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GRACE Operational Issue: Planned switch-on of Microwave Assemblies

05 August 2014

The GRACE-A and -B Microwave Assemblies (MWA) and Accelerometer Instrument Control Units (ICU) have been switched-on again on the below dates:

  • 31 July 2014, 14:00 UTC: GRACE-A and GRACE-B MWA (80% average on-time)
  • 02 August 2014, 14:00 UTC: GRACE-A and GRACE-B MWA (continuously on)
  • 28 July 2014, 13:11 UTC: GRACE-A and GRACE-B ICU

Additionally on 30 June an orbit manoeuvre has been executed on GRACE-B in order to accelerate the drift towards GRACE-A as initiation of a satellite switch. The satellite swap intends to save fuel on GRACE-B by staying on the better performing GRACE-B star camera for the second half of 2014. During the manoeuvre the two satellites had a minimum distance of 400 m on 14 July. A drift stop manoeuvre followed by a 180 degree yaw turn of both satellites on 28 July finished the swap.