Surveying a system from a hex away.
- Thread starter RogerD
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Scope (video-enabled telescope) ought to do it, if you can get a long enough baseline (combine/compare multiple images from distant locations). An in-system jump would make this easy, otherwise, a long-enough normal-space transit would suffice given typical starship acceleration capability.
Better telescopes and a longer baseline (using a couple of 1-parsec jumps between observation points) could give even longer detection ranges.
BackworldTraveller
SOC-13
Taking a look at the exoplanets stuff available for the last 1/4 century, that's even possible at TL8!
AnotherDilbert
SOC-14 1K
Under the rules, by normal spacecraft sensors? No.
Sensors have defined max ranges, see B2 p140-141. A standard Scope would resolve a ship (Size=7) at S=4 and a gas giant (Size=14) at S=11.
The best you can do with Imperial tech is presumably EMS or Grav sensors that can detect a ship at S=7 and hence presumably a GG at S=14 (~40 AU [B1, p31]). If the GG is a proto-star and emits neutrinos a neutrino sensor would add a few range bands.
Note that you must use a passive sensor, as active sensors have a max range of S=7 (B2, p141).
Sensors have defined max ranges, see B2 p140-141. A standard Scope would resolve a ship (Size=7) at S=4 and a gas giant (Size=14) at S=11.
The best you can do with Imperial tech is presumably EMS or Grav sensors that can detect a ship at S=7 and hence presumably a GG at S=14 (~40 AU [B1, p31]). If the GG is a proto-star and emits neutrinos a neutrino sensor would add a few range bands.
Note that you must use a passive sensor, as active sensors have a max range of S=7 (B2, p141).
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mike wightman
SOC-14 10K
So technically sensors in T5 can not see (detect) stars...
I think this is probably something that needs fixing.
I think this is probably something that needs fixing.
AnotherDilbert
SOC-14 1K
It's not defined how they see stars, so there is no defined sensor task to detect. That does not necessarily mean they can't see them... There's a difference between "can see" and "precise targeting information produced quickly".
The sensor rules are written to detect spacecraft.
Along with a few other issues in T5...
RogerD
SOC-12
I guess given there are no rules, that just means if I want a rule, I simply have to make one up. Certainly I wouldn't expect a scan in the course of a space combat turn to show me all the planets in the system.
It's a little interesting as a thought exercise to try to apply these rules to planets and stars when exploring. I could imagine it being quite difficult to detect even a LGG at O=20, much less around a star a parsec away.
The essential elements (size, distance, skill, the sensor used and target characteristics) are there in the sensor rules, but I guess they'd have to be adapted somehow for this purpose or a new task would need to be defined for it.
Pulling from other sources doesn't help as much as I'd like - TNE talks about doing this scan (presence of a gas giant, not necessarily a count) with an 80% probability of success but doesn't give any task parameters. World Builder's handbook talks about spending 1 hour per detectable body to detect the contents of a system from inside the system, but says nothing about from outside the system. LBB2'77 p.35 talks about predicting presence of gas giants from a parsec away.
Maybe something like this?
To detect gas giants in system 1pc away (variable, a week)
Impossible (7D) ≤ Edu+Sensors+Astrogation+Mods (uncertain (1D))
Cooperative Sensors + Author
Mods:
+ Sensor TL
+ Sensor Mod
It's a little interesting as a thought exercise to try to apply these rules to planets and stars when exploring. I could imagine it being quite difficult to detect even a LGG at O=20, much less around a star a parsec away.
The essential elements (size, distance, skill, the sensor used and target characteristics) are there in the sensor rules, but I guess they'd have to be adapted somehow for this purpose or a new task would need to be defined for it.
Pulling from other sources doesn't help as much as I'd like - TNE talks about doing this scan (presence of a gas giant, not necessarily a count) with an 80% probability of success but doesn't give any task parameters. World Builder's handbook talks about spending 1 hour per detectable body to detect the contents of a system from inside the system, but says nothing about from outside the system. LBB2'77 p.35 talks about predicting presence of gas giants from a parsec away.
Maybe something like this?
To detect gas giants in system 1pc away (variable, a week)
Impossible (7D) ≤ Edu+Sensors+Astrogation+Mods (uncertain (1D))
Cooperative Sensors + Author
Mods:
+ Sensor TL
+ Sensor Mod
Spinward Flow
SOC-14 5K
Well ... ACTIVE sensor scans are going to be "right out" as they say.
At 1 parsec distant, you would be looking at a ~6.5 year round trip at light speed for any "ping" sent to a neighboring hex.
That means that your only options are PASSIVE sensors scans only.
I was going to point this out, but @BackworldTraveller got here ahead of me.
Using radial velocity astrometrics (looking for stellar "wobble") it's actually easier to find indications of massive planets around other stars than the alternative of a direct transit occultation event (which requires precise alignment and timing). Transit occulations of the parent star however make it a lot easier to gather all kinds of data and information related to details of an exoplanet (starting with spectroscopy, among other key data points).
mike wightman
SOC-14 10K
All you need is a James Webb equivalent and a bit of time:
www.nasa.gov
NASA’s Webb Space Telescope to Inspect Atmospheres of Gas Giant Exoplanets - NASA
In April 2018, NASA launched the Transiting Exoplanet Survey Satellite (TESS). Its main goal is to locate Earth-sized planets and larger “super-Earths”
www.nasa.gov
AnotherDilbert
SOC-14 1K
Quite, make something up.
I would say that is too easy?
7D averages 24.5 with low dispersion.
With just a TL-12 console and default sensor and no skill, that's about 50% chance?
With a TL-15 ship it's nearly automatic?
There should be a hefty negative DM for distance? If we can do it at 1 Pc, we can do it at 2 Pc, it's just more difficult or needs a more sensitive sensor.
Astrogation is mostly jump space navigation, with a minor in sensor reading. I would use Physics as a bonus skill. something like:
Edu + (Sensor or Astrogation) + Physics + Sensor range + Sensor Mod - N×distance + target size?
Or perhaps Sensor, Astrogation, or 2×Physics, with just Sensor and Astrogation substitutable with a console? Sorry, I just like the idea of this not being a standard shipboard task, but something for a University and a few undergrads.
Sensor range should be rewarded? I should be easier with a longer ranged = more sensitive sensor?
Target size should be involved, a star is easier to detect than a GG, that is easier than a planet?
RogerD
SOC-12
I deliberately didn't write that so that you can sub console for your skills (I like emphasizing characters over equipment), but I can see where the logic of T5 demands that. I was assuming 7+3+3 for average stats and skills. With that, I came up with typical values of 7+3+3+15=28 at TL 15 with no special sensor mod. That's 81% chance, which matches up with the TNE 80% accuracy idea. You do also have opportunity for spectacular results with this. Allowing console would up 7+3 to the TL, so at TL 15, that would be 15+3+15=33, or 98%, so yes, nearly automatic.
I'd certainly allow relevant knowledge skills, if present. Planetology or Physics could work for me, maybe other things not listed.
I like the idea of extending to other object types and ranges, but honestly a simple -1 for size to detect a planet vs. a gas giant is not that satisfying to me, and for stars, I would double their sizes (they are active sources). The relevant sizes are S=13 (Planet), S=14 (Gas Giant), S=15 (Star), S=16 (Giant Star).
I also like the idea of using the sensor range as a bonus - a deep space sensor should do better than a standard sensor. If you look at the max range table, it appears there is a per-sensor range value as well you could take into account. Something like:
Mods:
+Sensor range - 7 (Ex: +0 for standard range, +5 for deep space)
+Space range to detect ACS for the sensor type (Ex: +4 for Scope)
I feel like that then needs to be compensated with more dice or an overall mod which I was trying to avoid in the original formulation.
I looked at range as defined in T5. Max defined range is S=23 which is 1pc. Space ranges seem to be roughly doubling every range band, so you could do something like -1 per doubling after one parsec?
What do you think about the duration I proposed? (variable, a week)?
AnotherDilbert
SOC-14 1K
Quite, I would call that too easy, but it's your campaign. If it's 80% and not a life-or-death situation, I wouldn't bother rolling, just let it take a week.
Agreed, -1 per size smaller is too little. It would have to be tuned to the difficulty of the task? And, say, a blanket +5 to detect and pinpoint active stars?
Sounds reasonable. +5 is a huge mod, but so it should be.
Agreed, it has to be tuned.
I would say a little too easy, we don't want the players surveying systems 5-10 Pc away with standard shipboard sensors?
Radiation (sensor signals) attenuates by 1/r2, so a mod -d2 would be appropriate? Basically 1 Pc is OK, 2 Pc is difficult, but off-settable with a good sensor, but 3 Pc starts to get problematical?
Sounds reasonable. We need free space with no disturbances and a free field of view of the target system, but that should not be a problem with an M-drive.
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Enoki
SOC-14 1K
Wouldn't this ability be a necessity for ships that do surveying and scouting of new systems? After all, if they are going to jump into a system that hasn't been surveyed accurately for planets and planetary motion it'd be hard to jump to within 100 diameters of one to come out of jump, if that is how you interpret the jump rules...
mike wightman
SOC-14 10K
CT Alien Modules 1 and 4 had rules for detecting gas giants with a range of three parsecs/hexes:
AnotherDilbert
SOC-14 1K
You automatically exit jump at the 100D limit, so just aim for the star? I don't see the problem.
BackworldTraveller
SOC-13
Just how far will an average star have travelled in 3 and a bit years? Could you miss the 100d limit by just aiming at it?
mike wightman
SOC-14 10K
The relative velocity between stars is 10 to 20 km/s, so about 1,000,000-2,000,000km.
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Would something like this be "routine" "science equipment" on a starship? Obviously, today, they're a bit specialized.
Currently most extrasolar planets are detected using standard optical telescopes. They basically record, for lack of a better term, the "flicker" of the star. It's "dimming" behavior. But this will take months to years, as it's based on the orbit of the planet.
But in the end, the fastest way is simply to go there. Get a J1 ship with doubled up tankage so they can make it back, and jump. In 2 weeks you will know. In 4 weeks, if the ship stays, you'll probably have the orbits of all the major worlds of the system. I bet you can do a rough system survey with a computer driven scope along the ecliptic to find any planets on your side of the star quite quickly.
It's "safe" because of the 100D effect. You'll not collide with, well, anything. (Cue Douglas Adams and "space is big...")
AnotherDilbert
SOC-14 1K
10 km/s × 3600 s/h × 24 h/day × 365 day/year × 3 years ≈ 1 000 000 000 km.
The 100D limit is in the 100 000 000 km range.
Yes, you could miss the star, unless you compensate for relative motion. Luckily it's very easy to measure.
Take a picture with, say, an hour between; see how much the star have shifted. Closing speed is given by doppler-shift of the light. Distance is given by parallax shift.
AnotherDilbert
SOC-14 1K
Do ships need them for routine operation: No.
Do ships routinely measure things that far: Yes, that's what we are aiming for when we jump.
Presumably we are aiming for the star, with an offset calculated for the current position of the target planet given by the nav charts?
Agreed, but it might be nice to know that there is fuel to harvest there, incase we don't have fuel for both jumps and an extended survey period, hence looking for GGs.
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