Atmosphere codes E and F
- Thread starter 77topaz
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Am I correct in understanding that atmosphere codes E and F have basically swapped meanings in Traveller 5 vs. every other edition of Traveller?That is, a world that would be atmosphere E in another edition would be atmosphere F in Traveller 5, and vice versa?
They have been swapped in both T5 and MgT from all previous editions.
Older Editions:
E = Ellipsoidal
F = Thin, Low
T5 & MgT:
E = Thin, Low
F = Unusual *
* - Which probably includes, but is not limited to, Ellipsoidal
Yes. And it appears that the T5SS data on TravellerMap may have overlooked the change as well. I believe Easter in the Solomani Rim is still classified as atmosphere type "E" [= Thin, Low] , and the whole reason for the name of the world is due to its egg-shape (which would now make it type "F" [= Unusual]).
Probably all of the T5SS data should be double-checked as well to make sure that the atmosphere code lines up with the previous data on affected worlds (unless there is a deliberate canon-change, of course).
Ellipsoidal can't happen for more than a few thousand years...
Anything small enough to not self-round is too small to hold a noticeable atmosphere.
Anything big enough to hold a significant atmosphere self-rounds by gravity, and further, is usually big enough for the atmosphere to be conformal... note that earth is off from true sphere by up to about 27 km, but the atmosphere isn't significantly thinner at the flattened poles... nor significantly thicker at the equator. (In fact, at the equator, the hadley cells REDUCE local air density slightly...)
What is the difference between E (thin, low) and codes 2-5?
Or D (dense, high) and codes 8-9?
Or D (dense, high) and codes 8-9?
E (Thin, Low) means the planet surface is either in vacuum or near-vacuum, but enough atmosphere accumulates in very low valleys or crevasses to be breathable.
D (dense, high) means that at the surface the atmosphere is too dense to be breathable, but on high mountains or plateaus it thins out enough to be breathable.
How do these manifest? What are the different pressures between too little/just right/too much?
How much elevation change is necessary? How much gravity? I assume that the higher pressures at lower altitude are there because of the "weight" of the upper atmosphere compressing the lower atmosphere?
How low must a valley be, how high the canyon walls to contain the atmosphere? Does the atmosphere thin out at the ends of the canyon?
Essentially, think about Canyon and Plateau in Niven's Known Space...
Canyon
Gs=0.45
Ps ≤0.25 Bar
P canyon bottom >0.25 Bar - at depths exceeding MSL–4km... so a 1 cm gains about G* average density x average height * local gravity. Works out to about 1.2 bar at the deepest point of the canyons caused by the Treatymaker.
(air at STP = 1.3 kg/m^3.... 1 km x 1cm^2 = 6km *1000*0.01=60 cubic meters per cm^2 between median canyon depth and the surface if Ps=0.1.... )
An then there's Plateau - Surface pressure is about 3 bar and 20% O2... which makes the surface toxic levels of O2. (600 mBar of O2 is mildly toxic...) That there are other taints... CO, CO2, both at PP > 100 mBar - rather toxic, actually, plus settled out NO2...
(I'm looking in the Ringworld RPG for numbers... and having to fudge and work from memories of the novels, as well.)
Both appear to be the prototype writeups for these situations.
I remember Louis Wu and Speaker-to-Animals dicussing it but it wasn't anything they both couldn't handle, i.e. no respirator/oxy bottle/filter mask needed.
Other volumes note that the surface isn't livable pressure. You can function in 0.2 Atm for a few hours... if it's at least 0.05 bar PPO2, you can stay alive and dizzy... but you'll die if you try to live there unaided.
Hell, the shuttle EVAs are in 0.2 Bar... PPO2 0.19 Bar as well... (the remainder is their exhaled CO2...).
Supplemental O2 for ground dwellers is recommended at about 9 psi (12K ft MSL), and essential for significant function at about 7 PSI (about 0.47 bar, 0.1 bar PPO2). High altitude adapted folk can function in about 1/2 the PPO2...
People function in 6 PSI with supplemental O2 on an annual basis - climbing Everest or K2, they hit 0.32 Bar, and PPO2 0.07 bar... But only the sherpas and some south americans can do so for more than a few hours without supplemental O2...
Yes, in the novels the air is breathable high in the plateau or deep in the canyon. Why did people settle there?
Described in the books also was there were original unmanned survey probes. They happened to land in these marginal locations, collected data and signaled back. The generational ships went out and then some time later, oops, we can't go back...
Described in the books also was there were original unmanned survey probes. They happened to land in these marginal locations, collected data and signaled back. The generational ships went out and then some time later, oops, we can't go back...
I thought it was 'Mt. Lookit That !' that had a narrow area of breathable air. The Ring World had people living at surface level and breathing fine. Thats the books I was refering to.
RingWorld doesn't describe the originals well; other books in the Known Space series (including the Man-Kzin Wars) do.
