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GRACE operational issue: Planned switch-on of Microwave Assemblies and Accelerometer Instrument Control Units

11 May 2016

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

  • 5 May 2016, 10:36 UTC: GRACE-B ICU
  • 5 May 2016, 10:46 UTC: GRACE-A ICU
  • 6 May 2016, 09:49 UTC: GRACE-A MWA
  • 7 May 2016, 11:00 UTC: GRACE-B MWA

The GRACE-B MWA has been ON in sunlight and OFF for 29 minutes during eclipse. GRACE-B MWA time OFF has progressively been decreased since then. Permanent operations will be resumed mid till end of May.

On 5 April 2016 an orbit manoeuvre was 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 coming months. The two satellites had a minimum distance of 120 m on 21 April - GRACE-A became the leading satellite. Two drift stop manoeuvres (requiring 180 degree yaw turns) on GRACE-B on 4 May finished the swap.