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Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Bishop Ring Colony inside the Moon

This is a Bishop Ring

https://en.wikipedia.org/wiki/Bishop_Ring_%28habitat%29

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]

One thing that occurred to me is that a Bishop ring is 1000 km in radius, the moon is 1738 km in radius. What if someday, we made a larger version of this Bishop ring, one that was about 1720 km in radius, build within the Moon. According to the description, Bishop rings have artificial illumination anyway, and they require advanced carbon nanotubes to be strong enough to hold together, but not if we pile Lunar regolith on top of them as they spin, under lunar gravity. Basically we need 6 times the mass of the Bishop Ring in Lunar material using Lunar gravity to hold it together as it spins inside the Moon. Most of the Moon need not be excavated for this, only a tunnel to allow the Bishop ring to spin inside under magnetic fields from above to maglev it towards the Moon's center. Another idea is that Part of the ring need not have Lunar material above it holding it down. Basically we bracket it from left and right, but the middle of the band would be exposed to vacuum, and it is where we would place the space ports of this ring habitat. Ships woud approach the rign tangentially at the rings spin velocity, and then dock with the underside ports of the Bishop ring, and then travel through the floor under the equivalent of 1 Earth gravity to enter the environment within.

Last edited by Tom Kalbfus (2016-02-21 10:46:09)

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 28,884

Re: Bishop Ring Colony inside the Moon

What is not self evident is the means to make it spin, keep it from wobbling and how it is powered for the colonists.

The mehods for construction are no different than any other large scale project only difference is where the insitu resource are coming from.

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Bishop Ring Colony inside the Moon

Lets say this Bishop Ring is 1738 km in radius, and is around the Moon's equator, it would have to spin to create 116.5% of Earth's gravity, subtract the Lunar gravity to get an outward Earth Gravity of centrifugal force. A person standing upsidedown at the center of the ring band would experience 1 Earth gravity as one moves upward, the centrifugal force becomes proportionally less. If the atmospheric Pressure is the same as on Earth at sea level, and it has the same composition, then there will be about 8 kilometers of breathable air above one's head. If the Bishop ring surface matches the curvature of the Moon, then how wide would the inhabitable area be? Subtract 8 km from 1738 km to get 1780 km, and that is the cosine times the Moons radius of your latitude. 1730/1738 = 0.99539700805523590333716915995397
Find the inverse cosine of that number to get latitudes north and south, which is 5.4995159540989730511249463616632 degrees north and south of the Lunar equator 1738 * sin of that number is 166.56530250925611067741531708 km, the band would be 333.13060501851222135483063416 km wide, this is roughly 200 miles wide.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 28,884

Re: Bishop Ring Colony inside the Moon

I think we ran the same numbers there abouts with a railcar traveling as you put it around the moons equator. It was not all that fast to achieve the needed RPM / MPH for gravity of 1 G to occur.

Much like our dome issue for the mass of the atmosphere pressing on the floor it will try to press the dome off from that floor with a 1 bar level. I agree on the surface we would need to land and then travel to the entrance to get into the ring that will be traveling over head. By playing catchup to the entrance and then linking up once there by moving on a parallel path to the ring.

karov

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From: Bulgaria

Registered: 2004-06-03

Posts: 953

Re: Bishop Ring Colony inside the Moon

A clear example of how seamless is the spectrum between "natural" gravity habitats and rotating ones.
A massive underbody counters the centrifugal force with its gravity and lets the maxium radius of the habitat to be proportionally bigger within using the same materials.
Imagine a combination of a Bishop ring and a Birch's band habitat around a massive underbody.
The former kinetically supporting the later.
The Bishop ring serving as orbital ring / toposphere / for the maglev-ed Birch band on top of it.
The first facing the underbody, the later - the stars...

Antius

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From: Cumbria, UK

Registered: 2007-05-22

Posts: 1,003

Re: Bishop Ring Colony inside the Moon

I think it unlikely that any future society would attempt to build a Bishop's Ring habitat around the entire circumference of the moon.  Far more likely that lunar surface habitats (if any) will grow on a more incremental basis, i.e. smaller carousel type structures in non-rotating masonry structures above or just beneath the surface.

A global Bishop's Ring would be like trying to build an entire world all at once.  Real human projects don't work like that.  Cities start small and grow bigger incrementally, over a course of centuries as investments gradually accumulate.  That is the sort of development we should expect as humans move out into space.  They won't be trying to build planet size structures all at once, they will start small, with future generations building on the work of previous generations, such that structures will grow akin to a living organism.

Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Re: Bishop Ring Colony inside the Moon

I think we ran the same numbers there abouts with a railcar traveling as you put it around the moons equator. It was not all that fast to achieve the needed RPM / MPH for gravity of 1 G to occur.

Much like our dome issue for the mass of the atmosphere pressing on the floor it will try to press the dome off from that floor with a 1 bar level. I agree on the surface we would need to land and then travel to the entrance to get into the ring that will be traveling over head. By playing catchup to the entrance and then linking up once there by moving on a parallel path to the ring.

I think previously I was talking about, a rotating habitat that rotated enough to travel around the Moon, once every 24 hours, for a 24-hour day/night cycle, for centrifugal force, the spin rate would have to be much faster.

According to this calc tool http://www.calctool.org/CALC/phys/newtonian/centrifugal , a rotation rate at the Moon's equator of 40.85 minutes would produce a net 1-G of outward centrifugal force. this produces an outward acceleration of 1.16467-G, the part after the decimal point is negated by the Moon's gravity. What we would need is a smooth track that is 200 miles wide. We would need to excavate the regolith and make a ditch, flattening mountains and filling in craters as we go, place an upside down maglev track in the ditch, and then an inverted Bishop ring, Under the circumstances a ceiling to hold in atmosphere would be preferable, with perhaps walls that are 10 km tall, this holds in the breathable portion of our atmosphere. We pile lunar regolith on top of the outward facing underside of the maglev track, making sure that the mass of all that rock is about 6 times the mass of the Bishop Ring that is spun, that way the downward weight of the rock equals the upward centrifugal force of the spinning ring, and the bishop ring doesn't break apart, and all that is left to do is simply anchor the who apparatus to the Lunar bedrock so it stays put. And if one wants, We could float another 200 mile wide ring habitat on top, this one only rotates once every 24 hours, it could be a park under lunar gravity, people wouldn't live there so much as visit. We could adapt various plants, and animals to this Lunar gravity, and people can visit from the faster rotating Bishop ring, and have some bouncy lunar fun, in the low gravity!