Tiny Pluto Big On Frozen Water Reserves

New submitter rmdingler writes that a new map created by NASA based on the New Horizons flyby of Pluto "shows much more frozen water than scientists initially expected." Using LEISA to photograph from 108,000 kilometers away, much more of the recently demoted planet's frozen surface liquid is water, rather than methane, carbon monoxide, and nitrogen as originally posited.

Comments

Amazing that it is not buried

[jfdavis668]

Water freezes at a much higher temperature than many of the other compounds. You think it would have frozen first and be buried under everything else. Some action must bring it back up and deposit it on the surface.

Re:Amazing that it is not buried

[Rei]

The summary is lousy. It's not "much less water ice than thought", it's much less "than was previously known". It had been hard to detect the water ice through the frosts previously.

It's always been expected that a large portion of Pluto's mass is water ice. Also, it was well known before NH arrived that any surface topography of significance would have to be from water ice, as the other ices are just too "soft" to hold up strong contours.

As for water ice being buried, why would you expect that? Water ice is lighter than nitrogen and carbon monoxide ices. It basically "floats" on them. There seems to be a sort of N2/CO/CH4 "mantle" which is exposed to the surface (and convecting) at Sputnik (the point nearest Charon). Elsewhere, however, a water ice crust floats atop it, seemingly progressively thicker the further one gets from Sputnik/Charon.

I find it interesting - perhaps coincidental, perhaps not - that Pluto is like our moon, with a crust thinner and more geologically active on the side of which it's tidally locked to its partner, and thicker/less active on the opposite side. If we can figure out Pluto's dynamics better, it might help us understand our own moon better.

Pluto is a beautifully, fascinatingly weird place. There's some good evidence that entire water-ice floating mountains have washed ashore and collected on the shores of Sputnik - perhaps water ice from the deep depths. Certainly there are shorelines that have this appearance today, and we can see smaller water-ice chunks floating and stuck between the roiling convection cells. If one pictures rolling back the clock, Pluto started out very hot (alternatively with multiple periods of heat, such as during the formation and/or capture of Charon). The first things to condense out would have been rocks, such as silicates, with a water ice ocean and a nitrogen/methane/CO atmosphere. Then the water ice would have frozen. Then the gases would have frozen atop it. But then you have a situation where you have an extensive heavier layer over an even more extensive, lighter layer. So there may be potential for cycling. But it's hard to say, because different crystal forms in different temperature and pressure conditions have different densities.

Charon also has a look of large chunks of water ice drifting around. But while Pluto has its active mantle exposed to space, Charon seems frozen in time. You can see structures that look like massive islands (or even continents) that have broken off from each other, drifted, then became frozen into place. And there's some crazy-massive rifting, as if some layers changed dramatically in size relative to others as they froze (Pluto too has rifting, but Charon's rifts are even more spectacular)

Consumables

[Applehu Akbar]

In space we seem to be finding water, water everywhere. And hydrocarbons, popping up in the most unexpected parts of the solar system. By the time our robots have mapped everything out, there won't be anything we will need to haul up from the terrestrial gravity well besides ourselves and the first iteration of tools-to-make-the-tools.

Re:Consumables

[rgmoore]

It shouldn't be that surprising to see water and methane everywhere. After all, hydrogen is by far the most common element in the universe, and oxygen and carbon are also relatively common. Simple compounds of heavier elements with hydrogen should be among the most common things to see on planets (and dwarf planets and moons) that don't have strong enough gravity to keep hydrogen in their atmosphere.

Re:Consumables

[Rei]

We've known that water is one of the most common components of the universe, and the most dominant compound of the outer solar system, for over a century.

Re:Consumables

[thinkwaitfast]

tools-to-make-the-tools

humans got to today's level of technology starting with sticks and rocks for tools. The big jump however came with the lathe. Using a lathe, you can either build any tool known to man or the tool used to build any known tool known to man (a wafer processing machine for example). You can even construct a first lathe using nothing more than some hand tools and a drill.

Just to clarify this

[NotSoHeavyD3]

Current understanding is that matter is under 5% of the universe and the vast majority of that is hydrogen. from Wikipedia on hydrogen

Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.

The vast majority of the universe is thought to be composed of dark energy and dark matter, whatever those are.

Hydrogen and Dark matter

[XXongo]

After all, hydrogen is by far the most common element in the universe, and oxygen and carbon are also relatively common.

Hydrogen is only around 3% of the universe, and growing scarcer all the time.

Two different things. Hydrogen comprises 75% by mass of the elements in the universe. http://www.webelements.com/per...

If you are saying it's only 3% of the universe, you must be including dark matter. But that's not an element.

Planets don't, in general, contain dark matter, so the abundance of hydrogen relative to dark matter isn't really relevant to the amount of water found on Pluto and other solar system objects.

Re:Water

[Rei]

The summary is wrong. There is no surprise about how much water ice Pluto has, it's always been expected that it's predominantly water ice.

The actual article linked says that the maps show more water ice than was previously known, not than previously thought. It's hard to see through the surface frosts to see the water ice. Mountains are impossible on Pluto without water ice (or other high compressive strength material - aka, not N2, CH4, CO, etc). The instant mountains were seen, we knew that the crust was mostly water ice. And even before then, we knew that - regardless of what its crust was made of - that Pluto is in large part water ice, due to its density (1,86g/cm3).