- #1
Strato Incendus
- 182
- 23
This is a topic that will be relevant for anyone who plans to use "realistic" artificial gravity (of the centrifugal kind, rather than the "acceleration-based" kind) in their stories - be it on spaceships or space stations:
How much of the ring walls has to be dedicated to radiation shielding?
(Assuming we would want to use water for shielding, since it has several advantages over e.g. a titanium shield.)
One scene in my story that used to be set on one of the rings of an interstellar spaceship would benefit from having the ring be a little wider - in terms of usable living space. (Some people are practicing to shoot with a bow and arrow, in case enough technology fails and they have to hunt with primitive means on the target planet again.
Google tells me that common shooting distances for archery competitions range from 18 to 70 metres (even though the overall range of the bow is of course much longer).
Shooting arrows along the curvature of the ring might not be a problem for the curvature itself, given the ring diametre of 500 metres (and the resulting circumference), depending on which deck you're standing on. But as I've been told by other users in past threads, projectiles of any kind will respond differently, depending on whether you should spinward or anti-spinward. Thus, shooting across the ring's width would be the closest approximation to shooting arrows on the surface of a planet.
So far, my rings have an inner width of 32 metres, an outer width of 64 metres. Meaning, the wall on each side is half as thick as the usable space in between (16 metres of shielding in both directions). The main reason for this was that I included security doors that can shut off sections of the ring, and those 16-metre-wide doors (which meet in the middle to block the corridor) need to fit into the walls.
Of course, their width could be reduced by having the doors consist of several segments that slide into each other. Another way to get more usable space inside each ring would be to essentially have the whole 64 metres as inner width; and then, only at the section doors, you'd have a setup (across the corridor) of: 16-metre-wide wall (containing the left door), 32-metre corridor, 16-metre-wide wall (containing the right door).
In short: Getting more usable space within the rings is actually the easy part.
What's harder to determine is how much wall I still need to reserve for shielding against all kinds of cosmic radiation.
Having 16-metre wide walls full of water on both sides of the ring seemed so excessive to me, but apparently, it's not: This article claims one would need at least a 5-metre-thick water shield, and even that wouldn't be enough to protect against secondary gamma radiation and muonic radiation. So how much shielding do I need against those?
Note that, in my ship design, the rings themselves are in between two large spheres with twice the diameter of the rings, and those large spheres contain a bunch of water tanks. The rings are perpendicular to the axis of the ship. So where otherwise, particularly hard radiation from the front (due to travelling at relativistic speeds) would hit the ring walls, the rings are already shielded against that by the water tanks in the fore and aft sphere. Obviously, this protection is required on both ends, since the ship will turn around for braking.
So in my case, we're really only talking about the thickness of water shielding required against the remaining cosmic radiation - the kind that hits the ship from all sides.
We would therefore probably also need a water shield in the floor of the ring (pointing outward).
The question is: Would we also need water shielding in the ceiling? Since that's the part of the ring pointing inwards. So there's already lots of protective water on the other side of the ring. But of course, the radiation doesn't hit the rings at a straight angle only. So the ceiling would almost definitely also require the same amount of water shielding as the walls and the bottom floor of each ring.
How much of the ring walls has to be dedicated to radiation shielding?
(Assuming we would want to use water for shielding, since it has several advantages over e.g. a titanium shield.)
One scene in my story that used to be set on one of the rings of an interstellar spaceship would benefit from having the ring be a little wider - in terms of usable living space. (Some people are practicing to shoot with a bow and arrow, in case enough technology fails and they have to hunt with primitive means on the target planet again.
Google tells me that common shooting distances for archery competitions range from 18 to 70 metres (even though the overall range of the bow is of course much longer).
Shooting arrows along the curvature of the ring might not be a problem for the curvature itself, given the ring diametre of 500 metres (and the resulting circumference), depending on which deck you're standing on. But as I've been told by other users in past threads, projectiles of any kind will respond differently, depending on whether you should spinward or anti-spinward. Thus, shooting across the ring's width would be the closest approximation to shooting arrows on the surface of a planet.
So far, my rings have an inner width of 32 metres, an outer width of 64 metres. Meaning, the wall on each side is half as thick as the usable space in between (16 metres of shielding in both directions). The main reason for this was that I included security doors that can shut off sections of the ring, and those 16-metre-wide doors (which meet in the middle to block the corridor) need to fit into the walls.
Of course, their width could be reduced by having the doors consist of several segments that slide into each other. Another way to get more usable space inside each ring would be to essentially have the whole 64 metres as inner width; and then, only at the section doors, you'd have a setup (across the corridor) of: 16-metre-wide wall (containing the left door), 32-metre corridor, 16-metre-wide wall (containing the right door).
In short: Getting more usable space within the rings is actually the easy part.
What's harder to determine is how much wall I still need to reserve for shielding against all kinds of cosmic radiation.
Having 16-metre wide walls full of water on both sides of the ring seemed so excessive to me, but apparently, it's not: This article claims one would need at least a 5-metre-thick water shield, and even that wouldn't be enough to protect against secondary gamma radiation and muonic radiation. So how much shielding do I need against those?
Note that, in my ship design, the rings themselves are in between two large spheres with twice the diameter of the rings, and those large spheres contain a bunch of water tanks. The rings are perpendicular to the axis of the ship. So where otherwise, particularly hard radiation from the front (due to travelling at relativistic speeds) would hit the ring walls, the rings are already shielded against that by the water tanks in the fore and aft sphere. Obviously, this protection is required on both ends, since the ship will turn around for braking.
So in my case, we're really only talking about the thickness of water shielding required against the remaining cosmic radiation - the kind that hits the ship from all sides.
We would therefore probably also need a water shield in the floor of the ring (pointing outward).
The question is: Would we also need water shielding in the ceiling? Since that's the part of the ring pointing inwards. So there's already lots of protective water on the other side of the ring. But of course, the radiation doesn't hit the rings at a straight angle only. So the ceiling would almost definitely also require the same amount of water shielding as the walls and the bottom floor of each ring.
