Casindra Lost

by Marti Ward

  He was surprised that he hadn’t been called to the bridge for their arrival at PTL4. Of course, Al was able to monitor him in the cabin, knew his routine, knew he would be on the bridge by 6… but still it was an important moment. Anyway, he would be on the bridge an hour before arrival, and would wait till he was there to ask Al for an update. That’s how a shift changeover normally worked, although this was the first time anyone had been cycling shifts with an AI!

  He walked briskly downhill to the bridge – they were at 50% reverse thrust at the moment, making for a comfortably increased gravity. The sliders whooshed open and closed as he passed through and took his chair, sweeping his gaze across the viewscreens and then the displays that wrapped around the command chair. “Al, status?”

  “Good morning, Captain! All systems at nominal! Trajectory is on target for arrival at PTL4 on schedule at 07:00. The existing mirror array has been detected in a 49km orbit around PTL4, and we are set to orbit at 100km.”

  The PTL4 Ford-Svaiter mirror was a 3x3 array of smaller antimatter reflectors, three dropped off by each of three unmanned probes – and used for their message drones as well as their own return. The principle went back to the early days of radio astronomy when first two or three dishes were combined, and eventually hundreds of dishes, either on the ground or at a Lagrange point. The probe mirrors appeared as blue gray specks from this distance – they would be pushed apart and then reconnected in expanded form using a quite different technology based on nanosilc, essentially the same as the SECASM employed on Casindra and its EmProbes.

  “Thank you, Al! Please display gate array at 50x magnification.”

  The cross-sectional area of the 3D cavum within the multidimensional wormhole was the geometric mean of the areas of the gate’s mirror and the vessel’s mirror. In practice, that meant the gate mirror should be at least as large as the ship’s. For a safe stable navigable trajectory, the engineers had determined, more or less by trial and error, that the cavum should be at least 4 times the diameter of the vessels – in fact they aimed for 8 to 10 times that for the EmProbes and even more for the higher risk set-and-forget message drones that didn’t have the onboard intelligence to make corrections and so used the same size mirrors as the much bigger EmProbes to gain that extra margin. But there was still a risk of collapse or perturbation failure at those levels.

  Their current task was to push apart nine 100m diameter mirrors that had unfolded from the 7m diameter unmanned probes into the anchor points for a 1000m diameter gate.

  If Sideris ever wanted to go home, this was critical. The Casindra’s SECASM and the upgraded gate array would each need a minimum diameter of 500 meters to accommodate the 50m diameter LETO with its attachments all pulled in tight around it for the week in cavum, while the projected 1000 meter system would allow them to stay expanded and maintain centrifugal gravity during transit. The next two missions would triple the gate array size again, as well as each bring 500 pioneers to help establish settlements and mining facilities. This final expansion would allow it to accommodate the new 10000 passenger Asteria class ships that were being built.

  For Sideris another obvious risk was whether he would have the food and life support to survive a trip back to Sol if forced to use a suboptimally sized mirror. A key and perhaps more critical effect of the larger mirrors and cavum area was that transit time reduces proportionately too – and stability increases correspondingly as well. The mirror being built into asteroid 243 Ida at Sol-Jupiter L4 would eventually have over 20 times the diameter for a hugely reduced transit time that turned days into minutes for a fleet of 10 of the new Asteria class ships – the exact duration would depend on the precise specifications of the SECASMs they ended up deploying. They wouldn’t get home that quickly though with just the 3km mirror being put together by the precursor missions – but of course, the plan was for the Solar Horizons fleet to stay.

  “Please put viewscreens into planetarium mode: dim Paradisi and color code in-system bodies for distance, scaling for log diameter!”

  The lights dimmed and the ceiling, floor and walls shimmered dark blue. A red-green-blue near-far color scale appeared immediately as the sun to the left of the forward screen dimmed. The starfield resolved quickly to show in greens and yellows the expected three Goldilocks planets. Al had also used the 3D capabilities of the screens to provide a scaled depth model.

  Although Casindra was in Tenebra’s orbit, Tenebra was as far away from the ship as Paradisi, the sun that gave life to this system. On the port viewscreen, Tenebra seemed little different from any of the stars. Based on the probe reports, this heavy Mars-sized planet, the third from the sun, would be the least useful of the three planets Goldilocks with human tolerable gravities, although it might be worth mining rare minerals there.

  New Eden showed up behind Tenebra, the next closest planet to the sun, on the same screen, in gold quite appropriately – as Earth’s twin and the planet that was to be settled, it was the paradise that all the hype was about! Finally, behind, on the opposite side of Paradisi, was Ardesco, the planet in closest orbit to the sun. According to probe reports, this slightly bigger, slightly heavier planet was going to be the gold mine, a source of industrial and precious metals, as well as the critical nuclear fuels thorium and uranium, but a hot and difficult planet to work on.

  The gas giant, Praelium, was furthest away from Casindra but still obvious on the screen, but he was looking for Petra – smaller and younger than Mercury, it was more jagged than rounded, it was more asteroid than planet. But it was much heavier and chock full of heavy metals, and was so far the outermost of the known planets in the Paradisi system. There it was – he’d spotted its cyan halo on the starboard viewscreen. Petra was to be mined by self-propagating autonomous robots – von Neumann machines. Depending on who you talked to, his primary job on this mission was to seed it with the automatons he’d brought, and then they were meant to set to work, mine the rock, build more automatons, and stockpile resources needed by the coming fleet to build its new home.

  He could simply send off the automatons to Petra as planned, or he could go visit. Given the alignments of the planets at this point, it didn’t look like it would make a lot of difference fuelwise or timewise, given the heavy fuel trajectories he would be using throughout the mission in any case.

  “Al, please calculate optimum order and minimum fuel cost for Casindra to visit Ardesco, New Eden, Tenebra and Petra and return here to PTL4, including fuel costs for mandated message drones and the Petra-seeding probe. Compare with the alternate plan of not visiting Petra, and determine the best point to send off the seeding probe in this scenario. Compare with minimum time budgets using double minimum fuel and using 80% available fuel, planning for at most two days at Petra while ensuring that we have two to three months for New Eden, and that the Ardesco and Tenebra visits include seven to fourteen days in low orbit.”

  “Acknowledged! I will see if I can fit Petra into the schedule!”

  Al’s response was surprising both in its informality, and in its capturing the essence of the command. Sideris was intrigued to see whether it came up with a sensible and convincing solution.

  The Cavitrans stopped with their usual jerk, and the PTL4 mirror array was visible on the port viewscreen, perfectly aligned for sending a message drone. Al’s formal report confirmed this, “We have arrived at the PTL4 Ford-Svaiter Mirror. Preparing to initiate deployment of the mirror extension. The Captain’s earlier request to delay sending arrival message until after deployment of mirror and automata has been triggered – Message Drone 3 has not been dispatched. Please note that waiting until we reach Petra to dispatch Message Drone 3 would be in violation of standing orders. Unable to reconcile orders and schedule Message Drone 3 as required. Updating logs and scheduling for immediate launch.”

  “Belay that! Schedule as follows: Launch FS Mirror Upgrade Mission; if previous proposal to visit Petra is feasible, then on validation of upgrade, we will update and launch Messag
e Drone 3; if Petra visit is infeasible we will proceed with launch of Petra Seeding Mission and include the parameters for dispatch with Message Drone 3.”

  “Message Drone 3 launch sequence suspended! Captain Sideris, there is a risk that the upgrade mission will not be successful. Standing orders are to send message drones before undertaking any high-risk mission.”

  “Al, the upgrade of the mirrors is low risk. The message drone could be sent using either the old mirrors or the new mirrors alone, but it will arrive earlier if delayed until it can be launched with the upgraded array. Please compute arrival times using existing and upgraded arrays, and also compute the risk of losing so many mirrors that we can’t open a wormhole with other available mirrors.”

  “Acknowledged! Message Drone 3 will take 36 days using the current array, and 9 days using the updated array. Risk of losing 75% or more of the mirrors in the updated array is estimated as less than 1% based on upgrade history at SJL4. Using Message Drone 3 in combination with SS Casindra’s SECASM would be feasible with an expected time in cavum of 144 days and a risk to Casindra of less than 10%. Risk of damage to SS Casindra or Message Drone 3 SECASM during upgrade is estimated at less than one in a hundred. Expected time for message receipt is optimized if the upgrade mission is scheduled ahead of the message drone.”

  “Please proceed with launch of PTL4 Mirror Upgrade Mission, and then report on the options explored in relation to Petra.”

  “Mirror Upgrade Mission launched… Petra visit is feasible given mission parameters while maintaining the 20% fuel reserve. Message Drone 3 update and launch has been scheduled for automatic action upon successful completion of mirror upgrade tests… Minimum fuel trajectory without visiting Petra is 2221 days. Minimum fuel trajectory with a visit to Petra is 4427 days. Both of these options would use around 2% of our fuel, but would exceed the targeted mission of 1095 days, as well as the extended mission duration of 1460 days. Solutions for 4% fuel usage include 1184 days excluding Petra and 1392 days including Petra…”

  Sideris interrupted, “That’s fine, thank you Al. I understand you have found solutions that satisfy apart from the non-critical criteria identified?”

  “Many solutions exist that use around 5% of fuel, include Petra, and fit the 1095-day maximum mission duration and minimum orbit parameters. Calculations do not take into account life support or cryogenics which will use additional fuel, as this is a function of mission time rather than trajectory or Cavitran usage.”

  “Are there similarities between these 5% solutions?”

  “These 5% fuel solutions all involve visiting Tenebra first and Petra second…

  It took only an hour for the two of them to explore quite a few options that visited Tenebra and Petra first and New Eden last, and distributed extra orbital time proportionally across the three inner planets in different ways. There was sufficient flexibility that they could embark on a plan now and adapt it on the fly – and so the main criterion they used to select between the possibilities was maximization of flexibility.

  “Please include this plan in Message Drone 3 for dispatch on completion of mirror upgrade tests.” Sideris paused for an instant then continued in a thoughtful tone, “Al, I’m really impressed! You dealt with a complex variable weight optimization problem and compared with background mission parameters, and identified and relaxed less critical constraints to find solutions that satisfied the mission requirements even though they didn’t quite meet my specification.”

  He paused again, looking at the frozen traces of the animation. “I am also impressed with your animation and the way you took my earlier coding for the planets, adding your own legends and usage bars at your own discretion, and using trace ageing.”

  “Acknowledged!” Al obviously wasn’t any better at taking praise than he was…

  Simba

  9 July 2075 18:20

  Simba was getting bored! What she wasn’t getting was enough exercise!

  Their cage was rather small. Both Simba and Samba could leap from anywhere to anywhere, but there was only one sad stump worth climbing. Simba had tried leaping high onto the rubbery bars, and sniffing at everything interesting, but there wasn’t anything of much interest.

  She felt quite unbalanced in this place. On the one paw, she could leap twice as far as usual; but on the other paw, she somehow felt weak; and at the tail she’d sometimes feel a tilt towards the back of the cage, and be startled into a spring towards the door.

  Simba had tried a bit of throw and chase, but her mother had taught her not to play with her food, and there wasn’t anything else to play with. She batted the last morsel around on the rubbery floor while debating whether to spring for some more – she’d discovered that leaping up and catching a particular bar would achieve just that! Normally, though she just accepted what came.

  It was about time for the gray’n’gold human to visit – she felt neglected, and he seemed to be a bit late today for his evening visit. Normally she’d still be eating.

  For today, she’d planned a real performance: she’d rub across the bars right in front of him, as close as she could get, and give him the hint that those could be his legs she rubbed against; then she’d stand up tall against the bars, pushing her face into them as far as it would go, and give a plaintive meow – that always seemed to get people’s attention. Although, as with Samba, she felt she could often catch gray’n’gold’s attention without having to say anything. They did seem to be developing an understanding – if only she could do something with that and get out of here!

  Sure enough, the sliders whooshed open and there he was. She’d already started putting her plan into action before they’d even closed again. Samba had had the same thought and approached the gate too, rubbing against the bars. The human’s eyes flickered between them and she responded by stretching up against the bars and catching them with hers. She gave two plaintive calls for good measure, maintaining eye contact, sensing at him that he needed to let her out, that he wanted to let her out… She sensed in him that it was true and right and the way things should be.

  He turned from her to a window near the door. She dropped back to all fours, and felt her heart fall too – he wasn’t going to open it; he was going to leave early!

  But then she heard him talk through the window, and the cold voice replied from nowhere. The doors whooshed open, but he didn’t leave – it was the cold one! Gray’n’gold focused on the cold one, although he talked to the voice that wasn’t there. She sensed him trying to dominate the cold one – but the cold one had no sense. She sensed him pleading, placating, submitting – but the cold one had no sense.

  “Meow,” she added her plaintive voice to the argument.

  Gray’n’gold turned back to look at her… came back to the cage… opened it… and stepped back. The cold one just stood there, cold and senseless as usual. Ignoring it, Simba stepped out in front of gray’n’gold, rubbing across his legs and heading towards the door for a quick sniff in that direction, then rubbing by the back of his legs and entwining around them. Samba came out too, and brushed past gray’n’gold on the other side, brushing behind him to go and sniff at cold’n’senseless. Was Samba going to try to claim this cage-like thing as part of their domain?

  Yes, Samba gave it the full works, brushing and entwining around the back of cold one’s bar-like legs and along its cold bar-like feet – with no more sense than they got from the bars or the stump in the cage! Samba put his legs on its foot, and looked up into its windowed face. Still no sense! He leapt over one foot then the other in a kind of double bounce, and streaked to the door of the compartment, sniffing around it. Good idea! Simba, joined him to experience the full flavor of the scents that wafted there. There were not just the usual rubbery, sweet, unreal, smells of the human domain, there were interesting food smells, and there were also strange stormy smells.

  Simba left Samba at the door, rubbing past the back of cold’n’senseless and gray’n’gold, who were still standing awkwardly
near the cage. She moved across to the skydome box. She didn’t want to give anyone any ideas about putting her in it, so she was careful to stay away from the opening – concentrating on all the vines and branches that surrounded it with many different colors and sizes, but all with the same sweet smell. She raised herself up and batted at one experimentally. Interesting, but she didn’t think it would support her weight – even as light as she was these days. So she headed back to gray’n’gold to say thank you.

  Simba stopped alongside him in an alert upright sitting position, and then stretched up to place her paws on his knee! He bent down and let her sniff his paw, before moving it around to groom her head, to scratch behind her ear, to stroke the full length of her back, and her tail, as she arched into it. She purred comfortably in acknowledgement. This was much better!

  Eventually gray’n’gold stood up and purred something, indicating that it was time for him to go. Before he or cold one could have any thoughts about putting them back in the cage, she wafted around and behind him and headed over toward the domebox, circling a likely spot before curling up and conveying her message: This is where I am going to stay tonight.

  Samba came over and joined her, performing a similar routine.

  Chapter Three

  P–Praelium L5 superhighway

  Interplanetary Superhighways – NASA (public domain)

  http://www.jpl.nasa.gov/releases/2002/release_2002_147.html

  Sideris

  3 October 2075 06:00

  Exploring could be boring! Spending months alone in space was hardly the exciting adventure people thought it was – that’s one reason most people ended up cryosleeping through it. A few minutes plotting the course, as captain of a manned mission, was followed by a few months of being a passenger. And in the present case, it was Al plotting the course – and he did it brilliantly, exploiting low energy transfers between Interplanetary Superhighways within the Paradisi Interplanetary Transport Network.