJ and her friends went with Ansari to meet the British officer. JJ had fond memories of when she and King had traveled with Major Fox to the Kylarn base on the far side of the Moon.

  By the time they reached the equipment module, Fox had finished removing his spacesuit and stowing the
components away. The man was compact, with shadows of fatigue under his eyes and more salt than pepper in his hair. His face was serious, his lips pressed into a straight line below his mustache. Fox had been suspicious of the teens when they first arrived at the moonbase, but he had grudgingly come to accept the Star Challengers after working with them.

  Holding onto a support handle on the module wall, Fox regarded them. “Cadets, you haven’t changed a bit. It’s been years since the attack on Magellan. I’ve given up trying to understand your comings and goings, but I’m glad you’re on our side. It’s good to see you. There’s plenty of work afoot, but I suppose you already know that.”

  “We probably won’t stay long,” King said. “But we’ll pitch in on whatever you need us to do.”

  “We’re supposed to help you prep the asteroid mission,” Song-Ye added.

  “I understand that if it hadn’t been for your sharp eyes and curiosity, Cadet King, we’d never have known those asteroids were diverted from their orbits.” Fox’s stern expression softened. “Frankly, I’m glad to be in the thick of things again. It took a bit of convincing, but I managed to persuade the combined militaries that I needed to direct this operation in person. Fortunately, I got Major Rodgers to go dirtside—that’s down on Earth—and run Central in my absence. He’s Lieutenant Colonel Rodgers now.”

  JJ grinned. “Good choice. What have the Kylarn been up to in the meantime?” JJ looked at Ansari. “Have they left Earth alone since we chased them off the station?”

  “As far as we can tell, but it’s hard to say. Now that our new Eye in the Sky satellite is in position at L-5, at least we have a way to observe the far side of the Moon. There is a great deal of activity.”

  “You know the squidbutts are probably watching us right back,” Dyl said.

  “Without a doubt,” Fox agreed.

  Over the station intercom, Pi announced, “The new booster just arrived here in orbit along with a shipment of warheads for the asteroid missions.”

  Ansari answered. “Good. Dispatch four crew in Manned Maneuvering Units to take the cargo to the mission modules.”

  “Aye, Stationmaster. Once we assemble the plasma spacedrive engines, we should be ready to launch all three asteroid missions on schedule.”

  Fox wore a distant expression. “I never thought I’d be so happy to see a shipload of nuclear weapons.”

  “It’s strange to think that every nuclear nation is joining in this effort. Now these terrible weapons just might save the world,” Ansari mused. “Some people think that research should be conducted for purely scientific reasons, but without some incentive, many advances would never have been made.”

  JJ said, “The United States and the Soviet Union invented missiles and hydrogen bombs to threaten each other with nuclear war. The Cold War was over before I was born, but I’ve read about it.”

  “The Cold War was over before any of our grandparents were born, Cadet,” Ansari said.

  JJ blushed. Sometimes she forgot that they were more than a century in the future. “Of course. Anyway, some good came out of that situation,” JJ continued, even though the whole subject must seem like ancient history to the rest of the ISSC crew. “The rivalry between the U.S. and the Soviets also started the space race. Without that, and the contest to put a man on the Moon, I doubt there would even be a space station now.”

  JJ, who made a hobby of learning about space programs around the world, couldn’t help talking about it. “Sure, the two superpowers made the world a pretty tense place, but each side made lots of breakthroughs—launching rockets, satellites, and manned missions to space. All because the United States and the Soviet Union were working so hard to top each other. In 1957 the Russians launched Sputnik—the very first orbiting satellite—and four months later, the U.S. launched Explorer 1. In 1961, the Russian Yuri Gagarin became the first man to orbit the Earth. A few weeks later, ‘Ice Commander’ Alan Shepard was the first American in space, and only a year after that, John Glenn was the first American to orbit the Earth. And so on.”

  “Does it matter which country made the progress?” Ansari asked.

  “It did at the time,” JJ said.

  In fact, the space rivalry had gotten so heated that in 1961 President Kennedy announced the goal of putting an American on the Moon before the end of the decade, which upped the stakes and created a race to the Moon. Over the years, a series of firsts went into the history books: In 1963, the Russian Cosmonaut Valentina Tereshkova became the first woman in space. In 1969, Neil Armstrong and Buzz Aldrin in Apollo 11 were the first men to walk on the Moon. In 1975, after almost twenty years of rivalry, Americans and Soviets worked together on the Apollo-Soyuz mission; when the two spacecraft docked in space, it signaled a new era of cooperation.

  “And even though the Cold War put the world on edge for decades,” King said, “the research and tech spinoffs from those space programs have helped the world since then. Kind of a silver lining to the dark cloud.”

  “I doubt that the manufacturers of our nuclear missiles expected them to be used for anything other than war, but I’m certainly glad we have them available to help us divert those asteroids.” Colonel Fox drifted over to one of the viewing windows and looked out at the spacesuited men and women using their MMUs to jet away from the station and meet the large cargo container drifting along the orbit toward the ISSC.

  Four other crewmembers drifted past the Star Challengers, exiting the equipment module at the end of their shift. The strangers shot curious glances at the five young people. JJ didn’t think she would have time to get to know all of the new crew. The Star Challengers would probably stay aboard the station for a day or two, gathering information so Commander Zota could send them on to the next phase of their mission.

  Unexpectedly, Dr. Kloor and Security Chief Napali opened the hatch from the nearby node room and pulled themselves toward the group. Napali looked tough as nails, as usual, and the physicist did not seem pleased. “I know who you are now!” Kloor said. “I figured out where you’re from, so don’t deny it.”

  Ansari and Fox looked intrigued. JJ’s stomach fell. Napali and Kloor drifted toward them. “I thought about every instance, then I checked the records of your previous visit at Moonbase Magellan. Chief Ansari filed detailed reports, you know. Aside from the impossible fact that you magically appear and disappear without using any sort of spacecraft, it’s also very curious that for people on a classified and highly skilled mission, you cadets don’t seem to know much of anything. You weren’t familiar with the moonbase. You arrived at the ISSC and didn’t know anything about current events. Now you’re back and still don’t know about any of our widely publicized preparations for dealing with the asteroids. In fact, you have no idea what’s happened since you were last here.”

  Napali picked up the conversation; obviously, the two had discussed the questions beforehand. “On the other hand, you seem to know an awful lot about the Kylarn—details we haven’t even discovered yet. You know what they call themselves, and you claimed to know their intentions, long before we had any evidence.”

  “Wait a minute!” Tony protested. “Are you implying that we’re squidbutt spies?”

  “Mira might be, after all,” King said in a low voice. “She proved that.”

  “But we’re the good guys!” Dyl piped up.

  “When you keep arriving out of nowhere, you can’t expect people not to ask questions and press for answers,” Colonel Fox said. “We’ve given you the benefit of the doubt because you were so helpful—but Cadet Mira has made everyone more cautious.”

  “I know,” King said in a low voice.

  “No, I’m not accusing you of spying. I think the answer is stranger than that,” Kloor said, like a prosecuting attorney preparing to pounce. “You young people come from a different time! That’s why you don’t age. You don’t arrive by spaceship—you’re somehow transported through time. You arrived at the moonbase nearly three years ago, just before the Kylarn base
was discovered, then you appeared on the ISSC almost two years ago, and now here you are again. I checked the images from your first visit—you haven’t changed at all since the beginning.”

  JJ’s throat was dry, and she tried to think of a good answer.

  “Uh, you’ve been watching too many movies,” Dyl said.

  Kloor remained adamant. “I’ve been looking at evidence and drawing the most logical conclusions. Do you deny it?”

  Ansari and Fox waited in wide-eyed silence to see how the young people would respond.

  JJ looked at her fellow Star Challengers, wondering how they could still keep their mission secret, as Commander Zota had asked. And in those few seconds of hesitation, Dr. Kloor got all the answer he needed. “I knew it! Are you here to change history? Are you here to erase our timeline?”

  “No! That’s not it,” JJ finally said. “We’re trying to save history! We’re trying to help humanity get prepared.” Even though Zota had insisted on secrecy, they were in a different version of the future now. When King and Song-Ye looked shocked at what she had revealed, JJ said defensively, “We have to trust someone.”

  Tony followed JJ’s lead. “Now do you all understand why we couldn’t tell you anything?”

  Ansari seemed to have trouble accepting what she heard. “So you come from the past to change what happens here? Or do you learn from the future, go back, and try to change things in the past?”

  “We’re trying to help the human race prepare, to give us a head start before the Kylarn arrive,” JJ said. “If we focus on research and discovery, develop technology decades sooner, and keep the space program strong, maybe the Kylarn won’t bother us. We know now that the first alien scouts are going to spy on Earth in our lifetimes.”

  “But if you change all that—our past—what if we’re never born?” Napali asked.