Oort Clouds and Jump

[aramis]

Was crunching some numbers last night... want to re-crunch them here for sharing.

Pulling some data from wikipedia (because it's an easy source)...

The region can be subdivided into a spherical outer Oort cloud of 20,000–50,000 AU (0.32–0.79 ly), and a doughnut-shaped inner Oort cloud [Hill's Cloud] of 2,000–20,000 AU (0.03–0.32 ly).

The outer Oort cloud may have trillions of objects larger than 1 km (0.62 mi),[3] and billions with absolute magnitudes[14] brighter than 11 (corresponding to approximately 20-kilometre (12 mi) diameter), with neighboring objects tens of millions of kilometres apart.

The outer Oort (henceforth just Oort) is a trillion objects at least 1 km in diameter; and a billion at 20km.

Oort	radius	Vol
Ri	20,000.	33,510,321,638,291.1
Ro	50,000.	523,598,775,598,299.
Shell		490,088,453,960,008.
Small objects
NumObj	1,000,000,000,000.
Density (obj/au³	0.00204044798835763	=NumObj/VolShell
radius in AU	0.00000066889632107023	=100÷1495
area in AU²	0.00000000000044742229	=radius²
Area * density	0.00000000000000091294
P(avoid) per AU³	0.999999999999999	=1-area*density
crossing distance	30,000.	=Ro - Ri
P(avoid) per shell	0.999999999973355	=p(avoid per AU)^CrossingDist(in au)
20 km objects
NumObj	1,000,000,000.
Density (obj/au³	0.00000204044798835763	=NumObj/VolShell
radius in AU	0.0000133779264214047	=2000÷1495
area in AU²	0.00000000017896891534	=radius²
Area * density	0.00000000000000036518
P(avoid) per AU³	1.	=1-area*density
crossing distance	30,000.	=Ro - Ri
P(avoid) per shell	0.999999999990008	=p(avoid per AU)^CrossingDist(in au)
combined A*D	0.00000000000000127812	=small + large
P(avoid) per AU³	0.999999999999999	=1-combined
P(avoid) per shell	0.999999999960032	=p(avoid per AU)^CrossingDist(in au)

pretty safe.

And the Hill Cloud

20000-2000 = 18000 AU diameter donut, or 9000 AU tube radius centered on 11000 AU orbit.

10x the objects.

V=(πr²)(2πR)

Hill	radius	Vol
Ri	2,000.
Ro	20,000.
Rr	9,000.
RR	11,000.
Shell Vol	=(πr²)(2πRR)	17,587,635,042,741.2
Small objects
NumObj	1,000,000,000,000,000.
Density (obj/au³	56.8581277454196	=NumObj/VolShell
radius in AU	0.00000066889632107023	=100÷1495
area in AU²	0.00000000000044742229	=radius²
Area * density	0.00000000002543959363
P(avoid) per AU³	0.99999999997456	=1-area*density
crossing distance	18,000.	=Ro - Ri
P(avoid) per shell	0.999999542088396	=p(avoid per AU)^CrossingDist(in au)
20 km objects
NumObj	1,000,000,000,000.
Density (obj/au³	0.0568581277454196	=NumObj/VolShell
radius in AU	0.0000133779264214047	=2000÷1495
area in AU²	0.00000000017896891534	=radius²
Area * density	0.00000000001017583745
P(avoid) per AU³	0.999999999989824	=1-area*density
crossing distance	18,000.	=Ro - Ri
P(avoid) per shell	0.999999816834534	=p(avoid per AU)^CrossingDist(in au)
combined A*D	0.00000000003561543108	=small + large
P(avoid) per AU³	0.999999999964385	=1-combined
P(avoid) per shell	0.999999358923014	=p(avoid per AU)^CrossingDist(in au)

but note that the Hills cloud being in the way is only P=(22*2)/(2*11π)... roughly, P(hills in way)=0.6.

P(Oort Safe) 0.99999999996003200000
P(Hills Safe if in way) 0.99999935892301400000
P(Hills stops if in way) 0.00000064107698583005
P(hills in way) 0.636619772367581
P(Hills stops) 0.00000040812228478922
P(Hills net safe) 0.999999591877715
P shell 0.999999591837747
2nd system 0.999999183675661

So, the odds of an oort or hills stop on jump is roughly 8 in 10,000,000

And, just for fun... the odds of stop with a larger radius for shadowing?
take the ratio and square it, then multiply that 8 in 10million
so for 1000 diameters...8 in 100,000
for 10000 diameters, 8 in 1,000
for 100,000 diameters, 8%

 

[Carlobrand]

This presupposes that the Oorts, et al, or their equivalents around Trav stars are unmapped. That's a huge number of bodies in a huge volume to map, but if the goal is to clear specific routes from your star to the next, then the - radial velocities? - of those bodies may be low enough that an active continuous effort to detect and map bodies entering a specific transit corridor of diameter X - say wide enough to allow for the effect of the planet's orbit on the path to the next system - might be undertaken at reasonable expense and effort. At that point, it's simply a matter of keeping shipping informed of the corridor map as changes occur. It would take, what, something like a Hubble? Looking for the faint glimmer that might be an Oort body entering the monitored corridor region and then trying to get enough information to discern its motion and add it in to the system's ephemeris?

Of course, that's no help for a scout going to an unexplored system, and D/E starports likely don't offer that service. However, where there's enough traffic that a statistically rare event might actually occur once in 5 or 10 years somewhere in the Marches,

 

[aramis]

This presupposes that the Oorts, et al, or their equivalents around Trav stars are unmapped. That's a huge number of bodies in a huge volume to map, but if the goal is to clear specific routes from your star to the next, then the - radial velocities? - of those bodies may be low enough that an active continuous effort to detect and map bodies entering a specific transit corridor of diameter X - say wide enough to allow for the effect of the planet's orbit on the path to the next system - might be undertaken at reasonable expense and effort. At that point, it's simply a matter of keeping shipping informed of the corridor map as changes occur. It would take, what, something like a Hubble? Looking for the faint glimmer that might be an Oort body entering the monitored corridor region and then trying to get enough information to discern its motion and add it in to the system's ephemeris?

The dataset is going to be absolutely impossibly huge once you add hop-4 and hop-5 drives (which I suspect hop-1 circa Year 1400 in the OTU, based upon some comments from Marc, Greg, Don, and Robject)

When you're talking 30-50 Pc at a shot, and a trillion or more objects per system and 300 to 500 systems in range... it snowballs rapidly. Let alone once you add skip drives, at 100-900 Pc per skip...

 

[Ran Targas]

Never tell me the odds ...

I've been using Oort and Kuiper objects to cause mis-jumps for a long time. It's my favorite way to slow down speedy players who are rushing to leave the system they're in just because they think they're done (but I wrote this big adventure and made this cool map ...).

Sometimes I have a derelict craft stuck in or slowly orbiting the planetesimal (with value to someone back at the star port) or sometimes they pick up a faint signal drawing them back to where I want them to be. All the same, it's a useful bit of handwavium.

 

[Carlobrand]

The dataset is going to be absolutely impossibly huge once you add hop-4 and hop-5 drives (which I suspect hop-1 circa Year 1400 in the OTU ...

I'm figuring I've got about 300 years to figure out a solution for that one.

 

[Aramais]

Hop

Greg, at least, doesn't know when Hop-1 shows up. Greg is a mushroom: fed dung and kept in the dark. Greg is simply looking for a way to keep me relevant long after the Golden Age is done.

Aramais P. Lee

 

[Aramais]

What I DO know is that Hop and antimatter power will tend to come together, and this will favor the hop user in at least one way: he or she will have enough fuel to get OUT of the trouble he or she gets into after bumping into a rogue planet's gravity well.

 

[aramis]

It's worth noting that, per T5, the hop 1 cannot do less than 9 Pc nor more than 10, but only uses 1% of the ship in fuel, and takes 1 day.

Essentially, this puts commerce at 2 days + reset time (which, if unchanged, is about 4 hours), and 2% of ship in fuel. We've thus added 8% of hull in cargo to a minimal trader, given it J1-J20 (because you can triangle with two hops to any place less than 20 Pc away) at 3.5x the rate of a J1 to J3 ship. Not to mention the reduction in fuel for AM PP...

And for 9-10Pc "Nodes", you get much faster still.

Now, assuming that the drive is the same size as a jump drive of same rating (implied by the wording "The Hop Drive is an order-of-magnitude enhancement of the Jump Drive" on p. 321), we're looking at a ship going from 785 tons to 875 tons of cargo on a 1 KTd, and going from 2-3 trips per month to 10 trips per month.

Note: There's no reason to switch a civil ship in T5 over to AM from fusion; the tonnage lost in fuel makes up for tonnage gained in drive size and availability of fuel.

 

[atpollard]

Oort and Hill clouds are interesting, but will Hop-Skip-Jump drives really matter?

Does T5 intend to push the OTU TL into the anti-matter, disintegration, shields range?

And I have some issues with the whole minimum jump.
Jumping 9 parsecs away and 9 parsecs back to travel 2 parsecs just seems odd.
If coupled with all of the other Star Trek-like Tech, it sounds like a head-scratch moment in the making.

Does T5 offer insight on how this stuff is intended to fit in?
I can't see the big picture from the details presented so far.

[I am not trolling for a fight or even being over critical of T5. I am just wondering if someone else 'get's it' and can explain it to me.]

 

[mike wightman]

Yes, the hop drive can do lesser jumps, it can even make insystem jumps. All you have to do is aim your hop line so that an object's 100d limit interrupts the hop.

For short hops you actually want stuff to be in the way

 

[aramis]

Oort and Hill clouds are interesting, but will Hop-Skip-Jump drives really matter?

Does T5 intend to push the OTU TL into the anti-matter, disintegration, shields range?

And I have some issues with the whole minimum jump.
Jumping 9 parsecs away and 9 parsecs back to travel 2 parsecs just seems odd.
If coupled with all of the other Star Trek-like Tech, it sounds like a head-scratch moment in the making.

Does T5 offer insight on how this stuff is intended to fit in?
I can't see the big picture from the details presented so far.

[I am not trolling for a fight or even being over critical of T5. I am just wondering if someone else 'get's it' and can explain it to me.]

I can extrapolate a bigger picture, but I'm not certain it matches the one Marc intends.

Hop, the moment it becomes practical (early, rather than experimental - circa TL15, by the letter of the rules) can displace jump. Even allowing for the doubles... instead of the potential for singles as with Robject's suggestion...

Hop drive pretty much replaces jump drive for commerce as you get more tonnage open for cargo, use less fuel, and get there faster. That triumvirate spells the end of commercial jump drive in the same way that the jeep and deuce-and-half replaced horse drawn wagons. Or that oil boilers replaced the last commercial sail. (Think of coal as J5 or so... yeah, much faster than sail, but so much more expensive, but oil, while more expensive than sail, was enough faster to make up for on time costs what it loses on fuel and hardware.)

Using Robject's ≤9Pc Fudge, jump will disappear within 40 years as a commercial concern, unless hop is more than 4x more expensive. And, on scheduled routes, it would need to be 15x more expensive.

Minor worlds will be even more marginalized; major worlds under jump will become the second and first tiers, as they are now just so much closer.

A few jump 1-3 lines will remain amongst the smaller mains, one with worlds too low value to be worth the effort to connect with a hop, and too low tech to build it themselves.

AM drives under T5 more than make up for the gains in fuel with losses in plant size.

 

[whulorigan]

Hop, the moment it becomes practical (early, rather than experimental - circa TL15, by the letter of the rules) can displace jump.

I believe the Early Hop Drive would appear at TL16, since Standard Hop is a TL-17 development *, and "Early" technology normally appears one TL before the Standard version.

* Note thought that there is a potential errata item here, as there is at least one reference in the T5 text to Standard Hop-Drive being a TL-18 development.
​

 

[Carlobrand]

Yes, the hop drive can do lesser jumps, it can even make insystem jumps. All you have to do is aim your hop line so that an object's 100d limit interrupts the hop. ...

I thought I was doing this in the first place, using the target world's 100d limit to precipitate from jump so I exit as close to the target world as possible. I take from this that the hop drive's 9 parsec minimum is only theoretical, since in practice anyone wanting to hop closer will just navigate to intersect the target world's 100d limit, or at worst the target star's 100d limit.

 

[aramis]

I believe the Early Hop Drive would appear at TL16, since Standard Hop is a TL-17 development *, and "Early" technology normally appears one TL before the Standard version.

* Note thought that there is a potential errata item here, as there is at least one reference in the T5 text to Standard Hop-Drive being a TL-18 development.
​

T5 allows up to 3 TL early for experimental.
Prototype is 2 TL below

The 2 TL prior is only 5x cost and 1.2x fuel used, and 1.25x drive size (=80% Efficiency)

 

[whulorigan]

Hop, the moment it becomes practical (early, rather than experimental - circa TL15, by the letter of the rules) can displace jump.

T5 allows up to 3 TL early for experimental.
Prototype is 2 TL below

The 2 TL prior is only 5x cost and 1.2x fuel used, and 1.25x drive size (=80% Efficiency)

Yes, but in your initial quote above (bolded) I had thought you were specifically referring to the "Early" Drive, which is at TL minus 1. If Standard Hop is TL-17, then an Early Hop Drive would be TL-16, just as a Prototype Hop Drive would be TL-15 and an Experimental Hop Dive would be TL-14. In my mind, the "Early" version of the drive is the first practical version (albeit in limited use), the Prototype & Experimental versions being relegated to research laboratories and testing facilities. So a universe operating on a "Hop-based" paradigm would not show up before TL-16 at the earliest.

Perhaps I have misunderstood what you were trying to communicate?

 

[whulorigan]

Does T5 intend to push the OTU TL into the anti-matter, disintegration, shields range?

I think the information is there for three reasons:

1) For GMs who are running their own ATUs at higher TL;

2) For modelling the Ancients (and Old Darrian, Sabmiqys, et al) Technology;

3) For use in the OTU of the future relative to all of the canonical OTU history that has been written to date (i.e. Technology that will be discovered at some time post-Imperial Year 1250 - perhaps centuries later). Remember, the Galaxiad Era is supposed to take place ca Imperial Year 1900.
​

 

[robject]

I believe the Early Hop Drive would appear at TL16, since Standard Hop is a TL-17 development *, and "Early" technology normally appears one TL before the Standard version.

* Note thought that there is a potential errata item here, as there is at least one reference in the T5 text to Standard Hop-Drive being a TL-18 development.
​

Drive efficiency is too low in pre-Standard versions to be useful. Which is why there are no Jump drives on the market at TL 8 (for example).

Antimatter, when it becomes available, isn't as suitable for small starships, due to a 30t overhead, but if you've got 30+ tons of fuel, then antimatter is a good idea.

 

[rancke]

Drive efficiency is too low in pre-Standard versions to be useful. Which is why there are no Jump drives on the market at TL 8 (for example).

Antimatter, when it becomes available, isn't as suitable for small starships, due to a 30t overhead, but is useful for ships 1000+ tons.

So did the Darrians have hop drives in the revised OTU? They were solid TL16 and were edging into TL17.

I'd have to think about it a bit, but I think I would like to revise Lon Geryen, my IA controlled Darrian scout ship that was the last ship ever built by the Old Darrians, and furnish it with a hop drive, but only if it would be useful. Perhaps both a J6 drive and an experimental Hop 1 drive (that turns out to work unexpectedly well, just like a regular Hop 1 drive)?


Hans

 

[whulorigan]

So did the Darrians have hop drives in the revised OTU? They were solid TL16 and were edging into TL17.

I'd have to think about it a bit, but I think I would like to revise Lon Geryen, my IA controlled Darrian scout ship that was the last ship ever built by the Old Darrians, and furnish it with a hop drive, but only if it would be useful. Perhaps both a J6 drive and axperimental Hop 1 drive (that turns out to work unexpectedly well, just like a regular Hop 1 drive)?

Actually, using T5 RAW, an Old Darrian TL-16/17 vessel could theoretically have a Jump-7 (or maybe Early Jump-8) Drive as well.

 

[Aramais]

WORKING Hop Drives

Actually, using T5 RAW, an Old Darrian TL-16/17 vessel could theoretically have a Jump-7 (or maybe Early Jump-8) Drive as well.

One can safely say that the Pre-1250 OTU will not be rewritten with Hop Drive. It is safe to say that the Darrians were working on the theoretical bases of Hop Drive at some point, but never realized a fully functional, efficient and controllable Hop Drive. A prototype sort-of worked once at the Darrian high point, but the vessel never returned to known Darrian Space. See Cirque for details (Cirque is canon in MY mind, but I may be delusional).