Контрольная работа по "Английскому языку"

Dolores Beasley

Headquarters, Washington, DC              Nov. 14, 2001

Phone: 202/358-1753 

RELEASE: 01-222 

NASA LEONIDS ACTIVITIES: SLEEPYHEADS MAY MISS SPECTACULAR CELESTIAL DISPLAY 

     Early birds may catch more than their proverbial worms this week. In the predawn hours of Sunday, Nov.18, the annual Leonid meteor shower may put on one of its best shows in decades, according to various scientists modeling the expected Leonid activity this year. 

"It's time to set your alarm clocks and get yourself out under a dark sky," said Dr. Donald Yeomans, head of NASA's Near Earth Object program office, at the Jet Propulsion Laboratory, Pasadena, Calif. "This could be the last opportunity for watching an impressive meteor storm in a dark sky for decades to come." 

Meteors, also called shooting stars, are really streaks of light that flash across the sky as bits of dust and rock in space collide with the Earth's upper atmosphere and vaporize. The Leonid shower appears every year around Nov. 17 or 18 as the Earth intersects the orbit of comet Tempel-Tuttle and runs into streams of dust shed by the comet. Best viewing times this year are predicted to be the early morning hours of November 18, with the peak activity expected around 5 a.m. EST. 

They are called Leonid meteors for the direction in the sky from which they appear to originate -- the constellation Leo. Because the stream of comet dust hits the Earth almost head-on, the Leonids are among the fastest meteors around -- they zip silently across the sky at 44 miles per second. Every so often, the Earth passes through an especially dense clump of dust from Tempel-Tuttle, and a truly spectacular meteor storm occurs -- the great Leonid storm of 1966 produced 150,000 meteors per hour. 

Four NASA centers -- Marshall Space Flight Center, Huntsville, Ala.; Goddard Space Flight Center, Greenbelt, Md.; Ames Research Center, Moffett Field, Calif.; and the Jet Propulsion Laboratory, Pasadena, Calif. -- have activities scheduled around this year's meteor shower. 

At Marshall, researchers will use special cameras to scan the skies and report meteor activity around the clock Nov. 17 and 18. From six key points on the globe, they will record and transmit their observations to Marshall's Leonid Environment Operations Center, a data clearinghouse that will provide meteor updates in near real-time through: http://www.SpaceWeather.com -- a Web site sponsored by science@nasa.gov. 

"We're collecting this data to analyze and refine our meteor-forecasting techniques," said Dr. Rob Suggs, the Leonid Environment Operations Center team leader. "If we can better determine where, when and how the meteors will strike, we can take protective measures to prevent or minimize damage to our spacecraft." 

The researchers, along with colleagues from the University of Western Ontario in Canada and the U.S. Air Force, will monitor the storm from six locations, Huntsville, Ala.; Eglin Air Force Base, Fla.; Maui, Hawaii; Sunspot, N.M.; the U.S. Territory of Guam; and the Gobi Dessert in Mongolia. Each location was selected based on meteor forecasts and the area's climate. 

The monitoring team also has the capability to detect meteors the casual observer may miss. Using special image-intensified cameras that can detect faint objects even in low-light conditions, the researchers will monitor the shower, using the video screens as windows to the skies.  Every hour, the teams will relay their observations to the Marshall control center, helping to paint a comprehensive picture of the meteor storm. 

Most Leonid particles are the size of dust grains, and will vaporize very high in the atmosphere, so they present no threat to people on the ground or even in airplanes. However, there is a slight chance that a satellite could be damaged if it were hit by a Leonid meteor. The meteors are too small to simply blow up a satellite. However, the Leonids are moving so fast they vaporize on impact, forming a cloud of electrified gas called plasma. Since plasma can carry an electric current, there is a risk that a Leonid-generated plasma cloud could cause a short circuit in a satellite, damaging sensitive electronic components. 

Goddard Space Flight Center is responsible for controlling many satellites for NASA and other organizations and is taking precautions to mitigate the risk posed by the Leonids. These include pointing instrument apertures away from the direction of the Leonid stream, closing the doors on instruments where possible, turning down high voltages on systems to prevent the risk of a short circuit, and positioning satellites to minimize the cross-section exposed to the Leonids. 

Goddard controls or manages 21 satellites in the earth and space sciences. It also manages NASA's Tracking and Data Relay Satellite System constellation, which is controlled from White Sands, N.M. 

At Ames, meteor experts Dr. David Morrison, chief scientist at NASA's Astrobiology Institute, and Dr. Scott Sanford, a NASA planetary scientist, will be available Friday, Nov. 16, at Ames for media interviews about the Leonid meteor storm.

-more-

-3-

The scientists will discuss NASA's airborne mission to study the Leonids, the danger the meteors could pose to satellites, recent Leonid prediction models and the latest research, which suggests that meteors may have played a role in the origin of life.

On Nov. 18, a team of 19 astrobiologists from five countries will depart from southern California's Edwards Air Force Base on an NKC-135 research aircraft to keep an eye on the sky for satellite operators and to study the processes that may have jump-started life on Earth. The 418th Flight Test Squadron at Edwards Air Force Base operates the research aircraft, which flew previous Leonid Multi-instrument Airborne Campaign (MAC) missions in 1998 and 1999 over Japan and Europe. 

Many scientists think meteors might have showered the Earth with the molecules necessary for life's origin. "We are eager to get another chance to find clues to the puzzling question of 'What happens to the organic matter brought in by the meteoroids?'" said Dr. Michael Meyer, lead scientist for astrobiology at NASA Headquarters, Washington, which is sponsoring the airborne observing mission. 

Astrobiology is the study of the origin, evolution, distribution and future of life in the universe. Ames is NASA's lead center for astrobiology and the location of the central offices of the NASA Astrobiology Institute, an international research consortium. 

Information about the Leonid Multi-instrument Airborne Campaign (MAC) and live Leonid coverage are available at: http://leonid.arc.nasa.gov/ or http://www-space.arc.nasa.gov/~leonid/ 

Observers can calculate local meteor rates using their home computers via: http://www.space.arc.nasa.gov/~leonid/fluxestimator.html The Jet Propulsion Laboratory (JPL) will host a webcast with Yeomans explaining what the Leonids are and how to see them on the JPL Web site at: http://www.jpl.nasa.gov 

NASA TV will broadcast live commentary and video of the Leonids from 12:30 a.m. to 6 a.m. EST Sunday, Nov. 18. The broadcast, originating from Marshall, will feature live video of the Leonids meteor shower provided by a video camera with enhanced images and animation. If weather and cloud cover inhibit observation, the broadcast will be cancelled and regular programming resumed. 

NOTE TO EDITORS: More information on Leonids activities at specific NASA Centers is available from: Steve Roy, Marshall Space Flight Center, at: 256/544-6535; Bill Steigerwald, Goddard Space Flight Center, at: 301/286-5017; Kathleen Burton, Ames Research Center, at: 650/604-1731; Martha Heil, Jet Propulsion Laboratory, at: 818/354-0850.

-end- 

* * * 

NASA press releases and other information are available automatically by sending an Internet electronic mail message to domo@hq.nasa.gov. In the body of the message (not the subject line) users should type the words "subscribe press-release" (no quotes).  The system will reply with a confirmation via E-mail of each subscription.  A second automatic message will include additional information on the service. NASA releases also are available via CompuServe using the command GO NASA.  To unsubscribe from this mailing list, address an E-mail message to domo@hq.nasa.gov, leave the subject blank, and type only "unsubscribe press-release" (no quotes) in the body of the message.