Does Pluto have a tail?
Sen鈥擭ASA鈥檚 New Horizons team revealed fresh findings about Pluto today including a close-up of a vast 鈥渃racked鈥� and icy plain and the existence of a tail caused by the escaping atmosphere.
Opening a press conference, Jim Green, director of Planetary Science at NASA Headquarters in Washington, said: 鈥淲hat a historic week!鈥� And the mission鈥檚 principal investigator Alan Stern said: We鈥檝e just had the most fun. Pluto鈥檚 becoming a brand. It sells itself. You don鈥檛 really have to work that hard!鈥� He added: 鈥淚鈥檓 a little biased, but I think the Solar System saved the best for last!鈥�
First image shown was a heavily pixellated picture of one of Pluto鈥檚 tiny moons, Nix. Stern, from the Southwest Research Institute (SwRI), Boulder, Colorado, said that despite the low resolution, it showed in twice as many pixels as the best Earth-based image of Puto, which was taken with the Hubble Space Telescope.
Another image showed how early measurements have revealed an excess of the gas carbon monoxide over the bright, heart-shaped region. Stern said that no other concentration of the gas anything like that had been detected elsewhere on Pluto.
The bright zone has already been informally labelled Tombaugh Regio, in honour of Clyde Tombaugh who discovered Pluto in 1930. Within it, and north of Pluto鈥檚 icy mountains, lies a vast plain, devoid of craters, and about 20km (12 miles) wide. Its irregular, polygonal pattern resembles cracks, but the team does not yet know how they formed.
Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA鈥檚 Ames Research Center, California, told the briefing: The landscape is just astoundingly amazing. Some regions have no craters at all, so obviously younger. It shows that geological processes are happening up to the present time.鈥�
He said that the 鈥渃racked鈥� region was smooth but had irregularly-shaped segments, troughs, dark material within troughs, pitted surfaces and hills rising above the terrain. The polygons were like you might see on a boiling pot of oatmeal, or in dried mud. Another intriguing feature was a line of smudges, that might be streaks caused by prevailing winds. He said that they might point to active plumes on Pluto, though he cautioned that none had been discovered yet in the early stages of analysis.
The area has been informally dubbed Sputnik Planum, after the Russian satellite that was mankind鈥檚 first space explorer, it was announced. Another mountainous zone has been called Norgay Montes, in honour of Sherpa Tenzing Norgay who, with Edmund Hillary, became the first men to reach the summit of Mount Everest in 1952. He is the first Nepalese person to have a feature named for him anywhere in the Solar System.
The New Horizons Atmospheres team has observed Pluto鈥檚 nitrogen-rich atmosphere far beyond its surface. Fran Bagenal, of the University of Colorado, Boulder, estimated that 500 tons of material an hour was escaping from Pluto, compared to just one ton an hour on Mars which has a stronger gravitational pull, and was then being stripped away by the pressure from sunlight. It showed that a substantial amount of Pluto鈥檚 mountain ice was being removed.
Bagenal said: 鈥淲hat we think is happening is that the solar wind will eventually interact with this escaping atmosphere and may produce a shock upstream.鈥� She said that the gas was ionised as it escaped and was producing a 鈥渢ail鈥� of cold, dense tail stretching as far as 1,600 km (1,000 miles) from the dwarf planet.
A surprise guest at the conference at Johns Hopkins University Applied Physics Laboratory, Maryland, and a mission collaborator, according to Stern, was Dr Brian May, guitarist with Queen. He said: 鈥淚t鈥檚 a thrill to be with you guys. What an amazing achievement. You鈥檝e inspired the world.鈥�
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