Heavy fighting between DR Congo's army and rebels erupted at 3.30am today around the Gorilla Sector in Virunga National Park, according to Emmanuel de Merode, Director of Virunga National Park for the Congolese Wildlife Authority.

Mortar and grenade fire have been exchanged non-stop all day between the army and the rebels, the reverberrations of which can be heard in the park and the Gorilla Sector. De Merode said at present there was no intention to evacuate the Rangers but that if the situation worsened they would leave the park station that is in close proximity to the fighting.

"This latest escalation of the conflict undermines our efforts to resume our work in the Gorilla Sector. It is almost 1 year to the day since this conflict started, but we are as determined as ever to get back in. It is critical that we know the status of the mountain gorillas," said de Merode.

Fighting between rebels, loyal to dissident General Laurent Nkunda, and the army has been ongoing in this area for 1 year , but the situation had calmed in recent months following January peace talks between armed groups in eastern DRC. Rangers however have been unable to patrol the Gorilla Sector for 12 months.

This sector - known as the Mikeno Sector - was attacked repeatedly in 2007 during which 10 mountain gorillas were killed. It was attacked in January 2007, when two Silverbacks were killed. An adult female was executed in June 2007 and in July 2007, 5 were massacred causing an international outcry. In September a dead infant female was found in the hands of alleged traffickers.

Some 1,100 Wildlife Rangers protect the National Parks of Eastern Congo, a region affected by a 10-year civil war and current political instability. These parks are home to mountain gorillas, chimpanzees, forest elephants and rhinos. The Rangers have remained active in protecting these parks, four of which have been classified as World Heritage Sites by UNESCO.

Mountain Gorillas are critically endangered, with only 700 remaining in the world, about 380 in the Virunga Volcanoes Conservation Area (shared by DRC, Rwanda and Uganda ) and 320 in the Bwindi Impenetrable Forest, Uganda. Despite the conflict in the region, their decline had been reversed up until January 2007 thanks to international support and courageous conservationists coupled with the popularity of gorilla-watching tourism. At September 2007 there were 72 habituated Mountain Gorillas in DR Congo.

The Congolese Wildlife Authority (ICCN) and its Rangers work throughout the country to protect the National Parks of Congo and their wildlife from poachers, rebel groups, illegal miners and land invasions. Over 150 Rangers have been killed in the last 10 years protecting the 5 parks of eastern DRC, and Rangers worked throughout the civil war without receiving a salary.

Virunga National Park, Africa ’s oldest national park (established in 1925) and a UNESCO World Heritage Site since 1979, is home to 200 of the world’s mountain gorillas. Formerly known as Albert National Park, Virunga lies in eastern DR Congo and covers 7,800 square kilometers.

Oxygen is constantly leaking out of Earth’s atmosphere and into space. Now, ESA’s formation-flying quartet of satellites, Cluster, has discovered the physical mechanism that is driving the escape. It turns out that the Earth’s own magnetic field is accelerating the oxygen away.

The new work uses data collected by Cluster from 2001 to 2003. During this time, Cluster amassed information about beams of electrically charged oxygen atoms, known as ions, flowing outwards from the polar regions into space. Cluster also measured the strength and direction of the Earth’s magnetic field whenever the beams were present.

Hans Nilsson, Swedish Institute of Space Physics, headed a team of space scientists who analysed the data. They discovered that the oxygen ions were being accelerated by changes in the direction of the magnetic field. “It is a bit like a sling-shot effect,” says Nilsson.

Having all four Cluster spacecraft was essential to the analysis because it gave astronomers a way to measure the strength and direction of the magnetic field over a wide area. “Cluster allowed us to measure the gradient of the magnetic field and see how it was changing direction with time,” says Nilsson.

Before the space age, scientists believed that Earth’s magnetic field was filled only with particles from the solar wind, the constant sleet of particles that escapes from the Sun. They thought this formed a large cushion that protected the Earth’s atmosphere from direct interaction with the solar wind.

“We are beginning to realise just how many interactions can take place between the solar wind and the atmosphere,” says Nilsson. Energetic particles from the solar wind can be channelled along the magnetic field lines and, when these impact the atmosphere of the Earth, they can produce aurorae. This occurs over the poles of Earth. The same interactions provide the oxygen ions with enough energy to accelerate out of the atmosphere and reach the Earth’s magnetic environment.

The Cluster data were captured over the poles with the satellites flying at an altitude of anywhere between 30,000 and 64,000 kilometres. Measurements taken by earlier satellites during the 1980s and 1990s showed that the escaping ions were travelling faster the higher they were observed. This implied that some sort of acceleration mechanism was involved and several possibilities were proposed. Thanks to this new Cluster study, the mechanism accounting for most of the acceleration has now been identified.

At present, the escape of oxygen is nothing to worry about. Compared to the Earth’s stock of the life-supporting gas, the amount escaping is negligible. However, in the far future when the Sun begins to heat up in old age, the balance might change and the oxygen escape may become significant. “We can only predict these future changes if we understand the mechanisms involved,” says Nilsson.

For now, Cluster will continue collecting data and providing new insights into the complex magnetic environment surrounding our planet.