Scientists study nitrogen provision for Pluto's atmosphere

August 11, 2015, Southwest Research Institute
Scientists at Southwest Research Institute are studying New Horizons data to discover what’s pumping up the nitrogen in Pluto’s atmosphere, even as it escapes into interplanetary space. This enhanced color image of the dwarf planet helps scientists detect differences in the composition and texture of Pluto’s surface. The data hint that Pluto may still be geologically active, a theory that could explain how Pluto’s escaping atmosphere remains flush with nitrogen. Credit: NASA/JHUAPL/SwRI

The latest data from NASA's New Horizons spacecraft reveal diverse features on Pluto's surface and an atmosphere dominated by nitrogen gas. However, Pluto's small mass allows hundreds of tons of atmospheric nitrogen to escape into space each hour.

So where does all this nitrogen come from? Dr. Kelsi Singer, a postdoctoral researcher at Southwest Research Institute, and her mentor Dr. Alan Stern, SwRI associate vice president and the science lead for the New Horizons mission, outlined likely sources in a paper titled, "On the Provenance of Pluto's Nitrogen." The Astrophysical Journal Letters accepted the paper for publication on July 15, just a day after the spacecraft's closest encounter with the icy dwarf planet (ApJ, 808, L50).

"More nitrogen has to come from somewhere to resupply both the nitrogen ice that is moving around Pluto's surface in seasonal cycles, and the nitrogen that is escaping off the top of the atmosphere as the result of heating by ultraviolet light from the Sun," said Singer. They looked at a number of different ways that nitrogen might be resupplied.

Singer and Stern wondered if comets could deliver enough nitrogen to Pluto's surface to resupply what is escaping its atmosphere. They also looked at whether craters made by the comets hitting the surface could excavate enough nitrogen - but that would require a very deep layer of nitrogen ice at the surface, which is not proven. The team also studied whether craters could expose more surface area, by punching through surface deposits that would likely be built up over time.

"We found that all of these effects, which are the major ones from cratering, do not seem to supply enough nitrogen to supply the escaping atmosphere over time," continued Singer. "While it's possible that the escape rate was not as high in the past as it is now, we think geologic activity is helping out by bringing nitrogen up from Pluto's interior."

And while the data weren't in before this paper was written, the newest images of Pluto show land forms that suggest heat is rising beneath the surface, with troughs of dark matter either collecting, or bubbling up, between flat segments of crust, which could be related.

"Our pre-flyby prediction, made when we submitted the paper, is that it's most likely that Pluto is actively resupplying from its interior to its surface, possibly meaning the presence of ongoing geysers or cryovolcanism," said Stern. "As data from New Horizons comes in, we will be very interested to see if this proves true."

New Horizons is part of NASA's New Frontiers Program, managed by the agency's Marshall Space Flight Center in Huntsville, Ala. The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., designed, built, and operates the New Horizons spacecraft and manages the mission for NASA's Science Mission Directorate. SwRI leads the science mission, payload operations, and encounter science planning.

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mreda14
1 / 5 (2) Aug 11, 2015
When helium is cooled to a critical temperature of 2.17 K (called its lambda point), a remarkable discontinuity in heat capacity occurs, the liquid density drops, and a fraction of the liquid becomes a zero viscosity "superfluid". Onnes received the Nobel Prize in 1913 for his low temperature work leading to this achievement. Well deep inside Pluto surface, liquid nitrogen might behaves as superfluid. Flows upward with zero viscosity ( no friction at all). I am not sure if this might explain anything.
mreda14
1 / 5 (2) Aug 11, 2015
When helium is cooled to a critical temperature of 2.17 K (called its lambda point), a remarkable discontinuity in heat capacity occurs, the liquid density drops, and a fraction of the liquid becomes a zero viscosity "superfluid". Onnes received the Nobel Prize in 1913 for his low temperature work leading to this achievement. Well deep inside Pluto surface, liquid nitrogen might behaves as superfluid. Flows upward with zero viscosity ( no friction at all). I am not sure if this might explain anything.
mreda14
1 / 5 (2) Aug 11, 2015
As the superfluid nitrogen flows upward. Higher temperature make the nitrogen lose the superfluidity property. That is probably why nitrogen is not seen to evolve from the surface.
Steve 200mph Cruiz
not rated yet Aug 12, 2015
I wanna go back again
Torbjorn_Larsson_OM
not rated yet Aug 12, 2015
I don't think high pressure nitrogen becomes superfluid. It seems it becomes atomic and a semiconductor at half the pressure of Earth's core. [ http://news.scien...ts-bonds ]. I doubt Pluto's core achieve as much pressure.

More likely the putative inner "crustal" ocean of Pluto is a fact, and as an outer system body it has dissolved ammonia in it like how Titan is thought to have. That is then the nitrogen source.
katesisco
1 / 5 (1) Aug 12, 2015
Where did the nitrogen come from?
What I emailed Nick Lane after I read Oxygen 4 years ago.
I noted with interest that lithium thought missing is probably alloyed inside a stellar body reducing the need for high pressures thought necessary to produce LMH (liquid metallic hydrogen),
wduckss
2 / 5 (4) Aug 12, 2015
"However, Pluto's small mass allows hundreds of tons of atmospheric nitrogen to escape into space each hour."
Why atmosphere, did not run away with the Titan, Venus ...?

"Singer and Stern wondered if comets could deliver enough nitrogen to Pluto's surface to resupply what is escaping its atmosphere."
Why comets not deliver enough nitrogen to Mercury, Mars, Callisto, ...?
Uniformity gentlemen and ladies. Laws must be worth for all the bodies. Partial observation does not lead anywhere.
FredJose
1 / 5 (5) Aug 13, 2015
They looked at a number of different ways that nitrogen might be resupplied

it's most likely that Pluto is actively resupplying nitrogen from its interior to its surface, possibly meaning the presence of ongoing geysers or cryovolcanism

Stern will probably find that nitrogen is indeed coming up via the cryo-volcanism. So he can jump into the air and shout eureka!
The real problem for them [given that Pluto is so tiny] would be to explain how this could have been going on for a supposed 4.5 billion years since Pluto was born according to the accretion theory.
This is of course the real issue, even though it is not stated as succinctly or directly as that. The researchers are dancing around the issue but dare not state it in so many words because it would immediately call into question whether Pluto is indeed that old.
docile
Aug 13, 2015
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Vietvet
4 / 5 (5) Aug 13, 2015
dare not state it in so many words because it would immediately call into question whether Pluto is indeed that old.

@DavidJose

What you don't dare to say is that your religious beliefs trump scientific evidence.
docile
Aug 13, 2015
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docile
Aug 13, 2015
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JustAnotherGuy
not rated yet Aug 13, 2015
So we can consider the loss of ten nanometer layer of nitrogen ice per hour

By means of which process? The same loss rate along the 247.94 years duration orbital period?
Just to bring some from the >study (which) implies ""similar"" result<:
...(N2 lost) over 4 billion years. This is equivalent to a condensed global N2 surface layer on Pluto ∼0.3–3 km in depth

Perhaps posting so many comments don't let you enough time to read. There is much to read and properly understand, thus: "There is YET very much to solve"
Yet more, New Horizon's data is awaiting...

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