AAS 207th Meeting, 8-12 January 2006
Session 115 JWST
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[115.21] Scheduling JWST Observations at L2

K. S. Long, J. C. Isaacs, W. Kinzel, L. Petro, P. Stanley, H. S. Stockman (STScI)

JWST will be the first general purpose astronomical observatory to be located at L2. In many respects, JWST operations will resemble that of other well-known space observatories. The planning and scheduling process will involve establishing planning windows for each approved observation in the form of a long range plan, and then a detailed sequence of observations, an operations plan, that will be uplinked to the observatory. Unlike HST, JWST operations will be event rather than absolute time driven, an approach which allows the observatory to operate efficiently even if individual observations fail (as a result of acquisition failures). Event driven operations are well matched to a JWST's L2 orbit, since targets have long visibility intervals (uninterrupted by earth occultations). Solar radiation pressure on the JWST sunshield causes angular momentum buildup in the reaction wheels that point and inertially stabilize the observatory (unlike HST). The stored momentum can be unloaded, but the process uses a limited resource -- propellant -- both during the momentum dump itself and indirectly by increasing the fuel required for stationkeeping. Since propellant and is limited, targets must be scheduled so that the number of momentum dumps is limited. This must be done while meeting the science and observatory requirements on the observations. Here we describe some of the strategies that have been developed to schedule JWST during its science operations phase.

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