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Safehold's Moon, orbit of bombardment platform, etc.?

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Safehold's Moon, orbit of bombardment platform, etc.?
Post by Ensign Re-read   » Mon Apr 03, 2017 12:17 pm

Ensign Re-read
Commodore

Posts: 763
Joined: Thu Apr 08, 2010 4:24 pm

I'm trying to update the Celestia plug-in for Safehold in advance of Manticon 2017.



One of the things that is missing from the current plug-in is any place-holder for Safehold's Moon (or Moon_s_) as well as the Orbital Bombardment Platform.

* Can anyone cite a reference in the books for how many moons there are, how often it (they) orbit, etc.?

* Likewise, is there any reference to how often the OBP passes over any given point on the planet, and/or any other information that can infer an orbit's location?


ERR
.
=====
The Celestia "addon" for the Planet Safehold as well as the Kau-zhi and Manticore A-B star systems, are at URL:
http://www.lepp.cornell.edu/~seb/celestia/weber/.
=====
http://www.flickr.com/photos/68506297@N ... 740128635/
=====
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Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by DrakBibliophile   » Mon Apr 03, 2017 7:05 pm

DrakBibliophile
Admiral

Posts: 2125
Joined: Sun Sep 06, 2009 3:54 pm
Location: East Central Illinois

Safehold has a large moon which according to David Weber is
somewhat larger than our moon and it's albedo is considerably brighter than our moon.

Note, this moon has been mentioned as existing in text and in the "Safehold time keeping" notes at the end of many of the books.

As for additional moons, none have been mentioned by David Weber or in the text.

As for the OBP, David Weber has been extremely vague about it (or them).

Ensign Re-read wrote:I'm trying to update the Celestia plug-in for Safehold in advance of Manticon 2017.



One of the things that is missing from the current plug-in is any place-holder for Safehold's Moon (or Moon_s_) as well as the Orbital Bombardment Platform.

* Can anyone cite a reference in the books for how many moons there are, how often it (they) orbit, etc.?

* Likewise, is there any reference to how often the OBP passes over any given point on the planet, and/or any other information that can infer an orbit's location?


ERR
.
*
Paul Howard (Alias Drak Bibliophile)
*
Sometimes The Dragon Wins! [Polite Dragon Smile]
*
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Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Ensign Re-read   » Tue Apr 04, 2017 9:09 pm

Ensign Re-read
Commodore

Posts: 763
Joined: Thu Apr 08, 2010 4:24 pm

DrakBibliophile wrote:Safehold has a large moon which according to David Weber is
somewhat larger than our moon and it's albedo is considerably brighter than our moon.

==CLIP==


OK, then I'll insert our own moon, maybe tweak the albedo (a value I'll have to look up), and bump up the size.

Exact percentage TBD; I'll accept nominations!



DrakBibliophile wrote:As for the OBP, David Weber has been extremely vague about it (or them).


OK then, I'll insert the ISS in place of the OBP.
If anyone doesn't like that, they can build their own.


p.s.: If I should EVER re-figure out how to post images (Flickr, etc.), are there any points of view that people would like to see still images of?
{Sorry, no clouds or shimmering oceans.}

.
=====
The Celestia "addon" for the Planet Safehold as well as the Kau-zhi and Manticore A-B star systems, are at URL:
http://www.lepp.cornell.edu/~seb/celestia/weber/.
=====
http://www.flickr.com/photos/68506297@N ... 740128635/
=====
Top
Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Ensign Re-read   » Tue Apr 04, 2017 9:51 pm

Ensign Re-read
Commodore

Posts: 763
Joined: Thu Apr 08, 2010 4:24 pm

Ensign Re-read wrote:p.s.: If I should EVER re-figure out how to post images (Flickr, etc.), are there any points of view that people would like to see still images of?
{Sorry, no clouds or shimmering oceans.}



Experiment - Does this link work?:
https://flic.kr/p/Tvg1XK

If yes then, inserting the image into Forum Message will come next.


.
=====
The Celestia "addon" for the Planet Safehold as well as the Kau-zhi and Manticore A-B star systems, are at URL:
http://www.lepp.cornell.edu/~seb/celestia/weber/.
=====
http://www.flickr.com/photos/68506297@N ... 740128635/
=====
Top
Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Joat42   » Wed Apr 05, 2017 1:48 pm

Joat42
Commodore

Posts: 803
Joined: Tue Apr 16, 2013 7:01 am
Location: Sweden

Ensign Re-read wrote:
Ensign Re-read wrote:p.s.: If I should EVER re-figure out how to post images (Flickr, etc.), are there any points of view that people would like to see still images of?
{Sorry, no clouds or shimmering oceans.}


Experiment - Does this link work?:
https://flic.kr/p/Tvg1XK

If yes then, inserting the image into Forum Message will come next.

Link works fine. Remember there is a width-limit on embedded images (I think it is ~700px).

Regarding the OBS some think it's multiple platforms so it can easily cover the whole of Safehold, but as mentioned earlier there is no hard facts available.

---
Jack of all trades and destructive tinkerer.
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Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Louis R   » Wed Apr 05, 2017 2:20 pm

Louis R
Commodore

Posts: 993
Joined: Thu Jan 01, 2015 9:25 pm

That worked fine. Are you able to guestimate the latitude of the northern and southern edges of the map when you do that? They aren't the same distance from the equator, so one or both of them lie short of the poles [my BOE guess puts them around +70/-65, but the assumptions made are suspect]

AFAIK, we haven't been told the relation between a lunar month and a calendar month, so there's nothing on orbital parameters. There is one bit on the size/albedo combo, though: Harless' attack on Thesmar. IIRC it was timed to start shortly before moonrise, which in turn was about 1 hour before sunrise. That moonrise was expected to provide a significant amount of light, which would definitely _not_ be the case on Earth. Moonrise within an hour of sunrise puts the moon 12-15 degrees from the sun, which is a very narrow crescent - in fact, it's what most people call a 'new moon' - and even with snow-covered ground in a dark-sky site I've always seen more light from twilight than from a moon that close to new. Safehold's moon has to be both larger and a _lot_ more reflective. Which doesn't mean mirror-bright by any means, since Luna is only 13.6%

Ensign Re-read wrote:
Ensign Re-read wrote:p.s.: If I should EVER re-figure out how to post images (Flickr, etc.), are there any points of view that people would like to see still images of?
{Sorry, no clouds or shimmering oceans.}



Experiment - Does this link work?:
https://flic.kr/p/Tvg1XK

If yes then, inserting the image into Forum Message will come next.


.
Top
Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Ensign Re-read   » Wed Apr 05, 2017 6:05 pm

Ensign Re-read
Commodore

Posts: 763
Joined: Thu Apr 08, 2010 4:24 pm

Louis R wrote:That worked fine. Are you able to guestimate the latitude of the northern and southern edges of the map when you do that? They aren't the same distance from the equator, so one or both of them lie short of the poles [my BOE guess puts them around +70/-65, but the assumptions made are suspect]

AFAIK, we haven't been told the relation between a lunar month and a calendar month, so there's nothing on orbital parameters. There is one bit on the size/albedo combo, though: Harless' attack on Thesmar. IIRC it was timed to start shortly before moonrise, which in turn was about 1 hour before sunrise. That moonrise was expected to provide a significant amount of light, which would definitely _not_ be the case on Earth. Moonrise within an hour of sunrise puts the moon 12-15 degrees from the sun, which is a very narrow crescent - in fact, it's what most people call a 'new moon' - and even with snow-covered ground in a dark-sky site I've always seen more light from twilight than from a moon that close to new. Safehold's moon has to be both larger and a _lot_ more reflective. Which doesn't mean mirror-bright by any means, since Luna is only 13.6%


Thanks for the input, keep it coming.
I'll pass along your comment to Selden.
Later this week (tonight maybe?) I'll try updating the .ssc text.


Slight topic shift:
* How many of you have actually installed and used Celestia and the plug in?
* Of those, who would be interested in seeing some half-done work?


.
=====
The Celestia "addon" for the Planet Safehold as well as the Kau-zhi and Manticore A-B star systems, are at URL:
http://www.lepp.cornell.edu/~seb/celestia/weber/.
=====
http://www.flickr.com/photos/68506297@N ... 740128635/
=====
Top
Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by MuonNeutrino   » Thu Apr 06, 2017 12:39 pm

MuonNeutrino
Commander

Posts: 161
Joined: Tue Aug 06, 2013 12:40 pm

Regarding the bombardment system, we get a few clues in OAR when Merlin is discussing trying to take it out with Owl (pp. 134-135). Two notable tidbits:

Owl describes the layout of the system as "the kinetic bombardment and solar energy platforms are nested in the center of a sphere of area defense systems and passive scanners". This suggests to me that the bombardment system, while composed of multiple platforms, is *not* a highly dispersed system englobing the planet from all angles, but rather is a single discrete unit. (Or, at least, that the *bombardment* part is - the surveillance parts of it may still be dispersed to avoid blind spots.)

A SNARC that tried to sneak closer to the system under stealth was detected and destroyed "while it was still thousands of kilometers from the platforms". This imples that the system reacts to any technological vessel that gets too close to it; however, Merlin seems to operate SNARCs with impunity in atmosphere and low orbit, and also takes trips to low orbit in the skimmer. It's noted that the bombardment system doesn't seem to react to the *emissions* of the skimmers or SNARCs, but it seems to react to *proximity*. Thus, I would assume that the bombardment system isn't in low orbit, or indeed any orbit that is within 'thousands of kilometers' of the surface - otherwise, SNARCs and skimmers in low orbit would be within its defensive perimeter.

Outside of low orbit, we should ask 'what sorts of orbit might be most useful for the bombardment system's purposes?' If it really is a non-dispersed system, it needs to be in an orbit that allows it to cover any location on the planet's surface, ideally without untoward delays so that it can smite heretics as quickly as possible once triggered. (For example, this should rule out geostationary orbit, since that would leave it permanently unable to cover an entire hemisphere of the planet.) This requirement suggests a polar orbit so that it can cover all latitudes, and likely one that is notably below geosynch so it doesn't take too long. For example, a polar orbit with a period of 1/2 of the planet's rotation period would pass over each quadrant of the planet's surface once per local day, one with a period of 1/3 the rotation period would pass over each third of the planet's surface twice per day, and one with a period of 1/4 the rotation period would pass over each eighth of the planet's surface once per day. For Earth those orbits would be at altitudes (not radii!) of ~20200 km, ~13900 km, and ~10400 km respectively. I don't know exactly how massive safehold is, but those altitudes probably wouldn't be *grossly* different for it. (And they're easy to re-calculate if needed.)

I don't think we have any particular evidence that would allow us to narrow it down any further, but if I were constructing such a model I'd place the bombardment system in a polar orbit somewhere around 10,000 - 20,000 km from the surface.

(Hi again!)
_______________________________________________________
MuonNeutrino
Astronomy grad student, gamer, and procrastinator extraordinaire
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Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by Louis R   » Thu Apr 06, 2017 2:26 pm

Louis R
Commodore

Posts: 993
Joined: Thu Jan 01, 2015 9:25 pm

That scene doesn't actually show that there's only the one orbital complex - any others probably wouldn't be mentioned since we're not being given a complete description of the system. So that part is kind of open.

I'd probably use Molniya-style orbits for the system, with 2 or 3 sets of orbital platforms. At the time it was emplaced, there were very few [as in 1-3] settlements below the equator, and it sounds as if the War was primarily fought on Haven, so the designers could have gone for maximum northern hemisphere hang time.

MuonNeutrino wrote:Regarding the bombardment system, we get a few clues in OAR when Merlin is discussing trying to take it out with Owl (pp. 134-135). Two notable tidbits:

Owl describes the layout of the system as "the kinetic bombardment and solar energy platforms are nested in the center of a sphere of area defense systems and passive scanners". This suggests to me that the bombardment system, while composed of multiple platforms, is *not* a highly dispersed system englobing the planet from all angles, but rather is a single discrete unit. (Or, at least, that the *bombardment* part is - the surveillance parts of it may still be dispersed to avoid blind spots.)

A SNARC that tried to sneak closer to the system under stealth was detected and destroyed "while it was still thousands of kilometers from the platforms". This imples that the system reacts to any technological vessel that gets too close to it; however, Merlin seems to operate SNARCs with impunity in atmosphere and low orbit, and also takes trips to low orbit in the skimmer. It's noted that the bombardment system doesn't seem to react to the *emissions* of the skimmers or SNARCs, but it seems to react to *proximity*. Thus, I would assume that the bombardment system isn't in low orbit, or indeed any orbit that is within 'thousands of kilometers' of the surface - otherwise, SNARCs and skimmers in low orbit would be within its defensive perimeter.

Outside of low orbit, we should ask 'what sorts of orbit might be most useful for the bombardment system's purposes?' If it really is a non-dispersed system, it needs to be in an orbit that allows it to cover any location on the planet's surface, ideally without untoward delays so that it can smite heretics as quickly as possible once triggered. (For example, this should rule out geostationary orbit, since that would leave it permanently unable to cover an entire hemisphere of the planet.) This requirement suggests a polar orbit so that it can cover all latitudes, and likely one that is notably below geosynch so it doesn't take too long. For example, a polar orbit with a period of 1/2 of the planet's rotation period would pass over each quadrant of the planet's surface once per local day, one with a period of 1/3 the rotation period would pass over each third of the planet's surface twice per day, and one with a period of 1/4 the rotation period would pass over each eighth of the planet's surface once per day. For Earth those orbits would be at altitudes (not radii!) of ~20200 km, ~13900 km, and ~10400 km respectively. I don't know exactly how massive safehold is, but those altitudes probably wouldn't be *grossly* different for it. (And they're easy to re-calculate if needed.)

I don't think we have any particular evidence that would allow us to narrow it down any further, but if I were constructing such a model I'd place the bombardment system in a polar orbit somewhere around 10,000 - 20,000 km from the surface.

(Hi again!)
Top
Re: Safehold's Moon, orbit of bombardment platform, etc.?
Post by DrakBibliophile   » Thu Apr 06, 2017 5:36 pm

DrakBibliophile
Admiral

Posts: 2125
Joined: Sun Sep 06, 2009 3:54 pm
Location: East Central Illinois

In How Firm A Foundation, Merlin visits "Castaway Islands" in the Great Western Ocean to test the platforms' response to Steam Power.

By the description, those islands were very far to the South of Safehold so Merlin had to expect that the platforms could hit those islands if they were programmed to react to Steam Power.

Louis R wrote:That scene doesn't actually show that there's only the one orbital complex - any others probably wouldn't be mentioned since we're not being given a complete description of the system. So that part is kind of open.

I'd probably use Molniya-style orbits for the system, with 2 or 3 sets of orbital platforms. At the time it was emplaced, there were very few [as in 1-3] settlements below the equator, and it sounds as if the War was primarily fought on Haven, so the designers could have gone for maximum northern hemisphere hang time.

MuonNeutrino wrote:Regarding the bombardment system, we get a few clues in OAR when Merlin is discussing trying to take it out with Owl (pp. 134-135). Two notable tidbits:

Owl describes the layout of the system as "the kinetic bombardment and solar energy platforms are nested in the center of a sphere of area defense systems and passive scanners". This suggests to me that the bombardment system, while composed of multiple platforms, is *not* a highly dispersed system englobing the planet from all angles, but rather is a single discrete unit. (Or, at least, that the *bombardment* part is - the surveillance parts of it may still be dispersed to avoid blind spots.)

A SNARC that tried to sneak closer to the system under stealth was detected and destroyed "while it was still thousands of kilometers from the platforms". This imples that the system reacts to any technological vessel that gets too close to it; however, Merlin seems to operate SNARCs with impunity in atmosphere and low orbit, and also takes trips to low orbit in the skimmer. It's noted that the bombardment system doesn't seem to react to the *emissions* of the skimmers or SNARCs, but it seems to react to *proximity*. Thus, I would assume that the bombardment system isn't in low orbit, or indeed any orbit that is within 'thousands of kilometers' of the surface - otherwise, SNARCs and skimmers in low orbit would be within its defensive perimeter.

Outside of low orbit, we should ask 'what sorts of orbit might be most useful for the bombardment system's purposes?' If it really is a non-dispersed system, it needs to be in an orbit that allows it to cover any location on the planet's surface, ideally without untoward delays so that it can smite heretics as quickly as possible once triggered. (For example, this should rule out geostationary orbit, since that would leave it permanently unable to cover an entire hemisphere of the planet.) This requirement suggests a polar orbit so that it can cover all latitudes, and likely one that is notably below geosynch so it doesn't take too long. For example, a polar orbit with a period of 1/2 of the planet's rotation period would pass over each quadrant of the planet's surface once per local day, one with a period of 1/3 the rotation period would pass over each third of the planet's surface twice per day, and one with a period of 1/4 the rotation period would pass over each eighth of the planet's surface once per day. For Earth those orbits would be at altitudes (not radii!) of ~20200 km, ~13900 km, and ~10400 km respectively. I don't know exactly how massive safehold is, but those altitudes probably wouldn't be *grossly* different for it. (And they're easy to re-calculate if needed.)

I don't think we have any particular evidence that would allow us to narrow it down any further, but if I were constructing such a model I'd place the bombardment system in a polar orbit somewhere around 10,000 - 20,000 km from the surface.

(Hi again!)
*
Paul Howard (Alias Drak Bibliophile)
*
Sometimes The Dragon Wins! [Polite Dragon Smile]
*
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