Europa's Acid Ice Fields

tr0llb4rt0 writes "The New Scientist reports on recent observations that suggest the ice on Jupiter's moon Europa may be highly acid with a pH of near zero, and have a surface layer of hydrogen peroxide. Two theories have been put forward. One says that the acid has been formed at the surface layer from oceanic salts reacting with the intense radiation from Jupiter, the other that sulphuric acid is coming directly from the ocean, with the water reacting with sulphur produced from undersea volcanos. Wilst reducing the chances of life on Europa, it is not ruling it out completely, as there are terrestrial extremophile bacteria which thrive in highly acid environments."

Comments

Dictionaries rule (www.m-w.com)

[jeblucas]

No.

Main Entry: 1acid
Pronunciation: 'a-s&d
Function: adjective
Etymology: French or Latin; French acide, from Latin acidus, from acEre to be sour -- more at ACET-
2 a : of, relating to, or being an acid; also : having the reactions or characteristics of an acid (acid soil) (an acid solution) b of salts and esters : derived by partial exchange of replaceable hydrogen (acid sodium carbonate NaHCO3) c : containing or involving the use of an acid (as in manufacture) d : marked by or resulting from an abnormally high concentration of acid (acid indigestion)

Volcanoes on Io responsible

[TasosF]

Sulfuric acid found on Europa was reported as far back as 1999 when this article was published on Science@NASA based on this NASA Press release. According to the article, sulfur from volcanoes on Io, another one of Jupiter's satellites, may be responsible for the environment on Europa.

Re:Acid ? pH zero ?

[sbennett]

pH 7 is neutral. 14 is 'completely' alkaline, and 0 is completely acid. pH 1 or 2 is a fairly strong acid (concentrated hydrochloric acid, for example).

Re:You know, I'd never throught of that

[DR SoB]

Ph 14 would be the opposite of Ph 0. It is considered the most extreme side of the BASIC scale (opposite of the ACID side). It does exist, but the original poster was wrong in what he thought was the scale..

The scale goes:

Ph0 - Most acidic Ph7 - Neutral Ph14 - Most Basic

Ph0 Ph7 Ph14

Acid Neutral Basic

pH of near zero?

[niom]

pH is a logarithmic measure. Saying "A pH of near zero" is like saying "a near infinite number of people" i.e. nonsense.

Re:pH of near zero?

[pclminion]

pH is a logarithmic measure. Saying "A pH of near zero" is like saying "a near infinite number of people" i.e. nonsense.

How so? pH = -log10([H+]) -- negative base ten log of hydrogen ion concentration. A pH of 0 would imply:

pH = 0 = -log10([H+]) ==> [H+] = 1 mol/liter.

H+ solutions which are more concentrated than 1 mol/liter will have pH values below zero.

A "logarithmic scale" means that linear changes in the scale indicate exponential changes in some underlying quantity. For every change of 1 in pH number, the concentration of the solution changes by a factor of ten. Just because the graph of log(x) goes to minus infinity as x goes to zero doesn't mean a logarithmic scale has some kind of asymptote.

Learn before you post.

pH meaning

[Walkiry]

The pH is the negative of the base 10 logarithm of the H3O+ ion concentration in water. At any given point, the pH + pOH = 14, and both the pH and pOH of neutral water are 7.

Re:Acid ? pH zero ?

[AJWM]

What scientific illiterate modded this "insightful"?

The pH scale runs from 0 to 14, with a pH of 7 being neutral. The number is actually an inverse exponent and has to do with the concentration of hydrogen ions (H+) in solution. (You could also use pOH, relating to the concentration of hydronium ions (OH-), the relationship is pOH = 14 - pH).

Re:Acid ? pH zero ?

[LouisZepher]

IIRC, I think there's two scales for pH. One states that 1-4.9 is "base", 5 is neutral 6-10 is "acid". The other is 0-5 "acid", 6-10 "alkaline".

Confused the hell out of me in Bio class when the chart in the textbook was different from the charts the teacher was using on the OH lecture. Then again, it's been a few years, so I may be wrong.

And a monopropellant to boot

[Spamalamadingdong]

I was thinking the same thing. H2O2 is not a particularly powerful (high-impulse) fuel, but if you could refine it you could use it as a source of energy to make something more potent (LH2 and LOX). It would also be a great way of running a self-powered rover/hopper; if it came to a crevasse or other impassable feature, it could use rocket power to jump over it.

This assumes that the concentration is high enough to be recovered and purified using the available local energy. That may not be the case.

Can't have two theories

[paiute]

Two theories have been put forward.

You cannot have two contradictory possible explanations and have them both be theories. What you have are two hypotheses.

The hypothesis that fits with the evidence might become a theory.

Re:Can't have two theories

[devilspgd]

Unless I'm mistaken, you can have two hypotheses which both fit the evidence. In the absence of further evidence, you have two valid theories (although ultimately at least one must be incorrect, or at a minimum incomplete)

Re:Acid ? pH zero ?

[forkboy]

Not quite. pH is a scale for dilute acids and bases. 1M HCl would have a pH of 0. I've gotten 1M on my hands before...it's not that bad. Concentrated HCl is in the negatives as far as the pH scale goes. (pH=-log[H+]) The H+ concentration would be the same as the acid concentration, in this case 13M. -log(13)=-1.11

Re:H2O2 indicates lots of OXYGEN!

[Walkiry]

It's called Catalase. It's an enzyme that is present in many living organisms and catalyzes the reaction 2H2O2 -> 2H2O + O2 . Plants have it too. In Europa, though, the reaction might be very slow unless there is a catalyst to help it.

So it really depends on how you define "usable", that is, what you really want to do with that oxygen peroxide ;)

Re:H2O2 indicates lots of OXYGEN!

[forkboy]

That's assuming the catalase (the enzyme responsible for converting the peroxide into O2 and water) can survive the acidic environment. Most protiens can't thrive in a pH that low....it screws up the hydrogen bonding resposible for the folding that gives it the characteristic shape of its function.

Re:With apologies to Monty Python...

[FroMan]

the strongest castle on this planet!

Ahem, moon, I believe.

Re:Acid ? pH zero ?

[MoP030]

close....
pH = -log([H+]), where [H+] is a usual way to denote the Proton/Hydrogen cation concentration. So for pH 7 we have the natural concentration of 10e-7 mol/l of H+. The pH may however be larger than 14 for very strong bases and smaller than 0 for strong acids. For the latter case, it simply means that [H+]>1 mol/l. Concentrated hydrochloric acid has a negative pH e.g.
Also, Hydronium ions are hydratized H+, H30+, while OH- are called hydroxide ions.

Re:Alternative life forms

[eggstasy]

What a load of bull. Are you on crack? You're sitting in a HUGE BALL OF SILICON COMPOUNDS.
Every rock on earth is based on silicon, for crying out loud, there is absolutely no shortage of it.

Limit, yes

[yet another coward]

There is a limit to pH, but it is not so hard and fast. Since pH refers to concentration in water, it is possible to displace more and more of the water with acid solute. There should be either a limit of solubility for the solute or a notion of all solute, no water that limits the extreme of pH for a given solute.

I'm a bit suspicious about this...

[Mark_in_Brazil]

The article presents three hypotheses for how sulfuric acid might get into Europa's oceans. The first is that Io ejects it, and it ends up falling onto Europa. Another is that precursor salts are present in Europa's ocean and intense radiation converts them into acid. The third is the one that leaves me a bit suspicious. From the article:

Jeff Kargel of the US Geological Survey in Flagstaff, Arizona, believes the sulphuric acid is coming directly from the ocean. He thinks that Europa's heart is rocky, with undersea volcanoes releasing sulphur-containing compounds and oxygen that react with the ocean water to form sulphuric acid.

"Europa has an Io hiding underneath the ocean," he says. If the surface sulphates have come from the water deep below, Europa's ocean might be an "acidic sulphate brine".

The bit I put in boldface is suspicious. Io is volcanic because of the effects of it moving through Jupiter's inhomogeneous gravitational field, which causes stresses that are sufficient to heat up and melt Io's interior, creating the conditions for volcanoes. This effect was predicted by Professor Stanton Peale of the University of California, Santa Barbara just before Voyager arrived and took pictures of Io. But Professor Peale ran the same calculation for all the moons in the solar system, and the only one that came up as possibly volcanic was Io.

Interesting aside: Professor Peale narrowly made the window before Voyager took the now-famous pictures. He had done some work earlier on Earth's moon, then applied the same calculation to every moon in the solar system. But for historical reasons, orbital data about the Galilean moons are recorded differently from those of every other moon in the book where Professor Peale looked up the numbers to check each moon. He only noticed this months later, and when the calculation showed the possibility of a volcanic Io, he had to rush to try to get his prediction published-- ANYONE can write a paper explaining why a given moon is volcanic, but Professor Peale had actually predicted that Io was volcanic before anyone knew if it really was.

Anyway, the idea that Europa has a rocky center (with a molten interior) doesn't seem very likely to me. I've sent an e-mail to Professor Peale asking what he thinks, but I just did that, and he has not replied yet.

--Mark

Re:Alternative life forms

[Daetrin]

The presence of molecular oxygen, O2, is a result of the presence of life. The presence of atomic oxygen, in whatever form, is a prerequisite for life, at least of the kind found on Earth.

The oxygen was here long before life, it was just locked up in other chemical compounds besides O2.

Re:Mental Note...

[Muhammar]

1. Stainless steel is probably good enuf, especialy at freezing temperatures at Europa
2. It actualy rains sulfuric acid on Venus and the surface temperature is 350C there (and 90 atm pressure). Russians managed in sixties, although their probes did not last much over 1 hour before malfunction.