Volume: 05, Issue: 05 10/25/2006 
Artists conceptual drawing of the two spacecraft in orbit around the sun. 
Image credit: NASA.
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Pad 17-B at Cape Canaveral Air Force Station, workers check the placement of the first half of the fairing around the STEREO spacecraft. Image credit: NASA/George Shelton.
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Mounted onto the STEREO Spacecraft are four instrument packages: SECCHI, SWAVES, IMPACT, and PLASTIC Image Credit: APL.
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Other Articles in This Issue:
ESA Astronaut Christer Fuglesang Gets Ready for the Next Shuttle Mission
Planet-Finding by Numbers
NASA Announces New Student Aeronautics Competition
Air Force Association Grant
 

STEREO Poised for Launch

The STEREO (Solar TErrestrial RElations Observatory) mission is about to begin. Safely installed atop a Boeing Delta II rocket, the twin spacecraft are ready for launch on October 25, 2006. The vehicle's second stage was loaded with storable propellants on October 23. The launch weather forecast remains favorable, with virtually no concerns. There is only a 5% chance of weather violating constraints, due to possible development of thick clouds.

STEREO is the third mission in NASA's Solar Terrestrial Probes program (STP). This two-year mission will provide a unique and revolutionary view of the Sun-Earth System. The two nearly identical observatories - one ahead of Earth in its orbit, the other trailing behind - will trace the flow of energy and matter from the Sun to Earth as well as reveal the 3D structure of coronal mass ejections and help us understand why they happen. STEREO will also provide alerts for Earth-directed solar ejections, from its unique side-viewing perspective adding it to the fleet of Space Weather detection satellites.

Why the need for STEREO? Coronal mass ejections (CMEs), are powerful eruptions that can blow up to 10 billion tons of the Sun's atmosphere into interplanetary space. Traveling away from the Sun at speeds of approximately one million mph (1.6 million kph), CMEs can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with Earth's magnetosphere.

Large geomagnetic storms directed towards Earth can damage and even destroy satellites, are extremely hazardous to astronauts when outside of the protection of the Space Shuttle or International Space Station performing Extra Vehicular Activities (EVAs), and they have been known to cause electrical power outages.

Solar ejections are the most powerful drivers of the Sun-Earth connection. Yet despite their importance, scientists do not fully understand the origin and evolution of CMEs, nor their structure or extent in interplanetary space. STEREO's unique stereoscopic images of the structure of CMEs will enable scientists to determine their fundamental nature and origin.

For more information, please visit the following websites:
http://www.nasa.gov/mission_pages/stereo/main/index.html
http://stereo.gsfc.nasa.gov/orbit.shtml.

    
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