Pick of The Week
 
 

Turning Things Around (September 14, 2006)


Hi-res TIF image(3.0M)

If one compares two images from SOHO's C3 coronagraph on September 11, 2006, you can detect something has changed. The rather faint and obscure metal armature that holds the centered, blue occulting disk over the telescope lens (where the Sun would be) has moved 180 degrees from one image to the next. Why?

The SOHO spacecraft itself performed a 180 degree rotation and for many hours was taking no imagery that day during the maneuver. For the past few years SOHO has had a jammed antenna on one axis . Since only one axis among two of the antenna mechanism can be used, sometimes the antenna can not be pointed toward earth. To increase its ability to send at least some communications back to NASA's Deep Space Network here on Earth, SOHO has to rotate itself so that more of its signals can be received. Some of the time every few months, due to its orbit, it cannot send as much data and images back. We call this its keyhole period.

Such are the aches and pains of a spacecraft that is over 10 years old, a remarkable age of a spacecraft. However, we make sure that the images themselves are rolled right side up here on the ground so the solar north pole is always "up".

Previous Picks of the Week

SOHO began its Weekly Pick some time after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display.

If your institution would also like to receive the same Weekly Pick from us for display (usually in Photoshop or QuickTime format), please send your inquiry to steele.hill@gsfc.nasa.gov.

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