Planetary Masking

[Longboat]

I was looking at the Traveller Map, and on the world detail, I noticed a time mention for "time to jump point".

Is that something new in MGT that considers jump masking by the system's star or other close large worlds (as when the main world is a satellite of a gas giant)?

 

[GabrielGABFonseca]

I was looking at the Traveller Map, and on the world detail, I noticed a time mention for "time to jump point".

Is that something new in MGT that considers jump masking by the system's star or other close large worlds (as when the main world is a satellite of a gas giant)?

What you are seeing is a feature of Traveller Worlds, not Traveller Map. Traveller Map links to Traveller Worlds, but Traveller Worlds is a separate website maintained by separated people.

Traveller Map hosts the Traveller 5 Second Survey, the official dataset from which Traveller products are made, but Traveller Worlds takes that data and uses pseudorandom procedural generation to create a star system from that official data using the Traveller 5 system/planet creation rules, plus a few extra things from other editions, and thus its outputs are not canon (case-in-point; look at the Terra system or Regina system).

The "Time to Jump Point" entry in Traveller Worlds simply automates the calculations of how long it would take a ship to go from the planet's surface to the edge of all relevant 100D limits. It has nothing to do with anything introduced by Mongoose Traveller, it's the same 100D limit as always.

 

[Longboat]

The "Time to Jump Point" entry in Traveller Worlds simply automates the calculations of how long it would take a ship to go from the planet's surface to the edge of all relevant 100D limits. It has nothing to do with anything introduced by Mongoose Traveller, it's the same 100D limit as always.

I got you. I guess there is just no way to figure in jump masking, especially by the system's star, without knowing the diameter of the star and the distance the world is from the star (and similar figures for satellites as main worlds).

It takes elbow grease and work to figure that out.

I've wondered how to easily bring jump masking to the game--something that is always ignored--in a simple way for a long time, and it eludes me.

 

[MasterGwydion]

I got you. I guess there is just no way to figure in jump masking, especially by the system's star, without knowing the diameter of the star and the distance the world is from the star (and similar figures for satellites as main worlds).

It takes elbow grease and work to figure that out.

I've wondered how to easily bring jump masking to the game--something that is always ignored--in a simple way for a long time, and it eludes me.

Jump Masking is basically Referee fiat. There is no real way to determine it scientifically within the information provided by Traveller. Space in Traveller is 2D, not 3D for one, and motion of planetary systems is sufficiently complex the 99% of Referees wouldn't even want to try it.

I actually do not use jump masking in My games.

Edit - I do use jump masking when the planet you are heading for is within the 100D of a star or a gas giant moon is within the 100D limit of the gas giant.

 

[Bense]

I've wondered how to easily bring jump masking to the game--something that is always ignored--in a simple way for a long time, and it eludes me.

World Builder's Handbook, if you want to build the system. Referee's fiat if you just want to keep your players in space longer.

 

[hopsnbaer]

Gurps had a simple way to figure it out. I thought it was in the Far Trader book, but i may be incorrect. It was similar to roll 2d6 for each system. If you roll a 9 or higher on both rolls the jump is normal. If either roll is below 9 add about 30 or 40 hours to the travel time in system due to Jump masking.

 

[Bense]

Gurps had a simple way to figure it out. I thought it was in the Far Trader book, but i may be incorrect. It was similar to roll 2d6 for each system. If you roll a 9 or higher on both rolls the jump is normal. If either roll is below 9 add about 30 or 40 hours to the travel time in system due to Jump masking.

The simplest rule is in the GURPS Traveller corebook too: "Roll 8 or less on 3d for both origin and destination; success means that the jump point is unmasked. Masked jumps add about two days (44 hours) to normal travel time."
This rule would mean that most of the time the jump point is masked (being only unmasked about 5% of the time).

In Far Trader there's a table that takes the star spectral types into account. The "8 or less" roll is for "Unknown" spectral types if the GM doesn't want to mess with the table. For smaller stars the jump points are always masked.

 

[CordwainerFish]

IMTU it's mass, not diameter. Diameter doesn't work and play well with the principle of locality, and I know how to use a slipstick.

 

[hopsnbaer]

The simplest rule is in the GURPS Traveller corebook too: "Roll 8 or less on 3d for both origin and destination; success means that the jump point is unmasked. Masked jumps add about two days (44 hours) to normal travel time."
This rule would mean that most of the time the jump point is masked (being only unmasked about 5% of the time).

In Far Trader there's a table that takes the star spectral types into account. The "8 or less" roll is for "Unknown" spectral types if the GM doesn't want to mess with the table. For smaller stars the jump points are always masked.

I knew I was close.

 

[Longboat]

This rule would mean that most of the time the jump point is masked (being only unmasked about 5% of the time).

In Far Trader there's a table that takes the star spectral types into account. The "8 or less" roll is for "Unknown" spectral types if the GM doesn't want to mess with the table. For smaller stars the jump points are always masked.

That's pretty cool. And the 5% unmasked makes sense as the main world is usually in the habitable zone close to the star.

 

[Condottiere]

Diameter stands in for actual gravitational force.

I'm sure black holes are somewhat disproportional, to their presumed diameter.

 

[Bense]

That's pretty cool. And the 5% unmasked makes sense as the main world is usually in the habitable zone close to the star.

That the mainworld is probably in the habitable zone does seem to be one of the assumptions of the system in Far Trader.

 

[MasterGwydion]

That the mainworld is probably in the habitable zone does seem to be one of the assumptions of the system in Far Trader.

Do not forget that some stars have habitable zones inside the 100D limit.

 

[Bense]

Do not forget that some stars have habitable zones inside the 100D limit.

Yes, the table in Far Trader shows that a jump is always masked for G5 or cooler stars. And for any planets orbiting O-B stars it's never masked, because the habitable zone for those stars is well outside their 100D limit.

 

[Longboat]

Do not forget that some stars have habitable zones inside the 100D limit.

I've noticed, using CT materials, that most of the main worlds in the habitable zone, are within the 100D limit, thus they are jump masked.

 

[MasterGwydion]

Earth is Jump Masked.

Diameter of the Sun is roughly 140 million kilometers. 100D = 14 billion kilometers.
Diameter of Earth's orbit is roughly 940 million kilometers. Plus Earth's diameter and 100D limit... Earth's 100D limit is roughly 942 million kilometers.
Giving you a difference of roughly 12.5 billion kilometers.

Did I screw My math up? That doesn't seem right... ???

 

[Terry Mixon]

Earth is Jump Masked.

Diameter of the Sun is roughly 140 million kilometers. 100D = 14 billion kilometers.
Diameter of Earth's orbit is roughly 940 million kilometers. Plus Earth's diameter and 100D limit... Earth's 100D limit is roughly 942 million kilometers.
Giving you a difference of roughly 12.5 billion kilometers.

Did I screw My math up? That doesn't seem right... ???

The Earth orbits at 150,000,000 km. That puts it 10,000,000 km outside the sun’s 100 diameter limit.

 

[ottarrus]

I was looking at the Traveller Map, and on the world detail, I noticed a time mention for "time to jump point".

Is that something new in MGT that considers jump masking by the system's star or other close large worlds (as when the main world is a satellite of a gas giant)?

Jumping into a system causes a burst of neutrinos around the emergence zone. I suppose it might be possible to plot a course to emerge on the other side of the sun, but that is at the price of an extended transit time to the mainworld.
Merchants wouldn't countenance the waste of fuel and time, both of which cost money, and most systems would consider anyone doing so without an IISS transponder criminal and/or hostile.

 

[Limpin Legin]

Earth is Jump Masked.

Diameter of the Sun is roughly 140 million kilometers. 100D = 14 billion kilometers.
Diameter of Earth's orbit is roughly 940 million kilometers. Plus Earth's diameter and 100D limit... Earth's 100D limit is roughly 942 million kilometers.
Giving you a difference of roughly 12.5 billion kilometers.

Did I screw My math up? That doesn't seem right... ???

Sun's Diameter* = 1.39 million km
Sun's 100D = 139 million km
Distance of Sun to Earth* = 150 million km
ie, as @Terry Mixon says, Earth is outside Suns 100D limit by 11 million km
Earth's Diameter* = 6,371 km = 0.006371 million km
Earth's 100D = 0.637100 million km.
* Source: NASA

 

[Condottiere]

For busy routes, spacecraft terminals would be placed in likely, if distant, exit and entrance points.