
Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds - grawprog
https://www.theguardian.com/science/2020/aug/10/planet-ceres-ocean-world-sea-water-beneath-surface
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shadowprofile77
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.

~~~
saalweachter
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, "Oh, they must be talking about the largest
asteroid/eighth largest known dwarf planet", but adding "planet" makes it
clear that we're talking about space stuff.

~~~
alehul
Here's a Euler diagram on planets, dwarf planets, minor planets, so on and so
forth from Wikipedia [1].

Alan Stern, who coined the term "dwarf planet," initially wanted it to be
under the umbrella of planet as a distinct subtype. [2]

The International Astronomical Union (IAU), however, believed that what we
call a dwarf planet — it was referred to as a planetoid — should _not_ be
considered a type of planet.

The IAU later held a session where they decided to use the term dwarf planets
in place of planetoids, however they decided that a dwarf planet is not a type
of planet.

It's semantically inconsistent, but that's where we stand right now per the
IAU.

[1]
[https://upload.wikimedia.org/wikipedia/commons/f/fc/Euler_di...](https://upload.wikimedia.org/wikipedia/commons/f/fc/Euler_diagram_of_solar_system_bodies.svg)
[2]
[https://en.wikipedia.org/wiki/Dwarf_planet](https://en.wikipedia.org/wiki/Dwarf_planet)

------
gaukes
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).

~~~
toshk
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?

~~~
at_a_remove
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 can make molecules
with two atoms, but no _chains_. If you have two slots open, you can make a
chain, but little else. Although try making a chain of oxygen -- even the
three-link ozone is not particularly stable. Carbon can have four different
bonds going at once, which is pretty crazy, and so you want something with
three or four slots available.

But then you say, well, silicon could have four. And it _could_ ... but for
the fact that it is so huge by comparison to carbon (that whole other
"electron shell") that it rarely has analogues to organic (carbon-based)
compounds. Also, it doesn't like to do much until you get it fairly hot. So
you climb back up a row and it looks like carbon, nitrogen, boron ... those
are going to do your heavy lifting when you need multiple bonds, with
hydrogen, oxygen, and the halogens or alkali metals somewhere on the outside.
Hence _carbon chauvinism_. Carbon is something like the fourth most common
element in the universe after all.

Then you start talking about solvents -- all of this stuff has to slosh around
in _something_ after all, your chemistry experiments take place in liquids --
and the field is a bit wider but dang, water has some crazy properties that
make it quite a catch when it comes to solvents.

You've got temperature ranges: down in the single digits of Kelvin you're not
going to have much chemistry happening, and up in the thousands of Kelvins
even iron boils and then again, no more structure.

Once you start looking for these various "sweet spots" it all comes down to
finding a place where you can have liquids (your solvent), solids (for
structure), and gases (even if they are dissolved in liquids). Combine that
with the more common elements (especially those that are friendly to complex
chemistry) and you have something not entirely un-Earthlike.

There's tons of Wikipedia articles on it, but ... the restrictions of
chemistry are the bulk of the culprit, I'm afraid.

~~~
henearkr
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.

~~~
Balgair
That neutron star story is _wild_. Hard recommendation to read.

One point I have with Baxter is that his premises are just bananas, but the
people acting in them are pretty recognizable. To be fair, if the characters
were also nutter-butter, no one would read it, as it wouldn't be a story
anymore, just a strangely formatted research paper.

[https://en.wikipedia.org/wiki/Flux_(novel)](https://en.wikipedia.org/wiki/Flux_\(novel\))

~~~
gizmo686
For another life on neutron star: Dragons Egg, Robert L. Forward

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

~~~
shakna
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](http://dx.doi.org/10.1126/science.1253358)

~~~
marcusverus
>They conclude that the mantle transition zone--410 to 660 km below the
Earth's surface--acts as a large reservoir of water.

Sadly there will be no eyeless space whales in our basement, given that the
temperature at that depth on Earth is around 2,000° Celsius.

~~~
JohnBooty
_eyeless FIRE whales_

~~~
ColeyG
I like this line of thinking way better lol

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ncmncm
My first awareness of Ceres was from an article by Isaac Asimov titled, "The
World Ceres". (Say it out loud.)

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Animats
Ceres is a good place for a lander and rover then. Might be some action there.
Face it, Luna and Mars are boring, low-value real estate.

~~~
vmception
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.

~~~
randomdude402
I thought the atmosphere was mostly carbon dioxide and sulfuric acid. What
makes it potentially high value?

~~~
ncmncm
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.

~~~
valuearb
it is extremely unlikely that humans can’t live on a Mars, in suitable
habitats. One third gee is far closer to one gee in effect than it is zero
gee.

~~~
azernik
This is _possible_ , but we don't actually _know_ for sure. Only in the last
few years has there been hardware on the ISS capable of creating partial-g for
rodents [1], and so far (in published research, at least) it hasn't been used
for anything except 1g.

[1]
[https://www.nature.com/articles/s41598-017-10998-4](https://www.nature.com/articles/s41598-017-10998-4)

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colordrops
It's not a planet is it? If Pluto is not a planet, Ceres certainly is not
either.

~~~
ceejayoz
The first paragraph uses the term “dwarf planet”.

[https://en.wikipedia.org/wiki/Dwarf_planet](https://en.wikipedia.org/wiki/Dwarf_planet)

~~~
overflow_error
yeah but dwarf planet is not a planet, this is like saying method is a
function, outrageous

~~~
Twisol
If that bothers you, you'll _love_ the nLab's page on the red herring
principle :)

> The mathematical red herring principle is the principle that in mathematics,
> a “red herring” need not, in general, be either red or a herring.

> Frequently, in fact, it is conversely true that all herrings are red
> herrings. This often leads to mathematicians speaking of “non-red herrings,”
> and sometimes even to a redefinition of “herring” to include both the red
> and non-red versions.

[https://ncatlab.org/nlab/show/red+herring+principle](https://ncatlab.org/nlab/show/red+herring+principle)

~~~
zajio1am
Well, i usually use 'soy meat' example, which is obviously not meat. The case
where adjective moves meaning outside of boundaries of original meaning,
instead of just making it more precise, is kind of perverse. Perhaps people
should use hyphen to make it one term in cases where the meaning is not result
of composition (e.g. 'dwarf-planet' and 'soy-meat' vs. 'big planet' and 'pork
meat').

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sgt
I can see NASA releasing some "Visions of the Future" new posters for Ceres:

"Take your first scuba diving lessons on Ceres"

"Swim with the briny undersea monsters of Ceres"

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TheRealNGenius
Thought this was about another planet elsewhere, didn’t realize they were
referring to the dwarf planet

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stx
Is this actually H2O water? I read the article but I am still unclear.

I am often excited to hear that water was discovered on some planet or moon
but its always a disappointment to learn that its liquid methane or some other
liquid that is not actually H2O water.

~~~
renewiltord
What other kind of substance is called 'water'? As far as I know only H2O is
described as water.

~~~
edgyquant
Water usually means liquid H2O. Europa, for instance, isn't liquid water but
ice that is squeezed and loosened to the point it acts like a liquid while
still being well below freezing and basically just ice sand

~~~
renewiltord
Very cool!

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outworlder
There goes the water rationing narrative in The Expanse...

~~~
Cyphase
Nah, kopeng mi; inyalowda, dey stole da owkwa from beltalowda!

~~~
bloopernova
Miller to Diogo: "Don't mess wit de owkwa!"

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JackFr
Owkwa beltalowda!

~~~
outworlder
Lots of water. No Cant to remember.

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acd
Very interesting observations!

I think many planets may have life below the surface. The hot core of planets
behave like a heat reactor. Somewhere between the hot planet core and cold
planet surface there should be a balanced temperature a mix. That mix may have
a temperature of 0-37C.

[https://en.m.wikipedia.org/wiki/Planetary_core](https://en.m.wikipedia.org/wiki/Planetary_core)

~~~
Chris2048
We should be able to do the same on earth first. Where's our underground Polar
habitats? I personally see Musks' Boring company" stuff as interesting as the
rockets, I wish it where cheaper to build cities/tunnels underground.

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mrfusion
What provides the heat to keep it liquid?

~~~
ncmncm
Has to be radioactives. Mainly, though, miles of ice makes a pretty good
insulator.

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FailMore
This is f __king awesome!

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interfixus
> _Ceres is the largest object in the asteroid belt between Mars and Jupiter
> and has its own gravity, enabling the Nasa Dawn spacecraft to capture high-
> resolution images of its surface_

Scratching my head. Trying as I may. But not making sense.

[insert subthread about Gell-Mann amnesia here]

~~~
mxcrossb
I was confused by this too. I wonder if it means that the spacecraft was able
to enter into its orbit and circle around taking pictures, as opposed to one
pass by

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tus88
I wonder what kind of buglife lives down in the depths.

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abledon
spaceX when? 2048?

~~~
elliekelly
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 the constraining factor for faster space travel? Safety? Fuel?
Hardware? Technology? If Elon was going to spend every penny he has to get to
Ceres as fast as possible, how would his billions best be spent?

~~~
dmurray
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 to send a spaceship there.

Here's a map of the solar system by delta-V [0]. Good news is it's roughly
equally difficult to get to Ceres as to get to Mars! It's further away, but
it's smaller which means less decelerating when you get there.

For your actual question...you can get faster routes with more fuel. We're
pretty close to the limits of how big a rocket we know how to build and still
get it to Mars (or Ceres) with a 2-ton payload (enough for a lander, a rover
and a little fuel) using the most fuel-efficient route. If you want to get
there faster, which might be important for manned missions, you need a smaller
payload or a bigger rocket. Or the most likely solution - you launch lots of
rockets and join up the payloads into a bigger spaceship in Earth orbit. If
Elon's goal was to make a one-way trip to Ceres as fast as possible, he'd be
doing mostly the same as he is now - focusing on being able to build lots of
rockets and launch them cheaply.

[0] [https://imgur.com/WGOy3qT](https://imgur.com/WGOy3qT)

~~~
dc443
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.

~~~
dmurray
Yes for a flyby or orbital mission. I was thinking of a landing mission which
costs more delta-V. In practice, you can get that delta-V by aerobraking when
going to Mars but not to Ceres, though on the other hand you need to build the
spacecraft to withstand the Mars atmosphere. So maybe the answer is "it's
complicated" but either way it's reasonably close, not the 5x further you
might think from looking at the closest approaches of the orbits of Earth,
Mars and Ceres.

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arkanciscan
Great news for colonies! All the water and table salt they need! Just have to
watch out for Pokeshells...

~~~
arkanciscan
Not one Oni player in the room? Y'all need to get out more.

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sago
All these worlds are yours except Ceres. Use them together. Use them in peace.

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hinkley
> Dwarf planet, believed to be a barren space rock, has an ‘extensive
> reservoir’ of brine beneath its surface, images show

Believed by who? We already knew it was made substantially of ice. Isn't this
just discovering that some of it is liquid?

Wikipedia quotes a PDF from 2017 regarding the quantity of ice, and by then
the fact of Ceres having so much ice had already been worked into the story
line of The Expanse.

~~~
mr_toad
Previously it was thought to be mostly frozen and hydrated minerals (mud),
without any substantial oceans.

