Twin NASA probes aimed at the Sun are sending home super-sized panoramasof Earth's nearest star as they take up positions to track explosive solarstorms.
Instrumentsand cameras aboard NASA's two SolarTerrestrial Relations Observatory (STEREO) spacecraft have zoomed out for aplanetary orbit-hopping view that stretches from the Sun to Earth's orbit, a distance of93 million miles (150 million kilometers). The panorama [image]serves as shakedown for STEREO's science toolsto take three-dimensional scans of the Sun's coronalmass ejections (CMEs), the first of which are expected in April [newvideo].
"Thispanoramic view is absolutely unique," Russ Howard, principal investigator forthe STEREO instruments that took the new images, told reporters Thursday,adding that the probes have already spotted a CME event. "We're still seeingthe evolution of this material as it goes out into to interplanetary space."
Howardleads STEREO's five-imager Sun-Earth ConnectionCoronal and Heliospheric Investigation (SSECHI) instrumentsuite for NASA at the Naval Research Laboratory in Washington, D.C. [image].
CMEs aremassive eruptions from Sun that spew high-energy particles atprodigious speeds which, if they pass by Earth, can poseradiation hazards for astronauts in space, afflictorbiting satellites and interfere with power and communications systems on Earth.
"They canget their memories reset or power supplies wiped out," mission projectscientist Michael Kaiser, of NASA's Goddard Space Flight Center in Greenbelt,Maryland, said of CME-susceptible spacecraft, during Thursday'spress briefing. "They need to know when [CMEs] are coming so they can be set insafe mode."
STEREO's plannedtwo-year mission is expected to build near real-time 3-D views of thoseeruptions by positioning twin Sun-watching probes at stations leading andtrailing the Earth in its orbit [image].The mission, researchers hope, will yield better forecasts for severe space weather and determine howCMEs speed up and slow down as they flow out from the Sun.
Themission's two spacecraft spotted a CME event between Jan. 24 and Jan. 25, andwatched as the eruptions first sped away from the Sun at more than 750 miles (1,207kilometers) per second only to slow to about 500 miles (804 kilometers) per second.The observations also caught the last vestiges of the tail of CometMcNaught, the brightest comet seen in 30 years, mission scientists said [image].
"This is adiscovery. ... We have never been able to see the progress of the CME from theSun, from its origin, all the way out," Dan Moses, a SSECHI science team memberat the Naval Research Laboratory. "We see that this is different from ourinitial models."
Since theirOctober 2006 launch, STEREO's two probes, dubbed A and B for "Ahead" and"Behind," have not yet traveled far enough apart to begin theirthree-dimensional Sun observations. Once in their final positions in April,STEREO A--ahead of Earth--will make a complete orbit around the Sun in 347 days,while STEREO B-- behind and further out of Earth's orbit--will complete onecircuit in 387 days [image].
Missionmanagers said the STEREO probes are in good health and have enough propellantonboard to last a decade. The Applied Physics Laboratory at Johns Hopkins University in Laurel, Maryland, is overseeing the $550 million mission for NASA's Goddard Space Flight Center.
MadhulikaGuhathakurta, NASA's STEREO program scientist at the agency's Washington, D.C.headquarters, pledged that STEREO's first 3-D Sun images will be released tomuseums nationwide and via the Internet.
"Theseimages are just unbelievable," Guhathakurta said of the new panoramas.
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