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[Maximum Spin]

"We didn't find any signs of extraterrestrial civilisations, and that was boring, so we made some."

[feelotraveller]

Protagoras's last stand.

[MrRoboto75]

look on the bright side, even if humans make earth a venusian greenhouse hellhole, life uh finds a way

[Telgin]

I guess we'll learn something from the science even if it turns out to not be alien life, such as new abiotic sources of phosphine, but I'll be very surprised if we ever find life on Venus.  It's not impossible, but its biochemistry would have to be very different from ours.

Still, gives us a reason to try to build more probes to study Venus, which is cool.

[Starver]

The discovery 'pinpoints' the concentrations to the 50-60km altitudes in the cloud layer. Which gives pressures from a tad over 1 times Earth sea-level up to not quite airline cruising altitude, and rough temperatures of 75°C reducing to -15°C. With representative Earth life found across both ranges.

There's the H₂SO₄ clouds, of course (not that we don't have extremophiles with this 'superpower', often in conjunction with heat) and that only gives justification for existing life perhaps adapting into existence in this band of atmosphere[1], given time, and flash-adaptation of wandering spore-life or home-grown abiogenisis in this very situ takes a lot more explaining, and seems to not have the "tidal pools, many little experimental test-tubes and crucibles" element that is a heavy theory in our own origins.

So I'd suggest (with no hands-on knowledge) that maybe pre-overheated Venus did much the same as us, and gradually it lost all but its simple cellular life able to drift on the high winds, with a carefully trimmed(/selected-for) microbuoyancy to keep drifting in layers that could perhaps provids a sulphur-biased biochemical energy pathway, with or without a photosynthetic element to it..? And it'd be a long-shot (or indeed a long time) before multicellular gasbags (or 'colony gasbags' reminiscent of a portuguese man-o-war?) appeared as a dominant lifeform.

Unless I'm being too conservative, especially as I don't know how long this life may have been floating around the venusian atmosphere, we don't entirely understand our own extreme-ancestry, and anything that took to being a microspore specialising in atmospheric floating may be much less prone to leaving fossils than those that more habitually became stromatolites (if they weren't the same thing, just in different modes of life).


[1] Though this could as easily be the inhospitabls 'graveyard' zone for life that exists elsewhere and 'spills its phosphine guts', or whatever decays to phosphene, into this layer once it leaves its much happier home layer...

[Starver]

Just an idle thought:
Phosphine: ~1.379 g/l (STP)
CO₂: 1.977 kg/m3 (gas at 1 atm and 0 °C)
...i.e. roughly 70% density in likish-for-likish conditions (c.f. Earth-atmosphere 1.29g/l, a reputedly viable 'lift gas' in future upper-atmosphere manned exploration of Venus), give or take the slightly different conditions of those measures, plus the wider range of conditions according to altitude that are relevent to the second rock from the Sun.

Apart from brownian/tubulent diffusion, it suggests a possible source below. Rising but simultaneously degrading or reacting with the sulphides/etc, to be most obvious during its rise, as it concentrates and before it dissipates again, perhaps itself evidence of a precursor phosphor compound elsewhere.

Or it suggests use as a lift-gas is possible (not found out much about the prevalence of other phosphor resources, yet, but you'd think it would have to be a common precursor to make phosphine a useful product just for density reasons - or at least the best handleable compared to pure hydrogen or oxygenated crackings-and-distillations), and these are escaped whiffs from injury or worse.

Or both. Imagine venereal (wo)men-o-war floating down at maybe 20-40km, dangling 'dredging' or 'trawling' tentacles into the further depths, perhaps even to the surface rocks (pulled up to avoid active vulcanism, or a small loss if the tips get singed), extracting phosphates and other useful substances, drawing them up into their more habitable layers of atmosphere to react (and/or photosynthesise, in a local manner, depending on how much cloud there is above[1]), in their own personal version of life.


I've yet to see what the phosphine normally degrades to (under the appropriate influence of sun'n'sulphates), and what signatures that might give that are detectable. If it's an ecosystem, I'd expect an 'unnatural' pipeline of further feeding frenzy to live upon the phosphine (living upon the wastes of other organisms), which might he easied to detect if these things happen in/emerge into the clearer air above the haze more than the phosphine-exhalers/farters/leakers below, whatever any of them are. Especially if it forms an active phosphor-cycle, which is almost expected if it is at all an important element in life (in whatever form), including geology and the local equivalent to hydrology.


[1] The sulphuric haze goes up to ~50km, also obscuring our view of what happens below this discovery, unless it ended up caught on a Venera lander/crasher camera, etc. Which we can probably presume it didn't.

[LordBaal]

https://phys.org/news/2020-10-spacecraft-titan-years-fusion.amp

Wow... those guys are stating a trip to Saturn in 2 years and a half, is not clear to me if is the round trip with no stops and two years or two and a half for a one way trip.

If is two and a half years to saturn it means like 50 days to Mars if my memory of planetary distance is not that rusty.

That is fucking fast.

[Madman198237]

https://phys.org/news/2020-10-spacecraft-titan-years-fusion.amp

Oh wow, somebody suggesting a means by which we could turn the theoretical efficiency and power output of a fusion reactor into thrust, how original.

It'd be more helpful if they stopped daydreaming about how cool it would be and actually started working on a fission-powered rocket which could actually be built and tested and employed and made ready for the replacement of its power source with fusion, instead of waiting for someone to come hand them a fusion reactor to fill in the big black box that is the power source for their design.

[RedKing]

OSIRIS-REx had a successful touch and go on asteroid Bennu!

They'll know some time tomorrow if they got a large enough sample or if they need to make a second landing.



Also, SpaceX did its first static fire of the triple-Raptor engine config for Starship.

[bloop_bleep]

It'd be more helpful if they stopped daydreaming about how cool it would be and actually started working on a fission-powered rocket which could actually be built and tested and employed and made ready for the replacement of its power source with fusion, instead of waiting for someone to come hand them a fusion reactor to fill in the big black box that is the power source for their design.

Well, they tried to do that already, with Orion, which was scrapped after a nuclear treaty, something about deploying multiple nuclear bombs throughout a whole vertical column of the atmosphere being undesirable or something. Besides I'm not sure that a nuclear fusion reactor is similar enough to a fission reactor in terms of weight, power output, power characteristics, fuel usage, required operating conditions, etc. that you can just make a fission reactor engine and then swap out a fusion reactor with some minimal adjustments and have the thing work.

[Eric Blank]

You could make a modular design, such as a craft which can be split up (sections effectively undocked), and then dock a new reactor (or whatever) section in the middle of the stack. Similar to the way the ISS modules needed to be connected (although I assume they're not truly modular in that they can be sealed off and disconnected, maybe at all), but just make one long stack with engines at the back.

It would be a totally novel design and probably need tons of new engineering, but once such modular construction is available, you could replace compatible components in orbit without having to scrap an older craft and launch a totally new one. Such as replacing an old defunct power plant, engine, or crew/work compartments with the latest model.

[wierd]

If you put enough fuel on board, and put a big enough power plant to use BOTH a magnetic ramscoop, AND a multiport ion thruster on a vehicle, you could then cruise through deep space while refueling the ion thruster in flight. (Ion thruster variant of the RAIR)

(The fission powerplant powers the magnetic ramscoop, which scoops up already ionized particles, and funnels them into the ion thruster's intake.  The ions are then accelerated in the ion engine, and shot out the back, conferring specific impulse to the vehicle. Like a RAIR, heavy radioactive nuclei from the fission reactor, aka, its waste, can be vented through the ion thruster, and ejected from the vehicle as well, but this would probably make space hippies angry.)

[Eric Blank]

How much waste product would that actually produce, though? Surely not a significant enough amount to cause problems?

[wierd]

Depends on a number of scenarios...

1) One-off vehicle going to a distant star-- eg, a robot probe mission. 

Long term effects: Basically nonexistent.

2) A larger vehicle carrying humans, going to a distant star.  The reactor needs to be much bigger, and thus needs to have more fuel rods installed-- The need for constant power to keep the crew from freezing to death, etc-- means that maintenance windows to refuel the reactor and dispose of waste will be spread apart by long periods of time, and that means larger quantities of waste needing to be eliminated in sudden large quantities after refueling the reactor.  This could result in large clouds of radioactive products after vaporizing the waste to send it through the ion engine.

Long term effects:  unknown. Potentially large clouds of radioactive gasses would dot the vehicle's path.

3) Somehow long-haul interstellar travel (or worse, intrastellar travel inside the solar system) becomes very very popular, and this kind of engine is preferred when transporting humans around. Has the problem of scenario 2, but now has those clouds of debris piling up in frequently traversed parts of the solar system. or frequently traversed parts of the interstellar medium.  Risks to later generations of vehicle would compound as these clouds of particle gasses start increasing in frequency and density.

Long term effects:  Potentially troubling.


Really, you would only want to use this kind of engine for interstellar voyages.  Inside a star system, you could just wave a big mylar sheet at the solar wind, and get almost as much specific impulse for basically free-- at least when traveling outward.  (which could be redirected inward with gravity slingshot maneuvers, using small amounts of conventional fuel to do the orbit burns)


Want to send a probe to that probably scorched rock orbiting Proxima Centauri?  Sure-- use the fission powered NAIR/ION hybrid.  The solar wind particles of Proxima would slow the vehicle down (because the ramscoop would start getting pelted with solar wind particles, the combined impulse of which would be greater than its thrust-- and the ramscoop as a very large area) as it approached, so you get free braking.

Want to send humans? As long as you dont send humans all that often, you could probably get away with the scaled up version--- but if you suddenly are sending ships all the damn time, you should use a fusion rocket instead.

[Starver]

If you end up (knowingly or otherwise) visiting an inhabitted exoplanet, be aware that your vehicle may not be strictly allowed, or at all welcome, by the local ordinances upon your arrival...