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Mission Operations Status (Updated: 2014-Apr-14)

The GRACE Operations Status depends on the health of the battery and the duration within each orbit when the battery is in use. The Status will be updated here approximately every week.

CURRENT STATUS:

    Science Instrument Status:
    • The mission resumed full science data collection since UTC 07:14, Feb 23, 2014, when the GRACE-2 MWA was switched on. The GRACE-1 MWA had been switched on at 07:06 on Feb 21, 2014. In all, the KBR data was missing for only 35 days during this beta_prime=0 event.
    • Unlike previous beta_prime=0 events, the accelerometer remained powered-on throughout the shadow cycle.
    • As before, the GPS and star-camera data were collected continuously.


    beta_prime: 40 deg; Altitude: 421 km; Separation: 236 km

    PEAK beta_prime=77 deg, Apr 22, 2014
    NEXT beta_prime=0 event, Jul 14, 2014
    PEAK beta_prime=-86 deg, Oct 05, 2014

SCIENCE DATA PRODUCTS:

  • 2014
    • Jan-2014 Level-2 product delivered (Jan 1 to Jan 17, 2014)
  • 2013: Level-2 and Level-1B data products were delivered for every month except for the following spans, for which only partial Level-1B data were delivered:
    • Feb 27 to April 10, 2013 [Level-2 product for March was not delivered]
    • Aug 05 to Sep 24, 2013 [Level-2 products for August & September were not delivered]
  • 2012: Level-2 and Level-1B data products were delivered for every month except the following spans, for which only partial Level-1B data were delivered:
    • Apr-20 to May-31, 2012
    • Sep-26 to Nov-05, 2012
  • 2011: Level-2 and Level-1B data products were delivered for every month except the following spans, for which only partial Level-1B data were delivered:
    • Jan-01 to Feb-06, 2011
    • Jun-01 to Jul-06, 2011
    • Nov-17 to Dec-12, 2011

BACKGROUND:

The GRACE Science Operations concept for the remainder of the mission is driven by the intersection of two factors. First is the project decision to operate the spacecrafts in a manner that maximizes the remaining lifetime, so that the longest possible climate data record is available from GRACE. The second is the degraded battery capacity that limits the availability of the power in certain orbital configurations.

The GRACE orbit plane precesses at -1.117 degrees/day relative to the Sun, such that the Sun is in the orbit plane every 161 days. Due to the power system status and desire for longevity, this event will henceforth define a 161-day work cycle for science operations. As long as the beta_prime angle (angle between the orbit plane and the Earth-Sun line) is greater than 69 degrees, the satellite operates using power only from its solar array. For smaller beta_prime angles, the satellites operates partly using the arrays, and partly using the battery. When beta_prime is near zero (i.e. Sun is in the orbit plane), the battery may be used for as much a 40 minutes out of 90 minutes in each orbit. Near beta_prime=0 events, the mission operations status depends on the battery health and operating environment.

This Status will be updated here approximately every week.

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The GRACE mission is jointly implemented by NASA and DLR under
the NASA Earth System Science Pathfinder Program.

Last Modified: Mon Apr 14, 2014
CSR/TSGC Team Web