News From Pluto: Clouds on Pluto, Landslides on Charon

By the end of this week, all the data gathered by the New Horizons spacecraft during its July 2015 flyby of the Pluto system will have finished downloading to Earth and be in the hands of the science team. Bonnie Buratti, a science team co-investigator said they have gone from being able to look at the pretty pictures to doing the hard work required to study the data. During today’s press briefing from the Division of Planetary Sciences conference, the New Horizons team shared a few interesting and curious findings they’ve found in the data so far.

While the famous global view of Pluto appears to show a cloud-free dwarf planet, Principal investigator Alan Stern said the team has now take a closer look and found handful of potential clouds in images taken with New Horizons’ cameras.

“Clouds are common in the atmospheres of the solar system,” Stern said during the briefing, “ and a natural question was whether Pluto, with a nitrogen atmosphere, has any clouds.”

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New Horizons Constraints on Charon's Present Day Atmosphere

New Horizons Constraints on Charon's Present Day Atmosphere

Authors:

Stern et al

Abstract:

We report on a variety of standard techniques used by New Horizons including a solar ultraviolet occultation, ultraviolet airglow observations, and high-phase look-back particulate search imaging to search for an atmosphere around Pluto's large moon Charon during its flyby in July 2015. Analyzing these datasets, no evidence for a present day atmosphere has been found for 14 potential atomic and molecular species, all of which are now constrained to have pressures below 0.3 nanobar, as we describe below, these are much more stringent upper limits than the previously available 15-110 nanobar constraints (e.g., Sicardy et al. 2006); for example, we find a 3σ upper limit for an N2 atmosphere on Charon is 4.2 picobars and a 3σ upper limit for the brightness of any atmospheric haze on Charon of I/F=2.6x10−5. A radio occultation search for an atmosphere around Charon was also conducted by New Horizons but will be published separately by other authors.

Charon's Argo Chasm is 185 Miles Long & Up to 5.5 Miles Deep

The Grand Canyon on Earth might feel a little inadequate if it ever learns about Argo Chasma on Pluto's moon Charon. Charon is home to a canyon 185 miles (300 kilometers) long and up to 5.5 miles (9 kilometers) deep in places. NASA says Argo Chasma also has one of the tallest known cliff faces in the entire solar system.

Scientists are working with images and data from the New Horizons spacecraft, which launched in 2006 and reached dwarf planet Pluto in 2015. Compared to the Grand Canyon in the US, Argo Chasma is five times deeper and 150 miles (240 kilometers) longer. Imagine the sheer terror of looking down if someone ever builds an Argo Chasma Skywalk with a glass floor.

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Evidence From the Small Moons of Pluto That Charon Formed From a Theia-like Impact With Pluto

The Small Satellites of Pluto as Observed by New Horizons

Authors:

Weaver et al

Abstract:

The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of ≈40 km for Nix and Hydra and ~10 km for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of ≈2. All four moons have high albedos ( ≈50-90 %) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages ≳ 4 Ga. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.

Surface compositions across Pluto and Charon

Surface compositions across Pluto and Charon

Authors:

Grundy et al

Abstract:

The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Pluto’s surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Pluto’s water ice “bedrock” was also mapped, with isolated outcrops occurring in a variety of settings. Pluto’s surface exhibits complex regional color diversity associated with its distinct provinces. Charon’s color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charon’s near-infrared spectra reveal highly localized areas with strong ammonia absorption tied to small craters with relatively fresh-appearing impact ejecta.

The geology of Pluto and Charon through the eyes of New Horizons

The geology of Pluto and Charon through the eyes of New Horizons

Authors:

Moore et al

Abstract:

NASA’s New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto’s encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.

The small satellites of Pluto as observed by New Horizons

The small satellites of Pluto as observed by New Horizons

Authors:

Weaver et al

Abstract:

The New Horizons mission has provided resolved measurements of Pluto’s moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of ~40 kilometers for Nix and Hydra and ~10 kilometers for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of ~2. All four moons have high albedos (~50 to 90%) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages of at least 4 billion years. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.

The Contraction/Expansion History of Charon with implication for its Planetary Scale Tectonic Belt

The Contraction/Expansion History of Charon with implication for its Planetary Scale Tectonic Belt

Authors:

Malamud et al

Abstract:

The New-Horizons mission to the Kuiper Belt has recently revealed intriguing features on the surface of Charon, including a network of chasmata, cutting across or around a series of high topography features, conjoining to form a belt. It is proposed that this tectonic belt is a consequence of contraction/expansion episodes in the moon's evolution associated particularly with compaction, differentiation and geophysical reactions of the interior. The proposed scenario involves no need for solidification of a vast subsurface ocean and/or a warm initial state. This scenario is based on a new, detailed thermo-physical evolution model of Charon that includes multiple processes. According to the model, Charon experiences two contraction/expansion episodes in its history that may provide the proper environment for the formation of the tectonic belt. This outcome remains qualitatively the same even if we assume a different initial composition and mass. Two alternative explanations for the precise localization and orientation of Charon's tectonic belt are speculated.

Hadeology: Pluto's Geology, a SETI Talk

Charon Might Have had a Subsurface Ocean that Froze

Images from NASA’s New Horizons mission suggest that Pluto’s moon Charon once had a subsurface ocean that has long since frozen and expanded, pushing outward and causing the moon’s surface to stretch and fracture on a massive scale.

The side of Pluto’s largest moon viewed by NASA’s passing New Horizons spacecraft in July 2015 is characterized by a system of “pull apart” tectonic faults, which are expressed as ridges, scarps and valleys—the latter sometimes reaching more than 4 miles (6.5 kilometers) deep. Charon’s tectonic landscape shows that, somehow, the moon expanded in its past, and – like Bruce Banner tearing his shirt as he becomes the Incredible Hulk – Charon’s surface fractured as it stretched.

The outer layer of Charon is primarily water ice. This layer was kept warm when Charon was young by heat provided by the decay of radioactive elements, as well as Charon’s own internal heat of formation. Scientists say Charon could have been warm enough to cause the water ice to melt deep down, creating a subsurface ocean. But as Charon cooled over time, this ocean would have frozen and expanded (as happens when water freezes), lifting the outermost layers of the moon and producing the massive chasms we see today.

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Pluto's Other Moons in a Family Portrait

The Dance of Pluto's Moons

The New Horizons mission is shedding new light on Pluto’s fascinating system of moons, and their unusual properties. For example, nearly every other moon in the solar system — including Earth’s moon — is in synchronous rotation, keeping one face toward the planet. This is not the case for Pluto’s small moons.

Pluto’s small lunar satellites are spinning much faster, with Hydra — its most distant moon — rotating an unprecedented 89 times during a single lap around the planet. Scientists believe these spin rates may be variable because Charon exerts a strong torque that prevents each small moon from settling down into synchronous rotation.

Another oddity of Pluto’s moons: scientists expected the satellites would wobble, but not to such a degree.

Pluto’s moons behave like spinning tops,” said co-investigator Mark Showalter of the SETI Institute in Mountain View, California.

Images of Pluto’s four smallest satellites also indicate several of them could be the results of mergers of two or more moons.

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Pluto and Charon may Have Iron Cores

Internal structure of Pluto and Charon with an iron core

Author:

Aitta

Abstract:

Pluto has been observed by the New Horizons space probe to have some relatively fresh ice on the old ices covering most of the surface. Pluto was thought to consist of only a rocky core below the ice. Here I show that Pluto can have an iron core, as can also its companion Charon, which has recently been modelled to have one. The presence of an iron core means the giant impact origin calculations should be redone to include iron and thus higher temperatures. An iron core leads to the possibility of a different geology. An originally molten core becomes solid later, with contraction and a release of latent heat. The space vacated allows the upper rock layers to flow downwards at some locations at the surface of the core, and some of the ice above the rock to descend, filling the spaces left by the rock motion downwards. These phenomena can lead to the forces recently deforming the icy surface of Pluto, and in a lesser way, of Charon.

Charon's Stunning Canyonlands

Say Hullo to Gorgeous Detailed Charon

An Amazing Flyover of Charon

New Gorgeous Picture of Charon

Fly by Pluto With New Horizons!

call and call back.  tag and tag back. 

Charon's "Geography" Gets Tentative Names, too

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To be honest, I'm even less thrilled with this.

Pluto's Potato Moons: Hydra and (pink) Nix

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