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Turn Left At The Moon

In the previous chapter, "Antimatter", I summarized what we know about the science and technology of antimatter. Most of that material was condensed from a non-fiction book, Mirror Matter: Pioneering Antimatter Physics, which I coauthored with science writer Joel Davis. Instead of making the book completely non-fiction, however, we included a running science fiction story, with a portion of the story appearing as a lead-in to each technical section. Each portion of the story had to cover, in a brief fictional manner, what would be discussed in more detail in the following technical portion. Even with this limitation, I found it possible to put together a short narrative that had a reasonably coherent story line, while still covering all the important aspects of the potential impact of antimatter on future science, technology, medicine, and commerce.

 

The story, as written, does gloss over the radiation hazards of antimatter. Antimatter annihilation does not produce neutrons, as does both nuclear fission and nuclear fusion. As a result, antimatter fuel does not generate secondary radioactivity in the machines that use it, or produce lots of radioactive waste that needs to be disposed of. Nevertheless, it does generate copious amounts of hard gamma rays during the annihilation process, which are only exponentially absorbed by a radiation shield. As a result, some small amount of radiation is always going to leak through even the best shielding. In these days of zero risk environmental regulations, I am afraid that it is unlikely that antimatter will be used for any purposes other than scientific research and medical imaging and treatment, even if we could find a way to get the cost way down below ten million dollars a milligram, which is what would be needed to make some of the applications discussed in the story economically feasible. I was working on the technical background to my novel Martian Rainbow at the time this was written, so you will find a lot of Mars detail in this short story, as well as a number of antimatter powered vehicles in the novel.

 

This version of "Turn Left at the Moon" is the draft that I turned over to my co-author. The version to be found in Mirror Matter is a shorter, jointly authored version. 

 

 

Johnny took yet another look at the blinking mauve polka dot clock with the bright green numbers on the upper part of his screen. The clock said 1740 Friday 25 Sept 2035. He still had another twenty minutes to go on the homework tutor before he could quit for the day.

"The berker thing must be broken," muttered Johnny as he changed the colors on the clock to red stripes with electric blue numbers. The tutor was getting annoyed with his slow response to the last question and had started adding beeps to augment the flashing question mark.

"If 6x+3=27, what is x?"

Johnny mumbled briefly to himself, typed 4, and stuck his tongue out at the screen as it replied with a blinking red "EXCELLENT!". He sighed and started paying attention to the tutor so he would be through his homework before Mom and Dad got home from work. But it was hard to concentrate knowing that Gramma Ginny was probably dying.

It wasn't long before the afternoon lesson was over and the colorful clock chimed the hour as Johnny heard the high-pitched whistle on Mom's Supertrain far off down the valley. Johnny turned off the tutor before it could turn itself off and ran to the picture window that looked down from their home in Les Houches in the French Alps to the deep valley below. Johnny could now see Dad's wheeltrain from Switzerland way off to the right, it was late tonight and Mom would beat Dad to the station for the second time this week.

The Supertrain from Italy slowed from its two-hundred kilometer per hour speed by pumping its kinetic energy back through the linear motor built into its superconducting levitracks and came to a halt. The trees prevented Johnny from seeing much, even through Dad's binoculars, but soon he saw a tiny figure walking to their Nissan electric, parked at one end of the parking lot where his parents knew it could be seen from Johnny's window. The figure waved upward once, then turned and waited for the wheeltrain from Geneva to arrive.

Mom had first met Dad right there in that very station in a large crowd of holiday skiers. She, a materials engineer from the USA and he a physicist from the nearby CERN nuclear research center in Switzerland. By the end of the two weeks they had spent skiing together, they decided to spend the rest of their lives in the Alps. Mom easily found a job with the European Space Agency at the rocket fabrication and test facility in nearby Turin in Italy, and they had lived in Les Houches ever since Johnny had been born—fifteen years ago.

Dad's train finally arrived. Shortly thereafter the family's high powered superconducting electric car started its zooming ascent up the mountain. The Nissan disappeared into the foliage and Johnny had time to worry about Gramma Ginny again. She was feeling real sick and he might never see her again. The thought made him feel sad. He cheered up as he caught a glimpse of the car coming around one of the hairpin turns on the road up to their home. Soon Mom and Dad were in the house.

Later, they were all sitting around the dining room table, having dinner.

"Today was a big day at CERN," said Dad. "We had over two hundred scientists, including a dozen Nobel Prize winners, come in for a special triple anniversary meeting. It's been fifty years since Carlo Rubbia and Simon van der Meer were awarded the Nobel Prize for using antiprotons colliding with protons to discover the W and Z particles. They held the ceremony in the center of the old Low Energy Antiproton Ring, which has just been declared a Historical Monument."

"That will keep the accelerator engineers from cannibalizing it for the parts," said Mom.

"There were two other anniversaries celebrated at the same time," continued Dad. "The eightieth anniversary of the discovery of the antiproton at Berkeley in 1955, and the one-hundred and second anniversary of the discovery of the first antiparticle, the positron, back in 1933 at Caltech."

"Those kind of meetings are fun, but time consuming," said Mom. "What about your research on the anticarbon fusion cycle?"

"The antimatter engineers at the heavy ion collider factories have been finding us enough antihelium nuclei in the output from the colliders to keep our experiment supplied, but we still haven't been able to replicate the Sun's carbon cycle by fusing three antihelium nuclei into anticarbon."

"Wasn't that the whole point?" asked Mom. "If the cycle doesn't work with antimatter the same as it does with matter, then maybe that explains why we can't observe antimatter anywhere in the universe."

"That may be the reason," said Dad, "or it could be that we are just not doing the experiment right. The fusion machine that we are using does a fine job of fusing normal matter helium into carbon, but it could be that the few residual molecules of air that are unavoidably left in the vacuum chamber are helping the reaction somehow. Then, when we try the same experiment with antihelium, the few residual molecules are of no help to the antimatter version of the reaction, since they are normal matter instead of antimatter. We'll have to try lots of variations before we can say anything definite. Six months to a year is my guess. In fact, we'll be shut down for the next three months while the engineers rebuild the fusion machine with an antiproton beam 'vacuum scrubber' to annihilate those residual air molecules and get a better vacuum." Dad took a sip of wine. "How did things go at the ESA test facility?"

"I got almost nothing done," said Mom. "I kept worrying about Mother. I had my technicians run a few of the new high temperature plasma rocket nozzles through the antiproton flaw detection facility, but I couldn't get myself to call up the data to analyze the results. Instead, I spent the day rearranging my computer files."

"I'm sure Mother Ginger is going to be all right," said Dad. "Staying under pressure twenty-four hours a day for weeks at a time is bound to do things to your ear."

"Mother has been an underwater environmentalist for nearly thirty years. This is the first time ear problems have made her so dizzy she can't even swim, much less walk. I think it's something more serious."

Johnny remained quiet. He liked Gramma Ginny a lot. One time he had visited her and Granpa John at their underwater house in the little village, 'Atlantis Too,' on the ocean floor off California. They flew out in a helicopter to the small landing pad above the underwater community. The landing pad was just a minor speck on the otherwise clear ocean horizon view from Santa Barbara. The offshore oil drilling rigs that used to clutter the horizon were now all underwater. They went down to Atlantis Too in a slow elevator that changed the pressure as they descended to the large underwater village below. Granpa John had taken him out to see the underwater oil drilling rigs and showed Johnny the new antimatter drill bit he was testing.

"It holds a little container of frozen antimatter that has enough energy to drill though a kilometer of hard rock," Granpa John had said. "It doesn't vaporize a large hole like a 'Star Trek' disintegrator ray, but instead there are six antimatter beams that punch six tiny holes in the rock and fracture it so the rock drill has no problem grinding it up. The combination goes through hard rock like a hot knife through butter." Later, in Gramma Ginny's kitchen, Johnny had heated up a knife on the electric stove and tried it. A hot knife sure made a mess out of a quarter-kilo of butter.

Granpa John had also showed him the compact power plant that generated all the electricity needed to run the oil rigs and energize the underwater homes of the workers. A small antimatter powered submarine was hovering over the plant when Granpa John drove by the plant in his electric submersible. "They are bringing the monthly supply of antimatter to run the power plant," said Granpa John. "Expensive fuel, antimatter, but at least there are no ashes left to haul away."

Gramma Ginny had also taken him on trips through kelp beds and down into deep canyons. She would use the arms of the manipulators on the submersible to snip off pieces of kelp or pick up oysters and put them in a basket. "I'll have to check these for pollution," said Gramma Ginny. "My last batch from this area showed signs of oil pollution, although there are no drilling rigs anywhere near."

They went down into a deep canyon. It made Johnny's stomach feel funny as the submersible flew over the edge of the underwater cliff and zoomed down into the blackness below.

"Aha!" said Gramma Ginny as she stopped their descent and flew the submersible back up the cliff. There in the searchlights of the submersible were black blobs of tarry stuff oozing out of a crack in the side of the cliff and slowly rising upward through the water. "An oil seep," she said. "I'll have to send a crew over to seal it up."

The telephone beeped in the kitchen and woke Johnny from his daydream. He returned to his dinner while Mom went to the telephone. Fortunately, Mom and Dad had been too busy talking to each other to notice that he had let his food get cold. What little Johnny could hear of the telephone conversation was bewildering.

"Mother! How are you?"

"Oh dear! That's terrible news."

"Oh wonderful! That's good news."

"Oh really!?! That's terrific news."

"Yes! We'd love to. I'll call you right back."

As Mom came out of the kitchen, Dad said, "Your mother must be feeling better if she made the telephone call herself."

"She just went in this morning for an antiproton CAT scan on her head," said Mom. "There was nothing wrong with her ear, but they found a small brain tumor that was pressing on her ear and causing her vertigo."

"A brain tumor!" said Dad. "That sounds serious." It sounded terribly serious to Johnny.

"That's what I thought too," said Mom. "But it was so small, that they just turned up the current in the antiproton beam and cauterized it right there. She was able to walk out of the hospital by herself. The first thing Father had her do was give me a call. Mother said that she had had a lot of time to think while she was lying in bed these past weeks. She had made a decision that once she felt better, she was going to take the time to do some things that she had been postponing for far too long. She has decided to take a vacation tour to Mars!"

"Wow!" said Johnny. "I've always wanted to go to Mars."

"Well you can," said Mom. "She has invited us along. Granpa John has to stay and work on a new oil field, so she's taking us along for company."

Four days later Mom, Dad, and Johnny were passing over the North Pole in a Boeing HT-303 Hyperplane flown by Pan World Express. It was an antimatter augmented hypersonic airplane that flew from Paris to California in three hours. As they came into the Palmdale Interplanetary Spaceport, they could see the large dry lake at Edwards Air Force Base to the north.

"That's where the first Space Shuttle landed," said Johnny, who had been reading through his history files in preparation for the trip.

"See that long line in the desert to the left of the dry lake bed?" said Dad. "That's what's left of the first antiproton factory. It used a long superconducting linear accelerator that goes for twenty kilometers across the desert. Thirty years ago they used that machine to make enough antimatter to run the first antimatter powered rocket. We have much better machines now, that are a lot smaller and much more efficient."

Johnny took his gaze from the window, pulled his portable computer out of his shirt pocket, and started reading about the Palmdale Spaceport. There was a rumbling noise as the landing gear dropped down from the sleek underside of the California Express.

Gramma Ginny and Granpa John meet them at the Palmdale Spaceport and they spent the next day resting, packing for the long trip, and getting checked out by the Spaceport medical staff. So far, Mars had been kept free of almost all of the communicable diseases except the common cold, and the Mars authorities wanted to keep it that way. There was some concern over Gramma Ginny's recent tumor operation, and whether she might have a reoccurrence of the problem during the trip. In that unlikely event, she would just repeat the treatment. The lightweight antimatter CAT machine was a standard piece of medical equipment on-board the Mars Longliner since there was plenty of antimatter available from the fuel tanks to operate it.

The time finally came to leave for Mars. Two hours before the flight they all took their space-sickness pills. Fortunately, space medical research had finally found a solution to that problem. They said goodby to Granpa John, boarded the transfer bus, and were taken out across the large field to the long runway that stretched across the desert. At the end of the runway, ready for its flight into space, was a McDonnell-Douglas AS-3 Spaceclimber, the antimatter augmented aerospace plane that was to take them to the O'Neill at L-4. There they would board the Mars Longliner for their trip to Mars.

Johnny looked out the window of the bus as they approached the sleek craft. It had the general shape of a pointed paper airplane, but a fancy one with twin tails. The surface was covered with grey-white insulating material that protected the spaceplane on reentry. The spaceplane was actually smaller than the hypersonic aircraft that they had used to travel from home to the Palmdale Spaceport. As they got closer, Johnny noticed that there were no wheels, and he could see right under the spaceplane to the other side, the plane was floating in the air a half-meter off the ground. The Spaceclimber used superconducting levitation landing gear that consisted of upside-down bowls of superconducting material built into the frame of the spaceplane, behind the heat insulation skin. The runway had built into it the superconducting magnetic field motors that held up the spaceplane by pushing on the superconducting bowls.

The sixty passengers were carefully tucked into their seats according to size and weight. Johnny and Gramma Ginny were put in the front row, and Johnny got one of the windows. The engines were started at low level and the Spaceclimber started its long glide down the runway, the superconducting motors in the runway saving on fuel by catapulting them up to speed and into the air. As the markings on the ground turned into a blur, the engines burst into a roar and Johnny was pressed into the back of his seat as they took off into the sky.

"One kilometer," said the Captain. "Two... Three... Four..." Insulating shields slid over the windows as the acceleration grew stronger. The Spaceclimber shook slightly as it broke through the sound barrier. "Six... Eight... Ten... Rockets on." The sound of the engines changed as they switched from an airbreathing mode to a rocket mode. "Fifteen... Twenty... Twenty-five. Antimatter augmentation on." The muffled roar of the engines increased as milligrams of antimatter were added to double, then triple the thrust from the rockets. The rockets stopped abruptly and they were left in free fall. The window shields slid back and the Captain turned the Spaceclimber upside down so everyone could look out the top ports at the curve of the Earth below. The sky had turned from blue to black.

"We'll be at L-4 in about twelve hours," said the Captain. "In about one hour we'll be passing through geostationary orbit altitude. We'll pass close to the big glasser that supplies energy for the West Coast communities in North and South America. You shouldn't have any trouble seeing it. The solar cell array is thirty kilometers wide by three hundred kilometers long and produces ten million megawatts of power. That's ten thousand gigawatts, or two thousand old-time Earth power plants. It's also ten terawatts—ten times the total world output of power fifty years ago. This is just one of four glassers. The others supply power to the East Coast of the Americas, Europe, and Russia, while a fifth one is under construction over Asia."

The Captain turned the Spaceclimber so they could see the glasser through the top viewports. "If you look closely in the narrow gap at the center of the solar cell array, you can see a round disk a few kilometers in diameter that sends multiple beams of microwaves to the various power receiving stations in the oceans or at isolated locations in the mountains or deserts. Fortunately, the new underground superconducting power line technology has made it possible to locate the receiving sites far from any populated areas.

"If you have very good eyes, you also might be able to spot the antimatter factories in the gap between the two halves of the solar cell array. If the Earth doesn't need the full power output from the glasser, then what's left over is used for making antimatter. Antimatter thus becomes an economical way of storing, in a compact form, the solar energy that would otherwise be lost forever. Some of the antimatter is shipped to Earth, but most of it stays in space where it's used for powering space vehicles."

Johnny watched intently as they glided past the huge sunlit structure. Dad had left his seat and had floated over to hang above Gramma Ginny and look out Johnny's window.

"I can see the microwave disk real easy," said Johnny. "Are those four little dots the antimatter factories?"

"The two that look like doughnuts are the antimatter factories," said Dad. "The smaller spheres are for processing of materials from the moon and asteroids."

The Spaceclimber passed through geostationary orbital altitude and continued its climb through space. Meals were served and Johnny had fun playing with his food in free-fall. The Captain had the ship positioned so that the Moon could be seen by looking forward out of the upper viewing ports, while the Earth could be seen looking backward out the ports. As the Spaceclimber traveled, the Earth stayed in the same place in the viewports and got smaller, while the Moon stayed the same size and rose up in the viewport frame until it was nearly overhead. As they approached Dyson City at L-4, the Captain rotated the ship and fired the engines to bring them to a halt at the docking port of the O'Neill .

Dyson City had the shape of a huge rotating wheel. There was a basic framework of open girders about two hundred meters in diameter rotating about once per minute to produce just enough gravity to give a sense of "up" and "down". Two opposite quarters of the wheel had been filled in with a curved pressure hull that was fifteen meters in diameter. To Johnny, Dyson City looked like a doughnut with two big bites taken out of it. They landed at the center hub of the wheel and took an elevator down to the A sector. As the elevator descended, they all floated to the bottom of the elevator and began standing on their feet once again.

They disembarked on the upper deck of the A section. Four meters above them was a large curved window that looked inward to the hub and beyond to the curved window of the C sector. Johnny looked up and saw people there. They were upside down, standing on their ceiling, and looking downward at them.

A large mirror to one side of the O'Neill reflected the sunlight into the windows and down through the lightshafts to the farms on the decks below. They had a day before they would board the Mars Longliner, so they began to explore Dyson City. Dad headed for the C sector to visit the Russian cosmic ray scientists, Gramma Ginny went to the lower decks of the A sector to visit the hydroponic gardens, and Johnny followed along with Mom as she visited the construction work going on in the B sector. Although all the sectors were open to everyone, the A sector had primarily been built by the Americans and held the various experimental facilities that they were interested in, while the C sector had been constructed by the Russians. The European Space Agency was expanding Dyson City into the B sector. Because Mom was an engineer for ESA, she got to visit a control center where they could look out a window where construction workers in hard suits with powerful propulsion units and strong manipulators were assembling the various components into a new section.

As they entered the control room, they saw the workers bringing up some titanium alloy plates that were to undergo one last inspection before being welded into place to form the bottom pressure hull and "bedrock" of the huge curved structure. A two by three meter plate was floated in front of the scanner and a beam of antiprotons was swept back and forth over the five centimeter thick plate. Inside the control deck, Johnny and his mother watched the image build up on the screen. In ten seconds the scan was done. To Johnny it looked like a dull grey rectangle. Mom's eyes were keener.

"There is something in the lower left corner," said Mom at the same moment that the computer drew a red oval in the lower left corner of the grey rectangle. The operator rotated and expanded the image and used the contrast controls to bring out the flaw. She started to push the "reject" key, for one certainly does not want to use flawed titanium plates in the construction of Dyson City. If it failed, the results could be catastrophic.

"It doesn't look too bad," said Mom. "I don't see any evidence of a void."

"Just a collection of line dislocations," said the operator. "They can probably be annealed out." She shifted her hand and pushed the "rework" button instead. The plate was prominently tagged and moved by the spacesuited outside construction workers to a separate facility. There, a separate team of workers moved their heavy duty antiproton beamer into position and turned it on. Within moments, a nanogram of antimatter heated up that local region deep inside the titanium plate without heating it up anywhere else and the dislocation flaws in the plate were annealed away. The annealed plate would not be used for its original purpose in the main pressure hull. However, it would still find a use in Dyson City. It was retagged and moved into a special storage orbit. Meanwhile, another plate was brought over by a space construction tug and its interior imaged. This plate was fine. The construction workers moved it into position ready for welding. Dyson City continued to expand.

Everyone went to bed early that night as they adjusted their sleep schedules to space time. Life in Dyson City went on continuously since most of the observatories and experimental laboratories were on twenty-four hour shifts, but those not on shift work lived according to Greenwich Mean Time, which made it easy for Johnny and his Mom and Dad, since they only had to shift one hour from French time. The next "morning" they were taken out on a Dyson City shuttlecraft to the Rockwell IT-2 Longliner operated by Mars Tours Unlimited. The Longliner was aptly named, as it was a half-kilometer in length. The main body was a long girder in the shape of a triangular truss structure that connected the three main components. At the front of the Longliner was the control center and the passenger compartment. Near the center of the truss beam were the propellant tanks containing the liquid methane that was going to be heated by the antimatter and expelled to provide thrust. At the rear of the Longliner were the liquid drop radiators, the radiation shield, and the antimatter rocket engine.

Since the antimatter engines were off, the shuttlecraft took them near the rear of the Longliner to let the passengers see the marvel that had opened up the solar system to tourism. The scotty for the Longliner was traveling out to the ship with the passengers, so he gave them a detailed description of his pride and joy.

"The antimatter rocket engine is not much bigger than some of the chemical rocket engines used on the big boosters back in the 1990s," said the scotty. "It's three meters in diameter inside the annihilation chamber, while the bell of the nozzle expands out to ten meters to get the maximum thrust out of the hot exhaust gases. In each second of operation, the engine uses three milligrams of antimatter to heat fourteen hundred grams of propellant. The power level is five-hundred gigawatts, about fifteen times the power level of the early Saturn Five moon rockets."

The shuttlecraft moved on to the other side of a thick metal disk about three meters in diameter. It was fifteen centimeters thick at the center and tapered down to a few centimeters at the rim. Right in back of the metal disk was a large rectangle about as big as a kitchen refrigerator.

"The big metal disk is the radiation shield, while the rectangular box on the other side is the antimatter storage container," continued the scotty. "Antihydrogen pellets weighing about ten micrograms each are extracted from the electrostatic storage container and sent through a vacuum line that runs through the shield. The antimatter pellets are injected into the center of the reaction chamber of the engine where the antihydrogen annihilates with the hydrogen and carbon molecules in the methane. The reaction products are gamma rays and charged particles called pions. Most of the gamma rays are stopped in the walls of the reaction chamber where they are used to preheat the propellant. Some of the gamma rays get out of the engine, so that's why we need the shadow shield to protect the passenger compartment up front. The charged pions are trapped by the strong magnetic field bottle that's generated by the high temperature superconductor loops you see wrapped around the pressure chamber and nozzle. They also help keep the hot propellant from getting too close to the walls and melting it. All the materials used in the making of the engine are especially chosen low mass isotopes that do not produce long-lived radioactive byproducts if they are fissioned by an escaping gamma ray or pion. Within a day after the engine is turned off it's safe to work on."

They next came to three long narrow troughs that stuck out for thirty meters to each side of the narrow truss backbone of the ship. Further along the truss were a thirty-meter-long array of tiny spray nozzles.

"Those are the 'squirters' and 'catchers' for the liquid drop radiators," said the scotty. "When the antimatter engine is on and we need to get rid of waste heat, the liquid drop radiators are turned on. Red hot drops of liquid metal come streaming out of the squirter nozzles and stream outward into space to cool off. The cooled droplets are then caught by the collector, the cool liquid metal is piped down to the engine components to cool them off, then the hot liquid is returned to the squirters again. Although you will never see them in operation from the passenger compartment except through the rear monitor video cameras, they give the Longliner an impressive glowing triangular tail as it journeys through space. Looks just like a flaming arrow."

They next passed the large propellant storage tanks at the center of the Longliner. There were three of them, each a squat cylinder fifteen meters in diameter and three meters thick, stacked along the truss of the Longliner like beads on a stick.

"These are the propellant tanks. They hold the reaction mass that's heated by the antimatter in the reaction chamber of the rocket engine," said the scotty. "Theoretically, you can use anything you want for propellant in an antimatter rocket. It all gets turned into a blazing hot plasma of ions and electrons by the annihilation pions. Both liquid hydrogen and water have been used successfully in antimatter engines, but we prefer methane since it has four hydrogens for each carbon atom, so it's almost as good as pure hydrogen, but it's much more dense than liquid hydrogen, so the size of the tanks are reasonable. These tanks hold eight hundred tons of methane, or four times the 'dry' weight of the Longliner. If we were taking the tour to Saturn's rings instead of to Mars, we would still only load on eight hundred tons of propellant, the only difference is that we would take more antimatter to heat the same amount of propellant hotter. The reason for three tanks is safety. If one of the tanks is penetrated by a meteorite and we lose propellant, we can make do with the contents of the other two tanks, we just use a little more antimatter and heat the propellant hotter, thus getting the same amount of total thrust out of less propellant. The propellant also provides a little more radiation shielding."

The scotty kept up the chatter as the shuttlecraft moved slowly along the length of the Longliner, where they boarded the passenger compartment. Johnny and Gramma Ginny shared an outer stateroom with a heavy porthole, while Mom and Dad had an inner cabin. Everyone spent most of the time on the upper deck with the large viewing windows and the video monitors for the remote cameras that let them look aft, and the long distance cameras that were coupled to powerful telescopes that gave them close-up views of distant objects.

The Captain of the Mars Longliner met them in the lounge on the upper deck and described the details of the trip.

"We'll first take a short hop over to the Moon to pick up more passengers and some supplies for the Mars base. Then, we'll turn left at the Moon and head straight for Mars. In the old days, with limited rocket power, it was necessary to take a long roundabout elliptical orbit from one planet to another. You had to 'lead' the target planet by almost a half-orbit. With the increased rocket power that antimatter gives us, we just aim for the target planet and drive straight to it. Mars is fairly close at this time of year, so we'll only have to travel about one astronomical unit—the distance between the Earth and the Sun.

"To keep you passengers comfortable, we'll travel at constant acceleration for half the journey, go into free fall for a few minutes while I flip the liner 180 degrees, then decelerate until we are in Martian orbit. On this journey, we'll be traveling at one-sixth Earth gravity, which is about one lunar gravity, or one-half martian gravity. The total travel time will be seven days. I hope you enjoy your journey."

They had the obligatory "lifeboat" drill, but instead of putting on lifejackets and reporting to their lifeboat stations, they each went back to their stateroom, packed a little emergency bag with necessities, then waited. After about five minutes, the individual room viewers were turned on by an emergency override signal, and the Captain's face appeared.

"This is a test. Solar Storm Alert! Everyone bring your emergency bag and report to the Solar Storm Shelter. Repeat. This is a test of the Solar Storm Alert system. Everyone report to the Solar Storm Shelter."

Johnny and Gramma Ginny took their emergency bags, and following everyone else, they headed for the center of the ship where they were ushered through a revolving airlock by the stewards into a small cylindrical room packed ten high with nested banks of chairs. Once Johnny was in his chair, he could see nothing but Gramma Ginny to his left, a strange man to his right, and the captain on the tiny viewscreen in front of him. The viewscreen was nestled under the seat of someone else stacked just above him. The Captain started to speak.

"That was excellent time—twelve minutes. We'll have a good deal more warning than that for a solar storm, so when you hear the Solar Storm Alert, go to your cabins, get your emergency bags and report to the storm shelter. The shielding in this room is sufficient to protect you from the radiation of even the worst solar storm. You will notice that this room has revolving airlocks at the four entrances. This is also our shelter in the extremely unlikely event that we start to lose cabin pressure. When the Loss of Pressure announcement is made, do not go to your staterooms for the emergency bag, but report immediately to the shelter. A steward with an airmask will be there to direct you through the airlock. Above all, do not panic, even a large hole will require more than ten minutes to lower the ship's air pressure by half. Now I will turn you over to the Head Steward."

The face of the Head Steward appeared on the screen. "A solar storm can last up to a week," she said. "Today we are going to pretend we have a four day storm. During a storm, no one is allowed to go to their cabins for anything. During a bad storm, one minute outside the shelter will give you a radiation dose that will make you sick. Five minutes is enough to kill you. When you enter the shelter you must bring everything you need in your emergency bag or do without. As you notice, there is nothing to do in this room but sit. There is a large reading library available through your individual consoles, provided you remembered to bring your reading glasses."

Johnny heard Gramma Ginny groan as she searched through her emergency bag for the nonexistent glasses.

"There are four toilets and four showers in the cylindrical bulkhead at center of the room," continued the Head Steward. "We have plenty of soap, water, and even toothpaste, but did you remember your favorite razor and toothbrush?" Johnny heard mutterings from around him.

"It's now the end of day one, and time for a refreshing shower and a change of underwear," said the Head Steward. More groans.

"It's the start of day two, we'll be serving a cold but nourishing breakfast, and it's time to take the morning medicine your doctor has recommended." Johnny heard a word he wasn't supposed to hear.

"I think the lesson is clear," said the Head Steward, with an amused smile. "When you repack your emergency bags back to your staterooms, please make sure that they contain everything you could possibly need if you had to spend the rest of the trip in the shelter. Good day."

It wasn't long before the Longliner was in a high orbit above the Moon. The Captain had left them in a gravity gradient stabilized mode that kept the viewing ports at the front of the ship constantly facing the lunar surface. The ship was so long that the slight amount of gravity gradient was enough to drift them forward so that they were touching the windows.

Dad was especially interested in the stop at the Moon since his CERN European Nuclear Research Organization was building its next particle accelerator ring on the moon. The sizes of the machines needed to win the next Nobel Prize were now so large that they could no longer be fitted into the continent of Europe. This ring was designed to circle entirely around the Moon, hopping from mountain top to mountain top where possible, and from tower to tower when it had to pass over the lunar plains. The new machine was called the LUPEC, for LUnar Positron-Electron Collider. A beam of electrons was going to circle around the Moon in one direction while a beam of antielectrons or positrons was going to circle around the Moon in the opposite direction. At six different mountain tops spaced around the Moon, the two high energy streams were designed to pass through each other to produce particle-antiparticle collisions approaching one thousand tera-electron-volts of energy or one peta-electron-volt. The LUPEC was actually going to be cheaper to build than the previous, much smaller, machines built on Earth. There was no need to dig an underground tunnel to provide a shield for the stray synchrotron radiation from the high speed electrons and positrons, or to install a vacuum pipe to keep out the air.

At one point, the circular orbit of their spacecraft nearly matched the track of the ring on the lunar surface below, and Dad pointed out the mountain-top sites and the towers under construction as they passed over them. Over on the lunar backside the LUPEC passed near a large installation, mostly underground.

"That's the first large antimatter factory that was built off the Earth," said Dad. "The Russians constructed it here on the lunar backside in 2010, powering it with large nuclear reactors instead of solar cells. It was designed to produce about ten kilograms of antimatter a year. It's still in use, but we have much more powerful and efficient antimatter factories now at the glassers around Earth."

Johnny watched the lunar scenery roll by until he fell asleep floating in free fall. Dad strapped him in a chair in the lounge and let him sleep. He was finally awakened by the klaxon announcing the starting of the engines for their journey to Mars. The noise of the horn woke Johnny up.

"Are we there yet?"

The weeklong journey to Mars was uneventful, with no meteor strikes, no solar storms, and no space pirates. On the second day they passed close enough to an incoming comet that they could observe it with one of their telescope-equipped cameras. The ship's scotty was controlling the camera and commenting.

"It hasn't developed much of a tail yet," the scotty said, "and probably won't, since it's an old comet and doesn't get too close to the sun. Those comets are where we get the methane and other hydrocarbons that we use for propellant in our antimatter ships. Underneath the dark carbon-dust surface is a dirty snowball of frozen methane, water, carbon dioxide, and ammonia. We save the nitrogen in the ammonia for fertilizer, and convert the rest into hydrocarbons and water."

The turnaround came early on the fourth day. The Captain had them go to their staterooms and strap in for the maneuver. Mom had given Johnny a space-sickness pill at breakfast, but he had fooled around with it, rolling it across the table in the low gravity, and had lost it. When turnaround came, Johnny's breakfast turned around too and came up all over the stateroom. Fortunately Gramma Ginny caught most of it in midair with a towel before the ship acceleration returned and plastered it to the floor and bedding.

Later on in the fourth day the Captain made an unexpected announcement. "If you come to the main viewing lounge, you may be able to see one of the fastest objects in the solar system. There is an Interplanetary Express overnight delivery rocket from Earth to Mars catching up to us. It has just made turnover and is pointing its nozzle in our general direction. Since we have also made turnover so the front of our ship is pointing at Earth, you should be able to see the express rocket easily from the front view windows."

Everyone crowded into the lounge and looked out at the bright star moving visibly toward them. The ship's scotty had the telecamera on it too, but you could see little on the screen but the glare of the antimatter powered exhaust.

"The engineers on Mars had an electrical fire in the control room for the main antimatter power plant at Tharsis Base," said the scotty. "The express rocket is bringing in a new control computer. Those little rockets are engineering marvels that put my engines to shame. They accelerate at ten gravities and reach more than one percent of the speed of light at the half-way point to Mars. Then they flip over and decelerate at ten gravities—getting to Mars in just under twenty-two hours. A true interplanetary overnight express. It's a wonder to me that the engines can survive under the heat, stress, radiation, and acceleration they are under."

"That's one of my rocket engines," said Mom quietly but proudly to the scotty. "Our plant builds the engines for Interplanetary Express, and I safety scan all the engines before they go out."

On the seventh day Johnny woke up early.

"Are we there yet?"

"Almost," said Gramma Ginny. "I can see Mars down at the bottom of our viewport. Hurry and get dressed and we can go out and watch them dock at Phobos. Better take another space-sickness pill." She handed him a pill and a sipper of water from their washstand, and waited until she saw him swallow the pill.

Right after breakfast the klaxon sounded and the main antimatter engines were turned off. The Longliner had matched orbits with Phobos and the landing crew at Hall Station were bringing out a flexible passageway to connect the ship to the tiny moon. They had a half-day on Phobos before they went down to the surface of Mars, and a tour guide took them on a tour to some nearby sites around Hall Station.

"As you saw when you docked, Phobos is not round and varies from twenty to twenty-seven kilometers in diameter. The reason that it's not round is that the gravity field is too weak to pull the planetoid into a spherical shape. In fact, the gravity is so low, you can almost jump off this planetoid. So you will all be roped together in groups of twenty with two experienced guides at each end."

They all soon learned the slow bounding kangaroo hop that enabled them to move along the dusty surface. Johnny was near the middle of his group and often found himself floating along many meters from the surface. They visited the automated comet and asteroid observatory that searched for new comets and asteroids that were in orbits that might take them into the inner reaches of the solar system where they could be harvested of their metals and volatiles. The longest journey was to the center of Stickney crater, where a team of geologists were using an antimatter drill to map the trapped ice and other volatiles under the surface. The comet head which had made the ten kilometer wide crater in the twenty kilometer wide moon had brought with it a lot of water ice.

They spent the "night" in their staterooms aboard the Longliner and early the next day boarded the Mars aerospace plane that was to take them to the surface of the planet. It was a McDonnell-Douglas AS-3M Marsclimber, a Mars version of the Spaceclimber that had taken them off the Earth to L-4. They drifted away from Hall Station using chemical rockets, and as soon as they were a safe distance away from the planetoid, the antimatter augmented rocket engines burst forth a flaming plasma jet and the Marsclimber fell out of orbit and dropped toward the surface below. Johnny again had a window seat, but just as things were getting interesting, the insulation shields slid over the viewing ports and they had to watch the rest of their fiery descent through the thin Martian atmosphere on the video.

Since this was a tour group, the Captain of the Marsclimber halted their descent when they reached low martian orbit. He opened the viewing ports, rolled the Marsclimber until the upper view windows were facing the surface, and gave them a guided tour of the planet through the next few orbits. It was winter in the southern half of Mars and the South Pole icecap was fully developed.

The aerospace plane then reignited its antimatter augmented rocket engines, dropped out of low orbit and spiraled downward once again. The extra large air intakes began to suck in the tenuous Martian atmosphere and the engines switched to airbreathing mode. But since the Martian air was mostly carbon dioxide and wouldn't burn, the antimatter had to supply all the energy to heat the air for thrust.

The aerospace plane sailed in over Solis Planum and landed at the long runway at Tharsis Base in the shadow of Pavonis Mons. Although Mars had an atmosphere, it was only one percent that of Earth. As far as the human body was concerned, it was a vacuum. A crawler came out to the plane, mated with their airlock, and took the tour group to the Penelope Hotel in the sprawling town of Boston outside Tharsis Base.

"It sure feels good to get some weight back on after all those days at low gravity," said Dad. "Thirty-eight percent Earth gravity is just right, you feel light, but your feet stay on the ground. Johnny didn't really like it. He much preferred bounding around in low gravity like he had seven league boots on.

For the next two weeks the tour guides kept them busy visiting one site after another. An antimatter powered Mars Hopper rocket zoomed them in one large leap to the top of Pavonis Mons, then over to Olympus Mons, each twenty-seven kilometers high, then back to Tharsis Base. An antimatter powered crawler took them on an overnight, overland journey to the chaotic terrain that formed the western end of the Valles Marineris.

"It sure looks like underground water subsidence to me," said Gramma Ginny. "But where has all the water gone?"

They next boarded a Mars Airglider. Although the atmosphere is very thin on Mars, an airplane can fly if it has a large enough wingspan. Fortunately, the fuel it carried weighed almost nothing at all, since the energy source for the airplane was the same as most of the vehicles on Mars—antimatter. The Mars Airglider took them slowly down the Valles Marineris, often flying a kilometer or so below the cliff edges of the three kilometer deep fissure in the skin of Mars. The deep canyon went on for thousands of miles and they stopped at for the night at "Chasma Corners", where the main chasm branched out into two smaller valleys.

The next day they took the northern route along Capri Chasma for a thousand kilometers, then headed north across Chryse Planitia to visit the Mutch Memorial. Viking Lander 1 was still there, surrounded by a low fence that encircled the site at ten meters distance. The ancient lander was covered with red dust and beginning to look like the boulders that it squatted among.

The next hop was a long one, as they flew directly north and finally landed just after midnight in full sunlight at Camp Boring at the entrance to Chasma Boreale. The winds off the pole were too tricky to risk the Mars Airglider, so after some rest, they traveled in a heated antimatter snowmobile that took them up Chasma Boreale to see the layered cliffs of ice and dust that rose up hundreds of meters on each side. Johnny wished that he could go out and make a Martian snowball, but he knew the mixture of water ice and frozen carbon dioxide would be too cold to touch, much less pack into a snowball.

Their last stop was the lowest spot on Mars, the bottom of the Hellas Basin. This region was four kilometers below "sea level" on Mars and the air was much thicker. This was also the site for the other major spaceport on Mars. The two weeks on Mars went all too fast for Johnny.

"Do we have to go so soon?" he asked.

"Perhaps you'll come here some day again by yourself," said Dad. "Haven't you always said that you wanted to be the pilot of an aerospace plane? Perhaps your first command will be a Marsclimber instead of an Earth Spaceclimber. Have to get good grades in school though ..." he added.

Johnny made a disgusted face. Dad was always jerping him about his schoolwork. He could do better though, he had to admit.

The vertical ascent on the Marsclimber went much faster than their leisurely descent had taken, and they were back at Phobos in a few hours. During their two weeks on the surface of Mars, the Longliner had gone back to Earth and was now back with a new load of passengers. This time Johnny and Gramma Ginny took the inner cabin and let Mom and Dad have the viewport. They were two days out from Mars when the big moment of the year, and perhaps the decade, rolled around. It was time for the launch of the first interstellar probe to Alpha Centauri. Mom knew all about it, since it was one of her rocket engines that was going to send the robot probe on its way.

"It was one of those coincidences that occurs only rarely on a production line, even a precision production line such as we have for rocket engine assembly," Mom was telling the Captain at dinner. "I had heard rumors about Number 33 even before it came to me for inspection. Every part for every pump, actuator, and subassembly had exactly the right tolerance, no more, no less. Every subassembly performed at the top of its range. The assemblers began to talk about Number 33 and take special care when they were working on some part of it. By the time it got to me for final flaw inspection I could find no flaws anywhere. Then, in the final test stand checks, Number 33 set a record for efficiency and thrust that has not been exceeded to date. We knew we had a special engine and we decided not to deliver it to International Express, but keep it for a special time. That time is now."

"Do you mean the engine on that interstellar rocket is the same type that's used for the overnight express rockets?" asked the Captain in amazement.

"The interstellar rocket is going to accelerate at ten gravities, just like the overnight express rocket. Since they are antimatter rockets, the mass ratio will be the same for the interstellar rocket as for the overnight express, four tons of propellant for a one ton vehicle. The major difference is that instead of having to go at ten gravities for one day, the interstellar rocket is going to have to keep up the ten gravity acceleration for eighteen days," said Mom. "Eighteen days at ten gravities multiplies out to half the speed of light. We think Number 33 can hang together for eighteen days."

"Amazing!" said the Captain.

"There are a few differences, of course," said Mom. "The fuel tanks will hold liquid hydrogen instead of liquid methane to improve the exhaust velocity, and instead of carrying three hundred grams of antimatter, the interstellar rocket will be starting out with three hundred kilograms. The combustion chamber will be running at a higher temperature since we'll be using a higher ratio of antimatter to propellant, but the superconducting coils around Number 33 have already demonstrated a stronger magnetic bottle than any other rocket, and the cooling systems were also the best we have ever seen. I'm sure Number 33 can do it."

The ship's scotty had found the coordinates for the launch point of the interstellar rocket and had the longest focus telescope pointed in that direction. The rocket was at a safe distance from L-5, not far from Feynman City, where most of the advanced space engineering took place. The scotty had half the video monitors showing the countdown as broadcast by an Earth television station, while the other monitors showed the view through the ship's long focus telescope, which was watching the dark region near the tiny speck of light that was Feynman City. The countdown was down to five minutes. The video link from Earth was showing the long sleek lines of the interstellar vehicle. The words "Centauri Express" were written on the body, while the engine proudly showed the number "33".

"Of course, the launch has already occurred," said the scotty. "Since it takes the television signals more than six minutes to get to us here out near Mars."

After about five minutes of waiting, there was a gasp from everyone as the monitors showing the view through the ship's telescope lit up in a brilliant glow and a bright streak started moving visibly across the screen. Two seconds later on the screens carrying the television relay from Earth, the proud 33 disappeared in a puff of ash, the liquid droplet radiators turned into bright red triangular feathers, and the Earth broadcaster announced in a loud voice, "We have ignition!".

Some of the people near Johnny seemed bothered by the delay, but Johnny knew all about the one second time delay from lunar orbit to the Earth and back out again.

Johnny looked proudly over at his Mom and found her face full of concern, her hands tightly clenched. She seemed to be muttering something.

"Go! Go! Go!" she was whispering. After a long minute she seemed to relax. She leaned over and whispered to Dad. "If it was going to blow, it would have done it by now. Number 33 is on its way."

"There it goes!" announced the scotty, as the bright streak faded into a tiny white light.

"There it goes," whispered Mom to herself, "and part of me is going with it."

"There it goes," whispered Dad to himself, "from a white streak in a bubble chamber to a white streak through interstellar space in just a hundred years."

"There it goes," whispered Johnny to himself, "and I'm gonna be Captain of the first ship to follow it."

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