Seeker Archives

Ammonia 'Splat' on Charon Could be a Fresh Impact

Scientists analyzing the spectacular high-resolution data streaming back from NASA's New Horizons mission have discovered something curious about a crater on Pluto's largest moon, Charon.

Scientists analyzing the spectacular high-resolution data streaming back from NASA's New Horizons mission have discovered something curious about a crater on Pluto's largest moon, Charon.

NEWS: ‘Star Wars' and ‘Star Trek' Collide on Pluto Moon Charon

In the false color image of the crater above (sadly, the crater isn't really a vivid green), high concentrations of ammonia seem to accumulate in and around the Pluto-facing crater informally named Organa. The ammonia ice-filled crater appears to be unique in the observations of Charon's surface so far - the ice dramatically contrasts with the spectroscopic composition of the surrounding landscape.

The similarly-sized Skywalker crater seen just below Organa does not contain a strong ammonia ice signal and instead contains water ice, which is common on Charon.

NEWS: Pluto has Ice Mountains, Charon is Active

"Why are these two similar-looking and similar-sized craters, so near to each other, so compositionally distinct? We have various ideas when it comes to the ammonia in Organa. The crater could be younger, or perhaps the impact that created it hit a pocket of ammonia-rich subsurface ice. Alternatively, maybe Organa's impactor delivered its own ammonia," said Will Grundy, New Horizons Composition team lead from Lowell Observatory in Flagstaff, Ariz.

The ammonia-covered crater, which almost looks like a giant paintball splat, is approximately 3 miles wide - around the same size as Skywalker. But their dramatic compositional differences could reveal some fascinating science about Charon's geology.

ANALYSIS: New Horizons Reveals a Psychedelic Pluto and Charon

"This is a fantastic discovery," said Bill McKinnon, deputy lead for the New Horizons Geology, Geophysics and Imaging team from Washington University in St. Louis. "Concentrated ammonia is a powerful antifreeze on icy worlds, and if the ammonia really is from Charon's interior, it could help explain the formation of Charon's surface by cryovolcanism, via the eruption of cold, ammonia-water magmas."

In the Kuiper belt, over 40 times further away from the sun than Earth, icy volatiles reign supreme. Chemicals like ammonia have lower freezing points than other substances like water, and so the presence of quantities of ammonia could indicate active flows of icy materials from inside Charon. But did this ammonia really come from inside the moon? For now, planetary scientists aren't sure, but as more data is sent from New Horizons as it races deeper into the Kuiper belt, a better picture should form as to where Charon got its ammonia.

Source: NASA

The informally named Organa crater (shown in green) is rich in frozen ammonia and -- so far -- appears to be unique on Pluto’s largest moon.

After several false starts, NASA in 2001 agreed to fund an independent effort to fly a spacecraft to Pluto, the only member of the solar system’s original nine planets that hadn’t been explored. Five years later, New Horizons blasted off to begin a nearly 3 billion mile journey to Pluto, farther than any probe has traveled since the 1970s-era Pioneer and Voyager spacecraft.

Here’s a look at the New Horizons mission by the numbers.

MORE: From the Start, Pluto was a Puzzle: Timeline

Launching a small spacecraft on a big rocket is one way to get going fast. Slingshotting off giant Jupiter’s gravity is another. New Horizons did both, and still the journey to distant Pluto took nearly 10 years. It is zipping along at about 31,000 mph -- fast enough to fly from New York City to Los Angeles in less than 5 minutes.

MORE: Fuzzy to Clear: Space Robots Snap Solar System Into Focus

Image: Viewed from the top of the Vehicle Assembly Building at Kennedy Space Center, NASA’s New Horizons spacecraft roars off the launch pad aboard an Atlas V rocket on Jan. 19, 2006.

At its closest approach, New Horizons will pass about 7,750 miles from Pluto and about 17,900 miles from its orbital mate Charon. The view will be about 500 times better than this image, taken on July 7 when New Horizons was just less than 5 million miles from Pluto. New Horizons will pass through the Pluto system in about 30 minutes. The probe carries seven science instruments, including LORRI, the Long Range Reconnaissance Imager, telescope.

MORE: Once Just a Speck of Light, Pluto About to Be Unveiled

During the encounter, New Horizons will take hundreds of pictures in both visible and near-infrared wavelengths. The best images should depict surface features as small as 200 feet across. With nearly 3 billion miles between New Horizons and Earth, a radio signal, which travels at the speed of light, will take about 4.5 hours to reach Earth.

MORE: New Horizons is Carrying 9 Stowaways to Pluto

Image: An artist's impression of Pluto's surface reveals an icy surface -- we're about to find out what Pluto is really made of.

With just one shot to get a close-up view of Pluto, New Horizons is designed to gather as much data as possible, as quickly as possible. In all, scientists expect the spacecraft to collect 100 times more data during closest approach than it can transmit back to Earth just after the encounter. A few high-priority images and data will be sent back just before and after closest approach, but the rest will trickle in over the next 16 months.

MORE: Pluto Flyby Begins: NASA Probe Enters Encounter Phase

Image: Diagram showing the sequence of events during New Horizons' encounter with the Pluto system.

New Horizons draws electricity from a single radioisotope thermoelectric generator, or RTG, which converts heat given off by the natural decay of about 24 pounds of radioactive plutonium. It runs on less power than a pair of 110-watt light bulbs.

MORE: Student Experiment Will Count Cosmic Particles Around Pluto

Image: Artist's impression of New Horizons flying past Jupiter, with its RTG visible in the lower right of the image.

After its Pluto flyby, New Horizons will continue out into the Kuiper Belt region of the solar system. Scientists hope to extend its mission so it can pass by at least one of the thousands of icy bodies that orbit in this vast domain. Eventually, New Horizons will end up leaving the solar system. It is expected to remain viable until the late 2030s.

MORE: After Pluto, Where Will NASA's New Horizons Go?

Image: Artist's impression of New Horizons encountering a Kuiper Belt object beyond Pluto.