Wednesday, August 27, 2008

Solar Powered Aircraft


The solar-powered Zephyr aircraft developed by the UK defence and technology firm QinetiQ has completed the longest-lasting unmanned flight.

The Zephyr has ultra-light wings, and flew for three-and-a-half-days in a test flight above the Yuma Proving Ground, Arizona.

The project's technical director, Chris Kelleher, says the solar plane charges its batteries for night flight and could stay aloft for months on end.


Watch the video here:
http://news.bbc.co.uk/2/hi/science/nature/7575158.stm

Black hole star mystery 'solved'

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7574255.stm
Astronomers have shed light on how stars can form around a massive black hole, defying conventional wisdom.

Scientists have long wondered how stars develop in such extreme conditions.

Molecular clouds - the normal birth places of stars - would be ripped apart by the immense gravity, a team explains in Science magazine.

But the researchers say stars can form from elliptical discs - the relics of giant gas clouds torn apart by encounters with black holes.

They made the discovery after developing computer simulations of giant gas clouds being sucked into black holes like water spiralling down a plughole.

"These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the galaxy," said co-author Ian Bonnell from St Andrews University, UK.

Ripped apart

Their findings are in accordance with actual observations in our Milky Way galaxy that indicate the presence of a massive black hole, surrounded by huge stars with eccentric orbits.

The simulations, performed on a supercomputer - and taking over a year of computing time - followed the evolution of two separate giant gas clouds up to 100,000 times the mass of the Sun, as they fell towards the supermassive black hole.

The simulations show how the clouds are pulled apart by the immense gravitational pull of the black hole.

The disrupted clouds form into spiral patterns as they orbit the black hole; the spiral patterns remove motion energy from gas that passes close to the black hole and transfers it to gas that passes further out.

This allows part of the cloud to be captured by the black hole while the rest escapes.

In these conditions, only high mass stars are able to form and these stars inherit the eccentric orbits from the elliptical disc.

These results match the two primary properties of the young stars in the centre of our galaxy: their high mass and their eccentric orbits around the supermassive black hole.

"That the stars currently present around the galaxy's supermassive black hole have relatively short lifetimes of [about] 10 million years, which suggests that this process is likely to be repetitive," Professor Bonnell explained.

"Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may help us understand the origin of supermassive black holes in our and other galaxies in the Universe."

Computer viruses make it to orbit

A computer virus is alive and well on the International Space Station (ISS).

Nasa has confirmed that laptops carried to the ISS in July were infected with a virus known as Gammima.AG.

The worm was first detected on earth in August 2007 and lurks on infected machines waiting to steal login names for popular online games.

Nasa said it was not the first time computer viruses had travelled into space and it was investigating how the machines were infected.

Orbital outbreak

Space news website SpaceRef broke the story about the virus on the laptops that astronauts took to the ISS.

Nasa told SpaceRef that no command or control systems of the ISS were at risk from the malicious program.

The laptops infected with the virus were used to run nutritional programs and let the astronauts periodically send e-mail back to Earth.

The laptops carried by astronauts reportedly do not have any anti-virus software on them to prevent infection.

Once it has scooped up passwords and login names the Gammima.AG worm virus tries to send them back to a central server. It targets a total of 10 games most of which are popular in the Far East such as Maple Story, HuangYi Online and Talesweaver.

Nasa is working with partners on the ISS to find out how the virus got on to the laptop in the first place.

The ISS has no direct net connection and all data traffic travelling from the ground to the spacecraft is scanned before being transmitted.

It is thought that the virus might have travelled via a flash or USB drive owned by an astronaut and taken into space.

The space agency also plans to put in place security systems to stop such incidents happening in the future.

Nasa told Wired News that viruses had infected laptops taken to the ISS on several occasions but the outbreaks always only been a "nuisance".