Micro jumps?

[Blue Ghost]

Can someone tell me if rules exist for using the jump drive to travel interplanetary distances? I thought I read something somewhere over the decades, but it escapes me. I might be thinking of another system.

 

[whulorigan]

Can someone tell me if rules exist for using the jump drive to travel interplanetary distances? I thought I read something somewhere over the decades, but it escapes me. I might be thinking of another system.

It is called a "microjump" or "Jump-0", but for all practical purposes it is the same as initiating Jump-1. A Jump-1 will handle any distance of 1 parsec or less, and takes 1 week, 100-diameter limit to 100-diameter limit.

 

[Blue Ghost]

Many thanks.

 

[aramis]

It is called a "microjump" or "Jump-0", but for all practical purposes it is the same as initiating Jump-1. A Jump-1 will handle any distance of 1 parsec or less, and takes 1 week, 100-diameter limit to 100-diameter limit.

T5 actually changes this slightly.
Jump 1 isn't "directly" capable of microjumps. (not H1 of microhop, S1 of microskip). 0.9 is as low as it can go.

J1 is capable of a 1 Pc jump that intersects the shadow of a target closer than 1 Pc.

So you can microjump to Sedna, but not to a point midway between jupiter and saturn.

 

[Carlobrand]

T5 actually changes this slightly.
Jump 1 isn't "directly" capable of microjumps. (not H1 of microhop, S1 of microskip). 0.9 is as low as it can go.

J1 is capable of a 1 Pc jump that intersects the shadow of a target closer than 1 Pc.

So you can microjump to Sedna, but not to a point midway between jupiter and saturn.

Is there a consequence in that system for running into a shadow? Or do you just precipitate out normally?

 

[aramis]

Is there a consequence in that system for running into a shadow? Or do you just precipitate out normally?

No major consequences.

 

[Blue Ghost]

T5 actually changes this slightly.
Jump 1 isn't "directly" capable of microjumps. (not H1 of microhop, S1 of microskip). 0.9 is as low as it can go.

J1 is capable of a 1 Pc jump that intersects the shadow of a target closer than 1 Pc.

So you can microjump to Sedna, but not to a point midway between jupiter and saturn.

Did Marc Miller do a designer's notes write up as to why the change?

 

[aramis]

Did Marc Miller do a designer's notes write up as to why the change?

No, but Cryton and I did a bunch of math which resulted in him making the change on durations. Robject, Greg Lee, and DonM saw and commented, as well.

We were working on it because we saw the potential to radically change the nature of the setting.. and that argument (in the social sciences sense, not the angry discussion sense) resulted in requests from Marc to run scenarios. We didn't know we'd succeeded until we got our 5.09 PDFs.

 

[whartung]

So, just to clarify, whats to stop me being at earth, "aiming" for Jupiter, and doing a Jump-1 to who knows where, only to "accidentally" pop out because of the interdiction of Jupiter?

 

[Xerxeskingofking]

as it stands, nothing. you'd spend a week in jump and precipitate out at Jupiter's 100D limit.

 

[Sstefan]

That's how I read it as well. It generally gets you toward the last "large" planet in the system, but I seem to recall that there would be a way to "target" something smaller, like an Oort Cloud.

 

[mike wightman]

The Terrans used their jump drive for fast insystem travel for 12 years before attempting to reach across an intersteller distance - and even then they did it in stages (according to CT canon they built intermediate refueling stops to extend range, according to GT:ISW they used a brown dwarf discovered between Sol and Barnard's Star).

The first use of jump drive was entirely within the Solar System; it enabled fast expeditions to the outer worlds of the system and made possible several new colonies in the outer worlds. UNSCA did not realize that the drives had a great enough range to reach the stars. UNSCA licensed its jump drive to its national members. Expeditions were launched farther and farther, to Uranus, Neptune, Pluto, and the Oort Cloud...
The range of the jump-1 drives first developed by UNSCA was insufficient to reach the nearest star- Alpha Centauri. It took several years before a US Space Force team based on Luna tried a mission which, in several trips, established an intermediate stopover and refuelling point about one parsec out. For various scientific reasons, the mission was to Barnard's Star instead of Alpha Centauri.

 

[mike wightman]

The definitive MWM article from JTAS 24 had this to say:

Microjumps
Any jump of less than one parsec is considered to be a microjump. Sometimes, it can be advantageous to jump within a system rather than use maneuver drives. If normal acceleration and deceleration would take more than a week, a microjump is more efficient. At 1g, any distance greater than one billion kilometers would be more efficient using a microjump.
Microjumps can also confuse an observer or enemy. Because a ship's jump destination cannot be predicted, a microjump within a system still leaves an impression that the ship has left; a week later, it emerges from jump in the same system, to the observer's confusion.

 

[BlackBat242]

For informational purposes I repost mike wightman's quote, with the source included:

The first use of jump drive was entirely within the Solar System; it enabled fast expeditions to the outer worlds of the system and made possible several new colonies in the outer worlds. UNSCA did not realize that the drives had a great enough range to reach the stars. UNSCA licensed its jump drive to its national members. Expeditions were launched farther and farther, to Uranus, Neptune, Pluto, and the Oort Cloud...
The range of the jump-1 drives first developed by UNSCA was insufficient to reach the nearest star- Alpha Centauri. It took several years before a US Space Force team based on Luna tried a mission which, in several trips, established an intermediate stopover and refuelling point about one parsec out. For various scientific reasons, the mission was to Barnard's Star instead of Alpha Centauri.

 

[Ex_Pendable]

So, just to clarify, whats to stop me being at earth, "aiming" for Jupiter, and doing a Jump-1 to who knows where, only to "accidentally" pop out because of the interdiction of Jupiter?

You'd shave off at least 572,743,600 km from the trip, depending on how close you are.

 

[Blue Ghost]

For informational purposes I repost mike wightman's quote, with the source included:

That's where I read it.

But now that's going to change? That does seem a pretty radical departure.

I'll be honest here, the only reason I bring this up is because I thought of writing a "carrier" story with said carrier using microjumps to patrol a system's Oort cloud, and in general it strikes me that type-Ts would make copious use of microjumps to patrol gas giants for pirates and wayward vessels in distress.

None of my groups used much interplanetary travel, but it strikes me that other groups probably have and continue to do so.

 

[aramis]

So, just to clarify, whats to stop me being at earth, "aiming" for Jupiter, and doing a Jump-1 to who knows where, only to "accidentally" pop out because of the interdiction of Jupiter?

If you aim for jupiter and miss, you'll end up 1 Pc from where you started, unless something else is in the way and bigger than you. For a scout courier, that appears to be about 5% of the time, an oort cloud object. If you're at the right angle, it might be one of the other outer planets. Or the edge of the solar zone. If you hit nothing, you end up in deep space.

No matter where, you exit after 7±1 days.

 

[Lycanorukke]

None of my groups used much interplanetary travel, but it strikes me that other groups probably have and continue to do so.

With the changes to M-Drive in T5 (drop to 1% efficiency at 1000D), micro-jumps for the outer system planets start becoming the norm as opposed to a way to save travel time for slow ships.

In our solar system the 1000D solar limit is about Saturn's orbit. You want to visit Uranus, Neptune, Pluto you can either coast (but not too fast as you have to slow down when you get inside the targets 1000D limit) or micro-jump.

For K and M stars the limit would be even smaller, so micro-jumps would be even more common.

 

[Blue Ghost]

It's been a while since I've looked at T5, so I'll take your word for it. The old interplanetary rules did seem a bit much for the kind of game Traveller was supposed to be.

Are the new microjump rules a reflecting in the advancement of jump technology, or are they an actual rewrite of the old rules?

 

[kilemall]

With the changes to M-Drive in T5 (drop to 1% efficiency at 1000D), micro-jumps for the outer system planets start becoming the norm as opposed to a way to save travel time for slow ships.

In our solar system the 1000D solar limit is about Saturn's orbit. You want to visit Uranus, Neptune, Pluto you can either coast (but not too fast as you have to slow down when you get inside the targets 1000D limit) or micro-jump.

For K and M stars the limit would be even smaller, so micro-jumps would be even more common.

Exactly why I ditched any thought of 'modern' M-drive for MTU, as the Oort Cloud setting is just too miserable being tied to gravitics.