Sometimes I complain about the earthly weather, but mostly I like to post about astronomy and space events. Hope you enjoy the articles.
By: Susie77, 7:37 PM GMT on January 28, 2011
By: Susie77, 10:02 PM GMT on January 24, 2011
From Science @ NASA
Solar Sail Stunner
January 24, 2011 : Call it a stunner.
In an unexpected reversal of fortune, NASA's NanoSail-D spacecraft has unfurled a gleaming sheet of space-age fabric 650 km above Earth, becoming the first-ever solar sail to circle our planet.
"We're solar sailing!" says NanoSail-D principal investigator Dean Alhorn of the Marshall Space Flight Center in Huntsville, AL. "This is a momentous achievement."
NanoSail-D spent the previous month and a half stuck inside its mothership, the Fast, Affordable, Science and Technology SATellite (FASTSAT). FASTSAT was launched in November 2010 with NanoSail-D and five other experiments onboard. High above Earth, a spring was supposed to push the breadbox-sized probe into an orbit of its own with room to unfurl a sail. But when the big moment arrived, NanoSail-D got stuck.
"We couldn't get out of FASTSAT," says Alhorn. "It was heart-wrenching—yet another failure in the long and troubled history of solar sails."
Team members began to give up hope as weeks went by and NanoSail-D remained stubbornly and inexplicably onboard. The mission seemed to be over before it even began.
And then came Jan. 17th. For reasons engineers still don't fully understand, NanoSail-D spontaneously ejected itself. When Alhorn walked into the control room and saw the telemetry on the screen, he says "I couldn't believe my eyes. Our spacecraft was flying free!"
The team quickly enlisted amateur radio enthusiasts Alan Sieg and Stan Sims at the Marshal Space Flight Center to try to pick up NanoSail-D's radio beacon.
"The timing could not have been better," says Sieg. "NanoSail-D was going to track right over Huntsville, and the chance to be the first ones to hear and decode the signal was irresistible."
Right before 5pm CST, they heard a faint signal. As the spacecraft soared overhead, the signal grew stronger and the operators were able to decode the first packet. NanoSail-D was alive and well.
"You could have scraped Dean off the ceiling. He was bouncing around like a new father," says Sieg.
The biggest moment, however, was still to come. NanoSail-D had to actually unfurl its sail. This happened on Jan. 20th at 9 pm CST.
Activated by an onboard timer, a wire burner cut the 50lb fishing line holding the spacecraft's panels closed; a second wire burner released the booms. Within seconds they unrolled, spreading a thin polymer sheet of reflective material into a 10 meter-square sail.
Only one spacecraft has done anything like this before: Japan's IKAROS probe deployed a solar sail in interplanetary space and used it to fly by Venus in 2010. IKAROS is using the pressure of sunlight as its primary means of propulsion—a landmark achievement, which has encouraged JAXA to plan a follow-up solar sail mission to Jupiter later this decade.
NanoSail-D will remain closer to home. "Our mission is to circle Earth and investigate the possibility of using solar sails as a tool to de-orbit old satellites and space junk," explains Alhorn. "As the sail orbits our planet, it skims the top of our atmosphere and experiences aerodynamic drag. Eventually, this brings it down."
Indeed, mission planners expect NanoSail-D to return to Earth, meteor-style, in 70 to 120 days.
If this works (and there is little doubt that it will), NanoSail-D could pave the way for a future clean-up of low-Earth orbit. Drag sails might become standard issue on future satellites. When a satellite's mission ends, it would deploy the sail and return to Earth via aerodynamic drag, harmlessly disintegrating in the atmosphere before it reaches the ground. Experts agree that something like this is required to prevent an exponential buildup of space junk around Earth.
Alhorn and colleagues will be monitoring NanoSail-D in the months ahead to see how its orbit decays. They'd also like to measure the pressure of sunlight on the sail, although atmospheric drag could overwhelm that effect.
No matter what happens next, NanoSail-D has already made history: It has demonstrated an elegant and inexpensive method for deploying sails and become the first sail to orbit Earth. Eventually, the team will diagnose the sail’s reluctance to leave FASTSAT—"and then we'll be batting a thousand," says Alhorn.
A follow-up story on Science@NASA will explain how sky watchers can track and photograph NanoSail-D before it returns to Earth. Stay tuned for "Solar Sail Flares."
By: Susie77, 7:16 PM GMT on January 19, 2011
Yippee, a Winter Storm Warning for STL!!!
By: Susie77, 12:13 AM GMT on January 11, 2011
Updated: 3:27 PM GMT on January 11, 2011
By: Susie77, 5:19 PM GMT on January 06, 2011
Courtesy Space dot com
Lagoon Nebula's Stellar Baby Boom Seen in New Photo
By SPACE.com Staff
posted: 05 January 2011
06:31 am ET
A gorgeous new image from the European Southern Observatory reveals the glowing, blue Lagoon Nebula – a hotbed of star birth – amid a backdrop speckled with bright stars.
The seemingly mystical Lagoon Nebula is a budding star nursery also known as Messier 8. It is approximately 4,000 to 5,000 light-years from Earth in the constellation of Sagittarius (the Archer).
The new infrared view of the nebula was captured as part of a five-year study of our Milky Way galaxy using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) at the Paranal Observatory in Chile. The photo is just a small portion of a much larger image, and a wider survey, of the region surrounding the nebula.
Mapping the universe
Astronomers are using the VISTA telescope to scour our galaxy's central regions for new variable objects. The survey is also aimed at mapping the Milky Way's structure in greater detail than ever before.
Observations in the infrared wavelength can be a boon for astronomers because they are able to peer behind the veil of dust that would normally prevent celestial objects from being seen in visible light. This is because visible light, which has a wavelength that is roughly the same size as the dust particles, is strongly scattered.
Infrared light, on the other hand, has a longer wavelength and can pass through the dust largely unscathed.
ESO's VISTA telescope is dedicated to performing quick and deep scans over large areas of the sky at near-infrared wavelengths. With a 4.1-meter diameter mirror, it is the largest survey telescope in the world, and is ideally suited to studying star birth.
A cosmic lagoon
Stars typically form in large molecular clouds of gas and dust, which eventually collapse under their own weight. The Lagoon Nebula, however, has some additional features. This nursery is also home to a number of much more compact regions of collapsing gas and dust, known as Bok globules.
These regions are named after Bart Bok, a Dutch-American astronomer who first noticed the dark spots in regions of star formation. Bok speculated that they may be associated with the earliest stages of star formation, but hidden baby stars were only directly observed several decades later with the invention of infrared imaging.
Bok globules are so dense that, even in the infrared, they can sometimes block the starlight coming from background stars.
Still, the most famous dark feature in the Lagoon Nebula is the one for which it received its name – a lagoon-shaped dust lane that winds its way through the glowing cloud of gas.
The bright glow of the nebula is caused by the intense ultraviolet light from hot, young stars. But, the Lagoon Nebula is also home to stars much earlier in their stellar infancy – so young that they are still surrounded by their natal accretion disks.
These newborn stars occasionally emit jets of matter from their poles. When this ejected material ploughs into the surrounding gas, bright but short-lived streaks are formed. These features, called Herbig-Haro objects, make the newborn stars easy to spot.
In the last five years, several Herbig-Haro objects have been detected in the Lagoon Nebula, signifying the baby boom is still very much in full swing.
By: Susie77, 7:21 PM GMT on January 03, 2011
QUADRANTID METEOR ALERT: Earth is about to pass through a narrow stream of debris from shattered comet 2003 EH1, source of the annual Quadrantid meteor shower. "Peaking in the wee morning hours of Tuesday, Jan. 4, the Quads have a maximum rate of about 100 per hour (varies between 60 and 200)," says Bill Cooke of NASA's Meteoroid Environment Office. "What makes this year so special is that the Moon is New on the night of the peak, so there will be no interference from moonlight." Click here for more information and observing tips.
From Space Weather
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