When the Sun Gets in the Way: Stereo Science Observations on the Far Side of the Sun

Friday, 19 December 2014
William T Thompson1, Joseph B Gurman2, Janet G Luhmann3, David W Curtis3, Peter C Schroeder3, Richard A Mewaldt4, Andrew J Davis4, Kristin Wortman5, Christopher T Russell6, Antoinette Broe Galvin7, Mark Popecki8, Lynn M Kistler9, Lorna Ellis8, Russell Howard10, Angelos Vourlidas11, Nathan Rich11, Lynn Hutting10, Milan Maksimovic12, Stuart D Bale3 and Keith Goetz13, (1)ADNET Systems Inc. Greenbelt, Greenbelt, MD, United States, (2)NASA Goddard SFC, Greenbelt, MD, United States, (3)University of California Berkeley, Berkeley, CA, United States, (4)Caltech, Pasadena, CA, United States, (5)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (6)Univ California, Los Angeles, CA, United States, (7)Univ of New Hampshire, Durham, NH, United States, (8)University of New Hampshire, Durham, NH, United States, (9)University of New Hampshire Main Campus, Durham, NH, United States, (10)U.S. Naval Research Laboratory, Washington, DC, United States, (11)Naval Research Laboratory, Alexandria, VA, United States, (12)CNRS, Paris Cedex 16, France, (13)University of Minnesota Twin Cities, Minneapolis, MN, United States
With the two STEREO spacecraft on the opposite side of the Sun from Earth, pointing the high gain antenna at Earth means that it's also pointed very close to the Sun. This has resulted in unexpectedly high temperatures in the antenna feed horns on both spacecraft, and is forcing the mission operations team to take corrective action, starting in August 2014 for STEREO Ahead, and December 2014 for STEREO Behind. By off-pointing the antennas to use one of the lower power side lobes instead of the main lobe, the feed horn temperatures can be kept at a safe level while still allowing reliable communication with the spacecraft. However, the amount of telemetry that can be brought down will be highly reduced. Even so, significant science will still be possible from STEREO's unique position on the solar far side. We will discuss the science and space weather products that will be available from each STEREO instrument, when those products will be available, and how they will be used. Some data, including the regular space weather beacon products, will be brought down for an average of a few hours each day during the daily real-time passes, while the in situ and radio beacon data will be stored on the onboard recorder to provide a continuous 24-hour coverage for eventual downlink once the spacecraft is back to normal operations.