However, the new data does not mean the Earth has shrunk. The new figure is simply more accurate, thanks to more accurate measurements, more data and better geophysical models.

The reduction makes no tangible difference to everyday life – it will not noticeably shorten your journey to work. But it is crucial in other ways, such as in the detection of sea-level rises, says Axel Nothnagel, at the University of Bonn in Germany who led one part of the project.

“It is essential for the positioning of the satellites that measure rises in sea level – they must be accurate to the millimetre,” says Nothnagel, who led the German team. “If the positions of the ground stations tracking the satellites are not accurate to the millimetre, then the satellites cannot be accurate either.”

The scientists round the number up to 12,756.274 kilometres (7,926.3812 miles) for the general use.

Global network

The new measurement was made by combining data obtained via three different techniques. The first is a method known as , which exploits the radio waves that arrive on Earth from distant astronomical sources such as quasars.

“A network of more than 70 radio telescopes worldwide receives these waves, but because the stations are so far apart from each other, the signals are received at slightly different times,” explains Nothnagel, who led the . “From this difference we can measure the distance between the radio telescopes with an accuracy of 2 mm in 1000 kilometres.”

The second method is called satellite laser ranging, which uses lasers to measure the distances between the Earth and orbiting satellites. The final method makes precise measurements between the Earth and GPS and DORIS satellites.

The synthesis of all the data collected up to 2005 took two years. It was organised by the , who combined the data into a single common

framework, called the .

The most powerful camera ever sent to Mars has developed a worrying glitch, along with a second instrument aboard NASA’s Mars Reconnaissance Orbiter.

The problems come in the month in which the spacecraft is set to surpass the record for the most science data returned by any craft sent to the Red Planet.

In late November 2006, the team operating the High Resolution Imaging Science Experiment camera noticed a significant increase in noise in one of its 14 camera detector pairs. Another detector that developed the same problem soon after launch has worsened.

Then, images sent from the spacecraft camera in January revealed the first signs of this problem in five other detectors. Mission managers say that while the current impact on image quality is small, there is concern that the problem could continue to worsen.

Lakes and lost rovers

Tests have shown that increasing the warming of the camera’s electronics before an image is taken reduces or eliminates the problem. Engineers will use this clue to try to understand the cause of the difficulty and either work out a way to fix it, or work around it.

The camera continues to make observations. As recently as 1 February, it sent back dramatic new images of Martian gullies.

Previously, its sharp vision spotted several spacecraft sitting on the Red Planet’s surface (see Mars probe may have spotted lost rover). It also spotted a stunning patch of frozen water ice lying inside a crater.

Climate scanner

The second MRO instrument causing concern is the Mars Climate Sounder, which scans the atmosphere. It maps the temperature, ice clouds and dust distributions seen on each of nearly 13 orbits every day. But in late December anomalies were seen in the movement of the sounder, leaving its field of view slightly out of position.

The mission team sent new data tables that govern how the instrument scans, and the position errors stopped. However, in mid-January, the position errors reappeared. Although still intermittent, the errors became more frequent, so the instrument has been turned off while the science team investigates the problem.

Since beginning its primary science phase in November 2006, MRO has returned 6 terabits of data, enough to fill nearly 1000 CD-ROMs. This equals the record for Mars data set between 1997 and 2006 by NASA’s Mars Global Surveyor mission.

The rate of data return is expected to increase over the coming months as the relative motions of Earth and Mars in their orbits around the Sun cuts the distance between the planets.

By the conclusion of its first science phase, in 2008, the mission is expected to have returned more than 30 terabits of science data. Besides enriching our understanding of Mars, the observations will also be used to evaluate potential landing sites for future missions.

And each year, the politicians find themselves snagged between the demands of scientists to protect stocks – particularly cod – and those of fishermen to protect their livelihoods. (See, for example, our stories on the meeting from 2004 and 2003.)

The 2006 meeting proved no different, reaching a middle-ground compromise that pleased neither camp. The EU Fisheries Minister Joe Borg said: “The result was a proposal that has been severely criticised by all sides for being too drastic for some and too weak for others.” He argues the new quotas represent a “gradual but sustained approach to delivering sustainable fisheries”.

But Tom Pickerell, at wildlife campaign group WWF, said: “The scientists must wonder why they bother with their surveys. It amazes me that world-class survey results are treated with such disdain, while anecdotal views from [fishermen] with vested interests in maintaining quotas are often given credence. We will now need a miracle to save cod.”

David Read, Vice President of the Royal Society – the UK national academy of science – added: “Yet again we have seen scientific advice on cod quotas being compromised by political decisions. Given the already alarming condition of stocks, European Fisheries Ministers should be clear that they may be presiding over the total collapse of cod in the Atlantic. And if this does happen, we can’t be sure that there is any possibility of recovery.”

A major study, published in the journal Science in November 2006 predicted that all commercial fisheries may die out by 2050.

No ban plans

Before the meeting, EU’s scientific advisers – the International Committee for the Exploration of the Sea – called for a complete ban on cod fishing in Europe, as they have since at least 2002 (see Cod fishing ban needed in Europe). The European Commission then proposed a 25% cut.

In the end, ministers agreed a 20% cut in waters to the west of the UK, 14% in the North Sea and 15% elsewhere. The number of days allowed for cod fishing was also reduced by between 7% and 10% depending on the mesh size of the net used.

Borg said there were indications that more juvenile cod are present than in 2006: “This is the first indication that there is a recovery in cod,” he said. WWF say the key issue of cod bycatch has not been dealt with – these are cod caught in nets trawling for other species and often thrown back dead.

For other fisheries, the following quota changes were agreed:

• increases in quotas for prawns, haddock, mackerel and monkfish

• 12% increase in Bay of Biscay sole

• 20% increase in northern hake

• limited lifting of ban on anchovy fishing

• 12% decrease in plaice

• 10% decrease in tuna in the Mediterranean

The communist state had signalled the underground test was to take place. It carried out its threat on Monday, despite warnings from the international community. A statement by the nation’s official news agency said: “It has been confirmed that there was no danger such as radioactive emission in the course of the nuclear test.”

North Korea says it performed the test to deter a military attack from the US. “It marks a historic event as it greatly pleased the Korean People’s Army and people that wished to have a powerful self-reliant defence capability.”

Officials in South Korea said an explosion had been detected in the north of its neighbour’s territory, which measured 3.5 on the Richter scale. The US Geological Survey also detected the explosion, giving its magnitude as 4.2, equivalent to a “light” earthquake.

The USGS pinpointed the location as 41.311°N, 129.114°E – 385 km (240 miles) north-east of Pyongyang. The time of the explosion is given as 1035 local time (0135 GMT).

Unwieldy device

However, the bomb detonated by North Korea is not “weapons deliverable”, according to Joseph Cirincione at the Center for American Progress, a Washington DC-based think tank. “It can’t be put on a missile and is probably too big for a plane,” Cirincione told the BBC.

The international reaction to the test has been both swift and highly critical. The US called it a “provocative act” that would aggravate tensions in northeast Asia and called for the UN Security Council to take immediate action.

China called the test brazen, while Japan labelled it unpardonable. South Korea stated that its neighbour’s behaviour was a “grave threat to peace and stability”.

North Korea resumed missile testing in July 2006, after eight launch-free years. The country test-fired seven missiles over the Sea of Japan (see North Korea resumes missile testing).

After over 100 years together, our love affair with the motor car shows no sign of fading. Almost 40 million cars were produced in 35 countries in 2001 alone. In fact, for some people cars have come to take on almost human characteristics.

But cars, trucks and motorbikes have come a long way since first chugging along at walking speeds, and following the creation of the first modern-style cars in the mid 1880s, much of the early development focused on making them faster and cheaper. The need for speed continues today, but mainly in the multi-million dollar world of racing cars, where some teams are even trying to breed speed.

Engineering safety

However, with 1.2 million road deaths worldwide each year, plus a further 50 million injuries, and with climate change causing global concern, much research now is focused on safety and new fuels – though even some electric vehicle and biofuel research aims at going faster.

Travelling at speed has always been risky, as the wavers of the red flag who preceded the first cars signified. One cutting edge area of research in motoring safety is the use of digital in-car assistants that can ensure you don’t miss crucial road signs or fall asleep.

The use of artificial intelligence software allows these assistants to monitor your driving and makes sure your phone or radio doesn’t distract you at a vital moment, and can even identify your emotions to help with safer driving.

Most crashes result from human and not mechanical faults and much research is being done on behavioural aspects of driving, including the influence of fast music and obesity.

Some safety developments aim to improve your vision. Radar can spot obstacles in fog or guide you in tricky parking manoeuvres, while other technology “sees through” high-sided vehicles blocking your view.

And refinements to seat belts, pedal controls and tyres are making driving smoother and safer. In the event of a prang, smart headrests and crumpling bonnets (or hoods) are helping protect both drivers and pedestrians.

The colour of a car has been found to be linked with safety, as has, less surprisingly, size and shape, with SUVs being frequently criticised.

Future fuels

SUVs are also criticised by some for their high fuel consumption, and alternatives to fossil-fuel-based gasoline, such as plant oils or hybrid engines, are a hot area of research. Brazil already makes widespread use of ethanol derived from sugar cane. Fuel cells based on hydrogen burn cleanly, and are the subject of a serious research effort. Catalytic converters are now common but continue to be refined, as are fuel additives.

But whatever’s in the fuel tank, you don’t want a thief in the driving seat and there have been many innovations, some using satellite tracking and remote communications, to combat car theft.

These communication systems can also come into play if you crash, automatically calling for help, or may one day alert police to drunk drivers.

Accidents cause many traffic jams, but there are more subtle interplays between vehicles that can cause jams even on a clear but busy road. Such jams can be analysed using statistical tools developed by physicists, and these can produce traffic reports that change in real-time to alleviate congestion.

Robotic drivers could be programmed to make traffic flow more smoothly and will perhaps one day be everyone’s personal chauffeur, but their latest efforts suggest that won’t be soon. More successful, and perhaps even scarier, have been self-swarming robotic traffic cones.

The vaccine is produced by GlaxoSmithKline (GSK) and was tested at low doses on 100 adults. In 80% of them, the vaccine elicited the level of protection required by the agencies that regulate influenza vaccines.

Crucially, this was achieved with two separate doses of just 3.8 micrograms each. Producing the vaccine is difficult and time-consuming, so the lower the dose required, the more people can be treated. In the event of a pandemic, hundreds of millions of doses would be required.

Previous attempts to produce a low dose vaccine had been unsuccessful, with required doses as high as 180 micrograms. Companies then tried adding an adjuvant – a chemical which stimulates the immune system and increases the potency of a vaccine. But, again, results were disappointing.

For example, studies by Sanofi-Pasteur in France and CSL in Australia found that the most common adjuvant, alum, did not help enough. The French study required two vaccine doses of 30 micrograms to achieve a good immune response. CSL got a response with two doses of 15 micrograms each, but only in half of the people tested (see Bird flu vaccine trial gives disappointing results). Vaccines for other bird flu strains work at doses of only 2 micrograms – it is unclear why the deadly H5N1 strain is so different.

Pandemic protection

GSK suggests its success in its trial is due to the use of a novel, proprietary adjuvant. J P Garnier, CEO of GSK, said: “These excellent clinical trial results represent a significant breakthrough. All being well, we expect to make regulatory filings for the vaccine in the coming months.”

He added that GSK would be assessing the vaccine’s ability to offer some protection against other strains of the H5N1 virus. That is important because any pandemic strain that arises will be different to the current strain, which has caused 133 human deaths since 2003.

A number of experts have argued that giving people a vaccine that is not precisely matched at an early stage of a pandemic is more valuable than waiting until a matched vaccine can be produced (see Today’s bird flu vaccines will have to do).

The GSK vaccine was produced from inactivated H5N1 virus. The immune response was gauged using a standard technique which assesses the increase in the number of antibodies an individual produces in response to the vaccine. This is done by measuring the clumping together of red blood cells, which the presence of antibodies inhibits.

New victim

GSK’s announcement came on the same day as Thailand reported its first bird flu death in over seven months. The death raises new fears for the country’s struggling poultry industry and has put health officials on high alert.

The victim was a 17-year-old boy in Pichit, northern Thailand, who caught the virus from one of his fighting cocks. The Thai authorities have banned all movements of poultry in the region, and put seven other provinces on high alert. Three of the boy’s relatives are under surveillance for any symptoms of the virus.

Thailand was previously the world’s largest exporter of poultry but is now ranked fourth. Fears over bird flu led countries around the world to ban trade in raw Thai chicken.

Bird Flu – Learn more about the flu pandemic that could kill millions in our continually updated special report.

The earthquake that generated the wave struck at 1519 local time (0819 GMT), 245 kilometres south of Java’s coast. As more seismological data has been collated, its magnitude has been upgraded from 7.2 to 7.7. The logarithmic scale used means this signifies a fivefold increase in energy from the previous estimate. The earthquake’s depth has also been recalculated, from 45 kilometres to just 10 km.

Local witnesses say that two or three large waves arrived within about 30 minutes of the tremors being felt. The biggest wave was said to be 2 metres tall and smashed into resorts and coastal villages in the region around Pangandaran beach.

According to seismic data posted online by the US Geological Survey (USGS), there had been 20 aftershocks between magnitude 4.9 and 6.3 by 0700 GMT on Tuesday. However, despite reported local scares, no further tsunami waves are expected.

Christmas Islands

An Associated Press report says that another Indonesian island, Sumatra, now has a tsunami alarm system which can alert people to leave coastal areas. But Java’s system is not scheduled to begin operation until 2007, it says.

The nearest land to the earthquake’s epicentre was Australia’s Christmas Islands, 215 km away. The Australian tsunami warning system delivered an alert to residents of the islands 20 minutes before any tsunami was expected to arrive, and about 300 people moved to higher ground.

In the event the highest wave seen at the Christmas Islands was just 60 centimetres tall. The small size of the wave is due to the islands’ volcanic origin, which means they are steep-sided. For a tsunami wave to reach a large height, it needs to roll towards the coast across a continental shelf that gradually gets shallower.

Extremely active

The earthquakes were the result of the Australian tectonic plate, overlain by the Indian Ocean, moving northwards and being thrust under the Sunda plate, upon which Java sits. The Australian plate advances by 59 millimetres every year, relative to the Sunda plate.

This plate boundary is very active. Previous large tremors in the region noted by the USGS include a magnitude 7.8 in 1994 that created a tsunami with a maximum run up height of 13 metres and which killed 200 people. That quake occurred 600 km from Monday’s quake.

And in 1977 a magnitude 8.3 earthquake, 1200 km from Monday’s tremor, produced a tsunami with a maximum run-up height of 15 metres which killed almost 200 people.

The devastating Yogyakarta earthquake, which struck in May 2006 and was magnitude 6.3, occurred at shallow depth within the overriding Sunda plate. It killed over 5000 people as it occurred very close to populated areas.

Indonesia and other places around the Indian Ocean were also struck by a devastating tsunami in December 2004 which killed 235,000 people. See our Asian Tsunami Disaster special report.

The earthquakes had prompted tsunami warnings by the Pacific Tsunami Warning Center and its Japanese equivalent. Sea level gauge data collected by the PTSC showed a tsunami had been generated.

But its report added: “Based on historical earthquake and tsunami data, plus current sea level readings, a more widespread tsunami threat probably does not exist.” Nonetheless, the report concluded that “some areas further from the epicentre could experience small sea level changes and strong or unusual coastal currents”.

The first quake, with a magnitude of 7.2, struck at 0819 GMT. According to seismic data posted online by the US Geological Survey, it occurred about 225 kilometres south of Java, and at a depth of 49 kilometres.

Subduction zone

Just under an hour later, at 0913 GMT, a second tremor was detected at a location very close to the first, this time with a magnitude of 6.1. Earthquakes in this region as caused by the Indian Ocean plate being thrust under the Indonesian plate, a process called subduction.

According to an Associated Press report, the tsunami wave crashed into a beach resort, damaging buildings and sending boats crashing into houses. A witness told a local radio station that she had seen three bodies. Reuters named the resort as Pangandaran Beach.

Indonesia and other places around the Indian Ocean were struck by a devastating tsunami in December 2004. See our Asian Tsunami Disaster special report.

A huge potential crater has been discovered in Antarctica via gravity measurements from space. The find has led geologists to speculate that the huge meteorite that may have caused it prompted the biggest mass extinction in the Earth’s history and caused the break up of an early supercontinent, spawning Australia.

The gravity measurements were obtained by the GRACE satellites and show a 300-mile-wide (483km) structure that is now hidden more than one mile (1.6 km) beneath the East Antarctic Ice Sheet (see diagram).

Ralph von Frese, at Ohio State University in the US, and colleagues say the Wilkes Land crater is more than twice the size of the Chicxulub crater in Mexico’s Yucatan peninsula, which marks the impact that is thought to have killed off the dinosaurs 65 million years ago.

While the meteorite that created the Chicxulub crater is thought to have been six miles (9.6 km) wide, the Antarctic meteorite could have been up to 30 miles wide (48.3 km). But while von Frese is hopeful, the Antarctic structure is not necessarily the result of an impact – it could have been caused by normal volcanic activity. Only rocks samples from the area showing evidence of an impact will resolve the issue.

Softened bruises

Determining when the structure formed is difficult, but the researchers have put rough bounds on the date. The crater is cut by the rift which opened to form the Indian Ocean, meaning it must be older than 100 million years.

And von Frese told żěè¶ĚĘÓƵ that impact craters older than the start of the Cambrian geological period – 543 million years ago – no longer have gravity anomalies. “They are like bruises – big in the beginning but they get smaller with time”, he says, as the crust erodes and creeps to fill in the depression.

In between those two dates, 250 million years ago, the end of the Permian period marked the greatest die-off of species ever seen. Von Frese thinks the discovery of the massive crater that could have been created at the right time is suggestive, but admits there is no proof. Other researchers have suggested a structure off the Australian coast could be an impact crater linked to the Permian mass extinction.

He would like to visit Antarctica to perform gravity and magnetic surveys using a long-range aircraft. Such an expedition would also allow geologists to see whether glaciers draining the basins over the crater have eroded and carried rock samples to the coast.

Big hit

Von Frese also thinks it is possible that the impact actually prompted the break up of the supercontinent Gondwanaland, which created Australia, Africa and India. And he notes that the Siberian traps, a series of huge volcanic eruptions is on exactly the opposite side of the globe from the Antarctic crater.

But he acknowledges that this idea is controversial (see a previous żěè¶ĚĘÓƵ story) and that geologists are far from agreement: “It’s a poorly studied phenomenon.”

They research was reported at a recent American Geophysical Union Joint Assembly meeting in Baltimore, Maryland.

The Mars Reconnaissance Orbiter successfully entered orbit around Mars on Friday, NASA mission controllers have confirmed.

The craft aimed its main thrusters forward and fired them for 27 minutes to slow down by 3540 kilometres per hour (2200 mph), or 18% of its total speed. Failure would have caused Mars Reconnaissance Orbiter (MRO) to fly past the Red Planet.

The mission to study the Martian surface is “the most technologically advanced payload” NASA has ever sent to another planet, says Jim Graf, project manager for MRO.

The orbit insertion was a critical moment in the mission, as two of the last four orbiters NASA sent to Mars did not survive the final approach. Mars Observer spacecraft fell silent on approach in 1993, probably because of a leak caused when its propulsion system was pressurised. And the Mars Climate Orbiter probably broke up in the planet’s atmosphere in 1999 due to a mix up between metric and Imperial units.

Aerobraking phase

The spacecraft will now begin a seven-month “aerobraking” phase. During this phase, it will dip into Mars’s atmosphere hundreds of times, using the friction of atmospheric drag to move from an approximately 35-hour orbit that extends about 35,000 miles (56,000 kilometres) above the planet to a two-hour orbit that skims just 190 miles (300 kilometres) above its surface.

It will then begin a two-year science phase, during which it will collect more data than all of the previous Mars missions combined – 34 trillion bytes of data or about as much as contained by a video store.

The spacecraft will use a suite of six instruments, including the most powerful camera ever sent to another planet. This will image objects as small as 1-metre wide and should be able to snap pictures of the Spirit and Opportunity rovers. The instruments will track the planet’s weather, geology and mineralogy, and even probe about a kilometre beneath its surface to hunt for water.

Relay phase

After the science phase, it will begin its relay phase. During this time it will continue to take some science data but will give priority to relaying data from future Mars missions, such the Phoenix lander due to launch in 2007 and the Mars Science Laboratory (MSL) rover set to launch in 2009.

MRO carries an antenna that will be able to transmit 10 times as much data per minute as any previous spacecraft. The probe’s expected operational lifespan is 10 years.

MRO joins two other US orbiters, Mars Global Surveyor and Mars Odyssey, and one European craft, Mars Express, that are already looking for signs of water and ice on the Red Planet.