Barnard Banger in interstellar mode cruising past Gliese 065 A
The notoriously volatile-poor Barnard's Star has remained an independent system since its founding. While never a site of great prominence, its age has allowed it to accumulate some wealth.
This wealth gave rise to the idea of importing volatiles, particularly hydrogen and nitrogen compounds. These inexpensive compounds were needed by the gigaton to be truly useful. (A 10km diameter, 50km long O’Neill cylinder could require almost 4 billion tons of nitrogen for its atmosphere.) However, the expense of interstellar transport made it questionable if it would ever be feasible to deliver useful masses of such low-cost volatiles to Barnard’s Star over interstellar distances.
The answer depended on the time, place, and technology. Archai could and did operate grazer wormholes to move stellar masses of material, but they were Archai. Normal economics and technological limits did not apply to them. For modosophonts in Barnard's Belt, they were much subject to greater restrictions. And, usually, the more advanced technological solutions were the more expensive. Wormholes were one answer, though they required large amounts of mass and Archai buy-in. Beamrider ships were another, but required large supporting infrastructures and were less suited for pushing gigatons to the stars. Conversion drives could do the job, but were not trivial technology for modosophonts.
Tethys Tourist Trap, a Barnard tourism company with a range of entertainment facilities in Barnard’s Belt that hosted some interstellar visitors (in addition to domestic tourists), had hoped to expand its resorts and theme parks in the early 8th Millennium but ran into shortages of volatiles. Its business development division ran an intensive series of trade studies on various volatile creation and import schemes and came to an interesting conclusion: using modern manufacturing techniques, relatively simple starships might be able to deliver volatiles economically over modest interstellar distances.
The transit time for such transport - centuries at low percentages of light speed - fell outside TTT’s timeline for resort and theme park expansion, so the idea of importing volatiles for TTT was shelved. However, a number of business beings in TTT were sufficiently interested in the trade studies to invest in a trial of the proposed “ultra-low cost interstellar freighter.” The ULCIF's drive and Barnarders’ penchant for alliteration led the ships to be named “Barnard Bangers.” The first company to build them, a spinoff from TTT, was predictably named “Barnard Bangers, Inc.”
DESIGN AND HISTORY
The Barnard Banger is a class of starships designed for low cost (by starship standards), simplicity (by starship standards), and low technology (by starship standards). Despite a goal of low technology, it is partially enabled by advancednanotech and Von Neumann mining technology that makes it considerably easier to process and assemble such huge masses. The ships were large compared to singleships, but much smaller than many interstellar warships and were dwarfed by worldships, generation ships, Creighterships, and other interstellar behemoths.
The first Barnard Banger, named "Bangers and Mash," embodied most of the concepts used in later, larger Barnard Bangers. It consisted of a stern drive unit, a payload of ice, and “balance of ship” features like control systems, maintenance bots, and a modest power plant. The construction method of the first ship also set a standard.
Barnard Bangers, Inc. staked a claim on one of the inner Oort cloud comets of the Solar system, a volatile rich star system close to Barnard's Star. Despite the Haloists in Sol's Oort cloud, there were still countless comets to be claimed. Barnard Bangers, Inc., picked a modest comet ("Lake Mead") averaging 7 kilometers in diameter so as not to generate jealousy among the locals. A Grape Ship delivered a nanofac and fusion power system to Lake Mead. This industrial package began assembling the first Barnard Banger in 7533AT, and at the same time began disassembling and processing Lake Mead into large stores of separated chemicals. Water was, of course, important, but perhaps more important were the diffuse deuterium and lithium in Lake Mead, a few million tons of each.
The drive section grown by the nanofac's assemblers was a very large, external fusion pulse drive. It was a momentum-limited pusher plate design that would not have looked too alien to first decade AT pulse drive designers. The structure was black, coal black, as a result of being made from graphite-graphite composites, diamondoid, and other carbon compounds extracted from Lake Mead's water-rich, carbonaceous bulk. Above the two-stage, lengthy pusher pistons, the drive section also had voluminous storage bays for the "propulsion units;" tanks for liquid water to protect the pusher plate from ablation; and the multiple reactors of the fusion power plant. Because "Bangers and Mash" was intended to deliver over a cubic kilometer of water ice (a gigaton, exactly) to Barnard's Star at 2% of light-speed and with 0.01G of acceleration, it used propulsion packages with 1-megaton yields. The enormous propulsion section's storage bays held a gigaton of propulsion units to deliver 0.04c delta-V.
The propulsion units were a study in both elegance and crudity. Their core (for Bangers and Mash) was 200kg of lithium deuteride in an Ulam Teller package, with a compact, laser-triggered fusion fuse to avoid any need for fissile materials. The crude aspect was that the propulsion units eschewed efficient heavy metal (uranium, tungsten, lead) radiation mirrors, tampers, and reaction mass in favor of much more massive and less efficient alternatives made of light elements (carbon, hydrogen, oxygen, nitrogen) available from Lake Mead. And then each 10-ton (in total) "physics package" was wrapped in 2,500 tons of polyethylene (carbon and hydrogen from Lake Mead) and water ice (also from Lake Mead), while the kilometers-wide pusher plate discharged 2,500 more tons of water (Lake Mead) before each detonation to protect the plate from ablation and provide more reaction mass. Bangers and Mash would launch with 200,000 propulsion packages using a modest 40,000 tons of deuterium and lithium, and it was made entirely of in situ-mined materials. No purchases of amat or helium-3 were required.
After acceleration, empty portions of the drive section were dismantled and converted to additional propulsion charge reaction mass. During its 275-year cruise, the pusher plate was also folded up like a flower bud to minimize its exposure to interstellar dust and debris. It would only be expanded for deceleration.
The payload of a Barnard Banger was volatiles, often water but sometimes ammonia or other nitrogenous compounds. Bangers and Mash carried a gigaton of water ice, but it wasn't a simple lump of cometary ice. Cometary ice was porous, weak, and fragile. A Barnard Banger turned its payload into a key piece of its structure. In the case of Bangers and Mash, that 1.1 cubic kilometers of ice was recast into an engineered block modified with about one percent of gelling agent (a heavier sugar-alcohol derived from Lake Mead hydrocarbons) and one percent of carbon fiber with a polar surfactant. The ice was also swathed in multi-layered insulating blankets of Kapton (Lake Mead carbon, nitrogen, hydrogen, and oxygen) coated with microscopic amounts of aluminum (found in Lake Mead dust grains); the widely spaced insulation also served as a Whipple shield against dust.
After 2 years of accelerating to 0.02c, Bangers and Mash's bot maintenance crew used heat from the power plant to re-cast the ice into an enormously long pagoda (inside a cylinder of ultra-light insulation film). The arrangement of thousands of disks of reinforced ice, spaced by pillars of ice, was the ultimate expression in Whipple Shields and only possible in free fall. After centuries in transit, the shield material was re-condensed into a solid, carefully structured block before the ship decelerated into Barnard's Star.
With the successful acceleration of Bangers and Mash, which essentially proved the ship's systems, Barnard Bangers, Inc. continued converting Lake Mead into further Bangers of increasing size. Each successive launch doubled in mass until a total of 6 Bangers were in flight by 7603AT. These eventually delivering a total of 63 gigatons of volatiles to Barnard's Star and reduced Lake Mead to a small clump of dry, useless dust.
When the last of the Bangers decelerated into Barnard's Star, an assessment of the project was possible. The investors had received 63 gigatons of volatiles, which was enough to start several sizable habitats or meet the needs of billions of individuals in fairly spartan closed life support systems. However, context was important for determining the value of the volatiles. The Barnard Bangers, Inc. plan had drawn some interest and competitive start-ups. The most nefarious was a Sunminer house who scooped hydrogen from Barnard's Star, combined it with oxygen from the minerals in Barnard's Belt, and sold the resulting water much less expensively than was available from the Sol system. Those sales came with contracts that, by 7,825AT, had locked much of Barnard's population into an odious web of sociopolitical control. The arrival of successive Bangers with their expensive (but no-strings-attached) water and nitrogen upset to the Sunminer water monopoly, as did the Barnarders' independence-minded attitudes.
In another system, the imports were unlikely to have been worth the trouble. One of the economically lethal factors was the slow delivery. In most cases, more advanced/expensive ships could have made multiple trips or delivered more volatiles in a shorter period, thus reaping more profit despite higher fuel and construction costs.
But the Barnard Bangers were an interesting concept that caught the imagination of Backyarders, middle tech societies and and Lo Teks across the Known Net. They were ships that could be assembled with a minimal number of technologies, little in the way of expensive fuels like amat (often fusion fuels were extracted in situ from a comet), and only required a modest nanofac to start production. Since then, the ships have appeared in backwater systems across the Nexus. Few have been applied to any commercial application (and fewer still were commercially successful), but seem to entertain hobbyists and have added a new tool for delivering large quantities of materials over interstellar distances.