Shuttle flaw shows again

Nasa's space shuttle Atlantis is believed to be fitted with flawed engine seals that should have been thrown away.

The discovery is embarrassing for the US space agency as it is the second time in a few months that defective seals have turned up.

Two seals intended for the scrap heap are apparently in one of Atlantis' main engines, chief engineer Len Worlund said on Wednesday.

As a result, Nasa will replace that engine before the shuttle blasts off next month with supplies for the international space station.

Mr Worlund said the flawed seals are probably safe to fly, but as a precaution will be removed along with the rest of the engine. It is not clear if the work will delay Atlantis' launch, expected around 17 April.

The problem with the seals arose in late January, when Nasa discovered that a rejected seal ended up in an engine that helped propel Discovery to orbit in December.

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Fuel cell breakthrough

The prospect of clean, green car engines appears closer with a breakthrough in fuel cell technology by US scientists.

A team from the University of Pennsylvania has created a fuel cell which runs on natural gas and the researchers are hopeful they can develop versions which run on normal petrol or diesel fuel.

Fuel cells have long excited scientists and environmentalists because they convert fuel into electricity very efficiently and produce only water as a waste product, rather than carbon dioxide and other pollutants.

The barrier to their wider use is that up till now the only suitable fuel was hydrogen. This pure gas is not only difficult to handle but also requires lots of energy to produce in the first place.

But if more common fuels, like petrol, are used the cells rapidly choke up with carbon. This is the problem the US team has overcome.

The cell has been successfully tested on a range of gases, including methane, ethane and butane. The power output is still low - just 10% of a conventional hydrogen fuel cell - but this can be improved, the scientists say in the journal Nature.

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End of Iridium postponed

Debt-ridden company Iridium has been given a last-gasp lease of life by a New York bankruptcy court.

With just hours to go before the start of an enforced shutdown on Wednesday, the court extended the deadline for the satellite-based mobile phone company to find a new backer.

The next hearing is scheduled for 27 March, when the company's request for a further 45-day extension will be considered.

The extension was requested with the consent of Iridium's creditors and came less than two weeks after wireless magnate Craig McCaw abandoned plans to invest in the debt-plagued company. Mr McCaw is now backing a rival troubled company, ICO Communications.

Iridium has signed up only 50,000 subscribers since launching its service in the autumn of 1998 and has debts of about $4.4 billion. If the company is wound up, its 66 satellites are likely to be taken out of orbit and left to burn up in the Earth's atmosphere.