Colonized Interstellar Vessel: Conceptual Master Planning

Tom Kalbfus · 2014-06-02 06:01:39

http://www.icarusinterstellar.org/colon … -planning/

posted by Steve Summerford on September 10, 2012

(redacted version: full paper available here: http://www.steve-summerford.com/Coloniz … Vessel.pdf )

INTENT

The notion of humanity exploring distant worlds has long been the substance of dreams; from early Renaissance thinkers condemned for their heretical visions, to banal fodder for modern day science fiction plots. With humanity’s insatiable appetite for knowledge and discovery, coupled with concerns surrounding the potential for an earthly cataclysmal event, it is only natural that armed with enough curiosity, we should seek to explore new horizons. As such, design proposals contained within this document aim to outline a smaller Colonized Interstellar Vessel (CIV), examining guidelines necessary to provide adequate living conditions for a given population, rather than envisioning how to encapsulate an exact visage of earth.

As a great deal of contemporary focus is commonly directed toward the technological requirements of space travel, designers of a CIV will need to be mindful that equal attention is allocated to the preservation of the mental and emotional human element. Without proper planning and thoughtful consideration to the physical, spatial, and psychological needs of the people tasked with living and operating in such a colony, even the most advanced technological achievements may risk failing at the human level. Design for the psyche and associated pragmatic daily functions should be of equal concern as those of cosmic radiation shielding, fuel supply, food procreation, etc. Should the precious human component be allowed to atrophy, the complete interstellar mission risks failure.

Thoughtful consideration must be exercised throughout the design phases to ensure a harmonious interconnection between infrastructure and its end users. Architecture and the interstitial spaces it creates should aim to promote healthy community living, while also meeting the basic territorial and privacy needs that human nature has become accustomed to on earth. Some methods for promoting psychological and physical well being through environmental design include:
• Allowing the user to modify the configuration and visual appearance of a space,
• Creating long vistas and distant focal points – Using structure to choreograph space, allowing for discovery and ‘unfolding’
• Varying materials, forms, shapes, textures, and colors to engage the mind
• Maintaining some semblance or connectivity to nature

The human brain will always be among the most advanced technologies aboard such a vessel; as such, the world designed around it should nurture and inspire, rather than simply function as containment.

DESIGN CONSIDERATIONS

The proceeding content derives and builds upon information contained within the Stanford Torus study of 1975, titled “NASA Document SP-413”.

While many geometries have been explored for vessel formation, the most popular include the sphere, cylinder, torus, and banded toruses; and previous studies have concluded that both the sphere and cylinder were less efficient compared to the torus configurations with regard to spatial usability.

Rather than developing the predominant projected living plane throughout the toruses in a banded fashion, a simple 90-degree reversal of thinking results in a different geometry resembling ‘banded cylinders’ running parallel to the axis of rotation. Reducing the cost and developmental restrictions of curved planes, the primary living spaces are designed to have flat bottoms and faceted extrusions, extending into long linear structures, referred to as ‘bays’. This makes it possible to provide sufficient colonial living space while maintaining a compact vessel design that should allow for more feasible propulsion and life support systems engineering.

Such a configuration of interconnected bays rotating about a central axial zero-g hub, with each bay containing dwellings, agriculture facilities, civic structures, open spaces, and places of work and research, will be the basis of design moving forward.

In an effort to design for maximum vessel modifiability, modularity and program become intimately engaged. For any early concept to have any sustainable longevity, it must be able to adapt to a constantly evolving set of parameters — both technical and programmatic — that demand reactive scalability. Establishing a clear module that can easily be replicated, accommodate scale flux, and provide for an efficient use of space becomes a key nodal component. A whole composed of many modifiable parts lends well to an organic evolution of design.

Composed of many modules, each of the vessel’s bays should vary in architectural character and functional layout. Interconnected by a series of semi-circular bridges (pedestrian viaducts), one could meander indefinitely throughout the entire colony, covering several kilometers (km). The proposed bay consists of 5 initial modules, creating a bay nearly 775m in length.

HABITAT CHARACTERISTICS FOR CONSIDERATION:

– It is important that the colonists have the ability to modify their dwellings and neighborhoods from time to time, necessitating the development of several different, but dimensionally related, prototypical homes that can be reconfigured periodically while still functioning as healthy neighborhoods.

- Creating numerous bays within the colony, rather than one enormous open space, permits a greater degree of control in the event of a significant adverse event (such as a medical emergency, agricultural disease outbreak, or mechanical systems / hull failure).

- Each residential module should attempt to be uniquely laid out, staggered, and utilized as a means for controlling and creating long and short vistas. Moving throughout a residential neighborhood should be a mentally enriching experience, thoughtfully choreographed, and not quickly absorbed and discarded by the brain — as would be the case if looking down a long corridor of homes.

– Multipurpose vegetation should be utilized throughout the community. In order to maximize efficiency, plant species should be used that provide edible parts or otherwise somehow contribute to the food or medicinal supply.

- Preserving pedestrian corridors and open space between structures provides colonists with the opportunity to gather and engage in social or recreational activities and increases the perceived openness, ultimately enhancing mental health and well being.

- Although life will be relegated to existing within an artificially created environment, it should not always feel as such. While wood and stone may not be conducive to spacecraft design, the tactile nature of such elements improves the quality of a space by creating a semblance of nature connectivity.

As momentum behind pursuing such a monumental design challenge increases over time, it will be the cumulative effect of all the predecessor dreaming and design work that will ultimately allow such a marvel to be constructed. It may take decades, centuries, or even longer to fully realize, but all of humankind’s immense engineering design ideas began somewhere.

Tom Kalbfus · 2014-06-02 11:18:53

What do you think of this? Also read the full PDF version to which a link has been provided. There are a lot of applications to this CIV that could also be applied to Mars colonization. For one thing the CIV would also make a wonderful cycling spaceship. For the purposes of going to Mars, a fission reactor would suffice. It could also transport 10,000 colonists to Mars in a single trip, and similar modules could be places or built on the surface of Mars for human habitation. As an interplanetary vessel, it could reach any destination in the Solar System in luxury liner comfort. Also the 8 modules could be constructed on Earth and used to simulate the living conditions on an interstellar ark. Just imagine these modules placed in Antarctica to support a population of 10,000 in shirt sleeve comfort with a nuclear reactor powering the whole thing and artificial sunlight provided to the community during the long Polar night.

Last edited by Tom Kalbfus (2014-06-02 11:19:25)

Excelsior · 2014-06-02 20:12:29

There's a lot to go through there.

My first concern would be the impact mitigation strategy, which seems to be to make as small a a target as possible and pray, instead of assuming an impact is going to happen and building accordingly. The latter will cost you in propulsion from the outset, but you could could make up for it in aerobraking at your destination.

I don't think they addressed propulsion at all, but hopefully we are starting out at least 25% light speed, otherwise we won't be going very far before no one who leaves reaches their destination, which only compounds an already delicate social experiment. Unmanned precursors to these systems are essential, so people have a clear idea of what is ahead of them, but even so, a generation or more into the trip and the cause for leaving would lose its meaning for the youth tasked with building a civilization from scratch.

Tom Kalbfus · 2014-06-03 05:38:52

What if we simply deployed a solar sail some distance ahead of the CIV? A micro meteor that hits it at 3.125 of the speed of light gets turned to plasma by the impact, the plasma is then deflected by the CIV's magnetic field when it reaches the ship. The CIV spends most of its time coasting rather than accelerating, so I imagine deploying a solar sail ahead of the starship and simply letting it hang there would not be too difficult. Since the Solar Sail will be huge in comparison to the starship, it would cover most of the dangerous approach vectors a meteor could possibly take. Lets say the solar sail is a disk 100 km wide and is positioned 3,000 km ahead of the starship. About 1 third of a second would transpire between when a meteor hits the solar sail, giving the impact plasma time to disperse before it hits the magnetic field. A meteor would be moving relative to the ship at around 9,375 km/sec. If the object is also moving 10 km/sec sideways relative to the direction of travel it will not reach the starship before it is past it, the most likely path I one where it hits the solar sail first and the energy of impact will destroy it before it reaches the CIV. That is what I would do.

I think 25% of the speed of light is a bit extreme and puts it beyond the ability of a fusion drive to reach, though perhaps a form of beamed propulsion could reach this velocity, but that would also likely put the launch date beyond the end of the 21st century. The whole idea of a generation starship is to exchange time for speed, it is likely that we'll have some sort of fusion drive by 2100 AD, having a giant laser is a bit less likely I think. The picture shows the bottom stage of a Daedalus Space Probe, if that is the case the cruise velocity would be around 3.125% of the speed of light, since that is one quarter of the 12.5% velocity that a 2-stage Daedalus Probe is capable of reaching, so we sacrifice velocity to maximize payload. I figure what's the hurry. chances are once the colonists reach Alpha Centauri, they will continue to live onboard the CIV anyway, as no planet would be capable of supporting human life, what they could so is mine asteroids and build more O'Neill colonies to support their expanding population. The journey would take 140.8 years at a velocity of 3.125% of the speed of light. One advantage is resupply ships can visit them at 40 years into their journey an 80 years into the journey. the Daedalus bottom stage can reach 6.25% of the speed of light and then the upper stage can slow down to 3.125% of the speed of light matching the CIV's velocity with a total delta-v of 9.375% of light speed, less than the 12.5% light speed delta-v the original Daedalus space probe was designed for. Less fuel spend means more payload deliverable to the CIV, their are two opportunities in mid-flight for the CIV to receive resupply from Earth. After reaching the Alpha Centauri system a more massive resupply vessel can reach them 20 years after they arrived traveling at the speed of 3.125% of the speed of light just like the colony.

Last edited by Tom Kalbfus (2014-06-03 05:39:34)

Tom Kalbfus · 2014-06-03 09:03:28

Another defensive layer is to inflate a low pressure balloon filled with hydrogen around the CIV, place the magnetic coil around the perimeter of the balloon to generate the magnetic field around it. The hydrogen within the balloon is extremely low pressure, just enough to make the balloon spherical within the vacuum of space. So if a micrometeor somehow misses the solar sail placed in front of the starship's path, it will hit the membrane of the hydrogen balloon that completely surrounds the starship, and by the way any holes punched through the balloon will be slow to leak out the hydrogen since this balloon will be low pressure, so low pressure that it will hardly slow down the rotation of the CIV for gravity.

JoshNH4H · 2014-06-03 11:36:25

Tom-

Good idea with the solar sail. The question to me is how much of an effect it will have when it comes to pushing a particle off course. At 3% the speed of light, a 0.1 milligram particle would impact with the same energy as 1 kg of TNT. If it had a density of 1000 kg/m^3, it would have a cross-sectional area of 2.6e-7 m^2. Current solar sails have masses in the region of .005 kg/m^2, which means that it would intercept 1.3e-9 kg of solar sail material. On impact, this would release 53,000 J of energy, more than enough to vaporize the particle.

Unfortunately, this is not enough. It will take this plasma just .33 s to travel between the sail and the ship, and it won't have spread out enough by then to not do damage. To be fair, I haven't done any calculations on the matter and .33 s is a long time in some contexts. Also being fair, a kilo of TNT is a whole lot, even spread out over an area. If the solar sail is inclined somewhat that would probably be a better solution, because it would push the material away from the ship and probably cause it to miss.

Either way, I really like the separated cylinder idea. However, I wonder if a rotating rectangular prism might not be better. Living quarters could be near the outer ring, and work/habitation spaces all the way up to whatever a healthy g level is. Above this could be storage and machinery which does not need to be accessed on a regular basis.

Excelsior · 2014-06-03 12:42:07

In terms of a time table, I don't think manned interstellar travel is going to happen this century anyway. We have plenty to do right in our own system. Interstellar exploration first requires massive telescopes to get a good idea of where to aim, and then a substantial unmanned probe with a rather sophisticated AI to properly survey the system, so potential colonists know what they are getting themselves into, before sending people. An interesting twist could be building or adding the intermediate step of an AI control seeder colony, that gets a head start on the ISRU, either for further long term AI exploration, or as a precursor to settlement. Among all the things to do here through the end of the century, the telescopes are certainly feasible, and we could even be ready to launch such probes, and are more than worthy objectives, but we have to keep in mind that it could take the better part of a century just to get results back. Which is why speed is so important. We have a hard enough time rebuilding capability when one generation retires, how much worse would it be if all the people responsible for the design and launch, and their children, where dead of natural causes, before data started to flow back. It would make the current efforts with the ICEE-3 mission look trivial be comparison. If interstellar drives can't propel an unmanned probe to 1/3 light speed, and a cluster of such boosters can't propel a manned vessel to 1/4 light speed, our time is probably better spent improving our drives. We don't want to get a whole generation of people all jazzed up to be the first humans to step foot on an exoplanet, only to have a settlement waiting to greet them.

In terms of shielding, we need to be thinking in terms of sloped armor, the bulk of which would be on the bow of course, but the flanks can't be ignored either. A solar sail can either be propulsion or shielding, but not both. Our best bet for propulsion is some Project Orion or Daedalus derivative. If fusion can't do it, perhaps anti-matter can.

It's going to many centuries before we expend our ability to simply build more orbital habitats right in our own system. Barring tyrannical oppression, a system wide comic disaster, or natural curiosity and ambition, there would be little need to leave. Unless there is at least a marginally habitable world at the other end, or some other equally lucrative goody uncovered by AI's, I'm not sure why people would go. Use the wastes for AI seeder colonies, and send the people to the habitable systems.

Tom Kalbfus · 2014-06-03 14:09:43

JoshNH4H wrote:

Tom-
Good idea with the solar sail. The question to me is how much of an effect it will have when it comes to pushing a particle off course. At 3% the speed of light, a 0.1 milligram particle would impact with the same energy as 1 kg of TNT. If it had a density of 1000 kg/m^3, it would have a cross-sectional area of 2.6e-7 m^2. Current solar sails have masses in the region of .005 kg/m^2, which means that it would intercept 1.3e-9 kg of solar sail material. On impact, this would release 53,000 J of energy, more than enough to vaporize the particle.
Unfortunately, this is not enough. It will take this plasma just .33 s to travel between the sail and the ship, and it won't have spread out enough by then to not do damage. To be fair, I haven't done any calculations on the matter and .33 s is a long time in some contexts. Also being fair, a kilo of TNT is a whole lot, even spread out over an area. If the solar sail is inclined somewhat that would probably be a better solution, because it would push the material away from the ship and probably cause it to miss.
Either way, I really like the separated cylinder idea. However, I wonder if a rotating rectangular prism might not be better. Living quarters could be near the outer ring, and work/habitation spaces all the way up to whatever a healthy g level is. Above this could be storage and machinery which does not need to be accessed on a regular basis.

The collision with the sail heats the particle up to a plasma, as a plasma it is then subject to magnetic fields, that is the idea, instead of a neutral particle traveling through the magnetic field, a plasma would be deflected by the field, that is the thing about magnetic fields, it only affects charged particles. As a final stopgap, I would enclose the starship within a low pressure hydrogen balloon 2 km in diameter. A particle would hit the surface of the balloon and be vaporized, the hole in the balloon could later be patched by robots. Hopefully most of the meteors are intercepted by the sail an magnetic field.

Tom Kalbfus · 2014-06-03 14:23:40

Excelsior wrote:

In terms of a time table, I don't think manned interstellar travel is going to happen this century anyway. We have plenty to do right in our own system. Interstellar exploration first requires massive telescopes to get a good idea of where to aim, and then a substantial unmanned probe with a rather sophisticated AI to properly survey the system, so potential colonists know what they are getting themselves into, before sending people. An interesting twist could be building or adding the intermediate step of an AI control seeder colony, that gets a head start on the ISRU, either for further long term AI exploration, or as a precursor to settlement. Among all the things to do here through the end of the century, the telescopes are certainly feasible, and we could even be ready to launch such probes, and are more than worthy objectives, but we have to keep in mind that it could take the better part of a century just to get results back. Which is why speed is so important. We have a hard enough time rebuilding capability when one generation retires, how much worse would it be if all the people responsible for the design and launch, and their children, where dead of natural causes, before data started to flow back. It would make the current efforts with the ICEE-3 mission look trivial be comparison. If interstellar drives can't propel an unmanned probe to 1/3 light speed, and a cluster of such boosters can't propel a manned vessel to 1/4 light speed, our time is probably better spent improving our drives. We don't want to get a whole generation of people all jazzed up to be the first humans to step foot on an exoplanet, only to have a settlement waiting to greet them.

There is no reason why we couldn't do both. launch the slow generation ship as soon as we can, and afterwards develop a better and faster drive system. One thing to keep in mind is that it doesn't really matter what's in the Alpha Centauri System so long as its something we can build additional space colonies out of, we'll start with a 10,000 person work force and they'll already be in space, the presence or absence of Earthlike planets in te system would be immaterial to their continued survival so long as all the elements needed to survive are in system and accessible to them. The Prime real estate would be Alpha Centauri A, the CIV could be adapted to receive the sunlight of that star once it arrives, and the fusion reactor won't be needed anymore. The people that arrive in system can find many interesting things, but their main purpose is to build a colony and survive.

Excelsior wrote:

In terms of shielding, we need to be thinking in terms of sloped armor, the bulk of which would be on the bow of course, but the flanks can't be ignored either. A solar sail can either be propulsion or shielding, but not both. Our best bet for propulsion is some Project Orion or Daedalus derivative. If fusion can't do it, perhaps anti-matter can.
It's going to many centuries before we expend our ability to simply build more orbital habitats right in our own system. Barring tyrannical oppression, a system wide comic disaster, or natural curiosity and ambition, there would be little need to leave. Unless there is at least a marginally habitable world at the other end, or some other equally lucrative goody uncovered by AI's, I'm not sure why people would go. Use the wastes for AI seeder colonies, and send the people to the habitable systems.

An artificial world in the habitable zone of Alpha Centauri A could be built their if nothing else. An Earthlike planet would be helpful as an object of study and could be used as incentive to fund the project in exchange for a return of data. Probably most of the Worlds in the Alpha Centauri system will be rock balls rather than gas giants or balls of ice, the proximity of the two stars to each other rules out significant objects in the outer star system.

Anyway its best to think of it as an in interstellar colony, the colony is the starship, the destination system only provides additional material to build stuff out of and an energy source in the form of a star or stars.

JoshNH4H · 2014-06-03 15:43:25

Tom Kalbfus wrote:

The collision with the sail heats the particle up to a plasma, as a plasma it is then subject to magnetic fields, that is the idea, instead of a neutral particle traveling through the magnetic field, a plasma would be deflected by the field, that is the thing about magnetic fields, it only affects charged particles. As a final stopgap, I would enclose the starship within a low pressure hydrogen balloon 2 km in diameter. A particle would hit the surface of the balloon and be vaporized, the hole in the balloon could later be patched by robots. Hopefully most of the meteors are intercepted by the sail an magnetic field.

Ah. Do you have any estimate regarding how much power/mass it would take to generate the requisite magnetic fields?

Let's say you have a solar sail canted at a 45 degree angle, shaped like a mountain with its peak at the center of area of the ship. Your 1 kg of TNT, 1e-7 kg particle strikes the sail head on, and because of the angle will hit 1.4 times as much material as it would with an un-canted sail. This is 1.8e-9 kg. Let's say the mass of the sail and an equal mass of the impinging particle convert 20% of the energy released on impact to particles travelling perpendicularly inward from the sail. By reaction, the micrometeoroid will be travelling 674 km/s radially away. This means that it will certainly miss the ship, very good news.

Tom Kalbfus · 2014-06-03 20:03:54

JoshNH4H wrote:

Tom Kalbfus wrote:
The collision with the sail heats the particle up to a plasma, as a plasma it is then subject to magnetic fields, that is the idea, instead of a neutral particle traveling through the magnetic field, a plasma would be deflected by the field, that is the thing about magnetic fields, it only affects charged particles. As a final stopgap, I would enclose the starship within a low pressure hydrogen balloon 2 km in diameter. A particle would hit the surface of the balloon and be vaporized, the hole in the balloon could later be patched by robots. Hopefully most of the meteors are intercepted by the sail an magnetic field.
Ah. Do you have any estimate regarding how much power/mass it would take to generate the requisite magnetic fields?

Actually no, something I need to look up when I have the time, I heard about magsails however, Bob Forward proposed them, with loops of superconducting material, and interstellar space is very cold, should be quite easy to keep material at superconducting temperatures out there. Past a certain point magsails could be used to slow the ship down upon reaching the destination, I'm sure Alpha Centauri A or B has significant amounts of stellar wind, if that is the case then we can devote more of the payload to habitable area instead of fuel to slow the ship down. A precursor probe would be just the thing to measure the stellar wind of the Alpha Centauri system, with the same technology that propels the CIV, a one way fly through probe can reach 12.5% of the speed of light and get there in 35.2 years, better yet, why not equip it with its own magsail and have it attempt to brake with the Stellar winds, if it succeeds in stopping all the way, that means potentially the CIV could travel at 12.5% of the speed of light and b their in 35.2 years, it would need a two stage Daedalus type rocket scaled to carry the extra payload of the CIV, so it would be much larger than the Daedalus probe, it would still be a one-way journey, the colonists would have to find their own resources in-system in which to survive, but that is kind of the point of colonization, and similar cargo ships can also be send from the Solar System to resupply the colony at regular intervals, including some with additional colonists possibly. If one stage is used, then its a 70.4 year journey.

JoshNH4H wrote:

Let's say you have a solar sail canted at a 45 degree angle, shaped like a mountain with its peak at the center of area of the ship. Your 1 kg of TNT, 1e-7 kg particle strikes the sail head on, and because of the angle will hit 1.4 times as much material as it would with an un-canted sail. This is 1.8e-9 kg. Let's say the mass of the sail and an equal mass of the impinging particle convert 20% of the energy released on impact to particles travelling perpendicularly inward from the sail. By reaction, the micrometeoroid will be travelling 674 km/s radially away. This means that it will certainly miss the ship, very good news.

Yeah could work, the faster the velocity though the tougher the meteoroid problem will be. And of course interplanetary versions of this starship could be used to ferry 10,000 colonists to Mars at a time with drives that run on atomic fission or even solar power.

Tom Kalbfus · 2014-06-04 17:41:46

One alternative to Daedalus would be to use thermonuclear bombs to propel the CIV
http://en.wikipedia.org/wiki/Project_Or … ropulsion)

Interstellar missions[edit]
Freeman Dyson performed the first analysis of what kinds of Orion missions were possible to reach Alpha Centauri, the nearest star system to the Sun.[12] His 1968 paper "Interstellar Transport"[13] (Physics Today, October 1968, p. 41–45) retained the concept of large nuclear explosions but Dyson moved away from the use of fission bombs and considered the use of one megaton deuterium fusion explosions instead. His conclusions were simple: the debris velocity of fusion explosions was probably in the 3000–30,000 km/s range and the reflecting geometry of Orion's hemispherical pusher plate would reduce that range to 750–15,000 km/s.[14]
To estimate the upper and lower limits of what could be done using contemporary technology (in 1968), Dyson considered two starship designs. The more conservative energy limited pusher plate design simply had to absorb all the thermal energy of each impinging explosion (4×1015 joules, half of which would be absorbed by the pusher plate) without melting. Dyson estimated that if the exposed surface consisted of copper with a thickness of 1 mm, then the diameter and mass of the hemispherical pusher plate would have to be 20 kilometers and 5 million metric tons, respectively. 100 seconds would be required to allow the copper to radiatively cool before the next explosion. It would then take on the order of 1000 years for the energy-limited heat sink Orion design to reach Alpha Centauri.
In order to improve on this performance while reducing size and cost, Dyson also considered an alternative momentum limited pusher plate design where an ablation coating of the exposed surface is substituted to get rid of the excess heat. The limitation is then set by the capacity of shock absorbers to transfer momentum from the impulsively accelerated pusher plate to the smoothly accelerated vehicle. Dyson calculated that the properties of available materials limited the velocity transferred by each explosion to ~30 meters per second independent of the size and nature of the explosion. If the vehicle is to be accelerated at 1 Earth gravity (9.81 m/s2) with this velocity transfer, then the pulse rate is one explosion every three seconds.[15] The dimensions and performance of Dyson's vehicles are given in the table below

----------------------------------------"Energy Limited"--------------------------"Momentum Limited"
---------------------------------------- Orion------------------------------------------------------ Orion

Ship diameter (meters)-------------- 20,000 m ------------------------------------------------- 100 m

Mass of empty ship (metric tons) --- 10,000,000 t (incl.5,000,000 t copper hemisphere) --- 100,000 t (incl. 50,000 t structure+payload)

+Number of bombs = total bomb mass (each 1 Mt bomb weighs 1 metric ton)
----------------------------------------- 30,000,000 ----------------------------------------------- 300,000

=Departure mass (metric tons) ----- 40,000,000 t ---------------------------------------------- 400,000 t

Maximum velocity (kilometers per second)
----------------------------------------- 1000 km/s (=0.33% of the speed of light) ------------- 10,000 km/s (=3.3% of the speed of light)

Mean acceleration (Earth gravities) -- 0.00003 g (accelerate for 100 years) ------------------- 1 g (accelerate for 10 days)

Time to Alpha Centauri (one way, no slow down)
------------------------------------------ 1330 years ----------------------------------------- 133 years

Estimated cost
------------------------------------------ 1 year of U.S. GNP (1968), $3.67 Trillion --------------- 0.1 year of U.S. GNP $0.367 Trillion

Later studies indicate that the top cruise velocity that can theoretically be achieved by a Teller-Ulam thermonuclear unit powered Orion starship, assuming no fuel is saved for slowing back down, is about 8% to 10% of the speed of light (0.08-0.1c).[2] An atomic (fission) Orion can achieve perhaps 3%-5% of the speed of light. A nuclear pulse drive starship powered by Fusion-antimatter catalyzed nuclear pulse propulsion units would be similarly in the 10% range and pure Matter-antimatter annihilation rockets would be theoretically capable of obtaining a velocity between 50% to 80% of the speed of light. In each case saving fuel for slowing down halves the max. speed. The concept of using a magnetic sail to decelerate the spacecraft as it approaches its destination has been discussed as an alternative to using propellant, this would allow the ship to travel near the maximum theoretical velocity.[16]
At 0.1c, Orion thermonuclear starships would require a flight time of at least 44 years to reach Alpha Centauri, not counting time needed to reach that speed (about 36 days at constant acceleration of 1g or 9.8 m/s2). At 0.1c, an Orion starship would require 100 years to travel 10 light years. The astronomer Carl Sagan suggested that this would be an excellent use for current stockpiles of nuclear weapons.[17]
Further information: Interstellar travel

Probably were looking at a 1300 year mission with slow down, or perhaps 666 years if a magsail could be used to slow down. A larger version of the CIV would probably be called for one propelled by nuclear bombs, something on the order of 80 km in diameter with all the proportions increased 100 times, a full potential population of 100 million, but over a millennial voyage, it would probably be a good idea to start with a smaller population of perhaps 80,000, not going to happen this century except with massive robotics, it is still a smaller project than terraforming Mars.

Last edited by Tom Kalbfus (2014-06-04 17:54:54)

Void · 2014-06-05 08:18:43

Hope you won't mind the intrusion.
I have arrived at a question I cannot answer for myself by viewing your discussion.

Can a hybrid be of any value where:
A solar sail of massive proportions first propells the starship, but the starship also has an on borard Orion propulsion device?

Further defined:

First the solar boost would happen with or without laser assist from the inner solar system.

If with lasers, then they would only be used for an initial fraction of the mission, which would elimate the problems of propelling a starship and braking it's speed solely with laser propulsion.

When that was over a period of crusing would occur where the solar sail was collected an refabricated into other parts for use in the starship perhaps contibutin to the fabrication of the collision shield you have been discussing.

Then the Orion phase of propulsion would occur until speed was maximum cruse speed was reached.

During cruse, the starship would be reconfigured with on board materials to do magnetic braking.

I don't know if it would be possible but it would be ideal if the momentum of the ship could be converted into the electricity to create the magnetic field. (Induction)

JoshNH4H · 2014-06-05 08:45:01

Because solar sails are low acceleration, while Orion drives are high acceleration, it typically does not make sense to compound the two. At least not in my opinion, I've been wrong before

Void · 2014-06-05 10:13:17

I will reply back that the dawn probe used/uses two different types of propulsion.
To leave the Earth gravity well Chemical. To navigate the suns gravity well electric.
http://dawn.jpl.nasa.gov/
The character is inverted though. High short term thrust first then low sustained thrust.

If a solar sail takes the payload out to the reasonable limits of the provision of photon thrust, and then the mass of the sail is reused that is a plus. Then the Orion kicks in, and can either be of less mass, or be able to accelerate the payload to a higher speed, because it starts out higher in the suns gravity well where the gravitation pull is less, and may be already moving at a significant speed.

Last edited by Void (2014-06-05 10:29:13)

Tom Kalbfus · 2014-06-05 10:23:11

JoshNH4H wrote:

Because solar sails are low acceleration, while Orion drives are high acceleration, it typically does not make sense to compound the two. At least not in my opinion, I've been wrong before

Just because they can accelerate at 1 g doesn't mean it they should. Where does accelerating at 1 g for 10 days get us? Its still going to coast for over a century, might as well take that acceleration more slowly with a giant generation ship that spins for gravity. And plus I don't see the point of sending a ship on a one way fly through mission if its going t take 1000 years to get there. One-way fly throughs have to get their quickly to send back the data otherwise there is no point, for a generation ship, a slowdown is assumed since the mission is for those onboard and not for those who sent it.

Last edited by Tom Kalbfus (2014-06-05 10:23:46)

Tom Kalbfus · 2014-06-05 10:27:15

Void wrote:

Hope you won't mind the intrusion.
I have arrived at a question I cannot answer for myself by viewing your discussion.
Can a hybrid be of any value where:
A solar sail of massive proportions first propells the starship, but the starship also has an on borard Orion propulsion device?
Further defined:
First the solar boost would happen with or without laser assist from the inner solar system.
If with lasers, then they would only be used for an initial fraction of the mission, which would elimate the problems of propelling a starship and braking it's speed solely with laser propulsion.
When that was over a period of crusing would occur where the solar sail was collected an refabricated into other parts for use in the starship perhaps contibutin to the fabrication of the collision shield you have been discussing.
Then the Orion phase of propulsion would occur until speed was maximum cruse speed was reached.
During cruse, the starship would be reconfigured with on board materials to do magnetic braking.
I don't know if it would be possible but it would be ideal if the momentum of the ship could be converted into the electricity to create the magnetic field. (Induction)

The Orion Pusher plate would make a great erosion shield if you turn the ship around and place I forward, if its good at blocking atomic explosions it should serve to block cosmic rays just fine until its needed to slow down again, in which case it will be in that position anyway. The amount of time spend accelerating is a small portion of the total trip time anyway, unless a giant laser is being employed to continuously accelerate it for half the journey.

Void · 2014-06-05 16:00:23

Interesting topic Tom.

Void · 2014-06-05 19:44:50

Reusing components is a good idea.

Tom Kalbfus · 2014-06-05 20:10:00

Thanks. An Orion type propulsion system would bring it down to our tech level since we know how to make hydrogen bombs, I'm not sure what the minimum size for a starship propelled by Fusion bombs would be, I suspect such a starship would be huge, each bomb would need a fission trigger that uses plutonium, to get the best use out of a limited supply of Plutonium you probably want to use high yield fusion bombs, the Tsar bomb is an example of a 100 megaton fusion bomb. http://en.wikipedia.org/wiki/Tsar_Bomba
With 100 megaton Tsar bombs, each one weighing 100 tons, we could propel a starship with an empty mass of 1,000,000,000 tons I believe this is 1/50th the mass of an O'Neill Colony, to propel an O'Neill Colony with the energy limited design, we would need 1.5 billion Tsar bombs each one weighing 100 tons, so 150 billion tons of Tsar Bombs to propel a 50 billion ton O'Neill cylinder. An O'Neill Cylinder is 20 miles by 4 miles or 32 km by 6.4 km. Each Cylinder is rated to hold 20 million passengers.

JoshNH4H · 2014-06-06 11:21:12

Void-

While that spacecraft did use two different propulsion systems, it used them for two different purposes. The big delta-V maneuvers were handled by high-thrust chemical propulsion, which also benefited from a boost (the Oberth effect) that would not have been present for low-thrust ion propulsion. Meanwhile, the ion drive was used to perform low delta-V, high precision long term firings of circularization. Your proposal was to hybridize high thrust and low thrust propulsion for the same purpose, increasing speed. Assuming a constant area sail starting at 30,000,000 km from the Sun (.2 AU, about half the distance from the Sun to Mercury) and continue sailing to infinity, and assume that the ship is 50% sail by mass, with a sail at 5 g/m^2 so a total mass of 10 g/m^2. At infinity, the craft will be moving a bit more than 30 km/s. I ignored the Sun's gravitational field in this calculation, but the fact that it's relevant just goes to show that Solar sails will not be useful for building up significant speeds.

Interestingly, in the above case the effective exhaust velocity for the solar sail was 4300, significantly lower than any Orion drive. If the population is 10,000 people, and you need 25 tonnes of ship "stuff" per person (a lowball estimate, IMO) the ship will mass 250,000 tonnes. This will require 5e11 m^2 of sail area, which corresponds to an area equivalent to the cross section of the dwarf planet Ceres. In Terran terms, that's the area of Spain or Texas.

Solar sails have their uses, but going fast is not one of them.

Orion, on the other hand, is a great propulsion method.

Void · 2014-06-06 11:54:53

Hi Josh, here we go again!

http://www.space.com/22442-solar-sail-s … craft.html

An extremely lightweight 62-mile-wide (100 kilometers) sail unfurled close to the sun could make an interstellar voyage in 1,000 years

So that you don't misunderstand, I value you input, even if it can be emotionally annoying occasionallly.

Of course they may be claiming 1000 years by adding push with lasers or microwaves.

Or you may correct me again.

Anyway, I want to segway, to log a mild mild mild complaint, and not a whine.

I have found at this site confusion at times.

For example at one point I indicated that perhaps lasers could be used to alter the course of Comets, or to "Ping" them to see what their chemical spectrum is. I was told that there is no way to keep the focus in order to do that. And yet I will over and over again read articles that indicate that serious thinkers believe that it might be possible to
propell a spacecraft between stars solely with lasers. (And to slow them down as well).

Now I understand that likely the problem includes the catch that to propel a spacecraft to a star and slow it down you would need some futuristic focusing device such as does not now exist.

However I might make the point that no Orion Propulsion system exists, but we can talk about it.

So anyway have a nice weekend, I am not angry.

But if you like please clairify, or make better understood what you are communicating about the non-value of solar propulsion in interstellar travel.

Tom Kalbfus · 2014-06-07 01:27:37

The thing about Orion type propulsion systems is we already know how to make a fusion bomb, but we don't know how to do controlled fusion such that the output energy is greater than the input energy to start and maintain the fusion reaction. To make an Orion Fusion starship the main thing we need to do I build very large starships in space and a lot of hydrogen bombs. The conservative Orion Fusion spaceships take about 1000 years to reach the nearest star, so if we are going to have a 1000 year generation ship, its going to need to be big anyway. So according to the energy limited design a 50 gigaton O'Neill Cylinder will require 150 gigatons of thermonuclear bombs to propel it up to 1000 km/sec. To get two cylinders up to that speed, you need 300 gigatons of fusion bombs, 100 ton bombs and I believe about 50 kg of plutonium each to detonate each fusion bomb. You need 150 million tons of plutonium.

Void · 2014-06-07 08:58:59

A suggestion I would make would be to send a minimized version to an undifferentiated comet using solar sailing, and to then recycle the sail and also use the materials of the comet to expand the habitat. Also recycle the materials of the sail.

Begin constructing a hollow world habitat on the comet as a side purpose of the mission, and to obtain materials to expand the habitat.

Also construct the Orion propulsion device with materials from rocky objects, the Moon and Mars being primary candidates for that.

Tow the Orion propulsion unit to the comet spoken of previously, with another solar sail, and then outfit the mission. Recycle that solar sail as well.

At that point one achievement of human habitation of another world would have happened.

From that perch then launch your mission to another star system, I presume.

I suggest a metamorphic process, where the effort changes methods, as useful, "Living off the land" as might be possible.

I suggest that the population does not need to be huge, because genetic diversity can be supplemented by the storage of diverse genomes by current methods, (Frozen Embrio's), or some futuristic method, even perhaps uploading patterns and printing DNA.

The average population should be crafted to be compatible with the various segments of the mission.

With the completion of the Orion thrust to maximum speed, then the population would then make a metamorphic transformation of the mass of the ship to perhaps gear up for magnetic braking.

That magnetic breaking if successful would leave the ship in a elliptical orbit around the host star. That elliptical orbit might then allow them to find a suitable comet around that star system, and they would then construct a hollow world, and expand their population.

From there that population would work to expand into that star systems resources whatever they were.

I might certainly be wrong, but I hope that even a binary star would have comets around it far out in an Oort cloud.

And please understand I want to be helpful, and I don't mind criticism, but I might be forced to request definition of that criticism so that I can learn.

Tom Kalbfus · 2014-06-07 12:17:38

There are two ways to look at interstellar colonization, one way is destination centric, that is about 10,000 people hunker down in a small generation ship waiting for the day that their children or grand children get to explore that distance system they are heading for.

The other point of view is that a community lives on a multigeneration ship and that everytime they pass through a star system they have an opportunity to offload excess population.

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