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Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

theguardian.com

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Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#181

Post by Symmetry »

9nGQluzmnq3M wrote: post #158
gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

> the water on the surface is 20% carbon by mass Sorry, can you explain what you mean by this? Are you using "water" figuratively for all liquid, as opposed to H2O?

We conventionally call the Earth's seas "water" despite the fact that they have a lot of dissolved CO2 and fish in them. Presumably Ceres's seas don't have anything like a fish but without microorganisms to scavenge they'll tend to have a lot of carbon containing compounds.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#182

Post by Sharlin »

lopmotr wrote: post #175
f_allwein wrote: post #151

Earlier quoted context omitted.

in case you’re wondering: That’s between -163,15 and -118,15 °C.

You really shouldn't put that 0.15 on the end. The numbers weren't that accurate to begin with so it gives the false impression that those digits mean something. I hope it doesn't feel like I'm picking on you but I can't help myself saying something because this is a pet peeve of mine. Rounding appropriately is taught in physics class at school but I think most people don't learn that or think it doesn't apply outsid…

Not sure why you were downvoted. The concept of significant digits is pretty important.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#183

Post by rbanffy »

imtringued wrote: post #168
simonh wrote: post #167

Earlier quoted context omitted.

True, but in orbit refuelling means 3 or 4 additional refuelling launches, so now your cost per kg is back up to a few thousand $ per kg again. Still cheap for Ceres though.

Yeah, orbital refueling doesn't change the rocket equation unless you can manufacture fuel in space. The only benefit is that you don't need a bigger rocket.

We'll eventually get to the point where Starship-like rockets only ferry people, cargo, and, maybe, propellant to LEO for transfer to spaceships that don't need to go deep into any gravity well. These ships will then take you to orbit around your destination so you can board another shuttle to the surface.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#185

Post by dragonwriter »

progval wrote: post #166
bjo590 wrote: post #46

Earlier quoted context omitted.

No, it doesn't create a plot loop. The book explains that all of the H2O on Ceres was used to apply spin to Ceres to create artificial gravity. This is a symbol of Inner Planet's dominance over the Beleter's, because a _real_ Belter would never trade precious water for artificial gravity. This is mentioned fairly subtly in the first book, and is easy to miss while taking in the rest of the world. In addition the spin…

> For scientific context to my statement H2O can be turned into really good propellant Note that in The Expanse universe, water isn't usually used as propellant, but simply as reaction mass. All we know about the actual propellant is that it's used in fusion reactors and is surprisingly efficient.

> All we know about the actual propellant is that it's used in fusion reactors and is surprisingly efficient.

Since we're being specific with terminology, if it's used in a fusion reactor, it's not a propellant, since propellant is a combination of chemical fuel and oxidizer.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#186

Post by Symmetry »

PaulHoule wrote: post #65
toshk wrote: post #16

Earlier quoted context omitted.

I always wondered why we are overly focused on the conditions that created life on earth. Arguably it makes sense to see similar conditions lead to life. But do we really know enough to assume that's only way?

If your definition of habitable is "has liquid water" probably most of the habitable places in the universe are like Ceres, the moons of Saturn, even deep inside Pluto. Between the effects of pressure, geothermal energy, and gravitational tides you find liquid water in those places more than the inner solar system where water gets evaporated and blown away. (The trouble is that those places don't have sunlight and pr…

My pet theory is that life is pretty common in the universe, it happened on Earth almost as soon as the oceans formed. But photosynthesis, mitochondria, and multi-celularity each took a lot longer and probably represent the biggest barriers to intelligent life.

Plus, as you say, most liquid water is in the deep dark under ice sheets far from the nearest star which makes photosynthesis difficult.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#187

Post by Symmetry »

smithza wrote: post #13
gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

What of the lack of atmosphere and lack of active mantle/core? Solar energy has little chance of staying within the system.

The potential lack of vulcanic and geological activity now is a big problem. For the first 700 millions years life on Earth depended on chemosynthesis and that's where the energy for that comes from. Presumably there could have been more active geology far in the past, though, possibly implying life that died out.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#188

Post by rbanffy »

clarkmoody wrote: post #109
loosetypes wrote: post #91

Earlier quoted context omitted.

Would evolutionary timelines or cycles be slower in an overall colder planet? (Thinking of those interactive diagrams for temperature on the kinetic energy of molecules zooming around in closed space)

Did you ever read Dragon's Egg ? It's a speculative hard sci-fi that posits ultra-fast evolution for life on the surface crust of a neutron star !

It's an interesting idea, but I find characters developed on the surface of a neutron star will end up being implausibly flat, lacking any depth.

(badum tish)

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#189

Post by Symmetry »

shakna wrote: post #12
nerfhammer wrote: post #5

man, so many planets have subsurface oceans, there must be a lot of species of eyeless space whales across the universe

Earth might have a subsurface ocean as well [1], though I haven't found any follow up since 2014 on that one. [1] http://dx.doi.org/10.1126/science.1253358

That sounds like water in hydrated minerals rather than liquid water? In terms of settling inner solar system asteroids where the sun bakes everything you're looking for material with as much easily extractable water as concrete to make a comfortable home.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#190

Post by thefounder »

gaukes wrote: post #2

Ceres is one of the more interesting candidates for life in our solar system. Ceres is in the habitable zone for our solar system (although just barely), it's surface temperature is -30 F (eq. to winter in Greenland), and it's detected that the water on the surface is 20% carbon by mass (though that can mean a lot of things).

Source?
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