New Horizons
Nasa's New Horizon probe is the first spacecraft to approach dwarf planet, with the expected flyby on 14 July promising to reveal mysteries of the distant frozen world Nasa

Less than 10 days away from its close encounter with the dwarf planet Pluto, Nasa's New Horizons encountered, a glitch on 4 July and the probe was switched to safe mode following the anomaly.

The probe's autopilot switched to the backup computer, which then began transmitting telemetry to Earth to help engineers troubleshoot the problem.

The probe was confirmed to be healthy and the anomaly team is working on returning New Horizons to its original flight plan.

However, given the distance, radio signals take nine hours for a round trip and it could take up to several days to resume operations, according to the mission's operations center at the Johns Hopkins University Applied Physics Laboratory.

"The mission operations center at the Johns Hopkins University Applied Physics Laboratory lost contact with the unmanned spacecraft -- now 10 days from arrival at Pluto -- at 1:54 p.m. EDT, and regained communications with New Horizons at 3:15 p.m. EDT, through NASA's Deep Space Network," the space agency reported Saturday evening.

New Horizons is 4.9 billion kilometers from Earth. The Pluto flyby is set for around 11.50am GMT on 14 July.

After a nine-year journey that began in January 2006, New Horizons is expected to pass within 10,000 km of Pluto on that day.

Pluto has at least five moons and is a binary planet system, with Pluto and Charon, both large enough to be classified as planets moving around a point in space that is in between them.

It has been unexplored by previous space missions like the Voyagers and Pioneers.

New Horizons' Long-Range Reconnaissance Imager (LORRI) camera has been clicking images of Pluto for some weeks now, but the close approach is expected to throw more light on the dwarf planet.

The probe will also study in detail the geology and chemistry of Pluto and its moons and reveal any rings circling Pluto; ice-volcanoes and unexpected interactions between Pluto and Charon.

Among the mysteries New Horizons will probe is a subsurface ocean kept warm by radioactive decay of potassium in the solar system. By looking for cracks and bulges around the equator of Pluto indicating the state of the ocean, New Horizons will help provide information.

The craft will also help estimate the mass of Pluto and its moons.

From Pluto, the probe will proceed to the Kuiper Belt, where no spacecraft has ever been before.