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Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Interstellar Ark

I've designed an Interstellar Ark, its dimensions are as follows, it consists of 108 cylinders clustered together within a radius of 1,100 km with the walls of each cylinder almost touching each other. Each cylinder is 100 km in diameter and 20,000 km long. The cylinders each rotate to provide 1 g of simulated gravity on their inner surfaces. Nestled inside each cylinder is a ceiling cylinder 80 km in diameter with a troposphere in between the inner and outer cylinder. From the inner cylinder comes artificial sunlight the power for which is provided by nuclear fusion reactors that also provide power for the fusion drive. acceleration is 1 cm per second squared. Also within that space is the fuel tank. The living space within the cylinders is 678,584,013 km^2. The surface area of the Earth is about 510 million square km.

Travel times, final velocities, and distances
1,000 seconds (16.67 minutes), 10 meters per second, 5 km
10,000 seconds (2.78 hours), 100 meters per second, 500 km
100,000 seconds (1.16 days), 1 km per second, 50,000 km
1,000,000 seconds (11.57 days), 10 km per second, 5,000,000 km
10,000,000 seconds (115.74 days) 100 km per second, 3.34 AU
100,000,000 seconds (3.169 years) 1,000 km per second, 333.34 AU
1,000,000,000 seconds (31.689 years) 10,000 km per second (3.34% of the speed of light), 0.526 light years.

A trip to Alpha Centauri 4.4 light years 100.240 years cruise + 2 * 31.689 years accel. = 163.618 years.

Last edited by Tom Kalbfus (2013-12-04 22:40:25)

Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Re: Interstellar Ark

If we could use carbon nanotubes, then 100 radius cylinders should be possible. Having 108 of them that are 20,000 km long should produce an area greater than Earth.

I got this from this website:
http://cosmoquest.org/forum/archive/ind … 11850.html

Iron asteroids could be used to create large iron or steel shells, assuming that carbon nanotubes are not available.

If carbon nanotubes were available in bulk then (according to McKendree) the largest possible cylinder would have a radius of 960 km, or a diameter of nearly 2000km. That is assuming a tensile strength of 50 Gpa (in fact it may be as high as 68 Gpa), a safety factor of 50%, and no payload (ie no internal fixtures and fittings, and no people).

Assuming that the slightly higher strength is feasible, and that a slightly lower safety factor is possible, and lower gravity is acceptable then one should be able to build a Bishop Ring 2000km across
http://en.wikipedia.org/wiki/Bishop_Ring_%28habitat%29
http://www.orionsarm.com/eg-article/460db7f55a8d3

From the Bishop_Ring Artical:

A Bishop Ring is a type of hypothetical rotating space habitat originally proposed in 1997 by Forrest Bishop.[1] Like other space habitat designs, the Bishop Ring would spin to produce artificial gravity by way of centripetal force. The design differs from the classical designs produced in the 1970s by Gerard K. O'Neill and NASA in that it would use carbon nanotubes instead of steel, allowing the habitat to be built much larger. In the original proposal, the habitat would be approximately 1,000 km (620 mi) in radius and 500 km (310 mi) in width, containing 3 million square kilometers (1.2 million square miles) of living space,[1] comparable to the area of Argentina or India.
Because of its enormous scale, the Bishop Ring would not need to be enclosed like the Stanford torus: it could be built without a "roof", with the atmosphere retained by artificial gravity and atmosphere retention walls some 200 km (120 mi) in height.[1] The habitat would be oriented with its axis of rotation perpendicular to the plane of its orbit, with either an arrangement of mirrors to reflect sunlight onto the inner rim or an artificial light source in the middle, powered by a combination of solar panels on the outer rim and solar power satellites.[1]
Also unlike the 1970s NASA proposals, where habitats would be placed in cislunar space or the Earth-Moon L₄/L₅ Lagrangian points, Forrest Bishop proposed the much more distant Sun-Earth L₄/L₅ Lagrangian points as the sites for the habitats.[1]

Each of the cylinders I'm talking about are only 100 km in diameter, a cluster of them 1100 km in diameter will fit 108 of them, and unlike the Bishop Ring, this arrangement will give a surface area greater than Earth, although this surface area is divided up into 108 cylinders. A Bishop Ring wastes a lot of space that is just vacuum. I think even within the volume of a 100 km cylinder, there is plenty of room for hydrogen tanks and a fusion reactor. Each cylinder is in effect its own starship, but all 108 starships are lashed together to maintain stability, as a cylinder 20,000 km long will tend to end up flipping end over end if things get unbalanced. Using O'Neill's solution to mate two cylinders together with each rotating in opposite directions, we have 54 pairs of cylinders in this cluster and through the center of each cylinder is a fusion rocket surrounded by hydrogen tanks that serve to provide both fuel and reaction mass for this starship.

You may ask, why the cylinders are 20,000 km long? They are that long because that is the approximate distance between Earth's poles along Earth's curvature. As you may recall, the original definition of a meter was that it was 1/10,000,000th the distance from the equator to the pole, the people who devised the metric system were a little off, but 20,000 km from pole to pole is close enough. You see I want to have cylinders with 365 seasonal cycles which are long enough to accomocate migrating animals, such as birds that fly south for the winter for instance, usually the direction of migrations are either north or south so these cylinders are very long and the ends will be cold with arctic conditions, while the middle part of each cylinder will be tropical.

It is possible to travel from cylinder to cylinder using O'Neill's idea of a Commuter Sphere. Nestled on the curved bottom is each cylinder floor is a docking port. A commuter sphere docks with the docking port, passengers enter the sphere through a docking ring and climb into their seats, putting on seat belts, then they wait in the commuter sphere for the right moment when the sphere undocks and drops away on a tangential path towards the floor and docking port of another cylinder. The commuter sphere executes a 180 roll while it is moving in the space between cylinders, and then docks with the empty commuter sphere port of the destination cylinder. Once docked the double doors of the commuter sphere and the docking port open up to allow the passengers to egress and enter the environment of the new cylinder. There are 108 such cylinders they can visit, each one 100 km wide by 20,000 km long, each one a separate world onto itself.

Here is a link showing the arrangement of these cylinders:
http://groups.yahoo.com/neo/groups/theh … 1609540981

Last edited by Tom Kalbfus (2013-12-05 11:36:28)

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,389

Re: Interstellar Ark

While searching for "ark", I found this topic that was created and then has been idle for 7 years or so ...

The recent work of Quaoar to investigate laser pumped transport to Proxima Centauri is about interstellar travel.  The post here is about travelling for longer periods that would be possible with Quaoar's method, but it ** does ** include consideration of the accommodations that would be necessary for a long journey.

In any case, this is a good time to bring this ancient topic back into view.

(th)