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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

#241

Post by holycrapwhodat »

irrational wrote: post #239
Afton wrote: post #236

Earlier quoted context omitted.

what an odd hill to die on...

Probably depends on your age. Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included? Or did you grow up afterwards and learn from elementary school that Pluto is not a planet so people who still insist that Pluto is a planet seem anachronistic? It would be like Hydrogen being removed from the periodic table an…

> Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included?

Yup, grew up with all of those things.

And when they discovered more Plutoids - some even bigger than Pluto - when I was in high school, I loved watching science change as more information came in. Because that's what science does.

I love that we now have better definitions to more accurately describe bodies orbiting a star, and Pluto is definitely not a planet the same way the 8 planets are.

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

#242

Post by linuxftw »

saalweachter wrote: post #226
shadowprofile77 wrote: post #218

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

I suppose the question is whether "dwarf" is a modifier to "planet" or whether "dwarf planet" is a compound word that cannot be split without losing meaning. I would lean toward the former -- if there was not room in the headline for "Dwarf planet Ceres", referring to it as "Planet Ceres" still adds information and clarifies helpfully. "Ceres" may not be familiar enough to most readers for them to instantly think, "O…

Indeed, 'a dwarf something' is 'a something,' such as a 'dwarf star' or a 'dwarf tree.'

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

#243

Post by int_19h »

throwaway2048 wrote: post #74
at_a_remove wrote: post #48

Earlier quoted context omitted.

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…

Another problem with silicon is that its basic oxide (Silicon Dioxide) is a solid that is non-reactive with virtually everything. If you assume water based life, there is almost certainly going to be oxides involved, such as how CO2 is involved with earth life. And I think water based life chemistry is an extremely good bet, because alternative liquids based off of light, common elements are either only liquid at ver…

> common elements are either only liquid at very low temps, (ammonia, methane)

But they are very low temps on our scale, which is centered around water.. There are many places, even in our own solar system, where these are liquid all the time, and water is solid all the time.

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

#244

Post by rbanffy »

valuearb wrote: post #237
UnFleshedOne wrote: post #234

Earlier quoted context omitted.

You could probably aerobrake to get into orbit instead. But eventually it might make sense to build ships that are never supposed to touch atmospheres, or only upper layers. Some design constraints can be relaxed then.

There definitely is a place for Aldrin Cyclers, not soon, but eventually. It’s not to save on fuel, but to provide safer and healthier accommodations for the trip. How it will likely work is passengers will take a Starship to orbit. It will be refueled in LEO, then accelerate to Mars injection velocity to match orbit with a passing Cycler. It will dock with the Cycler, passengers will switch to the Cycler for the dur…

In the end you save a lot on fuel - you don't need to bring along shielding, life support equipment for the duration of the trip (only expendables and replacement parts).

The trajectory adjustments may be small enough that Hall thrusters, or even just reorienting solar panels or inactive radiators get enough light pressure to make it work. If we are OK with spending a little more propellant, the cycler can be put on a shorter quasi-cyclic orbit that requires course corrections on every pass (IIRC, the shortest trajectory Aldrin considered in his paper would enter Earth's atmosphere, or crust, I don't remember). The cycler maintenance cycles also don't need to coincide with in-transit crews and, in some passes, crews can bring more cargo (or the cycler can dock with autonomous cargo freighters).

If the cycler is large enough, it may have its own food production, so you don't need to carry that too, but then we can also imagine it as a full habitat that's permanently populated and passes by Earth and Mars every now and then and also plants us firmly into science fiction territory. IIRC, the shortest real cyclic path also takes a trip to the Asteroid belt before passing Mars on its way back to Earth. That, I imagine, would be a popular destination for future space colonists looking for resources in the belt to supply passing cyclers.

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

#245

Post by throwaway2048 »

int_19h wrote: post #243
throwaway2048 wrote: post #74

Earlier quoted context omitted.

Another problem with silicon is that its basic oxide (Silicon Dioxide) is a solid that is non-reactive with virtually everything. If you assume water based life, there is almost certainly going to be oxides involved, such as how CO2 is involved with earth life. And I think water based life chemistry is an extremely good bet, because alternative liquids based off of light, common elements are either only liquid at ver…

> common elements are either only liquid at very low temps, (ammonia, methane) But they are very low temps on our scale, which is centered around water.. There are many places, even in our own solar system, where these are liquid all the time, and water is solid all the time.

Sure but the problem is that chemical reactions are MUCH slower at such low temps, perhaps much too slow for life to exist.

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

#246

Post by rbanffy »

UnFleshedOne wrote: post #234
valuearb wrote: post #219

Earlier quoted context omitted.

That would be massively inefficient for travel to Mars, because you can Aerobrake to land and make fuel on Mars for your return.

You could probably aerobrake to get into orbit instead. But eventually it might make sense to build ships that are never supposed to touch atmospheres, or only upper layers. Some design constraints can be relaxed then.

The most efficient propulsion methods are not suitable for atmospheric flight or landing because of their low thrust, but are excellent for long-duration interplanetary flight where you can "burn" for hours, or days, to change between parking and transfer orbits.

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

#247

Post by syshum »

Afton wrote: post #236
syshum wrote: post #229

Earlier quoted context omitted.

>>If even the much larger Pluto can't get the "Planet" title Damn you Neil deGrasse Tyson Pluto is and always well be a planet

what an odd hill to die on...

I see humor and sarcasm in 2020 is really dead...

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

#248

Post by rovolo »

coolgeek wrote: post #235
shadowprofile77 wrote: post #218

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

I don't know what the criteria are for defining a planet (and I know that there is a great deal of controversy), but "rounded by its own gravity" seems like a good dividing line to me.

That is half of the criteria the IAU decided defined a planet. The problem is that our moon is rounded by its own gravity and would be classified as a planet under that just criterion.

The other half is meant to exclude moons from the 'planet' definition: the body must 'clear' the neighborhood around its orbit. The Earth is in the same solar orbit as our moon but is much more massive, thus our moon doesn't count as a planet. Pluto doesn't meet this criterion because its orbit intersects with Neptune's orbit, and Neptune is much more massive.

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

#249

Post by baggy_trough »

ojnabieoot wrote: post #85
baggy_trough wrote: post #11

Earlier quoted context omitted.

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.

The maximum surface temperature on Ceres is -118C. How would you get to -20C without geological heating?

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

#250

Post by clarkmoody »

rbanffy wrote: post #188
clarkmoody wrote: post #109

Earlier quoted context omitted.

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)

I see what you did there...

Also, the book does describe a character's apprehension at climbing to the dizzying heights of a few millimeters off the surface.

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