Comunicato del 14 novembre 2001

> Contacts:  NASA Headquarters/Dolores Beasley  202-358-1753 

>            JPL/Martha Heil 818-354-0850


> FOR IMMEDIATE RELEASE                     November 14, 2001




>      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."


>      Yeomans explains what the Leonids are and how to see 

> them, in a video on the JPL Web site at: 

> .


>      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 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 2 a.m. PST 

> (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 Earth almost head-

> on, the Leonids are among the fastest meteors around -- they 

> zip silently across the sky at nearly 70 kilometers per second 

> (44 miles per second). Every so often, 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 -- JPL; Marshall Space Flight Center, 

> Huntsville, Ala.; Goddard Space Flight Center, Greenbelt, Md.; 

> and the Ames Research Center, Moffett Field, 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 

> -- a Web site sponsored by 



>      "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. 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 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, D.C. 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 and live Leonid coverage are available at:  

> or 

> .


>      Observers can calculate local meteor rates using their 

> home computers via: 

> .


>      NASA TV will broadcast live commentary and video of the 

> Leonids from 9:30 a.m. to 3 a.m. PST (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.


>      JPL is managed for NASA's Office of Space Science, 

> Washington, D.C., by the California Institute of Technology in 

> Pasadena.


> NOTE TO EDITORS: More information on Leonids activities at 

> specific NASA Centers is available from: Martha Heil, JPL, at: 

> 818/354-0850; 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;.


>                    # # # # #

> 11/14/01   JP

> 2001-219


> ---------------------------------------------------------------

> You are subscribed to JPL's news mailing list.  

Per maggiori informazioni scrivete a

Vai ai Comunicati
Vai ai Testi del CAST
Vai a Fotografia, ccd e ricerca
Vai ai Notiziari

Vai alla Homepage del CAST