Satellite falls off US west coast

24 September 2011 Last updated at 16:13 GMT By Jonathan Amos Science correspondent, BBC News The BBC's Andy Moore says where debris came down is "a bit of a mystery"

Nasa says its six-tonne UARS satellite plunged to Earth over the Pacific Ocean, off the US west coast.

It appears likely the decommissioned craft came down between 03:23 and 05:09 GMT - with a best estimate of 04:16.

If correct, this means any debris that survived to the surface probably went into water and not on land.

The Upper Atmosphere Research Satellite (UARS) is the largest American space agency satellite to return uncontrolled into the atmosphere in about 30 years.

The fall to Earth was monitored by the Joint Space Operations Center (JSPOC) at Vandenberg Air Force Base in California. Its best estimate for the timing of the re-entry would have seen UARS come in at a point well out into the North Pacific.

However, if UARS re-entered many minutes after 04:16, it is possible debris could have reached the American landmass.

There were some unconfirmed reports of glowing wreckage moving across the sky in western Canada, but Nasa said it had yet to receive credible evidence that this was so, less still that any debris items had been found.

"I've got no reports that I've seen that talk about people who think they might have recovered debris," Nick Johnson, Nasa's chief scientist for orbital debris at the Johnson Space Center in Houston, told reporters during a media teleconference.

"Obviously, we're going to continue to keep our eyes and ears open, and if we receive any reports like that we'll try to go verify."

Most of the 20-year-old satellite should simply have burnt up on re-entry into the Earth's atmosphere, but modelling work indicated perhaps 500kg could have survived to the surface.

Calculations estimated this material would have been scattered over an 800km path. Nonetheless, with more than 70% of the Earth's surface covered by water, many experts had offered the view in recent weeks that an ocean grave was going to be the most probable outcome for UARS.

"Because we don't know where the re-entry point actually was, we don't know where the debris field might be. If the re-entry point was at the time that JSPOC has its best guess of 04:16 GMT then all that debris wound up in the Pacific Ocean," Nick Johnson reiterated.

UARS was deployed in 1991 from the space shuttle Discovery on a mission to study the Earth's upper atmosphere.

It contributed important new understanding on subjects such as the chemistry of the protective ozone layer and the cooling effect volcanoes can exert on the global climate.

Astrophotographer Thierry Legault's video of the falling UARS

In the past few days, Nasa had warned members of the public not to touch any pieces of the spacecraft that might survive the fall to land, urging them to contact local law enforcement authorities instead.

"I've seen some things that have re-entered and they tend to have sharp edges, so there's a little concern that they might hurt themselves if they try to pick them up," said Mark Matney, an orbital debris scientist from Nasa's Johnson Space Center.

Under the terms of the Outer Space Treaty of 1967, the US government retains ownership of the debris and could, if it so wished, seek to take possession of any items found on the ground.

With those ownership rights also comes absolute liability if a piece of UARS is found to have damage property or injured someone.

"There is something called international responsibility; they're internationally liable," explained Joanne Wheeler of law firm CMS Cameron McKenna, and an expert representative for the UK on the UN Subcommittee for the Peaceful Uses of Outer Space.

"The Americans have to retain jurisdiction and control, and that pretty much can be interpreted as ownership. So they own it up there, they own it if it comes down to Earth and they're liable if it crashes into something."

Tracking stations will typically witness the uncontrolled return of at least one piece of space debris every day; and on average, one intact defunct spacecraft or old rocket body will come back into the atmosphere every week.

Something the size of UARS is seen perhaps once a year. Much larger objects such as space station cargo ships return from orbit several times a year, but they are equipped with thrusters capable of guiding their dive into a remote part of the Southern Ocean.

UARS orbited the Earth between 57 degrees North and SouthNasa calculated some 26 components might survive the fall to EarthThe largest was a moveable instrument platform weighing almost 160kgIn total, about half a tonne could have made it all the way to the surfaceThe risk of any one of 7bn people being hit was 1 in 3,200, Nasa saysJonathan.Amos-INTERNET@bbc.co.uk

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Ivory Coast

9 August 2011 Last updated at 15:50 GMT Once hailed as a model of stability, Ivory Coast has slipped into the kind of internal strife that has plagued many African countries.

An armed rebellion in 2002 split the nation in two. Since then, peace deals have alternated with renewed violence as the country has slowly edged its way towards a political resolution of the conflict.

For more than three decades after independence under the leadership of its first president, Felix Houphouet-Boigny, Ivory Coast was conspicuous for its religious and ethnic harmony and its well-developed economy.

All this ended when the late Robert Guei led a coup which toppled Felix Houphouet-Boigny's successor, Henri Bedie, in 1999.

Mr Bedie fled, but not before planting the seeds of ethnic discord by trying to stir up xenophobia against Muslim northerners, including his main rival, Alassane Ouattara.

This theme was also adopted by Mr Guei, who had Alassane Ouattara banned from the presidential election in 2000 because of his foreign parentage, and by the only serious contender allowed to run against Mr Guei, Laurent Gbagbo.

Continue reading the main story Politics: Civil war in 2002 split country between rebel-held north and government-controlled south; 2007 power-sharing deal brought peace; 2010 presidential poll led to stalemateEconomy: Ivory Coast is world's leading cocoa producer; UN sanctions imposed in 2004 include an arms embargo and a ban on diamond exportsWhen Mr Gbagbo replaced Robert Guei after he was deposed in a popular uprising in 2000, violence replaced xenophobia. Scores of Mr Ouattara's supporters were killed after their leader called for new elections.

In September 2002 a troop mutiny escalated into a full-scale rebellion, voicing the ongoing discontent of northern Muslims who felt they were being discriminated against in Ivorian politics. Thousands were killed in the conflict.

Although most of the fighting ended in 2004, Ivory Coast remained tense and divided. French and UN peacekeepers patrolled the buffer zone which separated the north, held by rebels known as the New Forces, and the government-controlled south.

After repeated delays, elections aimed at ending the conflict were finally held in October 2010. But the vote ushered in more unrest when the incumbent, Laurent Gbagbo, refused to concede victory to the internationally recognised winner, Alassane Ouattara.

The ensuing four-month stand-off was only ended when Mr Ouattara's forces overran the south of the country, finally capturing Mr Gbagbo and declaring him deposed.

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Rights group: mass displacements in Ivory Coast (AP)

ABIDJAN, Ivory Coast – Hundreds of thousands of people are still too terrified to return home more than three months after the end of postelection violence in Ivory Coast, a human rights group reported Wednesday.

Amnesty International says in a new report that traditional hunters allied with President Alassane Ouattara continue to intimidate certain ethnic groups perceived to have supported former president Laurent Gbagbo. As a result, almost 700,000 people refuse to leave the refugee camps and remote villages where they went to flee the fighting.

The report said the group of hunters, known as the Dozos, carried out targeted killings and attacks in the months following Gbagbo's fall from power, together with rebels who are now integrated into the national army.

The rights group called for the demobilization and disarmament of all irregular fighters. Security throughout the country should be established by the national security forces to provide "conditions that will eventually support the safe and durable return of displaced persons and refugees," the report said.

Ouattara named a new army chief this month, but a half-dozen warlords who formed a coalition to bring him to power still each control sections of the country.

Gbagbo was arrested in April after six months of violence sparked by his refusal to accept defeat in a November presidential election. The United Nations and many rights groups have accused both sides of carrying out war crimes and crimes against humanity during the ensuing political standoff.

The International Criminal Court has been asked to investigate. The U.N. and the Ivorian government also have ongoing war crimes investigations. Gbagbo remains in detention without charge in the north of the country.

Earlier Wednesday, Ouattara said during a visit to the U.N. that he is unfamiliar with a specific case of politically motivated violence that occurred on the banks of the Cavallay River in western Ivory Coast on May 22, the day after his inauguration.

The Associated Press reported this week that Ouattara loyalists massacred as many as 47 people in that region, known as a stronghold of political opponent Laurent Gbagbo.

"Once we get the report we will be able to say what happened," Ouattara said, referring to his country's national inquiry.

Ouattara met earlier Wednesday with U.N. Secretary-General Ban Ki-moon, and was to meet with President Barack Obama in Washington on Friday.

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Associated Press writer Anita Snow contributed to this report from the United Nations.

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