Pluto's outermost stellar companion, Hydra, is coated in nearly pure water ice, a new analysis found. The recent finding was derived from the new and first compositional data taken by NASA's New Horizons spacecraft on Pluto's moons.
The new data, which was taken on July 14, 2015 from roughly 150,000 miles away, was procured by the Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument onboard the spacecraft.
Collectively known as the "infrared spectra," the findings revealed that Hydra's water ice spectral signature is much stronger than the one observed in Pluto's much bigger companion, Charon. This suggested that Hydra has a darker and less dusty material as well as bigger ice particles.
"Perhaps micrometeorite impacts continually refresh the surface of Hydra by blasting off contaminants. This process would have been ineffective on the much larger Charon, whose much stronger gravity retains any debris created by these impacts," said New Horizons team member Simon Porter from the Southwest Research Institute (SwRI).
Hydra, which often appears bright and clean, has a width of approximately 31 miles. First discovered in 2005, scientists first hypothesized that it formed when Pluto and Charon collided.
Experts speculated that Hydra is roughly 4 billion years old. Because of its highly reflective surface, scientists previously hinted that it was made of water.
The team is hoping to find similar findings on Pluto's other moons, so they can compare its spectra on Charon and Hydra's confirmed data.
The mysteries of Pluto continue to baffle the scientific community. Moreover, the debate about its planetary status has kept its drive since the 2006 decision by the International Astronomical Union, which downgraded Pluto to the status of a dwarf planet.
Another recent finding about its interaction with solar winds also added to the confusion. In a study published in the Journal of Geophysical Research, researchers found that Pluto is capable of interacting with solar winds in a manner similar to our solar system's much larger stellar bodies.
This suggested that Pluto, despite its demotion as a dwarf planet, is acting more like a planet than first believed. In particular, Pluto's solar wind interaction is a cross between cometary and planetary.