Space, Astronomy & Astrophysics Various

Θέμα: Space, Astronomy & Astrophysics Various 13.11.10 13:20

Astronomers Find Massive, Previously Undetected Gamma Radiation Bubbles Adorning the Milky Way

Space, Astronomy & Astrophysics Various 498887mainfermibubblear

Space, Astronomy & Astrophysics Various 498887mainfermibubblear

The Milky Way's Newly Discovered Gamma-Ray Bubbles NASA's Goddard Space Flight Center

A Harvard astronomer and his team have turned up something quite big while running publicly available data from NASA’s Fermi Gamma-ray Space Telescope, and by big we mean both in scientific magnitude and in astronomical size: two massive gamma-ray emitting bubbles extending 25,000 light-years both north and south of the Milky Way’s center. The researchers aren’t sure where they come from or why they’re there, but the discovery of this massive new structure in the heart of our own galaxy is being equated to discovering a new continent on Earth.

Viewed from Earth the structure spans half the sky, but previous examinations of the data – which came from Fermi’s Large Area Telescope (LAT) – didn’t reveal the structure because it couldn’t bee distinguished from diffuse emission, a fog of gamma rays that appears across the entire sky.

See the video

star

Θέμα: Απ: Space, Astronomy & Astrophysics Various 13.11.10 13:24

In First Test of Interstellar GPS, Team Uses Distant Pulsars to Determine Position in Space

Space, Astronomy & Astrophysics Various 800pxpulsarmodel4567632

Space, Astronomy & Astrophysics Various 800pxpulsarmodel4567632

Pulsar Positioning It beats rolling down the window and asking for directions. NASA

Global Positioning Systems work famously here on the home planet because we control all of the moving parts; put some satellites in the sky, equip a device with the proper hardware to communicate with them, and you can locate yourself just about anywhere. But how would we locate ourselves in deep space? For that kind of spatial location, a team of Italian researchers have devised a way to calculate one’s position in space using pulsars as interstellar navigation beacons.

The idea of using pulsars as a kind of space GPS has been proposed in the past;
but Matteo Ruggerio and some colleagues at the Politecnico di Torino are the first to have actually done it, using the radio telescope-equipped Parkes Observatory in Australia as their reference point.

GPS is nothing more than the measurement of time-delay measurements relative to different satellite clocks, and pulsars – rotating neutron stars that emit beams of radio waves – are extremely precise clocks. Because they are rotating very regularly, those radio beams appear to be pulsing at regular intervals as well, intervals so regular that they rival atomic clocks in their precision. But the high speeds at which astronomic bodies move makes calculating position from various pulsars pretty difficult.

Part of the problem with pulsar-based space positioning systems (SPS? Can we go ahead and coin that acronym?) is that you have to monitor more than one pulsar at a time to accurately calculate position. Parkes can only monitor one at a time. So the team used a software package called TEMPO2 to simulate the signals that known pulsars would produce anywhere on Earth.

Crunching all of that data together, they were able to get what they call “a correct result with a poor accuracy” after measuring for three days. Meaning that, compared to other methods of measuring the Earth’s position in space, they were certainly in the ballpark but not perfectly precise. But if a continuous stream of data is assumed, that accuracy improves to within a few hundred meters. Considering this is a relativistic positioning scheme – relative to objects scattered across the galaxy – that’s relatively close.

star

Θέμα: Απ: Space, Astronomy & Astrophysics Various 13.11.10 13:27

Scientists Map Out Gravitational Space Highways

Space, Astronomy & Astrophysics Various Gravitationalcorri47466

Gravity Super Highway via The Daily Telegraph

As planets of our solar system tug at each other with their gravitation tethers, they create a protean sea of forces and counter forces. But within that maelstrom lay gravitational channels that could serve as highways for future spacecraft, just as soon as Professor Shane Ross of from Virginia Tech University finishes mapping them out.

Located at the exact points between planets where the bodies exert an equal gravitation pull, these channels act like invisible ocean currents in a black, featureless sea. A space craft that maneuvers into these lanes could be pulled along to its intended destination by gravity, not pushed there by a rocket. This means the craft could reach a distant planet using considerably less fuel, or could get there much faster with the same amount of fuel.

NASA has already rode these currents once--the Genesis probe followed a gravitational channel en-route to collecting solar dust in 2004. By following the gravitational current, Genesis reached its mission point with ten times less fuel than it would have needed otherwise.

Speaking at the British Science Festival at the University of Surrey in Guildford, Ross highlighted the convenience of these gravity tubes, but also noted that they must be utilized in conjunction with regular rockets. For instance, riding a gravity channel from Earth to Mars without any other boosts would take a couple thousand years.

However, by complimenting conventional propulsion, a completed map of these gravity highways could speed up and expand space travel much like a more accurate understanding of ocean and wind currents aided 15th and 16th century European exploration.

[via The Daily Telegraph]

star

Θέμα: Απ: Space, Astronomy & Astrophysics Various 13.11.10 13:32

Astronomers Spot a Comet Giving Birth

Space, Astronomy & Astrophysics Various Holmesfilter5110857

Baby Blue Comet Comet Holmes displays an expanding dust cloud (left) and some finer structures within the debris (right) David Jewitt

Scientists recently spotted a swarm of baby comets flying away from a passing parent comet -- the largest comet birth ever witnessed. The discovery was assisted by a special digital filter that enhances faint features within the cloud of comet debris.

Comet 17P/Holmes first gained attention in 2007 with an outburst that brightened by a million times in less than a day, and threw off a dust cloud that grew larger than the sun in the eyes of Earth telescopes. But a team of researchers from the University of California, Los Angeles and the University of Hawaii focused on small fragments that seemed to detach from the comet nucleus.

"Initially we thought this comet was unique simply because of the scale of the outburst," said Stevenson. "But we soon realized that the aftermath of the outburst showed unusual features, such as these fast-moving fragments, that have not been detected around other comets."

The astronomers took images over nine nights in November 2007 at the Canada-France-Hawaii Telescope in Hawaii. Their special weapon was a Laplacian filter that sharply enhances discontinuities within images.

That allowed the team to spot many small objects zipping away at speeds up to 280 mph. The brightness of the objects revealed them as baby comets creating their own dust clouds as surface ice vaporized and transformed directly into gas.

Astronomers remain puzzled over the exact cause of cometary outbursts. Some speculate that internal pressure builds up when sub-surface ice evaporates as comets move closer to the sun, and eventually leads to the pressure outburst that spews out a cloud of dust and gas.

More oohing and aahing should ensue at the European Planetary Science Congress in Potsdam, Germany, where more findings on the comet babies are being presented today. Comet Holmes should return for another photo op when it makes its closest approach to the sun in 2014, after a six-year journey.

star

Θέμα: Απ: Space, Astronomy & Astrophysics Various 13.11.10 13:37

DARPA Wants A Few Good Space Debris Cleaners

Space, Astronomy & Astrophysics Various Battleofcoruscat5290460

Futuristic Orbital Cleanup Gentlemen, let's plow the road Lucasfilm

Mad science agency DARPA has a new addition to its wish list: technology to clean up thousands of pieces of orbiting space junk. Surely, world peace can't come far behind on the agenda.

Satellites and manned missions alike have had to dodge a growing swarm of orbital debris in recent years. The U.S. Space Surveillance Network has detected more than 35,000 man-made objects since the space age began over 50 years ago, with 20,000 such objects currently remaining in orbit.

DARPA also noted that the number of cataloged debris objects has actually jumped by almost 50 percent since January 2007. That uptick in space junk comes courtesy of the Chinese government destroying a satellite in 2007, and a collision between an active U.S. satellite and a retired Russian communications satellite this year.

In a perhaps belated response, the Pentagon agency issued a call for possible cleanup proposals yesterday. It noted a special interest in debris ranging from 1 mm crumbs to entire derelict spacecraft and used rocket segments, and asked for a general cleanup timetable ranging from days to years.

The Register reports that U.S. aerospace giant Boeing has already listed itself as an "interested vendor" for the project. Also on the list for the busy bees at Boeing -- morphing helicopter blades and figuring out how to control robot swarms with simple body motions.

There's already a few proposals floating out there for taking down orbital debris, such as a giant parachute shroud that can mercifully end a satellite's life without adding to the space junkyard. But if the U.S. Air Force Command gets its electronic "space fence" upgrade to track all orbital objects greater than two inches, the cleanup job could become just that much more daunting.

[via The Register]

star

Θέμα: Απ: Space, Astronomy & Astrophysics Various 13.11.10 16:41

NASA Catches Two Black Holes Sucking Face

Space, Astronomy & Astrophysics Various Blackholecollision63665

The Chandra X-ray Observatory helped discover two merging black holes a mere 3,000 light years apart

Black Hole Merger: Two pinpoints of light represent black holes in the center of this combined X-ray/optical image NASA/CXC/MIT/C.Canizares, M.Nowak/STScI
Colliding black holes may prove more interesting to scientists than the immovable object versus the unstoppable force. New data from NASA's Chandra X-ray Observatory has combined with optical images from Hubble to show off a merging black hole pair in all its glory.

Chandra findings first led astrophysicists to pinpoint the two black holes in 2002. The black holes sit just 3,000 light years apart from one another in the NGC 6240 system, after a 30-million year cosmic dance that has brought them spiraling in closer to one another. They should ultimately merge into a super-massive black hole some tens or hundreds of millions of years from now.

Scientists believe that pairs of massive black holes can help explain the quirky behavior of super-massive black holes, which may form during common galaxy mergers and collisions. Many galaxies such as our own Milky Way contain a supermassive black hole in the center.

Such interest in gigantic mergers might explain why researchers have simulated black hole threesomes in the past. Not that there's anything wrong with it.

[NASA]

star

» Astronomy picture of the day
» Universe Sandbox : Interactive Space Simulator