New Horizons Now Sees Pluto’s Moons Kerberos and Styx

May 18, 2015

As New Horizons space probe approaches Pluto, it has finally spotted two of the planet’s most recently discovered moons, Kerberos and Styx.

New Horizons' LORRI instrument took this photo of Pluto and all of its moons. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

New Horizons space probe launched in 2006 and is now only 88 million kilometres from Pluto and its moons. As it approaches the system, it is able to spot more and more details with its Long Range Reconnaissance Imager (LORRI).

This is important because after the New Horizons mission was done planning and launched, four new Pluto’s moons have been discovered. Not only are we unable to determine the exact size of some of them, because they are too small and too distant, but this presents a potential danger for New Horizons probe.

Recently, New Horizons has possibly spotted ice caps on Pluto’s poles. Now, as it approaches the dwarf planet, it could potentially discover previously unseen moons or even planetary rings.

Kerberos and Styx were discovered in 2011 and 2012, respectively. The former has diameter of only 14 to 44 kilometres and the latter is 8 to 28 kilometres wide. These are the most accurate values we can observe from Earth at the moment, but as New Horizons’ July 14 flyby of the system approaches, better observations are expected. From May 15 until two months after the flyby, New Horizons’ LORRI camera will be able to take better images than Hubble Space Telescope.

“New Horizons is now on the threshold of discovery,” said mission member John Spencer, of the Southwest Research Institute in Boulder, USA. “If the spacecraft observes any additional moons as we get closer to Pluto, they will be worlds that no one has seen before.”

As Pluto’s tiny moons Kerberos, Styx and before them in 2005 Nix and Hydra, have been discovered, the possibility of even smaller objects and moons in the dwarf planet’s orbit increased. This would imply that a Kuiper Belt Object collided with Pluto in the past, ejecting debris into its orbit. Charon, the largest moon of Pluto, was then created from this debris, but if there are other, significantly smaller moons, the whole system around the dwarf planet could be more complex than we thought just 10 years ago.

We are awaiting with excitement what New Horizons will find, since its flyby of Pluto is less than two months away and in the meantime, we can await more photos from its LORRI camera.

“Detecting these tiny moons from a distance of more than 88 million kilometres is amazing, and a credit to the team that built our LORRI long-range camera and John Spencer’s team of moon and ring hunters,” said Alan Stern, also of the Southwest Research Institute, who is principal investigator of the New Horizons mission.




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