A gargantuan explosion ripped apart a star perhaps 150 times more massive than our sun in a relatively nearby galaxy in the most powerful and brightest supernova ever observed, astronomers said on Monday.

And there is one such star in our own Milky Way galaxy that appears to be on the brink of dying in just such a supernova.

The exploding star's dramatic death may have come in a rare type of supernova reserved for "freakishly massive" stars that astronomers had speculated about but never previously witnessed.

The supernova, designated as SN 2006gy, occurred 240 million light years away in a galaxy called NGC 1260, and was studied using observations from NASA's orbiting Chandra X-ray Observatory as well as earthbound optical telescopes.

Virgin Galactic today unveiled the design of its new, environmentally benign, space launch system based on the X Prize winning technology of SpaceShipOne, which successfully flew into space for the third time in October 2004 and won the $10m Ansari X Prize. The construction of the White Knight Two (WK2) mothership, or carrier aircraft, is now very close to completion at Scaled Composites in Mojave, CA and is expected to begin flight testing in the summer of 2008.

It is the world's largest, all carbon composite aircraft; it has a unique high altitude lift capacity, capable of launching SpaceShipTwo and its eight astronauts into sub-orbital space flight. The WK2 mothership is powered by four Pratt and Whitney PW308A engines which are amongst the most powerful, economic and efficient engines available. The WK2 mothership has also been designed to be capable of lifting other payload and launching it into space. Whilst the two vehicles comprising the space launch system have been under construction, Virgin Galactic's cadre of future astronauts has continued to grow strongly to well in excess of 200 individuals with around 85,000 registrations of interest to fly. Astronaut orientation for spaceflight is progressing well and already 80 of SpaceShipTwo's first passengers have been through medical assessment and centrifuge training at the NASTAR facility in Philadelphia.

Commenting on the unveiling, Burt Rutan, CEO of Scaled Composites, said: "Virgin Galactic produced a demanding output specification for the world's first private human and payload space launch system. This required us to produce a safe but flexible design capable of multiple applications in new market sectors. I am confident that these vehicles, now in an advanced stage of construction, will achieve just that. I would like to take this opportunity to thank the whole team at Scaled Composites. "Looking up - way up!" is an expression we have shared since the X Prize began and now we are all excited that this year the dream will start to become a very tangible reality for everyone involved."

Sir Richard Branson, Founder of Virgin Galactic, added: "The designs of both the mothership and the new spaceship are absolutely beautiful and surpass any expectations for the future of commercial spaceflight that we had when first registering the name Virgin Galactic in 1999. Burt and his team have done a fantastic job and I am also delighted with the wonderful vision that Foster and Partners, working with URS, have shown in the final designs for Spaceport America in New Mexico. Finally, we are all very excited about the prospect of being able to develop a bio-fuel solution for the space launch system and we are looking forward to working with Pratt and Whitney and Virgin Fuels to trial an appropriate bio mix for the PW308A engines that will be powering our new carrier aircraft."

Virgin Galactic will make further announcements regarding the progress of the launch system, development of its markets, the test flying program and start of commercial operations at Spaceport America in due course.

They were searching for pulsars -- a type of rotating compacted neutron star that sends out rhythmic pulses of radiation -- when they spotted the giant radio signal.

It was extremely brief but very strong, and appears to have come from about 3 billion light-years away -- a light-year being the distance light travels in a year, or about 6 trillion miles.

"This burst appears to have originated from the distant universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said Duncan Lorimer of West Virginia University and the National Radio Astronomy Observatory.

It is, however, unlikely to be the extraterrestrial equivalent of "I Love Lucy" or other radio or television broadcast.

"It's much too bright. There is no way any civilization that we could possibly think of could create a thing so incredibly powerful," she said.

The crewmembers aboard the space station took a short break Saturday to get a look at the storm from their vantage point. Even from space, the storm expected to reach the Gulf of Mexico Aug. 21 and gain strength as a potential Cat 5 storm, impresses the crew with its size.

Gliese 581 C is the smallest extrasolar planet, or "exoplanet," discovered to date. It is located about 15 times closer to its star than Earth is to the Sun; one year on the planet is equal to 13 Earth days. Because red dwarfs, also known as M dwarfs, are about 50 times dimmer than the Sun and much cooler, their planets can orbit much closer to them while still remaining within their habitable zones, the spherical region around a star within which a planet's temperature can sustain liquid water on its surface.

Because it lies within its star's habitable zone and is relatively close to Earth, Gliese 581 C could be a very important target for future space missions dedicated to the search for extraterrestrial life, said study team member Xavier Delfosse of Grenoble University in France.

"On the treasure map of the universe, one would be tempted to mark this planet with an X," Delfosse said.

Two other planets are known to inhabit the red dwarf system. One is a 15 Earth-mass "hot-Jupiter" gas planet discovered by the same team two years ago, which orbits even closer to its star than does Gliese 581 C. Another is an 8 Earth-mass planet discovered at the same time as Gliese 581 C, but which lies outside its star's habitable zone.

"By reaching this dream I've had since childhood, I hope to tangibly demonstrate to young people all over the world that there is no limit to what they can accomplish," said Anousheh Ansari, chairman and co-founder of Prodea Systems, Inc., a revolutionary digital home technology company that is sponsoring her efforts. "I'm thankful to both Space Adventures and Dice-K Enomoto for providing me this opportunity."

"We are pleased to announce this historic event, the world's first female space tourist, and are overjoyed that Anousheh is ready for flight. She has been training diligently for several months now and has been certified for flight," said Eric Anderson, president and CEO of Space Adventures. "We celebrate Anousheh's dedication in her spaceflight preparations and wish her a successful and awe-inspiring mission."

Claims of the possibility of "gravity reduction" or "anti-gravity" induced by magnetic fields have been investigated by NASA before (New Scientist, 12 January 2002, p 24). But this one, Droscher insists, is different. "Our theory is not about anti-gravity. It's about completely new fields with new properties," he says. And he and Hauser have suggested an experiment to prove it.

This will require a huge rotating ring placed above a superconducting coil to create an intense magnetic field. With a large enough current in the coil, and a large enough magnetic field, Droscher claims the electromagnetic force can reduce the gravitational pull on the ring to the point where it floats free. Droscher and Hauser say that to completely counter Earth's pull on a 150-tonne spacecraft a magnetic field of around 25 tesla would be needed. While that's 500,000 times the strength of Earth's magnetic field, pulsed magnets briefly reach field strengths up to 80 tesla. And Droscher and Hauser go further. With a faster-spinning ring and an even stronger magnetic field, gravitophotons would interact with conventional gravity to produce a repulsive anti-gravity force, they suggest.

Dröscher is hazy about the details, but he suggests that a spacecraft fitted with a coil and ring could be propelled into a multidimensional hyperspace. Here the constants of nature could be different, and even the speed of light could be several times faster than we experience. If this happens, it would be possible to reach Mars in less than 3 hours and a star 11 light years away in only 80 days, Droscher and Hauser say.

The US military is considering testing the principle behind a type of space drive which holds the promise of reaching Mars in just three hours. The problem is, as New Scientist explains, it's entirely theoretical and many physicists admit they don't understand the science behind it.

"I'm very confident we will have samples in there that are the first returned from beyond the Moon," former Stardust project manager, Ken Atkins, told the BBC News website.

"It is magnificent to see something that we saw leave the planet on 7 February 1999 return to the planet here on 15 January 2006."

The highlight of Stardust's seven-year mission was its close encounter with Comet Wild 2 in January 2004.

Gerstenmaier said the foam investigation was making "very good progress," but that it was still unclear exactly what had gone wrong.

In addition to the foam repairs, NASA said the delay would allow it to shift the shuttle order around so that Atlantis would not be forced to make two missions in a row, with a quick turnaround. Now that there's a seven-month delay, Discovery will take on STS-121, the next scheduled mission, and Atlantis will take the one after that, STS-115, currently set for May 2006.

NASA Administrator Mike Griffin said he did not think the delays would greatly impact the five-year plan to finish building the international space station and then retire the shuttle. "We need to view shuttle missions as a process," he said, instead of focusing on individual missions in isolation.

Discovery spent two weeks in space, where the crew demonstrated new methods to inspect and repair the Shuttle in orbit. The crew also delivered supplies, outfitted and performed maintenance on the International Space Station. A number of these tasks were conducted during three spacewalks.

In an unprecedented event, spacewalkers were called upon to remove protruding gap fillers from the heat shield on Discovery's underbelly. In other spacewalk activities, astronauts installed an external platform onto the Station’s Quest Airlock and replaced one of the orbital outpost’s Control Moment Gyroscopes.

Inside the Station, the STS-114 crew conducted joint operations with the Expedition 11 crew. They unloaded fresh supplies from the Shuttle and the Raffaello Multi-Purpose Logistics Module. Before Discovery undocked, the crews filled Raffeallo with unneeded items and returned to Shuttle payload bay.

Shortly after Discovery lifted off July 26, a 1-pound chunk of foam insulation fell from the fuel tank — the very thing that doomed Columbia. The foam missed Discovery, but NASA grounded all shuttle flights until engineers fix the problem.

"We're going to try as hard as we can to get back in space this year," NASA Administrator Michael Griffin said at a post-landing news conference. "But we’re not going to go until we're ready to go."

The final issue of concern -- a torn thermal blanket just below the cockpit window that might shed bits of debris during the shuttle's descent -- was cleared off the table Thursday morning after a series of wind-tunnel tests, said deputy shuttle program manager Wayne Hale, who heads Discovery's mission management team.

The tests indicated that even if pieces of cloth debris blew off and struck the aft section of the orbiter, it would be "of negligible concern" and pose no threat to Discovery's safe landing, he said. Under those circumstances, sending spacewalkers out to snip away the torn section would have violated the "first, do no harm" rule, Hale said.