Space is fizzing. Above our heads, where the Earth's magnetic field meets the constant stream of gas from the Sun, thousands of bubbles of superheated gas are constantly growing and popping.

Their discovery could allow scientists to finally understand the interaction between the solar wind and the Earth's magnetic field.

This exciting new view of near-Earth space has been made possible by ESA's four-spacecraft flotilla, Cluster, and Double Star, ESA's collaborative space mission with China. The spacecraft encounter the bubbles every time they are on the day-lit side of the Earth, at altitudes of between 13 and 19 Earth radii.

The bubbles, known as density holes, are regions of space where the density of gas suddenly falls by ten times but the temperature of the remaining gas leaps from 100 000 ºC to 10 000 000 ºC.

When Cluster first flew through the bubbles, George Parks, University of California, Berkeley, thought that they were just instrumentation glitches. "Then I looked at the data from all four Cluster spacecraft. These anomalies were being observed simultaneously by all the spacecraft. That's when I believed that they were real," says Parks.

Somewhat similar bubbles have occasionally been encountered in the past by other spacecraft. They were called hot flow anomalies but Parks decided the bubbles he saw are significantly different.

He found their signature in Double Star data too. During every orbit, the spacecraft usually fly through 20-40 bubbles. By carefully correlating the different spacecraft readings, Parks and his collaborators learnt that the bubbles expand to about 1 000 kilometres and probably last about 10 seconds before bursting and being replaced by the cooler, denser solar wind.

Space around Earth is fizzing
The energy source to drive these bubbles is currently uncertain but there is strong circumstantial evidence that the collision of the solar wind with the Earth's magnetic field, which forms a boundary known as the bow shock, is probably creating the energy to drive them.

Bow shocks exist throughout nature. The familiar place is at the front of a ship; the bow shock is the swell of white water that builds up and precedes the boat. Another is in supersonic air travel. As an aircraft flies faster than the speed of sound, the sound waves pile up in front of the plane. That energy is finally dissipated in the sonic boom that occurs.

The bow shock between the Earth's magnetic field and the solar wind is similar in many respects. The big difference is that scientists do not know how the energy in the magnetic bow shock is dissipated. This is to say they do not know what the equivalent of the sonic boom is. The newly discovered bubbles might provide a clue.

It is possible that they are caused by the energy that piles up at the bow shock - however, being certain is a long way off yet.

"For now, our job is to study them as thoroughly as possible. Then we will try to simulate them on computers and finally we will know what effect they have," concludes Parks.

Critics said the reference underscores the Pentagon's failing policies on gays, and adds to a culture that has created uncertainty and insecurity around the treatment of homosexual service members, leading to anti-gay harassment.

Pentagon spokesman Lt. Col. Jeremy M. Martin said the policy document is under review.

The Pentagon has a "don't ask, don't tell" policy that prohibits the military from inquiring about the sex lives of service members but requires discharges of those who openly acknowledge being gay.

The Center for the Study of Sexual Minorities in the Military, at the University of California at Santa Barbara, uncovered the document and pointed to it as further proof that the military deserves failing grades for its treatment of gays.

Nathaniel Frank, senior research fellow at the center, said, "The policy reflects the department's continued misunderstanding of homosexuality and makes it more difficult for gays and lesbians to access mental health services."

The document, called a Defense Department Instruction, was condemned by medical professionals, members of Congress and other experts, including the American Psychiatric Association.

"It is disappointing that certain Department of Defense instructions include homosexuality as a 'mental disorder' more than 30 years after the mental health community recognized that such a classification was a mistake," said Rep. Marty Meehan, D-Mass.

Congress members noted that other Pentagon regulations dealing with mental health do not include homosexuality on any lists of psychological disorders. And in a letter to Defense Secretary Donald H. Rumsfeld on Monday, nine lawmakers asked for a full review of all documents and policies to ensure they reflect that same standard.

"Based on scientific and medical evidence the APA declassified homosexuality as a mental disorder in 1973 - a position shared by all other major health and mental health organizations based on their own review of the science," James H. Scully Jr., head of the psychiatric association, said in a letter to the Defense Department's top doctor earlier this month.

There were 726 military members discharged under the "don't ask, don't tell" policy during the budget year that ended last Sept. 30. That marked the first year since 2001 that the total had increased. The number of discharges had declined each year since it peaked at 1,227 in 2001, and had fallen to 653 in 2004.

Six smaller tombs had eroded away leaving no indications of their original scale and appearance, but the biggest tomb, located on the south side of the mountain, could clearly be discerned as a pyramid shape with three layers from bottom to top.

The pyramid's square bottom is about 50 meters long and 30 meters wide, about the size of a basketball court, with an oval platform on the top, about 15 meters long and 10 meters wide. The tomb was made of stone and earth dug out from the hill.

A stone coffin, surrounded by four screen boards and covered by a granite top, was placed on the top platform.

The coffin appeared to belong to the king of an early tribe based on the dimensions of the site, according to experts with the Jiaohe Archaeological Research Institute.

The tombs are part of the Xituanshan cultural ruins site, which dates back 3,000 years to China's Bronze Age period. The ruins were excavated in Jilin in 1950.

A lot of ancient hunting and domestic tools, including a stone knife and axe, as well as bronzeware and earthenware, have been unearthed from the stone coffin and other six smaller graves.

The discovery will provide valuable clues on study of ancient funeral customs and the tomb structure and culture of ethnic groups in the area.

"Other high risk exercises are slaughtering of sick birds, de-feathering and preparing food. But if you wash your hands, it can reduce that risk very dramatically," he said. "But again, this is less often done by the younger person than adult."

The H5N1 virus has infected 51 people and killed 39 of them in Indonesia since 2005 and is now endemic in poultry in nearly all of the country's 33 provinces.

It is common in the far-flung country of 17,000 islands for households to keep chickens for food and extra income - which means that everyone, and not just poultry workers, is at risk.

School-age children and children less than 10 years of age make up over 40 percent of Indonesia's H5N1 human infections. People are not used to the idea that sick birds could be dangerous and children play with chickens and are sent to clean up after them.

"It shows that the risk profile is much broader than we expected. It's not only poultry workers. This is because the virus is found so widely in backyard chicken," said Steven Bjorge, WHO's medical officer of communicable diseases.

"There were other diseases in birds but they did not cross over to humans in the past. That's the situation that they are not familiar with," he said.

"People need to understand that dead chickens are a high risk factor. If there is dead chicken, they need to call the authority to clean them properly and should not let children touch them."

NOT JUST INDONESIA

In Hong Kong, where the virus made its first documented jump to humans in 1997, nine of the 18 human infections involved children who were six years old or younger.

The first victim was a three-year-old boy who died 12 days after he developed fever, a sore throat and a cough in May, 1997. While experts never confirmed how he came to be infected, he attended a nursery which kept chicks and ducklings in a pet zoo.

At least two other children attended a school that was next to a wholesale market and often played in an area used to store chicken cages that were unwashed and splattered with feces.

H5N1 infected birds shed plenty of virus in their feces and experts say stool particles are a main vehicle of transmission. Kept moist and cool, the virus can survive for days on feces.

"If chickens infected with H5N1 are shedding the virus in their feces on the floor of houses where people live, then they are more likely to be exposed to H5N1 infection," said Julian Tang, a microbiologist at Chinese University in Hong Kong.

"The virus may survive for some time in the chicken feces, then when dry, can be inhaled as dust. This may occur if the feces on the floor is disturbed by walking, playing. You can breathe or have direct contact with it, when you are just present in the area, whether sleeping or doing other things."

"Children are probably more vulnerable because they tend to play on the floor, more often, where the risk of contact with such infected material is higher. If they are sent to clean up dead chickens, well, you have your answer," Tang said.

Ignorance is also believed to have played a role in the deaths of four young Azerbaijanis in February and March, who de-feathered dead swans to make pillows before they fell sick.

Feathers too may infected an 18-year-old Indonesian shuttlecock maker, who died last month. While officials have not said how he got infected, he sorted feathers for a living.

"Infected birds preen their feathers which could be contaminated with beak excretions. The virus would then be transferred to the person by hand or breathing in feather dust contaminated with virus," said John Oxford, virology professor at the Royal London Hospital.

Girgenti said an officer fired back while trying to escape the shooting. He declined to comment on whether the shooter was among the victims. Tallahassee police said earlier that the shooter was in custody.

The condition of the survivor and identities of the victims were not immediately released.

It also wasn't immediately clear why the six guards were being arrested; Girgenti said he didn't have details about what the warrants involved.

"The community is safe. The institution is in lockdown status," federal Bureau of Prisons spokeswoman Carla Wilson said.

The detention center houses mostly men and is part of the Tallahassee Federal Correctional Institution. A low security prison for female inmates is next to the detention center. Together the men's and women's units total 1,445 inmates.

Among the few items salvaged was half a shipping container of goods bound for a missionary project in Haiti. Another container headed for missionaries at an African university also was saved.

Insurance won't cover much of the losses, said Curtis Wilke, the nonprofit's executive director.

"Just Thursday a retired doctor gave us his entire office full of medical equipment," Wilke said. "Now it's all gone."

Another nonprofit group has set up a phone bank to help Wilke's alliance recover.

"I imagine some people are going to be missing some meals," said Reuben Sanchez, head of the men's ministry for Somebody Cares.