Martian Rainbow

by Robert L. Forward

  "Let us not sit here observing out the window of the crawler," Antonio said, noticing Chris out on the snow with his air analyzer. "We should be outside with our cameras and equipment gathering data."

  ANTONIO read the readouts on his materials composition analyzer. He had just fed it a sample of the dull black ice that was ejected periodically from the rear of one of the hardworking Lineups.

  "Almost pure water ice and elemental carbon," Antonio said. "The buried layers of ice they are eating contain twelve percent carbon dioxide and five percent ammonia frozen in with the water ice. But they are removing the carbon dioxide and ammonia and passing the ice on through after mixing it thoroughly with carbon black so it absorbs sunlight better. What is amazing is that the temperature of the eliminated ice is not significantly greater than the ingested ice."

  "It's hard to get exact figures because of the background atmosphere and all the leaking human pressure suits around," Chris said. "But I'm pretty sure that they are turning the frozen ammonia and carbon dioxide into gases. About one-fourth of the carbon dioxide is left as it is, the other three-fourths is converted into oxygen, methane, and the carbon black they are mixing with the ice. They must have a pretty remarkable digestive system if they can selectively process all the other molecules, while essentially passing the water ice through unchanged."

  "Something's happening over here!" a tech yelled. "One of the Lineups is doing the splits!"

  Chang Lu, Antonio, and Chris ran over to where the Lineup lay sprawled on the ground. Its four front feet were all to the left side of the recumbent body, while the four rear feet were on the right side. The elongated body of the Lineup was twisted about the central section, where a full complement of eyerods jutted out between the seam. The Lineup twisted some more, then two clawed paws, one from each side of the middle, reached out to grab each other and increase the twist. Suddenly there was a giving of the middle section and the long, eight-legged Lineup segment became two short, four-legged Lineup segments.

  "Identical twins," Chris said.

  "Not quite," Antonio said. "The zebra stripe pattern is slightly different. The front one has an outer stripe that is black, while the rear one has an outer stripe that is white."

  "They all have the same basic pattern of stripes in the middle," Chang Lu said, looking around at the other Lineups." But they are all different in the outer stripes."

  "Just like the old product identification stripes they used to use in grocery stores before computers got smart enough to read labels," Chris said.

  "Very strange," Chang Lu said. "Much too orderly for a biological creature."

  "There goes another Lineup into a sprawl," Chris said, pointing. "Pretty soon we'll have eight instead of four."

  "Their replication rate is astounding," Antonio said. "It is only five days and they have replicated three times."

  "The first one probably started out pretty well fed," Chris said. "So it takes them two days to process enough ice and dirt to replicate. That's not surprising, the way they eat. They must pass a ton of ice a sol when there is lots of sunlight. All they need to do is find fifty kilos of good stuff in that ton."

  "With the chemical capabilities of their digestive system, all they need is carbon dioxide, water, and perhaps a few trace elements," Chang Lu said. "There is certainly all they need in the ice and dirt."

  Chris had been punching the number icons on his vidofax. "The way I figure it," he said, "they will exceed the nearly ninety billion population of Earth in just thirty-seven replications—a little over ten weeks from now."

  "They will completely cover the polar cap!" Antonio exclaimed.

  "I think that's the idea," Chris said, putting his vidofax away with a smile.

  "I SAID, 'Proceed with plan,' and the little bugger just snouted right into that gray dirt like it was honey," Maury said, taking a sip of Caldera beer in the Olye Olye Outs Inne bar. He looked down appreciatively at his glass. "They sure don't make good brew on Phobos like Jim does here. Must be the low gravity or something." He looked up at Gus and Jay again. "I stayed around to watch the first few replications, but after a while it got disgusting, so I took the next orbiter down."

  "Disgusting?" Gus said.

  "Well, the biologist types might find it interesting," Maury said. "But when the nose falls off a creature and wiggles into the ground like a worm, I call that disgusting. Especially since it grows a new nose and does it again. Pretty soon every Lineup had a couple of dozen ground-worms helping it root through the loose dirt it had clawed up. Looking for the good stuff, I guess."

  "It would certainly improve its efficiency at processing the soil," Jay said.

  "That's not the most disgusting part, though," Maury continued. "After a groundworm is loaded up with as much as it can carry, it has to transfer that load of nutrients to the main Lineup ..." He paused.

  "Does it hook back onto the nose?" Gus asked.

  "No," Maury said, grimacing. "Wrong end."

  "Of course," Jay said brightly. "The Lineup segments connect together nose-to-tail to make longer segments, and the segments share a common bloodstream, nervous system, and digestive tract through that connection. Thus, they have a built-in place for the groundworms to hook into. Neat!"

  "Neat to you scientist types," Maury said. "Disgusting to me. The groundworms crawling up the rear eyerod fans looked like fat maggots crawling up their skirts, then thin maggots dropping out again. I couldn't stand more than a few minutes of it."

  "I'm sure many of the things we do look just as disgusting to them," Gus said. He turned to Jay. "What is the latest news from Phobos about the progress there?"

  "The Lineups are doing real well," Jay said. "Their replication rate is higher on Phobos since they don't have to heat up ice. They have already started on the mirror-building phase."

  "I still don't see how diamond can be made to reflect sunlight," Maury said. "Isn't it transparent?"

  "Think of it this way," Jay said. "Even though a pane of glass is transparent, when you look through it you see a weak reflection of yourself in the front surface, like it was a poor mirror."

  "Yes," Maury admitted.

  "Well, there are actually two reflections," Jay said. "One off the front side and one off the back side. If you make the pane of glass real thin—a quarter of a wavelength of light thin—then the back reflection comes out in phase with the front reflection and they reinforce each other, making a single sheet of quarter-wavelength-thick glass a moderately good mirror. Then if you put another thin sheet a quarter of a wavelength behind the first one, it will not only reflect the light that gets through, but do it in phase with the first sheet, making the combination a slightly better mirror. The Lineups are going to use eight layers of diamond of slightly different thicknesses alternating with seven layers of vacuum. They expect to get better than three nines reflectance over the whole solar spectrum—much better than any metal mirror."

  "Three nines?" Maury asked.

  "Ninety-nine point nine percent," Jay said. "Less than one tenth of one percent of the sunlight will get through. They expect to do better than five nines in their laser mirrors, since they can be tuned to a single wavelength of light. They'd better; at the power levels they're going to operate at, the diamond would convert to graphite if much laser power got absorbed in the mirrors."

  "When is the first laser launch?" Maury asked.

  "Day after tomorrow," Jay said. "Won't be much to see except the sail moving away. The laser line in the Martian atmosphere the Lineups are using is in the long infrared. The Lineups can see that color, but we can't."

  A FEW days later, half of the humans on Mars were outside in Marsuits watching the large gossamer sail floating motionless in the sunlight above Mars. It was light enough that the sunlight was already pushing it outward toward the asteroid belt, but the speed obtainable from sunlight was not fast enough for the Lineups. They were going to illuminate the sail with their own artificial sunlight.

  "Here comes the
laser over the horizon," Gus said. He was wearing a modified battle helmet and was watching the scene in the infrared through the helmeyes in the top of his helmet. "I can't see the laser beam from the output mirror, but I can sure see the scattered light glow from the laser light bouncing back and forth between the two mirrors."

  Maury's helmet didn't have a helmeyes, and all he could see was two flat mirrors orbiting slowly overhead. The distant sail started moving as the gigawatts of laser power from the orbiting atmospheric laser bounced off it, pushing it outward to the asteroid belt, carrying its single passenger.

  "There goes the first interplanetary Lineup," Gus said. "At the rate the sail is accelerating, the Lineup will be there and replicating in a few weeks. Then watch out, asteroid belt."

  "How is it going to stop once it gets to the asteroid belt?" Maury asked. "Is there a laser there, too?"

  "The sail going out is actually in two pieces," Gus said. "An inner portion that carries the Lineup in a harness, and an outer ring-shaped portion. When the sail gets near the asteroid belt, the two parts are separated. The laser light being sent from Mars pushes the ring-shaped outer portion faster than the inner portion carrying the Lineup, so they drift apart. Soon, the laser light bouncing back from the ring-shaped mirror is striking the inner sail from the other side. The focused laser light reflected from the large ring sail is nine times brighter than the laser light coming directly from Mars, so the inner sail slows down and comes to a halt in the asteroid belt."

  "I still don't get it," Maury said.

  "There is a good book in the library files that explains it all," Gus said. "It's a science fiction novel, but there are diagrams in the back explaining how the multiple sail concept works. I think the title's Rocheworld ... can't remember the name of the author."

  "YEARS OF work made worthless," Viktor said sadly as he watched the slush drip out the ends of the hundreds of coring tubes still stacked in the storage racks. Ernest Licon came over from where he had been supervising the crew that was dismantling the core storage building preparatory to moving it to a safe place off the polar caps. The distant horizon was covered with millions of Lineups eating their way toward them. Above the Lineups spiraled clouds of flutterbats, processing the gases released by the actions of the Lineups and the groundworms. In polar orbits overhead passed thousands of large reflector mirrors, turning as they orbited to keep the region where the Lineups were working flooded with sunlight even though it was the dead of winter.

  "At least you got pictures of every core," Ernest said.

  "But the whole idea was to establish a chronology of ice and dust layers so that any future cores could be rapidly dated," Viktor said. "With the Lineups digging up the polar regions, there is no need for a chronology."

  "We are all having to make sacrifices," Ernest said.

  "I know," Viktor said sadly.

  "You had better get to the hopiter pad and get out of here," Ernest said. "Although the Lineups like working under the equivalent of twenty Suns, your Marsuit can't handle it. We'll all have to be on our way before the wave of Lineups gets any closer. I'll see you at the 'bomb shelter' in Mutchville when my crawler convoy gets there."

  "Don't be late," Viktor said. " 'Splat Sol' is only twenty-five weeks away."

  ORBITING low over Mars, skimming through the upper regions of the atmosphere, were eighteen lasers, soaking up the energy stored in the sunlight-excited carbon dioxide molecules and turning it into eighteen beams of ten-micron laser light. The mirrors on the lasers were three kilometers in diameter—big enough to send their powerful beams all the way to the asteroid belt without spreading. There, the beams were picked up by eighteen similarly sized ring-shaped mirrors anchored behind eighteen one-kilometer-diameter asteroids. The ten terrawatts of repetitively pulsed laser power in each laser beam were focused onto the rear of each massive nickel-iron asteroid, mining it into a crude rocket. First a short pulse would turn a thin layer of metal into a thin cloud of vapor, then a longer, stronger pulse would explosively heat the vapor, pushing the asteroid along. Although there were Lineups riding along on the structure to adjust the focus for steering, the system was designed as a self-steering beam-rider, and there was little for the Lineups to do until the last few sols, when they would tie the asteroids together with diamond-fiber cables into a long metal arrow aimed at Mars.

  "TWENTY-four hours to Splat Sol," Gus said. "Is everyone out of the volcanic regions and into shelters?"

  "Olympia, Tharsis Saddle, Elysium Saddle, and Hellas Basin are all deserted," Maury reported. "And of course the polar bases are closed down because of the Lineup activity there. We have Phobos and Deimos crammed to capacity, since they'll be the safest places. Everybody else is in underground shelters at Mutchville, Sinai Springs, and Melas. Some people wanted to stay at Isidis, but I felt that was too close to Hellas."

  "All we can do now is wait," Gus said, strumming his fingers nervously on the table at the Too Mutch bar. The large flatscreen on the wall had an image of the approaching string of asteroids taken from a telescope on Phobos.

  "Good thing we have lots of beer," Maury said, taking a sip. He looked at the flatscreen. "How come the asteroids are in an arrowlike configuration? I thought they were supposed to be lined up in a row."

  "By putting a couple off to one side at the end, the Lineups hope to make a hole shaped like a butterfly," Gus said. "The 'wings' will be northeast and northwest. That will give us more sunlight down at the bottom."

  "Let's hope it works," Maury said.

  "They've been doing things right so far," Gus said. "They're only partially done at the poles and we already have sixty-five millibars of oxygen and a total pressure of 125 millibars here in the lowlands at Mutchville."

  "Some crazies have even gone out for a few minutes with nothing but Turner Turbomasks on," Maury said. "I was going to make a law against it, but decided not to. Let 'survival of the fittest' operate to weed out the stupid ones."

  "I guess the best thing for me to do is get plenty of sleep," Gus said. "Hopefully there won't be any emergencies tomorrow, but if there are, I need to be fresh."

  "I think I'll have another beer, first," Maury said. "See you in the conference room tomorrow."

  "SOMEHOW, this just doesn't feel right," Gus said as he watched the large flatscreen in the conference room.

  "What do you mean?" Chris asked.

  "The Lineups are doing all the work for us," Gus said. "All we're doing is sitting around on our duffs, drinking beer and watching television, while the Lineups are making us a brand-new world—out of their world—and handing it to us on a silver platter."

  "I sort of agree," Jay said. "But we originally were planning on doing it all on our own."

  "And they are doing it hundreds of times faster than we ever could," Chris said.

  "That's a good close-up shot of the arrow coming in," Maury said. "How did they get that one?"

  "Somebody took an orbiter out from Deimos in a high elliptical orbit a few days ago so he could travel along with the arrow for a portion of its track and get a good picture," Jay said.

  "Say!" Gus yelled. "There are Lineups still riding on the asteroids!" He grabbed the controls to the flatscreen and zoomed in on a diamond cable. There was unmistakably a Lineup segment moving along the cable. "There's another ... There are dozens, hundreds of them! Splatdown is only two hours away! They're going to be killed!" He grabbed a communicator. "Maury, quick—what's the channel for our optical cable link to the Lineup enclave?"

  "Forty-nine."

  Gus punched the icons on the screen of the communicator and spoke into it. "Hello! This is Gus Armstrong calling Kipape."

  There was a short pause, then came a reply. "Replying to Gus Armstrong is Kipape-bypepo-tumuro-badepi."

  "Some of your people are still on the asteroids!"

  "Remaining on the string of asteroids are 648 segments."

  "They must be taken off!"

  "Remaining of segments on asteroids until im
pact is plan."

  "They'll die!" Gus yelled, frustrated. "We humans can't allow the Lineups to sacrifice their lives for us!"

  "Sacrificing of lives of segments not possible. Having of lives of segments not."

  "They're not alive?" Maury blurted. "They certainly act plenty alive to me."

  "I've always been suspicious," Chang Lu said. "Ask them if they are artificial life forms—robots."

  "Are the Lineups artificial life forms?" Gus asked. "If so, who made you and when?"

  "Making of Lineups by Masters many cycles ago."

  "That explains many things," Jay said. "But that means we asked permission of the wrong people."

  "Where are your Masters?" Gus said into the communicator. "We want to talk to them."

  "Existing of Masters here at this time not."

  "They are caretakers of the life forms until the Masters return," Jay said. "But the Masters didn't figure on one of the life forms learning to talk and giving orders to the Lineups. They won't recognize the place when they get back."

  "Tell me about the Masters," Gus ordered.

  "Telling about Masters permitted not."

  "We'll have to work on that later," Gus said, taming off the communicators. "We have a hole to dig. I still don't like the idea of those Lineups going with it, robots or not."

  CIRCLING out in space, the well-shielded eyes of orbiting cameras watched the arrowlike string of asteroids plow down through the thickening Martian atmosphere and strike Alpheus Colles at the bottom of Hellas Basin. The strike had been timed so that both Phobos and Deimos were on the other side of Mars where they were protected from the X rays emitted by the shock-heated atmosphere compressed ahead of the leading asteroid. There was a gigantic thunderclap as the air rushed in to fill the vacuum in the hole punched through the atmosphere.