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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

#81

Post by dc443 »

dmurray wrote: post #52
elliekelly wrote: post #20

Earlier quoted context omitted.

Somewhat related I saw it’s going to take NASA’s new Perseverance rover about 7 months to get to Mars and it’s traveling at something like 25,000 MPH. Since NASA had to take the planetary orbits and launch timing, etc. into account I’m assuming that’s the fastest ideal velocity for the rover but not necessarily the fastest possible. So I guess my question is, given that Ceres is so much further away than Mars, what’s…

Faster is normally not all that important: it's much better to save fuel and send more stuff than to get there a few months earlier. Fuel costs vary roughly with delta-V, the total amount you have to accelerate or decelerate your spaceship. Because of the tyranny of the rocket equation, they aren't linearly proportionate to delta-V, but in general, if it takes more delta-V it's going to be harder and more expensive t…

Based on the linked (very cool) map, I don’t think what you say is accurate? A flyby of Ceres would be slightly harder than entering Mars orbit, and entering Ceres orbit would be harder than entering Neptune orbit.

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

#83

Post by 618033988749894 »

op03 wrote: post #8
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).

I had to stand around waiting for a bus in 0 F for a few years of my life. Did not detect any life around that bus stop.

That was one late bus.

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

#84

Post by ncmncm »

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…

Rocky planets are interesting only to extreme primitives. Once you leave the nest, Oort cloud objects are the most useful. That is where to look for visitors.

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

#85

Post by ojnabieoot »

baggy_trough wrote: post #11
api wrote: post #6

Earlier quoted context omitted.

The question is whether there is a source of energy for that subsurface ocean. If it's geologically dead the entire thing could be uniformly quite cold. Unlike some of the moons of Jupiter and Saturn it's not headed by gravitational tidal effects.

If that's the case why would it be an ocean at all, rather than a block of ice?

The article said it was a brine ocean, so salinity or some other solute - even at Earth gravity and air pressure, highly saline water can have a freezing point as low as -20C.

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

#86

Post by WhompingWindows »

toshk wrote: post #16
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).

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?

Our biochemistry is based on the most frequently occurring elements in the solar system. It's the most likely biochemistry to use carbon, silicates for instance are much less likely for a number of reasons.

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

#87

Post by ncmncm »

randomdude402 wrote: post #79
vmception wrote: post #76

Earlier quoted context omitted.

Upper atmosphere of Venus could be high value, if we just shift the states and view the surface as deep underwater and the clouds as land.

I thought the atmosphere was mostly carbon dioxide and sulfuric acid. What makes it potentially high value?

Earth-normal gravity, Earth-normal temperature, Earth-normal pressure, concentrated solar power, breathing air is buoyant, plastic and carbon fiber structural material--and breathing air and water--are convertable from atmosphere, cloud water is heavily enriched with deuterium. Way nicer than Mars.

You can operate an unshielded nuke plant tethered some distance below your balloon habitat, no worries about leaks.

We don't know whether humans can survive for long at Lunar or Martian gravity. Zero-G we know is a problem. So, Venus might be the only other notionally habitable planet.

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

#88

Post by ojnabieoot »

api wrote: post #6
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 question is whether there is a source of energy for that subsurface ocean. If it's geologically dead the entire thing could be uniformly quite cold. Unlike some of the moons of Jupiter and Saturn it's not headed by gravitational tidal effects.

The idea of multicellular life on Ceres is implausible for the reasons you mentioned, but there could be something like archaebacteria or other extremophiles with very slow metabolisms and which don't reproduce very often. As it's a brine ocean, the water could be chemically "hot" enough that a form of life is sustainable in a bio-geological cycle.

Here's an interesting article exploring the lowest possible temperature for life on earth (which is largely focused on vitrification blocking cellular metabolism but has both theoretical and empirical insights): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3686811/pdf/pon...

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

#89

Post by henearkr »

at_a_remove wrote: post #48
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?

Numerous other ideas exist for alien life, but most of them have their shortcomings. It all boils down to chemical reactions and physics. Imagine a universe of only helium. No valence electrons would be readily available, so chances are you are not going to see helium molecules. Lithium, sure, as a metal. Continue examining various smaller (and more plentiful elements). Fluorine? Well, only one slot available, so you…

You only considered chemistry-based life. Cannot hold it against you of course. But some hard SF writers like Baxter also imagined life based on electromagnetic interactions, nuclear reactions (life in the mantle of a neutron star), fluid vortices and turbulences (life in liquid or gaseous planets), etc. Basically he included a lot of substrates that could be used to implement complexity.

Also, a big drawback of searching only chemistry-based life is that it limits a lot the range of viable temperatures. Would be too slow and simplistic at low temperatures, and a complete uncontrollable chaos at high temperatures.

In particular, finding a brine on an ice dwarf like Ceres is not very exciting, as the temperature is too low, and no interesting chemistry can happen.

Whereas other substrates could be totally fine at different temperature ranges.

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

#90

Post by [deleted] »

at_a_remove wrote: post #48
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?

Numerous other ideas exist for alien life, but most of them have their shortcomings. It all boils down to chemical reactions and physics. Imagine a universe of only helium. No valence electrons would be readily available, so chances are you are not going to see helium molecules. Lithium, sure, as a metal. Continue examining various smaller (and more plentiful elements). Fluorine? Well, only one slot available, so you…

[deleted]
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