Pluto's icy surface revealed

The first close-up images of Pluto released from the historic flyby of Nasa's New Horizons probe show icy mountain ranges 3500 metres high.

New close-up images reveal a range of mountains rising as high as 3500 metres, believed to be relatively young - formed a mere 100 million years ago. Photo: NASA / JHUAPL

Remarkable new details of Pluto’s largest moon Charon are revealed in this image from New Horizons’ Long Range Reconnaissance Imager (LORRI), taken from a distance of 289,000 miles (466,000 kilometers). Photo: NASA / JHUAPL

Guests and New Horizons team members countdown to the spacecraft's closest approach to Pluto, Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Photo: NASA / Bill Ingalls

The latest spectra from New Horizons Ralph instrument reveal an abundance of methane ice, but with striking differences from place to place across the frozen surface of Pluto.

New Horizons Flight Controllers celebrate after they received confirmation from the spacecraft that it had successfully completed the flyby of Pluto, Tuesday, July 14, 2015 in the Mission Operations Center (MOC) of the Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Maryland. Photo: NASA / Bill Ingalls

Pluto’s North Pole, Equator, and Central Meridian. Photo: NASA

Nasa said the pictures suggested Pluto was geologically active and quite youthful in astronomical terms - possibly less than 100 million years old.

The information New Horizons gathered as it flew by the dwarf planet is only beginning to reach Earth, after a journey of nearly 10 years and almost five billion kilometres.

The data will keep coming in over the next 16 months.

Mission scientist John Spencer told journalists that one image of Pluto's surface showed a terrain that had been resurfaced by some geological process - such as volcanism - in the last 100 million years.

"We have not found a single impact crater on this image. This means it must be a very young surface," he said.

This active geology needs some source of heat. This has only been seen on icy moons, where it can be explained by "tidal heating" caused by gravitational interactions with the host planet.

"You do not need tidal heating to power geological heating on icy bodies. That's a really important discovery we just made this morning," said Dr Spencer.

He said the methane and nitrogen ice that coated Pluto's surface were not strong enough to form mountains, so they were probably composed of Pluto's water-ice bedrock.

Today, the @NASANewHorizons team is bringing what was previously a blurred point of light into focus. pic.twitter.com/AswUMZFxqd

— NASA (@NASA) July 15, 2015

The pictures were sent back to Earth during the course of two data downlinks on Wednesday.

A new, close-up image of Charon revealed a chasm 6-10km deep and also further evidence of active resurfacing.

The mission team has told New Horizons this week to send down only a small fraction of the total data it carries. Part of the reason is that the probe continues to do science, observing Pluto from its night side.

- AFP / BBC / NASA