Naming the Mysterious Features of Pluto and Charon –“An Open Invitation to the World Community”

 

 

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In a few months, the Craters, mountains and other landforms of Pluto will take shape before our eyes. When New Horizons flies past Pluto in July, we will see a new, alien landscape in stark detail. At that point, we will have a lot to talk about. The only way we can talk about it is if those features, whatever they turn out to be, have names.


The SETI and the New Horizons team is beginning a campaign called “Our Pluto”. The goal is to gather together the names that they will eventually use to label the maps of Pluto and its large moon, Charon. After discussions with the International Astronomical Union (IAU), they have defined a set of broad themes for these names, related to mythology, literature and history.

"The New Horizons science team is doing something unprecedented," says SETI astronomer Mark Showwalter. "Naming campaigns have been held before, but on a different scale. Today, the entire landscapes of Pluto and Charon is open to the public. They have called the campaign “Our Pluto” because they think that everyone should have a say in the names we use on those strange and distant worlds. At ourpluto.seti.org, you can vote for your favorite names, talk about them, and nominate names that we might have overlooked."

After the campaign ends, the New Horizons science team will select your best ideas and pitch them to the IAU. The IAU will have final say over the names on the maps of Pluto and Charon.

Tops on the mission's science list are characterizing the global geology and topography of Pluto and its large moon Charon, mapping their surface compositions and temperatures, examining Pluto's atmospheric composition and structure, studying Pluto's smaller moons and searching for new moons and rings.

New Horizons' seven-instrument science payload, developed under direction of the Southwest Research Institute, includes advanced imaging infrared and ultraviolet spectrometers, a compact multicolor camera, a high-resolution telescopic camera, two powerful particle spectrometers, a space-dust detector (designed and built by students at the University of Colorado) and two radio-science experiments. The entire spacecraft, drawing electricity from a single radioisotope thermoelectric generator, operates on less power than a pair of 100-watt light bulbs.

Distant observations of the Pluto system began Jan. 15 and will continue until late July 2015; closest approach to Pluto is July 14.

“There is a real possibility that New Horizons will discover new moons and rings as well,” says Stern. Already, Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra. Numerical simulations show that meteoroids striking those satellites could send debris into orbit, forming a ring system that waxes and wanes over time in response to changes in bombardment. “We’re flying into the unknown,” says Stern, “and there is no telling what we might find. The encounter begins next January,” adds Stern. “We’re less than a year away.”

Other than a few indistinct markings seen from afar by Hubble, Pluto’s landscape is totally unexplored. Although some astronomers call Pluto a “dwarf” planet, Stern says there’s nothing small about it. “If you drove a car around the equator of Pluto, the odometer would rack up almost 5,000 miles—as far as from Manhattan to Moscow.” Such a traveler might encounter icy geysers, craters, clouds, mountain ranges, rilles and valleys, alongside alien landforms no one has ever imagined.

The closest approach is scheduled for July 2015 when New Horizons flies only 10,000 km from Pluto, but the spacecraft will be busy long before that date. The first step, in January 2015, is an intensive campaign of photography by the Long Range Reconnaissance Imager or “LORRI.” This will help mission controllers pinpoint Pluto's location, which is uncertain by a few thousand kilometers.

"LORRI will photograph the planet against known background star fields," explains Stern. "We’ll use the images to refine Pluto’s distance from the spacecraft, and then fire the engines to make any necessary corrections.”

By late April 2015, the approaching spacecraft will be taking pictures of Pluto that surpass the best images from Hubble. By closest approach in July 2015, a whole new world will open up to the spacecraft’s cameras. If New Horizons flew over Earth at the same altitude, it could see individual buildings and their shapes. The image above NASA space-artist Ron Miller's concept of geysers and sundogs on Pluto.

He likens New Horizons to Mariner 4, which flew past Mars in July 1965. At the time, many people on Earth, even some scientists, thought the Red Planet was a relatively gentle world, with water and vegetation friendly to life. Instead, Mariner 4 revealed a desiccated wasteland of haunting beauty. New Horizons’ flyby of Pluto will occur almost exactly 50 years after Mariner 4’s flyby of Mars—and it could shock observers just as much.

Although temperatures on Pluto's surface hover around -230 °C, but researchers have long wondered whether the dwarf planet might boast enough internal heat to sustain a liquid ocean under its icy exterior.

Guillaume Robuchon and Francis Nimmo at the University of California, Santa Cruz, have calculated that the presence of an ocean depends on two things: the amount of radioactive potassium in Pluto's rocky core, and the temperature of the ice that covers it.

Density measurements suggest a rocky core fills 40 per cent of the dwarf planet's volume. If the core contains potassium at a concentration of 75 parts per billion, its decay could produce enough heat to melt some of the overlying ice, which is made of a mixture of nitrogen and water.

It should have at least that much potassium and probably more, says William McKinnon at Washington University in St Louis, Missouri, who points out that Earth, which probably formed with less of the volatile element due to its closer distance to the sun, has 10 times that concentration in its core.

Heat from Pluto's core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting. If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team concluded.

The viscosity of the ice depends on the size of individual ice particles, with smaller grains flowing more easily. There is no way to measure this from Earth, but Pluto's shape could reveal evidence of an ocean, the team says. Pluto's spin is slowing down due to tugs from its large moon Charon. Fast-spinning objects bulge out at their equator, but a soft interior would allow the world to relax into more of a sphere as its spin slows down. NASA's New Horizons probe will image the dwarf planet's shape when it flies past in 2015.

"It's very exciting to think that the dwarf planets could have astrobiological potential," says Stern. In 2011, the highly sensitive Cosmic Origins Spectrograph aboard the Hubble Space Telescope discovered a strong ultraviolet-wavelength absorber on Pluto's surface, providing new evidence that points to the possibility of complex hydrocarbon and/or nitrile molecules lying on the surface, according to researchers from Southwest Research Institute and Nebraska Wesleyan University. These chemical species can be produced by the interaction of sunlight or cosmic rays with Pluto's known surface ices, including methane, carbon monoxide and nitrogen.

"This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color," said Stern.

The team also discovered evidence of changes in Pluto's ultraviolet spectrum compared to Hubble measurements from the 1990s. The changes may be related to differing terrains seen now versus in the 1990s, or to other effects, such as changes in the surface related to a steep increase in the pressure of Pluto's atmosphere during that same time span.

Heat from Pluto's core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting. If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team concluded.

Tops on the mission's science list are characterizing the global geology and topography of Pluto and its large moon Charon, mapping their surface compositions and temperatures, examining Pluto's atmospheric composition and structure, studying Pluto's smaller moons and searching for new moons and rings.

New Horizons' seven-instrument science payload, developed under direction of the Southwest Research Institute, includes advanced imaging infrared and ultraviolet spectrometers, a compact multicolor camera, a high-resolution telescopic camera, two powerful particle spectrometers, a space-dust detector (designed and built by students at the University of Colorado) and two radio-science experiments. The entire spacecraft, drawing electricity from a single radioisotope thermoelectric generator, operates on less power than a pair of 100-watt light bulbs.

Distant observations of the Pluto system began Jan. 15 and will continue until late July 2015; closest approach to Pluto is July 14.

“There is a real possibility that New Horizons will discover new moons and rings as well,” says Alan Stern, principal investigator of the New Horizons mission. Already, Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra. Numerical simulations show that meteoroids striking those satellites could send debris into orbit, forming a ring system that waxes and wanes over time in response to changes in bombardment. “We’re flying into the unknown,” says Stern, “and there is no telling what we might find. The encounter begins next January,” adds Stern. “We’re less than a year away.”

Other than a few indistinct markings seen from afar by Hubble, Pluto’s landscape is totally unexplored. Although some astronomers call Pluto a “dwarf” planet, Stern says there’s nothing small about it. “If you drove a car around the equator of Pluto, the odometer would rack up almost 5,000 miles—as far as from Manhattan to Moscow.” Such a traveler might encounter icy geysers, craters, clouds, mountain ranges, rilles and valleys, alongside alien landforms no one has ever imagined.

The closest approach is scheduled for July 2015 when New Horizons flies only 10,000 km from Pluto, but the spacecraft will be busy long before that date. The first step, in January 2015, is an intensive campaign of photography by the Long Range Reconnaissance Imager or “LORRI.” This will help mission controllers pinpoint Pluto's location, which is uncertain by a few thousand kilometers.

"LORRI will photograph the planet against known background star fields," explains Stern. "We’ll use the images to refine Pluto’s distance from the spacecraft, and then fire the engines to make any necessary corrections.”

By late April 2015, the approaching spacecraft will be taking pictures of Pluto that surpass the best images from Hubble. By closest approach in July 2015, a whole new world will open up to the spacecraft’s cameras. If New Horizons flew over Earth at the same altitude, it could see individual buildings and their shapes. The image above NASA space-artist Ron Miller's concept of geysers and sundogs on Pluto.

He likens New Horizons to Mariner 4, which flew past Mars in July 1965. At the time, many people on Earth, even some scientists, thought the Red Planet was a relatively gentle world, with water and vegetation friendly to life. Instead, Mariner 4 revealed a desiccated wasteland of haunting beauty. New Horizons’ flyby of Pluto will occur almost exactly 50 years after Mariner 4’s flyby of Mars—and it could shock observers just as much.

Although temperatures on Pluto's surface hover around -230 °C, but researchers have long wondered whether the dwarf planet might boast enough internal heat to sustain a liquid ocean under its icy exterior.

Guillaume Robuchon and Francis Nimmo at the University of California, Santa Cruz, have calculated that the presence of an ocean depends on two things: the amount of radioactive potassium in Pluto's rocky core, and the temperature of the ice that covers it.

Density measurements suggest a rocky core fills 40 per cent of the dwarf planet's volume. If the core contains potassium at a concentration of 75 parts per billion, its decay could produce enough heat to melt some of the overlying ice, which is made of a mixture of nitrogen and water.

It should have at least that much potassium and probably more, says William McKinnon at Washington University in St Louis, Missouri, who points out that Earth, which probably formed with less of the volatile element due to its closer distance to the sun, has 10 times that concentration in its core.

Heat from Pluto's core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting. If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team concluded.

The viscosity of the ice depends on the size of individual ice particles, with smaller grains flowing more easily. There is no way to measure this from Earth, but Pluto's shape could reveal evidence of an ocean, the team says. Pluto's spin is slowing down due to tugs from its large moon Charon. Fast-spinning objects bulge out at their equator, but a soft interior would allow the world to relax into more of a sphere as its spin slows down. NASA's New Horizons probe will image the dwarf planet's shape when it flies past in 2015.

"It's very exciting to think that the dwarf planets could have astrobiological potential," says Stern. In 2011, the highly sensitive Cosmic Origins Spectrograph aboard the Hubble Space Telescope discovered a strong ultraviolet-wavelength absorber on Pluto's surface, providing new evidence that points to the possibility of complex hydrocarbon and/or nitrile molecules lying on the surface, according to researchers from Southwest Research Institute and Nebraska Wesleyan University. These chemical species can be produced by the interaction of sunlight or cosmic rays with Pluto's known surface ices, including methane, carbon monoxide and nitrogen.

"This is an exciting finding because complex Plutonian hydrocarbons and other molecules that could be responsible for the ultraviolet spectral features we found with Hubble may, among other things, be responsible for giving Pluto its ruddy color," said Stern.

The team also discovered evidence of changes in Pluto's ultraviolet spectrum compared to Hubble measurements from the 1990s. The changes may be related to differing terrains seen now versus in the 1990s, or to other effects, such as changes in the surface related to a steep increase in the pressure of Pluto's atmosphere during that same time span.

Heat from Pluto's core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting. If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team concluded.

The Daily Galaxy via Mark Showwalter/SETI, NASA/Goddard Space Flight Center and Harvard-Smithsonian Center for Astrophysics (CfA)

 

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