New Horizons to study spider-like patterns on Pluto

Chuck Bednar for – @BednarChuck

When NASA’s New Horizons spacecraft makes its flyby of Pluto in July, scientists are hoping to get an up-close look at dark, spider-like surface patterns caused by nitrogen ice and gas eruptions triggered during the dwarf planet’s ice geyser season.

As Discovery News explained on Friday, during Pluto’s ice geyser season, sunlight hits its north pole, causing ice and gas to spray across the surface. The patterns formed as a result of this odd phenomenon have been spotted several times over the years by ground-based observatories, and by the Hubble Space Telescope, but the US space agency is hoping to get a closer look.

Past observations have been unable to resolve details of the dwarf-planet’s surface, but have managed to confirm color and lighting changes that have taken place on a grand scale over the past four years. New Horizons could shed new light on these changes.

Evidence of frost movement found on the dwarf planet

Bonnie Buratti of NASA’s Jet Propulsion Laboratory told the website that she and her colleagues are “pretty certain there is some kind of movement of frost” on Pluto. To support that theory, she cites evidence of telescope observations demonstrating how the planet reflects light while it spins on its axis.

Buratti and her colleagues compared those curves to simulated ones which assume that there is no frost rising from Pluto’s ice caps and being deposited elsewhere, causing some of the surface to become darker and others to become lighter, the website said. The modeled light curves do not match the observed ones, the JPL researcher explained.

“We compared it and for the last four years we’ve had substantial changes,” Buratti explained to Discovery News. Those changes are taking place as Pluto moves further away from the sun, but also during a period when the north pole of the planet is turning towards the star at the center of the solar system, creating an Earth-like northern summer.

Pluto could have geysers

Buratti and colleagues from Boston University, UCLA and Grays Harbor College report their findings on Pluto in the Astrophysical Journal Letters. They predict that New Horizons will find explosive geysers similar to those previously found on Triton and Mars, in light of the similarity between the dwarf planet and Neptune’s largest moon.

“We are pretty close to polar summer – so there is a lot of frost there to sublimate,” she pointed out, referring to the process where solid ice skips the liquid phase and turns directly into gas. As the sun’s rays hits the surface, they should be powerful enough to penetrate frozen nitrogen, even though Pluto is 32 times farther away from the sun than the Earth.

That would allow the dwarf planets polar cap to trap enough energy to convert some of that ice into pockets of gas, which accumulates pressure until it breaks through the surface. The impact of that blast would send nitrogen ice crystals all over the place, forming the spider-like patterns. Data from New Horizons should be able to prove or disprove this hypothesis.


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