sábado, 21 de julio de 2012

Astronomy: NASA Telescope Captures Sharpest Images of Sun's Corona

Hi My Friends: A VUELO DE UN QUINDE EL BLOG., A telescope launched July 11 aboard a NASA sounding rocket has captured the highest-resolution images ever taken of the sun's million-degree atmosphere called the corona. The clarity of the images can help scientists better understand the behavior of the solar atmosphere and its impacts on Earth's space environment.
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Venus appears as a black dot on the lower left edge of the sun in this image from NASA's Transition Region and Coronal Explorer (TRACE), captured during the 2004 transit. Credit: NASA/TRACE/LMSAL


On June 5, 2012 at 6:03 PM EDT, the planet Venus will do something it has done only seven times since the invention of the telescope: cross in front of the sun. This transit is among the rarest of planetary alignments and it has an odd cycle. Two such Venus transits always occur within eight years of each other and then there is a break of either 105 or 121 years before it happens again.

The moments when Venus first appears to cross the limb of the sun and the moments it leaves, known as ingress and egress respectively, are historically the most scientifically important aspects of the transit since comparison of Venus's journey viewed from different points on Earth provided one of the earliest ways to determine the distance between Earth and the sun. The transit is also helpful to scientists today: NASA's Solar Dynamics Observatory (SDO) will be watching the June 2012 transit to help calibrate its instruments as well as to learn more about Venus's atmosphere.

Since the points at which Venus will first touch and later leave the sun is known down to minute detail, SDO can use this information to make sure its images are oriented to true solar North. Orienting instruments is a constant adjustment game for telescopes in space, since their original position can be shifted during launch. Various calibrations throughout the two years SDO has been in space have left the scientists confident that the instruments are highly accurate, but making sure that Venus appears in the SDO images exactly where scientists know it should be will help make sure SDO's orientation is accurate to within a tenth of a pixel.

Second, the SDO team can use the lightless center of Venus to help calibrate what is called the point spread function of the telescope. This function describes how much light leaks from one pixel into others around it. Since there is no light emitted from the very center of Venus as it crosses the sun, it serves as a perfect test case for an area of the image where the pixels should remain black. By measuring how much light bleeds into those pixels from the rest of the sun, the SDO team will have a better sense of how to correct for that. These measurements also help us to understand the black drop effect – in which a tiny black spot appears to connect Venus to the limb of the sun -- that bedeviled scientists' attempts to measure the exact position of Venus during transits in the 18th and 19th centuries.

And last, the SDO team hopes to learn more about Venus's atmosphere as it is partially transparent to the extreme ultraviolet light observed by the telescopes on SDO. Venus will appear to be a little bigger in longer wavelengths (such as 304) as compared to shorter wavelengths (such as 171). This difference tells us how much oxygen is in Venus’s atmosphere.

More information from SDO about the Venus Transit (and SDO footage of the transit available June 5 and June 6:
 
 


EVE Underflight Calibration Sounding Rocket Launches Successfully
06.23.12
 
UPDATE: June 23, 2012, 13:30 MDT: The NASA EVE Underflight Calibration Sounding Rocket launched successfully. Based on the quicklook realtime data, all of the rocket EVE instrument channels appear to have made excellent solar EUV irradiance measurements. The two new soft X-ray spectrometers appear to have worked too. Detailed data analysis will be done to further analyze the quality of the rocket data and to produce a solar EUV irradiance reference spectrum that then can be used to calibrate the satellite SDO EVE and other solar EUV instruments.
  http://www.youtube.com/watch?feature=player_embedded&v=TTfgOYb1Fn8
 http://www.youtube.com/watch?feature=player_embedded&v=TTfgOYb1Fn8
 On March 23, 2011, two on-board cameras followed a sounding rocket on its journey from Earth to space and back again. The rocket was launched to measure solar energy output and calibrate the EVE instrument on the Solar Dynamics Observatory. Credit: NASA
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The Solar Dynamics Observatory (SDO) was launched on 11 February 2010, and the EUV Variability Experiment (EVE), one of the three solar instruments aboard SDO, began normal operations on 1 May 2010. As part of the planned SDO EVE program, sounding rockets are flown regularly to provide underflight calibrations in order to more accurately track instrument degradation trends.

The principal investigator is Dr. Tom Woods from the Laboratory For Atmospheric And Space Physics, University of Colorado.

The next launch of the EVE underflight calibration sounding rocket payload is planned for June 23, 2012 at 13:00 MDT (window 13:00 - 13:30 MDT) (3:00pm EDT) from the White Sands Missile Range. This flight's primary purpose is to provide the third underflight calibration for the SDO EVE satellite instrument. Launch time is near local noon to minimize the atmospheric absorption of the solar EUV radiation during the rocket observations.

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NASA Telescope Captures Sharpest Images of Sun's Corona
 
 
WASHINGTON -- A telescope launched July 11 aboard a NASA sounding rocket has captured the highest-resolution images ever taken of the sun's million-degree atmosphere called the corona. The clarity of the images can help scientists better understand the behavior of the solar atmosphere and its impacts on Earth's space environment.

"These revolutionary images of the sun demonstrate the key aspects of NASA's sounding rocket program, namely the training of the next generation of principal investigators, the development of new space technologies, and scientific advancements," said Barbara Giles, director for NASA's Heliophysics Division at NASA Headquarters in Washington.

Launched from White Sands Missile Range in New Mexico, the 58-foot-tall sounding rocket carried NASA's High Resolution Coronal Imager (Hi-C) telescope. Weighing 464 pounds, the 10-foot-long payload took 165 images during its brief 620-second flight. The telescope focused on a large active region on the sun with some images revealing the dynamic structure of the solar atmosphere in fine detail. These images were taken in the extreme ultraviolet wavelength. This higher energy wavelength of light is optimal for viewing the hot solar corona.

"We have an exceptional instrument and launched at the right time," said Jonathan Cirtain, senior heliophysicist at NASA's Marshall Space Flight Center in Huntsville, Ala. "Because of the intense solar activity we're seeing right now, we were able to clearly focus on a sizeable, active sunspot and achieve our imaging goals."

The telescope acquired data at a rate of roughly one image every 5 seconds. Its resolution is approximately five times more detailed than the Atmospheric Imaging Assembly (AIA) instrument flying aboard NASA's Solar Dynamics Observatory (SDO). For comparison, AIA can see structures on the sun's surface with the clarity of approximately 675 miles and observes the sun in 10 wavelengths of light. Hi-C can resolve features down to roughly 135 miles, but observed the sun in just one wavelength of light.

The high-resolution images were made possible because of a set of innovations on Hi-C's optics array. Hi-C's mirrors are approximately 9 1/2 inches across, roughly the same size as the SDO instrument's. The telescope includes some of the finest mirrors ever made for space-based instrumentation. The increase in resolution of the images captured by Hi-C is similar to making the transition in television viewing from a cathode ray tube TV to high definition TV.

Initially developed at Marshall, the final mirror configuration was completed with inputs from partners at the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Mass., and a new manufacturing technique developed in coordination with L-3Com/Tinsley Laboratories of Richmond, Calif.

The high-quality optics were aligned to determine the spacing between the optics and the tilt of the mirror with extreme accuracy. Scientists and engineers from Marshall, SAO, and the University of Alabama in Huntsville worked to complete alignment of the mirrors, maintaining optic spacing to within a few ten-thousandths of an inch.

NASA's suborbital sounding rockets provide low-cost means to conduct space science and studies of Earth's upper atmosphere. In addition, they have proven to be a valuable test bed for new technologies for future satellites or probes to other planets.

Launched in February 2010, SDO is an advanced spacecraft studying the sun and its dynamic behavior. The spacecraft provides images with clarity 10 times better than high definition television and provides more comprehensive science data faster than any solar observing spacecraft in history.

Partners associated with the development of the Hi-C telescope also include Lockheed Martin's Solar Astrophysical Laboratory in Palo Alto, Calif.; the University of Central Lancashire in Lancashire, England; and the Lebedev Physical Institute of the Russian Academy of Sciences in Moscow.

For more information about SDO, visit:

http://www.nasa.gov/sdo

For more information about NASA's sounding rocket program, visit:

http://sites.wff.nasa.gov/code810/

For more information about Hi-C, visit:

http://www.nasa.gov/topics/solarsystem/features/hic.html
 NASA
Guillermo Gonzalo Sánchez Achutegui
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ayabaca@yahoo.com 
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