New Horizons Captures Images of Pluto's Smaller Moons Nix and Hydra

Posted on July 23, 2015

NASA's New Horizons team has shared an image of Pluto's smaller moons Nix (left) and Hydra (right). The images were taken on the morning of July 14, 2015 and received on the ground on July 18.

New Horizons was about 165,000 km (102,000) miles away from Nix when the Nix image was taken with the New Horizons Ralph instrument. It was 143,000 miles (231,000 kilometers) from Hydra when the black and white image was taken from New Horizons' LORRI instrument.

Nix is estimated to be 26 miles (42 kilometers) long and 22 miles (36 kilometers) wide. It is shaped like a jelly bean. The reddish region pictured on the image is expected to be a crater.

Mission scientist Carly Howett, Southwest Research Institute, Boulder, says in a statement, "Additional compositional data has already been taken of Nix, but is not yet downlinked. It will tell us why this region is redder than its surroundings. This observation is so tantalizing, I'm finding it hard to be patient for more Nix data to be downlinked."

Scientists estimate Hydra to be about 34 miles (55 kilometers) long and 25 miles (40 kilometers) wide. The new image shows two large craters on Hydra. The upper right portion of Hydra looks darker than the rest. The astronomers say this suggests a possible difference in surface composition.

Mission science collaborator Ted Stryk of Roane State Community College in Tennessee says in a statement, "Before last week, Hydra was just a faint point of light, so it's a surreal experience to see it become an actual place, as we see its shape and spot recognizable features on its surface for the first time."

A larger version of the above image can be found here. NASA astronomers are expecting New Horizons to transmit data of Pluto's most recently discovered moons Styx and Kerberos to Earth no later than mid-October.

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