What do astrogators & engineers do? And, Fleet jumps

[DFW]

Please read my OP in this thread 1st: http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=48084

What do astrogators do?

As we know from jump shadows and precipitating out of J-space when coming within 100D of a large enough mass, jump space corrosponds to our space. This requires "line of sight" calculations from jump entry point to exit point to ensure no intervening bodies exist onlong the "flight path". In addition, the anti-matter distibution in J-space isn't 100% uniform. It appears to be influenced by the presence and movment of masses in our space. This is important as the Hydrogen interacts with the anti-matter, through the J-bubble energy barrier, to produce energy that directs and helps propel the ship through J-space. So, variations in the density can effect time in jump (see J-time variable) and vector (see jump accuracy results). There is also local variablility in the "thickness" of space between the two "sides" (see my 1st thread above). This variablility is caused by the ripple effect on space itself by the local system planet's rotation and movement through space. http://www.space.com/11570-nasa-gravity-probe-einstein-theory-relativity.html This effects the of power adjustment and configuration of the Jump bubble that the J-Drive needs to create when the ship enters Jump space. So, the astrogator, using the computer, takes all known, somewhat known & best guess data (local space conditions, destination system data, space along "flight path" & anti-matter density in J-space) to create a jump plot.


Because of the above, the Astrogator can sustitute skill level In Physics or, (if YTU supports, Astro-physics) in place of the EDU characteristic bonus, to the skill roll mod. (specific, relevant education being more valuable than general EDU in this case). In MTU, one must have an EDU of 8+ to train as an Astrogator.

Even though the Astrogator check is a go, no go, roll (modified 8 or better or no usable calc), the degree of success (effect) does modify the Engineers skill check. Here's how; The the two tasks ARE "chained". Use the Task Chain DM's. N.B. There is never a negative effect DM from the Astrogation check.

As per the rules, astrogation calculations can be done ahead of time. This is because the data as to where the ship will be, when, and where all the relevant masses in space will be, can be known. There are two somewhat unknown variables. The precise local space conditions as effected by the local "ripple" effect at time of jump (see space.com link above) and, variability of anti-matter distribution in J-space along the entire route.

There IS a way to refine the final "effect" of the astrogation check based on local space conditions. The use of a Densitometer sensor, once the ship is at the jump point, adds 2 to the final effect value.

This modifier is NOT added to the roll to determine success (8+ calc) but is added to the result to determine effect value. Example: After DM's, the Astrogator's check total is 9. (succesful Jump calc) To this is added 2 for a total of 11 (Average Success) and a +1 to the Task Chain DM that the Jump Engineer adds to his roll. If the Astrogator's check is <8, it is a no go and, the Densitometer doesn't help.

Densitometers are only sensitive enough to detect these slight variations in space out to 1/100th of a light second (3000km). This figure is important, as you will see later.

So, the Astrogator generates the "what" & "when" data. Now, the Jump Engineer takes that and figures out the "how", vis-a-vis the Jump Drive operation.

Based on the Astro's calculations & data, the Engineer programs the exact amount of energy, the shape and field strength of the "bubble", how fast the energy is released from the Jump capacitors and at what rate the Hydrogen is introduced to form the "bubble". After that is done, the computer adds in the non-variable data of the J-Drive model, ship hull size & shape. The J-Drive Engineer then pushes the "Go" button. There is no turning back.

Multi-ship coordinated jumps:

In order to perform this action, three things are needed that are not required for a normal jump.

1: Densitometer in command ship.
2: Additional s/w for Astorgation calc pgm. used by the "Fleet Astrogator".
3: Add on Jump Drive s/w used by the "Fleet J-Engineer" and the other ships.

This s/w doesn't increase the computer size needed on any of the ships.

Procedure:

The Fleet Astrogator, while calculating the jump, issues fleet placement positioning orders within a radius of 3000km from the command ship. (see Densitometer range limitations above). All participating ships must be within this spherical area.

The Astrogator passes completed calcs to Fleet Engineer who does all calcs except for final, non-variable data (see above) and sends this data to other ship's J-Drive Engineers, along with the exact Jump Drive engagement time.

The other ship J-Drive Engineer's enter the calculated data and add in their ship's non-variable data and input the predetermined time (to the mili-second). When the time arrives, the J-Drive s/w automatically activates the drive.

For better or worse, all the ships use the Fleet Astrogator's & Engineer's skill check results. They jump as one ship.

 

[locarno24]

The Astrogator passes completed calcs to Fleet Engineer who does all calcs except for final, non-variable data (see above) and sends this data to other ship's J-Drive Engineers, along with the exact Jump Drive engagement time.

The other ship J-Drive Engineer's enter the calculated data and add in their ship's non-variable data and input the predetermined time (to the mili-second). When the time arrives, the J-Drive s/w automatically activates the drive.

That, by itself, is going to partially limit effective range even if you were prepared to risk a jump without a densitometer sweep - I'd have thought that co-ordinating exactly to the millisecond starts to become noticably more difficult once operating at light-time ranges greater than that.

 

[DFW]

I'd have thought that co-ordinating exactly to the millisecond starts to become noticably more difficult once operating at light-time ranges greater than that.

Not at all. We can do better than that now. I don't see it as a problem 5 TL's higher than today's. All it takes is accurate time on each ship. After that, the range doesn't really matter.

 

[locarno24]

Provided they're all leaving from a common base, I guess.

 

[DFW]

Provided they're all leaving from a common base, I guess.

Not at all. There is no problem synchronizing while in space. GPS satellite time is accurate to about 14 nanoseconds. Any ship (command ship in this case) acts as the time setter.

 

[alex_greene]

I think someone once responded to one of my posts on astrogation along the lines of "They push a button, course laid in, job done."

 

[SSWarlock]

They push a button, course laid in, job done.

If that's what they wanted in their TU, cool. But it then seems that there would not be a real need for a navigator or the skill. Why not just have the pilot push the button?

 

[BFalcon]

I think someone once responded to one of my posts on astrogation along the lines of "They push a button, course laid in, job done."

I think that's probably true a lot of the time with a decent jump computer, but there's always the chance that you need to do a "best guess" jump because of speed required (ie "we jump now, or we die... your call!") or the nav computer's on the blink again and no time to repair it, so all that knowledge the Astrogator's got in his head suddenly comes into play as he needs to do it by hand (probably using non-specialised computers, his own spreadsheets and having to manually check the navigation charts as best he can).

It's always worth, IMO, paying the extra for that 1 in a million chance that you'll need something than to rely on computers that can go (horribly) wrong sometimes.

 

[rust]

... so all that knowledge the Astrogator's got in his head ...

... could just as well be in the pilot's head, especially since otherwise his
only truly job related skill would be Pilot.

And if the pilot comes from the Scouts, he has had to learn Astrogation
anyway, while all other typical pilot careers and skill packages at least
make it easy for him to learn Astrogation, too. On the other hand, it is
slightly difficult to learn Astrogation skill without learning Pilot skill, too,
there is no real Astrogator career anywhere in the books.

In the end Traveller's typical astrogator turns out to be just another pi-
lot, like the co-pilot on modern airliners, and since starship crews often
have to work shifts, two pilots with Astrogation skill for the watches ma-
ke a lot more sense than a pilot without Astrogration skill and an astro-
gator without Pilot skill.

 

[BFalcon]

... so all that knowledge the Astrogator's got in his head ...

... could just as well be in the pilot's head, especially since otherwise his
only truly job related skill would be Pilot.

And if the pilot comes from the Scouts, he has had to learn Astrogation
anyway, while all other typical pilot careers and skill packages at least
make it easy for him to learn Astrogation, too. On the other hand, it is
slightly difficult to learn Astrogation skill without learning Pilot skill, too,
there is no real Astrogator career anywhere in the books.

True under ideal circumstances... but would you really want to trust a jump plotted by a pilot who had to dodge incoming fire while he did it? I wouldn't even trust a plot done by a pilot who was only monitoring the readouts on the consoles... navigation in 2D is hard enough when moving at high speeds (I had to do airborne navigation in the cadets - fun when you're going a mile every few seconds... imagine going 100's of times that...) but in 3D over lightyears of distance, having to use last-known trajectories and positions of all stellar objects and then extrapolate their positions using a computer in order to make sure you don't misplace a planet on the destination system (or any system you need to pass through the outskirts of, potentially)...

To quote (kinda): "Plotting a jump ain't like dusting crops boy..."

The last thing you want to do is end up misjumping into a system without a fuel source having pumped all your jump fuel into the jump to your intended target - just because you miscalculated the position of a planet in the interceding system... After all, a planet's orbit is just empty space (insofar as any space is) when the planet's not there...

 

[BFalcon]

And on your co-pilot theory, I fully agree... except it might be like the bombers in WWII where the navigator needs specialist equipment, so is housed behind the cockpit occasionally, so cannot function as a pilot while he's doing his astrogation duties...

In fact, it IS possible to be able to navigate without being able to fly to a level where you'd qualify as a pilot, just as you might be able to fly without being able to (manually) navigate...

A single-seater fighter relies on electronics and waypoints that are pre-set to free up the pilot for his duties as a pilot. A twin-seater usually relies on the RIO to worry about where they are (at least on some aircraft) and because the RIO has no piloting duties can concentrate on his navigation if need be. So a pilot who learned in a fighter may have zero navigation skills (in the space sims I've played, you usually get a computer generated symbol on the HUD showing where to aim to be on-course... I can't see it being much different in Traveller in some instances).

 

[rust]

True under ideal circumstances... but would you really want to trust a jump plotted by a pilot who had to dodge incoming fire while he did it?

If the pilot is no fool, he will have an idea where he intends to go and what
the most likely alternatives will be, and will have those jumps calculated
and stored in the computer, so all he has to do for the actual jump is to
push the proverbial button.

 

[BFalcon]

True under ideal circumstances... but would you really want to trust a jump plotted by a pilot who had to dodge incoming fire while he did it?

If the pilot is no fool, he will have an idea where he intends to go and what
the most likely alternatives will be, and will have those jumps calculated
and stored in the computer, so all he has to do for the actual jump is to
push the proverbial button.

True, but evasive maneuvers might cause those calculations to be thrown out - for example, the previous course might now take you within 100d of a planet in your system that you would otherwise have missed if you'd used your planned jump... likewise being an few hours earlier or later might have the same effect. Your case is spot on for ideal circumstances, but (particularly in military or high-value cargo vessels) organisations sometimes prefer to have a specialist do the job.

 

[DFW]

and will have those jumps calculated
and stored in the computer, so all he has to do for the actual jump is to
push the proverbial button.

Actually, for a simple J-2, an astrogator-1, spending an average of 30 minutes only has ~50% chance of being able come up with a correct plot using known data... So, the "push the proverbial button", can't be done.

 

[rust]

Actually, for a simple J-2, an astrogator-1, spending an average of 30 minutes only has ~50% chance of being able come up with a correct plot using known data... So, the "push the proverbial button", can't be done.

Since astrogation can be done in advance, the astrogator obviously has
a way to know whether his calculations were right before the actual jump,
so when his first attempt was a fumble, he has to make another one be-
fore he can store the result in the computer - and then still push the pro-
verbial button at the time of the actual jump.

The alternative would be that only the jump itself is "the proof of the pud-
ding", and the astrogator only realizes that his calculations were wrong
at the moment of the actual jump, when the ship either does not jump
or misjumps - but this is nowhere in the rules, the astrogation has no in-
fluence on the actual jump roll (which I find rather strange).

 

[DFW]

Since astrogation can be done in advance, the astrogator obviously has
a way to know whether his calculations were right before the actual jump,
so when his first attempt was a fumble, he has to make another one be-
fore he can store the result in the computer - and then still push the pro-
verbial button at the time of the actual jump.

Not quite. Per the rules you can do it in "advance" in the time frame of heading to the 100D limit. There is no "store for many systems and use whenever"... Too many constantly changing variables.

 

[phavoc]

One could also conceivably purchase a jump navigation program prior to departing port. Proceed to point X and push the button. No navigation skill required.

Though this would not work in the wilds, or where sophisticated navigation equipment and sensors were not already available. But for travel between high TL worlds, it would be easy to implement.

 

[DFW]

One could also conceivably purchase a jump navigation program prior to departing port. Proceed to point X and push the button. No navigation skill required.

Not according to the MGT RAW.

 

[BFalcon]

Well, to be honest, although a lot can be worked out in advance, the jump computer is probably working from reference data and extrapolating the current positions (and hence gravitic spheres of influence), including deflection due to spheres of influence overlapping. It then needs to work out precisely how much fuel to use and the precise bearing needed to achieve the precise position desired. A single error in this process will end up in a misjump.

Ordinarily, all the astrogator would do is operate the navigation side of the jump computer, while the other side - the physical side - would be automated to a large degree, but the Engineer would be monitoring it.

I guess a good (but far less dangerous) analogy would be driving a car while trying to read a map - but off-road, so you only really need to worry about random rocks or similar in your way... better to have someone dedicated to the job in-back while your co-driver is up front helping to look for routes through the terrain and trying to keep an eye on the compass to make sure you don't stray off course too far... usually you could use the GPS, but a GPS is only good as long as the batteries last or it doesn't crash... and there's a minefield marked on the map which you REALLY don't want to stray into...

Would you still rely on the GPS? Or would you want those two guys to be backing it up or just riding along looking at the scenery?

As for knowing when he got it wrong... I think you'd know if it was wildly out (ie you had 1/3 of the fuel requirements or suddenly noticed the wild rogue moon that you'd overlooked before or just been told about over the comms network) but the truth will only really be known when you jump - that's how and why (I think) the misjumps happen - badly calculated or misinformed navigation, polluted fuel and so on... in other words the wrong fuel quantity or the wrong course.

But I'm not convinced about doing the course too early on the 100d trek, depending on how long it will take - updates are probably broadcast constantly in populated systems as new ships enter the system, so the astrogator would probably want to plot his course as late as possible to help to prevent a misjump.

 

[BFalcon]

One could also conceivably purchase a jump navigation program prior to departing port. Proceed to point X and push the button. No navigation skill required.

Though this would not work in the wilds, or where sophisticated navigation equipment and sensors were not already available. But for travel between high TL worlds, it would be easy to implement.

3

Hehe you really want more expense??

I doubt that would happen, to be honest - Rust is right that the majority of pilots would have at least competancy level in astrogation, but the larger ships would employ a specialist (after all, who wants their cargo or a few hundred passengers dissapearing when they're relying on a member of staff who's less than perfectly qualified). There's also the question: Would you trust a product sold to you that you don't know who wrote it and also that you can't get your money back on? After all, any customer who's less than satisfied would probably be stranded in the middle of nowhere or might be spiralling into a star...

People tend not to trust anyone who is out to make a profit where customer safety is concerned, unless they can verify the safety of it... which would be impossible, given the size of the Imperium...