Artificial Gravity on JumpShips

[Achtung Minen!]

I always wondered this... JumpShips usually have grav decks to simulate gravity in space: essentially a ring that spins in the middle of the JumpShip. But why doesn't the entire ship just spin? Presuming the diameter of the ship is sufficient to produce the effect of gravity for the grav deck, it seems that it would be effortless to do the same for the entire ship, using small maneuvering thrusters on the outer hull to begin the rotation.

Granted, this would raise difficulties when the JumpShip either wanted to maneuver or dock with dropships, but given that JumpShips usually appear hundreds of thousands of kilometers away from planets and dropships have to travel for days from the jump points to the planet, it seems like there is a lot of downtime where the JumpShip is just waiting in deep space for the dropships to return.

Also, isn't the radius of a JumpShip (and thus also its grav deck) a little small to reproduce the effect of gravity in the first place (according to real-world physics)?

[Tai Dai Cultist]

It'd require dropships to unhitch if the JumpShip wanted to simulate gravity. Granted, it doesn't matter if all the DSs are in transit, but it is a bigger deal while recharging between jumps.  And besides, in commercial applications a JumpShip is more like a city bus than an airliner... normally passengers get onboard in a piecemeal manner rather than everybody on all at once and everyone off all at once.

As for the small size of JS gravdecks: they'd have to spin at nausea-inducing speed to achieve 1g... so they spin slower and generate lower gravity.  1/2 or even 1/3 standard gravity is enough to allow for more comfort and health than microgravity.

[Knightmare]

IIRC Grav Deck orientation to the ship's decks/spine are perpendicular to each other.

BattleTech JumpShips are built like skyscrapers, so the nose of the ship is actually "up." This way, when the ship's maneuvering, station-keeping or transit drive is fired the thrust creates artificial gravity. During active thrust, the Grav Deck is locked and non-rotating.

However, when then JumpShip or WarShip is in micro-gravity or not under thrust the Grav Deck can spin up, creating gravity via centrifugal force. Meaning, as the ring spins the outer portion of the deck becomes the floor, and the center of the deck—which is likely the ship's spine—becomes the deck's roof.

The point being, sending a ship into thrust while spinning a grav deck places the gravitational pull from the thrust horizontal across the grav deck.

Now, think of the grav deck as the whole ship, but with the drive still oriented along the ship's spine...messy. And JumpShips still need a station-keeping, maneuvering drive. They may not produce a ton of thrust at once, but they can still move a great distance if need be.

[ActionButler]

This is less of an Inner Sphere question than it is an Aerospace question, so we are moving it to the Aerospace sub-forum.
Carry on, all!

[Cryhavok101]

I have always wondered how valuable velcro was in battletech, with systems like that that regularly alter the orientation of gravity in an area, interspersed with areas of periodic micro/zero gravity.

[Knightmare]

96.7% sure I've read novels where the use of velco shoes, or something similar was used to maintain posture in low-micro gravity.

Although, I could be thinking of another setting...::shrugs::

I wonder if silent velcro is a real thing in the BTU?

[cray]

IIRC Grav Deck orientation to the ship's decks/spine are perpendicular to each other.

Gravdecks should circle the spine/KF core. It's the easiest orientation to handle stationkeeping thrust. If you use more than a milli-G of thrust, you can just shape the grav deck like a cone to absorb the combined translation/spin acceleration vectors into a single acceleration vector perpendicular to the tilted deck. It's how the gravdecks on low-G worlds like Luna are arranged.

BattleTech JumpShips are built like skyscrapers, so the nose of the ship is actually "up."

To answer the OP's question, this is a key point. Even JumpShips may be expected to accelerate at 0.1G on the rare times they cross a solar system for some reason. Arranging the decks for spin gravity makes these relatively slow transits into weeks of misery.

Another key point is that JumpShip crews are small compared to the volume of the ship. A 100-meter diameter gravdeck is a 314m length of space that could easily hold individual rooms for hundreds of people plus recreational, dining, and hygiene facilities. JumpShips have much smaller crews than that, so you end up with a lot of unused volume in even small gravdecks, never mind the entirety of the ship.

Further, docking collars aren't strong enough to DropShips under acceleration. You'd have to de-spin those from the rest of the ship.

[worktroll]

Wouldn't there also be issues with spinning a DropShip on its axis fast enough to generate useful pseudo-G, given their smaller diameters?

Cray signal lit! What's the amount of spin we humans can cope with before nausea sets in? And the differential spin rates between head & feet that produce similar issues?

[cray]

Cray signal lit! What's the amount of spin we humans can cope with before nausea sets in?

Per pg140 StratOps, you want to stay below 3rpm. NASA studies have found that 1 to 3rpm (maybe 4) isn't too bad on the inner ear and most people can adapt (key word: adapt). Above 3rpm and any movement of the head in that environment can be disorienting, though people who keep their heads stationary shouldn't have an issue - you can experience it yourself on high-speed spinning rides like "Gravitron" or Epcot's "Mission: Space." Below 1rpm and the spin isn't very noticeable to the inner ear.

If you're aiming for 1G, you get 1G at 1rpm at about 1800m diameter. 2rpm allows a 450m diameter grav deck, while 3rpm can be 200m. Most DropShip-scale spinning grav decks need to accept lower acceleration or risk nauseating their occupants.

And the differential spin rates between head & feet that produce similar issues?

I didn't think there'd be a big issue, assuming the peak G-force is only about 1G at the feet. Do you have a link or example of the effects of this?

[worktroll]

I'll look - I think it only tends to come into effect when height is a major fraction of the spin radius.

(Imagine 1.8m person standing in a 1.8m radius hamster wheel ...)

[cray]

I'll look - I think it only tends to come into effect when height is a major fraction of the spin radius.

(Imagine 1.8m person standing in a 1.8m radius hamster wheel ...)

That might be less troublesome than standing on your head on a 1G planet. On the planet, you have uniform gravity puddling blood in your head. Under spin across a 1.8m radius, you have centripetal force in the legs and mid-body fighting that tendency.

But spin gravity's weird. A good paper to the contrary would be interesting reading.

[Cryhavok101]

96.7% sure I've read novels where the use of velco shoes, or something similar was used to maintain posture in low-micro gravity.

Although, I could be thinking of another setting...::shrugs::

I wonder if silent velcro is a real thing in the BTU?

2001 space odessey used velcro for zero-g IIRC, and I think NASA uses it. No idea if it appears in any battletech novels.

[cray]

2001 space odessey used velcro for zero-g IIRC, and I think NASA uses it. No idea if it appears in any battletech novels.

NASA / ISS uses velcro to secure small items. Skylab used a system of locking cleats on an open gridwork floor; the ISS uses numerous restraint and mobility aids, but experience has found velcro shoes and magnetic boots aren't worth it. Some BattleCorps stories have mentioned magnetic shoes, but p. 256 StratOps addresses those and magnetic boots:

For spacers who can’t find a convenient freefall handhold or
foothold or other anchor, there are Velcro and magnetic shoes.
These are options of last resort. While cheap vid directors like to
use “magnetic shoes” as an excuse not to record their tripe in actual
freefall conditions (like Danger Dave), such shoes actually offer
little advantage. They’re basically good for holding you in place.
Trying to simulate walking in 1 G with a magnetic field around
your foot verges on folly because when you walk in gravity, your
moving foot does not have the weight of your body over it—
you put your weight on the stationary foot. Having to lift a foot
against magnetic or some other retaining force that approaches
full bodyweight is unnatural. The reality is that the experience of
simulating full bodyweight through such shoes or boots is like
fl oating underwater with heavily weighted shoes. You get to float
around like a waving seaweed anchored to the ocean floor.

[Cryhavok101]

NASA / ISS uses velcro to secure small items. Skylab used a system of locking cleats on an open gridwork floor; the ISS uses numerous restraint and mobility aids, but experience has found velcro shoes and magnetic boots aren't worth it. Some BattleCorps stories have mentioned magnetic shoes, but p. 256 StratOps addresses those and magnetic boots:

Oh, thanks for the reference. Yeah, I was talking about securing items, not for pretending to walk normally in zero-g lol. Having played with velcro walls/suits before, I know it would suck a lot. I do wonder how well it would work to secure larger cargo in zero-g though.

[cray]

Oh, thanks for the reference. Yeah, I was talking about securing items, not for pretending to walk normally in zero-g lol. Having played with velcro walls/suits before, I know it would suck a lot. I do wonder how well it would work to secure larger cargo in zero-g though.

The ISS uses bungies and nylon straps.

[Cryhavok101]

It's probably easier to undo those when you want to move the cargo lol. Anyway, enough of me derailing the thread with my idyll musings.

[Weirdo]

The ISS also uses smaller images. Yikes!

[Kovax]

It might make sense for individual "rooms" along a grav deck to be able to rotate slightly (perhaps 10-15 degrees at most) to accommodate thrust from the main engines.  At rest, the rooms would all remain "level" with the structure of the deck, but under thrust, they'd tilt slightly.  That would maintain level floors, things wouldn't roll off tables, and the wall wouldn't become the floor on short notice.  The rotating couplings between rooms and the access tubes leading to the rim would be the only areas where you'd notice the change in the direction of "pull".

[SethsMatches]

Would spinning the JS also mess with the jumpsail? Would the sails inertia cause it to, rotationally, fall behind a spinning JS and start twisting?

[Cryhavok101]

Would spinning the JS also mess with the jumpsail? Would the sails inertia cause it to, rotationally, fall behind a spinning JS and start twisting?

I was under the impression that jumpships don't expend thrust at all while the jump sail is deployed, I don't see why spinning instead of expending thrust would be any different that way.

[Knightmare]

I was under the impression that jumpships don't expend thrust at all while the jump sail is deployed, I don't see why spinning instead of expending thrust would be any different that way.

Not sure that's 100%. I would imagine maintaining the sail's position to the system's primary would require some expenditure of thrust. While Jump Points aren't exactly close to a star's gravity well, objects will still move.

[Weirdo]

They only expend station-keeping thrust, which is just enough to keep them stationary against the star's gravity at that distance.

[Fireangel]

A 100-meter diameter gravdeck is a 314m length of space that could easily hold individual rooms for hundreds of people plus recreational, dining, and hygiene facilities. JumpShips have much smaller crews than that, so you end up with a lot of unused volume in even small gravdecks, never mind the entirety of the ship.

And this does not even address the width of the gravdeck... or concentric decks on the same ring.

As a 'rule of thumb', about how wide is a plain-vanilla gravdeck?

[cray]

I was under the impression that jumpships don't expend thrust at all while the jump sail is deployed, I don't see why spinning instead of expending thrust would be any different that way.

Yes, they do use thrust with the sail deployed. The sail is most often used at standard jump points, which are stationary with respect to the star and thus subject to gravity. To avoid falling (slowly) into the star, JumpShips use their stationkeeping engines, which necessarily fires through the dangling sail. (No, light pressure is not stronger than gravity at the jump points.)

And this does not even address the width of the gravdeck... or concentric decks on the same ring.

As a 'rule of thumb', about how wide is a plain-vanilla gravdeck?

No idea, but they don't have a lot of equipment or crew to support usually so they don't need to be wide. StratOps p. 140 gives an example of 10m for a 100m diameter gravdeck. p. 136 shows the Olympus with a wide-profile gravdeck that might be 200-ish meters for a 1200m diameter.

[marauder648]

With warships grav-decks it seems that they are more like tubes, they'll be X meters wide and then take up internal space rather than being a ring on the ships hull.  How this would work on ships with multiple grav decks is beyond me.

[cray]

With warships grav-decks it seems that they are more like tubes, they'll be X meters wide and then take up internal space rather than being a ring on the ships hull.  How this would work on ships with multiple grav decks is beyond me.

No, they're rings but without spokes. Like a subway train running in a circle. See StratOps p. 140.

[Kovax]

Obviously, there need to be at least one or two "spokes" (or access tubes) to connect the grav deck to the ship, unless the ship's own outside diameter is large enough to extend out to the inner rim of the grav deck.  That can be done by making a pancaked jumpship design, turning it into a disc (with the grav deck on the outer rim) skewered by a stick (the jump core), rather than a spoked wheel on a stick.

From a practicality perspective, having a grav deck with a central corridor and rooms on either side would seem to be the obvious solution.  That gives us a 1.5-3 meter practical minimum width (1-2 meters for the passageway, and another half-meter plus of walls, armor protection, and equipment) where there are no rooms, and something like 10+ meters width wherever there are rooms.

[Weirdo]

...unless the ship's own outside diameter is large enough to extend out to the inner rim of the grav deck.

That is already the case with the vast majority of spacecraft, or at least those that actually use grav decks. Aside from the Wagon Wheel, all ships are big enough(or the grav deck small enough) that the entire grav deck mechanism is completely within the ship's main hull.

[Wrangler]

Would spinning grav decks on real life cause a real life ship need fuel to keep. The ship on course?
I remember reading some where its a problem.

[cray]

Obviously, there need to be at least one or two "spokes" (or access tubes) to connect the grav deck to the ship,

Gravdecks are fully contained in ships, so there are other options than spokes like tracks paralleling the gravdeck with small transfer cars. Per p. 140 StratOps:

A space station can be built to almost any geometry with no concern for
a K-F drive core, ammunition feeds, power lines, data cables or
anything else that must run through the center of a JumpShip or
WarShip. ... Space station gravdecks therefore can
be built with simple systems for transferring people to and from
them, such as long elevator spokes to a slow-spinning hub.
JumpShips and WarShips generally cannot spare the volume or
passage room for such elevator spokes and must use “subway”
systems of transfer cars paralleling the gravdeck’s track.

This complete internal containment is why JumpShips tend to have tiny ( <100m diameter) gravdecks. Only the Wagonwheel puts its gravdecks visibly outside the hull.

Would spinning grav decks on real life cause a real life ship need fuel to keep. The ship on course?
I remember reading some where its a problem.

The gravdeck isn't used at more than stationkeeping thrust so gyroscopic precession wouldn't be a problem. However, if you find a ship that uses high acceleration and gravdecks, there are a number of options. For example, you could include a massive flywheel that spins in the opposite direction of the gravdeck to counter the precession. Alternately, you could include two gravdecks of equal size and spin in opposite directions.

[VhenRa]

Only the Wagonwheel puts its gravdecks visibly outside the hull.

Not entirely true. Concordat, New Syrtis, Dreadnought and possibly some of those from the 2765 Field Reports have visible gravdecks.

Also have some of the largest grav-decks in setting.

[Weirdo]

Visible, but still fully enclosed. Those ships can use the space inside the ring for anything the designers want(cargo, quarters...okay, maybe not guns), while the Wagon Wheel has simply support spokes and empty vacuum.

[idea weenie]

Not sure that's 100%. I would imagine maintaining the sail's position to the system's primary would require some expenditure of thrust. While Jump Points aren't exactly close to a star's gravity well, objects will still move.

If the area of the sail is large enough vs the sail's mass being attracted by the star's gravity, it could be 'pushed' back at a similar rate as the star's gravity is pulling it towards the sun, effectively canceling each other out.

[cray]

If the area of the sail is large enough vs the sail's mass being attracted by the star's gravity, it could be 'pushed' back at a similar rate as the star's gravity is pulling it towards the sun, effectively canceling each other out.

No solar sail in BT produces enough thrust from light pressure to lift itself against stellar gravity, let alone the entire ship. The gap is about a factor of one hundred for the solar sail alone, if I recall correctly the last time I ran the calculations.

There is a completely different "light sail" for satellites that will hold a satellite at a jump point, but it isn't available for larger vessels and should not be confused with the "solar sail" aka "jump sail."

[Cryhavok101]

I found the references that made me think ships don't move with deployed sails:

Fluff from SO pg 124:

Sails are only deployed when a JumpShip is parked at a jump point because any real acceleration will rip them apart.

It goes on to talk about the station keeping drive being used to counter the stars gravity, because as Cray said, the sail provides no propulsion, however, the effect of the station keeping drive is have no movement.

In addition, in the Advanced Battleforce rules on pg 276 of SO it says:

Furling/Unfurling Jump Sails: Prior to any maneuvering, JumpShips must furl (close) their jump sails. Reeling in a jump sail takes 350 turns. Unfurling a jump sail takes 180 turns.

And again on pg 277 of SO it says:

Detaching Jump Sails: Prior to any maneuvering or executing hyperspace jumps, WarShips must furl (close) their jump sails. Times for this are the same as for JumpShips. Additionally, WarShips may detach their jump sails. This process takes 4 turns. Reattaching a jump sail takes 12 turns and requires the WarShip to successfully dock with the jump sail first

I couldn't find any reference under standard rules about needing to not be moving around with a deployed jump sail, but hopefully this illustrates why I might think that to be the case.

(disclaimer: All quotes were taken from my PDF, which drivethruRPG tells me is up to date, I did not bother checking for any errata on the matter)

[cray]

There hasn't been an errata on moving with deployed sails.

It goes on to talk about the station keeping drive being used to counter the stars gravity, because as Cray said

Well, do note who wrote the fluff sections in StratOps on spacecraft operations. ;) My statements are just summarizing (parroting) my writing in StratOps.

[VhenRa]

You can tell who wrote a section like that.

The science to word count rises.

[idea weenie]

No solar sail in BT produces enough thrust from light pressure to lift itself against stellar gravity, let alone the entire ship. The gap is about a factor of one hundred for the solar sail alone, if I recall correctly the last time I ran the calculations.

There is a completely different "light sail" for satellites that will hold a satellite at a jump point, but it isn't available for larger vessels and should not be confused with the "solar sail" aka "jump sail."

(I had been thinking just the solar sail would use solar pressure to hold steady while the ship used station-keeping thrust, but I am wrong.)

Didn't know these.  Very good stuff here, thank you.

[vidar]

Those sciency sections are my favorites.  I like when I have to look up the word >:D

[Kovax]

Am I correct in assuming that the light sail hangs "down" toward the star, and that the hole in the center is for the station-keeping drive to fire through without damaging the sail?  If so, that pretty much verifies that light pressure from the star does not move the sail, much less the entire ship, against gravity at that distance.  Stray particles from the drive stream would also tend to push against the sail, keeping it rigidly extended in the weak gravity.

[cray]

Am I correct in assuming that the light sail hangs "down" toward the star, and that the hole in the center is for the station-keeping drive to fire through without damaging the sail?  If so, that pretty much verifies that light pressure from the star does not move the sail, much less the entire ship, against gravity at that distance.

p124 StratOps: "At a standard jump point, jump sails dangle under the JumpShip facing the star, pulled down under by their own weight. Yes, weight. The zenith and nadir points aren’t in orbit, hence the station-keeping drives that keep JumpShips from plummeting into stars. ... Solar sails offer no propulsion to speak of—they’re not real sails, and light pressure is usually much weaker than stellar gravity at standard jump points. And before you ask, the solar wind is even weaker than light pressure."

[Kovax]

Thanks, thought so, but don't have Strat Ops.

[croaker]

I believe the impression that the sail provided sufficient thrust to cause appreciative acceleration comes from the very early texts where the sail size was approximately a factor of 100x the current sizes.

[The_Caveman]

I believe the impression that the sail provided sufficient thrust to cause appreciative acceleration comes from the very early texts where the sail size was approximately a factor of 100x the current sizes.

I don't remember having ever seen a reference to 100km+ jump sails.

Sword and the Dagger, maybe? BattleDroids makes no mention of JumpShips even being a thing (DropShips were hyperspace capable at first) and by the time DropShips and JumpShips came out, sail size was fixed at the current dimensions.

[cray]

I don't remember having ever seen a reference to 100km+ jump sails.

DropShips & JumpShips and StratOps cover it, sort of. Croaker was off by a factor of 2.

DropShips & JumpShips, p. 14, has a sidebar section called, "Jump Sail." "The second major improvement [in the 22nd Century] wrought major changes to both the operational characteristics of the JumpShip and its outward appearance . This new development was the energy collecting jump sail, whose development was made possible by new polymer and advanced metallurgic technologies . The huge parasol-shaped sail was some 50 kilometers in diameter and constructed of high-strength material coated with a special energy-absorbing surface." It rapidly shrank in size as the technology advanced.

StratOps p. 124: "The advantage to sails is that they give JumpShips almost limitless endurance and greatly accelerated human colonization when they were introduced in the 2200s. The first sails were giant arrays up to 50 kilometers in diameter, but they have shrunk considerably to an average of about 1 kilometer"

I believe the impression that the sail provided sufficient thrust to cause appreciative acceleration comes from the very early texts where the sail size was approximately a factor of 100x the current sizes.

Even ye olde DropShips & JumpShips noted the jump sail had a hole for the stationkeeping drive to fire through and avoid falling into the star. The ancient 50km sails wouldn't generate enough thrust from light to lift a JumpShip against stellar gravity, either.

I suspect the impression comes from the name "solar sail." Real life solar sails and the hypothetical ones of the 1960s to 1980s generate thrust rather than photovoltaic power.

[Goose]

Yes, they do use thrust with the sail deployed. The sail is most often used at standard jump points, which are stationary with respect to the star and thus subject to gravity. To avoid falling (slowly) into the star, JumpShips use their stationkeeping engines, which necessarily fires through the dangling sail. (No, light pressure is not stronger than gravity at the jump points.)

OK: How does hanging out at a pirate point complacent this? Would you need more or less thrust?  O:-)

[worktroll]

General rule - more, much more.

Pirate points are a) much closer in system than regular points, so more solar pull, and b) also in proximity to other masses, which - being closer than the star - will exert their own pulls.

Short form, pirate points are probably more challenging for safe sail deployment.

[cray]

OK: How does hanging out at a pirate point complacent this? Would you need more or less thrust?  O:-)

That depends on the pirate point. If it's anywhere on the proximity limit like the standard jump points, then you fire up your stationkeeping engine like normal. If it's an L1 point, then you can go into a halo or Lissajous orbit around the point and not need your engine after the injection burn.

[The_Caveman]

OK: How does hanging out at a pirate point complacent this? Would you need more or less thrust?  O:-)

Pirate points are usually gravitationally balanced, at least to the degree that a KF bubble can form inside them. The point itself is in orbit, being created by the interaction of large bodies in the system.
My assumption of what goes on there is, the JumpShip arrives stationary relative to the target jump point (which is usually fixed to the star, so we can say the ship arrives stationary relative to the star), which in this case is a moving target. The JumpShip shows up in the pirate point's inertial reference frame and is therefore automatically in orbit of the star.
Unfortunately, pirate points aren't permanent fixtures because the gravitational forces are always changing, so you're going to need some stationkeeping thrust if you want to be there for more than a few hours/days. Otherwise you either wind up in a weird quasi-orbit like some Earth-crossing asteroids, or your orbit decays into the closest planet/moon.

General rule - more, much more.

Pirate points are a) much closer in system than regular points, so more solar pull, and b) also in proximity to other masses, which - being closer than the star - will exert their own pulls.

Not quite. The entire idea behind pirate points is they're areas where the various pulls cancel one another out. Over the short term, at least, you shouldn't need any thrust to remain on station. The need for thrust comes in when you're wanting to stay for longer periods and your orbit starts getting perturbed by n-body interactions within the system.

But because pirate points, being gravitational nexes (nexuses? nexi?), are going to attract all kinds of naturally occurring objects, you'll probably be burning a fair bit of fuel avoiding collisions with small trojan asteroids and the like.

[Goose]

 ??? I get how non-standard ProxiLimit points are just like the standard ProxiLimit ones, but I thought halo orbits where for the Legrange(s) 4 and 5, 'cause L1 was perfectly stable?

[The_Caveman]

??? I get how non-standard ProxiLimit points are just like the standard ProxiLimit ones, but I thought halo orbits where for the Legrange(s) 4 and 5, 'cause L1 was perfectly stable?

I believe L1 is only stable in a two-body system. Once you start adding the effect of other planets, moons, etc, it becomes unstable over the long term.

[cray]

My assumption of what goes on there is, the JumpShip arrives stationary relative to the target jump point (which is usually fixed to the star, so we can say the ship arrives stationary relative to the star), which in this case is a moving target. The JumpShip shows up in the pirate point's inertial reference frame and is therefore automatically in orbit of the star.

Exactly that.

Unfortunately, pirate points aren't permanent fixtures because the gravitational forces are always changing, so you're going to need some stationkeeping thrust if you want to be there for more than a few hours/days. Otherwise you either wind up in a weird quasi-orbit like some Earth-crossing asteroids, or your orbit decays into the closest planet/moon.

The L1 JUMP point is not quite at the same place as the L1 Lagrange point because the KF drive is blind to centripetal forces. Without centripetal effects, it would be further from the main body than the real L1 point and thus would fall into a highly elliptical orbit around the smaller body. Because the L1 points are not moving as fast** around the larger body as the smaller body, the resulting elliptical orbit would be retrograde around the smaller.

**They have the same radial velocity, but a lower translational velocity.

But because pirate points, being gravitational nexes (nexuses? nexi?), are going to attract all kinds of naturally occurring objects, you'll probably be burning a fair bit of fuel avoiding collisions with small trojan asteroids and the like.

The only viable Lagrange jump points are the L1 points - see p. 134 StratOps. They are not stable over periods of weeks to months, and thus will tend to shed anything not actively stationkeeping. The astronomical satellites at the Earth-sun L1 point need 30-100m/s per year, which is 0.1 to .33 fuel points.

[edit] I see you noted the instability while I was typing.

??? I get how non-standard ProxiLimit points are just like the standard ProxiLimit ones, but I thought halo orbits where for the Legrange(s) 4 and 5, 'cause L1 was perfectly stable?

L4 and L5 are not viable jump points. They are constructs of both centripetal force and gravity. Only L1s work.

[Goose]

I know only the L1 is jumpable (that's why I didn't mention Ls 2 and 3;) But I've only heard of halo orbits in association with Ls 4 & 5 …

So: Tell me about the need for a halo orbit at L1. :-\

[edit][reads second paragraph] [face palm]

Shouldn't we come up with a better name then "sort'a-near-de-L1?"[/edit]

[cray]

I know only the L1 is jumpable (that's why I didn't mention Ls 2 and 3;) But I've only heard of halo orbits in association with Ls 4 & 5 …

So: Tell me about the need for a halo orbit at L1. :-\

L4 and L5 don't NEED a halo orbit per se. The L1 point is another matter:
Explanation: https://en.wikipedia.org/wiki/Lagrangian_point#Stability
Example: https://en.wikipedia.org/wiki/Solar_and_Heliospheric_Observatory#Orbit

[Goose]

Welp: That's the page, other then the part where I remember the two types of L-points bass ackwards. [run away]