/sci/ - Science & Math

[Colonel Coffee Mug !phJ7yIcs.Q No.3214205]

/sci/ is so stale right now. Interstellar propulsion thread.

Noted polymath Charles Pellegrino and Brookhaven physicist Jim Powell have an innovative antimatter powered starship design called a Valkyrie. They say that current designs are guilty of "putting the cart before the horse", which create ships that are much more massive than they need be. Their "spaceship-on-a-string" starship is capable of accelerating up to ninety-two percent the speed of light and decelerating back down to stationary. At this velocity, relativity mandates that time on board the ship will travel at one-third the rate of the stay at home people on Terra (actually it's closer to 1/2.55). They figure this will be adequate for visiting stars up to about twelve light-years from Terra, without using up excessive amounts of the crew's lifespan.

Dr. Pellegrino served as a scientific consultant on James Cameron's Avatar movie. The interstellar vehicles seen in the film are based on the designs of Pellegrino and Powell's Valkyrie rockets, fused with Robert L. Forward's designs. I figured this out when I noticed that the Avatar starship had the engine in the front, which is a unique feature of the Valkyrie.

>From Flying To Valhalla by Charles Pellegrino (1993):

...For propulsion purposes, microfusion bursts triggered by antihydrogen-hydrogen annihilation (possibly with a component of lithium added) will prove efficient up to ship-cruising speeds approaching twelve percent the speed of light, owing to jets of relatively slow, massive particles. Above twelve percent lightspeed, propulsion shifts from antimatter-triggered fusion jets to straightforward matter-antimatter annihilation, which produces a lower mass thrust than fusion, but provides particles with the high-exhaust velocities necessary to push the ship to a high fraction of lightspeed.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214219]

How much antimatter might be needed for a trip to Alpha Centauri - assuming that Asimov Arrays or something very much like them will eventually provide humanity with the excess energy required for its large-scale production? We have estimated that the fuel stores (both antimatter and matter combined) might be equal to roughly half the mass of the rest of the spacecraft, or about one hundred tons (to assure "burning" of all available antimatter, an as-yet-undetermined excess of matter will be required).

Others have been more pessimistic, including an earlier study by space scientists Donald Goldsmith and Tobias Owen which yielded an estimate that a journey to Alpha Centauri would require four hundred million tons of matter-antimatter fuel. Such estimates arise from assumptions that the spacecraft will be huge, with powerful engines mounted in the rear. Everything forwards of the engines becomes, in essence, a massive, rocketlike tower, requiring enormous amounts of shielding from the rocket's gamma ray shine, supplemented by complex (and massive) cooling systems to shed intercepted engine heat (and a traditional rocket configuration must absorb most of the head-depositing gamma rays, even if they do, like X rays, have a tendency to pass through things). The addition of each layer of shielding and cooling equipment placed on top of the engine becomes increasingly prohibitive as ship mass increases, requiring higher burn rates, which in turn requires more cooling and shielding, which increases ship mass and burn rates, and so on.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214220]

With our elongated, two-crew-member ship on a string, gamma shine and heat are spilled directly into the unfillable sink of outer space. A pulling rather than a pushing engine eliminates most of the structural girders that would not only, by their mere existence, add unwarranted mass, but would multiply that mass many times over by their need for shields and coolers. Valkyrie, in effect, is a fuel-efficient, twenty-first-century version of today's "ultralight" aircraft...

...Since antimatter and matter annihilate each other on contact, releasing enormous bursts of energy from literally microscopic amounts of propellant, you cannot simply fill a shuttle tank with liquid antihydrogen and let it slosh around inside.

The only storage method that has a hope of working is solid antihydrogen, supercooled within one degree of absolute zero (within one Kelvin of -273 degrees C). At this temperature, antihydrogen condenses into "white flake," with an extremely low evaporation rate.

Particles of solid antihydrogen will be suspended and held away from the "pod" walls, probably by electrostatic forces and/or magnetism. According to our latest models, near 0.0005° K, antihydrogen should be sufficiently stable as to allow, in the form of matter-antimatter micropellets or wafers (we are presently working to determine which design, layered pellets or wafers, will provide optimal thrust). With one-fifty thousandth of a degree Kelvin, matter-antimatter storage becomes thinkable because wave functions do not overlap enough to produce an appreciable reaction, at least in principle.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214226]

Since the pions and muons are acting only against a magnetic field, they can propel the Valkyrie without ablating or wearing down the engine walls (as does space shuttle propellant, with the result that the engines must be rebuilt after every flight, and eventually thrown away). However, gamma rays emitted by the decay of neutral pions will knock atoms out of position in structures near the antimatter reaction zones, making the material stronger, yet brittle. One solution is to add structures called shadow shields wherever practical. (Shadow shields are nifty little devices already being used in certain very advanced nuclear reactors. They are a major component of Valkyrie, so stay with me and I will get around to describing them in just a few moments.) Another, supplemental solution is to weave most structures residing within four kilometers of the reaction zone from hundreds of filaments, and to send electric currents through the filaments, heating them, one at a time, to several hundred degrees below their melting point. Gamma ray displacements in the wires are thus rearranged, and the atoms can reestablish their normal positions. (ed. note: this is called "In-Site Annealing")
There appears to be nothing we can do to prevent the occasional transmutation of atoms into other elements. Fly far enough with your engines burning at full throttle, and your ship will turn slowly into gold, plus lithium arsenic, chlorine, and a lot of other elements that were not aboard when you left.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214224]

(And in practice?)

We do not know. It has not been practiced yet, and can only be verified by experimentation. Personally, carrying matter-antimatter pellets already assembled, even at 0.0005° K, gives me nightmares. I keep seeing a cosmic ray particle stopping at the matter-antimatter interface, giving off its heat, and triggering a horrible chain reaction... Jim says we can prevent that, but I am still opting for storing our antihydrogen in complete isolation from matter until virtually the moment it is needed. I am reminded of that scene from the movie version of 2010, in which Roy Scheider describes the aerobraking maneuver his ship is about to make through Jupiter's atmosphere. "It's dynamite on paper," he says. "Of course, the people who came up with the numbers on paper aren't here."...

...Upon warming, electrons and positrons self-annihilate to produce small bursts of gamma rays which, in terms of thrust, can be totally ignored. The positrons are there simply for stability's sake. The proton-antiproton pair, however, produce three varieties of elementary particles called pi-mesons...

...The charged pions and muons are the particles we want and when not being used below twelve percent lightspeed to immediately trigger fusion explosions (a matter of simply modifying the type of pellet or flake used), we want to simply bounce the pions off the outermost fringes of the engine's magnetic field, and thus steal whatever thrust they have to contribute, before a significant fraction of them have traveled twenty-one meters and shed part of their energy as useless neutrinos. The engine we have designed ejects pions and muons (and, at lower velocities, pion- and muon-triggered fusion products) along a diverging magnetic field nozzle to produce thrust, in much the same fashion as hot, expanding gases in a conventional rocket impact against the solid wall or pusher plate at the back of the ship, propelling the entire assembly forwards.

[Anonymous No.3214229]

Pick a good looking comet. Land on it, and nudge it into a slingshot off the sun that will fling you towards your target.

When the comet is a bit further out, no longer making a tail, set up your nuclear salt-water engine. Using fission as the power source, and the comets mass as propellant, continue accelerating to your target.

When you get near the target, figure out how much propellant you'll need to detach and slow the main part of your ship to orbit, dig that much out and leave the comet.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214237]

These new substances will be concentrated around the antimatter reaction zone, and it is important to note that advanced composite materials already coming into existence dictate that our Valkyrie, even at this early design stage, will be built mostly from organic and ceramic materials, rather than from metals. It is conceivable that expanding knowledge of composites can be taken into account by the time relativistic flight becomes a reality, so that the ship actually incorporates the transmuted elements into its filaments in a manner that ultimately results in structural improvements for a ship designed to essentially rebuild itself as it flies. Exploiting what at first glance seems to be a disadvantage (transmutation) is simply a matter of anticipating the "disadvantage" before you begin to build. It's the disadvantages unforeseen or unaddressed that will get you in the end.
The gamma ray flare from the engine dictates other major features of ship design. In particular, it has caused us to turn rocketry literally inside out.

Riding an antimatter rocket is like riding a giant death-ray bomb. An unshielded man standing a hundred kilometers away from the engine will receive a lethal dose of gamma radiation within microseconds. In designing spacecraft, even when considering propellant as efficient as antimatter, RULE NUMBER ONE is to keep the mass of the ship as low as possible. Even an added gram means extra fuel.
Here's how we can shave off many tons of shielding.
Put the engine up front and carry the crew compartment ten kilometers behind the engine, on the end of a tether. Let the engine pull the ship along, much like a motorboat pulling a water skier, and let the distance between the gamma ray source and the crew compartment, as the rays stream out in every direction, provide part of the gamma ray protection - with almost no weight penalty at all.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214248]

(ed. note: this should remind you of "Helios") We can easily direct the pion/muon thrust around the tether and its supporting structures, and we can strap a tiny block of (let's say) tungsten to the tether, about one hundred meters behind the engine.
Gamma rays are attenuated by a factor of ten for every two centimeters of tungsten they pass through. Therefore, a block of tungsten twenty centimeters deep will reduce the gamma dose to anything behind it by a factor of ten to the tenth power (1010). An important shielding advantage provided by a ten-kilometer-long tether is that, by locating the tungsten shield one hundred times closer to the engine than the crew, the diameter of the shield need be only one-hundredth the diameter of the gamma ray shadow you want to cast over and around the crew compartment. The weight of the shielding system then becomes trivial.
The tether system requires that the elements of the ship must be designed to climb "up" and "down" the lines, somewhat like elevators on tracks.
We can even locate the hydrogen between the tungsten shadow shield and the antihydrogen, to provide even more shielding for both the crew and the antihydrogen.
There is an irony involved in this configuration. Our "inside-out" rocket, the most highly evolved rocket yet conceived, is nothing new. We have simply come full circle and rediscovered Robert Goddard's original rocket configuration: with engines ahead of the fuel tanks and the fuel tanks ahead of the payload. Nor is the engine itself an entirely new creation.

It guides and focuses jets of subatomic particles the same way the tool of choice among most microbiologists guides streams of electrons through magnetic lenses. Valkyrie, in essence, is little more than a glorified electron microscope.
In addition to shielding against gamma shine and avoiding the absorption of engine heat, another major design consideration is shielding against interstellar dust grains.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214251]

Flying through space at significant fractions of lightspeed is like looking through the barrel of a super particle collider. Even an isolated proton has a sting, and grains of sand begin to look like torpedoes. Judging from what is presently known about the nature of interstellar space, such torpedoes will certainly be encountered, perhaps as frequently as once a day.
Add to this the fact that as energy from the matter-antimatter reaction zone (particularly gamma radiation) shines through the tungsten shields and other ship components, the heat it deposits must be ejected.
Jim Powell and I have a system that can perform both services (particle shielding and heat shedding), at least during the acceleration and coast phases of flight. We can dump intercepted engine heat into a fluid (chiefly organic material with metallic inclusions) and throw streams of hot droplets out ahead of the ship.
The droplets radiate their heat load into space before the ship accelerates into and recaptures them in magnetic funnels for eventual reuse. These same heat-shedding droplets can ionize most of the atoms they encounter by stripping off their electrons. The rocket itself then shuts the resulting shower of charged particles - protons and electrons - off to either side of its magnetic field, much the same as when a boat's prow pushes aside water.
The power generated by occasional dust grains should range from the equivalent of rifle shots to (rarely) small bombs. These detonate in the shield, harmlessly, far ahead of the ship. Fortunately, almost all of the interstellar particles likely to be encountered are fewer than 20 microns across (10,000 microns = 1 centimeter), and we should expect no more than one impact per day per square meter of Valkyrie's flight path profile...

[Colonel Coffee Mug !phJ7yIcs.Q No.3214253]

...One of the great advantages of a droplet shield is that it is constantly renewing itself. Put a dent in it, and the cavity is immediately filled by outrushing spray.

If a dust grain passes into the shield, many of the shield's droplets are bound to be exploded. Some of the scattered droplet fluid will be absorbed and recovered by surrounding droplets, but some fluid is bound to be hurled out of the droplet stream, which means that we must add the weight of droplets to be replaced to the ship's initial mass.

In addition to spare droplet fluid, our preliminary design calls for a spare engine. Both engines will be located at opposite ends of the tether. The forward engine pulls the ship along during the acceleration phase of flight. It also fires during the cruise phase, but only at one-hundredth thousandth of a gravity, keeping the tether taut and permitting recapture of forward flying droplets. At the end of the cruise phase, the rear engine kicks in for deceleration (as we cannot simply swing a ten-kilometer-long ship broadside to relativistic bombardment in order to turn the engine around and fire in reverse).

[Colonel Coffee Mug !phJ7yIcs.Q No.3214257]

In normal use, the rear engine is turned on only to decelerate the ship, or to maneuver the crew compartment into the center of the forward engine's gamma ray shadow. Nudging the crew compartment, from behind, to one side or the other will be necessary during major course changes, because the crew compartment, much like a water skier, cannot turn simultaneously with the motor that pulls it and might otherwise drift out of the protective shadow. A spare engine also provides some insurance against the chilling possibility of irreparable damage to the leading engine or, worse, a break in the tether. In the former case, identical engine parts could be ferried up and down the tether and exchanged as necessary. In the latter, depending upon where the break occurs, with careful rearrangement of the ship's components along the tether, the remaining coil can be safely used to finish the outbound leg of the mission.

At the end of the cruise phase, with nearly half of the ship's fuel exhausted, empty fuel tanks can be ground up into ultrafine dust, for dumping overboard (we see no reason to expend extra energy decelerating tons of equipment, no longer in use, which can easily be remanufactured and replaced at the destination solar system). At up to ninety-two percent the speed of light, the dust will fly ahead of the decelerating ship, exploding interstellar particles and clearing a temporary path (trajectories must be such that the relativistic dust will fly out of the galaxy without passing near stars and detonating in the atmospheres of planets).

[Colonel Coffee Mug !phJ7yIcs.Q No.3214268]

This fist of relativistic dust is the first line of defense against particles encountered during final approach. With the rear engine firing into the direction of flight, droplet shields will be come useful only for expelling heat from the rear engine, for along the tether, "up" has now become "down," and droplets can only be sprayed "up" behind the engine, where, traveling at uniform speed, they will fall back upon the decelerating ship. To shield against particles ahead of the ship, ultrathin "umbrellas" made of organic polymers similar to Mylar and stacked thousands of layers deep are lowered into the direction of flight. This is the second line of defense - against particles moving into the ever-lengthening space between the ship and the fist. The umbrellas will behave much like the droplet shield and, in like fashion, they will be designed with rapid self-repair in mind. Throughout the ship, repair and restructuring will be assisted (where such repair abilities as self-annealing filaments are not already built into ship components) by small, mouselike robots capable of climbing up and down tethers and rigging.

[Anonymous No.3214286]

holy shit I haven't been on /sci/ in like over a year and here is my fave tripfag still faggin the place up... it's like seeing an old friend that doesn't recognize me

[Colonel Coffee Mug !phJ7yIcs.Q No.3214290]

>>3214229

>mfw

>An interstellar spacecraft created by the Muuh from an icy object such as a comet. The maximum velocity of these ships rarely exceeds 1% of light speed; the slowest ships travel at a velocity only slightly above the escape velocity of the originating system. The Muuh have very slow metabolisms and long lifespans, so they can afford to wait while these slow craft travel between the stars. For fuel the ice ships use fusion of various kinds, or sometimes antimatter boosted fusion.

>Muuh antimatter creation is a very slow process, converting magnetic energy, geothermal power or wind power into antimatter in particle accelerators, the design of which has apparently not changed in millions of years.

>The motors are clustered together behind the ice object, which provides both fuel and propellant. These motors are angled to avoid the central tether, a very strong carbon nanotube thread plated with a metallic sheath to reduce erosion. Trailing some way behind the motors is a radiation shield, a hollow tungsten block filled with ice.

>At the far end of the tether is a Muuh habitat, a simple cylinder filled with ices, nutrients and accommodation for the Muuh crew, who spend most of the journey in a state of low activity.

[sage No.3214289]

saged for useless spam

[Colonel Coffee Mug !phJ7yIcs.Q No.3214294]

>>3214290

[Anonymous No.3214302]

>>3214286
>mfw he doesn't even acknowledge my post with a simple 'lol'/'cool story' or anything at all
>trulyforeveralone.jpg

[Anonymous No.3214303]

Is there a point in this thread?
I would sage but this is the closest to science in front page.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214306]

>>3214302
>>3214286

I'm not sure how to reply.

>it's like seeing an old friend that doesn't recognize me

Do you remember a post you made, see if I remember it? Maybe something quartz-related?

[Anonymous No.3214311]

What's the purpose of such a vessel? There probably aren't any worthwhile destinations within the ship's range. Well, I guess unobtanium at Alpha Centauri would make the whole trouble worthwhile.

In other words: scifi with interstellar travel (if it's not a selfsustaining generation ship) won't happen. It's just improbable fantasy.
High-maintenance high-performance vessels for longrange missions are bogus.

[Anonymous No.3214324]

>>3214311

Bitch please.

Interstellar journey's need not take all that long subjectively. Accelerate to relativistic speeds and you'll be there in a few months.

[Anonymous No.3214333]

This is an old idea. They wanted to do it with nuclear reactions as well. Basically a parachute catches the reaction and you plow through it, and the ship then becomes a unweildly peice of space trash, and is completely vulnerable to impact. There are no materials that can hold up against the unavoidable impacts, even the microscopic shower of particles. There is no way we can travel anywhere until we have the ability to protect the ship, the locomotion is not the issue. This force feild solution likely will never come, because magnetism alone will not work, it basically requires some antigravity or special fluid. If you look at the rate physics is finding solutions to these issues and compare it to the rate we are destroying earth your realize we are never going anywhere.

[Mad Scientist !!Q11PG81nz2n No.3214342]

>>3214333

And yet, mankind will rule the stars.

[Anonymous No.3214347]

>>3214324
>Implying that the crews travel time matters
>Implying there is any significant time dialation at 0.92c

[Anonymous No.3214360]

>>3214306
Nah I don't have anything but don't worry, all I wanted was an acknowledgement of my existence. Thankyou.

[Anonymous No.3214377]

>>3214342
I hate how retarded sci fi is and what it does to you nerds.

[Mad Scientist !!Q11PG81nz2n No.3214412]

>>3214377

What did it feel like when you lost your indomitable spirit of exploration and ceased to be human?

[Colonel Coffee Mug !phJ7yIcs.Q No.3214434]

>>3214347

>implying it doesn't
>implying not one-third of the time at rest.

[Anonymous No.3214494]

>>3214434
>Implying it does
>Implying close to two years=few months
>Implying implications

[Anonymous No.3214586]

>>3214412
space =/= sea

space exploration =/= James Cook sailing the ocean

[Mad Scientist !!Q11PG81nz2n No.3214623]

>>3214586

Not sure what you're talking about. You seem to have inferred that I hold a position which I do not.

[Anonymous No.3214727]

>>3214311
>What's the purpose of such a vessel?
To get all of our eggs out of one basket. What we do beyond that is to each his own.

[Anonymous No.3214794]

Such selfish ideas, why should we spend such a incomprehensible amount of energy, just that YOU can travel to another star?
A relatively cheap, fusion or even fission powered generation ship will be possible in just a few hundred years, and it needs no, even then, completely unrealistic facilities to produce weightable amounts of antimatter.

[Colonel Coffee Mug !phJ7yIcs.Q No.3214826]

>>3214794

Valkyrie is an experiment on the minimal energy required to accelerate a single person to the stars. It can be scaled up, though that's riskier than scaling it down to send a single probe.

[Colonel Coffee Mug !phJ7yIcs.Q No.3215107]

>>3214205

>Interstellar mass beam propulsion network first conceived in the late 20th and early 21st centuries C.E. Today there are more beamrider routes than wormholes in the galaxy as a whole.

>The Network uses arrays of mass beam projectors to magnetically accelerate self maneuvering "smart dust" micropellets to near light speed and direct them toward a vessel equipped with a powerful magnetic/plasma sail. The pellets vaporize upon impact with the magsail and transfer their momentum to the craft, accelerating it to a significant percentage of lightspeed. Once accelerated up to cruising speed, the beamrider coasts on a course that takes it past a series of stars, brown dwarves, and free-floating extra-solar planets. Additional mass beam booster stations are built on and around these objects. Using a combination of the galactic magnetic field, onboard fuel, and mass beams from the booster stations, the beamrider is able to curve its course in a great arc back to its starting point, which is now used as another booster station to send the vessel around the circuit once again.

>As the beamrider passes near each of the booster stations, additional cargo, passenger, and resupply pods are accelerated to match velocity with the ship or are dropped off to be decelerated into the target system. Although the energy required to accelerate/decelerate the pods is considerable, it is far less than that required to constantly boost and decelerate entire self- sufficient spacecraft intended to survive years-long journeys between the stars all by themselves. The Network makes a huge initial investment to boost the main vessel up to speed to take advantage of the much greater savings later.

[Colonel Coffee Mug !phJ7yIcs.Q No.3215113]

>The first section of what would eventually become the Beamrider Network was conceived shortly after the discovery of the brown dwarves Yin and Yang along a rough line between the Sol system and Ross 128 in 280 a.t. However, it was not until fifty years later that construction of the first launchers was begun by the Orbital Alliance in Cis-Lunar Space. The program suffered from lack of funds, since most investment at the time was going into the more financially lucrative Nova Terra Project involving the colonization of Tau Ceti.

>While this was going on, the Jovian League detected a brown dwarf, which it named Patala, between Sol and Struve 2398 (the brown dwarf had been discovered several years earlier by Cis-Lunar astronomer ai and named "Nyx" but the Jovian name stuck), and began constructing a launcher around Triton in 346 with the launch of the first construction module taking place some fifteen years later. It was intended that from Patala the circuit would be extended to Struve 2398 and from there the search would be made for further brown dwarves.

>The Mars Republic meanwhile was keeping its options open by supporting both projects. Martians were among the crew in both the Orbital Alliance and the Jovian League missions.

>In 412 a combined cyborg and ai Orbital Alliance team aboard the Karl Schroeder reached Yin, seventy-six years before the Tsiolkovsky reached Tau Ceti, and five years before the Jovian-Martian vessel Advance reached Patala. Twelve years later the first segment linking SolSys and Yin was completed by neumann ai and human crews in orbit around Yin, and the following year a construction module launched towards Yang, where it arrived in 476. In 529 the link between Yang and Ross 128 was completed. In the new solidarity between the CisLunar, Martian, and Jovian superpowers, several joint missions were planned along both routes. At this time the Nanodisaster began to sweep the Solar System.

[Colonel Coffee Mug !phJ7yIcs.Q No.3215119]

>Records on this point are sketchy, but one thing is certain: The crew and support staff of the Cis-Lunar mass-beam facility gathered their families and community together and used the beam projectors to launch themselves toward Yin and out of the Solar System.

>It was not until sometime later, after control of the Solar System had been regained and additional interstellar vessels launched, that contact was reestablished with the descendants of the erstwhile colonists and construction workers living around Yin, Yang, Ross 128, Patala, and Struve 2398. During their long isolation, they had managed to both extend their respective networks and maintain contact with each other, although no complete cycler route had yet been finished. Since it was considered too dangerous to cycle through SolSys, several other routes had been attempted, including a Procyon link, but many of these had faced hostile isolationist AI and the projects blocked.

>After centuries of being cut off from Sol, the inhabitants of the cycler systems represented a unique developing civilization that was eager to rejoin galactic society, while at the same time maintaining the unique culture and identity they had developed while living on their own. Perhaps more importantly, they desired to continue the great projects they had begun so long ago, but with the help of First Federation technology and ai to accelerate things. With the resources available to them through the new technologies, they set about the work with renewed vigor, sometimes on their own, sometimes with the help of idealistic First Federation ai and hu visionaries. The seeds of what would become the modern Beamrider Network and the Deeper Covenant were born.

>The modern Beamrider Network extends across approximately a third of explored space and passes near just over a hundred million stars, brown dwarves, and extra-solar planets. Nearly all of these systems are inhabited by members of the Deeper Covenant.

[Colonel Coffee Mug !phJ7yIcs.Q No.3215125]

>Modern beamriders are huge vessels, often extending across hundreds of kilometers of space. Most of the ships' great size is made up of superconducting cables spread out across space with habitat modules affixed near the center of the meshwork. Most ships rotate and individual modules are attached at points where the local gravity is at the desired level.

>Despite their impressive dimensions, beamriders are actually rather small by modern standards. Even the largest vessels rarely have a complement of passengers and crew larger than a few hundred people, most of them travelling in biostasis (It is common practice on most ships for passengers and crew to spend 1/3 of the trip awake. Random shuffling of stasis/waking schedules ensures that a traveler will meet at least some new people with each awakening. More than a few people can report that they met their mate or a great romance while travelling aboard a beamrider).

>In the past, beamriders employed a variety of shielding methods to protect themselves against radiation and interstellar debris. Shields were initially a combination of magnetic fields and ionization lasers. Also a plasma screen, consisting of a portion of the vaporized incoming mass stream that was allowed to 'slip thru' the magsail, was fired ahead of the ship and acted to vaporize any larger particles encountered. As a last resort the ship employed powerful radar to locate larger bodies and would then use a combination of magnetic 'tacking' and onboard thrusters to dodge the object in question. At a standard cruise speed of .3 c there was generally time to maneuver at least a little.

>In the modern era most beamriders use a combination of magnetic and plasma shields backed up by Emple-dokcetic shielding. A very few ships rely solely on Emple-dokcetic shields, but most crews reject the idea of depending on but a single method to protect themselves and their passengers.

[Colonel Coffee Mug !phJ7yIcs.Q No.3215127]

>Standard cruising speed for a modern beamrider is .5c although smaller, faster 'hot beam' vessels can achieve speeds as high as .9c.

>Throughout most of the history of mindkind the Beamrider Network has provided a constant, if unobtrusive method of travelling between the stars. Although the development of conversion drive, reactionless drives, and wormholes has diverted some traffic from the Network, the majority of systems in the Nexus still make some use of it, if only for recreational purposes. For the majority of isolated solar systems, the Beamrider Network is their main link with the rest of galactic civilization, while the citizens of the Deeper Covenant and some non-militant Backgrounder cultures still make use of it almost exclusively.

[Anonymous No.3215132]

isn't achieving anything past 0.5 c impossible to achieve with even the ideal reactive drive that carries its own fuel? And that's provided you don't care about slowing down again

[Colonel Coffee Mug !phJ7yIcs.Q No.3215137]

>>3215132

A solution is to keep the fuel at home and beam it. See my posts above: A magnetic sail pushed by a stream of relativistic plasma.

[Anonymous No.3215167]

>>3215132
Wait a sec... where on earth does this 0.5c limit come from?

To take an extreme example, consider an atom in the LHC (a gold ion or something) which you accelerate to 99.999%+ the speed of light. If we make an opening in the beampipe and let the atom be shot off into space, we've made a "spaceship" that travels at 99.999%+ the speed of light (where the entire LHC is the reaction mass, essentially).

[Anonymous No.3215182]

>>3214251
>Jim Powell and I have a system that can perform both services (particle shielding and heat shedding), at least during the acceleration and coast phases of flight. We can dump intercepted engine heat into a fluid (chiefly organic material with metallic inclusions) and throw streams of hot droplets out ahead of the ship.
The droplets radiate their heat load into space before the ship accelerates into and recaptures them in magnetic funnels for eventual reuse.
How would this work for a cruising ship? If you launch the fluid out in front of you, faster than you, you aren't going to get it back.

[Anonymous No.3215203]

What happens if anti-hydrogen collides with, say, oxygen anyway? Does it become nitrogen?

[Colonel Coffee Mug !phJ7yIcs.Q No.3215206]

>>3215167

Yes, but again, the force imparted on the protons is external. A ship has to carry its own fuel.

>>3215182

During acceleration it would just fall back to you. While cruising, they talk about magnetic fields used to retrieve it.

Though there may not even be a cruising phase: A Brachistochrone orbit could be attempted by accelerating to the interstellar midpoint, turning around, and beginning deceleration.

[Anonymous No.3215310]

>>3215206
Sounds like an unnecessary usage of energy, given there are alternatives. I'd assume that any craft with a set destination could probably calculate a way of ensuring speed is constantly changing, so as you say, it could probably be avoided entirely.
Thanks for replying

[Anonymous No.3215321]

>>3215167
Bitches don't know 'bout my equation.

[Anonymous No.3215375]

>>3215167
problem solved! build a large particle accelerator around the earth and shoot spaceships to the stars!

[Colonel Coffee Mug !phJ7yIcs.Q No.3215378]

>>3215375

http://www.iase.cc/launcher.htm