Solar Panorama: Twin NASA Probes Take Wide Look at Sun
A close up of the sun in extreme ultraviolet light taken by STEREO's Extreme Ultraviolet Imager (EUVI). Featured are magnetic loops filled with million-degree Celsius material.
Credit: NASA/NRL

Twin NASA probes aimed at the Sun are sending home super-sized panoramas of Earth's nearest star as they take up positions to track explosive solar storms.

Instruments and cameras aboard NASA's two Solar Terrestrial Relations Observatory (STEREO) spacecraft have zoomed out for a planetary orbit-hopping view that stretches from the Sun to Earth's orbit, a distance of 93 million miles (150 million kilometers). The panorama [image] serves as a shakedown for STEREO's science tools to take three-dimensional scans of the Sun's coronal mass ejections (CMEs), the first of which are expected in April [new video].

"This panoramic view is absolutely unique," Russ Howard, principal investigator for the STEREO instruments that took the new images, told reporters Thursday, adding that the probes have already spotted a CME event. "We're still seeing the evolution of this material as it goes out into to interplanetary space."

Howard leads STEREO's five-imager Sun-Earth Connection Coronal and Heliospheric Investigation (SSECHI) instrument suite for NASA at the Naval Research Laboratory in Washington, D.C. [image].

CMEs are massive eruptions from Sun that spew high-energy particles at prodigious speeds which, if they pass by Earth, can pose radiation hazards for astronauts in space, afflict orbiting satellites and interfere with power and communications systems on Earth.

"They can get their memories reset or power supplies wiped out," mission project scientist Michael Kaiser, of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said of CME-susceptible spacecraft, during Thursday's press briefing. "They need to know when [CMEs] are coming so they can be set in safe mode."

STEREO's planned two-year mission is expected to build near real-time 3-D views of those eruptions by positioning twin Sun-watching probes at stations leading and trailing the Earth in its orbit [image]. The mission, researchers hope, will yield better forecasts for severe space weather and determine how CMEs speed up and slow down as they flow out from the Sun.

The mission's two spacecraft spotted a CME event between Jan. 24 and Jan. 25, and watched as the eruptions first sped away from the Sun at more than 750 miles (1,207 kilometers) per second only to slow to about 500 miles (804 kilometers) per second. The observations also caught the last vestiges of the tail of Comet McNaught, the brightest comet seen in 30 years, mission scientists said [image].

"This is a discovery. ... We have never been able to see the progress of the CME from the Sun, from its origin, all the way out," Dan Moses, a SSECHI science team member at the Naval Research Laboratory. "We see that this is different from our initial models."

Since their October 2006 launch, STEREO's two probes, dubbed A and B for "Ahead" and "Behind," have not yet traveled far enough apart to begin their three-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 one circuit in 387 days [image].

Mission managers said the STEREO probes are in good health and have enough propellant onboard 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.

Madhulika Guhathakurta, 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 to museums nationwide and via the Internet.

"These images are just unbelievable," Guhathakurta said of the new panoramas.

NASA has compiled a list of 3-D glasses resources, available by clicking here.