From: Goddard Space Flight Center
Posted: Thursday, June 19, 2003
This afternoon (2003 June 19), SOHO engineers and Flight Operations Team (FOT) were able to use both sets of antenna Z-axis motor drive windings simultaneously to move the high gain antenna (HGA) toward the "sweet spot" in east-west offset that will allow the shortest interruption in scientific telemetry.
As of 20:20 UT, the FOT is attempting to finish to move to the sweet spot (an E-W offset of -17.7°), which would limit the "keyhole" in high-rate telemetry to about 19 days (out of every three months), starting late next week.
We will be having a SOHO science Working Team (SWT) telecon tomorrow morning, and plan to spend the next few weeks, including the keyhole, to decide on the course of action that maintains the highest level of scientific return with the minimum risk of more serious interruptions.
A preliminary look at the costs and benefits of changing the SOHO orbit indicate that reducing the ecliptic Y (E-W) extent of the orbit by a factor of ~ 2 would require more fuel than we have on board. There are lots of other options, however, and Flight Dynamics Facility will be examining a wide variety and presenting them to the program[me] office and SWT.
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